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   850篇
  免费   26篇
  国内免费   2篇
电工技术   7篇
综合类   1篇
化学工业   116篇
金属工艺   24篇
机械仪表   19篇
建筑科学   29篇
矿业工程   8篇
能源动力   12篇
轻工业   102篇
水利工程   10篇
无线电   40篇
一般工业技术   114篇
冶金工业   280篇
原子能技术   5篇
自动化技术   111篇
  2023年   8篇
  2022年   12篇
  2021年   28篇
  2020年   20篇
  2019年   10篇
  2018年   16篇
  2017年   11篇
  2016年   24篇
  2015年   16篇
  2014年   29篇
  2013年   49篇
  2012年   37篇
  2011年   45篇
  2010年   18篇
  2009年   34篇
  2008年   42篇
  2007年   41篇
  2006年   26篇
  2005年   24篇
  2004年   18篇
  2003年   20篇
  2002年   14篇
  2001年   17篇
  2000年   19篇
  1999年   17篇
  1998年   44篇
  1997年   33篇
  1996年   17篇
  1995年   21篇
  1994年   12篇
  1993年   19篇
  1992年   8篇
  1991年   8篇
  1990年   8篇
  1989年   8篇
  1988年   6篇
  1987年   8篇
  1986年   7篇
  1985年   10篇
  1984年   5篇
  1983年   6篇
  1980年   3篇
  1979年   4篇
  1978年   4篇
  1977年   9篇
  1976年   9篇
  1974年   5篇
  1973年   4篇
  1972年   4篇
  1963年   3篇
排序方式: 共有878条查询结果,搜索用时 0 毫秒
81.
82.
Aging causes a progressive decline in the structure and function of organs. With advancing age, an accumulation of senescent endothelial cells (ECs) contributes to the risk of developing vascular dysfunction and cardiovascular diseases, including hypertension, diabetes, atherosclerosis, and neurodegeneration. Senescent ECs undergo phenotypic changes that alter the pattern of expressed proteins, as well as their morphologies and functions, and have been linked to vascular impairments, such as aortic stiffness, enhanced inflammation, and dysregulated vascular tone. Numerous molecules and pathways, including sirtuins, Klotho, RAAS, IGFBP, NRF2, and mTOR, have been implicated in promoting EC senescence. This review summarizes the molecular players and signaling pathways driving EC senescence and identifies targets with possible therapeutic value in age-related vascular diseases.  相似文献   
83.
Participants made judgments about the relative salience of category exemplars (e.g., fruit: apple or grape) or parts (e.g., plane: wings or seats). Mildly affected Alzheimer's disease (AD) patients were as accurate but slower than normal controls, and their response times increased more for related (e.g., apple, grape, or fig) than unrelated (e.g., apple, gym, bandit) choices as the number of alternatives was increased from 2 to 3. Performance (accuracy and response times) of moderate-severely affected patients was poorer still, but number of distractors and relatedness did not interact. In combination with previous findings (e.g., M. K. Johnson, A. M. Hermann, & J. L. Bonilla, 1995), these results suggest that the reflective processes necessary for deciding among competing alternatives show disruption early in the disease process. Such processing deficits would compound any difficulties arising from a degrading semantic structure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
84.
85.
86.
87.
The surface reaction products formed when sulfide minerals react with xanthates were analyzed by spectrophotometric methods. These products were found to be predominantly either metal xanthate or dixanthogen, depending on the particular sulfide mineral. Dixanthogen is formed on those minerals that, in a solution of xanthate, assume a rest potential greater than the equilibrium potential for the reduction of dixanthogen or xanthate.  相似文献   
88.
From the Rorschach findings presented, it can be inferred that "transorbital lobotomy results in a lessening of inner tension, a lessening of introspective self-awareness and insight, and a loss of ardent enthusiasm and active interest." A significant increase in W% is interpreted as some change in apperception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
89.
90.
Summary p-Aminobenzoylcaprolactam has been polymerized anionically in a two-step process to produce aramide-amide copolymers. Both drawn fibers and unoriented films may be produced using this method. The samples were characterized using FTIR, solution NMR, thermal analysis, viscosity, and mechanical testing. FTIR and NMR revealed the incorporation of both the aramid and amide linkages into the polymer backbone. TGA results gave a lower decomposition temperature than that of both aramide and nylon 6 materials. Intrinsic viscosities averaged 0.5 dL/g for the drawn copolymer samples polymerized by the di-functional initiator. Light microscopy displayed crystalline domains that did not appear to melt even up to 300°C. Mechanical testing showed that the initial moduli of drawn fiber samples to be in the range of 30–80 MPa, while homopolymers of nylon 6 and p-benzamide possessed values of 25 MPa and 2.70×103 MPa, respectively.  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