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   1798篇
  免费   73篇
  国内免费   20篇
化学   967篇
晶体学   3篇
力学   80篇
数学   516篇
物理学   325篇
  2023年   13篇
  2022年   37篇
  2021年   66篇
  2020年   71篇
  2019年   64篇
  2018年   83篇
  2017年   63篇
  2016年   94篇
  2015年   47篇
  2014年   78篇
  2013年   133篇
  2012年   115篇
  2011年   113篇
  2010年   75篇
  2009年   64篇
  2008年   97篇
  2007年   79篇
  2006年   48篇
  2005年   53篇
  2004年   48篇
  2003年   40篇
  2002年   30篇
  2001年   12篇
  2000年   11篇
  1999年   16篇
  1998年   12篇
  1997年   17篇
  1996年   14篇
  1995年   21篇
  1994年   22篇
  1993年   16篇
  1992年   17篇
  1991年   13篇
  1990年   13篇
  1989年   14篇
  1987年   9篇
  1986年   8篇
  1985年   20篇
  1984年   13篇
  1982年   18篇
  1981年   13篇
  1980年   10篇
  1979年   11篇
  1978年   10篇
  1977年   11篇
  1976年   10篇
  1975年   9篇
  1974年   8篇
  1973年   8篇
  1972年   6篇
排序方式: 共有1891条查询结果,搜索用时 0 毫秒
1.
2.
A novel microfluidic droplet generator is proposed, which can control the droplet size through turning an integrated micrometer head with ease, and the size of the produced micro-droplet can be automatically and real-time monitored by an open-sourced software and off-the-shelf hardware.  相似文献   
3.
In this paper, we establish some criteria for boundedness, stability properties, and separation of solutions of autonomous nonlinear nabla Riemann-Liouville scalar fractional difference equations. To derive these results, we prove the variation of constants formula for nabla Riemann-Liouville fractional difference equations.  相似文献   
4.
The evaluation and interpretation of the behavior of construction materials under fire conditions have been complicated. Over the last few years, artificial intelligence (AI) has emerged as a reliable method to tackle this engineering problem. This review summarizes existing studies that applied AI to predict the fire performance of different construction materials (e.g., concrete, steel, timber, and composites). The prediction of the flame retardancy of some structural components such as beams, columns, slabs, and connections by utilizing AI-based models is also discussed. The end of this review offers insights on the advantages, existing challenges, and recommendations for the development of AI techniques used to evaluate the fire performance of construction materials and their flame retardancy. This review offers a comprehensive overview to researchers in the fields of fire engineering and material science, and it encourages them to explore and consider the use of AI in future research projects.  相似文献   
5.
Anh  Pham Ky  Vinh  Nguyen The 《Numerical Algorithms》2019,81(3):983-1001
Numerical Algorithms - In this paper, we introduce a self-adaptive inertial gradient projection algorithm for solving monotone or strongly pseudomonotone variational inequalities in real Hilbert...  相似文献   
6.
Necessary and sufficient conditions for qualitative properties of infinite dimensional linear programing problems such as solvability, duality, and complementary slackness conditions are studied in this article. As illustrations for the results, we investigate the parametric version of Gale’s example.  相似文献   
7.
In this work,the entropy functions of ideal quantum gases in a three-dimensional harmonic trap are analytically calculated using temperature as an explicit variable.Afterward,the applicability of the analytical formulas is validated by comparison with the numerical calculation.The results illustrate that the obtained functions could be applied for the whole temperature regime with a maximum relative deviation of less than 7.5%in the vicinity of the critical temperature Tcin the case of Bose gases.Meanwhile,for Fermi gases,although the analytical formula fits well at very low-and high-temperature regimes,it cannot be applied at temperature in the range[0.3-0.5]T_F,where T_F is the Fermi temperature.In addition,the consistency between our formulas and classical ones at significantly high temperatures is also discussed.  相似文献   
8.
Journal of Radioanalytical and Nuclear Chemistry - To keep the accredited category for the gamma spectrometry test in our laboratory, the efficiency curves of a HPGe detector for soil sample in...  相似文献   
9.
10.
Differential Equations - We consider compact difference schemes of approximation order $$4+2 $$ on a three-point spatial stencil for the Klein–Gordon equations with constant and variable...  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