全文获取类型
收费全文 | 15365篇 |
免费 | 1317篇 |
国内免费 | 610篇 |
专业分类
电工技术 | 854篇 |
技术理论 | 2篇 |
综合类 | 855篇 |
化学工业 | 2693篇 |
金属工艺 | 965篇 |
机械仪表 | 965篇 |
建筑科学 | 1156篇 |
矿业工程 | 519篇 |
能源动力 | 439篇 |
轻工业 | 908篇 |
水利工程 | 250篇 |
石油天然气 | 1221篇 |
武器工业 | 104篇 |
无线电 | 1688篇 |
一般工业技术 | 1942篇 |
冶金工业 | 836篇 |
原子能技术 | 149篇 |
自动化技术 | 1746篇 |
出版年
2024年 | 80篇 |
2023年 | 309篇 |
2022年 | 476篇 |
2021年 | 672篇 |
2020年 | 536篇 |
2019年 | 452篇 |
2018年 | 520篇 |
2017年 | 519篇 |
2016年 | 458篇 |
2015年 | 603篇 |
2014年 | 782篇 |
2013年 | 844篇 |
2012年 | 942篇 |
2011年 | 995篇 |
2010年 | 877篇 |
2009年 | 859篇 |
2008年 | 882篇 |
2007年 | 764篇 |
2006年 | 787篇 |
2005年 | 656篇 |
2004年 | 528篇 |
2003年 | 444篇 |
2002年 | 432篇 |
2001年 | 363篇 |
2000年 | 350篇 |
1999年 | 413篇 |
1998年 | 298篇 |
1997年 | 280篇 |
1996年 | 241篇 |
1995年 | 218篇 |
1994年 | 174篇 |
1993年 | 126篇 |
1992年 | 109篇 |
1991年 | 68篇 |
1990年 | 66篇 |
1989年 | 46篇 |
1988年 | 29篇 |
1987年 | 26篇 |
1986年 | 15篇 |
1985年 | 13篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
In this research, Ni/SiO2 catalyst was modified with different amount of Gd2O3 and characterized with temperature-programmed desorption of CO2 (CO2-TPD) and NH3 (NH3-TPD), temperature-programmed reduction with H2 (H2-TPR) and X-ray diffraction (XRD). It was found that Gd2O3-modified Ni/SiO2 catalysts possessed higher CO2 adsorption and activation ability due to the formation of surface carbonate species. H2-TPR and XRD characterizations found that the strong interaction among nickel, Gd2O3 and SiO2 took place, which improved the dispersion of Ni. Gd2O3-modified Ni/SiO2 catalysts exhibited higher activity and stability for the combined oxy-CO2 reforming of methane in fluidized-bed reactor. The H2/CO ratio in produced syngas could be controlled via controlling reaction temperature and CO2/O2 ratio in feed. 相似文献
42.
Hsu‐Wei Fang Hsien‐Chieh Wang Teh‐Hua Tsai Wei‐Bor Tsai Shao‐Yi Hou Hsuan‐Liang Liu Wun‐Hsing Lee Yung‐Chang Lu Chun‐Hsiung Huang 《应用聚合物科学杂志》2008,108(4):2428-2437
Wear of ultrahigh‐molecular‐weight polyethylene (UHMWPE) and wear‐particle‐induced osteolysis and bone resorption are the major factors causing the failure of total joint replacements. It is feasible to improve the lubrication and reduce the wear of artificial joints. We need further understanding of the lubrication mechanism of the synovial fluid. The objective of this study is to evaluate the lubricating ability of three major components in the synovial fluid: albumin, globulin, and phospholipids. An accelerated wear testing procedure in which UHMWPE is rubbed against a microfabricated surface with controlled asperities has been developed to evaluate the lubrication behavior. An analysis of the wear particle dimensions and wear amount of the tests has provided insights for comparing their lubrication performance. It is concluded that the presence of biomolecules at the articulating interface may reduce friction. A higher concentration of a biological lubricant leads to a decrease in the wear particle width. In addition, in combination with the wear results and mechanical analysis, the roles of individual biomolecules contributing to friction and wear at the articulating interface are discussed. These results can help us to identify the role of the biomolecules in the boundary lubrication of artificial joints, and further development of lubricating additives for artificial joints may be feasible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
43.
本文简要介绍深圳某商住楼通风空调系统、水系统的设计及空调方式的选取、简述了各项设计的技术数据,可供同行参考。 相似文献
44.
The self-assembly of various nanostructures is recently attracting a great deal of research attention. In this paper, we demonstrate that a palladium chloride aqueous solution, mixed with a proper ammonia solution, can produce Tetra-amminepalladous chloride (Pd(NH3)4Cl2·H2O) nanowires. These nanowires can spontaneously form the two-dimensional hexagon-oriented Pd(NH3)4Cl2·H2O arrays on mica surfaces. We can control the length and height of these nanowires by adjusting their deposit time on the mica substrate. This method can be potentially used in making sensors or in making templates to wire and position nanodevices. 相似文献
45.
HouDianguo 《中国炼油与石油化工》2003,(2):51-56
Reduction of sulfur content in FCC gasoline was studied in a fixed fluid bed (FFB) unit by using metal-modified LV-23 FCC catalyst. The results showed that the sulfur content in FCC gasoline could be reduced with LV-23 catalyst modified with zinc, palladium, zinc-palladium, zinc-cobalt, and zinc-nickel. Among these metals or metal combinations, palladium-containing catalyst was the most effective. Desulfufization of the heavy fraction of FCC gasoline was more effective than full-range gasoline under the same conditions with palladium-containing catalysts. A high reaction temperature was favorable to desulfurization, but it would reduce the yield of liquid product. After desulfurization reaction, the olefm content of product gasoline decreased while the aromatic and iso-alkane contents increased. Removal of thiophene and benzothiophene is higher. 相似文献
46.
47.
We report the first demonstration of proton-exchanged optical planar waveguides in x-cut and z-cut LiNbO3 doped with 6 mol% ZnO using adipic acid as proton source. These waveguides exhibit a graded index profile which can be modeled by a linear step function with a surface index increase of 0.135 and 0.14 for x-cut and z-cut waveguides, respectively. The diffusion constant Do and the activation energy Q are characterized optically to be 1.64×109 μm2/h and 88.8 KJ/mol for x-cut waveguides, and 1.478×109 μm2/h and 91.25 KJ/mol for z-cut waveguides, respectively. The diffusion rate along the z-axis is slower than that along the x-axis, whereas the surface index increase on z-cut waveguides is larger than that on x-cut waveguides. 相似文献
48.
从烧结矿冷却并回收其余热的角度出发,介绍了利用烧结机尾落矿空间,采用喷吹空气装置对烧结矿进行冷却的小型模拟试验,从测出的结果来看,有可能成为一种新的烧结矿冷却方式。 相似文献
49.
本文阐述了一项水能利用的新技术:通过密闭容器将水的落差转换成压力气体,再通过压力气体去压缩另一密闭容器内的水。进而实现提水的目的。实验、计算和分析显示,这是一种切实可行的提水新技术。 相似文献
50.
工程征地移民监测评价在万家寨引黄工程中的应用 总被引:1,自引:0,他引:1
万家寨引黄工程是世界银行(以下简称“世行”)贷款项目,《万家寨引黄工程总干线、南干线及联接段工程征地移民规划报告》于1996年10月世行政在式评估通过确认按世行移民导则要求独立的外部监督机构,对引黄工程征民移民规划实施进行监测评价,为此,山西省万家寨引黄工程总公司委托黄河水利委员会移民局担任此项工作,并得到了世行的认可,监测评价的目的是确保工程征地移民安置规划的实施,严格按照国家的有关法规、政策及世行4.30导则要求,监测评价工作从1997-2001年每年监测2次,并提交2次独立的监测评价报告,到目前已实施了4年。 相似文献