全文获取类型
收费全文 | 48498篇 |
免费 | 6815篇 |
国内免费 | 5821篇 |
专业分类
化学 | 16952篇 |
晶体学 | 273篇 |
力学 | 3893篇 |
综合类 | 864篇 |
数学 | 18854篇 |
物理学 | 20298篇 |
出版年
2024年 | 107篇 |
2023年 | 471篇 |
2022年 | 1128篇 |
2021年 | 1228篇 |
2020年 | 1411篇 |
2019年 | 1252篇 |
2018年 | 1262篇 |
2017年 | 1538篇 |
2016年 | 1803篇 |
2015年 | 1550篇 |
2014年 | 2544篇 |
2013年 | 3525篇 |
2012年 | 2683篇 |
2011年 | 3075篇 |
2010年 | 2709篇 |
2009年 | 3274篇 |
2008年 | 3287篇 |
2007年 | 3423篇 |
2006年 | 3120篇 |
2005年 | 2778篇 |
2004年 | 2386篇 |
2003年 | 2202篇 |
2002年 | 1878篇 |
2001年 | 1590篇 |
2000年 | 1562篇 |
1999年 | 1359篇 |
1998年 | 1239篇 |
1997年 | 1041篇 |
1996年 | 821篇 |
1995年 | 699篇 |
1994年 | 620篇 |
1993年 | 451篇 |
1992年 | 398篇 |
1991年 | 344篇 |
1990年 | 297篇 |
1989年 | 247篇 |
1988年 | 226篇 |
1987年 | 200篇 |
1986年 | 168篇 |
1985年 | 199篇 |
1984年 | 149篇 |
1983年 | 95篇 |
1982年 | 139篇 |
1981年 | 117篇 |
1980年 | 86篇 |
1979年 | 86篇 |
1978年 | 77篇 |
1977年 | 64篇 |
1976年 | 65篇 |
1973年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Differentiation of functions w.r.t. finite atomless measures with compact support on the real line is introduced. The related harmonic calculus is similar to that of the classical Lebesgue case. As an application we obtain the Weyl exponent for the spectral asymptotics of the Laplacians w.r.t. linear Cantor-type measures with arbitrary weights. 相似文献
92.
Robert J. Rubin 《Journal of statistical physics》1991,65(5-6):1207-1216
A one-dimensional lattice random walk in the presence ofm equally spaced traps is considered. The step length distribution is a symmetric exponential. An explicit analytic expression is obtained for the probability that the random walk will be trapped at thejth trapping site. 相似文献
93.
94.
In this paper, the deconvolution of SIMS profiles analysed at very low primary energy (0.5 keV/O2+) is addressed. The depth resolution function (DRF) of the SIMS analysis in presence of roughness is established and a deconvolution procedure is implemented without or in presence of roughness on samples containing delta-doped layers of boron in silicon. It is shown that the deconvolution procedure can lead to a great improvement of the full width at half maximum (FWHM) of the measured peaks in the case where no roughness in detected in the crater bottom. In the case where it is present, the conditions required to use a deconvolution procedure are discussed, and the deconvolution is implemented using precise and restrictive assumptions. 相似文献
95.
Differential inequality method, bounding function method and topological degree are applied to obtain the existence criterions of at least one solution for the general fourth-order differential equations under nonlinear boundary conditions, and many existing results are complemented. 相似文献
96.
The decay process J/ψ→p X X→p P,where p,p and P are the proton,antiproton and pseudoscalar states,respectively,has been studied in terms of the angular distribution and the generalized moment analysis methods.The result shows that we can identify the spin,but cannot determine the parity of the baryon resonance state X produced in the process J/ψ→p X X→p P. 相似文献
97.
In this paper we discuss thermodynamics parameters of black hole horizon and cosmological horizon in general high-dimensional space-time. We obtain that the entropy of a cosmological horizon can be described by the Cardy-Verlinde formula. However, the entropy of black hole horizon will be expressed in a form of the Cardy-Verlinde formula, if one adopts the methods given by Abbott and Deser to compute the mass of a black hole in general high-dimensional space-time. Through discussion, relation among various thermodynamics parameters of the black hole in general high-dimensional space-time is given. That is, differential formula of the first law of thermodynamics is obtained. Because we discuss the general high-dimensional space-time, our result has universality.
PACS: 04.20.Dw, 97.60.Lf 相似文献
98.
一类广义Bent型S-Box的构造 总被引:1,自引:0,他引:1
王章雄 《数学的实践与认识》2002,32(6):999-1002
S-box是密码理论与实践中十分重要的一种装置 ,它的密码性能由其分量函数所决定 .于是 ,选择适当的分量函数来构造 S-box就成了一个重要的研究课题 .在一定意义上 ,Bent函数是最优良的密码函数 .本文通过函数序列半群和置换群来构造其任何非零线性组合为 Bent函数与线性函数之和的函数组 ,从而可由 Bent函数构造出具有高度非线性度和其他良好性状的 S-box 相似文献
99.
YAN Zhen-Ya 《理论物理通讯》2002,38(10)
Recently, we obtained thirteen families of Jacobian elliptic function solutions of mKdV equation by usingour extended Jacobian elliptic function expansion method. In this note, the mKdV equation is investigated and anotherthree families of new doubly periodic solutions (Jacobian elliptic function solutions) are fbund again by using a newtransformation, which and our extended Jacobian elliptic function expansion method form a new method still called theextended Jacobian elliptic function expansion method. The new method can be more powertul to be applied to othernonlinear differential equations. 相似文献
100.
Adhesion of zein to solid substrates has been studied using surface energy profiles as indices and by adhesion mapping using
atomic force microscopy (AFM). Different plasticizers like glycerol and sorbitol have been used to form mixed films with zein
and properties of these films are studied using surface energy profiles. Comparison of the results from the different mixed
samples with those from the pure zein films showed that force mapping could identify areas rich in protein. The adhesion maps
produced were deconvoluted from sample topography and contrasted with the data obtained from contact angle measurements. A
comparison of the two methods shows that the extent of contact angle hysteresis is indicative of both hydrophobicity of the
surface as well as the force of adhesion. Mechanical properties and microstructure of zein films prepared by casting from
solutions and using Langmuir-Blodgett film technique have been investigated. Pure zein seemed brittle and exhibited an essentially
linear relationship between stress and strain. Films with plasticizer were tougher than these films. In general, mixed films
showed better mechanical properties than pure films and had higher ultimate tensile strength and increased per cent elongation.
Further, the mixed films of zein showed a higher force of adhesion compared to the pure films. 相似文献