全文获取类型
收费全文 | 488874篇 |
免费 | 2827篇 |
国内免费 | 1261篇 |
专业分类
电工技术 | 8362篇 |
综合类 | 2711篇 |
化学工业 | 70871篇 |
金属工艺 | 20997篇 |
机械仪表 | 16432篇 |
建筑科学 | 10488篇 |
矿业工程 | 2698篇 |
能源动力 | 12755篇 |
轻工业 | 32278篇 |
水利工程 | 5596篇 |
石油天然气 | 8340篇 |
武器工业 | 17篇 |
无线电 | 58266篇 |
一般工业技术 | 98246篇 |
冶金工业 | 77323篇 |
原子能技术 | 9788篇 |
自动化技术 | 57794篇 |
出版年
2022年 | 2594篇 |
2021年 | 4048篇 |
2020年 | 3265篇 |
2019年 | 4123篇 |
2018年 | 20244篇 |
2017年 | 19188篇 |
2016年 | 16533篇 |
2015年 | 4951篇 |
2014年 | 7363篇 |
2013年 | 20235篇 |
2012年 | 14371篇 |
2011年 | 24222篇 |
2010年 | 19996篇 |
2009年 | 18966篇 |
2008年 | 20572篇 |
2007年 | 21206篇 |
2006年 | 12541篇 |
2005年 | 12254篇 |
2004年 | 11545篇 |
2003年 | 11523篇 |
2002年 | 10408篇 |
2001年 | 9834篇 |
2000年 | 9318篇 |
1999年 | 9594篇 |
1998年 | 24382篇 |
1997年 | 16750篇 |
1996年 | 12847篇 |
1995年 | 9541篇 |
1994年 | 8396篇 |
1993年 | 8401篇 |
1992年 | 6081篇 |
1991年 | 5727篇 |
1990年 | 5696篇 |
1989年 | 5329篇 |
1988年 | 5055篇 |
1987年 | 4429篇 |
1986年 | 4302篇 |
1985年 | 4815篇 |
1984年 | 4426篇 |
1983年 | 4004篇 |
1982年 | 3663篇 |
1981年 | 3732篇 |
1980年 | 3440篇 |
1979年 | 3329篇 |
1978年 | 3337篇 |
1977年 | 3752篇 |
1976年 | 4847篇 |
1975年 | 2851篇 |
1974年 | 2663篇 |
1973年 | 2730篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Since the topological entropy of a vast class of two-dimensional cellular automata (CA) is infinite, of interest is the possibility to renormalize it so that to obtain a positive finite value. We find the asymptotics of the information function of a multidimensional CA and, accordingly, introduce the renormalized topological entropy as a coefficient of this asymptotics. We describe some properties of the introduced quantity, in particular, its positivity for CA of the type of “The Game of Life.” Also, we give an example of an explicit evaluation of this parameter for a particular cellular automaton. 相似文献
82.
Power distribution systems have been significantly affected by many outage-causing events. Good fault cause identification can help expedite the restoration procedure and improve the system reliability. However, the data imbalance issue in many real-world data sets often degrades the fault cause identification performance. In this paper, the E-algorithm, which is extended from the fuzzy classification algorithm by Ishibuchi to alleviate the effect of imbalanced data constitution, is applied to Duke Energy outage data for distribution fault cause identification. Three major outage causes (tree, animal, and lightning) are used as prototypes. The performance of E-algorithm on real-world imbalanced data is compared with artificial neural network. The results show that the E-algorithm can greatly improve the performance when the data are imbalanced 相似文献
83.
Tomer A. Goldin L. Kuflik T. Kimchi E. Schach S.R. 《IEEE transactions on pattern analysis and machine intelligence》2004,30(9):601-612
We propose a model that enables software developers to systematically evaluate and compare all possible alternative reuse scenarios. The model supports the clear identification of the basic operations involved and associates a cost component with each basic operation in a focused and precise way. The model is a practical tool that assists developers to weigh and evaluate different reuse scenarios, based on accumulated organizational data, and then to decide which option to select in a given situation. The model is currently being used at six different companies for cost-benefit analysis of alternative reuse scenarios; we give a case study that illustrates how it has been used in practice. 相似文献
84.
We consider probability-theoretic and statistical models and methods for computing the characteristics of dictionary structures. Results of a statistical analysis of several commonly used dictionaries are presented in order to test the adequacy of the computing methods proposed. 相似文献
85.
S. M. Obraztsov G. A. Birzhevoi Yu. V. Konobeev V. A. Solov'ev O. S. Silkina 《Atomic Energy》2004,96(2):111-116
The results of a computational experiment with a neural-net model simulating the effect of the chemical composition on the plastic properties of ÉP-450 steel are presented. It is shown that computer-aided development of reactor steel with prescribed properties is, in principle, possible. 相似文献
86.
87.
88.
89.
90.