全文获取类型
收费全文 | 18828篇 |
免费 | 795篇 |
国内免费 | 1023篇 |
专业分类
化学 | 5441篇 |
晶体学 | 315篇 |
力学 | 286篇 |
综合类 | 79篇 |
数学 | 9445篇 |
物理学 | 2200篇 |
无线电 | 2880篇 |
出版年
2023年 | 140篇 |
2022年 | 264篇 |
2021年 | 247篇 |
2020年 | 222篇 |
2019年 | 439篇 |
2018年 | 429篇 |
2017年 | 341篇 |
2016年 | 315篇 |
2015年 | 371篇 |
2014年 | 673篇 |
2013年 | 1286篇 |
2012年 | 825篇 |
2011年 | 1276篇 |
2010年 | 1121篇 |
2009年 | 1359篇 |
2008年 | 1356篇 |
2007年 | 1208篇 |
2006年 | 1097篇 |
2005年 | 865篇 |
2004年 | 775篇 |
2003年 | 652篇 |
2002年 | 734篇 |
2001年 | 437篇 |
2000年 | 396篇 |
1999年 | 413篇 |
1998年 | 370篇 |
1997年 | 299篇 |
1996年 | 374篇 |
1995年 | 325篇 |
1994年 | 298篇 |
1993年 | 258篇 |
1992年 | 194篇 |
1991年 | 85篇 |
1990年 | 61篇 |
1989年 | 49篇 |
1988年 | 50篇 |
1987年 | 43篇 |
1985年 | 101篇 |
1984年 | 89篇 |
1983年 | 79篇 |
1982年 | 80篇 |
1981年 | 112篇 |
1980年 | 76篇 |
1979年 | 57篇 |
1978年 | 71篇 |
1977年 | 66篇 |
1976年 | 53篇 |
1975年 | 41篇 |
1974年 | 39篇 |
1973年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
Two groups of 10 speech-language pathology graduate students were each given 7 weeks of singing lessons to determine whether voice lessons could have an effect on their clinical and perceptual skills. Pre-, mid-, and posttests to measure various skills were designed and implemented. With use of paired sample statistical testing, statistically significant results were obtained. In addition, the subjective responses of the students show that the lessons were effective in improving pitch perception, breath control, and legato production or easy onset. This study supports efforts to integrate curricula in vocal performance and speech-language pathology. 相似文献
42.
Summary. We study a diffusion model of an interacting particles system with general drift and diffusion coefficients, and electrostatic
inter-particles repulsion. More precisely, the finite particle system is shown to be well defined thanks to recent results
on multivalued stochastic differential equations (see [2]), and then we consider the behaviour of this system when the number
of particles goes to infinity (through the empirical measure process). In the particular case of affine drift and constant diffusion coefficient,
we prove that a limiting measure-valued process exists and is the unique solution of a deterministic PDE. Our treatment of
the convergence problem (as ) is partly similar to that of T. Chan [3] and L.C.G. Rogers - Z. Shi [5], except we consider here a more general case allowing
collisions between particles, which leads to a second-order limiting PDE.
Received: 5 August 1996 / In revised form: 17 October 1996 相似文献
43.
44.
45.
Summary. We present a simple proof, based on modified logarithmic Sobolev inequalities, of Talagrand’s concentration inequality for
the exponential distribution. We actually observe that every measure satisfying a Poincaré inequality shares the same concentration
phenomenon. We also discuss exponential integrability under Poincaré inequalities and its consequence to sharp diameter upper
bounds on spectral gaps.
Received: 10 June 1996 / In revised form: 9 August 1996 相似文献
46.
Kevin Houston 《Inventiones Mathematicae》2002,147(3):471-485
The disentanglement of certain augmentations is shown to be the topological join of a disentanglement and a Milnor fibre.
The kth disentanglement of a finite map is defined and for corank 1 maps from ℂ
n
to ℂ
n
+1 it is shown that they are homotopically equivalent to a wedge of spheres. Applications to the Mond conjecture are given.
Oblatum 24-VII-2000 & 5-VII-2001?Published online: 12 October 2001 相似文献
47.
Several α-ketoalcohols of synthetic value were resolved using lipase as a catalyst. Lipoprotein lipase (LPL) provided the best rate of hydrolysis and kinetic differentiation. One of these optically pure α-ketoalcohol was converted to (5)-ibuprofen in good optical purity. The stereospecific inversion of (R)-alcohol to (S)-alcohol is described. 相似文献
48.
Sans résumé
相似文献
相似文献
49.
Summary We prove convergence and error estimates in Sobolev spaces for the collocation method with tensor product splines for strongly elliptic pseudodifferential equations on the torus. Examples of applications include elliptic partial differential equations with periodic boundary conditions but also the classical boundary integral operators of potential theory on torus-shaped domains in three or more dimensions. For odd-degree splines, we prove convergence of nodal collocation for any strongly elliptic operator. For even-degree splines and midpoint collocation, we find an additional condition for the convergence which is satisfied for the classical boundary integral operators. Our analysis is a generalization to higher dimensions of the corresponding analysis of Arnold and Wendland [4]. 相似文献
50.
The problem of nonparametric stationary distribution function estimation by the observations of an ergodic diffusion process is considered. The local asymptotic minimax lower bound on the risk of all the estimators is found and it is proved that the empirical distribution function is asymptotically efficient in the sense of this bound. 相似文献