全文获取类型
收费全文 | 10257篇 |
免费 | 850篇 |
国内免费 | 720篇 |
专业分类
电工技术 | 654篇 |
综合类 | 1375篇 |
化学工业 | 1431篇 |
金属工艺 | 689篇 |
机械仪表 | 667篇 |
建筑科学 | 922篇 |
矿业工程 | 372篇 |
能源动力 | 498篇 |
轻工业 | 552篇 |
水利工程 | 247篇 |
石油天然气 | 421篇 |
武器工业 | 52篇 |
无线电 | 1090篇 |
一般工业技术 | 876篇 |
冶金工业 | 539篇 |
原子能技术 | 101篇 |
自动化技术 | 1341篇 |
出版年
2024年 | 20篇 |
2023年 | 54篇 |
2022年 | 70篇 |
2021年 | 113篇 |
2020年 | 146篇 |
2019年 | 167篇 |
2018年 | 201篇 |
2017年 | 165篇 |
2016年 | 201篇 |
2015年 | 235篇 |
2014年 | 245篇 |
2013年 | 281篇 |
2012年 | 293篇 |
2011年 | 232篇 |
2010年 | 292篇 |
2009年 | 268篇 |
2008年 | 392篇 |
2007年 | 393篇 |
2006年 | 384篇 |
2005年 | 285篇 |
2004年 | 597篇 |
2003年 | 1295篇 |
2002年 | 2127篇 |
2001年 | 1840篇 |
2000年 | 730篇 |
1999年 | 385篇 |
1998年 | 85篇 |
1997年 | 74篇 |
1996年 | 66篇 |
1995年 | 41篇 |
1994年 | 30篇 |
1993年 | 21篇 |
1992年 | 25篇 |
1991年 | 19篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
81.
82.
简述了染料释放化合物的发展过程 ,并由此引出一当量成色剂的概念 ,叙述了一当量成色剂应用和发展 ,对一当量成色剂应用前景做了预测。 相似文献
83.
84.
85.
单塔精馏生产优级品乙酸的研究 总被引:1,自引:0,他引:1
用理论计算与实验相结合的办法 ,采用单塔精馏生产优级品乙酸 ,以降低能耗 ,减少物料损失 ,提高产品收率 ,缩短生产周期 ,避免了双塔精馏所造成的设备与能源的浪费。在国内首次成功研究了单塔精馏生产优级品乙酸的生产工艺。 相似文献
86.
Graft copolymerization of acrylic acid (AA) onto polyphenylene sulfide (PPS) nonwoven initiated by low temperature plasma was studied. The effects of various conditions on graft reaction and the grafting rate were investigated. SEM images showed that PPS nonwoven was grafted, and the graft copolymerization only occurred on the surface of PPS. It may be due to the chain transference going with the graft copolymerization. It was found that with the increasing of plasma power, treatment time, space between electrodes, monomer concentration, and temperature of graft polymerization, the grafting rate increased at first, went to the top, and then decreased. The PPS nonwoven surface graft reaction could be optimized by the following processing conditions: 120 s of plasma treatment time, 50 W of plasma power, 1.5 cm of space between electrodes, 30% (w/w) of monomer concentration, and 50°C of temperature of graft polymerization. Measurement of XPS showed that the peak of C1s of graft polyacrylic acid was existed, and the peak area increased with the increase of the grafting rate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5884–5889, 2006 相似文献
87.
Dielectrophoresis (DEP) allows to moving neutral or charged particles in liquids by supplying a non-uniform electric field. When using alternating current and insulated electrodes, this is possible in conducting media such as aqueous solutions. However, relatively high field strength is required that is discussed to induce also an undesired Joule heating effect. In this paper, we demonstrate boundary conditions for avoiding this side effect and suggest a novel design of an interdigitated electrode (IDE) configuration to reduce the power consumption. Numerical simulation using OpenFOAM demonstrated that, when replacing conventional plate IDE by cylindrical micro-IDE in microchannel systems, the dielectrophoretic force field, i.e., the electric field gradient squared, becomes stronger and more homogeneously distributed along the electrodes array. Also the resulting particle DEP velocities were highest for the cylindrical IDE. The simulations were experimentally confirmed by measuring velocity of resin particle located at the subsurface of demineralized water. Surprisingly the fluid flow induced by electrothermal effect turned out to be negligible in microchannels when compared to the DEP effect and becomes dominant only for distances between particle and IDE larger than 6,000 μm. The well-agreed experimental and simulation results allow for predicting particle motion. This can be expected to pave the way for designing DEP microchannel separators with high throughput and low energy consumption. 相似文献
88.
89.
Identification of organochlorines and organobromines in coals 总被引:1,自引:0,他引:1
Xian-Yong Wei Xiao-Hua Wang Zhi-Min Zong Zhong-Hai Ni Li-Fang Zhang Ya-Fei Ji Ke-Chang Xie Chul Wee Lee Zhen-Xue Liu Nai-Bo Chu Jiao-Ying Cui 《Fuel》2004,83(17-18):2435-2438
Four Chinese bituminous coals were extracted with CS2, n-hexane, benzene, methanol, acetone, tetrahydrofuran (THF) and THF/methanol (1: 3 vol/vol) mixed solvent sequentially. The resulting 28 extracts were analyzed with GC/MS. Six organochlorines (OCs) and two organobromines (OBs) were identified in eight extracts from the coals. Our experiments provide, for the first time, the information on the molecular structure of OCs and OBs in coals. 相似文献
90.