全文获取类型
收费全文 | 13525篇 |
免费 | 402篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 126篇 |
综合类 | 46篇 |
化学工业 | 1913篇 |
金属工艺 | 268篇 |
机械仪表 | 171篇 |
建筑科学 | 662篇 |
矿业工程 | 35篇 |
能源动力 | 184篇 |
轻工业 | 5819篇 |
水利工程 | 55篇 |
石油天然气 | 9篇 |
无线电 | 524篇 |
一般工业技术 | 1631篇 |
冶金工业 | 1058篇 |
原子能技术 | 63篇 |
自动化技术 | 1380篇 |
出版年
2021年 | 175篇 |
2020年 | 162篇 |
2019年 | 170篇 |
2018年 | 206篇 |
2017年 | 165篇 |
2016年 | 258篇 |
2015年 | 223篇 |
2014年 | 284篇 |
2013年 | 474篇 |
2012年 | 423篇 |
2011年 | 556篇 |
2010年 | 383篇 |
2009年 | 373篇 |
2008年 | 434篇 |
2007年 | 437篇 |
2006年 | 250篇 |
2005年 | 269篇 |
2004年 | 228篇 |
2003年 | 192篇 |
2002年 | 164篇 |
1999年 | 124篇 |
1998年 | 194篇 |
1997年 | 160篇 |
1996年 | 139篇 |
1995年 | 132篇 |
1993年 | 132篇 |
1990年 | 134篇 |
1989年 | 128篇 |
1988年 | 113篇 |
1987年 | 135篇 |
1985年 | 143篇 |
1984年 | 138篇 |
1977年 | 142篇 |
1976年 | 132篇 |
1974年 | 110篇 |
1973年 | 110篇 |
1970年 | 115篇 |
1917年 | 120篇 |
1916年 | 129篇 |
1915年 | 125篇 |
1913年 | 138篇 |
1912年 | 188篇 |
1911年 | 132篇 |
1910年 | 135篇 |
1909年 | 141篇 |
1908年 | 133篇 |
1907年 | 130篇 |
1906年 | 132篇 |
1905年 | 130篇 |
1904年 | 120篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Dr. Christine Brotschi Dr. Martin H. Bolli Dr. John Gatfield Dr. Bibia Heidmann Dr. Francois Jenck Dr. Catherine Roch Dr. Thierry Sifferlen Dr. Alexander Treiber Dr. Jodi T. Williams Dr. Christoph Boss 《ChemMedChem》2020,15(5):430-448
The orexin system is responsible for regulating the sleep-wake cycle. Suvorexant, a dual orexin receptor antagonist (DORA) is approved by the FDA for the treatment of insomnia disorders. Herein, we report the optimization efforts toward a DORA, where our starting point was (5-methoxy-4-methyl-2-[1,2,3]triazol-2-yl-phenyl)-{(S)-2-[5-(2-trifluoromethoxy-phenyl)-[1,2,4]oxadiazol-3-yl]-pyrrolidin-1-yl}methanone ( 6 ), a compound which emerged from our in-house research program. Compound 6 was shown to be a potent, brain-penetrating DORA with in vivo efficacy similar to suvorexant in rats. However, shortcomings from low metabolic stability, high plasma protein binding (PPB), low brain free fraction (fu brain), and low aqueous solubility, were identified and hence, compound 6 was not an ideal candidate for further development. Our optimization efforts addressing the above-mentioned shortcomings resulted in the identification of (4-chloro-2-[1,2,3]triazol-2-yl-phenyl)-{(S)-2-methyl-2-[5-(2-trifluoromethoxy-phenyl)-4H-[1,2,4]triazol-3-yl]-pyrrolidin-1-yl}l-methanone ( 42 ), a DORA with improved in vivo efficacy compared to 6 . 相似文献
2.
Nano design for macroscopic coatings – new application potentials by PVD coatings up to 100 μm thickness Non-homogeneous coatings still limit the application of thicker layers due to defect growth and irregular layer thickness distribution along the surface of complex shaped components. Therefore, the layer thickness is usually limited to about 10 μm. In order to limit the surface roughness by the growing layer, multilayer coating systems are deposited by highly ionized plasmas. This allows significantly smoother layers to be produced, which until now could only be produced by mechanical finishing. Furthermore, by combining selected material systems and targeted parameter selection, structures can be deposited during coating, especially on edges, which result in a reduction of the cutting edge radius. In future, edge geometries should therefore be able to be specifically adjusted through the coating process. 相似文献
3.
4.
5.
6.
Adrian Caspari Christoph Offermanns Pascal Schäfer Adel Mhamdi Alexander Mitsos 《American Institute of Chemical Engineers》2019,65(11):e16705
The flexible operation of energy-intensive processes, such as cryogenic air separation, has economic potential due to increasing fluctuations of the electricity markets. Multiproduct air separation processes with high ratios of liquid product are very promising for flexible operation due to storable products. We present a process design with an integrated liquefication cycle and liquid assist operation, that facilitates a high liquid product ratio and a flexible process operation. We use a mechanistic dynamic process model in steady-state process optimizations covering the wide operational range of the proposed process. The optimization results show that the power demand can be varied in a range from 3.5 to 28 MW without violating operational constraints by changing the nitrogen and oxygen production rates. Thus, the proposed process is a promising air separation candidate for flexible operation with respect to fluctuating electricity markets. 相似文献
7.
8.
9.
Tran Thi Ngoc Trang Felfernig Alexander Trattner Christoph Holzinger Andreas 《Journal of Intelligent Information Systems》2021,57(1):171-201
Journal of Intelligent Information Systems - Nowadays, a vast amount of clinical data scattered across different sites on the Internet hinders users from finding helpful information for their... 相似文献
10.
Leibetseder Andreas Schoeffmann Klaus Keckstein Jörg Keckstein Simon 《Multimedia Tools and Applications》2022,81(5):6191-6215
Multimedia Tools and Applications - Endometriosis is a common gynecologic condition typically treated via laparoscopic surgery. Its visual versatility makes it hard to identify for non-specialized... 相似文献