全文获取类型
收费全文 | 35421篇 |
免费 | 2892篇 |
国内免费 | 963篇 |
专业分类
电工技术 | 1357篇 |
综合类 | 1042篇 |
化学工业 | 6955篇 |
金属工艺 | 2004篇 |
机械仪表 | 2324篇 |
建筑科学 | 1567篇 |
矿业工程 | 618篇 |
能源动力 | 1282篇 |
轻工业 | 2788篇 |
水利工程 | 356篇 |
石油天然气 | 992篇 |
武器工业 | 115篇 |
无线电 | 4816篇 |
一般工业技术 | 6211篇 |
冶金工业 | 2738篇 |
原子能技术 | 367篇 |
自动化技术 | 3744篇 |
出版年
2024年 | 125篇 |
2023年 | 561篇 |
2022年 | 956篇 |
2021年 | 1408篇 |
2020年 | 1049篇 |
2019年 | 982篇 |
2018年 | 1145篇 |
2017年 | 1163篇 |
2016年 | 1254篇 |
2015年 | 1294篇 |
2014年 | 1678篇 |
2013年 | 2236篇 |
2012年 | 2206篇 |
2011年 | 2580篇 |
2010年 | 2091篇 |
2009年 | 2050篇 |
2008年 | 1878篇 |
2007年 | 1523篇 |
2006年 | 1417篇 |
2005年 | 1250篇 |
2004年 | 1025篇 |
2003年 | 1007篇 |
2002年 | 902篇 |
2001年 | 761篇 |
2000年 | 701篇 |
1999年 | 738篇 |
1998年 | 979篇 |
1997年 | 725篇 |
1996年 | 557篇 |
1995年 | 439篇 |
1994年 | 391篇 |
1993年 | 319篇 |
1992年 | 231篇 |
1991年 | 180篇 |
1990年 | 173篇 |
1989年 | 161篇 |
1988年 | 115篇 |
1987年 | 89篇 |
1986年 | 94篇 |
1985年 | 103篇 |
1984年 | 91篇 |
1983年 | 58篇 |
1982年 | 51篇 |
1981年 | 57篇 |
1980年 | 55篇 |
1979年 | 44篇 |
1978年 | 39篇 |
1977年 | 58篇 |
1976年 | 91篇 |
1975年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 27 毫秒
51.
52.
53.
Kazutaka Chibana Chaedong Kang Masashi Okada Koji Matsumoto Tetsuo Kawagoe 《International Journal of Refrigeration》2002,25(2):83
Water-silicone oil emulsion with an additive, (C2H5O)3SiC3H6NH2, was examined as a heat storage material. A spiral tube used as a heat exchanger was immersed in a low temperature bath and the emulsion was circulated in the tube to make ice continuously. Ice was separated from the ice–liquid suspension in an outlet tank. The amount of formed ice, the temperatures of the inlet and the outlet of the heat exchanger, and the temperatures in the tube wall were measured and the overall heat transfer coefficient and the heat flux through the tube were calculated. Experiments were carried out, varying the flow rate, the temperature of cooling brine, and the thickness of tube wall. The condition under which slurry ice was formed continuously without adhesion of ice to the cooling wall was clarified. Though decrease in the thermal resistance of the tube increased the rate of ice formation or raised the brine temperature, it narrowed the range of the flow rate and of the brine temperature in which slurry ice was formed continuously. 相似文献
54.
55.
56.
Kyung-Won Lee Eung Soo Kim Hee Cheon No Chul-Hwa Song 《Nuclear Engineering and Design》2006,236(9):1003-1012
We experimentally investigate the de-entrainment of droplets by inertial impaction on an array of vertical rods in an air-droplet mixture flow. The de-entrainment efficiencies are measured for a single rod, for a single row of rods, and for a multi-row of rods. We investigate the effects of the droplet mass flux (0.5–5.4 kg/m2 s), the droplet Weber number (3000–8000), the air velocity (0–6 m/s), the rod geometry, and the surface roughness on the de-entrainment, and the rod diameter-to-pitch ratio effect on the de-entrainment. The results for a single rod show that the de-entrainment efficiency decreases slightly as the droplet mass flux increases; however, in our experimental ranges, there is negligible dependence on the droplet Weber number, the air velocity, and the surface roughness. The rod geometry affects the de-entrainment efficiency. The results for a single row of rods show that the existence of neighboring rods promotes de-entrainment due to droplet splashing, and we develop a correlation to show the effect of diameter-to-pitch ratio on the de-entrainment. Using information on the de-entrainment efficiencies of a single rod and those of a single row of rods, we propose a correlation that predicts the de-entrainment efficiency for a multi-row of rods with a staggered array. The RMS errors of the correlation from the de-entrainment efficiencies experimentally obtained are within 13.5%. 相似文献
57.
58.
掺杂对低压ZnO压敏陶瓷材料显微结构及性能的影响 总被引:1,自引:0,他引:1
本文探讨了多种金属氧化物对ZnO-Bi_2O_3-TiO_2系材料的改性作用和对其微结构的影响,为得到预定性能的材料提供了掺杂方面的实验依据。 相似文献
59.
Keon Woo Kang Jaemin Ann Hwang Soo Lee 《Electronics letters》1994,30(25):2153-2154
The authors propose a method to estimate the synchronisation offset for orthogonal frequency division multiplexing (OFDM) frame alignment without resort to pilot tones. A decision-directed maximum-likelihood estimation of frame synchronisation offset is derived, and the performance of the proposed scheme is confirmed by computer simulation for QAM systems 相似文献
60.
钒冶炼焙烧添加剂选择研究 总被引:1,自引:0,他引:1
对小型钒冶炼厂焙烧工艺所用添加剂进行改进的可能性进行了探讨,研究了几种常用添加剂的焙烧条件,分析比较了其性能,提出用NaCl-Na2CO3作焙烧添加剂替代NaCl可大幅度减少大气污染,提高冶钒转化率;且不改变工艺流程,无需设备投资,具有较好的经济效益和环境效益。 相似文献