全文获取类型
收费全文 | 21340篇 |
免费 | 882篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 261篇 |
综合类 | 46篇 |
化学工业 | 4711篇 |
金属工艺 | 407篇 |
机械仪表 | 465篇 |
建筑科学 | 1226篇 |
矿业工程 | 56篇 |
能源动力 | 576篇 |
轻工业 | 1860篇 |
水利工程 | 135篇 |
石油天然气 | 57篇 |
武器工业 | 1篇 |
无线电 | 1819篇 |
一般工业技术 | 3707篇 |
冶金工业 | 3160篇 |
原子能技术 | 217篇 |
自动化技术 | 3544篇 |
出版年
2023年 | 209篇 |
2022年 | 382篇 |
2021年 | 590篇 |
2020年 | 445篇 |
2019年 | 478篇 |
2018年 | 530篇 |
2017年 | 503篇 |
2016年 | 633篇 |
2015年 | 533篇 |
2014年 | 694篇 |
2013年 | 1278篇 |
2012年 | 1063篇 |
2011年 | 1391篇 |
2010年 | 962篇 |
2009年 | 997篇 |
2008年 | 1048篇 |
2007年 | 919篇 |
2006年 | 835篇 |
2005年 | 705篇 |
2004年 | 555篇 |
2003年 | 501篇 |
2002年 | 477篇 |
2001年 | 325篇 |
2000年 | 366篇 |
1999年 | 390篇 |
1998年 | 781篇 |
1997年 | 501篇 |
1996年 | 414篇 |
1995年 | 313篇 |
1994年 | 285篇 |
1993年 | 288篇 |
1992年 | 201篇 |
1991年 | 170篇 |
1990年 | 149篇 |
1989年 | 150篇 |
1988年 | 138篇 |
1987年 | 124篇 |
1986年 | 118篇 |
1985年 | 149篇 |
1984年 | 137篇 |
1983年 | 119篇 |
1982年 | 93篇 |
1981年 | 107篇 |
1980年 | 89篇 |
1979年 | 102篇 |
1978年 | 90篇 |
1977年 | 115篇 |
1976年 | 142篇 |
1975年 | 83篇 |
1974年 | 75篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Tindall C.E. Martin J.P. Morrow D.J. Calvert P.A.J. 《Energy Conversion, IEEE Transaction on》1996,11(3):539-546
The use of small alternators, other than for standby purposes, is increasing and this has focused attention on the reliability and utility of the parameters normally quoted for such machines. Test procedures are described and methods used for parameter estimation discussed, with particular emphasis on the difficulties presented by small brushless machines 相似文献
22.
Reduction of optical proximity effects (OPE), at deep uv wavelength of 248nm, caused by the variation of stepper lens operating conditions is investigated. It is shown that many of these effects, which increase as the Rayleigh limit is approached, can be minimised, and in many cases eliminated, by suitable choice of lens numerical aperture (NA) and partial coherence (sigma, σ).
Application of these results should enable the user of advanced wafer steppers to carry out high resolution lithography with a minimum of time consuming optical proximity correction (OPC). 相似文献
23.
More than one hundred samples of European beers have been investigated by the new SNIF-NMR method which is based on 2H NMR at the natural abundance level and enables site-specific natural isotope fractionation factors in ethanol to be determined. The relative (R) and absolute (D/H)i, parameters are shown to be characteristic of the country where the beers are brewed and the observed variations are explained in terms of cereal composition, water resource, and manufacturing processing (fermentation, yeast, temperature cycle). These new parameters find analytical and mechanistic applications in the identification of a beer and in the investigation of a fermentation process. 相似文献
24.
This paper is the result of a plenary discussion session held at the 11th European Conference on Mixing. Three perspectives on mixing research are explored: that of the industrialist, the equipment manufacturer, and the academic researcher. There was strong agreement that, while the one dimensional problems are reasonably well understood and many engineers thus perceive that mixing is simple, current practice actually requires us to address complex, multi‐dimensional problems with interactions between mixing, reaction, multi‐phase physics, surface phenomena, and transport phenomena. Understanding these multi‐scale, multi‐mechanism problems requires models which include interactions between the phenomena, and allow the effects of these interactions to emerge. Developing these models will require us to shift our perspective on mixing from one of equipment design to one of the mixing field as a fundamental physical mechanism. 相似文献
25.
26.
A simplified procedure for computing ohmic losses in secondary distribution cable systems by extending the Neher-McGrath model for 60 Hz losses is presented. Specifically, simplified formulae for evaluating ohmic losses due to harmonics are given. These results are subsequently used to compute the cable ampacity or the derating factor due to harmonics. The overall method is simple to follow and can be performed with a calculator. A typical example is given 相似文献
27.
28.
29.
30.
Matthias Max 《突发事故与危机管理杂志》2021,29(1):2-11
Digitalization and the trend towards more short‐term and project‐oriented social engagement have had a direct impact on traditional crisis management. This societal change has supported the evolution of new types of volunteers who use low‐threshold potentials to organize and maintain support independently. Traditional institutions like the German Red Cross are challenged to deal with these rapid changes regarding their own organizational culture in relation to the new phenomenon of so‐called unaffiliated volunteers. This paper investigates how unaffiliated volunteers influence and change the organizational culture of German disaster management by analysing and reflecting organizational adaptation processes in the aftermath of the German floods in 2013, the storm events in the west of Germany in 2014 and the refugee relief mission in 2015–2016. Therefore, semi‐structured interviews with experts of the German Red Cross were held to analyse their reactions towards unaffiliated Volunteers during the Floods in 2013 and the refugee relief missions, and further focus group interviews were conducted to validate the extracted results. Findings suggest that among professionals and leading entities in the German Red Cross, a process of rethinking has emerged, recognizing the importance and necessity to open up organizational structures for the collaboration and coordination of unaffiliated volunteers. 相似文献