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   114135篇
  免费   19471篇
  国内免费   11870篇
化学   78009篇
晶体学   1343篇
力学   7537篇
综合类   670篇
数学   13662篇
物理学   44255篇
  2024年   245篇
  2023年   2250篇
  2022年   2553篇
  2021年   3883篇
  2020年   4588篇
  2019年   4524篇
  2018年   3826篇
  2017年   3550篇
  2016年   5542篇
  2015年   5279篇
  2014年   6448篇
  2013年   8436篇
  2012年   10285篇
  2011年   10807篇
  2010年   7224篇
  2009年   6979篇
  2008年   7344篇
  2007年   6697篇
  2006年   6129篇
  2005年   5123篇
  2004年   3862篇
  2003年   3042篇
  2002年   2873篇
  2001年   2319篇
  2000年   2047篇
  1999年   2353篇
  1998年   2067篇
  1997年   1921篇
  1996年   2058篇
  1995年   1659篇
  1994年   1586篇
  1993年   1298篇
  1992年   1163篇
  1991年   1064篇
  1990年   862篇
  1989年   631篇
  1988年   521篇
  1987年   415篇
  1986年   402篇
  1985年   360篇
  1984年   267篇
  1983年   169篇
  1982年   159篇
  1981年   115篇
  1980年   78篇
  1979年   48篇
  1978年   40篇
  1976年   40篇
  1975年   35篇
  1974年   47篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
This study is concerned with a new,explicit approach by means of which forms of the large strain elastic potential for multiaxial rubberlike elasticity may be obtained based on data for a single deformation mode.As a departure from usual studies,here for the first time errors may be estimated and rendered minimal for all possible deformation modes and,furthermore,failure behavior may be incorporated.Numerical examples presented are in accurate agreement with Treloar's well-known data.  相似文献   
82.
Yin  Pengpeng  Liu  Chang  Wang  Ying  Guan  Lei  Chen  Xian  Xiong  Xuejia  Jin  Hongzhe 《Russian Journal of General Chemistry》2021,91(5):897-903
Russian Journal of General Chemistry - A dinuclear Tb complex, Tb2(H2L)3(phen)2 (1), and two similar N-donor coordination complexes, Fe(phen)3·HL (2), Fe(bipy)3·HL·5H2O (3) (Na2H2L =...  相似文献   
83.
Recently,the nested Mach–Zehnder interferometer[Phys.Rev.Lett.111,240402(2013)]was modified by adding Dove prisms in a paper[Quantum Stud.:Math.Found.2,255(2015)],and an interesting result is that,after the Dove prisms were inserted,a signal at the first mirror of the nested interferometer was obtained.But,according to the former original paper,the photons have never been present near that mirror.In this work,we interpret this result naturally by resorting to the three-path interference method.Moreover,we find that even though the photons have been somewhere,they can hide the trace of being there.  相似文献   
84.
Photoactivated chemotherapy (PACT) has appealing merits over traditional chemotherapy as well as photodynamic therapy (PDT) by virtue of its spatial and temporal control on drug activity and oxygen-independent mechanisms of action. However, the short photoactivation wavelengths, e.g., visible light–activated Ru(II)-based PACT agents, limit the clinical application severely. In this work, a facile construction of supramolecular nanoparticles from a poly(ethylene glycol) (PEG)-modified [Ru(dip)2(py-SO3)]+ (abbreviated as Ru-PEG, dip = 4,7-diphenyl-1,10-phenanthroline, py-SO3 = pyridine-2-sulfonate) and 1,3-phenylenebis(pyren-1-ylmethanone) (BP) is shown. While Ru-PEG may undergo photoinduced ligand dissociation and release anticancer species of [Ru(dip)2(H2O)2]2+, BP has extremely large two-photon absorption cross sections (δ2) in the NIR region and intense fluorescence over the wavelengths where Ru-PEG has strong absorption. Thus, two-photon excitation of BP followed by an efficient Förster resonance energy transfer (FRET) from BP to Ru-PEG may lead to a potent inactivation against cisplatin-resistant cancer cells and 3D multicellular tumor spheroids (MCTSs). The residue fluorescence of BP also allows the cellular uptake of the particles to be visualized. This work provides a universal and convenient strategy to realize theranostic PACT in the ideal phototherapeutic window of 650–900 nm.  相似文献   
85.
Wu  Xuze  Sun  Yu  Wang  Yu  Chen  Yu 《Nonlinear dynamics》2020,99(3):1937-1958
Nonlinear Dynamics - Oblique collisions are more likely to happen in the realistic translational joint with clearance, compared to the full front impacts. It can be a quite demanding task to...  相似文献   
86.
87.
A new approach has been developed to improve SO2 sorption by cyano‐containing ionic liquids (ILs) through tuning the basicity of ILs and cyano–sulfur interaction. Several kinds of cyano‐containing ILs with different basicity were designed, prepared, and used for SO2 capture. The interaction between these cyano‐containing ILs and SO2 was investigated by FTIR and NMR methods. Spectroscopic investigations and quantum chemical calculations showed that dramatic effects on SO2 capacity originate from the basicity of the ILs and enhanced cyano–sulfur interaction. Furthermore, the captured SO2 was easy to release by heating or bubbling N2 through the ILs. This efficient and reversible process, achieved by tuning the basicity of ILs, is an excellent alternative to current technologies for SO2 capture.  相似文献   
88.
89.
90.
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