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   7280篇
  免费   303篇
  国内免费   7篇
电工技术   71篇
综合类   4篇
化学工业   1556篇
金属工艺   168篇
机械仪表   172篇
建筑科学   291篇
矿业工程   20篇
能源动力   383篇
轻工业   903篇
水利工程   43篇
石油天然气   37篇
无线电   337篇
一般工业技术   1103篇
冶金工业   1404篇
原子能技术   101篇
自动化技术   997篇
  2024年   24篇
  2023年   63篇
  2022年   134篇
  2021年   216篇
  2020年   161篇
  2019年   141篇
  2018年   251篇
  2017年   262篇
  2016年   278篇
  2015年   163篇
  2014年   343篇
  2013年   607篇
  2012年   313篇
  2011年   379篇
  2010年   351篇
  2009年   336篇
  2008年   268篇
  2007年   275篇
  2006年   212篇
  2005年   153篇
  2004年   161篇
  2003年   137篇
  2002年   116篇
  2001年   92篇
  2000年   95篇
  1999年   85篇
  1998年   451篇
  1997年   251篇
  1996年   182篇
  1995年   128篇
  1994年   95篇
  1993年   100篇
  1992年   43篇
  1991年   47篇
  1990年   40篇
  1989年   33篇
  1988年   40篇
  1987年   24篇
  1986年   23篇
  1985年   58篇
  1984年   38篇
  1983年   26篇
  1982年   26篇
  1981年   37篇
  1980年   32篇
  1979年   25篇
  1978年   18篇
  1977年   46篇
  1976年   86篇
  1974年   20篇
排序方式: 共有7590条查询结果,搜索用时 15 毫秒
1.
2.
3.
Alkyd resins are generally used in the production of printing inks. All industries look for alternative raw materials in the production of ink with the growing inclination toward using natural products. Resins forming the vehicle of the ink to be obtained from natural resources will provide benefits for the environment, nature, and living creatures. The aim of the study was to promote the use of natural resin in the ink system. Natural Pinus pinaster resin was added into vegetable and mineral oil-based solvents in pure form with alkyd resin in different amounts and ink varnishes of different combinations were prepared. Then, printing inks were produced from these varnishes in pure and hybrid form. Following the assessment of the rheological properties of the inks prepared, printing tests were conducted to assess the printing quality parameters. Ideal mixing ratios of the natural resins in the ink were determined for printability. The environmental importance and advantages of the use of natural resins were discussed. Recommendations were given in line with the results to encourage widespread use of natural resins in near future.  相似文献   
4.
5.
6.
7.
In this study, the relationship between stunning techniques and protein oxidation which are accepted as the main cause of food spoilage was investigated. For this purpose, the antioxidant status, in vivo myofibrillary protein (MP) oxidation and sensitivity, and postmortem oxidation (inducted with hydroxyl radical system) of rainbow trout (Oncorhynchus mykiss) fillets killed by hitting to head (T1), neck crushing (T2), and convulsion (T3) methods, were investigated. Statistically significant differences (p < .05) were found among all parameters examined and it was observed that the most stressing technique was the convulsion method. It was determined that in protein profiles myosin were influenced too much from stunning technique and in actin observed oxidation-induced reductions. Reductions in S-S and S-H were also found to be increased in carbonyl concentrations, but the most effective values in both processes were determined by the convulsive technique. Our results show that short-term stunning techniques (hitting to head, neck crushing) give better meat quality results in terms of O. mykiss welfare and low MP oxidation rates. In general, we can say that T3 group fillets are more sensitive to oxidative damage, while T1 and T2 groups give better results in maintaining meat quality with low MP oxidation rates.  相似文献   
8.
In this article we consider the performance of the 3.84 Mcpstime-division duplex (TDD) mode of UTRA (Universal TerrestrialRadio Access) network. We emphasize two of the radio resourcemanagement algorithms, handover and uplink power control, whoserole in the overall system performance is studied extensively.First, a handover algorithm used in WCDMA (Wideband Code DivisionMultiple Access) standard is considered in a TDD-mode operation.This gives rise to a careful setting of different handoverparameters, and the evaluation of the effects to the systemperformance. Secondly, the specified uplink power controlalgorithm is considered. Since it is based on several user-mademeasurements which may involve both random and systematic errors acareful study about the suitability of the power control scheme iscarried out.  相似文献   
9.
An increase in hydrogen evolution from the hydrogen-evolving enzyme in the actinomycete Frankia was recorded in the presence of nickel. Immunogold localisation analysis of the intracellular distribution of hydrogenase proteins indicated that they were evenly distributed in the membranes and cytosol of both hyphae and vesicles. In addition, molecular characterisation of the hydrogen-evolving enzyme at the proteomic level, using two-dimensional gel electrophoresis combined with mass spectrometry, confirmed that the Frankia hydrogen-evolving enzyme is similar to the cyanobacterial bidirectional hydrogenase of Anabena siamensis.  相似文献   
10.
K. M. Granstr  m 《Drying Technology》2003,21(7):1197-1214
This paper describes a novel method to measure emission from dryers. The method resolves the known difficulties caused by diffuse emissions, and also solves the problems associated with high moisture content of the drying medium. The basic idea is to use water vapor to determine the exhaust flow, while a dry ice trap is used both to preconcentrate emitted VOCs and to determine the moisture content of the drying medium.  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