首页 | 官方网站   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   731977篇
  免费   9035篇
  国内免费   1526篇
工业技术   742538篇
  2021年   6417篇
  2019年   6195篇
  2018年   14855篇
  2017年   15114篇
  2016年   13958篇
  2015年   7375篇
  2014年   12201篇
  2013年   32276篇
  2012年   20257篇
  2011年   29747篇
  2010年   24626篇
  2009年   26320篇
  2008年   26756篇
  2007年   27657篇
  2006年   19936篇
  2005年   19850篇
  2004年   18412篇
  2003年   17950篇
  2002年   16624篇
  2001年   15919篇
  2000年   15442篇
  1999年   15277篇
  1998年   35981篇
  1997年   25880篇
  1996年   19443篇
  1995年   15273篇
  1994年   13833篇
  1993年   13465篇
  1992年   10364篇
  1991年   10055篇
  1990年   9825篇
  1989年   9584篇
  1988年   9234篇
  1987年   8242篇
  1986年   7991篇
  1985年   9194篇
  1984年   8358篇
  1983年   7934篇
  1982年   7100篇
  1981年   7323篇
  1980年   6928篇
  1979年   7076篇
  1978年   6977篇
  1977年   7810篇
  1976年   9964篇
  1975年   6213篇
  1974年   5980篇
  1973年   6059篇
  1972年   5147篇
  1971年   4819篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
71.
Russian Engineering Research - Models based on regression analysis for predicting the operational efficiency of high-pressure roller crushers are considered. A systematized and structured...  相似文献   
72.
Journal of Machinery Manufacture and Reliability - The problem of calculating the reliability and fatigue life of machine parts by the fatigue failure under random changes in the actual and limit...  相似文献   
73.
74.
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   
75.
76.
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   
77.
Russian Engineering Research - The strategic efficiency of a project is defined. An approach to assessing the strategic efficiency of projects is outlined. This approach, incorporated in the State...  相似文献   
78.
79.
80.
ABSTRACT

Bacteriocin is a proteinaceous biomolecule produced by bacteria (both Gram-positive and Gram-negative) that exhibits antimicrobial activity against closely related species, and food-borne pathogens. It has recently gained importance and attracted the attention of several researchers looking to produce it from various substrates and bacterial strains. This ushers in a new era of food preservation where the use of bacteriocin in food products will be an alternative to chemical preservatives, and heat treatment which are understood to cause unwanted side effects, and reduce sensory and nutritional quality. However, this new market depends on the success of novel downstream separation schemes from various types of crude feedstocks which are both effective and economic. This review focuses on the downstream separation of bacteriocin from various sources using both conventional and novel techniques. Finally, recommendations for future interesting areas of research that need to be pursued are highlighted.  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-23

京公网安备 11010802026262号