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   47486篇
  免费   15706篇
  国内免费   77篇
化学   56494篇
晶体学   53篇
力学   2071篇
数学   3027篇
物理学   1624篇
  2024年   373篇
  2023年   4087篇
  2022年   1457篇
  2021年   2494篇
  2020年   4641篇
  2019年   2325篇
  2018年   2292篇
  2017年   622篇
  2016年   5611篇
  2015年   5557篇
  2014年   4977篇
  2013年   5227篇
  2012年   3347篇
  2011年   1181篇
  2010年   3501篇
  2009年   3438篇
  2008年   1163篇
  2007年   891篇
  2006年   254篇
  2005年   268篇
  2004年   183篇
  2003年   163篇
  2002年   146篇
  1996年   109篇
  1995年   156篇
  1994年   100篇
  1993年   228篇
  1992年   107篇
  1988年   119篇
  1987年   102篇
  1985年   109篇
  1984年   115篇
  1983年   111篇
  1982年   136篇
  1981年   164篇
  1980年   199篇
  1979年   191篇
  1978年   191篇
  1977年   313篇
  1976年   364篇
  1975年   456篇
  1974年   471篇
  1973年   289篇
  1972年   372篇
  1971年   355篇
  1970年   543篇
  1969年   413篇
  1968年   457篇
  1967年   114篇
  1963年   112篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
The field of medicinal inorganic chemistry is rapidly advancing. In particular organometallic complexes have much potential as therapeutic and diagnostic agents. The carbon‐bound and other ligands allow the thermodynamic and kinetic reactivity of the metal ion to be controlled and also provide a scaffold for functionalization. The establishment of structure–activity relationships and elucidation of the speciation of complexes under conditions relevant to drug testing and formulation are crucial for the further development of promising medicinal applications of organometallic complexes. Specific examples involving the design of ruthenium and osmium arene complexes as anticancer agents are discussed.  相似文献   
34.
In this study, a genetically encoded bioluminescent indicator for ERK2 dimer was developed with the split Renilla luciferase complementation method, in which the formation of ERK2 dimer induces a spontaneous emission of bioluminescence in living cells. In response to extracellular stimuli, such as epidermal growth factor (EGF) or 17β‐estradiol (E2), extracellular signal‐regulated kinase 2 (ERK2) is phosphorylated by its upstream kinase MEK, and also phosphorylates its substrates in various regions of the cell, including the nucleus. Phosphorylated ERK2 is led to form its dimer, thereby transporting itself into the nucleus. We demonstrated with the indicator that stimulation with EGF or E2 induces the formation of ERK2 dimer in living MCF‐7 cells. The dynamics of this dimer formation was examined and discussed.  相似文献   
35.
The notion of weak attractive ligand–polymer interactions is introduced, and its potential application, importance, and conceptual links with “cooperative” ligand–substrate interactions are discussed. Synthetic models of weak attractive ligand–polymer interactions are described, in which intramolecular weak C? H???F? C interactions (the existence of which remains contentious) have been detected by NMR spectroscopy and neutron and X‐ray diffraction experiments. These C? H???F? C interactions carry important implications for the design of catalysts for olefin polymerization, because they provide support for the practical feasibility of ortho‐F???Hβ ligand–polymer contacts proposed for living Group 4 fluorinated phenoxyimine catalysts. The notion of weak attractive noncovalent interactions between an “active” ligand and the growing polymer chain is a novel concept in polyolefin catalysis.  相似文献   
36.
37.
38.
39.
There are consistently estimable parameters of interest whose semiparametric Fisher information vanishes at some points of the model in question. Here we investigate how bad this is for estimation.  相似文献   
40.
It is widely believed that evolutionary dynamics of artificial self‐replicators realized in cellular automata (CA) are limited in diversity and adaptation. Contrary to this view, we show that complex genetic evolution may occur within simple CA. The evolving self‐replicating loops (“evoloops”) we investigate exhibit significant diversity in macro‐scale morphologies and mutational biases, undergoing nontrivial genetic adaptation by maximizing colony density and enhancing sustainability against other species. Nonmutable subsequences enable genetic operations that alter fitness differentials and promote long‐term evolutionary exploration. These results demonstrate a unique example of genetic evolution hierarchically emerging from local interactions between elements much smaller than individual replicators. © 2004 Wiley Periodicals, Inc. Complexity 10: 33–39, 2004  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