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   602229篇
  免费   9242篇
  国内免费   1058篇
电工技术   10781篇
综合类   500篇
化学工业   98407篇
金属工艺   23985篇
机械仪表   19222篇
建筑科学   13709篇
矿业工程   4388篇
能源动力   15417篇
轻工业   52028篇
水利工程   7228篇
石油天然气   15111篇
武器工业   44篇
无线电   61774篇
一般工业技术   121621篇
冶金工业   102526篇
原子能技术   14850篇
自动化技术   50938篇
  2022年   4452篇
  2021年   6561篇
  2020年   4797篇
  2019年   6180篇
  2018年   10508篇
  2017年   10677篇
  2016年   11253篇
  2015年   7157篇
  2014年   11604篇
  2013年   28783篇
  2012年   17846篇
  2011年   23300篇
  2010年   18676篇
  2009年   20476篇
  2008年   20595篇
  2007年   20069篇
  2006年   17308篇
  2005年   15686篇
  2004年   14840篇
  2003年   14442篇
  2002年   13921篇
  2001年   13300篇
  2000年   12786篇
  1999年   12474篇
  1998年   29715篇
  1997年   21445篇
  1996年   16559篇
  1995年   12577篇
  1994年   11331篇
  1993年   11151篇
  1992年   8536篇
  1991年   8304篇
  1990年   8143篇
  1989年   7943篇
  1988年   7631篇
  1987年   6887篇
  1986年   6657篇
  1985年   7546篇
  1984年   6831篇
  1983年   6538篇
  1982年   5905篇
  1981年   6041篇
  1980年   5781篇
  1979年   5820篇
  1978年   5746篇
  1977年   6453篇
  1976年   8261篇
  1975年   5175篇
  1974年   4951篇
  1973年   5054篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
In this study, amaranth flour was used as an ingredient to prepare gluten-free cookies. The production process and attributes of amaranth cookies were characterised, and the potential use of amaranth flour as a functional ingredient was analysed. Cookies exhibited a non-uniform reddish brown colour and a cookie factor ratio of 4.5 ± 0.6. Storage studies indicated that after 3 weeks at room temperature cookies presented slight variations in the texture. Simulated gastrointestinal digestion of this product was able to release peptides capable of exerting potential antithrombotic and antihypertensive activities, IC50 values of 0.22 ± 0.04 and 0.23 ± 0.03 mg mL−1 protein, respectively. This work demonstrates for the first time that food made with amaranth flour exerts potential antithrombotic and antihypertensive activity. In conclusion, these amaranth cookies could be an alternative way of incorporating potentially health beneficial products for people who choose a conscious diet, including coeliac or vegan consumers.  相似文献   
83.
84.
In this paper, we present an aero‐structural model of a tethered swept wing for airborne wind energy generation. The carbon composite wing has neither fuselage nor actuated aerodynamic control surfaces and is controlled entirely from the ground using three separate tethers. The computational model is efficient enough to be used for weight optimisation at the initial design stage. The main load‐bearing wing component is a nontypical “D”‐shaped wing‐box, which is represented as a slender carbon composite shell and further idealised as a stack of two‐dimensional cross section models arranged along an anisotropic one‐dimensional beam model. This reduced 2+1D finite element model is then combined with a nonlinear vortex step method that determines the aerodynamic load. A bridle model is utilised to calculate the individual forces as a function of the aerodynamic load in the bridle lines that connect the main tether to the wing. The entire computational model is used to explore the influence of the bride on the D‐box structure. Considering a reference D‐box design along with a reference aerodynamic load case, the structural response is analysed for typical bridle configurations. Subsequently, an optimisation of the internal geometry and laminate fibre orientations is carried out using the structural computation models, for a fixed aerodynamic and bridle configuration. Aiming at a minimal weight of the wing structure, we find that for the typical load case of the system, an overall weight savings of approximately 20% can be achieved compared with the initial reference design.  相似文献   
85.
86.
87.
This study aimed to evaluate the physicochemical characteristics and sensory attributes of beef burgers with the addition of pea fibre as a partial substitute of meat or fat. Three formulations were prepared: control (CON) – similar to the commercial formulation; fibre/less meat (FLM)—5% meat reduction and addition of 1% pea fibre; fibre/less fat (FLF)—7% fat reduction and addition of 1% pea fibre. Non-significant differences were obtained for pH, colour parameters (L* and b*), texture profile, cooking loss and size reduction among formulations. Moreover, sensory analysis with consumers of beef burgers did not indicate differences among the formulations for all the analysed attributes. Therefore, pea fibre is a promising partial replacer for meat and fat in beef burgers due to the preservation of technological parameters and sensory acceptance.  相似文献   
88.
89.
Theoretical Foundations of Chemical Engineering - New research results, as well as those published earlier by the authors, on the synthesis of azo compounds based on nitroanilines obtained by the...  相似文献   
90.
In the future, hydrogen will be an important energy carrier and industrial raw material. Catalytic steam reforming of bio-oils is a promising and economically viable technology for hydrogen production. However, during the reforming process, the catalysts are rapidly deactivated due to coke formation and sintering. Thus, maintaining the activity and stability of catalysts is the key issue in this process. Optimized operation conditions could extend the catalyst lifetime by affecting the coke morphology or promoting coke gasification. This article summarizes the recent developments in the field of catalytic steam reforming of bio-oils, focusing on the operation conditions, the properties of the catalysts, and the effects of the catalyst supports. The expected insights into the catalytic steam reforming of bio-oils will provide further guidance for hydrogen production from bio-oils.  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