全文获取类型
收费全文 | 37977篇 |
免费 | 2870篇 |
国内免费 | 1507篇 |
专业分类
电工技术 | 1847篇 |
技术理论 | 2篇 |
综合类 | 2285篇 |
化学工业 | 6451篇 |
金属工艺 | 2124篇 |
机械仪表 | 2283篇 |
建筑科学 | 2965篇 |
矿业工程 | 936篇 |
能源动力 | 896篇 |
轻工业 | 2312篇 |
水利工程 | 526篇 |
石油天然气 | 2602篇 |
武器工业 | 211篇 |
无线电 | 4630篇 |
一般工业技术 | 4781篇 |
冶金工业 | 2118篇 |
原子能技术 | 415篇 |
自动化技术 | 4970篇 |
出版年
2024年 | 142篇 |
2023年 | 626篇 |
2022年 | 938篇 |
2021年 | 1398篇 |
2020年 | 1061篇 |
2019年 | 886篇 |
2018年 | 967篇 |
2017年 | 1155篇 |
2016年 | 1045篇 |
2015年 | 1369篇 |
2014年 | 1732篇 |
2013年 | 2220篇 |
2012年 | 2178篇 |
2011年 | 2481篇 |
2010年 | 2246篇 |
2009年 | 2068篇 |
2008年 | 2063篇 |
2007年 | 2048篇 |
2006年 | 2060篇 |
2005年 | 1794篇 |
2004年 | 1228篇 |
2003年 | 1049篇 |
2002年 | 1015篇 |
2001年 | 876篇 |
2000年 | 902篇 |
1999年 | 1093篇 |
1998年 | 948篇 |
1997年 | 828篇 |
1996年 | 821篇 |
1995年 | 629篇 |
1994年 | 547篇 |
1993年 | 379篇 |
1992年 | 340篇 |
1991年 | 255篇 |
1990年 | 194篇 |
1989年 | 168篇 |
1988年 | 137篇 |
1987年 | 104篇 |
1986年 | 77篇 |
1985年 | 58篇 |
1984年 | 57篇 |
1983年 | 30篇 |
1982年 | 37篇 |
1981年 | 24篇 |
1980年 | 18篇 |
1979年 | 11篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1973年 | 5篇 |
1970年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
唐大宏 《计算机工程与设计》1994,(2):60-64,F003,F00
依据物体透视图的人工作图法,本文提出了确定透视变换矩阵的新方法,这种方法基于一组新的参数,而每个参数与透视变换的结果有明显关系,因此便于使用,并给出了计算机作图示例。 相似文献
104.
本文介绍智能控制在回转窑配料系统中的应用情况,并阐述该控制器设计、构成、软件系统特点及现场运行效果。 相似文献
105.
106.
To investigate the pathogenicity of Aspergillus fumigatus mutants lacking putative virulence factors, we have developed a new murine model of invasive pulmonary aspergillosis based on neutropenia, the major factor predisposing patients to this infection. Mice were treated with cyclophosphamide and inoculated by the intranasal route with 5 x 10(3) conidia, a significant reduction from inoculum levels used in previous models. Evidence for the production of the extracellular alkaline protease (Alp) in lung tissue was obtained by using a fungal transformant harboring an alp::lacZ reporter gene fusion. The pathogenicities of single mutant strains lacking either Alp or the ribotoxin restrictocin and of a double mutant strain lacking both proteins were assessed in this infection model. There were no significant differences between the mutant and the wild-type strains in terms of mortality or histological-features. Inoculations with mixtures of conidia showed that the double mutant strain is slightly less virulent than the wild-type strain. We conclude that Alp and restrictocin are not important virulence determinants in pulmonary infection. 相似文献
107.
Cell division in higher eukaryotes is mainly controlled by p34cdc2 or related kinases and by other components of these kinase complexes. We present evidence that cdc2-like kinases also occur in Paramecium. Two polypeptides reacted with an antibody directed against the perfectly conserved PSTAIR region found in cdc2 kinases in other eukaryotes. Only the less abundant peptide bound to p13suc1 from Schizosaccharomyces pombe. Using centrifugal elutriation to select cells on the basis of size, we isolated highly synchronous Paramecium G1 cells. With this procedure, we demonstrated that the p13suc1-associated cdc2-like histone H1 kinase was activated before cell division at the point of commitment to division in Paramecium. Further, we show that Paramecium cdc2-like proteins occurred principally as monomers and that these monomers were active as histone H1 kinases in vitro. 相似文献
108.
109.
A structured genetic algorithm (SGA) approach is developed for robust controller design based on the concept of an H∞ loop-shaping technique and the method of inequalities. Such an SGA is capable of simultaneously searching the orders and coefficients of the precompensator and postcompensator for the weighted plant. It is, therefore, not necessary to predefine the order of compensators as in usual practice. A multiple objective ranking approach is also incorporated so that the design criteria of extreme plants can be easily achieved. The effectiveness of such a technique is illustrated by a high-purity distillation column design example 相似文献
110.
This paper introduces genetic algorithms (GA) as a complete entity, in which knowledge of this emerging technology can be integrated together to form the framework of a design tool for industrial engineers. An attempt has also been made to explain “why” and “when” GA should be used as an optimization tool 相似文献