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   6973篇
  免费   479篇
  国内免费   7篇
电工技术   81篇
综合类   7篇
化学工业   1796篇
金属工艺   131篇
机械仪表   134篇
建筑科学   297篇
矿业工程   15篇
能源动力   172篇
轻工业   1160篇
水利工程   74篇
石油天然气   34篇
无线电   400篇
一般工业技术   1096篇
冶金工业   1180篇
原子能技术   37篇
自动化技术   845篇
  2024年   12篇
  2023年   57篇
  2022年   127篇
  2021年   291篇
  2020年   171篇
  2019年   198篇
  2018年   236篇
  2017年   234篇
  2016年   266篇
  2015年   183篇
  2014年   260篇
  2013年   479篇
  2012年   378篇
  2011年   493篇
  2010年   352篇
  2009年   333篇
  2008年   347篇
  2007年   284篇
  2006年   275篇
  2005年   169篇
  2004年   193篇
  2003年   181篇
  2002年   146篇
  2001年   105篇
  2000年   104篇
  1999年   94篇
  1998年   208篇
  1997年   184篇
  1996年   139篇
  1995年   103篇
  1994年   79篇
  1993年   76篇
  1992年   59篇
  1991年   56篇
  1990年   61篇
  1989年   55篇
  1988年   44篇
  1987年   42篇
  1986年   35篇
  1985年   37篇
  1984年   44篇
  1983年   29篇
  1982年   33篇
  1981年   12篇
  1980年   28篇
  1979年   29篇
  1978年   22篇
  1977年   21篇
  1976年   26篇
  1975年   14篇
排序方式: 共有7459条查询结果,搜索用时 15 毫秒
1.
2.
A set of novel hydrazone derivatives were synthesized and analyzed for their biological activities. The compounds were tested for their inhibitory effect on the phosphorylating activity of the protein kinase CK2, and their antioxidant activity was also determined in three commonly used assays. The hydrazones were evaluated for their radical scavenging against the DPPH, ABTS and peroxyl radicals. Several compounds have been identified as good antioxidants as well as potent protein kinase CK2 inhibitors. Most hydrazones containing a 4-N(CH3)2 residue or perfluorinated phenyl rings showed high activity in the radical-scavenging assays and possess nanomolar IC50 values in the kinase assays.  相似文献   
3.
4.
Production and world consumption of spices are constantly increasing. Although the antimicrobial properties of some spices are well documented, their use in the agri-food industry is also responsible for microbial contamination and spoilage. Bacterial spores introduced by spices can withstand different preparation processes, particularly thermal treatments, leading to food alterations during storage. This review brings together data from the literature about the prevalence and concentrations of spore-forming bacteria in all commercially available spices. The sporeformers found in spices belong mainly to the genera Bacillus and Clostridium. Such contaminations are very common and sometimes reach high levels, as in pepper and turmeric. Bacillus licheniformis and Bacillus cereus are the most frequently detected species. Studying the harvesting, processing, and storage procedures for spices provides elements to explain why high prevalence and concentrations are observed. Spices are mostly produced in developing countries on small farms using traditional production methods. Spices become contaminated by bacterial spores in two main ways: by contact with soil during harvesting or drying, as for pepper, or by cross-contamination during the water-cooking step, as for turmeric. From these observations, we propose some recommendations. Different methods that can be used to eliminate bacterial spores from spices are presented indicating their efficiency and the limitations of their use.  相似文献   
5.
Osteosarcoma (OS) is a rare condition with very poor prognosis in a metastatic setting. Basic research has enabled a better understanding of OS pathogenesis and the discovery of new potential therapeutic targets. Phase I and II clinical trials are already ongoing, with some promising results for these patients. This article reviews OS pathogenesis and new potential therapeutic targets.  相似文献   
6.
Corynebacterium silvaticum is a newly identified animal pathogen of forest animals such as roe deer and wild boars. The species is closely related to the emerging human pathogen Corynebacterium ulcerans and the widely distributed animal pathogen Corynebacterium pseudotuberculosis. In this study, Corynebacterium silvaticum strain W25 was characterized with respect to its interaction with human cell lines. Microscopy, measurement of transepithelial electric resistance and cytotoxicity assays revealed detrimental effects of C. silvaticum to different human epithelial cell lines and to an invertebrate animal model, Galleria mellonella larvae, comparable to diphtheria toxin-secreting C. ulcerans. Furthermore, the results obtained may indicate a considerable zoonotic potential of this newly identified species.  相似文献   
7.
The aim of this exploratory study has been to investigate the fire properties and environmental aspects of different upholstery material combinations, mainly for domestic applications. An analysis of the sustainability and circularity of selected textiles, along with lifecycle assessment, is used to qualitatively evaluate materials from an environmental perspective. The cone calorimeter was the primary tool used to screen 20 different material combinations from a fire performance perspective. It was found that textile covers of conventional fibres such as wool, cotton and polyester, can be improved by blending them with fire resistant speciality fibres. A new three‐dimensional web structure has been examined as an alternative padding material, showing preliminary promising fire properties with regard to ignition time, heat release rates and smoke production.  相似文献   
8.
9.
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with...  相似文献   
10.
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