全文获取类型
收费全文 | 16874篇 |
免费 | 341篇 |
国内免费 | 117篇 |
专业分类
化学 | 9709篇 |
晶体学 | 106篇 |
力学 | 559篇 |
数学 | 2493篇 |
物理学 | 4465篇 |
出版年
2022年 | 112篇 |
2021年 | 136篇 |
2020年 | 195篇 |
2019年 | 145篇 |
2018年 | 148篇 |
2017年 | 120篇 |
2016年 | 275篇 |
2015年 | 275篇 |
2014年 | 311篇 |
2013年 | 634篇 |
2012年 | 715篇 |
2011年 | 905篇 |
2010年 | 489篇 |
2009年 | 444篇 |
2008年 | 756篇 |
2007年 | 836篇 |
2006年 | 848篇 |
2005年 | 849篇 |
2004年 | 677篇 |
2003年 | 553篇 |
2002年 | 531篇 |
2001年 | 443篇 |
2000年 | 397篇 |
1999年 | 251篇 |
1998年 | 222篇 |
1997年 | 225篇 |
1996年 | 276篇 |
1995年 | 244篇 |
1994年 | 228篇 |
1993年 | 278篇 |
1992年 | 260篇 |
1991年 | 239篇 |
1990年 | 184篇 |
1989年 | 193篇 |
1988年 | 216篇 |
1987年 | 199篇 |
1986年 | 152篇 |
1985年 | 211篇 |
1984年 | 206篇 |
1983年 | 155篇 |
1982年 | 188篇 |
1981年 | 173篇 |
1980年 | 166篇 |
1979年 | 163篇 |
1978年 | 177篇 |
1977年 | 134篇 |
1976年 | 146篇 |
1975年 | 111篇 |
1974年 | 125篇 |
1973年 | 108篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
962.
Matias Sevel Rasmussen Tor Justesen Anders Dohn Jesper Larsen 《European Journal of Operational Research》2012
In the Home Care Crew Scheduling Problem a staff of home carers has to be assigned a number of visits to patients’ homes, such that the overall service level is maximised. The problem is a generalisation of the vehicle routing problem with time windows. Required travel time between visits and time windows of the visits must be respected. The challenge when assigning visits to home carers lies in the existence of soft preference constraints and in temporal dependencies between the start times of visits. 相似文献
963.
964.
W. A. Rijpkema E. M. T. Hendrix R. Rossi J. G. A. J. van der Vorst 《Annals of Operations Research》2016,239(2):613-624
To match products of different quality with end market preferences under supply uncertainty, it is crucial to integrate product quality information in logistics decision making. We present a case of this integration in a meat processing company that faces uncertainty in delivered livestock quality. We develop a stochastic programming model that exploits historical product quality delivery data to produce slaughterhouse allocation plans with reduced levels of uncertainty in received livestock quality. The allocation plans generated by this model fulfil demand for multiple quality features at separate slaughterhouses under prescribed service levels while minimizing transportation costs. We test the model on real world problem instances generated from a data set provided by an industrial partner. Results show that historical farmer delivery data can be used to reduce uncertainty in quality of animals to be delivered to slaughterhouses. 相似文献
965.
Anders Björn 《Potential Analysis》2007,27(4):381-387
We characterize regular boundary points for p-harmonic functions using weak barriers. We use this to obtain some consequences on boundary regularity. The results also
hold for -harmonic functions under the usual assumptions on , and for Cheeger p-harmonic functions in metric spaces.
相似文献
966.
Remco van der Hofstad Frank den Hollander Gordon Slade 《Probability Theory and Related Fields》2007,138(3-4):363-389
We consider critical spread-out oriented percolation above 4 + 1 dimensions. Our main result is that the extinction probability
at time n (i.e., the probability for the origin to be connected to the hyperplane at time n but not to the hyperplane at time n + 1) decays like 1/Bn
2 as , where B is a finite positive constant. This in turn implies that the survival probability at time n (i.e., the probability that the origin is connected to the hyperplane at time n) decays like 1/Bn as . The latter has been shown in an earlier paper to have consequences for the geometry of large critical clusters and for the
incipient infinite cluster. The present paper is Part I in a series of two papers. In Part II, we derive a lace expansion
for the survival probability, adapted so as to deal with point-to-plane connections. This lace expansion leads to a nonlinear
recursion relation for the survival probability. In Part I, we use this recursion relation to deduce the asymptotics via induction. 相似文献
967.
We present a semigroup approach to stochastic delay equations of the form
in the space of continuous functions C[-h,0]. We represent the solution as a C[-h,0]-valued process arising from a stochastic
weak*-integral in the bidual C[-h,0]** and show how
this process can be interpreted as a mild solution of an associated stochastic abstract Cauchy problem. We obtain a necessary
and sufficient condition guaranteeing the existence of an invariant measure. 相似文献
968.
We prove sharp, computable error estimates for the propagation of errors in the numerical solution of ordinary differential equations. The new estimates extend previous estimates of the influence of data errors and discretization errors with a new term accounting for the propagation of numerical round-off errors, showing that the accumulated round-off error is inversely proportional to the square root of the step size. As a consequence, the numeric precision eventually sets the limit for the pointwise computability of accurate solutions of any ODE. The theoretical results are supported by numerically computed solutions and error estimates for the Lorenz system and the van der Pol oscillator. 相似文献
969.
970.
Anders Barrlund 《BIT Numerical Mathematics》1991,31(2):358-363
LetA andA+A be Hermitian positive definite matrices. Suppose thatA=LDL
H and (A+A)=(L+L)(D+D)(L+L)H are theLDL
H decompositons ofA andA+A, respectively. In this paper upper bounds on |D|
F
and |L|
F
are presented. Moreover, perturbation bounds are given for theLU decomposition of a complexn ×n matrix. 相似文献