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   2491篇
  免费   296篇
  国内免费   155篇
化学   1866篇
晶体学   23篇
力学   115篇
综合类   1篇
数学   238篇
物理学   699篇
  2024年   4篇
  2023年   96篇
  2022年   109篇
  2021年   116篇
  2020年   162篇
  2019年   172篇
  2018年   160篇
  2017年   113篇
  2016年   172篇
  2015年   165篇
  2014年   186篇
  2013年   236篇
  2012年   268篇
  2011年   252篇
  2010年   164篇
  2009年   125篇
  2008年   133篇
  2007年   110篇
  2006年   65篇
  2005年   35篇
  2004年   20篇
  2003年   11篇
  2002年   16篇
  2001年   5篇
  2000年   15篇
  1999年   7篇
  1998年   6篇
  1997年   2篇
  1996年   1篇
  1995年   2篇
  1993年   2篇
  1991年   2篇
  1990年   6篇
  1988年   1篇
  1986年   1篇
  1985年   2篇
排序方式: 共有2942条查询结果,搜索用时 31 毫秒
1.
Liang  Guiming  Huang  Yunbao  Li  Haiyan  Lin  Jingliang 《Nonlinear dynamics》2021,105(4):3393-3407
Nonlinear Dynamics - The modal truncation is usually used in the dynamic response analysis of flexible multibody systems, in which, appropriate selection of modal shapes is very critical to achieve...  相似文献   
2.
In recent years, with the improvement of people’s living standards, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in the world. In this paper, the metabolic disorders in Sprague Dawley (SD) rats were induced by a choline-deficient, l -amino acid–defined (CDAA) diet. The therapeutic effects of polyene phosphatidylcholine (PPC) and Babao Dan (BBD) on NAFLD were observed. Lipidomic analysis was performed using ultra-high-performance liquid chromatography-Orbitrap MS, and data analysis and lipid identification were performed using the software LipidSearch. Both PPC and BBD can reduce lipid accumulation in the liver and improve abnormal biochemical indicators in rats, including reduction of triglycerides, total cholesterol, alanine transaminase and aspartate transaminase in serum. In addition, lipids in rat serum were systematically analyzed by lipidomics. The lipidomic results showed that the most obvious lipids with abnormal metabolism in CDAA diet–induced rats were glycerides (triglycerides and diacylglycerols), phospholipids and cholesterol esters. Both BBD and PPC partly reversed the disturbance to lipids induced by the CDAA diet. PPC may be more effective than BBD in alleviating NAFLD because it has a better effect on inhibiting the abnormal accumulation of lipids and reducing the inflammatory reaction in the body.  相似文献   
3.
This work is concerned with the extension of the Jacobi spectral Galerkin method to a class of nonlinear fractional pantograph differential equations. First, the fractional differential equation is converted to a nonlinear Volterra integral equation with weakly singular kernel. Second, we analyze the existence and uniqueness of solutions for the obtained integral equation. Then, the Galerkin method is used for solving the equivalent integral equation. The error estimates for the proposed method are also investigated. Finally, illustrative examples are presented to confirm our theoretical analysis.  相似文献   
4.
Theoretical and Mathematical Physics - We apply the Riemann–Hilbert method to the generalized mixed nonlinear Schrödinger equation and obtain a new formula for an explicit $$N$$ -soliton...  相似文献   
5.
Journal of Radioanalytical and Nuclear Chemistry - In the present work the final products of coumarin radiation chemical transformation are investigated by chromatography. During radiolysis of...  相似文献   
6.
Li  S. K.  Huang  L. L.  Lv  Y. D.  Feng  H. D. 《Russian Journal of Organic Chemistry》2019,55(9):1432-1438
Russian Journal of Organic Chemistry - A rapid and efficient catalytic approach has been proposed for the synthesis of dimethyl 2-[2-(aryl-amino)but-3-en-1-yl]- and...  相似文献   
7.
Let C 4 be a cycle of order 4. Write e x ( n , n , n , C 4 ) for the maximum number of edges in a balanced 3‐partite graph whose vertex set consists of three parts, each has n vertices that have no subgraph isomorphic to C 4 . In this paper, we show that e x ( n , n , n , C 4 ) 3 2 n ( p + 1 ) , where n = p ( p ? 1 ) 2 and p is a prime number. Note that e x ( n , n , n , C 4 ) ( 3 2 2 + o ( 1 ) ) n 3 2 from Tait and Timmons's works. Since for every integer m , one can find a prime p such that m p ( 1 + o ( 1 ) ) m , we obtain that lim n e x ( n , n , n , C 4 ) 3 2 2 n 3 2 = 1 .  相似文献   
8.
Journal of Solid State Electrochemistry - In this work, we synthesized metal-organic framework Cu3(BTC)2 which was applied as the doping materials of anode electrodes in capacitive deionization...  相似文献   
9.
Lv  Jian  Xiao  Ze-Hao  Pang  Li-Ping 《Numerical Algorithms》2020,83(2):653-668
Numerical Algorithms - We propose a preconditioner to accelerate the convergence of the GMRES iterative method for solving the system of linear equations obtained from discretize-then-optimize...  相似文献   
10.
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