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   556389篇
  免费   3856篇
  国内免费   863篇
电工技术   9952篇
综合类   468篇
化学工业   88159篇
金属工艺   24429篇
机械仪表   18123篇
建筑科学   12238篇
矿业工程   4797篇
能源动力   13678篇
轻工业   41649篇
水利工程   7312篇
石油天然气   15962篇
武器工业   36篇
无线电   56418篇
一般工业技术   117783篇
冶金工业   90025篇
原子能技术   15122篇
自动化技术   44957篇
  2021年   5476篇
  2020年   4368篇
  2019年   5508篇
  2018年   9038篇
  2017年   9096篇
  2016年   9697篇
  2015年   5899篇
  2014年   10079篇
  2013年   24999篇
  2012年   15303篇
  2011年   20141篇
  2010年   16213篇
  2009年   18189篇
  2008年   18353篇
  2007年   18067篇
  2006年   15551篇
  2005年   13973篇
  2004年   13422篇
  2003年   13160篇
  2002年   12734篇
  2001年   12354篇
  2000年   11812篇
  1999年   11471篇
  1998年   25685篇
  1997年   18824篇
  1996年   14639篇
  1995年   11379篇
  1994年   10336篇
  1993年   10165篇
  1992年   7976篇
  1991年   7897篇
  1990年   7717篇
  1989年   7517篇
  1988年   7193篇
  1987年   6626篇
  1986年   6453篇
  1985年   7149篇
  1984年   6683篇
  1983年   6456篇
  1982年   5862篇
  1981年   5976篇
  1980年   5777篇
  1979年   5949篇
  1978年   5862篇
  1977年   6417篇
  1976年   7754篇
  1975年   5364篇
  1974年   5223篇
  1973年   5318篇
  1972年   4619篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Oxidized low-density lipoprotein (ox-LDL) is the most harmful form of cholesterol associated with vascular atherosclerosis and hepatic injury, mainly due to inflammatory cell infiltration and subsequent severe tissue injury. Lox-1 is the central ox-LDL receptor expressed in endothelial and immune cells, its activation regulating inflammatory cytokines and chemotactic factor secretion. Recently, a Lox-1 truncated protein isoform lacking the ox-LDL binding domain named LOXIN has been described. We have previously shown that LOXIN overexpression blocked Lox-1-mediated ox-LDL internalization in human endothelial progenitor cells in vitro. However, the functional role of LOXIN in targeting inflammation or tissue injury in vivo remains unknown. In this study, we investigate whether LOXIN modulated the expression of Lox-1 and reduced the inflammatory response in a high-fat-diet mice model. Results indicate that human LOXIN blocks Lox-1 mediated uptake of ox-LDL in H4-II-E-C3 cells. Furthermore, in vivo experiments showed that overexpression of LOXIN reduced both fatty streak lesions in the aorta and inflammation and fibrosis in the liver. These findings were associated with the down-regulation of Lox-1 in endothelial cells. Then, LOXIN prevents hepatic and aortic tissue damage in vivo associated with reduced Lox-1 expression in endothelial cells. We encourage future research to understand better the underlying molecular mechanisms and potential therapeutic use of LOXIN.  相似文献   
992.
Aging is one of the most intriguing processes of human ontogenesis. It is associated with the development of a wide variety of diseases affecting all organs and their systems. The victory over aging is the most desired goal of scientists; however, it is hardly achievable in the foreseeable future due to the complexity and ambiguity of the process itself. All body systems age, lose their performance, and structural disorders accumulate. The cardiovascular system is no exception. And it is cardiovascular diseases that occupy a leading position as a cause of death, especially among the elderly. The aging of the cardiovascular system is well described from a mechanical point of view. Moreover, it is known that at the cellular level, a huge number of mechanisms are involved in this process, from mitochondrial dysfunction to inflammation. It is on these mechanisms, as well as the potential for taking control of the aging of the cardiovascular system, that we focused on in this review.  相似文献   
993.
Alzheimer’s disease (AD) is a multifactorial pathology characterized by β-amyloid (Aβ) deposits, Tau hyperphosphorylation, neuroinflammatory response, and cognitive deficit. Changes in the bacterial gut microbiota (BGM) have been reported as a possible etiological factor of AD. We assessed in offspring (F1) 3xTg, the effect of BGM dysbiosisdysbiosis in mothers (F0) at gestation and F1 from lactation up to the age of 5 months on Aβ and Tau levels in the hippocampus, as well as on spatial memory at the early symptomatic stage of AD. We found that BGM dysbiosisdysbiosis with antibiotics (Abx) treatment in F0 was vertically transferred to their F1 3xTg mice, as observed on postnatal day (PD) 30 and 150. On PD150, we observed a delay in spatial memory impairment and Aβ deposits, but not in Tau and pTau protein in the hippocampus at the early symptomatic stage of AD. These effects are correlated with relative abundance of bacteria and alpha diversity, and are specific to bacterial consortia. Our results suggest that this specific BGM could reduce neuroinflammatory responses related to cerebral amyloidosis and cognitive deficit and activate metabolic pathways associated with the biosynthesis of triggering or protective molecules for AD.  相似文献   
994.
计算流体力学模拟可检测拉幅干燥机内的气体流动过程,并对喷嘴指板后端和通风机上端潜在的问题区域进行检测。蒸发过程的模拟表明,织物表面温度与水分的分布不均匀。然而,由于缺乏设备对实验模拟数据进行认征,故无法判断其可靠性。  相似文献   
995.
Russian Journal of Non-Ferrous Metals - The influence of domestic nitrogen-containing corrosion inhibitors of the VNKh-L type on corrosion regularities of a zinc coating on steel in neutral media...  相似文献   
996.
Russian Journal of Non-Ferrous Metals - Currently, critical components and assemblies made of traditional materials do not always meet the increased requirements of designers and service...  相似文献   
997.
Powder Metallurgy and Metal Ceramics - The paper analyzes how the antifriction composites produced from AK12MMgN silumin grinding waste with MoS2 solid lubricant additions acquire their structure...  相似文献   
998.
Powder Metallurgy and Metal Ceramics - The stage-by-stage mechanism of the reduction process proceeding in an acidic environment in the cathodic depolarization of ammonium sulfate (NH4)2SO4...  相似文献   
999.
Powder Metallurgy and Metal Ceramics - The wetting of solid titanium substrates with liquid lithium and magnesium fluorides was studied by the sessile drop method in 1 · 10–3 Pa vacuum...  相似文献   
1000.
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