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   6389篇
  免费   487篇
  国内免费   11篇
电工技术   58篇
综合类   10篇
化学工业   2827篇
金属工艺   78篇
机械仪表   86篇
建筑科学   263篇
矿业工程   35篇
能源动力   160篇
轻工业   1130篇
水利工程   41篇
石油天然气   35篇
无线电   261篇
一般工业技术   937篇
冶金工业   321篇
原子能技术   15篇
自动化技术   630篇
  2024年   16篇
  2023年   112篇
  2022年   669篇
  2021年   775篇
  2020年   231篇
  2019年   211篇
  2018年   254篇
  2017年   207篇
  2016年   263篇
  2015年   224篇
  2014年   271篇
  2013年   449篇
  2012年   374篇
  2011年   412篇
  2010年   276篇
  2009年   274篇
  2008年   276篇
  2007年   243篇
  2006年   214篇
  2005年   152篇
  2004年   139篇
  2003年   113篇
  2002年   99篇
  2001年   55篇
  2000年   47篇
  1999年   55篇
  1998年   35篇
  1997年   42篇
  1996年   43篇
  1995年   35篇
  1994年   36篇
  1993年   31篇
  1992年   27篇
  1991年   16篇
  1990年   23篇
  1989年   11篇
  1988年   18篇
  1987年   14篇
  1986年   7篇
  1985年   18篇
  1984年   16篇
  1983年   17篇
  1982年   6篇
  1981年   11篇
  1980年   11篇
  1979年   9篇
  1977年   7篇
  1976年   5篇
  1974年   4篇
  1966年   5篇
排序方式: 共有6887条查询结果,搜索用时 15 毫秒
181.
182.
More than two hundred years after its discovery, lactate still remains an intriguing molecule. Considered for a long time as a waste product of metabolism and the culprit behind muscular fatigue, it was then recognized as an important fuel for many cells. In particular, in the nervous system, it has been proposed that lactate, released by astrocytes in response to neuronal activation, is taken up by neurons, oxidized to pyruvate and used for synthesizing acetyl-CoA to be used for the tricarboxylic acid cycle. More recently, in addition to this metabolic role, the discovery of a specific receptor prompted a reconsideration of its role, and lactate is now seen as a sort of hormone, even involved in processes as complex as memory formation and neuroprotection. As a matter of fact, exercise offers many benefits for our organisms, and seems to delay brain aging and neurodegeneration. Now, exercise induces the production and release of lactate into the blood which can reach the liver, the heart, and also the brain. Can lactate be a beneficial molecule produced during exercise, and offer neuroprotection? In this review, we summarize what we have known on lactate, discussing the roles that have been attributed to this molecule over time.  相似文献   
183.
The combination of an antifungal agent and drug carrier with adjunctive antimicrobial properties represents novel strategy of complex therapy in pharmaceutical technology. The goal of this study was to investigate the unmodified and ion cross-linked chitosan’s influence on anti-Candida activity of clotrimazole used as a model drug in hydrogels. It was particularly crucial to explore whether the chitosans’ structure modification by β-glycerophosphate altered its antifungal properties. Antifungal studies (performed by plate diffusion method according to CLSI reference protocol) revealed that hydrogels obtained with chitosan/β-glycerophosphate displayed lower anti-Candida effect, probably as a result of weakened polycationic properties of chitosan in the presence of ion cross-linker. Designed chitosan hydrogels with clotrimazole were found to be more efficient against tested Candida strains and showed more favorable drug release profile compared to commercially available product. These observations indicate that novel chitosan formulations may be considered as promising semi-solid delivery system of clotrimazole.  相似文献   
184.
We present experimental and theoretical comparisons of the coarsening rate for the MX (X?=?C, N or C?+?N) precipitate in five different tool steel grades produced by Powder Metallurgy (PM). The alloys contain different amounts of nitrogen and carbon; ranging from high carbon/low nitrogen to high nitrogen/low carbon. Common for the grades is a high amount of precipitate forming alloying elements resulting in a high fraction of hard phase. Experimentally we have found out that the nitrogen rich precipitates coarsen slower, both for higher and lower carbon content, than the carbon rich precipitates. Coarsening simulations are performed utilizing the DICTRA software and an agreement between calculations and measurements can be concluded.  相似文献   
185.
186.
187.
In this study, a fortified pancake with all parts of pomegranate as juice and by-products, added in the formulation, was designed. The influence of pomegranate addition on nutritional and sensory quality of pancake, as well as on its shelf-life, was assessed. As one would expect, the enrichment significantly improved the pancake polyphenolic content as compared to the control sample. Surprisingly, pomegranate addition did not affect its sensory quality. In fact, the enriched pancake was greatly appreciated from the sensory point of view. Results also suggested that the addition of pomegranate improved the glycemic index (GI). In fact, while a value of GI equal to 100 was obtained for the control sample, a GI of 71 was measured for the fortified sample. In terms of shelf-life, 30 days were obtained for the enriched pancake, whereas the control sample remained acceptable for about 26 days.  相似文献   
188.
Food Science and Biotechnology - The objective of this study was to obtain the in vitro cultures of Boletus badius under controlled conditions and investigate the release of indole compounds and...  相似文献   
189.
Integrated coal Gasification Combined Cycle (IGCC) is the most advanced technology for coal‐fired power generation. The two‐stage entrained flow gasification process allows for the use of a wide range of coal, as long as the gasification temperature is above the ash melting point of a used fuel. In this gasification technology, lignite, which often has a low ash melting point, can be preferably utilized. However, ash fluidity is also another importance, because the behaviour of molten slag can diminish a stable ash discharge from a gasifier. As the eligibility of coal ash properties is a considerable factor, water physically and chemically kept in lignite (30 – 60% in mass) attributes to deteriorating gasification efficiency, because it causes significant heat loss and increasing oxygen consumption. Developing a thermal evaporative lignite drying method will be a necessary attempt to apply lignite to the coal gasification process. For those preceded objectives, coal and ash properties and drying characteristics of several grades of Polish lignite, extracted from Belchatow and Turow deposits, have been experimentally investigated in a preliminary study evaluating the applicability and consideration for its utilization in state‐of‐the‐art clean coal technology, IGCC. This paper particularly discusses the eligibility of Polish lignite from the perspective of the fusibility and fluidity of ash melts and the fundamental drying kinetics of lignite in superheated steam in the light of water removal. The viscosity of ash melts is measured at high temperature up to 1700 °C. In the drying tests, the significant influence of structural issues, because of the provenance and origin of lignite on the drying characteristics, was found by applying the method of sensitivity analysis of physical propensity. This paper concludes that the investigated Polish lignite has characteristics favourable for utilization in IGCC technology, once the precautions related to its high moisture have been carefully addressed. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
190.
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