全文获取类型
收费全文 | 1686篇 |
免费 | 33篇 |
国内免费 | 11篇 |
专业分类
化学 | 1133篇 |
晶体学 | 16篇 |
力学 | 63篇 |
数学 | 92篇 |
物理学 | 426篇 |
出版年
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 16篇 |
2019年 | 18篇 |
2018年 | 12篇 |
2017年 | 15篇 |
2016年 | 35篇 |
2015年 | 25篇 |
2014年 | 32篇 |
2013年 | 95篇 |
2012年 | 92篇 |
2011年 | 93篇 |
2010年 | 55篇 |
2009年 | 59篇 |
2008年 | 100篇 |
2007年 | 86篇 |
2006年 | 86篇 |
2005年 | 76篇 |
2004年 | 79篇 |
2003年 | 78篇 |
2002年 | 65篇 |
2001年 | 35篇 |
2000年 | 35篇 |
1999年 | 26篇 |
1998年 | 17篇 |
1997年 | 19篇 |
1996年 | 19篇 |
1995年 | 19篇 |
1994年 | 28篇 |
1993年 | 30篇 |
1992年 | 26篇 |
1991年 | 24篇 |
1990年 | 21篇 |
1989年 | 18篇 |
1988年 | 24篇 |
1987年 | 18篇 |
1986年 | 11篇 |
1985年 | 25篇 |
1984年 | 35篇 |
1983年 | 14篇 |
1982年 | 17篇 |
1981年 | 17篇 |
1980年 | 16篇 |
1979年 | 8篇 |
1978年 | 16篇 |
1977年 | 13篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有1730条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Protein profiling of rat cerebella during development 总被引:7,自引:0,他引:7
Protein profiles of developing rat cerebella were analyzed by means of two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS). The analysis of adult rat cerebellum gave rise to a protein map comprising approximately 3000 spots detectable by silver staining following high resolution 2-DE with a pH range of 3-10 and a mass range of 8-100 kDa. To obtain landmarks for comparison of developmental profiles of cerebellar proteins, 100 spots were subjected to peptide mass fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and 67 spots were assigned on the map. Analysis of profiles of the developing cerebella revealed significant changes in the expression of proteins during development. In most cases the expression levels of proteins increased as the cerebellum matured, while the expression of 42 spots appeared specific or remarkably abundant in the immature cerebellum. Peptide mass fingerprinting of these spots allowed us to identify 29 proteins, which include, in addition to proteins of unknown function, many proteins known to have roles in the development of the central nervous system. These results suggest that the proteomic approach is valuable for mass identification of proteins involved in cerebellar morphogenesis. 相似文献
5.
The steric hindrance between the oxygen and halogen atoms results in the structural deformation of α-haloanthraquinones and their lowest excited triplet (T1) states are of mixed nπ *-ππ * or ππ * character with unusually short lifetimes. Moreover, the rates of hydrogen-atom abstraction from ethanol by the T1 states decrease with their increasing ππ * character, and the proximity of the halogen atom to the hydroxy group causes the photochemical intramolecular elimination of hydrogen halide from the initial photoproducts (α-haloanthrahydroquinones) yielding α-haloanthraquinones (or anthraquinone) with one less halogen atom than the original molecule; the final product is anthrahydroquinone. The remarkably large structural deformation of 1,8-dihaloanthrasemiquinone radicals which gives rise to the simultaneous formation of 1,8-dihaloanthrahydroquinones and the original anthraquinones. Of particular interest is observation of the absorption band(s) attributable to the second excited triplet (T2) states of 1,8-dihaloanthraquinones. However, the electron transfer from triethylamine (TEA) to these T2 states generating the radical anions is observed only in acetonitrile, while that to the T1 states generating their exciplexes with TEA is observed not only in acetonitrile but also in toluene and ethanol. 相似文献
6.
The properties of some chelate-forming resins prepared from common anion-exchange resins by treatment with reagents bearing chelate-forming and ion-exchange groups have been studied. A resin prepared from the sulphonic acid derivative of dithizone (DzS) was found to be superior to other chelate-forming resins. Resins loaded with DzS, tetraphenylporphinetrisulphonic acid or zincon were stable in 1M sodium chloride. Resins prepared from sulphonazo III, arsenazo III, thiosalicylic acid or p-mercaptobenzenesulphonic acid were found to be unstable when exposed to sodium chloride solution. 相似文献
7.
Novel 1,4-elimination reaction of C,N-bis(trimethylsilyl)-C- trimethylsiloxymethylketenimine and retro Diels-Alder reaction of 2-oligosiloxanyl-5-norbornene-2-carbonitrile cleanly gave α-oligosiloxanylacrylonitriles in excellent yield. 相似文献
8.
A series of thiiranes react with benzyne to provide an efficient synthesis of phenyl vinyl sulfides. The reaction is stereospecific, thus producing cis-(phenylthio)-stilbene from cis-2,3-diphenylthiirane and trans-(phenylthio)stilbene from trans-2,3-diphenylthiirane. 相似文献
9.
10.
An integral treatment was proposed for analysis of non-Darcy free convection over a vertical flat plate and cone within a fluid-saturated porous medium. A flexible one-parameter family of third order polynomials was employed to cope with vast changes in the velocity and temperature profiles encountered in the Darcy flow limit through to the Forchheimer flow limit. Zero curvature requirement for the temperature profile at the wall was exploited as an auxiliary relation to determine the shape parameter. Comparison of the approximate results with the exact solution reveals a high performance of the present integral procedure for heat transfer rat prediction. 相似文献