全文获取类型
收费全文 | 7314篇 |
免费 | 285篇 |
国内免费 | 368篇 |
专业分类
化学 | 1580篇 |
晶体学 | 4篇 |
力学 | 285篇 |
综合类 | 61篇 |
数学 | 4827篇 |
物理学 | 1210篇 |
出版年
2024年 | 6篇 |
2023年 | 74篇 |
2022年 | 116篇 |
2021年 | 168篇 |
2020年 | 122篇 |
2019年 | 157篇 |
2018年 | 125篇 |
2017年 | 201篇 |
2016年 | 209篇 |
2015年 | 148篇 |
2014年 | 304篇 |
2013年 | 622篇 |
2012年 | 365篇 |
2011年 | 385篇 |
2010年 | 364篇 |
2009年 | 504篇 |
2008年 | 497篇 |
2007年 | 503篇 |
2006年 | 365篇 |
2005年 | 278篇 |
2004年 | 286篇 |
2003年 | 215篇 |
2002年 | 206篇 |
2001年 | 147篇 |
2000年 | 134篇 |
1999年 | 138篇 |
1998年 | 151篇 |
1997年 | 117篇 |
1996年 | 140篇 |
1995年 | 105篇 |
1994年 | 124篇 |
1993年 | 84篇 |
1992年 | 86篇 |
1991年 | 59篇 |
1990年 | 45篇 |
1989年 | 36篇 |
1988年 | 31篇 |
1987年 | 27篇 |
1986年 | 38篇 |
1985年 | 47篇 |
1984年 | 45篇 |
1983年 | 18篇 |
1982年 | 45篇 |
1981年 | 21篇 |
1980年 | 27篇 |
1979年 | 30篇 |
1978年 | 19篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1973年 | 5篇 |
排序方式: 共有7967条查询结果,搜索用时 265 毫秒
21.
Lihong Wang 《Annals of the Institute of Statistical Mathematics》2004,56(2):251-264
The purpose of this paper is to investigate the asymptotic properties of the least squares estimates (L
2-estimates) and the least absolute deviation estimates (L
1-estimates) of the parameters of a nonlinear regression model subject to a set of equality and inequality restrictions, which
has a long-range dependent stationary process as its stochastic errors. Then we will compare the asymptotic relative efficiencies
of the above estimators. 相似文献
22.
An Application of Branch and Cut to Open Pit Mine Scheduling 总被引:5,自引:0,他引:5
The economic viability of the modern day mine is highly dependent upon careful planning and management. Declining trends in average ore grades, increasing mining costs and environmental considerations will ensure that this situation will remain in the foreseeable future. The operation and management of a large open pit mine having a life of several years is an enormous and complex task. Though a number of optimization techniques have been successfully applied to resolve some important problems, the problem of determining an optimal production schedule over the life of the deposit is still very much unresolved. In this paper we will critically examine the techniques that are being used in the mining industry for production scheduling indicating their limitations. In addition, we present a mixed integer linear programming model for the scheduling problems along with a Branch and Cut solution strategy. Computational results for practical sized problems are discussed. 相似文献
23.
The natural modes of a discrete linear system are orthogonal with respect to the mass and stiffness matrices in a generalized sense. However, these modes are usually not orthogonal to each other in the ordinary sense. The purpose of this paper is to document a number of conditions under which the modes are also orthogonal in an ordinary fashion. 相似文献
24.
25.
26.
《Electroanalysis》2004,16(9):748-756
A strategy for constructing a global multivariate calibration model that includes calibration samples measured over time on different days is developed and applied in electroanalysis. Both synthetic and real samples (tap, extracted and river water) are analyzed by differential‐pulse anodic stripping voltammetry, showing the suitability of the global model constructed that provides successful results similar to those of the usual multivariate calibration. In addition the capability of discrimination of this model is evaluated in prediction for the mean of three replicates with estimation of probability of false noncompliance, α, and false compliance, β, being found 3.1, 11.2, 6.7 and 64.7 nM for nominal concentrations of zinc, cadmium, lead and copper of 96.0, 40.4, 37.3 and 328.0 nM respectively when α=β=0.05. It has been proven that the use of the global calibration does not imply a loss of multivariate analytical sensitivity, using this parameter as quality index of the analytical procedure. The viability of using calibration maintenance strategies with electroanalytical techniques is shown, providing a way to save time and experimental effort when these techniques are used in routine analysis. 相似文献
27.
A server needs to compute a broadcast schedule for n pages whose request times are known in advance. Outputting a page satisfies all outstanding requests for the page. The goal is to minimize the average waiting time of a client. In this paper, we show the equivalence of two apparently different relaxations that have been considered for this problem. 相似文献
28.
Robust linear optimization under general norms 总被引:1,自引:0,他引:1
We explicitly characterize the robust counterpart of a linear programming problem with uncertainty set described by an arbitrary norm. Our approach encompasses several approaches from the literature and provides guarantees for constraint violation under probabilistic models that allow arbitrary dependencies in the distribution of the uncertain coefficients. 相似文献
29.
The projective method for solving linear matrix inequalities 总被引:2,自引:0,他引:2
Numerous problems in control and systems theory can be formulated in terms of linear matrix inequalities (LMI). Since solving
an LMI amounts to a convex optimization problem, such formulations are known to be numerically tractable. However, the interest
in LMI-based design techniques has really surged with the introduction of efficient interior-point methods for solving LMIs
with a polynomial-time complexity. This paper describes one particular method called the Projective Method. Simple geometrical
arguments are used to clarify the strategy and convergence mechanism of the Projective algorithm. A complexity analysis is
provided, and applications to two generic LMI problems (feasibility and linear objective minimization) are discussed. 相似文献
30.
Lai Chunhui 《东北数学》1997,(1)
SomePropertiesofQuasi┐keep┐rangeOperatorsandTheirApplicationsLaiChunhui(赖春晖)(DepartmentofMathematics,ZhangzhouTeachersColege,... 相似文献