首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   563篇
  免费   18篇
  2021年   11篇
  2019年   10篇
  2018年   7篇
  2017年   16篇
  2016年   10篇
  2015年   16篇
  2014年   13篇
  2013年   136篇
  2011年   7篇
  2009年   4篇
  2008年   8篇
  2007年   6篇
  2006年   8篇
  2005年   11篇
  2004年   4篇
  2003年   4篇
  2002年   7篇
  2001年   6篇
  2000年   6篇
  1999年   7篇
  1998年   10篇
  1997年   10篇
  1996年   8篇
  1995年   10篇
  1994年   12篇
  1993年   11篇
  1992年   12篇
  1991年   12篇
  1990年   4篇
  1989年   10篇
  1988年   18篇
  1987年   10篇
  1986年   16篇
  1985年   11篇
  1984年   6篇
  1983年   7篇
  1982年   4篇
  1981年   11篇
  1980年   6篇
  1979年   12篇
  1978年   7篇
  1977年   7篇
  1975年   12篇
  1974年   7篇
  1973年   6篇
  1972年   7篇
  1971年   5篇
  1970年   6篇
  1969年   6篇
  1966年   4篇
排序方式: 共有581条查询结果,搜索用时 15 毫秒
411.
India and China are the 2 most populous countries of the world; in the 1950s, both countries initiated a centrally planned program for rapid development within vastly differing political systems. China embarked India's policy encouraged only voluntary acceptance of family planning. In both cases, however, government involvement in population forms a part of comprehensive national planning. Both countries rely on a limited resource base and technological sophistication in order to alleviate mass poverty and misery. The political implications of population growth cannot be neatly isolated from those that are generated by social and economic forces of change in a society that is in a transitional stage of modernization and development. Development has not been an unmixed bleesing; population growth is one of its counterproductive outcomes. The development process has begun to draw increasing attention to hitherto neglected correlates of fertility decline, such as a reduction in infant mortality, universal education, improvement in women's status, and women's participation in economic activity outside the home, all of which eventually result in greater demand for family planning services. Both the Indian and Chinese models highlight the importance of taking the people into one's confidence; the response of the common people to official initiatives is critical in securing a reduction in fertility levels. China has adopted a 1 child family policy, yet it is unreasonable to expect that the Indian people would agree to a nationally prescribed family size norm below 2 children. The principal determinant of future population trends in both these countries is the course of their politics. The success of developing countries will be assured if the developed nations support their progress without being worried about their population growth, which is the result of their unavoidable failure to modernize their social and economic structures.  相似文献   
412.
This paper deals with the problem of finding the optimal dynamic operating policy for an M/M/S queue. The system is observed periodically, and at the beginning of each period the system controller selects the number of service units to be kept open during that period. The optimality criterion used is the total discounted cost over a finite horizon.  相似文献   
413.
The bottleneck transportation problem can be stated as follows: A set of supplies and a set of demands are specified such that the total supply is equal to the total demand. There is a transportation time associated between each supply point and each demand point. It is required to find a feasible distribution (of the supplies) which minimizes the maximum transportaton time associated between a supply point and a demand point such that the distribution between the two points is positive. In addition, one may wish to find from among all optimal solutions to the bottleneck transportation problem, a solution which minimizes the total distribution that requires the maximum time Two algorithms are given for solving the above problems. One of them is a primal approach in the sense that improving fcasible solutions are obtained at each iteration. The other is a “threshold” algorithm which is found to be far superior computationally.  相似文献   
414.
This paper considers a two sided resource allocation game in which both players initially have fixed resources which may be distributed over various targets. Their effectiveness depends on the manner of distribution and also on the strategy of the opponent, a natural payoff function for such a situation being used. The complete solution to the game is derived and a numerical example given.  相似文献   
415.
This paper considers the classical nXm flow shop sequencing problem. An improved branch and bound procedure is proposed. Computational experience shows that the proposed procedure is more efficient compared to the existing optimizing procedures.  相似文献   
416.
417.
418.
The mathematical theory necessary to solve combined arms models of military combat is presented here. We show how to apply the theory of positive operators to such models. Most of the results are purely qualitative in character showing that many properties of such systems are independent of the actual numerical values of the coefficients. Finally, we discuss in some detail an example of such a system.  相似文献   
419.
The present analysis deals with very high-dimensional data sets, each one containing close to 900 binary variables. Each data set corresponds to an evaluation of one complex system. These data sets are characterized by large portions of missing data where, moreover, the unobserved variables are not the same in different evaluations. Thus, the problems which confront the statistical analysis are those of multivariate binary data analysis, where the number of variables is much larger than the sample size and in which missing data varies with the sample elements. The variables, however, are hierarchically structured and the problem of clustering variables to groups does not exist in the present study. In order to motivate the statistical problem under consideration, the Marine Corps Combat Readiness Evaluation System (MCCRES) is described for infantry battalions and then used for exposition. The present article provides a statistical model for data from MCCRES and develops estimation and prediction procedures which utilize the dependence structure. The E-M algorithm is applied to obtain maximum-likelihood estimates of the parameters of interest. Numerical examples illustrate the proposed methods.  相似文献   
420.
A new bivariate negative binomial distribution is derived by convoluting an existing bivariate geometric distribution; the probability function has six parameters and admits of positive or negative correlations and linear or nonlinear regressions. Given are the moments to order two and, for special cases, the regression function and a recursive formula for the probabilities. Purely numerical procedures are utilized in obtaining maximum likelihood estimates of the parameters. A data set with a nonlinear empirical regression function and another with negative sample correlation coefficient are discussed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号