全文获取类型
收费全文 | 3336篇 |
免费 | 83篇 |
国内免费 | 1篇 |
专业分类
3420篇 |
出版年
2021年 | 37篇 |
2019年 | 89篇 |
2018年 | 51篇 |
2017年 | 81篇 |
2016年 | 78篇 |
2015年 | 61篇 |
2014年 | 65篇 |
2013年 | 699篇 |
2010年 | 35篇 |
2009年 | 39篇 |
2008年 | 50篇 |
2007年 | 52篇 |
2006年 | 36篇 |
2005年 | 43篇 |
2004年 | 58篇 |
2003年 | 42篇 |
2002年 | 57篇 |
1999年 | 41篇 |
1998年 | 46篇 |
1997年 | 47篇 |
1996年 | 61篇 |
1995年 | 41篇 |
1994年 | 59篇 |
1993年 | 63篇 |
1992年 | 58篇 |
1991年 | 74篇 |
1990年 | 39篇 |
1989年 | 72篇 |
1988年 | 79篇 |
1987年 | 68篇 |
1986年 | 72篇 |
1985年 | 66篇 |
1984年 | 36篇 |
1983年 | 42篇 |
1982年 | 43篇 |
1981年 | 46篇 |
1980年 | 51篇 |
1979年 | 45篇 |
1978年 | 49篇 |
1977年 | 45篇 |
1976年 | 45篇 |
1975年 | 46篇 |
1974年 | 52篇 |
1973年 | 50篇 |
1972年 | 52篇 |
1971年 | 43篇 |
1970年 | 40篇 |
1969年 | 40篇 |
1968年 | 34篇 |
1967年 | 34篇 |
排序方式: 共有3420条查询结果,搜索用时 0 毫秒
941.
Mary W. Cooper 《海军后勤学研究》1980,27(1):89-95
This paper presents an application of a method for finding the global solution to a problem in integers with a separable objective function of a very general form. This report shows that there is a relationship between an integer problem with a separable nonlinear objective function and many constraints and a series of nonlinear problems with only a single constraint, each of which can be solved sequentially using dynamic programming. The first solution to any of the individual smaller problems that satisfies the original constraints in addition, will be the optimal solution to the multiply-constrained problem. 相似文献
942.
This note consists of developing a method for enforcing additional constraints to linear fractional programs and showing its usefulness in solving integer linear fractional programs. 相似文献
943.
A. R. Washburn 《海军后勤学研究》1980,27(2):315-322
We consider the problem of searching for a target that moves in discrete time and space according to some Markovian process. At each time, a searcher attempts to detect the target. If the searcher's action at each time is such as to maximize his chances of immediate detection, we call his strategy “myopic.” We provide a computationally useful necessary condition for optimality, and use it to provide an example wherein the myopic strategy is not optimal. 相似文献
944.
The problem of computing reliability and availability and their associated confidence limits for multi-component systems has appeared often in the literature. This problem arises where some or all of the component reliabilities and availabilities are statistical estimates (random variables) from test and other data. The problem of computing confidence limits has generally been considered difficult and treated only on a case-by-case basis. This paper deals with Bayes confidence limits on reliability and availability for a more general class of systems than previously considered including, as special cases, series-parallel and standby systems applications. The posterior distributions obtained are exact in theory and their numerical evaluation is limited only by computing resources, data representation and round-off in calculations. This paper collects and generalizes previous results of the authors and others. The methods presented in this paper apply both to reliability and availability analysis. The conceptual development requires only that system reliability or availability be probabilities defined in terms acceptable for a particular application. The emphasis is on Bayes Analysis and the determination of the posterior distribution functions. Having these, the calculation of point estimates and confidence limits is routine. This paper includes several examples of estimating system reliability and confidence limits based on observed component test data. Also included is an example of the numerical procedure for computing Bayes confidence limits for the reliability of a system consisting of N failure independent components connected in series. Both an exact and a new approximate numerical procedure for computing point and interval estimates of reliability are presented. A comparison is made of the results obtained from the two procedures. It is shown that the approximation is entirely sufficient for most reliability engineering analysis. 相似文献
945.
A single component system is assumed to progress through a finite number of increasingly bad levels of deterioration. The system with level i (0 ≤ i ≤ n) starts in state 0 when new, and is definitely replaced upon reaching the worthless state n. It is assumed that the transition times are directly monitored and the admissible class of strategies allows substitution of a new component only at such transition times. The durations in various deterioration levels are dependent random variables with exponential marginal distributions and a particularly convenient joint distribution. Strategies are chosen to maximize the average rewards per unit time. For some reward functions (with the reward rate depending on the state and the duration in this state) the knowledge of previous state duration provides useful information about the rate of deterioration. 相似文献
946.
This work is concerned with a particular class of bimatrix games, the set of equilibrium points of which games possess many of the properties of solutions to zero-sum games, including susceptibility to solution by linear programming. Results in a more general setting are also included. Some of the results are believed to constitute interesting potential additions to elementary courses in game theory. 相似文献
947.
This paper gives characterization of optimal Solutions for convex semiinfinite programming problems. These characterizations are free of a constraint qualification assumption. Thus they overcome the deficiencies of the semiinfinite versions of the Fritz John and the Kuhn-Tucker theories, which give only necessary or sufficient conditions for optimality, but not both. 相似文献
948.
A general class of continuous time nonlinear problems is considered. Necessary and sufficient conditions for the existence of solutions are established and optimal solutions are characterized in terms of a duality theorem. The theory is illustrated by means of an example. 相似文献
949.
This paper considers the classical finite linear transportation Problem (I) and two relaxations, (II) and (III), of it based on papers by Kantorovich and Rubinstein, and Kretschmer. Pseudo-metric type conditions on the cost matrix are given under which Problems (I) and (II) have common optimal value, and a proper subset of these conditions is sufficient for Problems (II) and (III) to have common optimal value. The relationships between the three problems provide a proof of Kantorovich's original characterization of optimal solutions to the standard transportation problem having as many origins as destinations. The result are extended to problems having cost matrices which are nonnegative row-column equivalent. 相似文献
950.
Let , where A (t)/t is nondecreasing in t, {P(k)1/k} is nonincreasing. It is known that H(t) = 1 — H (t) is an increasing failure rate on the average (IFRA) distribution. A proof based on the IFRA closure theorem is given. H(t) is the distribution of life for systems undergoing shocks occurring according to a Poisson process where P (k) is the probability that the system survives k shocks. The proof given herein shows there is an underlying connection between such models and monotone systems of independent components that explains the IFRA life distribution occurring in both models. 相似文献