全文获取类型
收费全文 | 5823篇 |
免费 | 571篇 |
国内免费 | 219篇 |
专业分类
电工技术 | 28篇 |
综合类 | 371篇 |
化学工业 | 3159篇 |
金属工艺 | 73篇 |
机械仪表 | 57篇 |
建筑科学 | 35篇 |
矿业工程 | 62篇 |
能源动力 | 179篇 |
轻工业 | 709篇 |
水利工程 | 3篇 |
石油天然气 | 1142篇 |
武器工业 | 2篇 |
无线电 | 31篇 |
一般工业技术 | 169篇 |
冶金工业 | 174篇 |
原子能技术 | 57篇 |
自动化技术 | 362篇 |
出版年
2024年 | 19篇 |
2023年 | 68篇 |
2022年 | 158篇 |
2021年 | 150篇 |
2020年 | 146篇 |
2019年 | 128篇 |
2018年 | 123篇 |
2017年 | 128篇 |
2016年 | 156篇 |
2015年 | 202篇 |
2014年 | 379篇 |
2013年 | 383篇 |
2012年 | 470篇 |
2011年 | 442篇 |
2010年 | 326篇 |
2009年 | 271篇 |
2008年 | 240篇 |
2007年 | 325篇 |
2006年 | 320篇 |
2005年 | 299篇 |
2004年 | 309篇 |
2003年 | 275篇 |
2002年 | 223篇 |
2001年 | 193篇 |
2000年 | 177篇 |
1999年 | 135篇 |
1998年 | 116篇 |
1997年 | 82篇 |
1996年 | 70篇 |
1995年 | 73篇 |
1994年 | 48篇 |
1993年 | 38篇 |
1992年 | 32篇 |
1991年 | 29篇 |
1990年 | 18篇 |
1989年 | 18篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1982年 | 6篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1951年 | 5篇 |
排序方式: 共有6613条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
甲缩醛反应精馏过程模拟 总被引:4,自引:0,他引:4
通过实验取得了甲醛和甲醇合成甲缩醛的反应参数;建立了其连续生产工艺的数学模型,利用ASPEN PLUS软件对甲醛和甲醇缩合生成甲缩醛进行了模拟,结果表明反应精馏连续生产甲缩醛的工艺是可行的,转化率高达99%,并得到含甲缩醛99%的产物,同时确定了进料板和反应区. 相似文献
86.
Javier Viguri Raquel Onandí a Roberto Arce Angel Irabien 《Chemical Engineering Communications》2005,192(11):1490-1504
In the present study the characterization and distillation of alkyd paint waste have been carried out in order to establish the technical viability of organic solvents recovery and to decide upon the best environmental management for the waste stream from a paint spray-booth application in an automotive component factory. The paint is a black primer based on an alkyd resin with toluene and xylene as solvents, black carbon as pigment, fillers, and other minor components.
The paint, paint wastes, and distillation wastes have been characterized by determination of the physicochemical properties of the solid (solvents content and flash point) and determination of ecotoxicity (EC50), total organic carbon (TOC), and metals concentration of the leachates. The highly volatile matter (HVM) content, determined by the weight loss at 200°C, has been used as a parameter to relate with the hazardous wastes regulations based on the characterization parameters EC50, TOC, and flash point.
Distillation experiments have been performed in a simple batch mode with mixtures of paint waste, water, and additives in order to obtain high efficiencies in the recovery of volatile organic compounds and to obtain a final solid with nonhazardous behavior and good manageability qualities. A fractional factorial design (23-1) of experiments was carried out in order to study the influence of the distillation variables: water/paint waste ratio (2/1-3/1 (g/g)), temperature (110°-145°C), alkaline additives (Na(OH),CaO, Ca(OH)2), and amount of other additives (wt.% of bentonite, cement, and Ca(OH)2) on the solvent recovery, [% VOCs]Recovery, on the residual volatile organic compounds, [% VOCs]Distillation Waste, and on the total organic content (TOC) of the waste leachates. The present work shows the quantitative results of the alkyd paint waste distillation process under optimum conditions. 相似文献
The paint, paint wastes, and distillation wastes have been characterized by determination of the physicochemical properties of the solid (solvents content and flash point) and determination of ecotoxicity (EC50), total organic carbon (TOC), and metals concentration of the leachates. The highly volatile matter (HVM) content, determined by the weight loss at 200°C, has been used as a parameter to relate with the hazardous wastes regulations based on the characterization parameters EC50, TOC, and flash point.
Distillation experiments have been performed in a simple batch mode with mixtures of paint waste, water, and additives in order to obtain high efficiencies in the recovery of volatile organic compounds and to obtain a final solid with nonhazardous behavior and good manageability qualities. A fractional factorial design (23-1) of experiments was carried out in order to study the influence of the distillation variables: water/paint waste ratio (2/1-3/1 (g/g)), temperature (110°-145°C), alkaline additives (Na(OH),CaO, Ca(OH)2), and amount of other additives (wt.% of bentonite, cement, and Ca(OH)2) on the solvent recovery, [% VOCs]Recovery, on the residual volatile organic compounds, [% VOCs]Distillation Waste, and on the total organic content (TOC) of the waste leachates. The present work shows the quantitative results of the alkyd paint waste distillation process under optimum conditions. 相似文献
87.
In a previous study on the basis of reaction equilibrium, it was demonstrated that the synthesis of fatty acids esters of heavy alcohols by catalytic reactive distillation (RD) is basically feasible. Presently, the analysis is expanded to the kinetics-based design applied to the synthesis of 2-ethylhexyl dodecanoate. Experimental data for a super-acidic sulphated zirconia catalyst are employed. It is shown that this catalyst is highly selective even for the high alcohol/acid ratios as prevail in a RD column. To avoid catalyst deactivation, liquid-liquid segregation into an organic and an aqueous phase must be prevented, and operating temperatures beyond must be chosen. A kinetic model based on liquid activities is proposed, with parameters determined from both kinetic and equilibrium measurements. A typical column design has 13 reactive stages with a catalyst loading of , temperature profile of 400-, and a space velocity of for 99.9% purity product ester. A modified Damköhler number is proposed. 相似文献
88.
反应精馏过程模拟研究进展 总被引:16,自引:0,他引:16
对均相反应精馏和非均相催化精馏过程的各种模拟计算方法进行了评述,分析了各种算法的优缺点和适用范围,指明了目前研究中存在的不足和今后的发展方向。 相似文献
89.
90.