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   1781篇
  免费   101篇
  国内免费   3篇
电工技术   17篇
综合类   1篇
化学工业   442篇
金属工艺   39篇
机械仪表   48篇
建筑科学   68篇
矿业工程   4篇
能源动力   75篇
轻工业   214篇
水利工程   15篇
石油天然气   6篇
武器工业   1篇
无线电   168篇
一般工业技术   324篇
冶金工业   75篇
原子能技术   12篇
自动化技术   376篇
  2024年   2篇
  2023年   28篇
  2022年   63篇
  2021年   79篇
  2020年   61篇
  2019年   67篇
  2018年   63篇
  2017年   59篇
  2016年   55篇
  2015年   62篇
  2014年   74篇
  2013年   148篇
  2012年   115篇
  2011年   157篇
  2010年   103篇
  2009年   88篇
  2008年   117篇
  2007年   77篇
  2006年   68篇
  2005年   49篇
  2004年   48篇
  2003年   51篇
  2002年   36篇
  2001年   22篇
  2000年   11篇
  1999年   8篇
  1998年   17篇
  1997年   15篇
  1996年   23篇
  1995年   15篇
  1994年   15篇
  1993年   14篇
  1992年   4篇
  1991年   7篇
  1990年   6篇
  1989年   2篇
  1988年   8篇
  1987年   6篇
  1985年   11篇
  1984年   3篇
  1983年   3篇
  1979年   3篇
  1977年   2篇
  1976年   4篇
  1975年   3篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
  1969年   1篇
  1911年   2篇
排序方式: 共有1885条查询结果,搜索用时 15 毫秒
61.
This article presents a study of the effect of drying methods on dyeing capacity of widespread European flora dyestuff plant materials. The natural colorants, derived from the selected plant materials, were applied on chemical pulp in order to examine their dyeability. In this work, three different drying methods were examined—the natural, the air-, and the freeze-drying method—in various conditions. The plant materials that were dried naturally show weak dyeing results in comparison with the air- and freeze-dried materials. Freeze drying significantly improved the dyeing capacity of dyestuff plant materials with high initial moisture content. On the other hand, air drying at low temperature and high relative humidity improved the dyeing capacity of plant materials with low initial moisture content.  相似文献   
62.
63.
Mango fruit has high commercial value; however, major postharvest losses are encountered throughout the supply chain due to postharvest diseases. These results lead to the search for natural fungicide for postharvest diseases control. The antifungal effects of five essential oils (thyme, clove, cinnamon, anise and vitex) were assessed by disc volatilisation method. Thyme oil vapours at 5 μL per Petriplate, and clove and cinnamon oil at 8 μL per Petriplate showed 100% growth inhibition of mango pathogens in vitro. GC/MS analysis of essential oil showed thymol (23.88), o‐cymol (23.88) and terpinolene (23.88) as the major constituents of thyme oil. Clove and cinnamon oils contain 3‐allyl‐2‐methoxyphenol (37.42%) and benzofuran 3‐methyl (17.97%), respectively. Thyme oil as a fumigant at 66.7 μL L?1 showed a significant (P < 0.05) inhibition on postharvest pathogens of mango fruits stored at 25 °C for 6 days. Results of our study suggest the possibility of using thyme oil as an alternate natural fungicide to manage postharvest diseases in mango.  相似文献   
64.
65.
Multimedia Tools and Applications - Robust tracking of moving objects is still an open problem in computer vision. The problem and its difficulty depend on many factors, which includes the...  相似文献   
66.
Data-set of monthly global solar irradiance covering periods of at least 20 years over selected stations in Nigeria have been utilised to investigate the sky optical conditions over the five major vegetation zones of the country. The monthly variation of the clearness index for the selected stations has been investigated. Results show that the clearness index has its minimum in August which indicates reduced insolation during the monsoon month of August and maximum around November, December and February which shows high insolation. Statistical analysis of the monthly clearness index which gives the percentage depletion by the sky of the incoming insolation and the subsequent characterisation of the sky conditions based on this were also done. The results show that cloudy sky conditions prevail in the rainforest and mangrove swamp zones (e.g. Lagos, KT=0.40) while clear sky conditions prevail in the Sudan and Sahel vegetation (e.g. Nguru KT=0.66) and Kano (KT=0.65).  相似文献   
67.
The territorial capital of regions is an important determinant of growth, but also of the impact of EU Cohesion Policy. First, because it can act as a filter, enhancing the impact of regional policies. Second, the latter can help building territorial capital which, in turn, will foster regional development. This work analyses the medium and long-run relationship between the territorial capital of EU NUTS 3 regions and Cohesion Policy using data from the programming period 2000–2006. Results point out complementarities between different territorial assets of regions and the impact of EU regional policy: Cohesion Policy effectiveness is higher when investments are focused on the assets complementary to those already abundant in the region.  相似文献   
68.
The cover image is based on the Research Article Modelling concentration gradients in fed-batch cultivations of E. coli - towards the flexible design of scale-down experiments by Emmanuel Anane et al., DOI: 10.1002/jctb.5798 .

  相似文献   

69.
In this paper, we deal with some magnetostatic models considered in vector potential formulations and solved by a Finite Element solver. In order to ensure the uniqueness of the solution, a gauge condition has to be imposed, and several possibilities occur. Moreover, the source term has to be correctly defined to ensure a physically admissible solution. We show the equivalence between some of these choices for several kinds of boundary conditions. Moreover, we highlight their characteristic behaviors on some numerical benchmarks to illustrate our theoretical results.  相似文献   
70.
Several conditions are proposed to check different robustness properties (ISS, iISS, IOSS and OSS) for generic nonlinear systems applying the weighted homogeneity concept (global or local). The advantages of this result are that, under some mild conditions, the system robustness can be established as a function of the degree of homogeneity.  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