多选题The intensive work of materials scientists and solid-state physicists
has given rise to a class of solids known as amorphous metallic alloys, or
glassy metals. There is a growing interest among theoretical and applied
researchers alike in the structural properties of these materials.
When a molten metal or metallic alloy is cooled to a solid, a crystalline
structure is formed that depends on the particular alloy composition. In
contrast, molten nonmetallic glass-forming materials, when cooled, do not assume
a crystalline structure, but instead retain a structure somewhat like that of
the liquid—an amorphous structure. At room temperature, the natural long-term
tendency for both types of materials is to assume the crystalline structure. The
difference between the two is in the kinetics or rate of formation of the
crystalline structure, which is controlled by factors such as the nature of the
chemical bonding and the ease with which atoms move relative to each other.
Thus, in metals, the kinetics favors rapid formation of a crystalline structure,
whereas in nonmetallic glasses the rate of formation is so slow that almost any
cooling rate is sufficient to result in an amorphous structure. For glassy
metals to be formed, the molten metal must be cooled extremely rapidly so that
crystallization is suppressed. The structure of glassy metals
is thought to be similar to that of liquid metals. One of the first attempts to
model the structure of a liquid was that by the late J.D. Bernal of the
University of London, who packed hard spheres into a rubber vessel in such a way
as to obtain the maximum possible density. The resulting dense, random-packed
structure was the basis for many attempts to model the structure of glassy
metals. Calculations of the density of alloys based on Bernal-type models of the
alloys metal component agreed fairly well with the experimentally determined
values from measurements on alloys consisting of a noble metal together with a
metalloid, such as alloys of palladium and silicon, or alloys consisting of
iron, phosphorus, and carbon, although small discrepancies remained. One
difference between real alloys and the hard spheres used in Bernal models is
that the components of an alloy have different sizes, so that models based on
two sizes of spheres are more appropriate for a binary alloy, for example, the
smaller metalloid atoms of the alloy might fit into holes in the dense,
random-packed structure of the larger metal atoms. One of the
most promising properties of glassy metals is their high strength combined with
high malleability. In usual crystalline materials, one finds an inverse relation
between the two properties, whereas for many practical applications simultaneous
presence of both properties is desirable. {{U}}One residual obstacle to practical
applications that is likely to be overcome is the fact that glassy metals will
crystallize at relatively low temperatures when heated slightly.{{/U}}
The author's attitude toward the prospects for the economic utilization
of glassy metals is one of ______.
A. disinterest
B. impatience
C. optimism
D. apprehension
E. skepticism
多选题Halle Berry"s portrayal of Dorothy Dandridge is a powerful ______: it calls forth the qualities that made Dandridge a legend.
多选题The university"s aggressive transformation from a teaching-centered college to a major research institution has brought ______ that teaching is now being ______.
多选题Although the administration repeatedly threatened to use its authority in order to ______ the student protestors into submission, they refused to be intimidated.
多选题In order to ______ the lose of natural wetlands used by mig rating snow geese, conservationists in the 1960"s and 1970"s ______ wetland refuges in the northern prairies.
多选题Although condemned by the review panel, to film critic Pauline Kael the movie seemed entirely ______ and unlikely to offend.
多选题Some teachers worry that history courses will become ______ for students due to curricular pressures that are ______ the subject.
多选题The deterioration of the ozone layer is ______, with the loss of penguin habitats being just one of the ______ results.
多选题Keats"s poetry was called ______ by those critics who noted that he indulged in sensuous imagery and luxuriant diction.
多选题Thomas Hardy"s novels are described as ______ because of their preoccupation with daily life in rural and agricultural settings.
多选题The instructor"s voice was so ______ that most students preferred taking a test over listening to its grating sound.
多选题Not only was the science of Hildegard of Bingen ______ her theology, but her religious visions helped give her scientific works ______ by winning her the support of medieval church authorities.
多选题"Foamy" viruses cause cells cultured in laboratories to swell but produce no such ______ in cells of living organism.
多选题When limitations were in effect on nuclear-arms testing, people tended
to save more of their money, but when nuclear-arms testing increased, people
tended to spend more of their money. The perceived threat of nuclear
catastrophe, therefore, decreases the willingness of people to postpone
consumption for the sake of saving money. The argument above
assumes that
A. the perceived threat of nuclear catastrophe has increased over the
years.
B. most people supported the development of nuclear arms.
C. people's perception of the threat of nuclear catastrophe depends on the
amount of nuclear-arms testing being done.
D. the people who saved the most money when nuclear-arms testing was limited
were the ones who supported such limitations.
E. there are more consumer goods available when nuclear-arms testing
increases.
多选题The general was so widely suspected of ______ during the war that his name eventually became synonymous with disloyalty.
多选题Displaying a heightened sense of ______, many of author Maria Cristina Mena"s characters exemplify a dignified and polite society.
多选题Isadora Duncan's masterly writings on the dance reveal the depth of her
determination to create a lyric form of the art which was free of
characterization, storytelling, and the theatrical exhibition of skills. She
wished to discard the traditional methods and established vocabularies of such
dance forms as ballet and to explore the internal sources of human
expressiveness. She shunned bodily ornamentation and strove to use only the
natural movements of her body, undistorted by acrobatic exaggeration and
stimulated only by internal compulsion. In her recitals Duncan danced to the
music of Beethoven, Wagner, and Gluck, among others, but, contrary to popular
belief, she made no attempt to visualize or to interpret {{U}}the music{{/U}};
rather, {{U}}she simply relied on it to provide the inspiration for expressing
inner feelings through movement.{{/U}} She did not regard this use of music as
ideal, however, believing that she would someday dispense with music entirely.
That day never came. The author implies that Duncan relied on
music in her recitals in order to
A. interpret musical works solely by means of natural body movements.
B. foster the illusion that music serves as an inspiration for the
dance.
C. inspire the expression of inner feeling when she danced.
D. validate the public belief that music inspires the expression of feeling
through movement.
E. counter the public belief that she made no attempt to visualize
music.
多选题Although he felt that Steven was ______, Mark did not sense that Steven"s ill will amounted to outright ______.
多选题Believing that scientists should ______ the public about important scientific issues, marine ecologist Jane Lubchenco has urged the research community to abandon its usual ______ in favor of more effective communication.
多选题Some Tibetan nomads used yak butter as a ______, one that often took the place of money in commercial transactions.