全文获取类型
收费全文 | 30154篇 |
免费 | 2218篇 |
国内免费 | 1105篇 |
专业分类
电工技术 | 1468篇 |
技术理论 | 2篇 |
综合类 | 1707篇 |
化学工业 | 5160篇 |
金属工艺 | 1842篇 |
机械仪表 | 1987篇 |
建筑科学 | 2370篇 |
矿业工程 | 1003篇 |
能源动力 | 788篇 |
轻工业 | 1718篇 |
水利工程 | 531篇 |
石油天然气 | 2064篇 |
武器工业 | 213篇 |
无线电 | 3208篇 |
一般工业技术 | 3691篇 |
冶金工业 | 1611篇 |
原子能技术 | 353篇 |
自动化技术 | 3761篇 |
出版年
2024年 | 120篇 |
2023年 | 549篇 |
2022年 | 892篇 |
2021年 | 1244篇 |
2020年 | 1031篇 |
2019年 | 781篇 |
2018年 | 955篇 |
2017年 | 968篇 |
2016年 | 923篇 |
2015年 | 1141篇 |
2014年 | 1434篇 |
2013年 | 1779篇 |
2012年 | 1874篇 |
2011年 | 1902篇 |
2010年 | 1717篇 |
2009年 | 1678篇 |
2008年 | 1566篇 |
2007年 | 1544篇 |
2006年 | 1651篇 |
2005年 | 1369篇 |
2004年 | 882篇 |
2003年 | 838篇 |
2002年 | 746篇 |
2001年 | 625篇 |
2000年 | 669篇 |
1999年 | 805篇 |
1998年 | 692篇 |
1997年 | 623篇 |
1996年 | 553篇 |
1995年 | 458篇 |
1994年 | 354篇 |
1993年 | 263篇 |
1992年 | 196篇 |
1991年 | 157篇 |
1990年 | 116篇 |
1989年 | 100篇 |
1988年 | 80篇 |
1987年 | 51篇 |
1986年 | 50篇 |
1985年 | 24篇 |
1984年 | 23篇 |
1983年 | 16篇 |
1982年 | 18篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
介绍了纳米TiO2复合铁钛防锈颜料的制备原理、工艺、技术指标;描述了铁钛防锈涂料的配方、性能检验和产业化进展情况. 相似文献
22.
Rui-Hong Liang Xian-Lin Dong Ying Chen Fei Cao Yong-Ling Wang 《Journal of the American Ceramic Society》2006,89(10):3273-3276
Ba0.55 Sr0.45 TiO3 /MgO composites were successfully prepared by the heterogeneous precipitation method and their structural, surface morphological, tunable properties, and dielectric properties at microwave frequency were systemically investigated. Compared with the sample prepared by the traditional solid-state method, the sample prepared by the heterogeneous precipitation method exhibits a smaller grain size, more uniform microstructure, higher tunability, and lower microwave loss, and these properties are very beneficial to the development of the microwave tunable devices application. Moreover, the effects of La2 O3 doping on the dielectric and tunable properties of BST/MgO composites are investigated. The result shows that the La3+ -doped sample has higher tunability and lower microwave loss than the undoped one. 相似文献
23.
锌基重防腐双涂层防护技术在高速公路护栏上的应用 总被引:1,自引:0,他引:1
介绍了双涂层防护技术的进展以及锌基重防腐双涂层防护技术在高速公路护栏上的应用。 相似文献
24.
Chunnuan Ji Rongjun Qu Cheng Bo Cao Huo Chen Qiang Xu Changmei Sun Chunhua Wang Huafang Yuan Jun Zhou 《应用聚合物科学杂志》2006,102(6):6054-6059
A novel chelating resin containing sulfoxide and diethylene glycol, poly{4‐vinylbenzyl‐[2‐2‐(hydroxyethyl)ethoxyl]sulfoxide} (PVESO) was synthesized using chloromethylated polystyrene (PS‐Cl) as material. Its structure was characterized by elemental analysis, infrared spectra, and scanning electron microscopy (SEM). The adsorption capacities of the resin for Hg2+, Ag+, Cu2+, Zn2+, and Pb2+ at various pH values were determined. The maximum adsorption capacities for Hg2+ and Ag+ were 1.56 and 0.75 mmol g?1 respectively. The resin had high selectivity for Hg2+ and Ag+ over the pH range 1.0–7.0. The adsorption capacities for Hg2+ and Ag+ under competitive condition were also determined by batch experiment method. In addition, the adsorption kinetics of the resin towards Hg2+ at different temperatures was also investigated. The results showed that the adsorption rate was governed by film diffusion at 20°C and 25°C, by particle diffusion at 30°C and 35°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6054–6059, 2006 相似文献
25.
The PbO2 and F−-doped PbO2 (F-PbO2) film electrodes have been prepared by an electrodeposition process onto platinum substrate. The changes of their electrochemical activity for oxygen evolution (OE) reaction with accelerated electrolysis time have been studied. The results show that the activity of the electrodes decreases with increasing electrolysis time. This can be attributed to the conductivity variations, which are caused by the decrease of the oxygen vacancy concentration in PbO2 films during OE. The mechanism of the decrease of the oxygen vacancies has been investigated. For F-PbO2 film electrodes, though its electrochemical activity is somewhat lower than that of undoped one, its activity stability is much higher in comparison with that of PbO2. The influence of F− doping on the activity of PbO2 film electrodes has been also discussed. 相似文献
26.
农作物秸秆增强氟石膏复合材料的微观结构研究 总被引:1,自引:0,他引:1
将玉米秸秆加入改性后的氟石膏中,研究改性剂、玉米秸秆对氟石膏复合材料结构性能的影响;并用苯丙乳液对玉米秸秆纤维进行表面处理,用以改善基体材料和增强材料的界面结合状况,由此显著提高制品性能。 相似文献
27.
X.Y.?Wang J.M.?WangEmail author H.B.?Shao J.Q.?Zhang C.N.?Cao 《Journal of Applied Electrochemistry》2005,35(2):213-216
The corrosion behavior of pure aluminum in inhibited and uninhibited 4 MKOH was investigated by means of hydrogen collection, polarization curve measurement and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion of pure aluminum was greatly inhibited by the addition of ZnO and dimethyl amine epoxy propane (designated as DE). EIS and EDAX analyses revealed that ZnO produces its effect by depositing on the aluminum surface, which increases the overpotential of hydrogen evolution. It was also found that the addition of DE could greatly improve the deposition of zinc layers. 相似文献
28.
29.
The confined etchant layer technique has been applied to fabricate complex three-dimensional microstructures on nitinol for the first time. HF and HNO3 were locally and simultaneously electrogenerated at the mold surface to etch a nitinol workpiece. NaOH was used as an efficient scavenger to confine the etchant close to the mold. Cyclic voltammetry was employed to study the electrochemical behavior of a Pt electrode in the etching solution in order to choose an appropriate potential for etchant generation on the mold. The thickness of the confined etchant layer was estimated to be several micrometers by inspecting the deviation of the sizes of the etched spots from the sizes of those on the microelectrode. Thus, the composition of the electrolyte could be optimized for better etching precision. By optimizing the composition of the electrolyte, complex microstructures on a Pt-Ir mold bearing the logo “XMU” of Xiamen University were successfully fabricated on nitinol. The etched patterns were approximately negative copies of the mold, and the precision of duplication could easily reach the micrometer scale. 相似文献
30.
To study the effect of the molecular architecture of a copolymer on its miscibility with corresponding homopolymers a series of block copolymers of styrene and isoprene with diblock, triblock and four-arm star architectures have been prepared and the morphologies of the blends of the copolymers and polyisoprene with different molecular weights have been examined by electron microscopy. The results show that miscibility varies in the sequence diblock>triblock>four-arm star copolymers. This sequence is in the opposite direction to the variation of the architectural complexity of the block copolymers, i.e. the more complex is molecular architecture, the greater is conformation restriction in microdomain formation and the less is solubility of homopolymer in corresponding domains. 相似文献