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   2719篇
  免费   105篇
  国内免费   6篇
电工技术   16篇
综合类   3篇
化学工业   387篇
金属工艺   50篇
机械仪表   26篇
建筑科学   53篇
矿业工程   5篇
能源动力   68篇
轻工业   185篇
水利工程   8篇
石油天然气   8篇
无线电   319篇
一般工业技术   336篇
冶金工业   1087篇
原子能技术   13篇
自动化技术   266篇
  2024年   5篇
  2023年   36篇
  2022年   54篇
  2021年   99篇
  2020年   71篇
  2019年   86篇
  2018年   76篇
  2017年   75篇
  2016年   111篇
  2015年   56篇
  2014年   83篇
  2013年   113篇
  2012年   97篇
  2011年   105篇
  2010年   88篇
  2009年   72篇
  2008年   78篇
  2007年   52篇
  2006年   39篇
  2005年   44篇
  2004年   30篇
  2003年   29篇
  2002年   33篇
  2001年   27篇
  2000年   29篇
  1999年   50篇
  1998年   351篇
  1997年   207篇
  1996年   132篇
  1995年   90篇
  1994年   60篇
  1993年   69篇
  1992年   25篇
  1991年   24篇
  1990年   22篇
  1989年   20篇
  1988年   19篇
  1987年   19篇
  1986年   14篇
  1985年   20篇
  1984年   5篇
  1983年   9篇
  1982年   16篇
  1981年   8篇
  1980年   9篇
  1979年   8篇
  1978年   7篇
  1977年   23篇
  1976年   24篇
  1975年   3篇
排序方式: 共有2830条查询结果,搜索用时 15 毫秒
101.
Vector-borne diseases are among those most sensitive to climate because the ecology of vectors and the development rate of pathogens within them are highly dependent on environmental conditions. Bluetongue (BT), a recently emerged arboviral disease of ruminants in Europe, is often cited as an illustration of climate''s impact on disease emergence, although no study has yet tested this association. Here, we develop a framework to quantitatively evaluate the effects of climate on BT''s emergence in Europe by integrating high-resolution climate observations and model simulations within a mechanistic model of BT transmission risk. We demonstrate that a climate-driven model explains, in both space and time, many aspects of BT''s recent emergence and spread, including the 2006 BT outbreak in northwest Europe which occurred in the year of highest projected risk since at least 1960. Furthermore, the model provides mechanistic insight into BT''s emergence, suggesting that the drivers of emergence across Europe differ between the South and the North. Driven by simulated future climate from an ensemble of 11 regional climate models, the model projects increase in the future risk of BT emergence across most of Europe with uncertainty in rate but not in trend. The framework described here is adaptable and applicable to other diseases, where the link between climate and disease transmission risk can be quantified, permitting the evaluation of scale and uncertainty in climate change''s impact on the future of such diseases.  相似文献   
102.
This study is devoted to the analysis of the properties of continuous bamboo fiber (BF)-reinforced polyamide 11 (PA 11) composites. The SEM observations highlighted continuity between BFs and the polymeric matrix showing a high density of hydrogen bonds. The comparative calorimetric study of the matrix and its composites showed that the crystallinity of PA 11 was not modified by the presence of bamboo fibers. The physical aging observed in PA 11 is no more observed in composites due to physical interactions between PA 11 and BFs. The mechanical properties were investigated by tensile strength and dynamic mechanical analysis. The introduction of BFs enhanced Young's modulus of the matrix by a factor of 10. The presence of BFs also improved the storage shear modulus G′ over the whole temperature range. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47623.  相似文献   
103.
104.
This study has examined the dynamics (in terms of levels and serovar diversity) of Salmonella in the “dual litter environment” that occurs within a single shed as a result of a management practice common in Australia. The study also looked at the physical parameters of the litter (pH, moisture content, water activity and litter temperature) as a means of understanding the Salmonella dynamics in these litter environments. The Australian practice results in the brooder end of the shed having new litter each cycle while the grow-out end has re-used litter (a “dual litter environment”). Two farms that adopted this partial litter re-use practice were studied over one full broiler cycle each. Litter was sampled weekly for the levels (and serovars) of Salmonella during a farming cycle. There was a trend for lower levels of Salmonella (and a lower Salmonella serovar) diversity in the re-used litter environment as compared with the new litter environment. Of the physical parameters examined, it would appear that the lower water activity associated with the re-used litter may contribute to the Salmonella dynamics in the dual environment.  相似文献   
105.
106.
107.
108.
A hybrid of graphene and conducting polymer holds great potential as the active materials for high performance chemical sensor application. In this work, a thin hybrid film of reduced graphene oxide (RG-O) and poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated by means of vapor phase polymerization and explored as active material for chemical sensors. The chemical sensors based on hybrid film of RG-O and PEDOT are capable of detecting electrical signals caused by the absorption of trace levels of different analyte vapors with high sensitivity, selectivity and fast response.  相似文献   
109.
110.
Journal of Mechanical Science and Technology - In the present study, Electrically assisted (EA) stress relief annealing for automotive springs is experimentally investigated. A concept of EA stress...  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