全文获取类型
收费全文 | 652篇 |
免费 | 43篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 8篇 |
综合类 | 5篇 |
化学工业 | 197篇 |
金属工艺 | 5篇 |
机械仪表 | 8篇 |
建筑科学 | 45篇 |
能源动力 | 9篇 |
轻工业 | 100篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 41篇 |
一般工业技术 | 98篇 |
冶金工业 | 86篇 |
原子能技术 | 6篇 |
自动化技术 | 82篇 |
出版年
2024年 | 2篇 |
2023年 | 9篇 |
2022年 | 18篇 |
2021年 | 44篇 |
2020年 | 15篇 |
2019年 | 21篇 |
2018年 | 18篇 |
2017年 | 18篇 |
2016年 | 27篇 |
2015年 | 25篇 |
2014年 | 34篇 |
2013年 | 39篇 |
2012年 | 37篇 |
2011年 | 46篇 |
2010年 | 34篇 |
2009年 | 31篇 |
2008年 | 27篇 |
2007年 | 25篇 |
2006年 | 26篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 20篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 10篇 |
1998年 | 25篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1985年 | 4篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1943年 | 1篇 |
1939年 | 2篇 |
1938年 | 1篇 |
排序方式: 共有696条查询结果,搜索用时 258 毫秒
1.
Katja F. Hellendahl Felix Kaspar Dr. Xinrui Zhou Zhaoyi Yang Prof. Dr. Zhen Huang Prof. Dr. Peter Neubauer Dr. Anke Kurreck 《Chembiochem : a European journal of chemical biology》2021,22(11):2002-2009
Selenium-modified nucleosides are powerful tools to study the structure and function of nucleic acids and their protein interactions. The widespread application of 2-selenopyrimidine nucleosides is currently limited by low yields in established synthetic routes. Herein, we describe the optimization of the synthesis of 2-Se-uridine and 2-Se-thymidine derivatives by thermostable nucleoside phosphorylases in transglycosylation reactions using natural uridine or thymidine as sugar donors. Reactions were performed at 60 or 80 °C and at pH 9 under hypoxic conditions to improve the solubility and stability of the 2-Se-nucleobases in aqueous media. To optimize the conversion, the reaction equilibria in analytical transglycosylation reactions were studied. The equilibrium constants of phosphorolysis of the 2-Se-pyrimidines were between 5 and 10, and therefore differ by an order of magnitude from the equilibrium constants of any other known case. Hence, the thermodynamic properties of the target nucleosides are inherently unfavorable, and this complicates their synthesis significantly. A tenfold excess of sugar donor was needed to achieve 40−48 % conversion to the target nucleoside. Scale-up of the optimized conditions provided four Se-containing nucleosides in 6–40 % isolated yield, which compares favorably to established chemical routes. 相似文献
2.
3.
C. Brinkmann 《Journal of Materials Science》1986,21(5):1615-1624
The metallization of insulating materials has gained great importance during the last few years. Vaporization in a high vacuum is increasingly employed. Today, glass, ceramic materials, and also organic insulating materials can be coated with a metal layer. While the coating of inorganic insulating materials is comparatively simple, the coating of organic materials causes difficulties. However, organic insulating materials with a metal layer offer a great variety of interesting new technical applications, e.g. in foil-type capacitors which require very thin foils. Nevertheless, during operation several problems can arise. 相似文献
4.
5.
6.
Brillouin scattering (BS), photon correlation spectroscopy (PCS), and ultrasonic (US) measurements were conducted to study the curing process of diglycidyl ether of bisphenol A with butane-1,4-diol at a curing temperature of 100°C. The experimental techniques probe the primary glass-rubber transition during the curing reaction. The primary relaxation time τ obtained from the BS and US velocity and absorption increases with curing time and hence the BS experiment measures τ at earlier stages of cure than the US experiment. The relaxation times at a different extent of reaction and for different measuring temperatures are consistent with BS, US, PCS, and DSC measurements and conform to a single reduced Vogel–Fulcher–Hesse–Tamann equation. Furthermore, the US experiments show evidence of secondary relaxations in the epoxy system. 相似文献
7.
The exponential growth of Internet during the last decade leads us to make more efforts in the researching and developing of sustainable Web servers in order to decrease the global energy demand. In this paper, we cover, as a first step, a proper review of the literature related to the energy efficiency research in Web server systems to depict the state of the art to plan further contributions as more research in sustainable Web systems. We also propose and implement an energy metric that permits to establish a relation between the Quality of Service (QoS) obtained by the system and the power it consumes. 相似文献
8.
9.
10.
We describe the first shared task for figurative language resolution, which was organised within SemEval-2007 and focused
on metonymy. The paper motivates the linguistic principles of data sampling and annotation and shows the task’s feasibility
via human agreement. The five participating systems mainly used supervised approaches exploiting a variety of features, of
which grammatical relations proved to be the most useful. We compare the systems’ performance to automatic baselines as well
as to a manually simulated approach based on selectional restriction violations, showing some limitations of this more traditional
approach to metonymy recognition. The main problem supervised systems encountered is data sparseness, since metonymies in
general tend to occur more rarely than literal uses. Also, within metonymies, the reading distribution is skewed towards a
few frequent metonymy types. Future task developments should focus on addressing this issue.
相似文献
Malvina NissimEmail: |