全文获取类型
收费全文 | 10434篇 |
免费 | 530篇 |
国内免费 | 53篇 |
专业分类
电工技术 | 226篇 |
综合类 | 22篇 |
化学工业 | 2530篇 |
金属工艺 | 177篇 |
机械仪表 | 239篇 |
建筑科学 | 366篇 |
矿业工程 | 8篇 |
能源动力 | 567篇 |
轻工业 | 1336篇 |
水利工程 | 125篇 |
石油天然气 | 162篇 |
武器工业 | 4篇 |
无线电 | 1074篇 |
一般工业技术 | 1776篇 |
冶金工业 | 748篇 |
原子能技术 | 85篇 |
自动化技术 | 1572篇 |
出版年
2024年 | 28篇 |
2023年 | 245篇 |
2022年 | 629篇 |
2021年 | 776篇 |
2020年 | 477篇 |
2019年 | 487篇 |
2018年 | 616篇 |
2017年 | 445篇 |
2016年 | 484篇 |
2015年 | 347篇 |
2014年 | 468篇 |
2013年 | 782篇 |
2012年 | 558篇 |
2011年 | 658篇 |
2010年 | 403篇 |
2009年 | 383篇 |
2008年 | 347篇 |
2007年 | 329篇 |
2006年 | 259篇 |
2005年 | 224篇 |
2004年 | 179篇 |
2003年 | 153篇 |
2002年 | 155篇 |
2001年 | 74篇 |
2000年 | 83篇 |
1999年 | 99篇 |
1998年 | 140篇 |
1997年 | 129篇 |
1996年 | 85篇 |
1995年 | 89篇 |
1994年 | 60篇 |
1993年 | 59篇 |
1992年 | 51篇 |
1991年 | 24篇 |
1990年 | 36篇 |
1989年 | 50篇 |
1988年 | 56篇 |
1987年 | 34篇 |
1986年 | 35篇 |
1985年 | 51篇 |
1984年 | 54篇 |
1983年 | 49篇 |
1982年 | 33篇 |
1981年 | 25篇 |
1980年 | 30篇 |
1979年 | 25篇 |
1978年 | 20篇 |
1977年 | 27篇 |
1976年 | 34篇 |
1973年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
We propose a new formulation of quantum algorithm which allows to distribute amplitudes over two copies of small quantum subsystems. The new method gives a fixed number of copies and applied to the control of multi-qubit system. The analysis for the amount of error due to the distribution process has been presented for a system of 10 qubits with a small quantum subsystems to be copied. The present scheme provides a new way to distribute amplitudes over small quantum subsystems. 相似文献
12.
13.
M. S. Rizk Y. M. Issa M. A. Ahmed S. M. Shaaban 《Journal of Materials Science: Materials in Electronics》1993,4(2):109-112
The charge transfer complexes produced by the reaction between picric acid and some aniline derivatives were prepared. The prepared charge transfer complexes (CTC) were investigated using infrared and nuclear magnetic resonance spectroscopy aiming to throw more light on their molecular structure. It was proved that a proton transfer interaction takes place between PiOH and x-Ph.NH2 leading to the formation of PiO} and x-Ph.NH3
+ ions. The normal -1 electronic interaction takes place by transferring an electron from the aniline ring to the picric acid. The semiconducting properties of the CTC were investigated. All the prepared complexes were proved to have a semiconducting character within the temperature range investigated. 相似文献
14.
15.
Jaffee Sara R.; Caspi Avshalom; Moffitt Terrie E.; Taylor Alan 《Canadian Metallurgical Quarterly》2004,113(1):44
The well-documented finding that child physical maltreatment predicts later antisocial behavior has at least 2 explanations: (a) Physical maltreatment causes antisocial behavior, and (b) genetic factors transmitted from parents to children influence the likelihood that parents will be abusive and that children will engage in antisocial behavior. The authors tested these hypotheses in the representative Environmental-Risk cohort of 1,116 twin pairs and their families, who were assessed when the twins were 5 and 7 years old. Mothers reported on children's experience of physical maltreatment, and mothers and teachers reported on children's antisocial behavior. The findings support the hypothesis that physical maltreatment plays a causal role in the development of children's antisocial behavior and that preventing maltreatment can prevent its violent sequelae. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
16.
Numerical simulations were performed to determine the effect of Reynolds number and orifice to pipe diameter ratio (do/d) on the wall mass transfer rate downstream of an orifice. The simulations were performed for do/d of 0.475 for Reynolds number up to 70,000. The effect of do/d was determined by performing simulations at a Reynolds number of 70,000 for do/d of 0.375, 0.475 and 0.575. The momentum and mass transport equations were solved using the Low Reynolds Number (LRN) K-? turbulence model. The Sherwood number (Sh) profile downstream of the orifice was in relatively good agreement with existing experimental results. The Sh increases sharply downstream of the orifice, reaching a maximum within 1–2 diameters downstream of the orifice, before relaxing back to the fully developed pipe flow value. The Sh number well downstream of the orifice was in good agreement with results for fully developed pipe flow estimated from the correlation of Berger and Hau (1977). The peak Sh numbers from the simulations were higher than that predicted from Tagg et al. (1979) and Coney (1980). 相似文献
17.
18.
Daniel Villalobos-García Hamdy E. A. Ali Ahmed B. Alarabi Medhat S. El-Halawany Fatima Z. Alshbool Fadi T. Khasawneh 《International journal of molecular sciences》2022,23(10)
Smoking is a risk factor for a variety of deleterious conditions, such as cancer, respiratory disease and cardiovascular disease. Thrombosis is an important and common aspect of several cardiovascular disease states, whose risk is known to be increased by both first- and secondhand smoke. More recently, the residual cigarette smoke that persists after someone has smoked (referred to as thirdhand smoke or THS) has been gaining more attention, since it has been shown that it also negatively affects health. Indeed, we have previously shown that 6-month exposure to THS increases the risk of thrombogenesis. However, neither the time-dependence of THS-induced thrombus formation, nor its sex dependence have been investigated. Thus, in the present study, we investigated these issues in the context of a shorter exposure to THS, specifically 3 months, in male and female mice. We show that the platelets from 3-month THS-exposed mice exhibited enhanced activation by agonists. Moreover, we also show that mice of both sexes exposed to THS have decreased tail bleeding as well as decreased thrombus occlusion time. In terms of the role of sex, intersex disparities in thrombus development and hemostasis as well as in platelet aggregation were, interestingly, observed. Together, our findings show that exposing mice to THS for 3 months is sufficient to predispose them to thrombosis; which seems to be driven, at least in part, by an increased activity in platelets, and that it does not manifest equally in both sexes. 相似文献
19.
Sara Oliveira Tamaeh Monteiro-Alfredo Rita Henriques Carlos Fontes Ribeiro Raquel Seia Teresa Cruz Clia Cabral Rosa Fernandes Ftima Piedade Maria Paula Robalo Paulo Matafome Snia Silva 《International journal of molecular sciences》2022,23(10)
Curcumin has been suggested as a promising treatment for metabolic diseases, but the high doses required limit its therapeutic use. In this study, a new curcuminoid is synthesised to increase curcumin anti-inflammatory and antioxidant potential and to achieve hypoglycaemic and protective vascular effects in type 2 diabetic rats in a lower dose. In vitro, the anti-inflammatory effect was determined through the Griess reaction, and the antioxidant activity through ABTS and TBARS assays. In vivo, Goto-Kakizaki rats were treated for 2 weeks with the equimolar dose of curcumin (40 mg/kg/day) or curcuminoid (52.4 mg/kg/day). Fasting glycaemia, insulin tolerance, plasma insulin, insulin signalling, serum FFA, endothelial function and several markers of oxidative stress were evaluated. Both compounds presented a significant anti-inflammatory effect. Moreover, the curcuminoid had a marked hypoglycaemic effect, accompanied by higher GLUT4 levels in adipose tissue. Both compounds increased NO-dependent vasorelaxation, but only the curcuminoid exacerbated the response to ascorbic acid, consistent with a higher decrease in vascular oxidative and nitrosative stress. SOD1 and GLO1 levels were increased in EAT and heart, respectively. Altogether, these data suggest that the curcuminoid developed here has more pronounced effects than curcumin in low doses, improving the oxidative stress, endothelial function and glycaemic profile in type 2 diabetes. 相似文献
20.
Laura Mannarino Lara Paracchini Federica Pezzuto Gheorghe Emilian Olteanu Laura Moracci Luca Vedovelli Irene De Simone Cristina Bosetti Monica Lupi Rosy Amodeo Alessia Inglesi Maurizio Callari Serena Penpa Roberta Libener Sara Delfanti Antonina De Angelis Alberto Muzio Paolo Andrea Zucali Paola Allavena Giovanni Luca Ceresoli Sergio Marchini Fiorella Calabrese Maurizio DIncalci Federica Grosso 《International journal of molecular sciences》2022,23(10)