全文获取类型
收费全文 | 7370篇 |
免费 | 771篇 |
国内免费 | 320篇 |
专业分类
电工技术 | 161篇 |
综合类 | 540篇 |
化学工业 | 2311篇 |
金属工艺 | 290篇 |
机械仪表 | 193篇 |
建筑科学 | 299篇 |
矿业工程 | 165篇 |
能源动力 | 195篇 |
轻工业 | 310篇 |
水利工程 | 165篇 |
石油天然气 | 348篇 |
武器工业 | 167篇 |
无线电 | 1525篇 |
一般工业技术 | 1262篇 |
冶金工业 | 160篇 |
原子能技术 | 140篇 |
自动化技术 | 230篇 |
出版年
2025年 | 1篇 |
2024年 | 99篇 |
2023年 | 98篇 |
2022年 | 142篇 |
2021年 | 173篇 |
2020年 | 236篇 |
2019年 | 191篇 |
2018年 | 168篇 |
2017年 | 238篇 |
2016年 | 227篇 |
2015年 | 267篇 |
2014年 | 375篇 |
2013年 | 539篇 |
2012年 | 462篇 |
2011年 | 477篇 |
2010年 | 397篇 |
2009年 | 399篇 |
2008年 | 348篇 |
2007年 | 469篇 |
2006年 | 461篇 |
2005年 | 411篇 |
2004年 | 383篇 |
2003年 | 305篇 |
2002年 | 292篇 |
2001年 | 218篇 |
2000年 | 181篇 |
1999年 | 148篇 |
1998年 | 126篇 |
1997年 | 94篇 |
1996年 | 89篇 |
1995年 | 81篇 |
1994年 | 75篇 |
1993年 | 62篇 |
1992年 | 48篇 |
1991年 | 36篇 |
1990年 | 32篇 |
1989年 | 33篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1975年 | 2篇 |
1959年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有8461条查询结果,搜索用时 9 毫秒
1.
Xue‐Yong Liu Xiao‐Bin Ding Zhao‐Hui Zheng Yu‐Xing Peng Albert S
C Chan C
W Yip Xin‐Ping Long 《Polymer International》2003,52(2):235-240
Amphiphilic magnetic microspheres ranging in diameter from 5 to 100 µm were prepared by dispersion copolymerization of styrene and poly(ethylene oxide) vinylbenzyl (PEO‐VB) macromonomer (MPEO) in the presence of Fe3O4 magnetic fluid. The effects of various polymerization parameters on the average particle size were systematically investigated. The average particle size was found to increase with increasing styrene concentration and initiator concentration. It also increased with decreasing stabilizer concentration and molecular weight of MPEO. The content of the hydroxyl groups localized in the microspheres ranged from 0.01 to 0.2 mmol g?1. © 2003 Society of Chemical Industry 相似文献
2.
Yilmaz Muslu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1991,51(4):449-460
A dispersed flow model previously developed to study substrate utilization in unsaturated media was experimentally verified and its practical application was considered. For this purpose, measurements were made using tap water and a synthetic feed solution. The importance of the change in fluid regime as regards to the simultaneous transport and reaction within biological filters were demonstrated. The effect of drop formation and the breakage of liquid jets inside the filters on substrate utilization was also shown. 相似文献
3.
Aggregates of carbon black (CB) in a polymer matrix have a tendency to form a CB network. The dynamic mechanical properties of binary systems of chlorinated polyethylene (CPE) and CB or 3,9‐bis{1,1‐dimethyl‐2[β‐(3‐tert‐butyl‐4‐hydroxy‐5‐methylphenyl)propionyloxy]ethyl}‐2,4,8,10‐tetraoxaspiro[5,5]‐undecane (AO‐80) and their ternary systems were investigated. It was found that the dynamic mechanical properties of those systems depend on the colloidal properties, surface oxides, and surface modification of CB. For binary systems of CPE and CB, oxidized CB gives a high modulus at low strain amplitude and a large Payne effect compared with untreated CB. In contrast, the reverse effect was observed for their ternary systems. Consequently, a good micro‐dispersion is obtainable by surface modification due to physical adsorption of AO‐80 on oxidized CB particles via hydrogen bonds. © 2003 Society of Chemical Industry 相似文献
4.
Osasere Faraday F. Orumwense 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1994,60(4):405-411
Dispersion–flocculation studies on a Goethite–clay system using flocculants were carried out as a function of flocculant concentrations, pH of slurry, time of agitation and dispersant dosage. Also, the effects of pH and polymer concentrations on the adsorption behaviour of the system were investigated. Results show that well flocculated goethite was preferentially obtained from 4% goethite/kaolinite clay suspensions, with 50 ppm causticised starch in the slurry at pH values of 3–11·5 and with 50 ppm polyacrylamide at pH values of 3–8. Good flocs were also obtained on flocculation of the goethite suspension with 50 ppm polyacrylamide at pH values of 5–7, while the kaolinite suspension did not respond to the same dosage of causticised starch in the same pH range. Results further reveal that for the goethite/kaolinite suspension, the best results was obtained with 50 ppm polyacrylamide at pH values of 7–10. Based on the data generated in the study, it was concluded that causticised starch is a better flocculant than polyacrylamide for goethite suspensions although polyacrylamide is an excellent flocculant for kaolinite suspensions. 相似文献
5.
6.
M. Rahman 《化学,工程师,技术》1975,47(17):729-729
7.
Microstructure and mechanical properties of Al2O3/TiAl composite 总被引:4,自引:1,他引:4
8.
为研究高能超声处理制备纳米复合材料过程中纳米增强相在熔体中的分散过程,采用甘油为介质分别进行了数值模拟以及物理模拟。数值模拟结果表明,当超声作用于甘油中时,甘油中会形成中心-底面-壁面-中心的环形流动,变幅杆探头端面边缘附近甘油流体存在最大的流动速度,且随着超声功率的增大,流体运动速度增大。物理模拟实验结果显示,高能超声作用下甘油的实际运动行为与数值模拟结果相符合,存在环形流动;此外,高能超声作用下甘油中存在明显的空化效应;纳米晶须在超声作用下于甘油中分散良好,且随着超声功率的增大,达到充分分散所需时间变短。 相似文献
9.
E. Van Groesen 《Journal of Engineering Mathematics》1998,34(1-2):215-226
Uni-directional wave models are used to study wave groups that appear in wave tanks of hydrodynamic laboratories; characteristic for waves in such tanks is that the wave length is rather small, comparable to the depth of the layer. In second-order theory, the resulting Nonlinear Schrödinger (NLS) equation for the envelope of the wave group contains the dispersion of the group velocity multiplying the linear term and a gen-coefficient that results from mode generation multiplying the nonlinear term. The signs of these coefficients determine whether experimentally relevant wave groups are possible or not. If the dispersion is modelled in such a way that it is correct for all wave lengths for infinitesimal waves, relevant wave groups are obtained consisting of constituent waves with a certain maximal wave length; other models for the dispersion (such as in the KdV-equation) lead to different results. 相似文献
10.
文献的语言风格是作者在语言运用方面的思维定势的体现,对于文献之间语言风格的差异,以前的研究大多采用定性分析的方式加以比较和概括,而在文献检索和文本分类领域需要得到量化的语言风格相似度。该文首先分析文献中词语分布的普遍规律,以先秦八部经典文献为观察语料,发现这些文献中的词语既呈离散分布,又呈集中分布;然后通过计算文献之间词型等级的相关系数,来获取量化的语言风格相似度,构建了八部文献之间的相似度矩阵,验证了语言风格的差异不仅体现在使用的常用词上,还更细微地体现在常用词的使用频率等级上。 相似文献