首页 | 官方网站   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   1394876篇
  免费   29884篇
  国内免费   7731篇
数理化   1432491篇
  2020年   16003篇
  2019年   16110篇
  2018年   16605篇
  2017年   15278篇
  2016年   29725篇
  2015年   21268篇
  2014年   30592篇
  2013年   74748篇
  2012年   42912篇
  2011年   44278篇
  2010年   40955篇
  2009年   42572篇
  2008年   42310篇
  2007年   39506篇
  2006年   40675篇
  2005年   36052篇
  2004年   35107篇
  2003年   31348篇
  2002年   28190篇
  2001年   29529篇
  2000年   24297篇
  1999年   20949篇
  1998年   19063篇
  1997年   19634篇
  1996年   19405篇
  1995年   18674篇
  1994年   18255篇
  1993年   17785篇
  1992年   17950篇
  1991年   18215篇
  1990年   17384篇
  1989年   17405篇
  1988年   17083篇
  1987年   17022篇
  1986年   15888篇
  1985年   22417篇
  1984年   23681篇
  1983年   19717篇
  1982年   21372篇
  1981年   20582篇
  1980年   19917篇
  1979年   20350篇
  1978年   21593篇
  1977年   21255篇
  1976年   21041篇
  1975年   19751篇
  1974年   19434篇
  1973年   19931篇
  1972年   14415篇
  1967年   12769篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Journal of Applied Mechanics and Technical Physics - The wear resistance of DI37-VI and EK80-VI steel is studied using a friction testing device. A sample made of high-carbon chromium-vanadium...  相似文献   
92.
Given a graph sequence denote by T3(Gn) the number of monochromatic triangles in a uniformly random coloring of the vertices of Gn with colors. In this paper we prove a central limit theorem (CLT) for T3(Gn) with explicit error rates, using a quantitative version of the martingale CLT. We then relate this error term to the well-known fourth-moment phenomenon, which, interestingly, holds only when the number of colors satisfies . We also show that the convergence of the fourth moment is necessary to obtain a Gaussian limit for any , which, together with the above result, implies that the fourth-moment condition characterizes the limiting normal distribution of T3(Gn), whenever . Finally, to illustrate the promise of our approach, we include an alternative proof of the CLT for the number of monochromatic edges, which provides quantitative rates for the results obtained in [7].  相似文献   
93.
Mathematical Notes - A system of new differential-geometric notions as the result of an analysis of the Trudinger–Wang inequalities is proposed. Their naturalness in multivariate analysis and...  相似文献   
94.
Theoretical and Mathematical Physics - This paper is devoted to tetrahedron maps, which are set-theoretical solutions of the Zamolodchikov tetrahedron equation. We construct a family of tetrahedron...  相似文献   
95.
Crystallography Reports - The three-dimensional structure of recombinant thermophilic ribokinase from Thermus speсies 2.9 was determined at 2.4 Å resolution using crystals, which were...  相似文献   
96.
Sun  J.  Yuan  H. 《Experimental Mechanics》2021,61(3):565-580
Experimental Mechanics - Temperature gradients significantly affect the material fatigue process. A reliable and robust test procedure is needed for quantifying the effects of temperature gradients...  相似文献   
97.
Journal of Applied Mechanics and Technical Physics - A self-equilibrated stress field for an incompressible sphere is constructed based on a non-Euclidean continuum model. The...  相似文献   
98.
International Journal of Theoretical Physics - The interaction between two modes quantized field and asymmetric two atoms represents one of the important quantum models to study the nonclassical...  相似文献   
99.

Organisations are concerned about measuring the performance of the product/service they deliver to their customers. In all types of organisations, if a proper performance assessment is to be developed, it should be measured in different dimensions. At University, the new study programs include the development and assessment of transversal competences due to their importance in enhancing the abilities and improving the employability of students. The achievement of transversal competences can be assessed in different levels/stages; for example, the 1st and 2nd years of a Bachelor’s degree; the 3rd and 4th years of a Bachelor’s degree and at Master’s level. The purpose of this paper is to integrate the research into performance management in organisations to develop an approach consisting of four components (a methodology, a solid and integrated performance management framework, graphical diagrams and quantitative techniques) to assess and manage the achievement of transversal competences through the different levels of study using a consolidated approach. The proposal uses the Analytic Network Process (ANP) to model dependences and feedback among the elements of the competences.

  相似文献   
100.
Acta Mathematica Hungarica - Minkowski’s classical existence theorem provides necessary and sufficient conditions for a Borel measure on the unit sphere of Euclidean space to be the surface...  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-23

京公网安备 11010802026262号