全文获取类型
收费全文 | 22809篇 |
免费 | 2167篇 |
国内免费 | 1822篇 |
学科分类
工业技术 | 26798篇 |
出版年
2024年 | 51篇 |
2023年 | 237篇 |
2022年 | 383篇 |
2021年 | 501篇 |
2020年 | 605篇 |
2019年 | 596篇 |
2018年 | 559篇 |
2017年 | 723篇 |
2016年 | 846篇 |
2015年 | 901篇 |
2014年 | 1633篇 |
2013年 | 1666篇 |
2012年 | 1853篇 |
2011年 | 1729篇 |
2010年 | 1356篇 |
2009年 | 1540篇 |
2008年 | 1558篇 |
2007年 | 1609篇 |
2006年 | 1346篇 |
2005年 | 1200篇 |
2004年 | 930篇 |
2003年 | 855篇 |
2002年 | 643篇 |
2001年 | 611篇 |
2000年 | 505篇 |
1999年 | 400篇 |
1998年 | 323篇 |
1997年 | 247篇 |
1996年 | 190篇 |
1995年 | 189篇 |
1994年 | 158篇 |
1993年 | 137篇 |
1992年 | 104篇 |
1991年 | 82篇 |
1990年 | 83篇 |
1989年 | 93篇 |
1988年 | 66篇 |
1987年 | 34篇 |
1986年 | 26篇 |
1985年 | 28篇 |
1984年 | 18篇 |
1983年 | 20篇 |
1982年 | 16篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1975年 | 9篇 |
1964年 | 8篇 |
1963年 | 10篇 |
1961年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
针对组群通讯环境中的身份认证式密钥交换问题,基于Diffie-Hellman判定性问题的难解性假设构造了一个基于口令的身份认证组群密钥交换协议Pw/GAKE。该协议具有很高的计算效率,所有组群成员仅需参与一轮消息传输和一次广播、仅需进行幂指数运算和散列运算而无需借助任何复杂的公钥密码方案,因此特别适合于无线/移动自组网络环境中的中小规模组群。在随机oracle模型下证明了该协议的安全性。该证明将协议Pw/GAKE的安全性质归结为Abdella-Pointcheval所建立的2-方密钥交换协议SPAKE的安全性质,显示出Pw/GAKE的构造具有很强的递归特征。 相似文献
994.
Olga Vasilieva 《Asian journal of control》2001,3(1):50-56
The present paper is focused on the finite‐time differential game of m players with nonzero sum. The principal difference from regular cases consists in the fact that the states of players are subordinated to boundary value system of ordinary differential equations (rather than the initial value system). By the end of the game we understand the equilibrium situation and our purpose is to design a well‐founded suitable method for the equilibrium control search. 相似文献
995.
The necessary and sufficient conditions for global optimality are derived for an eigenvalue optimization problem. We consider
the generalized eigenvalue problem where real symmetric matrices on both sides are linear functions of design variables. In
this case, a minimization problem with eigenvalue constraints can be formulated as Semi-Definite Programming (SDP). From the
Karush-Kuhn-Tucker conditions of SDP, the necessary and sufficient conditions are derived for arbitrary multiplicity of the
lowest eigenvalues for the case where important lower bound constraints are considered for the design variables.
Received May 18, 2000 相似文献
996.
水利枢纽泄洪闸门的控制 总被引:1,自引:0,他引:1
戴上安 《计算机与数字工程》2001,29(1):1-6
系统的构成和控制方式以及信息处理能力,对于控制系统的可靠性、安全性、稳定性而言,是决定性的因素,本文对泄洪闸门控制系统的主要技术问题进行分析。 相似文献
997.
Binding Virtual Environments to Toolkit Capabilities 总被引:1,自引:0,他引:1
There are many toolkits and development environments that aid the process of constructing virtual environment applications. Many of these development environments encourage customising a virtual environment's design while rapid prototyping within the confines of a toolkit's capabilities. Thus the choice of the technology and its associated support has been made independent of the end-use requirements of the final system. This can bias a virtual environment's design by implementation based constraints. We propose that an alternative approach is the consideration of virtual environment requirements in the context of an inspectable design model, to identify the requirements that a toolkit will need to support. In the context of an example, we present a selection of design requirements that we consider important for virtual environment design in general. We explore how these requirements might be mapped to different capabilities using Virtual Reality Modelling Language (VRML) as a concrete example of a platform technology. 相似文献
998.
Since wavelets were introduced in the radiosity algorithm 5 , surprisingly little research has been devoted to higher order wavelets and their use in radiosity algorithms. A previous study 13 has shown that wavelet radiosity, and especially higher order wavelet radiosity was not bringing significant improvements over hierarchical radiosity and was having a very important extra memory cost, thus prohibiting any effective computation. In this paper, we present a new implementation of wavelets in the radiosity algorithm, that is substantially different from previous implementations in several key areas (refinement oracle, link storage, resolution algorithm). We show that, with this implementation, higher order wavelets are actually bringing an improvement over standard hierarchical radiosity and lower order wavelets. 相似文献
999.
We present a new interpolatory subdivision scheme for triangle meshes. Instead of splitting each edge and performing a 1-to-4 split for every triangle we compute a new vertex for every triangle and retriangulate the old and the new vertices. Using this refinement operator the number of triangles only triples in each step. New vertices are computed with a Butterfly like scheme. In order to obtain overall smooth surfaces special rules are necessary in the neighborhood of extraordinary vertices. The scheme is suitable for adaptive refinement by using an easy forward strategy. No temporary triangles are produced here which allows simpler data structures and makes the scheme easy to implement. 相似文献
1000.
知识获取的粗分析方法 总被引:2,自引:0,他引:2
粗分析方法是从决策表中挖掘规则,克服知识获取瓶颈的一种有效方法。基于粗糙集理论,文章讨论了粗分析获取规则的几个问题,提出了相应的解决方法。如实用中决策表的约简会导致部分信息丢失,而规则适当的冗余可以解决这个问题。其次,研究了不完全决策表的规则粗分析,为不完全决策提供了基础。 相似文献