全文获取类型
收费全文 | 789篇 |
免费 | 78篇 |
国内免费 | 60篇 |
专业分类
化学 | 502篇 |
力学 | 41篇 |
综合类 | 87篇 |
数学 | 145篇 |
物理学 | 152篇 |
出版年
2023年 | 2篇 |
2022年 | 32篇 |
2021年 | 35篇 |
2020年 | 33篇 |
2019年 | 24篇 |
2018年 | 13篇 |
2017年 | 27篇 |
2016年 | 30篇 |
2015年 | 24篇 |
2014年 | 27篇 |
2013年 | 52篇 |
2012年 | 40篇 |
2011年 | 36篇 |
2010年 | 30篇 |
2009年 | 63篇 |
2008年 | 43篇 |
2007年 | 51篇 |
2006年 | 50篇 |
2005年 | 37篇 |
2004年 | 41篇 |
2003年 | 37篇 |
2002年 | 23篇 |
2001年 | 26篇 |
2000年 | 19篇 |
1999年 | 22篇 |
1998年 | 14篇 |
1997年 | 17篇 |
1996年 | 11篇 |
1995年 | 8篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有927条查询结果,搜索用时 593 毫秒
51.
A rat brain protein expression map including cytosolic and enriched mitochondrial and microsomal fractions 总被引:9,自引:0,他引:9
Proteomics is a powerful tool to screen brain protein expression but the methodology is hampered by low abundance of proteins or compartmentalization or overload of high-abundance proteins. It was therefore the aim of the study to determine the expression of brain proteins by using enriched cellular subfractions and pre-electrophoretic chromatographical separation of brain homogenates. We used two-dimensional electrophoresis with subsequent matrix-assisted laser desorption/ionization (MALDI) detection and characterization of brain proteins. Subfractionation into cytosolic, mitochondrial and microsomal compartments was performed by ultracentrifugation. Pre-electrophoretic fractionation of the cytosolic fractions was carried out by ion exchange column chromatography. We detected and identified a large series of 437 proteins in rat brain and have shown proteins specific for the individual subcellular compartments. These proteins included housekeeping, signaling, cytoskeletal, intermediary metabolism, antioxidant proteins on the one and neuron and synaptosomal specific proteins on the other hand. Using fractionations of brain homogenates we were able to improve the power of the method on forming the basis for brain protein expressional studies and providing a reference map as a powerful tool for the neuroscientist. 相似文献
52.
53.
54.
55.
A phenomenological approach was used to characterize the cure processes of epoxy resins (a diglycidyl ether of bisphenol A and its modifier CTBN) from dynamic experiments by DSC. Various kinetic parameters were obtained by using a modified Avrami expression. The resulting overall activation energies for the two systems agreed very well with the published data in the whole cure temperature range. In contrast with the isothermal results and the general dynamic models, a change in the exponent and the non-linear temperature dependence of the rate constant were also observed.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
56.
By introducing a bivariate matrix-valued linear functional on the scalar polynomial space, a general two-dimensional (2-D) matrix Padé-type approximant (BMPTA) in the inner product space is defined in this paper. The coefficients of its denominator polynomials are determined by taking the direct inner product of matrices. The remainder formula is developed and an algorithm for the numerator polynomials is presented when the generating polynomials are given in advance. By means of the Hankel-like coefficient matrix, a determinantal expression of BMPTA is presented. Moreover, to avoid the computation of the determinants, two efficient recursive algorithms are proposed. At the end the method of BMPTA is applied to partial realization problems of 2-D linear systems. 相似文献
57.
建立了对称常微分算子von N eum ann自伴延拓与以边条件形式表达的自伴延拓之间的对应关系,给出了相互转换的方法. 相似文献
58.
59.
60.
本文导出了损伤材料的全量理论,导出了全量公式中H的渐近表达式;最后得到损伤材料平面应变条件下的裂纹尖端的应力应变场。 相似文献