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排序方式: 共有898条查询结果,搜索用时 15 毫秒
41.
The Cardiothoracic Surgery Network is an international collaborative effort among cardiothoracic surgeons that provides a common platform for the exchange of information. The Cardiothoracic Surgery Network website provides peer-reviewed journals, multimedia applications, and a database repository. 相似文献
42.
43.
Karyotypes were prepared from peripheral blood leukocytes in 77 couples in whom there was no apparent cause for recurrent spontaneous abortion. In addition to conventional staining, chromosomes were stained by the new technics for Q-, G-, or C-banding. Translocations were found in 5 of 154 persons (3.25% or 1:31 individuals). The frequency of translocations in the general adult population is 0.4% (1:255). Two translocations were apparent only with the new technics for banding. The incidence of chromosomal microanomalies was 7.79% (2.6% in the general population). Karyotyping of couples with recurrent abortion is recommended, with use of the new staining technics. 相似文献
44.
Compared 151 employees in work groups with unstable membership to 582 employees in similar groups with stable membership. Contrary predictions concerning the effects of unstable membership were derived from the R. Likert and the W. G. Bennis conceptions of organization structure. Employees in unstable work groups reported less within-group peer leadership, but more favorable organizational context. Contrary to the prediction derived from Likert's theory, there were no differences on measures of group-referrent intervening variables and end-result variables, suggesting the viability of organic-adaptive structure described by Bennis. Increased lateral linkage among work groups of unstable membership is suggested as the mechanism that appears to compensate for the decreased peer leadership evident in unstable work groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
45.
DH Fine 《Canadian Metallurgical Quarterly》1980,37(4):199-202
The largest human exposure to N-nitrosamines is in the industrial section. Leather tanners are exposed to N-nitrosodimethylamine at levels up to 47 microgram/m3, corresponding to 440 microgram/person/day. Workers in the curing area of tire factories are exposed to N-nitrosomorpholine at levels up to 27 microgram/m3, corresponding to a intake of 250 microgram/person/day. These industrial exposures are considerably greater than exposure via foodstuffs, beer, cosmetics, cutting fluids and herbicides. 相似文献
46.
Initiation and growth of fatigue microcracks were investigated in several Nb and V alloyed high strength low alloy steels,
including conventional and dual phase microstructures. Fatigue microcracks initiated along prominent slip bands. Macrocracks
formed by linking up of small microcracks. At low applied stress or strain, the number of cycles to crack initiation increased
with the cyclic yield stress. Comparing the cyclic stress-strain curves to the monotonie stress-strain curves, cyclic hardening
or softening occurred, depending upon strain amplitude. Plateau regions were observed in plots of cyclic stress amplitudevs cyclic plastic strain amplitude obtained by increasing the total strain amplitude in steps after 30 cycles at each step.
In polycrystalline 0.03 pct Nb steel, the plateau region was identified with prominent slip band formation, as others have
observed in single crystals of copper, C-doped iron, and other metals. 相似文献
47.
The influence of red blood cell (RBC) aggregation on transparency of blood in the red-near infrared spectral range is investigated. We argue that for relatively thin blood layers the light diffraction on aggregates becomes the dominant phenomenon. The nature of pulsatile changes of blood transparency is explained by pulsations of RBC aggregate size. For another case of over-systolic vessel occlusion the following time evolution of blood transparency strongly depends on light wavelength. This dependence may serve as a basis for an alternative approach to noninvasive blood tests: occlusion spectroscopy. Theoretical results well correspond to both in vivo and in vitro measurements reproducing pulsatile blood flow and long occlusion as well. 相似文献
48.
One of the undisputed roles of the Internet is information spreading. However, to this day there is little understanding of the interaction between the way in which information is provided on the Internet and the behavior of different human personality types. This article focuses on the impact of the need for cognition on the desired level of interactivity of a given Website and on web surfing in general. For this experiment, four commercialized Websites were used: (1) flat with no hyperlinks and no time pressure; (2) flat with time pressure; (3) interactive1 with no time pressure; and (4) interactive with time pressure. All of the Websites contained identical information presented in different ways. The relations between need for cognition as a personality variable, time pressure as a situational stressor, the interactivity of the Web site, and several demographic variables were examined on Internet users’ behavior while surfing and on their preferences. One hundred and eighty-two experienced Web surfers took part in the experiment and were randomly assigned to one of the Websites. The number of hyperlinks used while surfing were counted by specially designed software. After surfing, the participants completed questionnaires regarding their satisfaction from the site, their willingness to return to the site, how persuasive the site was, and demographic data. It was predicted that people with high need for cognition would be more experienced in the Internet, use more hyperlinks, and stay longer in the site. People with a low need for cognition were predicted to prefer interactive over linear sites. Results support the preferences of people low in need for cognition of an interactive site. Other predictions were supported only partially. Implementations for Website design and further research are discussed. 相似文献
49.
Jianfeng Jiang Wenfeng Lo Peter Müller Noam D. Fine Myrium Maruani Alexander Raytman 《Inorganic chemistry communications》2009,12(6):527-529
fac-[FeII(CO)3X3]1? (X = Br, I) are synthesized and their structures have been determined. They are the first crystallographically characterized iron tricarbonyl trihalide complexes. fac-[FeII(CO)3X3]1? (X = Br, I) are fairly thermally stable and therefore lead themselves as excellent starting materials for the preparation of various iron carbonyl complexes since both the halide and carbonyl ligands are substitutionally labile. 相似文献
50.
The coarsening rates of both cubic and tetragonal Al3Zr precipitates in Al were measured. The tetragonal Al3Zr coarsened 16 times faster than the cubic modification in keeping with the fact that the latter is coherent and coplanar
with the matrix while the former forms a semicoherent interface with the matrix giving a larger interfacial energy. Partial
substitution of V for Zr reduced the precipitate-matrix mismatch for both phases and slowed both coarsening rates as well
as retarded the cubic to tetragonal transformation. Reducing strain and interfacial energy no doubt is the origin of this
effect. Since the cubic particles are spherical, their volume fraction is small, and the coherency strains are small, this
would appear to be an ideal system for testing the Lifshitz-Slyozov-Wagner theory of diffusion controlled Ostwald ripening.
While the theory seems to hold, the calculated diffusivity of Zr in Al is much higher than the value reported in the literature.
Because of the low coarsening rates of the dispersed particles, the Al-Zr-V system shows promise as the basis for a high temperature
Al alloy. 相似文献