全文获取类型
收费全文 | 14271篇 |
免费 | 445篇 |
国内免费 | 53篇 |
专业分类
电工技术 | 260篇 |
综合类 | 16篇 |
化学工业 | 2271篇 |
金属工艺 | 372篇 |
机械仪表 | 362篇 |
建筑科学 | 219篇 |
矿业工程 | 73篇 |
能源动力 | 703篇 |
轻工业 | 1175篇 |
水利工程 | 190篇 |
石油天然气 | 82篇 |
无线电 | 1614篇 |
一般工业技术 | 2778篇 |
冶金工业 | 3053篇 |
原子能技术 | 198篇 |
自动化技术 | 1403篇 |
出版年
2024年 | 31篇 |
2023年 | 175篇 |
2022年 | 499篇 |
2021年 | 501篇 |
2020年 | 408篇 |
2019年 | 407篇 |
2018年 | 553篇 |
2017年 | 512篇 |
2016年 | 481篇 |
2015年 | 281篇 |
2014年 | 446篇 |
2013年 | 888篇 |
2012年 | 520篇 |
2011年 | 676篇 |
2010年 | 540篇 |
2009年 | 531篇 |
2008年 | 476篇 |
2007年 | 389篇 |
2006年 | 331篇 |
2005年 | 264篇 |
2004年 | 248篇 |
2003年 | 221篇 |
2002年 | 180篇 |
2001年 | 143篇 |
2000年 | 147篇 |
1999年 | 180篇 |
1998年 | 758篇 |
1997年 | 483篇 |
1996年 | 414篇 |
1995年 | 312篇 |
1994年 | 255篇 |
1993年 | 271篇 |
1992年 | 151篇 |
1991年 | 163篇 |
1990年 | 121篇 |
1989年 | 115篇 |
1988年 | 137篇 |
1987年 | 115篇 |
1986年 | 94篇 |
1985年 | 120篇 |
1984年 | 94篇 |
1983年 | 109篇 |
1982年 | 113篇 |
1981年 | 110篇 |
1980年 | 106篇 |
1979年 | 57篇 |
1978年 | 50篇 |
1977年 | 147篇 |
1976年 | 259篇 |
1975年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
151.
152.
This paper describes an algorithm for finding the minimal cutsets between a specified source and terminal nodes of directed/undirected networks. Adjacent nodes of a source node/merged node are determined by the collection of node numbers of columns corresponding to non-zero elements of the first row of the adjacency matrix to form the reduced adjacency matrix (RAM) corresponding to merged nodes. Connectivity of RAM has been checked to obtain the minimal cutsets. 相似文献
153.
Thermal plasma synthesis of SiC from rice hull (husk) 总被引:1,自引:0,他引:1
S. K. Singh L. Stachowicz S. L. Girshick E. Pfender 《Journal of Materials Science Letters》1993,12(9):659-660
154.
V. K. Singh 《Journal of Materials Science》1996,31(19):5163-5168
Measurement of the initial sintering shrinkage of CaAl2O4 at temperatures of 1300, 1325 and 1350 °C are reported. The particle sizes chosen were –53 + 45, –63 + 53 and –75 + 63 microns and the soaking periods were from 15 to 360 min. A time dependence of the shrinkage has shown that volume diffusion is the dominant mechanism of sintering. At any given time and temperature, the per cent shrinkage was found to be a decreasing function of particle size. The activation energy for the sintering of CaAl2O4 was found to be 766.38 KJ mol–1. 相似文献
155.
156.
157.
158.
Evaluation of rainfall networks using entropy: II. Application 总被引:2,自引:0,他引:2
This paper, the second in the series, applies the entropy approach to space and time evaluation of rainfall networks in Louisiana. The evaluation is made for five sampling intervals: daily, 2-day, weekly, monthly, and yearly, and for two separate seasons. In each case, the best combination of raingages is suggested and the lines of equal information (isoinformation contours) are constructed showing the areas of greater or less information transfer. The isoinformation lines are especially suitable in decisions concerning the expansion of the existing network or deleting the unnecessary raingages. 相似文献
159.
An earlier neural network analysis of processing of steel plates through hot rolling was subjected to a further refined analysis through some flexible neural networks that evolved using a multi‐objective predator‐prey genetic algorithm. The original data set expressing the Yield Strength and Ultimate Tensile Strength of the rolled slabs in terms of a total of 108 process variables were subjected to a systematic pruning through this evolutionary approach, till the nitrogen content of the steel emerged as the most significant input variable. A theoretical explanation is provided for this slightly unexpected result. 相似文献
160.
In the present paper, a modified self-flux technique has been successfully employed for the growth of pure and praseodymium
substituted (partially) large single crystals of high temperature superconducting Y1−x
Pr
x
Ba2Cu3O7−δ
(x = 0·0,0·2,0·4). Typical sizes of the platy and bulky crystals of pure YBCO(123) material are ≈ 2 × 2 × 0·1 mm3 and 4 × 1 × 1 mm3, respectively. In case of Pr-substitution, the typical sizes of platy and bulky crystals of Y0·8Pr0·2Ba2Cu3O7−δ
and Y0·6Pr0·4Ba2Cu3O7−δ
materials are ≈ 2 × 3 × 0·1 mm3 and 5 × 1 × 1 mm3 and ≈ 1 × 1·5 × 0·1 mm3 and 7 × 0·2 × 0·1 mm3, respectively. The morphology and growth habit of the as-grown single crystals and the critical transition temperature (T
c) of the oxygenated crystals were found to depend on the Pr-content.
Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995 相似文献