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   1298758篇
  免费   30118篇
  国内免费   8003篇
化学   639698篇
晶体学   14232篇
力学   74110篇
综合类   148篇
数学   240934篇
物理学   367757篇
  2021年   12893篇
  2020年   16118篇
  2019年   16217篇
  2018年   12741篇
  2016年   28014篇
  2015年   20989篇
  2014年   30636篇
  2013年   74765篇
  2012年   37494篇
  2011年   34125篇
  2010年   37092篇
  2009年   39547篇
  2008年   33571篇
  2007年   29218篇
  2006年   35219篇
  2005年   27966篇
  2004年   29138篇
  2003年   27609篇
  2002年   26156篇
  2001年   25259篇
  2000年   21735篇
  1999年   19714篇
  1998年   18572篇
  1997年   19273篇
  1996年   19179篇
  1995年   18556篇
  1994年   18095篇
  1993年   17611篇
  1992年   17374篇
  1991年   17694篇
  1990年   16841篇
  1989年   16930篇
  1988年   16522篇
  1987年   16554篇
  1986年   15413篇
  1985年   21982篇
  1984年   23361篇
  1983年   19457篇
  1982年   21236篇
  1981年   20460篇
  1980年   19795篇
  1979年   20020篇
  1978年   21384篇
  1977年   20998篇
  1976年   20751篇
  1975年   19420篇
  1974年   19070篇
  1973年   19580篇
  1972年   14094篇
  1967年   12526篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
91.
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   
92.
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   
93.
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   
94.
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   
95.
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   
96.
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   
97.
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   
98.

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   
99.
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   
100.
JETP Letters - The results of the first run (December 2020) for the commissioning of the new superconducting synchrotron Booster at the Joint Institute for Nuclear Research are presented. Vacuum...  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