全文获取类型
收费全文 | 26444篇 |
免费 | 1792篇 |
国内免费 | 462篇 |
专业分类
电工技术 | 428篇 |
综合类 | 1088篇 |
化学工业 | 14463篇 |
金属工艺 | 677篇 |
机械仪表 | 347篇 |
建筑科学 | 627篇 |
矿业工程 | 268篇 |
能源动力 | 216篇 |
轻工业 | 6316篇 |
水利工程 | 82篇 |
石油天然气 | 833篇 |
武器工业 | 41篇 |
无线电 | 242篇 |
一般工业技术 | 2416篇 |
冶金工业 | 381篇 |
原子能技术 | 210篇 |
自动化技术 | 63篇 |
出版年
2024年 | 111篇 |
2023年 | 248篇 |
2022年 | 560篇 |
2021年 | 657篇 |
2020年 | 641篇 |
2019年 | 576篇 |
2018年 | 573篇 |
2017年 | 714篇 |
2016年 | 831篇 |
2015年 | 901篇 |
2014年 | 1156篇 |
2013年 | 1609篇 |
2012年 | 1911篇 |
2011年 | 1781篇 |
2010年 | 1339篇 |
2009年 | 1455篇 |
2008年 | 1284篇 |
2007年 | 1620篇 |
2006年 | 1616篇 |
2005年 | 1250篇 |
2004年 | 1082篇 |
2003年 | 1022篇 |
2002年 | 882篇 |
2001年 | 741篇 |
2000年 | 738篇 |
1999年 | 627篇 |
1998年 | 561篇 |
1997年 | 349篇 |
1996年 | 348篇 |
1995年 | 293篇 |
1994年 | 241篇 |
1993年 | 212篇 |
1992年 | 214篇 |
1991年 | 142篇 |
1990年 | 88篇 |
1989年 | 65篇 |
1988年 | 35篇 |
1987年 | 44篇 |
1986年 | 42篇 |
1985年 | 37篇 |
1984年 | 28篇 |
1983年 | 18篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 13篇 |
1978年 | 6篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
33.
Animesh Chakrabarti Man Mohan Sharma 《Journal of the American Oil Chemists' Society》1992,69(12):1251-1253
Anhydrous esterification of myristic acid with propylene was carried out in the temperature range of 110–145°C and pressure
from 190–195 psig in the presence of Amberlyst-15 (cation exchange resin) and Filtrol-24 (acid-treated clay) as catalysts.
The product ester, isopropyl myristate finds use in cosmetic and topical medicinal preparations where good absorption through
the skin is desired. Filtrol-24 is the catalyst of choice, and the recommended operating temperature is 130°C with a pressure
of 190 psig. 相似文献
34.
The effects of glycol methacrylate as a dehydrating agent on the dimensional changes of liver tissue
The dimensional changes of liver sections during the course of processing with glycol methacrylate (GMA) or with ethanol are described. Tissue processing with ethanol served as a control. During prolonged processing steps (24 h each), linear shrinkage of tissue specimens dehydrated with GMA at room temperature was 13.2%. Subsequent infiltration with GMA resulted in trivial swelling, and polymerization in slight shrinkage (2.3%). In comparison, processing with cold GMA resulted in shrinkage during dehydration (about 10.8%), a slight swelling in pure GMA, followed by shrinkage during polymerization (2.2%). Short routine processing schedules resulted in similar shrinkage/swelling patterns, although precise values differed slightly. In all experiments, ethanolic dehydration resulted in smaller dimensional tissue changes than did GMA dehydration. The dimensional changes of tissue sections during stretching on water, mounting and drying compensated for the major part of the shrinkage manifested during processing. 相似文献
35.
A series of long-chain quaternary ammonium halogen esters (UKK-chemicals), quaternary dimethyl tallow epoxypropyl ammonium
halogens (EPK1), quaternary ditallow methyl epoxypropyl ammonium halogens (EPK2), and EPK2 oligomers (EPK2P) were synthesized.
At acidic, neutral, or slightly basic conditions, EPK1-, EPK2-, EPK2P-, and UKK-chemicals operate as cationic chemicals. They
can be used, for example, as stock sizings, surface sizings, or fixatives. Stock sizing, surface sizing, and fixative experiments
indicate that EPK1-, EPK2-, EPK2P-, and UKK-chemicals function at least as well as or better than the corresponding synthetic
chemicals used in papermaking. 相似文献
36.
马丽霞 《东北电力学院学报》2002,22(1):62-64
论述了某厂一级除盐系统阳床工艺特性及调整试验过程,对存在问题进行分析并改进,得到了实际运行最佳方式和参数,取得良好效果。 相似文献
37.
Phenol novolac/poly (4-hydroxyphenylmaleimide) (PHPMI) blends were used as an epoxy resin hardener. The curing behavior of the above system and the thermal and mechanical properties of the cured epoxy resin were studied. It was not necessary to use a curing accelerator for this system, because PHPMI caused acceleration of the curing reaction. The curing mechanism of this system was investigated by using model compounds. Test pieces from the neat resins and the glass fiber reinforced resins were evaluated in terms of thermal and mechanical properties, respectively. It was found that heat resistance and mechanical properties were improved by increasing the amount of PHPMI in the hardener. 相似文献
38.
39.
桐油改性酚醛树脂的结构及固化过程的研究 总被引:8,自引:0,他引:8
通过桐油与苯酚在酸性催化剂存在下反应,然后再在碱性催化剂存在与甲醛反应制得了一种热固性桐油改性酚醛树脂。利用红外光谱,差示扫描量热法分析技术对改性树脂的结构及固化反应过程进行了研究。 相似文献
40.
Two kinds of biosensors for amino acids (one with nonspecific enzyme as bioelement, the other with specific enzyme(s) as bioelement),
including their principles, applications, recent researches and future trends were discussed in detail. 61 references were
given.
A part of work for gaining Ph. D in chemical and biochemical application at FPMs (Mons, Belgique)
Synopsis of the first author Xia Jinlan, Male, born in 1963, now at Facult’e Polytechnique de Mons, Belgique 相似文献