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   221148篇
  免费   2969篇
  国内免费   1335篇
化学   123076篇
晶体学   3065篇
力学   8889篇
综合类   61篇
数学   24485篇
物理学   65876篇
  2020年   1758篇
  2019年   1890篇
  2018年   2474篇
  2017年   2532篇
  2016年   3657篇
  2015年   2428篇
  2014年   3542篇
  2013年   8893篇
  2012年   7698篇
  2011年   9443篇
  2010年   6675篇
  2009年   6480篇
  2008年   8828篇
  2007年   8930篇
  2006年   8421篇
  2005年   7734篇
  2004年   6904篇
  2003年   6086篇
  2002年   6017篇
  2001年   6727篇
  2000年   5092篇
  1999年   3687篇
  1998年   3055篇
  1997年   3025篇
  1996年   3033篇
  1995年   2642篇
  1994年   2743篇
  1993年   2606篇
  1992年   2854篇
  1991年   2916篇
  1990年   2725篇
  1989年   2630篇
  1988年   2577篇
  1987年   2515篇
  1986年   2536篇
  1985年   3315篇
  1984年   3384篇
  1983年   2823篇
  1982年   3059篇
  1981年   2775篇
  1980年   2596篇
  1979年   2768篇
  1978年   2987篇
  1977年   3016篇
  1976年   3046篇
  1975年   2792篇
  1974年   2911篇
  1973年   2956篇
  1972年   2311篇
  1971年   1829篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Physics of the Solid State - Local internal stresses in two natural inhomogeneous materials differing in the structure have been calculated using analysis of pauses between acoustic emission...  相似文献   
12.
Crystallography Reports - Two LiInSe2 single crystals, grown under different conditions, have been studied. Characteristics of these crystals for neutron detection have been compared using...  相似文献   
13.
Journal of Radioanalytical and Nuclear Chemistry - In this paper a study for the selection of an NPE (nonylphenol ethoxylates)—free cocktail is discussed in order to be used for our routine...  相似文献   
14.
Radiophysics and Quantum Electronics - A well-known simplified model of turbulent convection from local sources of buoyancy and/or momentum acting for a short time has been developed and...  相似文献   
15.
Ukrainian Mathematical Journal - We establish new criteria of compatibility for a linear system of equations (equivalent to the Kronecker–Capelli theorem) or inequalities (equivalent to the...  相似文献   
16.
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   
17.
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   
18.
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   
19.
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   
20.
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   
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