全文获取类型
收费全文 | 11093篇 |
免费 | 1013篇 |
国内免费 | 744篇 |
专业分类
化学 | 1603篇 |
晶体学 | 30篇 |
力学 | 923篇 |
综合类 | 133篇 |
数学 | 8318篇 |
物理学 | 1843篇 |
出版年
2024年 | 23篇 |
2023年 | 101篇 |
2022年 | 140篇 |
2021年 | 184篇 |
2020年 | 300篇 |
2019年 | 311篇 |
2018年 | 282篇 |
2017年 | 296篇 |
2016年 | 355篇 |
2015年 | 275篇 |
2014年 | 505篇 |
2013年 | 1009篇 |
2012年 | 544篇 |
2011年 | 594篇 |
2010年 | 512篇 |
2009年 | 675篇 |
2008年 | 643篇 |
2007年 | 717篇 |
2006年 | 630篇 |
2005年 | 540篇 |
2004年 | 500篇 |
2003年 | 468篇 |
2002年 | 455篇 |
2001年 | 358篇 |
2000年 | 372篇 |
1999年 | 342篇 |
1998年 | 274篇 |
1997年 | 278篇 |
1996年 | 177篇 |
1995年 | 127篇 |
1994年 | 118篇 |
1993年 | 66篇 |
1992年 | 93篇 |
1991年 | 50篇 |
1990年 | 51篇 |
1989年 | 39篇 |
1988年 | 29篇 |
1987年 | 27篇 |
1986年 | 32篇 |
1985年 | 47篇 |
1984年 | 54篇 |
1983年 | 25篇 |
1982年 | 40篇 |
1981年 | 39篇 |
1980年 | 38篇 |
1979年 | 36篇 |
1978年 | 18篇 |
1977年 | 24篇 |
1976年 | 23篇 |
1974年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
A. E. Mironov 《Functional Analysis and Its Applications》2005,39(3):240-243
We construct commuting rank 2 formally self-adjoint ordinary differential operators corresponding to a curve of genus 2. 相似文献
32.
In this paper we give necessary and sufficient conditions for the existence of a C>
0-semigroup in L
1(I) (I real interval) generated by a second-order differential operator when suitable boundary conditions at the endpoints are imposed. 相似文献
33.
We extend the previously found accelerated Kerr-Schild metrics for Einstein-Maxwell-null dust and Einstein-Born-Infeld-null dust equations to the cases including the cosmological constant. This way we obtain the generalization of the charged de Sitter metrics in static space-times. We also give a generalization of the zero acceleration limit of our previous Einstein-Maxwell and Einstein-Born-Infeld solutions. 相似文献
34.
In this paper, by using elementary analysis, we establish some new Lyapunov-type inequalities for nonlinear systems of differential equations, special cases of which contain the well-known equations such as Emden-Fowler-type and half-linear equations. The inequalities obtained here can be used as handy tools in the study of qualitative behaviour of solutions of the associated equations. 相似文献
35.
Mohamed El-Gebeily Donal O'Regan 《Journal of Mathematical Analysis and Applications》2007,334(1):140-156
Existence theory is developed for the equation ?(u)=F(u), where ? is a formally self-adjoint singular second-order differential expression and F is nonlinear. The problem is treated in a Hilbert space and we do not require the operators induced by ? to have completely continuous resolvents. Nonlinear boundary conditions are allowed. Also, F is assumed to be weakly continuous and monotone at one point. Boundary behavior of functions associated with the domains of definitions of the operators associated with ? in the singular case is investigated. A special class of self-adjoint operators associated with ? is obtained. 相似文献
36.
Wuqing Ning 《Journal of Mathematical Analysis and Applications》2007,327(2):1396-1419
In this paper, an algorithm is established to reconstruct an eigenvalue problem from the given data satisfying certain conditions. These conditions are proved to be not only necessary but also sufficient for the given data to coincide with the spectral characteristics corresponding to the reconstructed eigenvalue problem. 相似文献
37.
In this work, the melting behaviors of nonisothermally and isothermally melt‐crystallized poly(L ‐lactic acid) (PLLA) from the melt were investigated with differential scanning calorimetry (DSC) and temperature‐modulated differential scanning calorimetry (TMDSC). The isothermal melt crystallizations of PLLA at a temperature in the range of 100–110 °C for 120 min or at 110 °C for a time in the range of 10–180 min appeared to exhibit double melting peaks in the DSC heating curves of 10 °C/min. TMDSC analysis revealed that the melting–recrystallization mechanism dominated the formation of the double melting peaks in PLLA samples following melt crystallizations at 110 °C for a shorter time (≤30 min) or at a lower temperature (100, 103, or 105 °C) for 120 min, whereas the double lamellar thickness model dominated the formation of the double melting peaks in those PLLA samples crystallized at a higher temperature (108 or 110 °C) for 120 min or at 110 °C for a longer time (≥45 min). © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 466–474, 2007 相似文献
38.
吴臻 《数学物理学报(B辑英文版)》2004,24(1):91-99
The existence and uniqueness results of fully coupled forward-backward stochastic differential equations with stopping time (unbounded) is obtained. One kind of comparison theorem for this kind of equations is also proved. 相似文献
39.
N. E. Tovmasyan H. A. Babayan 《Journal of Contemporary Mathematical Analysis (Armenian Academy of Sciences)》2007,42(4):198-204
The paper establishes some solvability conditions of the Cauchy problem for linear differential equation in the class of monotone increasing functions. The results are applied for clarifying the possibility of flight along a given trajectory under existence of braking forces. 相似文献
40.
Let P(z) be a polynomial of degree n with complex coefficients and consider the n–th order linear differential operator P(D). We show that the equation P(D)f = 0 has the Hyers–Ulam stability, if and only if the equation P(z) = 0 has no pure imaginary solution. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献