全文获取类型
收费全文 | 1107篇 |
免费 | 74篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 16篇 |
化学工业 | 228篇 |
金属工艺 | 13篇 |
机械仪表 | 17篇 |
建筑科学 | 52篇 |
矿业工程 | 2篇 |
能源动力 | 40篇 |
轻工业 | 199篇 |
水利工程 | 6篇 |
石油天然气 | 5篇 |
无线电 | 97篇 |
一般工业技术 | 158篇 |
冶金工业 | 98篇 |
原子能技术 | 7篇 |
自动化技术 | 244篇 |
出版年
2024年 | 3篇 |
2023年 | 13篇 |
2022年 | 28篇 |
2021年 | 42篇 |
2020年 | 30篇 |
2019年 | 34篇 |
2018年 | 34篇 |
2017年 | 44篇 |
2016年 | 38篇 |
2015年 | 35篇 |
2014年 | 58篇 |
2013年 | 93篇 |
2012年 | 90篇 |
2011年 | 102篇 |
2010年 | 82篇 |
2009年 | 69篇 |
2008年 | 65篇 |
2007年 | 36篇 |
2006年 | 40篇 |
2005年 | 28篇 |
2004年 | 21篇 |
2003年 | 19篇 |
2002年 | 28篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1998年 | 34篇 |
1997年 | 24篇 |
1996年 | 14篇 |
1995年 | 7篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1980年 | 4篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 5篇 |
排序方式: 共有1182条查询结果,搜索用时 15 毫秒
1.
Scientometrics - The interdisciplinary nature of library and information science (LIS) research has been highlighted for some time now. The term “interdisciplinary” is used primarily in... 相似文献
2.
In this work, we examine the effect of small additions of cationic quaternary ammonium salts (QAS) of different molecular weight on the rheology of an industrial ceramic suspension deflocculated with sodium polyacrylate and sodium metasilicate. The observed shear thinning behaviors obey the typical power law of fluid rheology. In order to characterize the rheological behavior of these slurries, three new parameters are introduced: a low shear rate consistency index and two transient viscosities, distant from the equilibrium, after increasing and decreasing the shear rates. These parameters vary with polyacrylate molecular weight and on additions of small quantities of QAS, which we found to be useful for decreasing the slurry viscosity. 相似文献
3.
4.
5.
Fibrinogen as a cardiovascular risk factor in Spanish children and adolescents. The Ni?o Jesus Group
Studies done on adults reveal a significant role of fibrinogen (FG) in cardiovascular disease. The main purpose of our study was to determine the level of plasma FG in children, its distribution according to age and sex, and its relationship to other cardiovascular risk factors such as cigarette smoking, plasma lipid disturbances, and a positive family history for other cardiovascular risk factors. We studied a population of 2224 children, aged 2 to 18 years, from five different schools located in Madrid. We found a significantly higher level of FG in the groups of females aged 6 to 8 and 16 to 18 years than in males of the same ages (p < 0.001). The study population was distributed into two groups according to the plasma fibrinogen level: > 394 mg/dl and < 394 mg/dl. In both groups we determined plasma levels of total cholesterol, triglycerides, and very low-density lipoprotein (VLDL) cholesterol and found these parameters significantly higher in the group with an FG level > 394 mg/dl (p < 0.05). 相似文献
6.
7.
A liquid-vapor interface in thermal equilibrium was considered, where the pressure tensor depends upon the density (z) and the position z. The surface tension coefficient results are parametrized with the bulk compressibility, liquid-vapor density difference, and interfacial width along the saturation curve. Previous results at the triple and critical points reported by other investigators are verified. Also included is a plot of the computed results using the parametric equation and experimental data for different substances. 相似文献
8.
Lucia Garcia-Garcia Laia Olle Margarita Martin Jordi Roca-Ferrer Rosa Muoz-Cano 《International journal of molecular sciences》2021,22(10)
Adenosine is a nucleoside involved in the pathogenesis of allergic diseases. Its effects are mediated through its binding to G protein-coupled receptors: A1, A2a, A2b and A3. The receptors differ in the type of G protein they recruit, in the effect on adenylyl cyclase (AC) activity and the downstream signaling pathway triggered. Adenosine can produce both an enhancement and an inhibition of mast cell degranulation, indicating that adenosine effects on these receptors is controversial and remains to be clarified. Depending on the study model, A1, A2b, and A3 receptors have shown anti- or pro-inflammatory activity. However, most studies reported an anti-inflammatory activity of A2a receptor. The precise knowledge of the adenosine mechanism of action may allow to develop more efficient therapies for allergic diseases by using selective agonist and antagonist against specific receptor subtypes. 相似文献
9.
Paula Bracco Hein J. Wijma Bastian Nicolai Jhon Alexander Rodriguez Buitrago Thomas Klünemann Agustina Vila Patrick Schrepfer Wulf Blankenfeldt Dick B. Janssen Prof. Dr. Anett Schallmey 《Chembiochem : a European journal of chemical biology》2021,22(6):1099-1110
CYP154C5 from Nocardia farcinica is a P450 monooxygenase able to hydroxylate a range of steroids with high regio- and stereoselectivity at the 16α-position. Using protein engineering and substrate modifications based on the crystal structure of CYP154C5, an altered regioselectivity of the enzyme in steroid hydroxylation had been achieved. Thus, conversion of progesterone by mutant CYP154C5 F92A resulted in formation of the corresponding 21-hydroxylated product 11-deoxycorticosterone in addition to 16α-hydroxylation. Using MD simulation, this altered regioselectivity appeared to result from an alternative binding mode of the steroid in the active site of mutant F92A. MD simulation further suggested that the entrance of water to the active site caused higher uncoupling in this mutant. Moreover, exclusive 15α-hydroxylation was observed for wild-type CYP154C5 in the conversion of 5α-androstan-3-one, lacking an oxy-functional group at C17. Overall, our data give valuable insight into the structure–function relationship of this cytochrome P450 monooxygenase for steroid hydroxylation. 相似文献
10.
L. Rodríguez-Liñares M.J. Lado X.A. Vila A.J. Méndez P. Cuesta 《Computer methods and programs in biomedicine》2014
In this paper, the gHRV software tool is presented. It is a simple, free and portable tool developed in python for analysing heart rate variability. It includes a graphical user interface and it can import files in multiple formats, analyse time intervals in the signal, test statistical significance and export the results. 相似文献