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   223915篇
  免费   42198篇
  国内免费   29816篇
化学   147427篇
晶体学   2577篇
力学   15432篇
综合类   1017篇
数学   28503篇
物理学   100973篇
  2024年   616篇
  2023年   3456篇
  2022年   4098篇
  2021年   5454篇
  2020年   6503篇
  2019年   6761篇
  2018年   6085篇
  2017年   6084篇
  2016年   8823篇
  2015年   8809篇
  2014年   10143篇
  2013年   14596篇
  2012年   16904篇
  2011年   18926篇
  2010年   17785篇
  2009年   17581篇
  2008年   12358篇
  2007年   11218篇
  2006年   10323篇
  2005年   9447篇
  2004年   8512篇
  2003年   6737篇
  2002年   6139篇
  2001年   6071篇
  2000年   4997篇
  1999年   5631篇
  1998年   4820篇
  1997年   4421篇
  1996年   4919篇
  1995年   4840篇
  1994年   4832篇
  1993年   4447篇
  1992年   3924篇
  1991年   3437篇
  1990年   2860篇
  1989年   2716篇
  1988年   2513篇
  1987年   1746篇
  1986年   1746篇
  1985年   1392篇
  1984年   1362篇
  1983年   643篇
  1982年   1130篇
  1981年   934篇
  1980年   914篇
  1979年   612篇
  1978年   618篇
  1977年   711篇
  1976年   1126篇
  1972年   576篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
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   
103.
The contribution of rheological properties and viscoelasticity of the interfacial adsorbed layer to the emulsification mechanism of enzymatic modified sugar beet pectin (SBP) was studied. The component content of each enzymatic modified pectin was lower than that of untreated SBP. Protein and ferulic acid decreased from 5.52% and 1.08% to 0.54% and 0.13%, respectively, resulting in a decrease in thermal stability, apparent viscosity, and molecular weight (Mw). The dynamic interfacial rheological properties showed that the interfacial pressure and modulus (E) decreased significantly with the decrease of functional groups (especially proteins), which also led to the bimodal distribution of particle size. These results indicated that the superior emulsification property of SBP is mainly determined by proteins, followed by ferulic acid, and the existence of other functional groups also promotes the emulsification property of SBP.  相似文献   
104.
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   
105.
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   
106.
107.
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   
108.
109.
110.
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