全文获取类型
收费全文 | 19638篇 |
免费 | 1209篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 129篇 |
综合类 | 115篇 |
化学工业 | 5486篇 |
金属工艺 | 468篇 |
机械仪表 | 377篇 |
建筑科学 | 658篇 |
矿业工程 | 52篇 |
能源动力 | 725篇 |
轻工业 | 4411篇 |
水利工程 | 157篇 |
石油天然气 | 157篇 |
武器工业 | 1篇 |
无线电 | 815篇 |
一般工业技术 | 2796篇 |
冶金工业 | 1972篇 |
原子能技术 | 137篇 |
自动化技术 | 2433篇 |
出版年
2024年 | 54篇 |
2023年 | 198篇 |
2022年 | 706篇 |
2021年 | 872篇 |
2020年 | 553篇 |
2019年 | 600篇 |
2018年 | 756篇 |
2017年 | 738篇 |
2016年 | 822篇 |
2015年 | 590篇 |
2014年 | 910篇 |
2013年 | 1681篇 |
2012年 | 1306篇 |
2011年 | 1427篇 |
2010年 | 1091篇 |
2009年 | 1068篇 |
2008年 | 893篇 |
2007年 | 790篇 |
2006年 | 600篇 |
2005年 | 484篇 |
2004年 | 431篇 |
2003年 | 434篇 |
2002年 | 342篇 |
2001年 | 267篇 |
2000年 | 220篇 |
1999年 | 233篇 |
1998年 | 751篇 |
1997年 | 498篇 |
1996年 | 335篇 |
1995年 | 203篇 |
1994年 | 183篇 |
1993年 | 138篇 |
1992年 | 72篇 |
1991年 | 45篇 |
1990年 | 42篇 |
1989年 | 51篇 |
1988年 | 56篇 |
1987年 | 47篇 |
1986年 | 27篇 |
1985年 | 45篇 |
1984年 | 31篇 |
1983年 | 27篇 |
1982年 | 27篇 |
1981年 | 22篇 |
1980年 | 36篇 |
1979年 | 18篇 |
1978年 | 19篇 |
1977年 | 29篇 |
1976年 | 53篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
P Sánchez García 《Canadian Metallurgical Quarterly》1997,114(1):157-63; discussion 164-7
45.
The first Brazilian uranium mine and mill are located on the Poços de Caldas plateau, in the Central State of Minas Gerais. The pre-operational environmental survey was carried out over a period of two years by the Brazilian Nuclear Energy Commission (CNEN), through the Instituto de Radioproteção e Dosimetria (IRD). The selection of the materials to be monitored, the sampling points and the radionuclides to be analysed were based on critical parameters taking into account the meteorological and hydrological characteristics of the site as well as land use. The results obtained are sufficient to characterize the environmental background of the area, and will allow an assessment of the environmental impact due to the operation of the facility and an evaluation of the adequacy of the effluent emmission control measures. In relation to their contribution to the population dose, the results indicated that 226Ra and 210Pb will be the important radionuclides. 相似文献
46.
We describe a patient with aspergillosis of the maxillary antrum, and systemic affectation (anemia, anorexia, fever). Through a Caldwell-Luck approach, the maxillary antrum was opened and an irregular mass removed, postoperatively the patient has done well, disappearing in two months the ORL and systemic symptoms. 相似文献
47.
48.
The preparation of p-type amorphous- or microcrystalline silicon often requires the use of a gas mixture containing diborane. Whereas the concentration of this gas in the process chamber is critical for the determination of the doping level, and thus of the properties, of resulting films, it is in practice very difficult to have a proper control of such a concentration owing to the degradation of diborane in the cylinder by polymerisation. The main consequence is a significant lack of reproducibility of results. The present paper analyses the problem and its practical influence, describes a simple diborane-degradation model, proposes certain approaches based thereon and shows experimental results illustrating the validity of the procedures suggested. It is finally concluded that the application of this simple model is a straightforward and effective way to control diborane doping level in p-type amorphous- or microcrystalline silicon. 相似文献
49.
50.
Luengo M. A.; Carrillo-de-la-Pe?a M. T.; Otero J. M.; Romero E. 《Canadian Metallurgical Quarterly》1994,66(3):542
Analyzes the relationships between impulsivity and antisocial behavior in a noninstitutionalized sample, taking into account the multidimensional nature of impulsivity and the diversity of types of antisocial behavior. Data were obtained in 1989 and 1990 from 1,226 adolescents aged 12–18 yrs as part of a longitudinal study of risk factors for drug abuse and delinquency. The patterns of stability or change of the various dimensions of antisocial behavior (rule breaking, vandalism, theft, aggression, and drug taking) in relation to impulsivity were investigated. The results support that self-report measures of impulsivity are closely correlated with antisocial behavior among adolescents. The longitudinally-oriented analysis of this work also shows that impulsivity is associated with a future increase in antisocial behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献