全文获取类型
收费全文 | 1112篇 |
免费 | 89篇 |
国内免费 | 41篇 |
专业分类
电工技术 | 38篇 |
综合类 | 192篇 |
化学工业 | 92篇 |
金属工艺 | 13篇 |
机械仪表 | 42篇 |
建筑科学 | 38篇 |
矿业工程 | 15篇 |
能源动力 | 33篇 |
轻工业 | 39篇 |
水利工程 | 15篇 |
石油天然气 | 4篇 |
武器工业 | 11篇 |
无线电 | 108篇 |
一般工业技术 | 92篇 |
冶金工业 | 32篇 |
原子能技术 | 18篇 |
自动化技术 | 460篇 |
出版年
2023年 | 5篇 |
2022年 | 13篇 |
2021年 | 9篇 |
2020年 | 20篇 |
2019年 | 32篇 |
2018年 | 31篇 |
2017年 | 29篇 |
2016年 | 25篇 |
2015年 | 48篇 |
2014年 | 47篇 |
2013年 | 76篇 |
2012年 | 72篇 |
2011年 | 80篇 |
2010年 | 56篇 |
2009年 | 66篇 |
2008年 | 133篇 |
2007年 | 77篇 |
2006年 | 50篇 |
2005年 | 40篇 |
2004年 | 38篇 |
2003年 | 35篇 |
2002年 | 28篇 |
2001年 | 26篇 |
2000年 | 23篇 |
1999年 | 20篇 |
1998年 | 21篇 |
1997年 | 13篇 |
1996年 | 15篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 2篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1242条查询结果,搜索用时 109 毫秒
91.
为了消除传统的纯数字加密技术(PNCT)保密性的缺陷,即泄密性、期限性和死密性,提出了一种新的基于变进数(VCN)智能特性的PNCT。传统的PNCT生成的准密码数均是恒进数(FCN),其变化规则(FCR)的单一性、机械性和难记性,造成其保密性缺陷。VCN则是FCN的拓展,是一种新的更为广义概念上的数,但其变化规则(VCR)的复杂性、智能性和灵活性,可以克服FCN的保密性缺陷。 相似文献
92.
G. Gordon Cameron James L. Harvie Malcolm D. Ingram Graham A. Sorrie 《Polymer International》1988,20(3):199-202
Solutions of alkali metal thiocyanates in liquid copolymers of ethylene oxide and propylene oxide provide a convenient medium for measuring conductivities, viscosities and transport numbers in polymer electrolytes by classical methods. The high value of the anion transport number (typically ca. 0.95) is noteworthy. A model, which emphasises the importance of intramolecular solvation of cations, the effects of ion pairing and redissociation, and the crosslinking action of anions at high salt concentrations, accounts satisfactorily for the properties of these liquid systems. 相似文献
93.
The variation of hardness of rhombohedral single crystals of calcite and sodium nitrate with quenching temperature is studied.
Vickers and Knoop hardness numbers are determined from the indentations produced on freshly-cleaved crystal surfaces for various
loads. The variation of hardness number with quenching temperature can be represented byHT
q
k
=constant where the exponentk is less than unity and its sign determines the nature of material. 相似文献
94.
Vijay S. Tripathi 《Computers & Geosciences》1979,5(2):251-268
Computer-generated random numbers form the basis of most Monte-Carlo simulations and similar work. A FORTRAN program—RANTEST—was written that performs various statistical and empirical tests of randomness on uniform (0, 1) pseudorandom numbers. 相似文献
95.
Carl E. Pierchala 《Computational statistics & data analysis》1985,2(4):317-322
This paper documents and provides code for two new entry points which increase the flexibility of the McGill University Random Number Package. With these additions the user can access internal locations containing the pseudo-random integers that control the random sequences produced by the generator. A detailed example of the use of the new entry points is provided. Finally, some comments about the documentation of random number generators are made. 相似文献
96.
We present an explicit formula for the surface area of the (n,k)-star graph, i.e., the number of nodes at a certain distance from the identity node in the graph, by identifying the unique cycle structures associated with the nodes in the graph, deriving a distance expression in terms of such structures between the identity node of the graph and any other node, and enumerating those cycle structures satisfying the distance restriction.The above surface area derivation process can also be applied to some of the other node symmetric interconnection structures defined on the symmetric group, when the aforementioned distance expression is available. 相似文献
97.
We study four problems from the geometry of numbers, the shortest vector problem (Svp), the closest vector problem (Cvp), the successive minima problem (Smp), and the shortest independent vectors problem (Sivp). Extending and generalizing results of Ajtai, Kumar, and Sivakumar we present probabilistic single exponential time algorithms for all four problems for all ?p norms. The results on Smp and Sivp are new for all norms. The results on Svp and Cvp generalize previous results of Ajtai et al. for the Euclidean ?2 norm to arbitrary ?p norms. We achieve our results by introducing a new lattice problem, the generalized shortest vector problem (GSvp). 1 We describe a single exponential time algorithm for GSvp. We also describe polynomial time reductions from Svp,Cvp,Smp, and Sivp to GSvp, establishing single exponential time algorithms for the four classical lattice problems. This approach leads to a unified algorithmic treatment of the lattice problems Svp,Cvp,Smp, and Sivp. 相似文献
98.
Tommaso Bolognesi 《Information Processing Letters》2009,109(13):668-674
Based on the mobile automaton model, an algorithm is introduced that grows planar, tri-valent graphs by exhibiting a peculiar, twofold dynamics. In a first phase, graph growth appears to be pseudo-random and O(n) then it settles to a very regular behavior and rate. A pseudo-random mobile automaton is already known; the new automaton provides now a finite, but surprisingly long, pseudo-random, linear growth process. Applications of mobile automata to fundamental physics and quantum gravity have been recently suggested. 相似文献
99.
100.
区间数互补判断矩阵排序的一种新方法 总被引:7,自引:0,他引:7
研究了决策信息以区间数互补判断矩阵形式给出的多目标决策问题.给出了区间数一致性互补判断矩阵的概念及其判定定理;建立了一个目标规划模型,通过求解该模型得到区间数互补判断矩阵的权重向量;利用已有的可能度公式对方案进行排序与择优.提出了区间数互补判断矩阵排序的目标规划法,该方法具有操作简便和易于上机实现的特点. 相似文献