全文获取类型
收费全文 | 5149篇 |
免费 | 215篇 |
国内免费 | 175篇 |
专业分类
化学 | 772篇 |
晶体学 | 11篇 |
力学 | 362篇 |
综合类 | 20篇 |
数学 | 3294篇 |
物理学 | 1080篇 |
出版年
2024年 | 4篇 |
2023年 | 35篇 |
2022年 | 69篇 |
2021年 | 74篇 |
2020年 | 141篇 |
2019年 | 162篇 |
2018年 | 131篇 |
2017年 | 109篇 |
2016年 | 114篇 |
2015年 | 133篇 |
2014年 | 259篇 |
2013年 | 715篇 |
2012年 | 276篇 |
2011年 | 322篇 |
2010年 | 277篇 |
2009年 | 346篇 |
2008年 | 341篇 |
2007年 | 349篇 |
2006年 | 237篇 |
2005年 | 135篇 |
2004年 | 153篇 |
2003年 | 136篇 |
2002年 | 107篇 |
2001年 | 77篇 |
2000年 | 87篇 |
1999年 | 77篇 |
1998年 | 74篇 |
1997年 | 58篇 |
1996年 | 62篇 |
1995年 | 66篇 |
1994年 | 60篇 |
1993年 | 51篇 |
1992年 | 36篇 |
1991年 | 28篇 |
1990年 | 33篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 22篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 18篇 |
1980年 | 11篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1972年 | 3篇 |
排序方式: 共有5539条查询结果,搜索用时 31 毫秒
41.
J. -M. Douillard H. Malandrini T. Zoungrana F. Clauss S. Partyka 《Journal of Thermal Analysis and Calorimetry》1994,41(6):1205-1210
It is possible to estimate surface tension of high-energy solids combining the immersion microcalorimetry thermodynamics and Van Oss' model. In this study we have applied this method on talc and talc-chlorite samples in order to obtain thermodynamic values which permit to understand surface properties useful in the industrial applications of these solids. Some talcite samples are preferentially used in specific industrial applications because they are less hydrophobic or more lamellar. This method seems to be reliable to classify the solids and predict some properties. 相似文献
42.
We study the large-sample properties of a class of parametric mixture models with covariates for competing risks. The models allow general distributions for the survival times and incorporate the idea of long-term survivors. Asymptotic results are obtained under a commonly assumed independent censoring mechanism and some modest regularity conditions on the survival distributions. The existence, consistency, and asymptotic normality of maximum likelihood estimators for the parameters of the model are rigorously derived under general sufficient conditions. Specific conditions for particular models can be derived from the general conditions for ready check. In addition, a likelihood-ratio statistic is proposed to test various hypotheses of practical interest, and its asymptotic distribution is provided. 相似文献
43.
W. Schindler 《Computational Geometry》1994,4(6):327-343
Stochastic simulations on manifolds usually are traced back to
n via charts. If a group G is acting on a manifold M and if the respective distribution v is invariant under this group action then in many cases of practical interest there exists a more convenient approach which uses equivariant mappings. The concept of equivariant mappings will be discussed intensively at the instance of the Grassman manifold in which case G equals the orthogonal group. Further advantages of this concept will be demonstrated by applying it to a probabilistic problem from the field of combinatorial geometry. 相似文献
44.
45.
Subgame consistency is a fundamental element in the solution of cooperative stochastic differential games. In particular, it ensures that: (i) the extension of the solution policy to a later starting time and to any possible state brought about by the prior optimal behavior of the players would remain optimal; (ii) all players do not have incentive to deviate from the initial plan. In this paper, we develop a mechanism for the derivation of the payoff distribution procedures of subgame consistent solutions in stochastic differential games with transferable payoffs. The payoff distribution procedure of the subgame consistent solution can be identified analytically under different optimality principles. Demonstration of the use of the technique for specific optimality principles is shown with an explicitly solvable game. For the first time, analytically tractable solutions of cooperative stochastic differential games with subgame consistency are derived. 相似文献
46.
This paper is concerned with processes which are max-plus counterparts of
Markov diffusion processes governed by Ito sense stochastic differential
equations. Concepts of max-plus martingale and max-plus stochastic differential
equation are introduced. The max-plus counterparts of backward and forward
PDEs for Markov diffusions turn out to be first-order PDEs of
Hamilton–Jacobi–Bellman type. Max-plus additive integrals and a max-plus
additive dynamic programming principle are considered. This leads to
variational inequalities of Hamilton–Jacobi–Bellman type. 相似文献
47.
El Kebir Boukas Peng Shi Sing Kiong Nguang 《Journal of Mathematical Analysis and Applications》2003,282(1):241-255
This paper studies the problem of stochastic stability and disturbance attenuation for a class of linear continuous-time uncertain systems with Markovian jumping parameters. The uncertainties are assumed to be nonlinear and state, control and external disturbance dependent. A sufficient condition is provided to solve the above problem. An H∞ controller is designed such that the resulting closed-loop system is stochastically stable and has a disturbance attenuation γ for all admissible uncertainties. It is shown that the control law is in terms of the solutions of a set of coupled Riccati inequalities. A numerical example is included to demonstrate the potential of the proposed technique. 相似文献
48.
The purpose of this paper is to present general approaches for bounding some multi-stage stochastic programs from above. The results are based on restricting the solution set, such that the remaining multi-stage stochastic program is easy to solve. An example where the methods can be applied is presented.Supported in part by NATO Collaborative Research Grant No. 0785/87. 相似文献
49.
Rüdiger Schultz Leen Stougie Maarten H. van der Vlerk 《Mathematical Programming》1998,83(1-3):229-252
In this paper we present a framework for solving stochastic programs with complete integer recourse and discretely distributed right-hand side vector, using Gröbner basis methods from computational algebra to solve the numerous second-stage integer programs. Using structural properties of the expected integer recourse function, we prove that under mild conditions an optimal solution is contained in a finite set. Furthermore, we present a basic scheme to enumerate this set and suggest improvements to reduce the number of function evaluations needed. 相似文献
50.
The solvability of a class of forward-backward stochastic differential equations (SDEs for short) over an arbitrarily prescribed time duration is studied. The authors design a stochastic relaxed control problem, with both drift and difftusion all being controlled, so that the solvability problem is converted to a problem of finding the nodal set of the viscosity solution to a certain Hamilton-Jacobi-Bellman equation. This method overcomes the fatal difficulty encountered in the traditional contraction mapping approach to the existence theorem of such SDEs. 相似文献