全文获取类型
收费全文 | 12768篇 |
免费 | 2562篇 |
国内免费 | 5247篇 |
专业分类
化学 | 8232篇 |
晶体学 | 177篇 |
力学 | 1098篇 |
综合类 | 529篇 |
数学 | 5340篇 |
物理学 | 5201篇 |
出版年
2024年 | 79篇 |
2023年 | 399篇 |
2022年 | 415篇 |
2021年 | 439篇 |
2020年 | 376篇 |
2019年 | 359篇 |
2018年 | 264篇 |
2017年 | 423篇 |
2016年 | 457篇 |
2015年 | 545篇 |
2014年 | 1050篇 |
2013年 | 790篇 |
2012年 | 892篇 |
2011年 | 973篇 |
2010年 | 940篇 |
2009年 | 932篇 |
2008年 | 1103篇 |
2007年 | 960篇 |
2006年 | 944篇 |
2005年 | 946篇 |
2004年 | 891篇 |
2003年 | 802篇 |
2002年 | 670篇 |
2001年 | 688篇 |
2000年 | 498篇 |
1999年 | 477篇 |
1998年 | 463篇 |
1997年 | 459篇 |
1996年 | 363篇 |
1995年 | 375篇 |
1994年 | 331篇 |
1993年 | 264篇 |
1992年 | 252篇 |
1991年 | 214篇 |
1990年 | 214篇 |
1989年 | 183篇 |
1988年 | 42篇 |
1987年 | 32篇 |
1986年 | 20篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1963年 | 1篇 |
1959年 | 4篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 515 毫秒
101.
102.
103.
本文用凸函数的方法研究了概率测度的矩母函数和由C.J.Stone提出的拟对称性,并刻画了Martin边界的法向量.拟对称性在随机游动的比例极限定理中是一个重要的概念.这些结果可应用于Levy过程的研究. 相似文献
104.
We investigate the nonlinear correlations of protein sequences by using the nonlinear prediction method developed in nonlinear dynamical theory. It is found that a lot of protein sequences show strong nonlinear correlations and have deterministic structures. Further investigations show that the strong nonlinear correlations of these protein sequences are due to the symmetries of their tertiary structures. Furthermore, the correlation lengths of the sequences are related to the degrees of the symmetries. These results support the duplication mechanism of protein evolution and also reveal one aspect how amino acid sequences encode their spatial structures. 相似文献
105.
G.A.Gamal M.AbouZied A.A.Ebnalwaled 《中国物理快报》2005,22(6):1530-1532
Single crystals of red Tl2S5 were prepared by a special modified vertical Bridgman and Stockbarger technique.This growth was performed in our laboratory. The influences of temperature on the electrical conductivity, Hall mobility, carrier concentration, and thermoelectric power (TEP) were carried out in the temperature range 277-413K. Throughout these measurements, various physical parameters such as effective mass of charge carriers,carrier mobility, diffusion coefficient, and the relaxation time for both majority and minority carriers were found. 相似文献
106.
107.
This paper concentrates on studying the Lie symmetries and conserved quantities of controllable nonholonomic dynamical systems. Based on the infinitesimal transformation, we establish the Lie symmetric determining equations and restrictive equations and give three definitions of Lie symmetries before the structure equations and conserved quantities of the Lie symmetries are obtained. Then we make a study of the inverse problems. Finally, an example is presented for illustrating the results. 相似文献
108.
ZuoWei 《近代物理研究所和兰州重离子加速器实验室年报》2003,(1):6-6
The three-body force effects on the equation of state and its iso-spin dependence of asymmetric nuclear matter and on the proton fraction in neutron star matter have been investigated[1] within Brueckner Hartree-Fock (BHF) approach by using a microscopic three-body force. It is shown that, even in the presence of the three-body force, the empirical parabolic law of the energy per nucleon vs. isospin asymmetry β=(N-Z)/A is fulfilled in the whole asymmetry range 0 ≤β ≤1 and also up to high density. The three-body force provides a strong enhancement of symmetry energy at high density in agreement with relativistic approaches. Thecalculated proton fraction in β stable neutron star matter is given in Fig.l, where the thick solid line is the BHF prediction using AV18 TBF, while the dotted one is the BHF result using AVis. The thin solid line is the prediction of the Dirac-Brueckner approach taken from Ref.[2]. The results extracted according to the phenomenological paramete rizations of the symmetry energy suggested in Ref.[3] are also plotted. It is seen from 相似文献
109.
氘作同位素交换气对除氚后的新鲜氘氚化锂残渣[主要成分是硅锂化合物和二氧化硅,渣中含氚约为0.9443mg/g(渣)]中的微量氚进行氚的计量与回收,为氘氚化锂残渣中氚的回收提供技术支持。 相似文献
110.
用A的不变子空间作参数,给出了算子方程AX=XAX的全部解。当A是单射或稠值域时,或者当A是正规算子时,给出了算子方程AX=XA=XAX的全部解。我们还给出正规算子X是算子方程AX=XZ=XAX的解的充分必要条件。 相似文献