全文获取类型
收费全文 | 244403篇 |
免费 | 23528篇 |
国内免费 | 13665篇 |
专业分类
电工技术 | 17253篇 |
技术理论 | 14篇 |
综合类 | 23647篇 |
化学工业 | 28599篇 |
金属工艺 | 13158篇 |
机械仪表 | 22267篇 |
建筑科学 | 25541篇 |
矿业工程 | 8774篇 |
能源动力 | 9994篇 |
轻工业 | 21023篇 |
水利工程 | 9484篇 |
石油天然气 | 10456篇 |
武器工业 | 2781篇 |
无线电 | 15935篇 |
一般工业技术 | 27032篇 |
冶金工业 | 10072篇 |
原子能技术 | 3473篇 |
自动化技术 | 32093篇 |
出版年
2024年 | 1153篇 |
2023年 | 3555篇 |
2022年 | 6694篇 |
2021年 | 7706篇 |
2020年 | 8092篇 |
2019年 | 6956篇 |
2018年 | 6843篇 |
2017年 | 8277篇 |
2016年 | 9421篇 |
2015年 | 9791篇 |
2014年 | 15136篇 |
2013年 | 15890篇 |
2012年 | 17806篇 |
2011年 | 19466篇 |
2010年 | 13857篇 |
2009年 | 14138篇 |
2008年 | 13279篇 |
2007年 | 15986篇 |
2006年 | 14098篇 |
2005年 | 11775篇 |
2004年 | 9859篇 |
2003年 | 8432篇 |
2002年 | 6942篇 |
2001年 | 5763篇 |
2000年 | 4962篇 |
1999年 | 4147篇 |
1998年 | 3533篇 |
1997年 | 3028篇 |
1996年 | 2538篇 |
1995年 | 2064篇 |
1994年 | 1847篇 |
1993年 | 1453篇 |
1992年 | 1274篇 |
1991年 | 912篇 |
1990年 | 818篇 |
1989年 | 648篇 |
1988年 | 576篇 |
1987年 | 366篇 |
1986年 | 341篇 |
1985年 | 308篇 |
1984年 | 335篇 |
1983年 | 297篇 |
1982年 | 265篇 |
1981年 | 113篇 |
1980年 | 130篇 |
1979年 | 100篇 |
1978年 | 64篇 |
1977年 | 55篇 |
1976年 | 49篇 |
1959年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
从控制和保证压力容器类焊接产品质量角度出发,通过分析其在制造过程中每道工序可能出现的质量问题,总结出这类产品在制造过程质量分析的要领及内容,提出了质量控制的关键,为制定焊接检验方案提供依据。 相似文献
92.
This paper deals with the decomposition analysis of energy-related CO2 emissions in Greece from 1990 to 2002. The Arithmetic Mean Divisia Index (AMDI) and the Logarithmic Mean Divisia Index (LMDI) techniques are applied and changes in CO2 emissions are decomposed into four factors: income effect, energy intensity effect, fuel share effect and population effect. The period-wise and time series analyses show that the biggest contributor to the rise in CO2 emissions in Greece is the income effect; on the contrary, the energy intensity effect is mainly responsible for the decrease in CO2 emissions. A comparison of the results of the two techniques gave an insight in the intricacies of energy decomposition. Finally, conclusions and future areas of research are presented. 相似文献
93.
Many approaches have been proposed to enhance software productivity and reliability. These approaches typically fall into three categories: the engineering approach, the formal approach and the knowledge-based approach. But the optimal gain in software productivity cannot be obtained if one relies on only one of these approaches. This paper describes the work in knowledge-based software engineering conducted by the authors for the past 10 years. The final goal of the research is to develop a paradigm for software engineering which integrates the three approaches mentioned above. A knowledge-based tool which can support the whole process of software development is provided in this paper. 相似文献
94.
95.
96.
97.
98.
Patrick DAstous Franoise Dtienne Willemien Visser Pierre N. Robillard 《Design Studies》2004,25(6):625-655
By contrast to design meetings, design evaluation meetings (DEMs) have generally been considered as situations in which, according to DEM methodologies, design activities are quite marginal. In a study of DEMs in software development, i.e. in technical review meetings following a particular review methodology, we showed: (i) the occurrence of design activities as part of an argumentation process; (ii) the relative importance of cognitive synchronisation as a prerequisite for evaluation; (iii) the important role played in evaluation by argumentation that makes explicit the underlying design rationale (DR). On the basis of our results, we discuss the potential for using DR methodologies in this kind of meetings. 相似文献
99.
Boiling: Size Distribution of Bubbles as Demanded by the Principle of Maximum Information 总被引:1,自引:0,他引:1
The principle of maximum informational entropy is used to find the probability density function for the departure radius of a bubble in boiling on a solid surface. A general relation is derived, which leads to particular expressions. 相似文献
100.
This study investigates the relationship between the critical surface tension of wetting of celestite and agglomeration recovery as well as the zeta potential in dependence of pH and amount of collector (Na‐Oleate). For this purpose, effects of pH and collector amount on the agglomeration recovery are investigated and zeta potential measurements and Fourier Transform Infrared Spectrophotometer (FTIR) analyses are carried out to determine the adsorption type of Na‐Oleate on celestite surface. The sessile drop technique is used for the measurement of contact angle and determination of the critical surface tension of wetting (YC) of celestite. The maximum agglomeration recovery is obtained at pH 7. The critical surface tension of wetting of celestite is very close to the surface tension of kerosene, which is 25.95 mN/m. Furthermore, at the optimum Na‐Oleate amount of 10 kg/ton, the critical surface tension of wetting of celestite is approximately equal to the surface tension of kerosene. 相似文献