全文获取类型
收费全文 | 2034篇 |
免费 | 102篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 19篇 |
综合类 | 11篇 |
化学工业 | 431篇 |
金属工艺 | 50篇 |
机械仪表 | 49篇 |
建筑科学 | 90篇 |
矿业工程 | 8篇 |
能源动力 | 57篇 |
轻工业 | 123篇 |
水利工程 | 4篇 |
石油天然气 | 5篇 |
无线电 | 139篇 |
一般工业技术 | 404篇 |
冶金工业 | 370篇 |
原子能技术 | 15篇 |
自动化技术 | 364篇 |
出版年
2023年 | 21篇 |
2022年 | 28篇 |
2021年 | 66篇 |
2020年 | 50篇 |
2019年 | 55篇 |
2018年 | 49篇 |
2017年 | 40篇 |
2016年 | 63篇 |
2015年 | 53篇 |
2014年 | 54篇 |
2013年 | 128篇 |
2012年 | 97篇 |
2011年 | 137篇 |
2010年 | 97篇 |
2009年 | 88篇 |
2008年 | 103篇 |
2007年 | 111篇 |
2006年 | 75篇 |
2005年 | 67篇 |
2004年 | 50篇 |
2003年 | 55篇 |
2002年 | 50篇 |
2001年 | 38篇 |
2000年 | 25篇 |
1999年 | 36篇 |
1998年 | 75篇 |
1997年 | 35篇 |
1996年 | 48篇 |
1995年 | 43篇 |
1994年 | 15篇 |
1993年 | 25篇 |
1992年 | 19篇 |
1991年 | 17篇 |
1990年 | 17篇 |
1989年 | 16篇 |
1988年 | 15篇 |
1987年 | 22篇 |
1986年 | 11篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 4篇 |
1980年 | 10篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1976年 | 20篇 |
1975年 | 5篇 |
1972年 | 4篇 |
1971年 | 6篇 |
排序方式: 共有2139条查询结果,搜索用时 31 毫秒
181.
Ulf Rolander Gerold Weinl Marcus Zwinkels 《International Journal of Refractory Metals and Hard Materials》2001,19(4-6):325-328
The effect of Ta on the structure and mechanical properties of (Ti,Ta,W)(C,N)–Co cermets was investigated. A series of alloys of varying nominal composition were manufactured following normal powder metallurgical procedures. The alloys were characterized and their performance in metal cutting was evaluated. It was found that Ta enhances the resistance to plastic deformation (PD) of this system. By combining sets of alloys, several explanations for this enhancement could be eliminated. Plastic deformation was found to be caused by grain boundary sliding. Ta is believed to influence the interfacial energies of the system, yielding a stronger hard phase skeleton, which restricts grain boundary sliding. 相似文献
182.
The thermal expansion of filaments of CVD SiC was measured parallel and perpendicular to the filament axis. A discontinuity in the expansion versus temperature curve near the melting point of Si indicated the presence of free Si. The magnitude of the discontinuity was used to estimate the amount of the Si in the fibers. The presence of free Si is discussed in relation to the design and maximum-use temperature of SiC-filament-reinforced ceramic composites. 相似文献
183.
184.
Winsauer Peter J.; Delatte Marcus S.; Stevenson Michael W.; Moerschbaecher Joseph M. 《Canadian Metallurgical Quarterly》2002,10(4):392
The nonserotonergic benzodiazepine, triazolam, was compared with two 5-HT1A receptor agonists, 8-OH-DPAT and buspirone, in squirrel monkeys responding under a repeated-acquisition procedure. In each session, subjects acquired a 4-response sequence by responding sequentially on 3 keys in the presence of 4 discriminative stimuli (colors). Response sequences for each session were maintained by food presentation under a second-order fixed-ratio schedule. Errors produced a brief time-out but did not reset the sequence. In general, all of the drugs produced dose-dependent decreases in overall response rate and increases in the percentage of errors as the cumulative dose was increased. Together, these results indicate that 5-HT1A receptor agonists disrupt learning in squirrel monkeys by producing rate-decreasing and error-increasing effects in a manner comparable with the nonserotonergic benzodiazepine triazolam. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
185.
186.
Gail H. Marcus 《Progress in Nuclear Energy》2005,47(1-4):27-31
The mission of the OECD Nuclear Energy Agency (NEA) is to assist its member countries in maintaining and further developing, through international co-operation, the scientific, technological and legal bases required for the safe, environmentally friendly and economical use of nuclear energy for peaceful purposes. In fulfilling that mission, the NEA conducts technical, economic and policy studies in response to the needs and interests of its 28 member countries. In recent years, a number of these studies have addressed various aspects of the next generation of nuclear power plants. This paper will describe some of the major activities recently completed and currently underway that may be of particular interest to the COE-INES program. 相似文献
187.
188.
Methanol-to-olefin (MTO) conversion on microporous silico-aluminophosphates is particularly well-suited for the application of molecular-level concepts to the development of well-defined supported catalysts. The active site of a typical MTO catalyst is a nm-size inorganic cage with an essential organic component. Opportunities for altering the selectivity of such catalysts include tailoring the organic component and modification of the cage with additional inorganic material through ship-in-a-bottle synthesis. The latter possibility has already been realized experimentally by the development of a useful and practical phosphate-modified catalyst. 相似文献
189.
190.
Cella David; Hughes Chanita; Peterman Amy; Chang Chih-Hung; Peshkin Beth N.; Schwartz Marc D.; Wenzel Lari; Lemke Amy; Marcus Alfred C.; Lerman Caryn 《Canadian Metallurgical Quarterly》2002,21(6):564
The Multidimensional Impact of Cancer Risk Assessment (MICRA) is a new tool to measure the specific impact of result disclosure after genetic testing. The authors compared its performance with that of questionnaires measuring general and cancer-specific distress. Participants (158 women) responded 1 month after they received genetic test results. The women were divided into 4 standard clinical test result groups: BRCA1/2 positive, BRCA1/2 negative, panel negative, and true negative. Factor analysis supported the formation of 3 subscales: Distress (6 items, α= .86), Uncertainty (9 items, α= .77), and Positive Experiences (4 items, α= .75). All 3 MICRA subscales differentiated participants who were BRCAI/2 positive from the other 3 groups. MICRA thus helps identify subgroups of vulnerable genetic testing participants. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献