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   424141篇
  免费   5439篇
  国内免费   2141篇
化学   231812篇
晶体学   6343篇
力学   17600篇
综合类   63篇
数学   49284篇
物理学   126619篇
  2020年   3285篇
  2019年   3663篇
  2018年   4542篇
  2017年   4563篇
  2016年   6914篇
  2015年   4670篇
  2014年   6867篇
  2013年   18607篇
  2012年   14449篇
  2011年   17731篇
  2010年   12138篇
  2009年   11881篇
  2008年   16190篇
  2007年   16484篇
  2006年   15269篇
  2005年   14096篇
  2004年   12592篇
  2003年   11175篇
  2002年   11034篇
  2001年   12368篇
  2000年   9304篇
  1999年   7170篇
  1998年   6006篇
  1997年   5978篇
  1996年   5775篇
  1995年   5269篇
  1994年   5190篇
  1993年   5121篇
  1992年   5571篇
  1991年   5661篇
  1990年   5318篇
  1989年   5256篇
  1988年   5240篇
  1987年   5111篇
  1986年   4974篇
  1985年   6720篇
  1984年   6917篇
  1983年   5718篇
  1982年   6259篇
  1981年   5905篇
  1980年   5667篇
  1979年   5838篇
  1978年   6201篇
  1977年   6115篇
  1976年   6305篇
  1975年   5711篇
  1974年   5888篇
  1973年   6201篇
  1972年   4306篇
  1971年   3404篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
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   
22.
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   
23.
24.
25.
Theoretical and Mathematical Physics - We present a one-line closed-form expression for the three-parameter breather of the nonlinear Schrödinger equation. This provides an analytic proof of...  相似文献   
26.
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   
27.
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   
28.
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   
29.
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   
30.
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