全文获取类型
收费全文 | 3002篇 |
免费 | 91篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 24篇 |
化学工业 | 162篇 |
金属工艺 | 8篇 |
机械仪表 | 23篇 |
建筑科学 | 31篇 |
能源动力 | 20篇 |
轻工业 | 301篇 |
水利工程 | 3篇 |
石油天然气 | 5篇 |
无线电 | 138篇 |
一般工业技术 | 189篇 |
冶金工业 | 2041篇 |
原子能技术 | 16篇 |
自动化技术 | 135篇 |
出版年
2022年 | 10篇 |
2021年 | 9篇 |
2019年 | 17篇 |
2018年 | 16篇 |
2017年 | 11篇 |
2016年 | 23篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 58篇 |
2012年 | 36篇 |
2011年 | 47篇 |
2010年 | 21篇 |
2009年 | 29篇 |
2008年 | 49篇 |
2007年 | 54篇 |
2006年 | 55篇 |
2005年 | 54篇 |
2004年 | 62篇 |
2003年 | 50篇 |
2002年 | 51篇 |
2001年 | 33篇 |
2000年 | 25篇 |
1999年 | 75篇 |
1998年 | 627篇 |
1997年 | 341篇 |
1996年 | 254篇 |
1995年 | 137篇 |
1994年 | 117篇 |
1993年 | 172篇 |
1992年 | 19篇 |
1991年 | 37篇 |
1990年 | 29篇 |
1989年 | 43篇 |
1988年 | 28篇 |
1987年 | 30篇 |
1986年 | 30篇 |
1985年 | 23篇 |
1984年 | 17篇 |
1983年 | 20篇 |
1982年 | 19篇 |
1981年 | 23篇 |
1980年 | 38篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 52篇 |
1976年 | 119篇 |
1975年 | 11篇 |
1974年 | 12篇 |
1971年 | 8篇 |
1970年 | 10篇 |
排序方式: 共有3096条查询结果,搜索用时 15 毫秒
91.
Ewen R Brierley Peter J Wilde Akiko Onishi Paul S Hughes William J Simpson David C Clark 《Journal of the science of food and agriculture》1996,70(4):531-537
The effect of ethanol on the foaming properties of beer protein fractions was studied using a microconductivity method and nitrogen gas to generate the foam. Increasing the ethanol concentration resulted in a decrease in foam stability. Interfacial studies including thin film drainage and dilational elasticity measurements indicated that ethanol reduced the rigidity of the adsorbed protein layer resulting in accelerated drainage from the foam lamellae and increased probability of film rupture. These results conflict with data from the Rudin method (using nitrogen gas to generate the foam) which indicate that, at low concentration, ethanol improves foam stability. These apparently conflicting results may be explained by the foam positive effects of a decline in bubble size and increase in bulk viscosity observed for the Rudin method, contrasted with the negative influence of a reduction in surface viscosity observed for the microconductivity foam assessment method. 相似文献
92.
William T. Simpson 《Drying Technology》2013,31(2):235-264
ABSTRACT This paper reviews the technology of wood drying and recent developments in the field. The importance of drying is reviewed first. Then the fundamentals of wood properties as they relate to drying are discussed, including how water is held in wood, how it moves through wood, and how drying stresses that lead to drying defects develop. Traditional drying technology for lumber, veneer, and heavy timbers is then presented. With this background, the discussion moves to recent developments in drying technology that have been implemented commercially, such as high-temperature drying, low-temperature drying, continuously rising temperature drying, vacuum drying, and advances in process control. Finally, a discussion is presented on drying technology of the future. This topic describes processes that offer potential improvements in drying technology, but are still in the research and development stage. 相似文献
93.
Using a sensitive direct gas analysis technique, an attempt was made to detect hydrogen evolution from copper corroding in neutral oxygen free chloride solutions. No hydrogen was detected at evolution rates 3 orders of magnitude lower than those reported for copper in pure water. 相似文献
94.
Pulse crops are cool season, annually grown legume crops, which are harvested for their seeds. They are invaluable agricultural commodities which are produced and imported by many regions of the world. Pulse seeds are a valuable source of dietary protein, carbohydrates, fiber and an important source of essential vitamins and minerals. Their nutritional characteristics have been associated with a reduction in the incidence of various cancers, HDL cholesterol, type-2 diabetes and heart disease. Pulses also contain protein and non-protein antinutritional factors, which may cause deleterious effects on the host when the seeds or processed seeds are consumed raw. Conversely, recent studies have demonstrated that protein antinutritional compounds such as lectins, protease inhibitors and the non-antinutritional component, angiotensin I-converting enzyme (ACE) inhibitor may have beneficial properties. Lectins have been associated with reducing certain forms of cancer, activating innate defense mechanisms and managing obesity. Protease inhibitors such as trypsin and chymotrypsin inhibitors have been demonstrated to reduce the incidence of certain cancers and demonstrate potent anti-inflammatory properties. Angiotensin I-converting enzyme (ACE) inhibitor has been associated with a reduction in hypertension. 相似文献
95.
Schwebel David C.; Swart Dehran; Simpson Jennifer; Hui Siu-kuen Azor; Hobe Phumla 《Canadian Metallurgical Quarterly》2009,28(4):493
Objective: Unintentional injury rates in low- and middle-income countries are up to 50 times higher than high-income nations. In South Africa, kerosene (paraffin) is a leading cause of poisoning and burns, particularly in low-income communities where it serves as a primary fuel for light, cooking, and heating. This study tested a community-based intervention to reduce kerosene-related injury risk. The intervention used a train-the-trainers model, whereby expert trainers train local paraprofessionals, who in turn deliver educational materials to community residents. The intervention was theory-driven, pragmatically motivated, and culturally sensitive. Design: Prospective quasi-experimental intervention design with nonequivalent case versus control groups. Main Outcome Measures: Three primary outcome measures were considered: self-reported knowledge of kerosene safety, observed practice of safe kerosene use, and self-reported recognition of risk for kerosene-related injury. Results: ANOVA models suggest a large and significant increase in self-reported kerosene-related knowledge in the intervention community compared to the control community. There were smaller, but statistically significant changes, in kerosene-related safety practices and recognition of kerosene injury risk in the intervention community compared to the control community. Conclusion: The intervention was successful. A train-the-trainers model might be an effective educational tool to reduce kerosene-related injury risk in low-income communities within low- and middle-income countries. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
Judith E. Innes David M. Simpson 《Journal of the American Planning Association. American Planning Association》2013,79(2):230-234
Geographic information systems have finally arrived in state and local governments and, with them, an extraordinary opportunity for planning. Many groups with differing agendas are competing to define this new technology, what it will do, and who will use it. It is by no means certain that planners will do well in this competition. This article mines the literature on technological innovation and concludes that planners must understand GIS as a socially constructed technology, including not just hardware and software but also the practices, laws, organizational arrangements, and knowledge that are necessary for its use. The article recommends a strategic approach to GIS implementation that involves both human and technical systems. 相似文献
97.
Stephen W. Rothwell Evelyn Sawyer Jennifer Dorsey William S. Flournoy Timothy Settle David Simpson Gary Cadd Paul Janmey Charles White Kathleen A. Szabo 《Journal of materials science. Materials in medicine》2009,20(10):2155-2166
We investigated the inflammatory response in pigs exposed to salmon fibrinogen/thrombin dressings. Animals were exposed to
the material in 3 ways: (a) thrombin and fibrinogen were injected intravenously, (b) dual full-thickness skin lesions were
surgically created on the dorsal aspect of the swine and treated with the fibrinogen/thrombin bandage and a commercial bandage
or (c) a fibrinogen/thrombin bandage was inserted through an abdominal incision into the peritoneal cavity. Blood was collected
twice weekly and animals were sacrificed at 7, 10 or 28 days. Animals in the 28-day dermal lesion group were given an injection
of salmon fibrinogen/thrombin at the 10 day point to simulate a second bandage application. The immune response manifested
itself as induction of germinal centers in mesenteric lymph nodes and in the white pulp of the spleen. Examination of the
histology of the skin and organs showed a cellular inflammatory response with granulation tissue and signs of edema that resolved
by the 28-day stage. Antibodies reactive to salmon and human thrombin and fibrinogen were detected, but fibrinogen levels
and coagulation processes were not affected. In conclusion, animals treated with salmon fibrinogen/thrombin bandages demonstrated
a smooth recovery course in terms of both tissue healing and the immune response without adverse effects from the exposure
to the fish proteins. 相似文献
98.
Few psychological studies, if any, can claim a legacy as imposing as the obedience studies of Stanley Milgram. Their impact was of notable consequence in the separate spheres of research ethics, research design, and theory in psychology, and they changed the ways that psychologists conceptualize and conduct their research. The authors discuss the legacy of these studies, especially as they effected dramatic changes in the fields of personality and social psychology. The article concludes with a discussion of what psychological science has lost in the aftermath of Milgram--high impact studies--and the salience that such research has in illuminating the most significant problems of our society, studies that could produce great human benefits. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
99.
In this study it is demonstrated that, with respect to model formulation, the number of linear and nonlinear equations involved in water distribution networks can be reduced to the number of closed simple loops. Regarding the optimization technique, a discrete state transition algorithm (STA) is introduced to solve several cases of water distribution networks. Firstly, the focus is on a parametric study of the ‘restoration probability and risk probability’ in the dynamic STA. To deal effectively with head pressure constraints, the influence is then investigated of the penalty coefficient and search enforcement on the performance of the algorithm. Based on the experience gained from training the Two-Loop network problem, a discrete STA has successfully achieved the best known solutions for the Hanoi, triple Hanoi and New York network problems. 相似文献
100.
Ward Ryan D.; Kellendonk Christoph; Simpson Eleanor H.; Lipatova Olga; Drew Michael R.; Fairhurst Stephen; Kandel Eric R.; Balsam Peter D. 《Canadian Metallurgical Quarterly》2009,123(4):720
Increased striatal dopamine D2 receptor activity is thought to contribute to the pathophysiology of schizophrenia. To model this condition in mice, Kellendonk et al. (2006) generated transgenic mice that selectively overexpress the D2 receptor in striatum (D2OE). Drew et al. (2007) reported that D2OE mice display deficits in interval timing and motivation. The present study further explored the impaired timing in D2OE mice. Experiment 1 assessed the role of motivation in producing timing deficits in the peak procedure and found that performance in D2OE mice was improved by increasing motivation. In addition, performance was impaired in control mice when motivation was decreased. In Experiment 2, we found that D2OE mice have no timing impairment when tested using the bisection task, a procedure in which the measure of timing performance is less influenced by motivation to respond. In Experiment 3, we also used the bisection task and found selective impairment in timing of long durations in D2OE mice. These results suggest that striatal D2 overexpression impairs timing by decreasing motivation and through its impact on working memory and/or sustained attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献