全文获取类型
收费全文 | 654293篇 |
免费 | 7003篇 |
国内免费 | 1115篇 |
专业分类
电工技术 | 11753篇 |
综合类 | 552篇 |
化学工业 | 102968篇 |
金属工艺 | 27747篇 |
机械仪表 | 20909篇 |
建筑科学 | 14483篇 |
矿业工程 | 5158篇 |
能源动力 | 16047篇 |
轻工业 | 50901篇 |
水利工程 | 8341篇 |
石油天然气 | 18426篇 |
武器工业 | 42篇 |
无线电 | 68277篇 |
一般工业技术 | 135155篇 |
冶金工业 | 112195篇 |
原子能技术 | 17329篇 |
自动化技术 | 52128篇 |
出版年
2021年 | 6048篇 |
2019年 | 5822篇 |
2018年 | 10243篇 |
2017年 | 10422篇 |
2016年 | 10938篇 |
2015年 | 6732篇 |
2014年 | 11482篇 |
2013年 | 29339篇 |
2012年 | 17657篇 |
2011年 | 23653篇 |
2010年 | 19004篇 |
2009年 | 21212篇 |
2008年 | 21532篇 |
2007年 | 21184篇 |
2006年 | 18454篇 |
2005年 | 16776篇 |
2004年 | 15953篇 |
2003年 | 15568篇 |
2002年 | 15128篇 |
2001年 | 14737篇 |
2000年 | 14135篇 |
1999年 | 13862篇 |
1998年 | 32331篇 |
1997年 | 23353篇 |
1996年 | 18119篇 |
1995年 | 13874篇 |
1994年 | 12514篇 |
1993年 | 12333篇 |
1992年 | 9581篇 |
1991年 | 9364篇 |
1990年 | 9262篇 |
1989年 | 8934篇 |
1988年 | 8626篇 |
1987年 | 7880篇 |
1986年 | 7651篇 |
1985年 | 8555篇 |
1984年 | 7800篇 |
1983年 | 7533篇 |
1982年 | 6800篇 |
1981年 | 6989篇 |
1980年 | 6715篇 |
1979年 | 6912篇 |
1978年 | 6904篇 |
1977年 | 7519篇 |
1976年 | 9450篇 |
1975年 | 6289篇 |
1974年 | 6094篇 |
1973年 | 6203篇 |
1972年 | 5396篇 |
1971年 | 4975篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
Using the improved expression of the defect pool model proposed by Powell and Deane we match the experimental current-voltage and the spectral response characteristic curves of hydrogenated amorphous silicon solar cells. We compare the electrical parameters resulting from using the different defect pool models published in the literature and from assuming a uniform density of dangling bond in every device layer. We discuss the applicability of the algorithm derived by Schumm for the stabilized state exploring its sensitivity to the sample history. Finally we propose an expression for stabilized cells adapting Schumm's ideas to the expression derived by Powell and Deane. 相似文献
973.
Published data on the preparation procedures, stability, and complexation of U(III) in aqueous solutions are summarized and correlated. Reactions with inorganic and organic free radicals studied by the flash radiolysis method, the spectroscopic properties, the extraction and ion-exchange behavior of U(III), and methods for isolation of solid U(III) compounds from aqueous solutions are discussed. 相似文献
974.
975.
Among engineers and scientists, MATLAB is one of the most popular computational packages. Part of MATLAB's popularity stems from its simple, yet sophisticated, graphics capabilities. While basic plots are relatively easy to obtain, specialized plots require a little more effort to produce. This article introduces MATLAB's Handle Graphics, which provides a mechanism to fully control and customize graphics objects in MATLAB. With a basic understanding of Handle Graphics, users can produce plots that meet the unique needs and quality standards commonly required by the profession, several examples are presented to illustrate the concepts. 相似文献
976.
977.
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
978.
979.
980.
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