全文获取类型
收费全文 | 32433篇 |
免费 | 1181篇 |
国内免费 | 112篇 |
专业分类
电工技术 | 399篇 |
综合类 | 228篇 |
化学工业 | 5380篇 |
金属工艺 | 665篇 |
机械仪表 | 642篇 |
建筑科学 | 1004篇 |
矿业工程 | 94篇 |
能源动力 | 997篇 |
轻工业 | 4069篇 |
水利工程 | 253篇 |
石油天然气 | 158篇 |
武器工业 | 6篇 |
无线电 | 2351篇 |
一般工业技术 | 4348篇 |
冶金工业 | 9002篇 |
原子能技术 | 251篇 |
自动化技术 | 3879篇 |
出版年
2024年 | 53篇 |
2023年 | 163篇 |
2022年 | 524篇 |
2021年 | 843篇 |
2020年 | 570篇 |
2019年 | 634篇 |
2018年 | 734篇 |
2017年 | 831篇 |
2016年 | 773篇 |
2015年 | 602篇 |
2014年 | 920篇 |
2013年 | 1510篇 |
2012年 | 1342篇 |
2011年 | 1670篇 |
2010年 | 1216篇 |
2009年 | 1270篇 |
2008年 | 1158篇 |
2007年 | 1009篇 |
2006年 | 836篇 |
2005年 | 868篇 |
2004年 | 935篇 |
2003年 | 837篇 |
2002年 | 809篇 |
2001年 | 705篇 |
2000年 | 549篇 |
1999年 | 618篇 |
1998年 | 2872篇 |
1997年 | 1816篇 |
1996年 | 1247篇 |
1995年 | 781篇 |
1994年 | 616篇 |
1993年 | 704篇 |
1992年 | 251篇 |
1991年 | 331篇 |
1990年 | 264篇 |
1989年 | 227篇 |
1988年 | 256篇 |
1987年 | 190篇 |
1986年 | 194篇 |
1985年 | 208篇 |
1984年 | 134篇 |
1983年 | 95篇 |
1982年 | 132篇 |
1981年 | 140篇 |
1980年 | 138篇 |
1979年 | 95篇 |
1978年 | 82篇 |
1977年 | 191篇 |
1976年 | 382篇 |
1975年 | 92篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
1.
Pasquale Stano Tereza Pereira de Souza Paolo Carrara Emiliano Altamura Erica D’Aguanno Margherita Caputo 《先进材料力学与结构力学》2015,22(9):748-759
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations. 相似文献
2.
3.
4.
5.
6.
7.
8.
9.
10.
Martins Silvia S.; Mazzotti Guido; Chilcoat Howard D. 《Canadian Metallurgical Quarterly》2006,14(3):275
Background: Despite increases in ecstasy (MDMA) use in the United States, little is known about characteristics linked with recent-onset ecstasy use, especially psychiatric symptoms and deviant behaviors. Aims: To test whether individuals with high levels of other drug use are more likely to be recent-onset ecstasy users; to test whether psychiatric symptoms in adults are associated with recent-onset ecstasy use; to explore the association between recent-onset ecstasy use and concomitant deviant behaviors in adolescents and adults. Methods: Data from the 2001 National Survey on Drug Use and Health. Findings: Recent-onset ecstasy use was significantly more likely to occur among adolescents and adults (18-34 years old) who engaged in deviant behaviors during the past year as compared with those who did not engage in deviant behaviors during the past year. Higher levels of deviancy indicated a higher likelihood of being a recent-onset ecstasy user, and associations were strongest with nonviolent deviant behaviors such as selling illegal drugs and stealing. Associations between deviant behaviors and recent-onset ecstasy use were similar in strength to associations between deviant behaviors and recent-onset cocaine and marijuana use, respectively. Adults who had past-year psychiatric symptoms (both depressive and panic symptoms) were twice as likely to be recent-onset ecstasy users as compared with those without past-year psychiatric symptoms. Greater levels of drug involvement increased the odds of being a recent-onset ecstasy user. Conclusion: Recent-onset ecstasy use seems to be associated with a range of other behavioral problems and may reflect one aspect of a larger problem behavior syndrome. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献