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   663428篇
  免费   7192篇
  国内免费   2514篇
化学   343067篇
晶体学   9476篇
力学   32123篇
综合类   78篇
数学   87099篇
物理学   201291篇
  2021年   5896篇
  2020年   6485篇
  2019年   7210篇
  2018年   9595篇
  2017年   9727篇
  2016年   13597篇
  2015年   7722篇
  2014年   12484篇
  2013年   29185篇
  2012年   23132篇
  2011年   27699篇
  2010年   20448篇
  2009年   20202篇
  2008年   26093篇
  2007年   25959篇
  2006年   23864篇
  2005年   21430篇
  2004年   19649篇
  2003年   17560篇
  2002年   17478篇
  2001年   18598篇
  2000年   14381篇
  1999年   11043篇
  1998年   9495篇
  1997年   9334篇
  1996年   8835篇
  1995年   7932篇
  1994年   7998篇
  1993年   7670篇
  1992年   8215篇
  1991年   8616篇
  1990年   8177篇
  1989年   8063篇
  1988年   7844篇
  1987年   7557篇
  1986年   7325篇
  1985年   9500篇
  1984年   9862篇
  1983年   8289篇
  1982年   8702篇
  1981年   8132篇
  1980年   7705篇
  1979年   8245篇
  1978年   8619篇
  1977年   8519篇
  1976年   8519篇
  1975年   8064篇
  1974年   7986篇
  1973年   8309篇
  1972年   6157篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Journal of Applied Mechanics and Technical Physics - Turbulent mixing at interfaces of three-layer gas systems after shock-wave passage has been studied. The influence of the initial roughness of...  相似文献   
62.
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   
63.
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   
64.
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   
65.
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   
66.
Crystallography Reports - Some questions related to the establishment, development, and prospects of physical studies using inelastic thermal-neutron scattering are briefly reviewed. The directions...  相似文献   
67.
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   
68.
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   
69.
70.
Journal of Applied and Industrial Mathematics - We study the problem of optimal location of the ambulance fleet at the base stations. The objective is to minimize the average waiting time for...  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