全文获取类型
收费全文 | 290107篇 |
免费 | 18687篇 |
国内免费 | 9976篇 |
专业分类
电工技术 | 13602篇 |
技术理论 | 24篇 |
综合类 | 14226篇 |
化学工业 | 47913篇 |
金属工艺 | 17138篇 |
机械仪表 | 16834篇 |
建筑科学 | 18656篇 |
矿业工程 | 7663篇 |
能源动力 | 8405篇 |
轻工业 | 16780篇 |
水利工程 | 4060篇 |
石油天然气 | 17991篇 |
武器工业 | 1652篇 |
无线电 | 31138篇 |
一般工业技术 | 42974篇 |
冶金工业 | 23098篇 |
原子能技术 | 3229篇 |
自动化技术 | 33387篇 |
出版年
2024年 | 789篇 |
2023年 | 3682篇 |
2022年 | 6163篇 |
2021年 | 9306篇 |
2020年 | 7198篇 |
2019年 | 6337篇 |
2018年 | 8054篇 |
2017年 | 8898篇 |
2016年 | 8062篇 |
2015年 | 9672篇 |
2014年 | 12371篇 |
2013年 | 16458篇 |
2012年 | 16344篇 |
2011年 | 18456篇 |
2010年 | 15554篇 |
2009年 | 15182篇 |
2008年 | 14757篇 |
2007年 | 14387篇 |
2006年 | 14442篇 |
2005年 | 14684篇 |
2004年 | 10132篇 |
2003年 | 8614篇 |
2002年 | 7122篇 |
2001年 | 6470篇 |
2000年 | 6865篇 |
1999年 | 7913篇 |
1998年 | 8697篇 |
1997年 | 6867篇 |
1996年 | 6259篇 |
1995年 | 4886篇 |
1994年 | 3891篇 |
1993年 | 3012篇 |
1992年 | 2309篇 |
1991年 | 1973篇 |
1990年 | 1579篇 |
1989年 | 1350篇 |
1988年 | 1000篇 |
1987年 | 806篇 |
1986年 | 675篇 |
1985年 | 623篇 |
1984年 | 466篇 |
1983年 | 423篇 |
1982年 | 443篇 |
1981年 | 421篇 |
1980年 | 430篇 |
1979年 | 385篇 |
1977年 | 443篇 |
1976年 | 683篇 |
1975年 | 328篇 |
1973年 | 334篇 |
排序方式: 共有10000条查询结果,搜索用时 765 毫秒
91.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii 下载免费PDF全文
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献
92.
Thermoresponsive behavior and rheology of SiO2–hyaluronic acid/poly(N‐isopropylacrylamide) (NaHA/PNIPAm) core–shell structured microparticles 下载免费PDF全文
93.
94.
95.
96.
Dongdong Ji Zheng Liu Bailing Jiang Xiaofei Luo 《International Journal of Hydrogen Energy》2021,46(27):13960-13970
The evaluation of cell's weatherability is of practical interest. To further improve the soluble lead flow battery's weatherability, physiochemical properties of electrolytes containing fluoborate, perchlorate, methanesulfonate and trifluoromethanesulfonate are investigated from ?60 to 50 °C. Activities of CF3SO3H and HClO4 are poor in trifluoromethanesulfonate and perchlorate solutions due to common anion effect. The solubility of lead salt can be improved by increasing temperature, but worsened by increasing acid's content. With the temperature increasing, the conductivity is enhanced, and the viscosity is lowered for four solutions. The same results have been found by increasing acid's content except for CF3SO3H. The high energy efficiency can be achieved for cells over ?40–0 °C using fluoborate and perchlorate solutions, 73.2% at ?40 °C and 78.1% at ?30 °C respectively. Over the temperature range of 20–50 °C, the cells with methanesulfonate and trifluoromethanesulfonate solutions have good performance, 77.4% and 73.7% at 50 °C respectively. 相似文献
97.
Lissy Z. F. Gross Mariana Sacerdoti Prof. Albrecht Piiper Prof. Stefan Zeuzem Dr. Alejandro E. Leroux Dr. Ricardo M. Biondi 《ChemMedChem》2020,15(18):1682-1690
Angiotensin converting enzyme 2 (ACE2) is the human receptor that interacts with the spike protein of coronaviruses, including the one that produced the 2020 coronavirus pandemic (COVID-19). Thus, ACE2 is a potential target for drugs that disrupt the interaction of human cells with SARS-CoV-2 to abolish infection. There is also interest in drugs that inhibit or activate ACE2, that is, for cardiovascular disorders or colitis. Compounds binding at alternative sites could allosterically affect the interaction with the spike protein. Herein, we review biochemical, chemical biology, and structural information on ACE2, including the recent cryoEM structures of full-length ACE2. We conclude that ACE2 is very dynamic and that allosteric drugs could be developed to target ACE2. At the time of the 2020 pandemic, we suggest that available ACE2 inhibitors or activators in advanced development should be tested for their ability to allosterically displace the interaction between ACE2 and the spike protein. 相似文献
98.
99.
Silicon - Following our interest in exotic silylenes, here we compare and contrast 20 novel five-membered cyclic silylenes, including saturated (sila)0–4 cyclopentasilylenes (1–10) and... 相似文献
100.