全文获取类型
收费全文 | 2289篇 |
免费 | 128篇 |
国内免费 | 195篇 |
专业分类
林业 | 239篇 |
农学 | 242篇 |
基础科学 | 323篇 |
345篇 | |
综合类 | 1010篇 |
农作物 | 38篇 |
水产渔业 | 111篇 |
畜牧兽医 | 185篇 |
园艺 | 23篇 |
植物保护 | 96篇 |
出版年
2024年 | 14篇 |
2023年 | 39篇 |
2022年 | 68篇 |
2021年 | 52篇 |
2020年 | 75篇 |
2019年 | 86篇 |
2018年 | 44篇 |
2017年 | 89篇 |
2016年 | 96篇 |
2015年 | 60篇 |
2014年 | 107篇 |
2013年 | 118篇 |
2012年 | 146篇 |
2011年 | 184篇 |
2010年 | 134篇 |
2009年 | 110篇 |
2008年 | 113篇 |
2007年 | 122篇 |
2006年 | 112篇 |
2005年 | 94篇 |
2004年 | 96篇 |
2003年 | 60篇 |
2002年 | 62篇 |
2001年 | 57篇 |
2000年 | 39篇 |
1999年 | 39篇 |
1998年 | 42篇 |
1997年 | 35篇 |
1996年 | 37篇 |
1995年 | 37篇 |
1994年 | 35篇 |
1993年 | 29篇 |
1992年 | 35篇 |
1991年 | 30篇 |
1990年 | 41篇 |
1989年 | 24篇 |
1988年 | 25篇 |
1987年 | 17篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有2612条查询结果,搜索用时 31 毫秒
31.
WinSock is a group of API,which is used to transmit data and exchange information on Internet,the Socket Application programme impoldered by users may communicate with other Socket Application programes by Internet. Delphi provides Socket components,which sustains the TCP/IP protocol and makes the Internet programming acquiring much more flexibility.This paper probes that how to realize transmission of files in any format under nonblocking mode between clients and servers by means of Socket components of Delphi. 相似文献
32.
Loss reduction is important for distribution networks and it is available to reduce loss by loads equalization. With increasing numbers of vertexes in distribution networks, compounding of loads are rapid increasing. It is hard to achieve the global optimization for load balancing by traditional model of distribution networks. Base on analyzing character of loads equalization for distribution networks, this paper provides a new method which conjugate the optimization principle and the hierarchical model of the distribution networks, can transfer the optimization issues into multi stage decision making problems,and can also achieve the optimization equalization of the distribution networks loads. 相似文献
33.
For certain types of inventory, the ordering cycle and demand may be random variants, which satisfy certain types distribution. The classical EOQ model usually neglects the fact. Based on the constant demand, under the hypothesis that the ordering cycle is a random variant which satisfies exponent distribution, average demand is a linear increasing function, this paper considers the effects of the time-value of capital and inflation on replenishment strategy of inventory system. Loosening the condition of basic economic order quantity model under deterministic state, the total cost function of the model is provided. The optimum order quantity and cycle are obtained. The application range of EOQ model under the constant demand is widened. The theoretical evidence is provided for the inventory system to make management decision. 相似文献
34.
For the inequality constrained nonlinear programming problem, the antnors propose a new lower order penalty function, which combines the classical l1 penalty function and the lower order exact penalty function introduced in thoy some papers, and then illustrate that it has the merits of the two penalty functions. In additional, we propose a solution method for solving the inequality constrained nonlinear programming problem and prove its global convergence. 相似文献
35.
This paper presents a reactive power optimization method which combines thelinear programming model with secure correction. In correction. this mOdel presents a new idea inwhich the feasible control region of con trol variables is resolved by over constrained state varlables. This method is quick and reliable and overcomes oscillation of a general linear programming model. 相似文献
36.
This paper presents the lately released frame work for Client / Server applica-tions software development, stressing on the characteristics of its OOP and Multi-DataBase supports. 相似文献
37.
Zou Jianbo 《保鲜与加工》1992,(4)
In this paper, the concept of basic for linear vector extreme value problem is introduced in the partially ordered vector space. Some properties and results of the linear programming are generalized. And the existaence therom of basic optimal solution is proved. 相似文献
38.
Tang Jian Duan Yurong 《保鲜与加工》1991,(1):33-41
A new trust region algorithm is proposed for solving unconstrained optimization problems. According to the quadratic approximate model of the original optimization problem,the trust region algorithm uses directions,a convex combination of the quasi-newton direction and the steepest descent direction. This algorithm with new strategy is analyzed and the global and local quadratic convergent theorems are proved. At last,the implementation and computational results of the algorithm are demonstrated. 相似文献
39.
In order to support flexibility and reusability of application composition based on Internet,with business rule and Aspect-Oriented Programming(AOP) which divides a business process into a control business process and a core business process,the authorsgive composition mechanism.A technique of implementation is analyzed.At last,the primary application of the above work in Chongqing of China is introduced,as well as some effects acquired. 相似文献
40.
基于AutoCAD2000的二维图形自动编程软件的开发 总被引:2,自引:0,他引:2
介绍了基于AUTOCAD2000、采用Visual LISP作为开发工具的二维图形自动编程系统的开发,并详细介绍了数据结构、实体排序技术及各模块之间数据流的传送.并通过实例讲解了软件的应用。 相似文献