全文获取类型
收费全文 | 64994篇 |
免费 | 5717篇 |
国内免费 | 2868篇 |
专业分类
电工技术 | 3561篇 |
技术理论 | 2篇 |
综合类 | 4108篇 |
化学工业 | 10696篇 |
金属工艺 | 3713篇 |
机械仪表 | 4063篇 |
建筑科学 | 4689篇 |
矿业工程 | 2137篇 |
能源动力 | 1693篇 |
轻工业 | 3998篇 |
水利工程 | 1070篇 |
石油天然气 | 3919篇 |
武器工业 | 524篇 |
无线电 | 7690篇 |
一般工业技术 | 7750篇 |
冶金工业 | 4490篇 |
原子能技术 | 634篇 |
自动化技术 | 8842篇 |
出版年
2024年 | 353篇 |
2023年 | 1132篇 |
2022年 | 1830篇 |
2021年 | 2573篇 |
2020年 | 1973篇 |
2019年 | 1765篇 |
2018年 | 1922篇 |
2017年 | 2115篇 |
2016年 | 1917篇 |
2015年 | 2476篇 |
2014年 | 3019篇 |
2013年 | 3623篇 |
2012年 | 4050篇 |
2011年 | 4448篇 |
2010年 | 3675篇 |
2009年 | 3514篇 |
2008年 | 3388篇 |
2007年 | 3290篇 |
2006年 | 3656篇 |
2005年 | 3030篇 |
2004年 | 2119篇 |
2003年 | 1800篇 |
2002年 | 1590篇 |
2001年 | 1443篇 |
2000年 | 1556篇 |
1999年 | 1752篇 |
1998年 | 2008篇 |
1997年 | 1515篇 |
1996年 | 1313篇 |
1995年 | 1055篇 |
1994年 | 899篇 |
1993年 | 643篇 |
1992年 | 434篇 |
1991年 | 380篇 |
1990年 | 272篇 |
1989年 | 230篇 |
1988年 | 194篇 |
1987年 | 130篇 |
1986年 | 110篇 |
1985年 | 73篇 |
1984年 | 30篇 |
1983年 | 23篇 |
1982年 | 37篇 |
1981年 | 24篇 |
1980年 | 33篇 |
1979年 | 10篇 |
1978年 | 13篇 |
1977年 | 41篇 |
1976年 | 68篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
On structural and high temperature electrochemical properties of ZrO2 thin film coating on Zr metal produced by carbonate melt 总被引:1,自引:0,他引:1
Melt of NaCO3 can favor oxidation of Zr to form ZrO2 thin film on Zr surface, which is used to make Zr/ZrO2 oxidation/reduction electrode of pH sensor for testing elevated temperature aqueous solutions. Using SEM, EPMA, XPS, EXAFS
and HRTEM, we found that ZrO2 film is tightness and solid with 20 μm thickness composed by nanometer-sized monoclinic crystals. Zr/ZrO2 interface is characterized of zoning structure according to topography and chemical composition in five zones: oxygen-rich
ZrO2, ZrO2, oxygen-rich Zr metal, oxygen-bearing Zr and Zr from outmost to center. Melt oxidation process of Zr involved oxidation time,
air and temperature. The air is important effect on structural and electrochemical properties of ZrO2 thin film for making elevate temperature electrochemical sensor. If oxygen air largely presented in carbonate melting process,
ZrO2 thin film is not tightness and not for oxidation/reduction electrode. 相似文献
73.
The thick film of Zn-Sb-O was prepared by coating the paste of nanoparticles mixture (Sb2O3:ZnO=1:3) on the alumina substrate, followed by sintering at 500-900 °C for 2 h in air. The electrical resistance and gas-sensing properties to benzene, alcohol and acetone of Zn-Sb-O films were found to be dependent on the change of phase structure caused by sintering temperature. 相似文献
74.
76.
从实际出发 探索办学理念 总被引:1,自引:0,他引:1
胡伟清 《重庆科技学院学报(社会科学版)》2008,(11)
从学生、社会、学校、教师和学科诸多方面探索办学理念.提出通过学科、专业、课程、教学方法、考核方式等的改革,培养工商企业所需的有较高素质和发展潜力的人才. 相似文献
77.
Local residence time,residence revolution,and residence volume distributions in twin‐screw extruders
Xian‐Ming Zhang Lian‐Fang Feng Sandrine Hoppe Guo‐Hua Hu 《Polymer Engineering and Science》2008,48(1):19-28
This work was aimed at studying the overall, partial, and local residence time distributions (RTD); overall, partial and local residence revolution distributions (RRD) and overall, partial and local residence volume distributions (RVD) in a co‐rotating twin screw extruder, on the one hand; and establishing the relationships among them, on the other hand. Emphasis was placed on the effects of the type and geometry of mixing elements (a gear block and various types of kneading elements differing in staggering angle) and process parameters on the RTD, RRD and RVD. The overall and partial RTD were directly measured in‐line during the extrusion process and the local ones were calculated by deconvolution based on a statistical theory. The local RTD allowed comparing the mixing performance of mixing elements. Also it was confirmed both experimentally and theoretically that specific throughput, defined as a ratio of throughput (Q) over screw speed (N), controlled all the above three types of residence distributions, be they local, partial or overall. The RRD and RVD do not provide more information on an extrusion process than the corresponding RTD. Rather they are different ways of representing the same phenomena. POLYM. ENG. SCI., 48:19–28, 2008. © 2007 Society of Plastics Engineers 相似文献
78.
80.
Zhenghong Yang Yongjian Hu 《Automatic Control, IEEE Transactions on》2004,49(10):1783-1792
In this note, a generalized Bezoutian matrix with respect to a polynomial sequence of interpolatory type is introduced. The operator representation relative to a pair of dual bases and the generalized Barnett-type factorization formula are derived. An intertwining relation and a Bezoutian reduction to a block diagonal form by congruence via a generalized Vandermonde matrix are presented. Fujiwara-Hermite and Routh-Hurwitz criteria in terms of this generalized Bezout matrix are obtained. 相似文献