全文获取类型
收费全文 | 8110篇 |
免费 | 833篇 |
国内免费 | 494篇 |
专业分类
电工技术 | 836篇 |
综合类 | 555篇 |
化学工业 | 907篇 |
金属工艺 | 647篇 |
机械仪表 | 541篇 |
建筑科学 | 486篇 |
矿业工程 | 251篇 |
能源动力 | 148篇 |
轻工业 | 666篇 |
水利工程 | 207篇 |
石油天然气 | 368篇 |
武器工业 | 125篇 |
无线电 | 629篇 |
一般工业技术 | 531篇 |
冶金工业 | 1457篇 |
原子能技术 | 132篇 |
自动化技术 | 951篇 |
出版年
2024年 | 72篇 |
2023年 | 157篇 |
2022年 | 291篇 |
2021年 | 366篇 |
2020年 | 260篇 |
2019年 | 241篇 |
2018年 | 188篇 |
2017年 | 221篇 |
2016年 | 219篇 |
2015年 | 312篇 |
2014年 | 376篇 |
2013年 | 474篇 |
2012年 | 588篇 |
2011年 | 579篇 |
2010年 | 526篇 |
2009年 | 474篇 |
2008年 | 472篇 |
2007年 | 474篇 |
2006年 | 433篇 |
2005年 | 313篇 |
2004年 | 240篇 |
2003年 | 191篇 |
2002年 | 149篇 |
2001年 | 130篇 |
2000年 | 129篇 |
1999年 | 153篇 |
1998年 | 391篇 |
1997年 | 260篇 |
1996年 | 176篇 |
1995年 | 134篇 |
1994年 | 106篇 |
1993年 | 73篇 |
1992年 | 19篇 |
1991年 | 22篇 |
1990年 | 28篇 |
1989年 | 16篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1977年 | 47篇 |
1976年 | 85篇 |
1975年 | 3篇 |
1966年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有9437条查询结果,搜索用时 8 毫秒
1.
2.
Guangbo Zeng Dongqing Zhang Liuming Yan Baohua Yue Ting Pan Yidong Hu Shufa He Hongbin Zhao Jiujun Zhang 《International Journal of Hydrogen Energy》2021,46(39):20664-20677
Side-chain optimized poly (2,6-dimethyl-1,4-phenylene oxide)-g-poly (styrene sulfonic acid) (PPO-g-PSSA) is designed with balanced water-resistance and sulfonation degree. The PPO-g-PSSA is synthesized by controlled atom-transfer radical polymerization (ATRP) from brominated poly (2,6-dimethyl-1,4-phenylene oxide) (PPO-xBr) and ethyl styrene-4-sulfonate and followed by hydrolysis. A series of PPO-g-PSSA are prepared possessing different bromination degree (x) of PPO-xBr and polymerization degree (m) of the side-chains and the water-resistances of the fabricated membranes are investigated. The results show that a PPO-g-PSSA at relatively low x (x < 0.2) and high m (m > 4) exhibits good balance between the water-resistance and the sulfonation degree. Namely, it displays suitable proton conductivity with compromised water-resistance. Moreover, a maximum ion exchange capacity (IEC) of 3.24 mmol g?1 is reached without the sacrifice of water-resistance. In addition, PPO-g-0.08PSSA-13 and PPO-g-0.14PSSA-4 are chosen characterized by thermogravimetric analysis, proton conductivities and mechanical properties. At 90% RH, the optimized PPO-g-0.08PPSA-13 possesses a proton conductivity of 37.9 mS cm?1 at 40 °C and 45.5 mS cm?1 at 95 °C, respectively. 相似文献
3.
4.
环境保护地理信息系统的设计 总被引:8,自引:0,他引:8
本文主要介绍基于计算机网络的通用型环境保护地理信息系统的功能和实现方法。 相似文献
5.
6.
7.
8.
Comparison evaluation of the methods of treatment was based on the analysis of the results of management of 347 patients with general purulent decompensated peritonitis with polyorganic insufficiency. The efficacy of closed drainage in 98 patients, continuous flow irrigation (dialysis) in 126, stage programmed irrigation and inspection of the abdominal cavity in 99, and open drainage in 24 patients was compared. The causes of peritonitis were: complications after acute surgical diseases (in 156 cases), in planned operations (59), and in obstetrical and gynecological diseases (132). Most of the patients were brought to the clinic from other hospitals because of unsuccessful treatment of peritonitis and absence of means for performing hemodialysis and management of polyorganic insufficiency. The incidence of the last-named reached 71.0 to 91.0% in the different groups of patients. In monotypic complex treatment, stage programmed irrigation was marked by a much lesser number of abscesses and other complications and a lower mortality (20.2%) as compared to flow irrigation (30.0%, closed drainage (27.5%), and open (laparostomy) treatment (37.5%). Despite the very serious contingent of patients, total mortality (27.0%) in the application of the indicated methods was quite low. 相似文献
9.
10.