全文获取类型
收费全文 | 24875篇 |
免费 | 919篇 |
国内免费 | 33篇 |
专业分类
电工技术 | 329篇 |
综合类 | 38篇 |
化学工业 | 5664篇 |
金属工艺 | 394篇 |
机械仪表 | 481篇 |
建筑科学 | 1315篇 |
矿业工程 | 103篇 |
能源动力 | 626篇 |
轻工业 | 1898篇 |
水利工程 | 233篇 |
石油天然气 | 71篇 |
无线电 | 1823篇 |
一般工业技术 | 4536篇 |
冶金工业 | 4566篇 |
原子能技术 | 198篇 |
自动化技术 | 3552篇 |
出版年
2023年 | 214篇 |
2022年 | 361篇 |
2021年 | 569篇 |
2020年 | 339篇 |
2019年 | 432篇 |
2018年 | 538篇 |
2017年 | 464篇 |
2016年 | 634篇 |
2015年 | 558篇 |
2014年 | 754篇 |
2013年 | 1425篇 |
2012年 | 1171篇 |
2011年 | 1520篇 |
2010年 | 1080篇 |
2009年 | 1021篇 |
2008年 | 1153篇 |
2007年 | 1089篇 |
2006年 | 948篇 |
2005年 | 763篇 |
2004年 | 750篇 |
2003年 | 661篇 |
2002年 | 569篇 |
2001年 | 434篇 |
2000年 | 365篇 |
1999年 | 403篇 |
1998年 | 760篇 |
1997年 | 558篇 |
1996年 | 448篇 |
1995年 | 412篇 |
1994年 | 377篇 |
1993年 | 366篇 |
1992年 | 275篇 |
1991年 | 196篇 |
1990年 | 270篇 |
1989年 | 261篇 |
1988年 | 216篇 |
1987年 | 224篇 |
1986年 | 226篇 |
1985年 | 265篇 |
1984年 | 224篇 |
1983年 | 223篇 |
1982年 | 208篇 |
1981年 | 194篇 |
1980年 | 168篇 |
1979年 | 194篇 |
1978年 | 164篇 |
1977年 | 187篇 |
1976年 | 235篇 |
1975年 | 161篇 |
1974年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Thomas Kristenson 《Network Security》2004,2004(3):19-20
Two serious flaws in popular client firewall software have been uncovered in February 相似文献
32.
Everyday memory performance was examined longitudinally in 2 groups of Ss meeting the diagnostic criteria for age-associated memory impairment (AAMI). One group of 157 participants in a drug trial for reversing memory loss in AAMI was tested over multiple sessions. The other group of 75 persons did not participate in a drug trial and thus was tested only twice. Both groups were retested for longitudinal follow-up about 4 yrs after initial session. Follow-up test performance remained fairly stable relative to initial performance in both groups. The drug study group showed large practice effects during the course of the drug studies, but these effects subsided after the drug studies' end. Implications regarding memory decline in the normal elderly and neuropsychological measurement issues are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
33.
Thomas F. Barry 《Fire Technology》1991,27(2):186-188
Published in 1989, 585 pages, $180; Available from the American Institute of Chemical Engineers, 345 East 47th St., Publication Sales Department, New York, NY 10017. 相似文献
34.
35.
Crook Thomas H.; Youngjohn James R.; Larrabee Glenn J.; Salama Maurice 《Canadian Metallurgical Quarterly》1992,6(2):123
Performance on computer-simulated, everyday memory tasks was found to deteriorate with age in 434 Belgian (aged 14–88 yrs) and 434 American Ss matched on gender and age. This age-related memory decline was reasonably consistent across samples. Difficulties in cross-cultural research and the advantages of ecologically valid measurement instruments are discussed. Instruments included a grocery list selective reminding test, the Wechsler Memory Scale, the Benton Visual Retention Test, and the Wechsler Adult Intelligence Scale (WAIS). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
36.
The gas flow sputter technique was invented a few years ago particularly for the inexpensive fabrication of sophisticated ceramic layers. Meanwhile, it has matured and become increasingly powerful. Today it is on the verge of being applied in industrial fabrication processes. The present article gives an overview over the method, its characteristics and the numerous applications. 相似文献
37.
38.
Thomas Deiß 《International Journal on Software Tools for Technology Transfer (STTT)》2008,10(4):347-352
When deploying TTCN-3 at Nokia, we converted two TTCN-2 test systems to TTCN-3. We explain to which extend we have been able
to do the conversion automatically. The conversion tool used provided a syntactically and semantically correct conversion
of the TTCN-2 code. We define some improvements made on the tool to increase readability and maintainability of the resulting
code. We cover aspects of converting also the non-TTCN-2 parts and describe the experiences we made as a set of lessons learnt. 相似文献
39.
In this paper, we present the findings from an extensive study of the use of virtual reality (VR) models in large construction projects. The study includes two parts: The first part presents a quantitative questionnaire designed to investigate how VR models are experienced and assessed by the workforce at a building site. The second part includes a qualitative field survey of how VR models can be applied and accepted by professionals in the design and planning process of a large pelletizing plant. Through mainly studying persons who had little or no experience with advanced information technology (IT), we hoped to reveal the attitudes of the average person working at a construction site rather than of an IT expert. In summary, the study shows that the VR models in both projects have been very useful and well accepted by the users. Today’s information flow is, from a general point of view, considered to be insufficient and the hypothesis is that using VR models in the construction process have the potential to minimize waste of resources and improve the final result. 相似文献
40.
通过理论分析和实验研究液晶分子附着能和液晶盒间隙对响应时间(τ0)的影响。用液晶盒有效间隙法和表面动力学方程法两种方法推出分析公式,由这两种方法推出的结果是一致的。实验数据与简化方程τ0-dx基本拟合(其中d是液晶盒的间隙,x是指数)。在两种极端的(极大或极小)附着能极限下,指数x分别接近2和1。这个结论有助于优化液晶显示器件的应用。 相似文献