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   465131篇
  免费   4338篇
  国内免费   1616篇
化学   229559篇
晶体学   6889篇
力学   23908篇
综合类   63篇
数学   63329篇
物理学   147337篇
  2020年   4645篇
  2019年   5393篇
  2018年   7672篇
  2017年   7868篇
  2016年   10313篇
  2015年   5354篇
  2014年   9352篇
  2013年   19041篇
  2012年   16026篇
  2011年   19170篇
  2010年   14864篇
  2009年   14856篇
  2008年   18229篇
  2007年   18043篇
  2006年   16529篇
  2005年   14675篇
  2004年   13670篇
  2003年   12402篇
  2002年   12540篇
  2001年   12920篇
  2000年   10030篇
  1999年   7391篇
  1998年   6605篇
  1997年   6473篇
  1996年   6091篇
  1995年   5351篇
  1994年   5505篇
  1993年   5389篇
  1992年   5637篇
  1991年   5997篇
  1990年   5804篇
  1989年   5718篇
  1988年   5457篇
  1987年   5399篇
  1986年   5177篇
  1985年   6443篇
  1984年   6693篇
  1983年   5670篇
  1982年   6011篇
  1981年   5575篇
  1980年   5152篇
  1979年   5765篇
  1978年   5972篇
  1977年   6140篇
  1976年   6257篇
  1975年   5798篇
  1974年   5736篇
  1973年   5944篇
  1972年   4825篇
  1971年   4161篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Chen  R. J.  Chen  W.  Kong  F. L. 《Analysis Mathematica》2022,48(1):19-28

Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.

  相似文献   
52.
Physics of the Solid State - The external factors which influence the ferromagnetic resonance (FMR) line width in bilayer (ferromagnet/antiferromagnet) exchange-biased systems are studied. The...  相似文献   
53.
A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample.  相似文献   
54.
Crystallography Reports - The orientation of grains and the special boundaries formed by them in multicrystalline silicon has been studied by electron backscattered diffraction. It is found that...  相似文献   
55.
Theoretical and Mathematical Physics - The fractional derivative method is used to take wave dispersion into account in the wave equation when describing the propagation of gravitational soliton...  相似文献   
56.
Crystallography Reports - Methods of coherent X-ray diffraction imaging of the spatial structure of noncrystalline objects and nanocrystals (nanostructures) are considered. Particular attention is...  相似文献   
57.
58.
Journal of Mathematical Chemistry - The analytical solutions of an asymmetric double well potential $$V(x)=a\, x^2-b\, x^3+c\, x^4$$ are found to be a triconfluent Heun function $$H_{T}(\alpha ,...  相似文献   
59.
60.
Physics of Particles and Nuclei Letters - When creating accelerators and storage-ring installations in a compact space, there is not always enough space for all the necessary magnet elements. In...  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