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   375220篇
  免费   1942篇
  国内免费   706篇
化学   160996篇
晶体学   5421篇
力学   23562篇
综合类   3篇
数学   73758篇
物理学   114128篇
  2021年   3130篇
  2020年   3456篇
  2019年   4217篇
  2018年   16412篇
  2017年   16354篇
  2016年   13871篇
  2015年   4362篇
  2014年   7191篇
  2013年   12506篇
  2012年   13840篇
  2011年   21998篇
  2010年   15492篇
  2009年   16056篇
  2008年   17912篇
  2007年   19756篇
  2006年   10271篇
  2005年   9942篇
  2004年   9899篇
  2003年   9757篇
  2002年   9091篇
  2001年   7928篇
  2000年   6361篇
  1999年   4658篇
  1998年   4459篇
  1997年   4296篇
  1996年   3973篇
  1995年   3437篇
  1994年   3469篇
  1993年   3492篇
  1992年   3466篇
  1991年   3874篇
  1990年   3857篇
  1989年   3880篇
  1988年   3620篇
  1987年   3704篇
  1986年   3400篇
  1985年   3917篇
  1984年   4149篇
  1983年   3549篇
  1982年   3756篇
  1981年   3425篇
  1980年   3201篇
  1979年   3683篇
  1978年   3736篇
  1977年   3890篇
  1976年   3957篇
  1975年   3699篇
  1974年   3544篇
  1973年   3728篇
  1972年   3199篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
141.
Davidovich  M. V. 《JETP Letters》2019,109(7):472-477

The elastic moduli of bilayer graphene nanomeshes, i.e., nanomeshes of bilayer graphene, where layers at the edges of “closed” holes are coupled to each other by a continuous network of sp2-hybridized atoms, have been calculated by ab initio methods. Structures with different configurations of holes in layers with AA, AB, and 30° stackings have been studied. It has been shown that the ultimate tensile strength of the nanomeshes under consideration is higher than that of graphene nanostructures and is comparable with the ultimate tensile strength of bilayer graphene and single-layer carbon nanotubes. A possible application of such strong nanomeshes as nanocontainers for hydrogen storage and other compressed gases has been also discussed.

  相似文献   
142.
Sukhorukova  O. S.  Tarasenko  A. S.  Tarasenko  S. V.  Shavrov  V. G. 《JETP Letters》2020,112(7):420-427
JETP Letters - At the resonant passage of a plane elastic shear wave through an acoustically continuous heterostructure consisting of magnetic and nonmagnetic layers in a symmetric nonmagnetic...  相似文献   
143.
144.
Optics and Spectroscopy - The transmission of intrinsic, antimony-doped, and gallium-doped Ge single crystals in the THz spectral range have been experimentally investigated. It is shown that the...  相似文献   
145.
The accumulated knowledge regarding molecular architectures is based on established, reliable, and accessible analytical tools that provide robust structural and functional information on assemblies. However, both the dynamicity and low population of noncovalently interacting moieties within studied molecular systems limit the efficiency and accuracy of traditional methods. Herein, the use of a saturation transfer-based NMR approach to study the dynamic binding characteristics of an anion to a series of synthetic receptors derived from bambusuril macrocycles is demonstrated. The exchange rates of BF4 are mediated by the side chains on the receptor (100 s−1<kex<5000 s−1), which play a critical role in receptor-anion binding dynamics. The signal amplification obtained with this approach allows for the identification of different types of intermolecular interactions between the receptor and the anion, something that could not have been detected by techniques hitherto used to study molecular assemblies. These findings, which are supported by a computational molecular dynamic study, demonstrate the uniqueness and added value of this NMR method.  相似文献   
146.
147.
148.
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method.  相似文献   
149.
Russian Chemical Bulletin - Terminal disaccharide fragment of phenolic glycolipid from Mycobacterium leprae (PGL-I) was synthesized as a glycoside with 4-(2-aminoethoxy)phenyl aglycon. The obtained...  相似文献   
150.
International Applied Mechanics - Problems of parametric optimization of rod structure stated in terms of the nonlinear programming problem are considered. Use is made of the method of projection...  相似文献   
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