首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3222篇
  免费   82篇
  国内免费   4篇
电工技术   90篇
综合类   10篇
化学工业   655篇
金属工艺   86篇
机械仪表   57篇
建筑科学   160篇
矿业工程   14篇
能源动力   36篇
轻工业   340篇
水利工程   12篇
石油天然气   7篇
无线电   227篇
一般工业技术   461篇
冶金工业   855篇
原子能技术   18篇
自动化技术   280篇
  2020年   36篇
  2019年   38篇
  2018年   37篇
  2017年   36篇
  2016年   58篇
  2015年   42篇
  2014年   48篇
  2013年   151篇
  2012年   73篇
  2011年   102篇
  2010年   75篇
  2009年   88篇
  2008年   92篇
  2007年   102篇
  2006年   90篇
  2005年   89篇
  2004年   75篇
  2003年   77篇
  2002年   78篇
  2001年   49篇
  2000年   52篇
  1999年   70篇
  1998年   96篇
  1997年   92篇
  1996年   64篇
  1995年   48篇
  1994年   60篇
  1993年   64篇
  1992年   51篇
  1991年   37篇
  1990年   38篇
  1989年   52篇
  1988年   42篇
  1987年   34篇
  1986年   33篇
  1985年   50篇
  1984年   57篇
  1983年   55篇
  1982年   41篇
  1981年   42篇
  1980年   45篇
  1979年   38篇
  1978年   46篇
  1977年   41篇
  1976年   61篇
  1975年   40篇
  1974年   32篇
  1972年   37篇
  1971年   35篇
  1966年   33篇
排序方式: 共有3308条查询结果,搜索用时 15 毫秒
81.
82.
Nutritional research is currently entering the field of personalized nutrition, to a large extent driven by major technological breakthroughs in analytical sciences and biocomputing. An efficient launching of the personalized approach depends on the ability of researchers to comprehensively monitor and characterize interindividual variability in the activity of the human gastrointestinal tract. This information is currently not available in such a form. This review therefore aims at identifying and discussing published data, providing evidence on interindividual variability in the processing of the major nutrients, i.e., protein, fat, carbohydrates, vitamins, and minerals, along the gastrointestinal tract, including oral processing, intestinal digestion, and absorption. Although interindividual variability is not a primary endpoint of most studies identified, a significant number of publications provides a wealth of information on this topic for each category of nutrients. This knowledge remains fragmented, however, and understanding the clinical relevance of most of the interindividual responses to food ingestion described in this review remains unclear. In that regard, this review has identified a gap and sets the base for future research addressing the issue of the interindividual variability in the response of the human organism to the ingestion of foods.  相似文献   
83.
The growth of vapor bubbles is studied numerically in a microchannel with asymmetric surface features. The channel design is chosen such that evaporation results in vapor bubbles growing only along a predefined direction. The principle relies on capillary forces and the pinning/depinning of three-phase contact lines at sharp edges of the wall geometry. Analytical expressions are derived predicting the direction of bubble growth and allowing to assess the robustness of a specific channel geometry in terms of supporting unidirectional bubble growth. From these expressions design rules for microchannels incorporating geometrical parameters and the wall contact angle of the liquid phase can be derived. The numerical calculations are performed based on an extended Volume-of-Fluid method accounting for phase change. The results confirm that under specific conditions, vapor bubbles only expand in one direction, thereby corroborating the analytical model. The presented concept may find applications in designing microchannels for stabilized flow boiling or micropumps/-actuators relying on phase change.  相似文献   
84.
The non-destructive assessment of cracks in concrete is a common task for which non-destructive evaluation solutions have been published. Primarily, these tests have been carried out on artificial cracks that have been created by using notches instead of natural cracks. This study evaluates a procedure designed to create reproducible and controlled cracks in concrete. The procedure is based on using expanding mortar in a series of blind holes. This is done in combination with carefully aligned reinforcement to guide the direction of the crack development. The depth of the crack is also controlled by reinforcement. Crack depth varies statistically in the range of the maximum aggregate size (16 mm) used for concrete.  相似文献   
85.
86.
87.
This study develops a research method of assessing people's satisfaction with housing. Instead of the old approaches which consider in fragmented ways the characteristics of the dwelling, or the neighborhood, or the social environment, the author proposes a systems approach in which various interdependent factors are studied in relation to one another. Using the techniques developed, the relative satisfaction of tenants in public housing projects in certain areas of Canada is identified, analyzed, and discussed.  相似文献   
88.
The UK's Private Finance Initiative market is predicted to rise to over £8 billion a year and there are indications of growing opportunities. PFI creates a long‐term income stream and provides valuable opportunities for portfolio diversification. PFI has evolved at a fast pace and the momentum is set to continue. However, there are major challenges facing construction organisations. These include the lack of PFI experts, longer negotiation periods and tight time schedules to deliver large‐scale schemes, high levels of investment and risks involved and limited knowledge transfer between PFI projects. Concerns over the level of knowledge sharing have prompted the development and evaluation of a Knowledge Transfer Framework that encourages construction organisations to transfer PFI knowledge between projects. It achieves this by building on a questionnaire survey of PFI clients and construction companies, case studies of companies involved in PFI, and research workshops to validate the framework developed.  相似文献   
89.
When We Build Again. A Bournville Village Trust Research Publication. George Allen &; Unwin, Ltd., London, 1941. Pp. xii (16), 138.

Report Relative to Postwar Reconstruction in the City, Prepared by Improvements and Town Planning Committee, published by The Corporation of London, 1944, pp. 66 plus maps and photographs.

The Economic Status of the New York Metropolitan Region in 1944, by The Regional Plan Association, Inc., New York, 1944, xx, 91 pp.  相似文献   
90.
Chitin and its deacetylated derivative, chitosan, are nontoxic, antibacterial, biodegradable, and biocompatible biopolymers. Due to these properties, they are widely used for biomedical applications such as scaffolds for tissue engineering, wound dressings, separation membranes and antibacterial coatings. Unfortunately, there is still a lack of suitable solvent systems for the direct processing of chitin, e.g., into films and coatings. Such solvents must be nontoxic, noncorrosive, nondegrading, and allow for high chitin concentrations. Here, the potential of designed ionic liquids (IL) as solvents for chitin is outlined. Phosphonium‐ and imidazolium‐based ILs are synthesized, characterized and the influence of the cation on the solution process has been evaluated. It is shown that particularly imidazolium carboxylate‐based ILs are appropriate solvents for chitin and are suitable for the production of foils and coatings on both fabrics and foams.

  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号