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   636167篇
  免费   7651篇
  国内免费   1741篇
电工技术   11708篇
综合类   574篇
化学工业   98254篇
金属工艺   30094篇
机械仪表   21995篇
建筑科学   14021篇
矿业工程   4724篇
能源动力   15854篇
轻工业   48105篇
水利工程   7783篇
石油天然气   16069篇
武器工业   39篇
无线电   66871篇
一般工业技术   134603篇
冶金工业   103929篇
原子能技术   15449篇
自动化技术   55487篇
  2021年   5708篇
  2020年   4212篇
  2019年   5514篇
  2018年   14142篇
  2017年   14442篇
  2016年   13101篇
  2015年   6683篇
  2014年   10884篇
  2013年   27936篇
  2012年   18176篇
  2011年   26970篇
  2010年   22445篇
  2009年   23758篇
  2008年   24113篇
  2007年   25159篇
  2006年   17338篇
  2005年   17563篇
  2004年   16102篇
  2003年   15560篇
  2002年   14518篇
  2001年   13697篇
  2000年   13164篇
  1999年   12797篇
  1998年   29261篇
  1997年   21339篇
  1996年   16781篇
  1995年   12757篇
  1994年   11452篇
  1993年   11208篇
  1992年   8756篇
  1991年   8510篇
  1990年   8342篇
  1989年   8079篇
  1988年   7734篇
  1987年   7020篇
  1986年   6731篇
  1985年   7613篇
  1984年   6895篇
  1983年   6619篇
  1982年   5951篇
  1981年   6069篇
  1980年   5843篇
  1979年   5915篇
  1978年   5824篇
  1977年   6445篇
  1976年   8092篇
  1975年   5270篇
  1974年   5045篇
  1973年   5132篇
  1972年   4419篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
71.
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   
72.
73.
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   
74.
75.
76.
77.
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   
78.
79.
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   
80.
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