5-1',1'-dimethylundecenyloxyphenylmethyl-11,17,23-tris-1 '',1 ''-dimethylethyl-25,26,27,28-tetrahydroxycalix[4] arene was synthesized from 1,1-dimethylundecenyoxylphenylmethylphenol (3) and bis...5-1',1'-dimethylundecenyloxyphenylmethyl-11,17,23-tris-1 '',1 ''-dimethylethyl-25,26,27,28-tetrahydroxycalix[4] arene was synthesized from 1,1-dimethylundecenyoxylphenylmethylphenol (3) and bishydroxymethylated p-tert-butylphenol-formaldehyde trimer (7) (3-[3-[3-(Hydroxymethyl)-tert-butylsalicyl-5]-tert-butylsalicy]-5-tert-butyl-2-hydroxybenzyl Alcohol) by '1+3' fragment condensation in dioxane with TiCl4 as condensation agent in 28% yield. It is the first long-chain monoalkenyl substituted calix[4]arene in which the alkenyl was attached to the upper rim of calix[4]arene.展开更多
Nowadays,the Chinese market is full of imported farming products,including products such as Thai rice,Vietnamese durian,Australian fresh meat.In the meantime,China’s special farming products also appear on the overse...Nowadays,the Chinese market is full of imported farming products,including products such as Thai rice,Vietnamese durian,Australian fresh meat.In the meantime,China’s special farming products also appear on the overseas dining table.Utilizing both the domestic and overseas markets and resources,China’s farming has展开更多
G. C. Ying, Y. Y. Meng, B. E. Sagan, and V. R. Vatter [1] found the maximum number of maximal independent sets in connected graphs which contain at most two cycles. In this paper, we give an alternative proof to deter...G. C. Ying, Y. Y. Meng, B. E. Sagan, and V. R. Vatter [1] found the maximum number of maximal independent sets in connected graphs which contain at most two cycles. In this paper, we give an alternative proof to determine the largest number of maximal independent sets among all connected graphs of order n ≥ 12, which contain at most two cycles. We also characterize the extremal graph achieving this maximum value.展开更多
Up to now, there are nearly 200 enterprises in China having passed the product certification of environmental protection, which is of national grade and involves thousands kinds of products. A commissioner of CNCA (Ce...Up to now, there are nearly 200 enterprises in China having passed the product certification of environmental protection, which is of national grade and involves thousands kinds of products. A commissioner of CNCA (Certification and Accreditation Administration of the People’ s Republic of China) introduced on Nov. 2nd, 2004, that the product certification of environmental protection, as the third party evaluation system, provided the market of environmental protection industry with unitary展开更多
It is reported from NRCCRM (the National Research Center for CRMs) that, China has presently developed 1262 kinds of grade A reference materials and 1739 grade B reference materials, involving the fields of the steel,...It is reported from NRCCRM (the National Research Center for CRMs) that, China has presently developed 1262 kinds of grade A reference materials and 1739 grade B reference materials, involving the fields of the steel, the geology, the petroleum, the nuclear material, the environment, the food and the clinical inspection,and etc. The reference materials play an important role in controlling the production quality, maintaining the market order and promoting the scientific and technological advancement.展开更多
A woman imperiously demanded a colonel s commission for her son.Speaking arrogantlyand endlessly,she told Lincoln,“Mr.President,you should know this.My grandfather foughtat Lexington,my father fought at New Orleans,a...A woman imperiously demanded a colonel s commission for her son.Speaking arrogantlyand endlessly,she told Lincoln,“Mr.President,you should know this.My grandfather foughtat Lexington,my father fought at New Orleans,and my husband laid down his life for our coun-try at Monterrey,so...”“Of course, I know this well, madam,”Lincoln interrupted the wom-展开更多
By using Schwarz alternating method, this paper presents asimplified alternating algorithm for the problems of two holes having arbitrary shapes and arrangements in an isotropic homogeneous linear elastic infinite reg...By using Schwarz alternating method, this paper presents asimplified alternating algorithm for the problems of two holes having arbitrary shapes and arrangements in an isotropic homogeneous linear elastic infinite region, and obtains stress and displacement fields for random times of iteration. After precision analysis it is found that the results for twenty times of iteration are of very high precision, and those with higher precision can be acquired if the iteration solving is further conducted. The comparison of the results from FEM further proves the reliability of the simplified alternating algorithm presented by this paper.展开更多
This paper argues that“the fear of having two sons”is a gender structure phenom-enon that causes anxiety for some Chinese families.To prove the existence of such a fear in some families,this paper considers three as...This paper argues that“the fear of having two sons”is a gender structure phenom-enon that causes anxiety for some Chinese families.To prove the existence of such a fear in some families,this paper considers three aspects:the ideal gender structure of children,women’s childbearing plan for second children and their actual child-bearing behavior.Data for nine provinces is taken from the China Fertility Survey of 2017.This paper finds that:(1)except for having no children,2 sons and 0 daughters is the most undesired gender structure;(2)among those who expect 1 son and 1 daughter,women whose first child is a son are less likely to plan to have a second child than those whose first child is a daughter;(3)among those who expect 1 son and 1 daughter,women with a son as the first child are less likely to have a second child than those with a daughter.These findings prove that,at present,the phenom-enon of the fear of having two sons does exist in some Chinese families.Finally,this paper summarizes how the attitudes of Chinese families towards having sons have changed since the 1950s from“a hope for having many sons”to“a desire for at least one son”and finally to“the fear of having two sons.”The paper also discusses the significance of the fear of having two sons phenomenon in terms of improving the proximate determinants of low fertility model.展开更多
Let the set of generalized polynomials having bounded coeffiicients be K={p=sum from j=1 to n α_j g_j α_j≤α_j≤β,j=1, 2,…, n}, where g_1, g_2,…, g_n are linearly independent continuous functions defined on thei...Let the set of generalized polynomials having bounded coeffiicients be K={p=sum from j=1 to n α_j g_j α_j≤α_j≤β,j=1, 2,…, n}, where g_1, g_2,…, g_n are linearly independent continuous functions defined on theinterval [a,b], α_j β_j are extended real numbers satisfying α_j<+∞, β_j>? andα_j≤β_j. Assumethat f is a continuous function defined on a compact set X [a, b]. This paper gives the characterizationtheorem for p being the best uniform approximation to f from K, and points out that the characteri-zation theorem can be applied in calculating the approximate solution of best approximation to f fromK.展开更多
IN this letter we discuss the necessary and sufficient condition of C^0 flows on closed surfaces with isolated singular points having the pseudo-orbit tracing property. According to ref. [1], on a closed surface, ever...IN this letter we discuss the necessary and sufficient condition of C^0 flows on closed surfaces with isolated singular points having the pseudo-orbit tracing property. According to ref. [1], on a closed surface, every minimal set of a C^r(r≥2) flow is trivial, but it is possible for a C^0 flow to contain non-trivial minimal sets. Thus C^0 flows on closed surfaces are more complicated than C^r(r≥2) flows.展开更多
It’s the hour of the evening to keep working on that report, clear the email inbox or set up social appointments for the weekend. You could also ease into the evening with
我一直是贵刊的热心读者。贵刊在1997年第7期发表了余皑媛选译的“Mom,I Want to Live with My Boyfriend”、作为一个“小女初长成”的母亲,我读了之后,久久不能平静,甚至还掉下了伤心的泪水。女儿在外地读大学,回来 度暑假,我同自己...我一直是贵刊的热心读者。贵刊在1997年第7期发表了余皑媛选译的“Mom,I Want to Live with My Boyfriend”、作为一个“小女初长成”的母亲,我读了之后,久久不能平静,甚至还掉下了伤心的泪水。女儿在外地读大学,回来 度暑假,我同自己的女儿促膝长谈,希望她从该文中记取有益的东西,让生活的风帆永远高高升起。今年第5期的《科技英语学习》又刊登了Rosemary Adang的“关于美国女学生未婚先孕的问题”的文章,我也浮想联翩,觉得中国和美国的国情大异,而中国人的许多传统美德是我们民族的源远流长的精神财富,我们应该永远继承和发扬下去。今日,我在Internet上读到了美国中学生的“性况”,惊讶之余,觉得文章信息丰富可靠。有必要让国人知道此真情。作为贵刊前两篇文章的续篇,我寄上加注的全文。望借贵刊一隅刊登。展开更多
XIE Youyu went to Antarctica in November, 1985. It was the second time that China sent a scientific expedition to the South Pole. On the eve of her Antarctic trip, my colleagues and I visited her. On behalf of all the...XIE Youyu went to Antarctica in November, 1985. It was the second time that China sent a scientific expedition to the South Pole. On the eve of her Antarctic trip, my colleagues and I visited her. On behalf of all the staffers of Women of China, we presented her with a flag bearing the words "Bring Credit to Our Country" and asked her to plant the flag at the South Pole which expressed our concern for China’s research in Antarctica, as well as our respect for Xie and her brave venture. Xie spent four months at展开更多
Let X be a compact subset of an interval [a, b] (a.b≥0), fa continuous function defined on X,and the set of algebraic polynomials having bounded coefficients.The paper gives an alternating characterization theorem of...Let X be a compact subset of an interval [a, b] (a.b≥0), fa continuous function defined on X,and the set of algebraic polynomials having bounded coefficients.The paper gives an alternating characterization theorem of a polynomial of best uniform approximation to f from K,and a de La Vallee-Poussin theorem.展开更多
Laozi’s concept of desire has rich ideological connotations,not only referring to reducing personal desires.Laozi’s concept of desire is based on“desire”as human nature,acknowledging the legitimacy and necessity o...Laozi’s concept of desire has rich ideological connotations,not only referring to reducing personal desires.Laozi’s concept of desire is based on“desire”as human nature,acknowledging the legitimacy and necessity of desire and demand.The rational criticism of“having desire”formed by“no desire”is the value pursuit of Laozi’s concept of desire.From both personal physical and mental aspects and social order,“no desire”plays an important guiding role.Nature is the essence of Laozi’s concept of desire,and being in harmony with nature is the best state of desire.Laozi’s concept of desire reveals a deep spirit of love,and the“ethics of love”highlights Laozi’s strong sense of care for the“other”and ethical attitude towards responsibility.Laozi’s contemplation of desire contains a strong humanistic spirit,with the aim of promoting the healthy and sustainable development of life and society.展开更多
文摘5-1',1'-dimethylundecenyloxyphenylmethyl-11,17,23-tris-1 '',1 ''-dimethylethyl-25,26,27,28-tetrahydroxycalix[4] arene was synthesized from 1,1-dimethylundecenyoxylphenylmethylphenol (3) and bishydroxymethylated p-tert-butylphenol-formaldehyde trimer (7) (3-[3-[3-(Hydroxymethyl)-tert-butylsalicyl-5]-tert-butylsalicy]-5-tert-butyl-2-hydroxybenzyl Alcohol) by '1+3' fragment condensation in dioxane with TiCl4 as condensation agent in 28% yield. It is the first long-chain monoalkenyl substituted calix[4]arene in which the alkenyl was attached to the upper rim of calix[4]arene.
文摘Nowadays,the Chinese market is full of imported farming products,including products such as Thai rice,Vietnamese durian,Australian fresh meat.In the meantime,China’s special farming products also appear on the overseas dining table.Utilizing both the domestic and overseas markets and resources,China’s farming has
文摘G. C. Ying, Y. Y. Meng, B. E. Sagan, and V. R. Vatter [1] found the maximum number of maximal independent sets in connected graphs which contain at most two cycles. In this paper, we give an alternative proof to determine the largest number of maximal independent sets among all connected graphs of order n ≥ 12, which contain at most two cycles. We also characterize the extremal graph achieving this maximum value.
文摘Up to now, there are nearly 200 enterprises in China having passed the product certification of environmental protection, which is of national grade and involves thousands kinds of products. A commissioner of CNCA (Certification and Accreditation Administration of the People’ s Republic of China) introduced on Nov. 2nd, 2004, that the product certification of environmental protection, as the third party evaluation system, provided the market of environmental protection industry with unitary
文摘It is reported from NRCCRM (the National Research Center for CRMs) that, China has presently developed 1262 kinds of grade A reference materials and 1739 grade B reference materials, involving the fields of the steel, the geology, the petroleum, the nuclear material, the environment, the food and the clinical inspection,and etc. The reference materials play an important role in controlling the production quality, maintaining the market order and promoting the scientific and technological advancement.
文摘A woman imperiously demanded a colonel s commission for her son.Speaking arrogantlyand endlessly,she told Lincoln,“Mr.President,you should know this.My grandfather foughtat Lexington,my father fought at New Orleans,and my husband laid down his life for our coun-try at Monterrey,so...”“Of course, I know this well, madam,”Lincoln interrupted the wom-
基金the National Natural Science Foundation of China (Grant No. 49772166).
文摘By using Schwarz alternating method, this paper presents asimplified alternating algorithm for the problems of two holes having arbitrary shapes and arrangements in an isotropic homogeneous linear elastic infinite region, and obtains stress and displacement fields for random times of iteration. After precision analysis it is found that the results for twenty times of iteration are of very high precision, and those with higher precision can be acquired if the iteration solving is further conducted. The comparison of the results from FEM further proves the reliability of the simplified alternating algorithm presented by this paper.
文摘This paper argues that“the fear of having two sons”is a gender structure phenom-enon that causes anxiety for some Chinese families.To prove the existence of such a fear in some families,this paper considers three aspects:the ideal gender structure of children,women’s childbearing plan for second children and their actual child-bearing behavior.Data for nine provinces is taken from the China Fertility Survey of 2017.This paper finds that:(1)except for having no children,2 sons and 0 daughters is the most undesired gender structure;(2)among those who expect 1 son and 1 daughter,women whose first child is a son are less likely to plan to have a second child than those whose first child is a daughter;(3)among those who expect 1 son and 1 daughter,women with a son as the first child are less likely to have a second child than those with a daughter.These findings prove that,at present,the phenom-enon of the fear of having two sons does exist in some Chinese families.Finally,this paper summarizes how the attitudes of Chinese families towards having sons have changed since the 1950s from“a hope for having many sons”to“a desire for at least one son”and finally to“the fear of having two sons.”The paper also discusses the significance of the fear of having two sons phenomenon in terms of improving the proximate determinants of low fertility model.
文摘Let the set of generalized polynomials having bounded coeffiicients be K={p=sum from j=1 to n α_j g_j α_j≤α_j≤β,j=1, 2,…, n}, where g_1, g_2,…, g_n are linearly independent continuous functions defined on theinterval [a,b], α_j β_j are extended real numbers satisfying α_j<+∞, β_j>? andα_j≤β_j. Assumethat f is a continuous function defined on a compact set X [a, b]. This paper gives the characterizationtheorem for p being the best uniform approximation to f from K, and points out that the characteri-zation theorem can be applied in calculating the approximate solution of best approximation to f fromK.
文摘IN this letter we discuss the necessary and sufficient condition of C^0 flows on closed surfaces with isolated singular points having the pseudo-orbit tracing property. According to ref. [1], on a closed surface, every minimal set of a C^r(r≥2) flow is trivial, but it is possible for a C^0 flow to contain non-trivial minimal sets. Thus C^0 flows on closed surfaces are more complicated than C^r(r≥2) flows.
文摘It’s the hour of the evening to keep working on that report, clear the email inbox or set up social appointments for the weekend. You could also ease into the evening with
文摘我一直是贵刊的热心读者。贵刊在1997年第7期发表了余皑媛选译的“Mom,I Want to Live with My Boyfriend”、作为一个“小女初长成”的母亲,我读了之后,久久不能平静,甚至还掉下了伤心的泪水。女儿在外地读大学,回来 度暑假,我同自己的女儿促膝长谈,希望她从该文中记取有益的东西,让生活的风帆永远高高升起。今年第5期的《科技英语学习》又刊登了Rosemary Adang的“关于美国女学生未婚先孕的问题”的文章,我也浮想联翩,觉得中国和美国的国情大异,而中国人的许多传统美德是我们民族的源远流长的精神财富,我们应该永远继承和发扬下去。今日,我在Internet上读到了美国中学生的“性况”,惊讶之余,觉得文章信息丰富可靠。有必要让国人知道此真情。作为贵刊前两篇文章的续篇,我寄上加注的全文。望借贵刊一隅刊登。
文摘XIE Youyu went to Antarctica in November, 1985. It was the second time that China sent a scientific expedition to the South Pole. On the eve of her Antarctic trip, my colleagues and I visited her. On behalf of all the staffers of Women of China, we presented her with a flag bearing the words "Bring Credit to Our Country" and asked her to plant the flag at the South Pole which expressed our concern for China’s research in Antarctica, as well as our respect for Xie and her brave venture. Xie spent four months at
文摘Let X be a compact subset of an interval [a, b] (a.b≥0), fa continuous function defined on X,and the set of algebraic polynomials having bounded coefficients.The paper gives an alternating characterization theorem of a polynomial of best uniform approximation to f from K,and a de La Vallee-Poussin theorem.
文摘Laozi’s concept of desire has rich ideological connotations,not only referring to reducing personal desires.Laozi’s concept of desire is based on“desire”as human nature,acknowledging the legitimacy and necessity of desire and demand.The rational criticism of“having desire”formed by“no desire”is the value pursuit of Laozi’s concept of desire.From both personal physical and mental aspects and social order,“no desire”plays an important guiding role.Nature is the essence of Laozi’s concept of desire,and being in harmony with nature is the best state of desire.Laozi’s concept of desire reveals a deep spirit of love,and the“ethics of love”highlights Laozi’s strong sense of care for the“other”and ethical attitude towards responsibility.Laozi’s contemplation of desire contains a strong humanistic spirit,with the aim of promoting the healthy and sustainable development of life and society.
