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   9865篇
  免费   342篇
  国内免费   27篇
化学   5244篇
晶体学   81篇
力学   230篇
数学   2153篇
物理学   2526篇
  2022年   73篇
  2021年   118篇
  2020年   153篇
  2019年   155篇
  2018年   187篇
  2017年   192篇
  2016年   397篇
  2015年   361篇
  2014年   397篇
  2013年   691篇
  2012年   529篇
  2011年   631篇
  2010年   390篇
  2009年   329篇
  2008年   396篇
  2007年   362篇
  2006年   287篇
  2005年   161篇
  2004年   203篇
  2003年   168篇
  2002年   165篇
  2001年   129篇
  2000年   137篇
  1999年   131篇
  1998年   120篇
  1997年   109篇
  1996年   115篇
  1995年   87篇
  1994年   97篇
  1993年   92篇
  1992年   97篇
  1991年   77篇
  1990年   99篇
  1989年   84篇
  1988年   80篇
  1987年   79篇
  1985年   104篇
  1984年   110篇
  1983年   79篇
  1982年   91篇
  1981年   97篇
  1980年   83篇
  1979年   99篇
  1978年   90篇
  1977年   82篇
  1976年   105篇
  1975年   93篇
  1974年   94篇
  1973年   74篇
  1968年   76篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Journal of Solid State Electrochemistry - The addition of nanocrystalline titanium dioxide (P90) to a cathode of Li/S cell enhances its voltammetric charge capacity by 19%, from which only a small...  相似文献   
2.
Czechoslovak Mathematical Journal - We give a complete characterization of closed sets F ? ?2 whose distance function dF:= dist(·, F) is DC (i.e., is the difference of two convex...  相似文献   
3.
This review summarizes recent progress in understanding the oxygen reduction and evolution reactions at the lanthanum strontium manganite electrode of a high-temperature solid oxide cell. Information provided here is put into the perspective of the defect chemistry of lanthanum strontium manganite and its impact on the electrode reaction mechanisms itself. After summarizing recent views on the oxygen reduction reaction mechanism, the focus turns to the oxygen evolution reaction, which is significantly less treated in the literature. A combination of the information in the literature on both reactions was the basis for modified reaction mechanism of the oxygen evolution reaction to be proposed under consideration of recent experimental observations and theoretical findings.  相似文献   
4.
Lithuanian Mathematical Journal - We examine the variance of a linear statistic defined on the symmetric group endowed with the Ewens probability. Despite the dependence of the summands, it can be...  相似文献   
5.
Central European Journal of Operations Research - Digital competences are among the most important competences in modern society, with the education system playing a key role in the acquisition of...  相似文献   
6.
Siberian Mathematical Journal - Under consideration is a Dirichlet series depending on a parameter and absolutely convergent in the right half of the critical strip. We prove that...  相似文献   
7.
Laurinčikas  A. 《Mathematical Notes》2022,111(3-4):571-578
Mathematical Notes - In 2007, H. Mishou proved the universality theorem on the joint approximation of a pair of analytic functions by the shifts $$(\zeta(s+i\tau),\zeta(s+i\tau,\alpha))$$ of the...  相似文献   
8.
Journal of Algebraic Combinatorics - In this paper we exploit a relationship between certain pairwise balanced designs with v points and periodic Golay pairs of length v, to classify periodic Golay...  相似文献   
9.
Lithuanian Mathematical Journal - In this paper, we consider estimation of unknown parameters of the tapered Pareto distribution, which belongs to the class of semiheavy distributions, by a sample...  相似文献   
10.
A series of dinuclear half-sandwich Ru(II), Os(II) and Ir(III) complexes [Ru2(μ-Ln)(η6-pcym)2Cl2](PF6)2 ( 1 , 4 ), [Os2(μ-Ln)(η6-pcym)2Cl2](PF6)2 ( 2 , 5 ) and [Ir2(μ-Ln)(η5-Cp*)2Cl2](PF6)2 ( 3 , 6 ), based on 4,4′-biphenyl-based bridging Schiff base ligands N,N′-(biphenyl-4,4′-diyldimethylidyne)bis-2-(pyridin-2-yl)methanamine (L1; for 1 – 3 ) and N,N′-(biphenyl-4,4′-diyldimethylidyne)bis-2-(pyridin-2-yl)ethanamine (L2; for 4 – 6 ) is reported; pcym = 1-methyl-4-(propan-2-yl)benzene, Cp* = pentamethylcyclopentadienyl. The complexes were characterized by relevant analytical techniques (i.e. elemental analysis, FT-IR, NMR, ESI-MS), and their in vitro cytotoxicity was assessed at six cancerous and two non-cancerous (healthy) human cell lines. Overall, complexes 4 – 6 , containing the L2 bridging ligand, revealed higher cytotoxicity as compared with 1 – 3 and, thus, they were studied in greater detail. The best-performing complex 6 exceeded at least twice the in vitro cytotoxicity of cisplatin and showed high selectivity towards the cancer cells over the normal ones, including the primary culture of human hepatocytes. In contrast to cisplatin, complexes 4 – 6 did not induce the cell cycle modification of the treated A2780 human ovarian carcinoma cells (studied by flow cytometry and Western blot analysis). High levels of superoxide anion were induced by complexes 4 – 6 at the A2780 cells. The levels of activated forms of Caspase-3 and Caspase-8 at the A2780 cells treated by Ru(II) complex 4 were comparable with cisplatin, while complexes 5 and 6 had only a minor effect on activation of these caspases.  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