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   197997篇
  免费   2644篇
  国内免费   606篇
电工技术   3451篇
综合类   147篇
化学工业   28099篇
金属工艺   8042篇
机械仪表   6028篇
建筑科学   4761篇
矿业工程   1300篇
能源动力   5111篇
轻工业   16822篇
水利工程   2294篇
石油天然气   4019篇
武器工业   8篇
无线电   23042篇
一般工业技术   39992篇
冶金工业   37235篇
原子能技术   5087篇
自动化技术   15809篇
  2021年   1600篇
  2019年   1576篇
  2018年   2575篇
  2017年   2650篇
  2016年   2780篇
  2015年   1798篇
  2014年   3077篇
  2013年   8944篇
  2012年   5055篇
  2011年   7032篇
  2010年   5591篇
  2009年   6357篇
  2008年   6450篇
  2007年   6519篇
  2006年   5583篇
  2005年   5230篇
  2004年   5009篇
  2003年   4891篇
  2002年   4527篇
  2001年   4658篇
  2000年   4580篇
  1999年   4729篇
  1998年   11375篇
  1997年   8100篇
  1996年   6147篇
  1995年   4637篇
  1994年   4237篇
  1993年   4044篇
  1992年   3176篇
  1991年   3038篇
  1990年   2834篇
  1989年   2911篇
  1988年   2790篇
  1987年   2362篇
  1986年   2281篇
  1985年   2687篇
  1984年   2465篇
  1983年   2307篇
  1982年   2048篇
  1981年   2178篇
  1980年   2003篇
  1979年   2096篇
  1978年   2097篇
  1977年   2343篇
  1976年   3163篇
  1975年   1815篇
  1974年   1739篇
  1973年   1759篇
  1972年   1434篇
  1971年   1320篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
31.
Cardiovascular disease (CVD) is a leading cause of death worldwide. Elevated concentrations of serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) are major lipid biomarkers that contribute to the risk of CVD. Phytosterols well known for their cholesterol-lowering ability, are non-nutritive compounds that are naturally found in plant-based foods and can be classified into plant sterols and plant stanols. Numerous clinical trials demonstrated that 2 g phytosterols per day have LDL-C lowering efficacy ranges of 8–10%. Some observational studies also showed an inverse association between phytosterols and LDL-C reduction. Beyond the cholesterol-lowering beneficial effects of phytosterols, the association of phytosterols with CVD risk events such as coronary artery disease and premature atherosclerosis in sitosterolemia patients have also been reported. Furthermore, there is an increasing demand to determine the association of circulating phytosterols with vascular health biomarkers such as arterial stiffness biomarkers. Therefore, this review aims to examine the ability of phytosterols for CVD risk prevention by reviewing the current data that looks at the association between dietary phytosterols intake and serum lipid biomarkers, and the impact of circulating phytosterols level on vascular health biomarkers. The clinical studies in which the impact of phytosterols on vascular function is investigated show minor but beneficial phytosterols effects over vascular health. The aforementioned vascular health biomarkers are pulse wave velocity, augmentation index, and arterial blood pressure. The current review will serve to begin to address the research gap that exists between the association of dietary phytosterols with CVD risk biomarkers.  相似文献   
32.
Ischemic and hemorrhagic strokes are associated with severe functional disability and high mortality. Except for recombinant tissue plasminogen activator, therapies targeting the underlying pathophysiology of central nervous system (CNS) ischemia and hemorrhage are strikingly lacking. Sur1-regulated channels play essential roles in necrotic cell death and cerebral edema following ischemic insults, and in neuroinflammation after hemorrhagic injuries. Inhibiting endothelial, neuronal, astrocytic and oligodendroglial sulfonylurea receptor 1–transient receptor potential melastatin 4 (Sur1–Trpm4) channels and, in some cases, microglial KATP (Sur1–Kir6.2) channels, with glibenclamide is protective in a variety of contexts. Robust preclinical studies have shown that glibenclamide and other sulfonylurea agents reduce infarct volumes, edema and hemorrhagic conversion, and improve outcomes in rodent models of ischemic stroke. Retrospective studies suggest that diabetic patients on sulfonylurea drugs at stroke presentation fare better if they continue on drug. Additional laboratory investigations have implicated Sur1 in the pathophysiology of hemorrhagic CNS insults. In clinically relevant models of subarachnoid hemorrhage, glibenclamide reduces adverse neuroinflammatory and behavioral outcomes. Here, we provide an overview of the preclinical studies of glibenclamide therapy for CNS ischemia and hemorrhage, discuss the available data from clinical investigations, and conclude with promising preclinical results that suggest glibenclamide may be an effective therapeutic option for ischemic and hemorrhagic stroke.  相似文献   
33.
34.
35.
Morozov  Yu. D.  Pemov  I. F.  Matrosov  M. Yu.  Zin’ko  B. F. 《Metallurgist》2020,63(9-10):933-950
Metallurgist - We consider domestic and foreign standards for rolled metals used in bridge building. Domestic standards contain elevated requirements to the reliability of rolled metals in terms of...  相似文献   
36.
Russian Journal of Non-Ferrous Metals - This article is devoted to the influence of sodium lignosulfonate (SL), anionic surfactants (sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate...  相似文献   
37.
Catalysis in Industry - The oligomerization of 1-pentene is an efficient process for producing environmentally friendly high-quality fuel components. The catalytic properties of FAU, OFF, MOR, BEA,...  相似文献   
38.
Amlabu  B. A.  Umaru  S.  Dauda  M.  Obada  D. O.  Csaki  S.  Bansod  N. D.  Dodoo-Arhin  D.  Fasanya  O. O. 《SILICON》2020,12(6):1311-1324
Silicon - In this study, an evaluation has been made into the influence of milling time on the thermo-physical and fracture properties of a MgO-Al2O3-SiO2 system. The powdery and compacted...  相似文献   
39.
40.
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