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   63157篇
  免费   16010篇
  国内免费   24篇
电工技术   1171篇
综合类   61篇
化学工业   22216篇
金属工艺   970篇
机械仪表   1285篇
建筑科学   2927篇
矿业工程   145篇
能源动力   1277篇
轻工业   10478篇
水利工程   544篇
石油天然气   78篇
无线电   8584篇
一般工业技术   17249篇
冶金工业   3664篇
原子能技术   222篇
自动化技术   8320篇
  2023年   317篇
  2022年   330篇
  2021年   867篇
  2020年   1886篇
  2019年   3619篇
  2018年   3880篇
  2017年   4184篇
  2016年   4690篇
  2015年   4598篇
  2014年   4704篇
  2013年   6713篇
  2012年   3881篇
  2011年   3820篇
  2010年   3829篇
  2009年   3617篇
  2008年   3299篇
  2007年   3127篇
  2006年   2557篇
  2005年   2108篇
  2004年   2002篇
  2003年   1942篇
  2002年   1867篇
  2001年   1581篇
  2000年   1491篇
  1999年   849篇
  1998年   937篇
  1997年   710篇
  1996年   516篇
  1995年   388篇
  1994年   351篇
  1993年   319篇
  1992年   209篇
  1991年   180篇
  1990年   185篇
  1989年   156篇
  1988年   169篇
  1987年   132篇
  1986年   123篇
  1985年   227篇
  1984年   217篇
  1983年   145篇
  1982年   153篇
  1981年   175篇
  1980年   145篇
  1979年   131篇
  1978年   130篇
  1977年   125篇
  1976年   160篇
  1975年   116篇
  1974年   93篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Journal of Low Temperature Physics - This study modeled and investigated the magnetocaloric effect in Ni2MnGa Heusler alloy characterized by its magnetic entropy change (ΔSm) and its...  相似文献   
12.
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   
13.
Xanthohumol (XH) is an important prenylated flavonoid that is found within the inflorescence of Humulus lupulus L. (Hop plant). XH is an important ingredient in beer and is considered a significant bioactive agent due to its diverse medicinal applications, which include anti-inflammatory, antimicrobial, antioxidant, immunomodulatory, antiviral, antifungal, antigenotoxic, antiangiogenic, and antimalarial effects as well as strong anticancer activity towards various types of cancer cells. XH acts as a wide ranging chemopreventive and anticancer agent, and its isomer, 8-prenylnaringenin, is a phytoestrogen with strong estrogenic activity. The present review focuses on the bioactivity of XH on various types of cancers and its pharmacokinetics. In this paper, we first highlight, in brief, the history and use of hops and then the chemistry and structure–activity relationship of XH. Lastly, we focus on its prominent effects and mechanisms of action on various cancers and its possible use in cancer prevention and treatment. Considering the limited number of available reviews on this subject, our goal is to provide a complete and detailed understanding of the anticancer effects of XH against different cancers.  相似文献   
14.
Antibiotic resistance is a growing problem for public health and associated with increasing economic costs and mortality rates. Silver and silver-related compounds have been used for centuries due to their antimicrobial properties. In this work, we show that 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene silver(I) acetate/NHC*-Ag-OAc (SBC3) is a reversible, high affinity inhibitor of E. coli thioredoxin reductase (TrxR; Ki=10.8±1.2 nM). Minimal inhibition concentration (MIC) tests with different E. coli and P. aeruginosa strains demonstrated that SBC3 can efficiently inhibit bacterial cell growth, especially in combination with established antibiotics like gentamicin. Our results show that SBC3 is a promising antibiotic drug candidate targeting bacterial TrxR.  相似文献   
15.
Fischer-Tropsch synthesis of the CO2 in biogas aims at producing light hydrocarbons and increasing its calorific value for feeding into the grid. Fe catalysts with Mn and K as promoters are supposed to yield high amounts of light hydrocarbons. Using a Fe-Mn-K/MgO catalyst, a parameter screening and long-term experiments were carried out. The catalyst shows, within the examined range, the highest selectivity to C2–C4 hydrocarbons at 450 °C, 8 bar(a), and a gas hourly space velocity of 350 h−1. Calcination of the catalyst resulted in a significant drop of activity and an almost complete loss of selectivity to hydrocarbons. Admixture of steam to the reactant gas lowers the tendency to carbon deposition but also promotes the water-gas shift reaction and results in lower yields of hydrocarbons.  相似文献   
16.
17.
Neural Computing and Applications - This study presents the design of a tenth-order multiple feedback Chebyshev low-pass filter (MF-C-LPF). Component selection and gain calculation of filters are...  相似文献   
18.
19.
20.
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