全文获取类型
收费全文 | 785187篇 |
免费 | 10830篇 |
国内免费 | 1860篇 |
专业分类
电工技术 | 14437篇 |
综合类 | 844篇 |
化学工业 | 124742篇 |
金属工艺 | 31792篇 |
机械仪表 | 26552篇 |
建筑科学 | 18051篇 |
矿业工程 | 4933篇 |
能源动力 | 20926篇 |
轻工业 | 64420篇 |
水利工程 | 8716篇 |
石油天然气 | 16775篇 |
武器工业 | 100篇 |
无线电 | 89960篇 |
一般工业技术 | 157434篇 |
冶金工业 | 132876篇 |
原子能技术 | 18035篇 |
自动化技术 | 67284篇 |
出版年
2021年 | 8055篇 |
2020年 | 5919篇 |
2019年 | 7455篇 |
2018年 | 12357篇 |
2017年 | 12557篇 |
2016年 | 13416篇 |
2015年 | 8667篇 |
2014年 | 14531篇 |
2013年 | 36562篇 |
2012年 | 22610篇 |
2011年 | 30292篇 |
2010年 | 23946篇 |
2009年 | 26612篇 |
2008年 | 27010篇 |
2007年 | 26198篇 |
2006年 | 23149篇 |
2005年 | 20903篇 |
2004年 | 19890篇 |
2003年 | 19582篇 |
2002年 | 18692篇 |
2001年 | 18091篇 |
2000年 | 17263篇 |
1999年 | 17081篇 |
1998年 | 39336篇 |
1997年 | 28275篇 |
1996年 | 22233篇 |
1995年 | 17048篇 |
1994年 | 15283篇 |
1993年 | 14978篇 |
1992年 | 11771篇 |
1991年 | 11169篇 |
1990年 | 10994篇 |
1989年 | 10594篇 |
1988年 | 10123篇 |
1987年 | 9116篇 |
1986年 | 8819篇 |
1985年 | 10042篇 |
1984年 | 9133篇 |
1983年 | 8617篇 |
1982年 | 7885篇 |
1981年 | 8019篇 |
1980年 | 7574篇 |
1979年 | 7599篇 |
1978年 | 7401篇 |
1977年 | 8324篇 |
1976年 | 10410篇 |
1975年 | 6689篇 |
1974年 | 6531篇 |
1973年 | 6647篇 |
1972年 | 5535篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
O. A. Dolgopolov 《Glass and Ceramics》2005,62(5-6):155-156
Magnetic roll separators on rare-earth magnets are suitable for removing iron impurities from various materials. The advantages
of these magnetic separators over traditional ones are demonstrated.
__________
Translated from Steklo i Keramika, No. 5, p. 33, May, 2005. 相似文献
992.
Phylogenetic scanning: a computer-assisted algorithm for mapping gene conversions and other recombinational events 总被引:1,自引:0,他引:1
An algorithm, 'phylogenetic scanning', is described for mapping gene conversion events where comparative DNA sequence data are available from different species. In this algorithm, sets of hypothetical phylogenetic trees are constructed that describe possible sequence relationships due to gene conversions in different species lineages; these trees are then evaluated by the principle of parsimony at intervals in the sequence alignment. When used to map gene conversion events that occurred between the pair of gamma-globin genes of higher primates, the algorithm gives results nearly identical to those obtained using a tedious manual approach. Suggestions are also provided for adaptation of this procedure to the analysis of other recombination events. 相似文献
993.
Lee C. Chang Ph.D. Associate Professor Director Jeri L. Edwards Senior Manager 《Computers & Industrial Engineering》1991,21(1-4):147-151
Image processing allows the automation of the business transaction, turning “paper factories” into “image factories.” This burgeoning new area of computerization needs new paradigms, theories, and methods to maximize its effectiveness at cutting time and costs. This paper investigates what this new area of computerization can gain from CIM technology. It examines the similarities between the processing of computer images in a paperless business environment and the processing of materials into products in the manufacturing plant. These similarities will allow us to apply mature, well-tested CIM techniques to emerging image factories. 相似文献
994.
995.
996.
We formulate a class of difference schemes for stiff initial-value problems, with a small parameter ε multiplying the first derivative. We derive necessary conditions for uniform convergence with respect to the small parameter ε, that is the solution of the difference scheme uih satisfies |uih−u(xi)| Ch, where C is independent of h and ε. We also derive sufficient conditions for uniform convergence and show that a subclass of schemes is also optimal in the sense that |uih−u(xi)| C min (h, ε). Finally, we show that this class contains higher-order schemes. 相似文献
997.
998.
999.
Bordini Ernest J.; Tucker Jalie A.; Vuchinich Rudy E.; Rudd Edmund J. 《Canadian Metallurgical Quarterly》1986,95(4):346
Assessed whether women self-handicap with alcohol consumption prior to engaging in a social evaluation task, which may be more relevant to their self-esteem than the intellectual tasks used in past self-handicapping studies on substance use. 113 women (aged 19–32 yrs), who were evaluated as normal drinkers, performed either a solvable or an insolvable social judgment task and then received either success feedback or no feedback. Ss received access to alcoholic and nonalcoholic beverages while awaiting a retest. The study terminated before the retest. The self-handicapping hypothesis that noncontingent success would produce relatively greater alcohol consumption was not supported. Regardless of feedback, insolvable test Ss consumed more alcohol than did solvable test Ss. Findings suggest that the hypothesis may be limited as a general model of alcohol consumption in both sexes. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
1000.
An asymptotically efficient autoregressive moving-average (ARMA) spectral estimator is presented, based on the sample covariances of observed time series. The estimate of the autoregressive (AR) part is shown to be identical to the optimal instrumental variable (IV) estimator in [7] although derived here using a different approach. The moving-average (MA) spectral parameter estimate is new. 相似文献