首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   104篇
  免费   5篇
化学   65篇
力学   2篇
数学   9篇
物理学   33篇
  2022年   5篇
  2021年   1篇
  2020年   3篇
  2018年   4篇
  2017年   2篇
  2016年   6篇
  2015年   1篇
  2014年   1篇
  2013年   10篇
  2012年   3篇
  2011年   3篇
  2010年   6篇
  2009年   4篇
  2008年   5篇
  2007年   8篇
  2006年   8篇
  2005年   8篇
  2004年   3篇
  2003年   4篇
  2002年   8篇
  1999年   1篇
  1997年   1篇
  1995年   2篇
  1992年   1篇
  1989年   2篇
  1988年   1篇
  1986年   2篇
  1983年   1篇
  1982年   1篇
  1975年   3篇
  1973年   1篇
排序方式: 共有109条查询结果,搜索用时 15 毫秒
31.
32.
Advanced composite materials aimed for construction of organic photovoltaic cells have been studied by atomic force microscopy (AFM). The composites are based on poly(3-hexylthiophene) (P3HT), [6,6]-phenyl C61-butyric acid methyl ester (PCBM) and two different chiral photosensitive liquid crystalline (LC) materials. The objective of the study was to examine the nanoscale morphology of the active layer without and after annealing at specific temperature. The preliminary results of AFM observation of the morphological changes done on the investigated composites revealed an increase in the surface ordering. The surface area ratio decreases for both studied composites, while the basic roughness parameters (Sa and Sq) have been found toughly dependent on the structure of the photosensitive LC dopant.  相似文献   
33.
Summary.  Most NMR-active nuclei found in the periodic table have a quadrupole moment. In combination with a nonsymmetric electron distribution a strong NMR-active interaction results, which very often overshadows the dipolar and scalar couplings. This article aims at reviewing how these interactions manifest themselves in quadrupolar NMR and how they can be exploited for resonance assignment and structure elucidation, in spite of the presence of a strong quadrupolar interaction. E-mail: alexej.jerschow@nyu.edu Received April 16, 2002; accepted May 15, 2002  相似文献   
34.
Several new binary liquid crystalline mixtures have been designed and their properties were studied by complementary methods. It has been shown that even both pure components used for the mixture design possess the ferroelectric behaviour; the induced antiferroelectric smectic phase has been detected for one of the prepared mixtures. The phase diagram has been constructed and the existence of the antiferroelectric phase was confirmed by switching time and dielectric spectroscopy measurements. Some of the resulted mixtures possess very high values of the tilt angle that reaches close below 45° degrees at saturation. Values of spontaneous polarisation were found within 50–200 nC/cm2 in dependence of the mixture’s composition. Due to specific properties, the obtained mixtures might be interesting for further design of multicomponent mixtures and formulation of the advanced nanocomposite systems.  相似文献   
35.
Several types of the chiral thiols with two aromatic rings have been synthesised and grafted on polybutadiene diols backbone. The resulting functional polymers possess the OH end groups for the possible preparation of liquid crystal ordered networks. The thermal and mesomorphic properties of the synthesised side-chain units and resulting polymers have been studied by polarising optical microscopy, differential scanning calorimetry and X-ray scattering. Some of the resulting polymers possess a mesomorphic behaviour. The effects of the side-chain structure, number of the chiral groups and density of grafting on the polybutadiene diols have been studied.  相似文献   
36.
Mixtures of cold bosonic atoms in optical lattices undergo demixing on different length scales with increasing interspecies repulsion. As a general rule, the stronger the intraspecies interactions, the shorter is this length scale. The wealth of phenomena is documented by illustrative examples on both superfluids and Mott insulators.  相似文献   
37.
Monitoring the sodium concentration in vivo using 23Na MRI can be an important tool for assessing the onset of tissue disorders. Practical clinical 23Na MRI methods furthermore often do not allow one to use sufficiently small voxel sizes such that only the tissue of interest is seen, but a large signal contamination can arise from sodium in synovial fluid. Here we demonstrate that applying an inversion recovery (IR) technique allows one to distinctly select either the cartilage-bound or the free sodium for visualization in an image. The results are validated both ex vivo and in vivo.  相似文献   
38.
The phosphorylation of N‐benzoyl‐2‐(1,3,3‐trimethyl‐2‐methyleneindoline)acetamide ( 2 ) and ω‐(3‐dimethylamino)benzoyl‐1,3,3‐trimethyl‐2‐methyleneindoline ( 6 ) with phosphorus(III) halides resulted in the formation of 2,3‐dihydro‐4H‐1,5,2‐oxazaphosphinin‐4‐one and 1,2‐dihydro‐3H‐phosphindol‐3‐one systems, respectively. The properties of the obtained compounds were studied. Further cyclization of 1,2‐dihydro‐3H‐phosphindol‐3‐one into dihydrophosphindolo[3,2‐c]pyrazole was carried out. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:23–28, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10060  相似文献   
39.
40.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号