全文获取类型
收费全文 | 19465篇 |
免费 | 1528篇 |
国内免费 | 479篇 |
专业分类
电工技术 | 619篇 |
综合类 | 1045篇 |
化学工业 | 9202篇 |
金属工艺 | 240篇 |
机械仪表 | 328篇 |
建筑科学 | 1332篇 |
矿业工程 | 148篇 |
能源动力 | 2639篇 |
轻工业 | 1605篇 |
水利工程 | 157篇 |
石油天然气 | 488篇 |
武器工业 | 21篇 |
无线电 | 282篇 |
一般工业技术 | 2632篇 |
冶金工业 | 313篇 |
原子能技术 | 121篇 |
自动化技术 | 300篇 |
出版年
2024年 | 73篇 |
2023年 | 351篇 |
2022年 | 669篇 |
2021年 | 822篇 |
2020年 | 731篇 |
2019年 | 641篇 |
2018年 | 444篇 |
2017年 | 579篇 |
2016年 | 512篇 |
2015年 | 514篇 |
2014年 | 1008篇 |
2013年 | 996篇 |
2012年 | 1501篇 |
2011年 | 1457篇 |
2010年 | 1190篇 |
2009年 | 1101篇 |
2008年 | 951篇 |
2007年 | 1250篇 |
2006年 | 1022篇 |
2005年 | 943篇 |
2004年 | 807篇 |
2003年 | 733篇 |
2002年 | 530篇 |
2001年 | 453篇 |
2000年 | 425篇 |
1999年 | 368篇 |
1998年 | 297篇 |
1997年 | 233篇 |
1996年 | 184篇 |
1995年 | 127篇 |
1994年 | 140篇 |
1993年 | 122篇 |
1992年 | 89篇 |
1991年 | 61篇 |
1990年 | 36篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1951年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
13.
分析并列举了离子交换膜在使用过程中鼓泡的原因,阳极液质量浓度;pH值;阴极液质量浓度;电流密度;开停车及盐水质量等因素都可以造成膜鼓泡,形成针孔。提出了相应的预防措施。 相似文献
14.
我国烧碱生产技术概况 总被引:2,自引:0,他引:2
介绍了我国氯碱行业近几年来的发展情况:分析了我国烧碱生产的工艺技术现状。指出了为缩短与世界先进国家的差距需要加快开发关键设备和高性能的离子膜,加强管理。 相似文献
15.
16.
介绍了快速高效隔膜压滤机的主要性能参数和特点 ;分析了压滤机在煤泥水处理系统中的应用情况和运行结果 ;应用快速高效隔膜压滤机对煤泥水处理系统进行改造后获得了较好的经济及社会效益 相似文献
17.
This paper presents a mathematical model based on the reaction rate expressions to describe the displacement of methane conversion in the steam reforming. The effect of several parameters including weight hourly space velocity (WHSV), load-to-surface ratio, reaction pressure, hydrogen partial pressure in permeate side and reaction temperature were investigated. Simulation and experimental results showed that a conversion higher than 80% could be achieved in a palladium membrane reactor at reaction temperature of 500 °C relative to 850 °C in a conventional fixed bed reactor (FBR). Besides, the yield of CO (<2%) in membrane reactor was much lower than that (>50%) in the FBR, which indicated the significant depression of CO production in use of membrane reactor. 相似文献
18.
V.V. Zyryanov N.F. Uvarov V.A. Sadykov Y.V. Frolova G.M. Alikina A.I. Lukashevich M.I. Ivanovskaya J.M. Criado S. Neophytides 《Catalysis Today》2005,104(2-4):114-119
Nanopowders of LaGaO3- and LaMnO3-based complex perovskites (P) and ceria-based fluorites (F) were prepared by mechanosynthesis. Compatible nanocomposites F + P and P + P with mixed ion and electron conducting (MIEC) properties were prepared and sintered at moderate temperatures up to dense ceramics. The obtained materials were studied by means of XRD, SEM, TEM, electrical conductivity measurements, temperature programmed (TP) reduction/oxidation and preliminary estimations of permeability were obtained. A new strategy based on the advantages of the mechanochemical ceramic approach is proposed to design multilayer ceramic membranes for CMR. Casting technology and one-step sintering were used for the production of thin film membranes with MIEC properties on porous substrates. The coarse fraction of as-milled powders from agglomerates with density 70% was used for the porous substrate, and fine fractions of aggregates with sizes <1 μm were used in preparation of composites for thin dense films. Ceria-based composites prepared by the Pechini route and/or mechanochemical method are proposed as materials for protecting thin films. 相似文献
19.
钯-银合金膜分离氢气的研究 总被引:1,自引:0,他引:1
采用厚为50μm的Pd/Ag(23)合金膜进行了氢气渗透系数的测定和H_2/N_2混和气分离的研究,得出温度、压力、膜厚、进料气流量、膜的预处理和再活化及膜表面中毒等因素对氢气渗透的影响。分离H_2/N_2混和气可获得高纯氢气。 相似文献
20.
Poly (vinyl butyral) (PVB) hollow fiber membranes were fabricated via thermally induced phase separation (TIPS). The effects of coagulation bath temperature (CBT) on the structure and performance of membranes were investigated in detail. The morphologies of the membranes were studied by scanning electron microscopy (SEM), the performances of water permeability, rejection, breaking strength and elongation were measured, respectively. The results indicate that all the membranes have the asymmetric morphology and the thickness of the skin layer decreases and the pore size of the outer layer increases with the increase of CBT. The permeability of membranes prepared at air gap 1.0 cm and take-up speed 0.253 m/s increases from 1.047×10-7 to 5.909×10-7 m3/(m2·s-kPa) with the CBT increasing from 20 ℃ to 40℃, and sharply increases to 35.226×10 7 m3/(m2.s.kPa)once the CBT arrives at 50 ℃. While the carbonic ink rejections have no significant decrease, totally exceed 98%, but that of acid-maleic acid copolymer greatly decreases with the increase of CBT. Both the breaking strength and elongation decrease with the increase of CBT. 相似文献