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周期性羽化昆虫形成机制 被引量:1
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作者 张宇凡 王小艺 《生态学报》 CAS CSCD 北大核心 2024年第11期4478-4488,共11页
当昆虫类群表现为长生命周期k(k>1)年时,成虫的羽化表现为非周期性、周期性和过渡周期性3种形式。非周期性即为成虫每年均羽化,周期性即为成虫每k年才羽化1次,过渡周期性为非周期昆虫逐渐进化为羽化周期性的必经阶段,不同年份羽化的... 当昆虫类群表现为长生命周期k(k>1)年时,成虫的羽化表现为非周期性、周期性和过渡周期性3种形式。非周期性即为成虫每年均羽化,周期性即为成虫每k年才羽化1次,过渡周期性为非周期昆虫逐渐进化为羽化周期性的必经阶段,不同年份羽化的同生群在密度上产生了显著差异,形成了小同生群和优势同生群。自然界中表现出完全羽化周期性的昆虫种类是较少的,但由于其高种群密度的成虫同步性羽化现象,对比非周期性昆虫更易暴发成灾。为明确周期性昆虫演化进程并为林区虫害防控提供理论指导,总结了周期性昆虫的种类和生活特性,不同年间的气候异质性、自然灾害、扩散到未分布区域、天敌、种间和种内竞争等因素均有可能成为过渡周期现象形成的最初驱动力,生活史延长、寄主-天敌互作、低温驱动效应、天敌不敏感-捕食者饱足效应、种间和种内竞争等是促使昆虫羽化周期性形成的可能机制。在林区管理实践中,应提前评估害虫羽化周期性产生的趋势和程度。当成虫表现出完全羽化周期性,应在集中羽化年份内采取见效快的综合防控策略,降低唯一同生群密度至经济阈值以下。当成虫表现出过渡周期性,应加大优势同生群防治力度、降低小同生群防治频率,以及采取天敌林间释放和保育技术以平衡天敌对目标害虫的不同发育阶段种群的控制作用大小,遏制或减缓天敌-寄主互作驱动下的周期性演化进程,逐渐实现由过渡周期阶段向非周期性的逆转。当成虫表现出非周期性,应减少专化性天敌的释放和针对害虫特定阶段的防治措施使用频率,优先选择作用于所有发育阶段且致死率不存在显著差异的防治手段,避免因人为干扰产生的周期性演化和进一步的成灾。 展开更多
关键词 周期性昆虫 进化假说 过渡周期现象 成灾 林区管理
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语料库翻译研究背景下的“translationese”与“翻译共性”刍议
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作者 杨晓琳 李德超 《山东外语教学》 北大核心 2024年第3期108-119,共12页
近年来,在基于语料库的翻译研究背景下,翻译语言特征描写中的两个关键词——“translationese”与“翻译共性”备受关注,两者之间既有区别,亦有交织重叠的地方。在国内翻译研究领域,“translationese”的译名和定义也不尽一致。本研究... 近年来,在基于语料库的翻译研究背景下,翻译语言特征描写中的两个关键词——“translationese”与“翻译共性”备受关注,两者之间既有区别,亦有交织重叠的地方。在国内翻译研究领域,“translationese”的译名和定义也不尽一致。本研究梳理了语料库研究方法背景下两者的概念和研究模式的发展,进而探讨了translationese的连续性特征以及它与翻译共性假设的关系问题,提出以“特征译语”为译名以突出其特点,并阐明了本研究在理论与实践方面的意义。 展开更多
关键词 语料库翻译研究 源语干扰 连续性 翻译共性假设
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子空间不确定下多重假设AMF、Rao与Wald检测方法
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作者 田晗 张宇 +2 位作者 许姗姗 高永婵 许智文 《海军航空大学学报》 2024年第5期622-632,共11页
由于目标多秩子空间大小的不确定性会导致多重假设检测发生,传统目标自适应二元检测方法不再适用。针对此问题,文章提出了子空间不确定下多重假设AMF、Rao与Wald检测方法。首先,基于Kullback-Leibler信息准则,建立了目标多秩子空间存在... 由于目标多秩子空间大小的不确定性会导致多重假设检测发生,传统目标自适应二元检测方法不再适用。针对此问题,文章提出了子空间不确定下多重假设AMF、Rao与Wald检测方法。首先,基于Kullback-Leibler信息准则,建立了目标多秩子空间存在多种假设下的目标检测模型;然后,基于AMF、Rao和Wald检测准则,设计多重假设检测器,并优化估计未知参数与计算惩罚项。最后,通过仿真实验验证了所提检测器的性能,并分析了惩罚项对各检测器性能的影响。实验结果表明,相比传统检测器,所提检测器在一定情况下具有更优的检测性能。 展开更多
关键词 自适应目标检测 多秩子空间 多重假设检测 模型阶次选择
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Island biogeography theory and the habitat heterogeneity jointly explain global patterns of Rhododendron diversity
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作者 Yanwei Guan Yongru Wu +4 位作者 Zheng Cao Zhifeng Wu Fangyuan Yu Haibin Yu Tiejun Wang 《Plant Diversity》 SCIE CAS CSCD 2024年第5期565-574,共10页
Mountain biodiversity is of great importance to biogeography and ecology.However,it is unclear what ecological and evolutionary processes best explain the generation and maintenance of its high levels of species diver... Mountain biodiversity is of great importance to biogeography and ecology.However,it is unclear what ecological and evolutionary processes best explain the generation and maintenance of its high levels of species diversity.In this study,we determined which of six common hypotheses(e.g.,climate hypotheses,habitat heterogeneity hypothesis and island biogeography theory)best explain global patterns of species diversity in Rhododendron.We found that Rhododendron diversity patterns were most strongly explained by proxies of island biogeography theory(i.e.,mountain area)and habitat heterogeneity(i.e.,elevation range).When we examined other relationships important to island biogeography theory,we found that the planimetric area and the volume of mountains were positively correlated with the Rhododendron diversity,whereas the‘mountains-to-mainland’distance was negatively correlated with Rhododendron diversity and shared species.Our findings demonstrate that Rhododendron diversity can be explained by island biogeography theory and habitat heterogeneity,and mountains can be regarded as islands which supported island biogeography theory. 展开更多
关键词 Mountain biodiversity RHODODENDRON Island biogeography theory Habitat heterogeneity Biogeographical hypotheses Plant diversity
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S.D. Krashen's Language Acquisition Theory and the Teaching of Business English Reading
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作者 谭莉 《海外英语》 2015年第4期116-116,119,共2页
This paper first illustrates S.D. Krashen's language acquisition theory, especially two of his five hypotheses as well as the guidance of these theories towards the teaching of business English reading for student... This paper first illustrates S.D. Krashen's language acquisition theory, especially two of his five hypotheses as well as the guidance of these theories towards the teaching of business English reading for students majored in business English. 展开更多
关键词 S.D.Krashen LANGUAGE ACQUISITION theory hypotheses the TEACHING of BUSINESS English READING
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MULTITARGET STATE AND TRACK ESTIMATION FOR THE PROBABILITY HYPOTHESES DENSITY FILTER 被引量:3
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作者 Liu Weifeng Han Chongzhao +2 位作者 Lian Feng Xu Xiaobin Wen Chenglin 《Journal of Electronics(China)》 2009年第1期2-12,共11页
The particle Probability Hypotheses Density (particle-PHD) filter is a tractable approach for Random Finite Set (RFS) Bayes estimation, but the particle-PHD filter can not directly derive the target track. Most existi... The particle Probability Hypotheses Density (particle-PHD) filter is a tractable approach for Random Finite Set (RFS) Bayes estimation, but the particle-PHD filter can not directly derive the target track. Most existing approaches combine the data association step to solve this problem. This paper proposes an algorithm which does not need the association step. Our basic ideal is based on the clustering algorithm of Finite Mixture Models (FMM). The intensity distribution is first derived by the particle-PHD filter, and then the clustering algorithm is applied to estimate the multitarget states and tracks jointly. The clustering process includes two steps: the prediction and update. The key to the proposed algorithm is to use the prediction as the initial points and the convergent points as the es- timates. Besides, Expectation-Maximization (EM) and Markov Chain Monte Carlo (MCMC) ap- proaches are used for the FMM parameter estimation. 展开更多
关键词 Probability hypotheses Density (PHD) Particle-PHD filter State and track estimation Finite mixture models
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Analysis of Krashen's Affective Filter Hypothesis
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作者 赵静 《海外英语》 2011年第8X期281-283,共3页
Affective filter hypothesis is one of Krashen's five hypotheses on Second Language Acquisition (SLA), and it states that a number of affective variables play a very important role in Second Language Acquisition. B... Affective filter hypothesis is one of Krashen's five hypotheses on Second Language Acquisition (SLA), and it states that a number of affective variables play a very important role in Second Language Acquisition. Based on the introduction of affective filter hypothesis, this paper will analyze the significance and shortcomings of this hypothesis. 展开更多
关键词 Krashen’s five hypotheses AFFECTIVE filter HYPOTHESIS SIGNIFICANCE and SHORTCOMINGS
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Limited negative semantics based inductive hypotheses
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作者 叶风 王亚东 +1 位作者 徐晓飞 权光日 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 1999年第3期5-9,共5页
The Learning method of inductive logic programming evaluates the the quality of inductive hypotheses commonlyby how well the hypotheses cover training examples extensionally. Ths kind of evalution will be completely i... The Learning method of inductive logic programming evaluates the the quality of inductive hypotheses commonlyby how well the hypotheses cover training examples extensionally. Ths kind of evalution will be completely inapplica-ble to the situation where there are non-simple or noise examples. Based on Limited Negative semantics, This paperextends induction of simple examples to that of generalized ones and presents 3 criteria on accepting inductive hypothe-ses in order to fit for different goals of induction. The relation between inductive hypotheses and background knowledgeis also established in this Paper. The conclusions in this paper are helpful to implement learning algorithms and to ex-tend application fields of ILP. 展开更多
关键词 machine learning INDUCTIVE logic PROGRAMMING generalized EXAMPLES INDUCTIVE hypotheses
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Why It Is Problematic to Calculate Probabilities of Findings Given Range Null Hypotheses
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作者 David Trafimow 《Open Journal of Statistics》 2017年第3期483-499,共17页
An important problem with null hypothesis significance testing, as it is normally performed, is that it is uninformative to reject a point null hypothesis [1]. A way around this problem is to use range null hypotheses... An important problem with null hypothesis significance testing, as it is normally performed, is that it is uninformative to reject a point null hypothesis [1]. A way around this problem is to use range null hypotheses [2]. But the use of range null hypotheses also is problematic. Aside from the usual issues of whether null hypothesis significance tests can be justified at all, there is an issue that is specific to range null hypotheses. It is not straightforward how to calculate the probability of the data given a range null hypothesis. The traditional way is to use the single point that maximizes the obtained p-value. The Bayesian alternative is to propose a prior probability distribution and integrate across it. Because frequentists and Bayesians disagree about a variety of issues, especially those pertaining to whether it is permissible to assign probabilities to hypotheses, and what gets lost in the shuffle is that the two camps actually come to different answers for the probability of the data given a range null hypothesis. Because the probability of the data given the hypothesis is a precursor for both camps, for drawing conclusions about hypotheses, different values for this probability for the different camps is crucial but seldom acknowledged. The goal of the present article is to bring out the problem in a manner accessible to researchers without strong mathematical or statistical backgrounds. 展开更多
关键词 RANGE hypotheses One-Tailed Test RANGE NULL HYPOTHESIS Uninformative hypotheses
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Two Hypotheses of “Melanization” on Electrogalvanized Steel Surface
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作者 Ning LT, Derui ZHOU and Deyu LI Dept. of Applied Chemistry, Harbin Institute of Technology, Harbin 150001, China Kurachi Mitsuo Kyoto University, Kyoto 606-8283, Japan E-mail: liningt@ihw.com.cn 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2001年第3期343-345,共3页
Melanization is harmful to the lightness of galvanized steel surface and also reduces the bonding force between a paint coat and the steel sheet. Experimental results showed that the hypothesis of Zn-Pb codeposition d... Melanization is harmful to the lightness of galvanized steel surface and also reduces the bonding force between a paint coat and the steel sheet. Experimental results showed that the hypothesis of Zn-Pb codeposition does not hold true, while the fact that PbSO4 micelles in sulfate bath settle on the coating surface support the second hypothesis. The authors come to the conclusions that (1) Any measure to eliminate PbSO4 micelles before or after passivation of the coating will prevent melanization; (2) PbSO4 micelles adsorbed on the surface of passivated film promote the growth of oxygen-deficient Zn oxide and result in the generation of melanization. 展开更多
关键词 Two hypotheses of MELANIZATION PB
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Sequential Test of Fuzzy Hypotheses
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作者 Mohammad Ghasem Akbari 《Open Journal of Statistics》 2011年第2期87-92,共6页
In testing statistical hypotheses, as in other statistical problems, we may be confronted with fuzzy concepts. This paper deals with the problem of testing hypotheses, when the hypotheses are fuzzy and the data are cr... In testing statistical hypotheses, as in other statistical problems, we may be confronted with fuzzy concepts. This paper deals with the problem of testing hypotheses, when the hypotheses are fuzzy and the data are crisp. We first give new definitions for notion of mass (density) probability function with fuzzy parameter, probability of type I and type II errors and then state and prove the sequential probability ratio test, on the basis of these new errors, for testing fuzzy hypotheses. Numerical examples are also provided to illustrate the approach. 展开更多
关键词 CANONICAL FUZZY Number FUZZY hypotheses Type I and II ERROR SIZES SEQUENTIAL PROBABILITY Ratio Test
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Consistent Criteria for checking Hypotheses
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作者 Laura Eliauri Malkhaz Mumladze Zurab Zerakidze 《Journal of Mathematics and System Science》 2013年第10期514-518,共5页
This paper we study a consistent criterion for checking Hypotheses. Given definition of consistent criterion for checking hypotheses for family probability measures which were defined by Z. Zerakidze (see 5). We pro... This paper we study a consistent criterion for checking Hypotheses. Given definition of consistent criterion for checking hypotheses for family probability measures which were defined by Z. Zerakidze (see 5). We prove the necessary and sufficient conditions are obtained for the existence of consistent criteria of hypotheses. For example we clearly build of a consistent criteria for checking hypotheses. 展开更多
关键词 Consistent criterion ORTHOGONAL SEPARABLE hypotheses.
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Hypotheses of "Harmonious Man": The Humanity Upgrade of Management and It's Sustainability Significance
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作者 SHunzhong XIA Guizhen YANG Yizhen WANG 《International English Education Research》 2015年第9期52-55,共4页
Hypotheses of humanity is the logical premise and foundation of institution design and perfect. "Political man" had boosted the sprout of ancient democracy polity, "economic man" has accelerated the development of... Hypotheses of humanity is the logical premise and foundation of institution design and perfect. "Political man" had boosted the sprout of ancient democracy polity, "economic man" has accelerated the development of market economy in immediate and modern times, "free man" described the blueprint of future society, and "harmonious man" will promote the construction of harmonious society and the development of management to conducting oneself so as to serve others. The article explains the theory headstream, abstract ways, basic intension and sustainability effect to the hypotheses of"harmonious man". 展开更多
关键词 humanity hypotheses harmonious man conducting oneself so as to serve others sustainability.
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Constrained Bayesian Method for Testing the Directional Hypotheses
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作者 Kartlos J. Kachiashvili N. K. Bansal I. A. Prangishvili 《Journal of Mathematics and System Science》 2018年第4期96-118,共23页
The paper discusses the generalization of constrained Bayesian method (CBM) for arbitrary loss functions and its application for testing the directional hypotheses. The problem is stated in terms of false and tru... The paper discusses the generalization of constrained Bayesian method (CBM) for arbitrary loss functions and its application for testing the directional hypotheses. The problem is stated in terms of false and true discovery rates. One more criterion of estimation of directional hypotheses tests quality, the Type III errors rate, is considered. The ratio among discovery rates and the Type III errors rate in CBM is considered. The advantage of CBM in comparison with Bayes and frequentist methods is theoretically proved and demonstrated by an example. 展开更多
关键词 CBM Bayesian test hypotheses testing false discovery rate type error rate.
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结构化分析方法应用的局限与反思 被引量:3
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作者 夏汇川 《情报理论与实践》 CSSCI 北大核心 2023年第6期79-85,54,共8页
[目的/意义]休厄提出的结构化分析方法是国外比较流行的一种情报研究方法并受到国内情报学界的广泛推介。然而,结构化分析方法在应用中存在的问题与局限却并未得到国内情报学者的足够重视。[方法/过程]介绍结构化分析方法的源起与发展,... [目的/意义]休厄提出的结构化分析方法是国外比较流行的一种情报研究方法并受到国内情报学界的广泛推介。然而,结构化分析方法在应用中存在的问题与局限却并未得到国内情报学者的足够重视。[方法/过程]介绍结构化分析方法的源起与发展,分析国内结构化分析方法相关研究的主题与局限,阐述结构化分析方法近年来在国外受到的诸多理论与实践上的质疑与批判。[结果/结论]情报研究方法的借鉴与运用不可脱离情报任务场景,而需因地制宜、因人而异。我国情报工作者应注意避免对国外流行的情报研究方法如结构化分析方法的简单照搬,应当重视针对具体的情报任务场景运用合适的分析工具,探索并构建符合国情和专业领域情报工作特点与要求的情报研究方法。 展开更多
关键词 结构化分析 竞争性假设分析 情报分析 众包模式
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Reasons for Modern Warming:Hypotheses and Facts
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作者 Nikolai Nikolaevich Zavalishin 《Journal of Atmospheric Science Research》 2022年第1期11-17,共7页
Two hypotheses of modern warming are considered:natural and anthro­pogenic.The probabilities of each of them are compared.It is proved that the hypothesis of natural warming is much more likely than the hypothesi... Two hypotheses of modern warming are considered:natural and anthro­pogenic.The probabilities of each of them are compared.It is proved that the hypothesis of natural warming is much more likely than the hypothesis of anthropogenic warming.It is shown that the displacement of the Sun from the center of mass of the solar system directly affects the temperature of the surface atmosphere in the synoptic regions of Eurasia.This result corresponds to the model of E.P.Borysenkov with variations of the solar constant or,equivalently,with variations of the Bond albedo. 展开更多
关键词 hypotheses NATURAL ANTHROPOGENIC Temperature Lower atmosphere ALBEDO Solar displacement
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基于分层贝叶斯模型的图像修复方法 被引量:1
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作者 苏挺超 沈映珊 《计算机应用与软件》 北大核心 2023年第10期261-267,共7页
针对当前图像修复方法存在的运算复杂、修复后图像质量下降等问题,提出一种基于分层贝叶斯模型的图像修复方法,在高斯先验假设的基础上,利用Gaussian-Wishart分布对均值和协方差矩阵的概率分布进行建模,将问题正则化的同时提升参数估计... 针对当前图像修复方法存在的运算复杂、修复后图像质量下降等问题,提出一种基于分层贝叶斯模型的图像修复方法,在高斯先验假设的基础上,利用Gaussian-Wishart分布对均值和协方差矩阵的概率分布进行建模,将问题正则化的同时提升参数估计的稳定性,采用变分贝叶斯期望最大(Variational Bayesian Expectation Maximum,VBEM)算法对模型进行求解,得到最小均方误差准则下的最优重构。结果表明,该算法在图像修复时间、峰值信噪比和结构相似度等方面相对于对比方法均有较为明显提升,具有较高的应用前景。 展开更多
关键词 图像修复 像素缺失 分层贝叶斯 先验假设
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目标跨像元展宽“分裂”退化模型与检测研究
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作者 何青叶 林长青 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2023年第3期391-398,共8页
采用大规模红外探测器的遥感仪器对以恒星为主的点目标成像时,受点目标跨像元效应、探测器读出带宽不足等影响,目标信号展宽,在多抽头间隔采样下出现“分裂点”现象,空间红外遥感仪器定位精度、目标辨识能力下降。针对此问题,本文构建... 采用大规模红外探测器的遥感仪器对以恒星为主的点目标成像时,受点目标跨像元效应、探测器读出带宽不足等影响,目标信号展宽,在多抽头间隔采样下出现“分裂点”现象,空间红外遥感仪器定位精度、目标辨识能力下降。针对此问题,本文构建了点目标“分裂”退化模型,并根据分裂点之间的强相关性,设计了预检测-能量维度迭代-模型更新-后检测的目标检测流程,通过形态学滤波与多假设关联跟踪对“分裂点”目标各观测进行独立跟踪,获取“分裂点”统计信息。然后利用已知恒星成像的质心矫正退化模型并映射到检测图像,修正目标质心。测试结果表明,该方法能有效区分多目标和“分裂点”造成的假目标,平均定位精度由0.5像元以上提升到0.15像元内。 展开更多
关键词 “:分裂点”目标 退化模型 多假设关联跟踪 质心校正
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秘密与信息:保密科学的“三元问题”探秘——兼论中国特色保密科学理论体系的建构 被引量:1
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作者 王皓 《武汉理工大学学报(社会科学版)》 2023年第5期14-29,共16页
日益受到重视的保密学在中国是一门年轻学科和重要研究领域,其建设发展势头较好,但该学科“理论的困难”及其“元概念”“元问题”“元理论”(这三者以下统称“三元问题”)和原理规律规则等基础理论难题依然还在,且研究进展较小,难以适... 日益受到重视的保密学在中国是一门年轻学科和重要研究领域,其建设发展势头较好,但该学科“理论的困难”及其“元概念”“元问题”“元理论”(这三者以下统称“三元问题”)和原理规律规则等基础理论难题依然还在,且研究进展较小,难以适应保密科学和实践发展的迫切需要。针对保密学“理论的困难”及其缓解问题,从秘密与信息基本关系的宏观视角和总体研究维度来探讨保密科学最核心的基础理论问题,分析保密科学及其“三元问题”所涉及的最始源最基础的信息概念和信息科学问题以及所导致的当代中国“保密三难困境”,简要阐明“三元问题”的研究意义,秘密和保密同信息、情报、档案、传播四者之间的关系,得出保密科学及其“三元问题”的初步认识和各自界说。首次提出“保密科学基础理论框架”“三元问题”等范畴及其所属的“元概念”、“元理论”、“保密科学六元概念”、“保密六元纠缠性”、“信息隐显(隐释)性”、“保密公理”、“保密信仰(保密信念、保密信条)”、“保密核心价值观”等概念,以及“保密科学五大假说”、“保密科学五大公理”、“保密科学七大命题”、“保密科学双元机理”(保密科学第一原理)、“密战致胜基本规律(法则)”等命题、假说、公理、原理、规律、规则和论断,试图开启中国特色保密科学基础理论简要框架的艰难构筑新行程,并为建设初级阶段的中国特色保密科学理论大厦夯实根基、添砖加瓦。 展开更多
关键词 保密科学 元概念 元问题 元理论 五大假说 五大公理 七大命题 第一原理
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物种多样性与生态系统功能:影响机制及有关假说 被引量:109
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作者 黄建辉 白永飞 韩兴国 《生物多样性》 CAS CSCD 2001年第1期1-7,共7页
本文主要介绍了有关物种多样性对生态系统功能的影响机制及有关假说 ,包括冗余种假说、铆钉假说、不确定假说、无效假说、补偿 /关键种假说、非线性假说、单调 /驼峰模型假说等。尽管这些假说的提出都有一定的理论或实验研究基础 ,但到... 本文主要介绍了有关物种多样性对生态系统功能的影响机制及有关假说 ,包括冗余种假说、铆钉假说、不确定假说、无效假说、补偿 /关键种假说、非线性假说、单调 /驼峰模型假说等。尽管这些假说的提出都有一定的理论或实验研究基础 ,但到目前为止 ,还没有一种假说被普遍认为反映了两者之间关系的实际情形 (如果确实存在这样一种普适机制 )。通过分析 ,我们发现在这些假说之间存在一定的内在联系 ,它们或者互相包含 ,或者互相补充 。 展开更多
关键词 生态系统功能 物种多样性 假说 影响机制
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