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   1222篇
  免费   89篇
电工技术   26篇
化学工业   263篇
金属工艺   18篇
机械仪表   25篇
建筑科学   19篇
矿业工程   1篇
能源动力   48篇
轻工业   142篇
水利工程   2篇
石油天然气   3篇
无线电   116篇
一般工业技术   177篇
冶金工业   197篇
原子能技术   5篇
自动化技术   269篇
  2023年   2篇
  2022年   12篇
  2021年   24篇
  2020年   32篇
  2019年   40篇
  2018年   35篇
  2017年   42篇
  2016年   37篇
  2015年   29篇
  2014年   49篇
  2013年   82篇
  2012年   55篇
  2011年   72篇
  2010年   50篇
  2009年   62篇
  2008年   70篇
  2007年   49篇
  2006年   32篇
  2005年   34篇
  2004年   36篇
  2003年   35篇
  2002年   26篇
  2001年   29篇
  2000年   23篇
  1999年   18篇
  1998年   73篇
  1997年   45篇
  1996年   37篇
  1995年   20篇
  1994年   21篇
  1993年   31篇
  1992年   4篇
  1991年   12篇
  1990年   6篇
  1989年   6篇
  1988年   8篇
  1987年   6篇
  1986年   4篇
  1985年   7篇
  1984年   7篇
  1983年   5篇
  1981年   4篇
  1980年   5篇
  1979年   3篇
  1978年   7篇
  1977年   4篇
  1976年   11篇
  1975年   3篇
  1974年   2篇
  1954年   1篇
排序方式: 共有1311条查询结果,搜索用时 203 毫秒
1.
Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disorder, affecting around 25% of the population worldwide. It is a complex disease spectrum, closely linked with other conditions such as obesity, insulin resistance, type 2 diabetes mellitus, and metabolic syndrome, which may increase liver-related mortality. In light of this, numerous efforts have been carried out in recent years in order to clarify its pathogenesis and create new prevention strategies. Currently, the essential role of environmental pollutants in NAFLD development is recognized. Particularly, endocrine-disrupting chemicals (EDCs) have a notable influence. EDCs can be classified as natural (phytoestrogens, genistein, and coumestrol) or synthetic, and the latter ones can be further subdivided into industrial (dioxins, polychlorinated biphenyls, and alkylphenols), agricultural (pesticides, insecticides, herbicides, and fungicides), residential (phthalates, polybrominated biphenyls, and bisphenol A), and pharmaceutical (parabens). Several experimental models have proposed a mechanism involving this group of substances with the disruption of hepatic metabolism, which promotes NAFLD. These include an imbalance between lipid influx/efflux in the liver, mitochondrial dysfunction, liver inflammation, and epigenetic reprogramming. It can be concluded that exposure to EDCs might play a crucial role in NAFLD initiation and evolution. However, further investigations supporting these effects in humans are required.  相似文献   
2.
3.
4.
5.
In this paper we review the results obtained in the last two years with the Orsay free electron laser.  相似文献   
6.
α,β‐Unsaturated nitriles have been synthesized by Knoevenagel condensation of a carbonylic compound with malononitrile, assisted by sonochemical irradiation. Two alkaline‐promoted clays (Li+‐ and Cs+‐exchanged saponites) have been employed as catalysts. The influence of the carbonylic compound (benzaldehyde or cyclohexanone) and the use of a solvent on the catalytic activity have been studied. Remarkable increase in the conversion values has been found when the reaction is activated by ultrasound, as compared with the thermal activation. In this green, solvent‐free procedure, α,β‐unsaturated nitriles have been produced in very high yields (97%) when the Cs+‐saponite is used as catalyst. Copyright © 2004 Society of Chemical Industry  相似文献   
7.
The stabilization problem for selected relative equilibria of an underactuated rigid body, modelling a simple underwater vehicle, moving in an ideal fluid is addressed. State feedback control laws achieving local asymptotic stability of a forward motion and of a diving/rising with forward/reverse motion are proposed. The control design exploits the Hamiltonian nature of the system to be controlled and it is based on the so-called interconnection and damping assignment (IDA) procedure. Simulation results complete the work.  相似文献   
8.
9.
The pattern of hepatitis C virus (HCV) viremia in blood donors who are positive for antibody to HCV (anti-HCV) according to the level of transaminase activity is unclear. A polymerase chain reaction-based HCV RNA detection method was used to study two clearly defined groups of anti-HCV-positive blood donors with repeatedly normal (n = 27) and elevated (n = 17) alanine aminotransferase (ALT) levels. HCV RNA was detected in only 4 of 27 blood donors with normal ALT values and 15 of 17 with elevated ALT values. These results indicate that anti-HCV-positive blood donors with normal ALT levels constitute a heterogeneous group, as HCV viremia is detectable in only a small proportion of cases. Polymerase chain reaction should be useful in the surveillance of anti-HCV-positive blood donors with normal ALT levels, by identifying those who might benefit from further investigation and treatment.  相似文献   
10.
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