全文获取类型
收费全文 | 682篇 |
免费 | 11篇 |
专业分类
电工技术 | 25篇 |
综合类 | 1篇 |
化学工业 | 114篇 |
金属工艺 | 12篇 |
机械仪表 | 7篇 |
建筑科学 | 37篇 |
矿业工程 | 3篇 |
能源动力 | 53篇 |
轻工业 | 42篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 41篇 |
一般工业技术 | 67篇 |
冶金工业 | 204篇 |
原子能技术 | 6篇 |
自动化技术 | 75篇 |
出版年
2022年 | 3篇 |
2021年 | 9篇 |
2019年 | 5篇 |
2018年 | 13篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 9篇 |
2014年 | 5篇 |
2013年 | 40篇 |
2012年 | 23篇 |
2011年 | 18篇 |
2010年 | 22篇 |
2009年 | 15篇 |
2008年 | 19篇 |
2007年 | 26篇 |
2006年 | 20篇 |
2005年 | 5篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 15篇 |
2001年 | 22篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 42篇 |
1997年 | 20篇 |
1996年 | 28篇 |
1995年 | 21篇 |
1994年 | 16篇 |
1993年 | 20篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 17篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1973年 | 10篇 |
1972年 | 3篇 |
1971年 | 4篇 |
排序方式: 共有693条查询结果,搜索用时 312 毫秒
71.
Klánová J Diamond M Jones K Lammel G Lohmann R Pirrone N Scheringer M Balducci C Bidleman T Bláha K Bláha L Booij K Bouwman H Breivik K Eckhardt S Fiedler H Garrigues P Harner T Holoubek I Hung H MacLeod M Magulova K Mosca S Pistocchi A Simonich S Smedes F Stephanou E Sweetman A Sebková K Venier M Vighi M Vrana B Wania F Weber R Weiss P 《Environmental science & technology》2011,45(18):7617-7619
72.
Chen G.P. Malik O.P. Hope G.S. Qin Y.H. Xu G.Y. 《Energy Conversion, IEEE Transaction on》1993,8(4):639-645
An adaptive power system stabilizer (APSS) employing a new self-optimizing pole shifting control strategy and its application to a power system are described in this paper. Based on an identified model of the system, the control is computed by an algorithm which shifts the closed-loop poles of the system to some optimal locations inside the unit circle in the z-domain to minimize a given performance criterion. With the self-optimization property, outside intervention in the controller design procedure is minimized, thus simplifying the tuning procedure during commissioning. Also, a new method of calculating the variable forgetting factor in real-time parameter identification is discussed. Studies show that the proposed APSS can provide good damping of the power system over a wide operating range and significantly improve the dynamic performance of the system 相似文献
73.
74.
HS Khaira SR Maxwell H Thomason GH Thorpe MA Green CP Shearman 《Canadian Metallurgical Quarterly》1996,83(3):401-403
Ischaemia-reperfusion injury generates oxygen-derived free radicals leading to local and distant damage. A simple method of following oxidative activity is to measure the consumption of endogenous scavenging antioxidants; an enhanced chemiluminescent assay was used to study this phenomenon in 21 patients undergoing surgery for abdominal aortic aneurysm (AAA). Samples of peripheral venous blood were taken before induction of anaesthesia and then from a central venous line and the inferior mesenteric vein before, during, and after clamping of the aorta. Further specimens were taken from the central line at 2, 6 and 24 h after operation. Antioxidant concentration in the peripheral, central and inferior mesenteric blood were similar, indicating that anaesthesia and surgical dissection had no effect. Levels decreased significantly in central and inferior mesenteric blood during and after clamping, but returned to normal by 24 h. These results confirm ischaemia-reperfusion phenomena in AAA repair. 相似文献
75.
Wiener Richard L.; Rogers Melanie; Winter Ryan; Hurt Linda; Hackney Amy; Kadela Karen; Seib Hope; Rauch Shannon; Warren Laura; Morasco Ben 《Canadian Metallurgical Quarterly》2004,10(4):516
This article analyzes whether state-approved jury instructions adequately guide jury discretion in the penalty phase of first-degree murder trials. It examines Eighth Amendment jurisprudence regarding guided jury discretion, emphasizing the use of "empirical factors" to examine the quality of state-approved instructions. Psychological research and testimony on the topic of the comprehensibility of jury logical instructions are reviewed. Data from a recently completed simulation with 80 deliberating juries showed that current instructions do not adequately convey the concepts and processes essential to guiding penalty phase judgments. An additional simulation with 20 deliberating juries demonstrated that deliberation alone does not correct for jurors' errors in comprehension. The article concludes with recommendations for policy and future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
Skinner Ellen A.; Edge Kathleen; Altman Jeffrey; Sherwood Hayley 《Canadian Metallurgical Quarterly》2003,129(2):216
From analyzing 100 assessments of coping, the authors critiqued strategies and identified best practices for constructing category systems. From current systems, a list of 400 ways of coping was compiled. For constructing lower order categories, the authors concluded that confirmatory factor analysis should replace the 2 most common strategies (exploratory factor analysis and rational sorting). For higher order categories, they recommend that the 3 most common distinctions (problem- vs. emotion-focused, approach vs. avoidance, and cognitive vs. behavioral) no longer be used. Instead, the authors recommend hierarchical systems of action types (e.g., proximity seeking, accommodation). From analysis of 6 such systems, 13 potential core families of coping were identified. Future steps involve deciding how to organize these families, using their functional homogeneity and distinctiveness, and especially their links to adaptive processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
A total of 71 Staphylococcus aureus strains isolated from bovine mammary glands were identified and subtyped. The methods used to differentiate between the S. aureus isolates were the DNA polymorphism pattern after amplification with a Polymerase Chain Reaction using several primer combinations and phage typing. The DNA fingerprinting technique using RAPD, ERIC1R and ERIC primers proved to be useful in differentiating isolates of S. aureus. Differentiation of isolates using phage typing gave no additional information compared to the DNA technique. The outbreak of S. aureus in the herd studied was mainly caused by one S. aureus strain. Other strains were only found on three occasions, twice in subclinical infections and once from a case of clinical mastitis. In the latter case the dominant strain was isolated from a different quarter of the same cow. Four of the ten cows studied suffered from clinical mastitis. From those four cows, three remained infected with the same S. aureus strain despite antibiotic treatment. 相似文献
78.
SJ Thorpe D Walker P Arosio A Heath JD Cook M Worwood 《Canadian Metallurgical Quarterly》1997,43(9):1582-1587
A recombinant L ferritin preparation, lyophilized in ampoules and designated 94/572, was evaluated by 18 laboratories in 9 countries for its suitability as an International Standard (IS). The preparation was assayed in a wide range of in-house and commercial immunoassays against the 2nd IS for ferritin (of spleen origin; 80/578). The immunological reactivity of the recombinant material was similar to that of the 2nd IS for ferritin in the majority of assays and demonstrated adequate stability in accelerated degradation studies. On the basis of the results presented here, the WHO Expert Committee on Biological Standardization established 94/572 as the 3rd IS for ferritin, recombinant. 相似文献
79.
Gisela Epple Hope Niblick Stanley Lewis L. Dale Nolte Dan L. Campbell J. Russell Mason 《Journal of chemical ecology》1996,22(5):1013-1025
Essential oils from coniferous trees contain secondary metabolites that act as feeding deterrents for a number of herbivorous mammals. We investigated effects of pine needle oil on feeding and other behaviors of herbivorous plains pocket gophers. In experiment l, pocket gophers were offered sweet potato from single feeding stations placed in home cages of individually housed animals. Stations contained either a scent dispenser with pine needle oil or mineral oil. Subjects removed significantly less food from stations scented with pine needle oil. Experiment 2 was performed to investigate neophobic responses to odors.d-Pulegone, presented under conditions identical to those used in experiment l, did not reduce food removal compared to mineral oil. In experiment 3 pocket gophers were observed in a maze consisting of a start box connected to two goal boxes by tunnels. One goal was scented with pine needle oil, the second with mineral oil. Subjects entered goals scented with pine needle oil significantly less frequently than goals scented with mineral oil and spent less time there. They performed all recorded behaviors at lower frequencies while located in pine-scented goals. In experiment 4 animals were introduced into a maze consisting of a start box from which two soil-packed tunnels could be entered. Embedded in the soil of one tunnel was a barrier of electrical cable that had been soaked in pine needle oil, the second tunnel contained a barrier of cable soaked in mineral oil. Pocket gophers gnawed significantly less insulation from cable treated with pine needle oil than from cable treated with mineral oil. Our results show that constituents in pine needle oil are aversive to plains pocket gophers. Under natural conditions they may function as feeding deterrents. Some of the compounds may be suitable repellents for control of pocket gopher damage. 相似文献
80.
Mary Thorpe Robert McCormick Chris Kubiak Patrick Carmichael 《Pedagogy, Culture & Society》2007,15(3):349-366
Computer-mediated conferencing has been adopted, particularly for purposes of online course provision, as a method that can deliver community. Widespread interest in a communities-of-practice approach within both informal and formal learning has strengthened perceptions of the value of creating a community online. A case study of asynchronous computer conferencing for the purposes of leadership development in schools is the focus for a study of the features and the discursive quality of the online interaction that occurred. Two analytical approaches are used: discourse analysis and social network analysis. These highlighted different aspects of the case, in terms of the role of peers versus the expert moderator (or 'hotseat guest'), the extent of readership versus contribution and the tone and content of the discussion. Evidence that contributors were learning from the interaction was identified and strong links with place-based communities of practice were also evident. Nevertheless, the online interaction could not be said to constitute a community or to be evidently developing in that direction. Its features as a network, where weak links were key to a sharing and knowledge-construction process, were more salient. Networks offer the potential for weak connections that have a particular value for connecting across dispersed practitioners and potentially bridging between communities of practice and other forms of organisation and groupings. 相似文献