全文获取类型
收费全文 | 46302篇 |
免费 | 2609篇 |
国内免费 | 1284篇 |
专业分类
电工技术 | 1449篇 |
技术理论 | 4篇 |
综合类 | 2783篇 |
化学工业 | 11366篇 |
金属工艺 | 6550篇 |
机械仪表 | 1193篇 |
建筑科学 | 6332篇 |
矿业工程 | 1599篇 |
能源动力 | 1121篇 |
轻工业 | 4174篇 |
水利工程 | 1792篇 |
石油天然气 | 1706篇 |
武器工业 | 146篇 |
无线电 | 833篇 |
一般工业技术 | 3453篇 |
冶金工业 | 4792篇 |
原子能技术 | 258篇 |
自动化技术 | 644篇 |
出版年
2024年 | 166篇 |
2023年 | 432篇 |
2022年 | 1100篇 |
2021年 | 1301篇 |
2020年 | 1221篇 |
2019年 | 872篇 |
2018年 | 874篇 |
2017年 | 1125篇 |
2016年 | 1144篇 |
2015年 | 1279篇 |
2014年 | 2447篇 |
2013年 | 2340篇 |
2012年 | 3115篇 |
2011年 | 3341篇 |
2010年 | 2850篇 |
2009年 | 2971篇 |
2008年 | 2264篇 |
2007年 | 3130篇 |
2006年 | 3098篇 |
2005年 | 2617篇 |
2004年 | 2243篇 |
2003年 | 2085篇 |
2002年 | 1695篇 |
2001年 | 1328篇 |
2000年 | 1052篇 |
1999年 | 804篇 |
1998年 | 626篇 |
1997年 | 502篇 |
1996年 | 390篇 |
1995年 | 368篇 |
1994年 | 257篇 |
1993年 | 194篇 |
1992年 | 183篇 |
1991年 | 147篇 |
1990年 | 89篇 |
1989年 | 122篇 |
1988年 | 69篇 |
1987年 | 64篇 |
1986年 | 47篇 |
1985年 | 44篇 |
1984年 | 44篇 |
1983年 | 35篇 |
1982年 | 19篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1966年 | 9篇 |
1965年 | 7篇 |
1964年 | 9篇 |
1959年 | 7篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
电去离子(EDI)技术在热电厂水处理中的应用 总被引:8,自引:0,他引:8
电去离子 (Electrodeionization简称EDI) ,是一种将膜分离技术与离子交换技术有机结合起来去除水中离子获得低电导率产品水的新型水处理技术 ,在电力、电子、医药、化工、冶金、机械、化妆品、电镀电解、食品饮料、纺织印染等多个领域具有广泛的应用空间 ,本文简要介绍了这种新型水处理技术的原理、特点及在热电厂化学水处理中的成功应用情况 相似文献
52.
湛江电厂1号发电机定子冷却水处理方式的改造 总被引:1,自引:0,他引:1
简述发电机铜导线腐蚀机理,湛江电厂1号发电机定子冷却处理方式改造前后各自的特点。比较新旧两种方式水质处理效果、安全性、经济性。采用超净化装置后,解决了原来处理方式的所有缺点,水质达到质量标准, 创造良好的经济效益,值得推广改造和借鉴。 相似文献
53.
《中国稀土学报(英文版)》2005,(4)
Effects of La(NO_3)_3 Treatment on Photocattalytic Activity of TiO_2 Films Prepared by Micro-Arc Oxidation 相似文献
54.
The marshland upwelling system (MUS) was installed on private camps in the Grand Bay National Estuarine Research Reserve, Moss Point, Mississippi. The system was evaluated for its effectiveness in removing fecal coliforms from settled, raw wastewater. A suite of studies was performed at flow rates of 1.9, 2.8, and 5.5 L/min and an injection frequency of 30 min every 3 h to investigate fecal coliform removal. An additional study was performed at a flow rate of 2.8 L/min and an injection frequency of 15 min every hour. Overall, the MUS consistently maintained fecal concentrations below effluent regulatory standards for shellfish harvesting waters (14 most probable number of colonies per 100 mL). Mean influent concentrations of 55,269±2,218,016 colony forming units (CFU)/100 mL were reduced to effluent counts of 2.7±14.07 CFU/100 mL (observed in the 1.5 m wells). Three- to four-log reductions in influent counts were observed over the initial 1.4 vector?m from the injection well. The overall removal followed a first-order decay relationship with respect to vector distance, resulting in removal rate constants ranging from 5.6 to 6.6/m and predicted surface concentrations approaching 0 CFU/100 mL. The 2.8 L/min for 30 min every 3 h treatment provided the best effluent quality. 相似文献
55.
The relationship between treatment outcome and the extent to which participants completed homework assignments was evaluated among 60 cocaine-dependent individuals assigned to cognitive-behavioral therapy (CBT). Homework was assigned in 72% of all sessions and initiated by participants in 48% of the sessions in which it was assigned. Completion of homework was unrelated to participants' baseline characteristics and several indicators of treatment compliance. Participants who completed more homework assignments demonstrated significantly greater increases in the quantity and quality of their coping skills and used significantly less cocaine during treatment and through a 1-year follow-up. These data suggest that the extent to which participants are willing to complete extrasession assignments may be an important mediator of response to CBT. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
56.
Lutz Wolfgang; Leach Chris; Barkham Michael; Lucock Mike; Stiles William B.; Evans Chris; Noble Rachael; Iveson Steve 《Canadian Metallurgical Quarterly》2005,73(5):904
This study extended client-focused research by using the nearest neighbor (NN) approach, a client-specific sampling and prediction strategy derived from research on alpine avalanches. Psychotherapy clients (N = 203) seen in routine practice settings in the United Kingdom completed a battery of intake measures and then completed symptom intensity ratings before each session. Forecasts of each client's rate of change and session-by-session variability were computed on the basis of that client's NNs (n = 10-50 in different comparisons). Alternative forecasts used linear or log-linear slopes and were compared with an alternative prediction strategy. Results showed that the NN approach was superior to the alternative model in predicting rate of change, though the advantage was less clear for predicting variability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
57.
Persky Irena; Spring Bonnie; Wal Jillon S. Vander; Pagoto Sherry; Hedeker Donald 《Canadian Metallurgical Quarterly》2005,24(2):153
The authors tested whether adherence to simultaneous health behavior changes was unitary or domain specific among 76 women who modified smoking, eating, and physical activity to accomplish smoking cessation plus weight control. Random-effects regression analyses showed that adherence to both smoking and diet plans declined linearly and covaried positively; their association tended to grow stronger over time. In contrast, physical activity plan adherence did not change over time and was unrelated to other domains. At the end of treatment, 65%, 30.5%, and 25% adhered well or excellently to smoking, diet, and activity treatments, respectively. Findings support both unitary and domain-specific aspects of adherence and suggest that among smokers, smoking and eating behaviors may have similarities unshared by physical activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
58.
本文研究了热处理工艺对2.25C r1M oR钢组织和力学性能的影响。结果表明,该钢在780℃时可获得良好的强韧化效果和较高的抗回火脆性能力,在此基础上得到了该钢板生产制造的热处理工艺参数。实践证明,该工艺合理可行。 相似文献
59.
60.
Adhesion of plasma-deposited optical and protective coatings, such as amorphous hydrogenated silicon nitride, SiN1.3, on polymethyl-methacrylate (PMMA) substrates has been found to be limited by a cohesive failure inside the PMMA bulk. Using direct exposure to a low pressure plasma in helium or to vacuum ultraviolet (VUV) radiation generated from plasma, the adhesion of SiN1.3 at high humidity and elevated temperature has been substantially increased. Using a multitechnique analytical approach, the enhanced adhesion was attributed to the initial etching of the weak boundary layer followed by formation of a crosslinked, graded, mechanically stabilized layer in the interfacial region (interphase), which possesses a physical thickness of 50 to 100 nm and a microhardness of about 2 GPa. 相似文献