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   1238篇
  免费   12篇
  国内免费   3篇
电工技术   2篇
综合类   3篇
化学工业   221篇
金属工艺   108篇
机械仪表   12篇
建筑科学   9篇
矿业工程   10篇
能源动力   1篇
轻工业   51篇
水利工程   8篇
石油天然气   64篇
无线电   32篇
一般工业技术   108篇
冶金工业   576篇
原子能技术   14篇
自动化技术   34篇
  2021年   12篇
  2019年   20篇
  2018年   22篇
  2017年   22篇
  2016年   30篇
  2015年   15篇
  2014年   14篇
  2013年   22篇
  2012年   15篇
  2011年   30篇
  2010年   27篇
  2009年   23篇
  2008年   24篇
  2007年   25篇
  2006年   14篇
  2005年   28篇
  2004年   15篇
  2003年   18篇
  2002年   9篇
  2001年   9篇
  2000年   18篇
  1998年   131篇
  1997年   86篇
  1996年   71篇
  1995年   38篇
  1994年   25篇
  1993年   33篇
  1992年   14篇
  1991年   13篇
  1990年   16篇
  1989年   12篇
  1988年   12篇
  1987年   15篇
  1986年   16篇
  1985年   9篇
  1984年   13篇
  1983年   11篇
  1982年   14篇
  1981年   10篇
  1979年   8篇
  1978年   19篇
  1977年   43篇
  1976年   85篇
  1975年   13篇
  1974年   16篇
  1972年   15篇
  1971年   9篇
  1968年   9篇
  1967年   8篇
  1966年   8篇
排序方式: 共有1253条查询结果,搜索用时 15 毫秒
81.
Intracerebral infection of mice aged 2-3 days with hepatitis C virus (HCV) from chronically infected suckling mouse brain cultures and porcine embryo cells resulted in the death of animals after 12-14 days. Repeated passages of HCV in animals decreased the incubation period to just 3-4 days. Blood serum of surviving mice collected during the 4th week postinfection contained antiHCV antibodies detected by enzyme immunoassay and hemagglutination inhibition test. The results are proof of creation of a new in vivo model of experimental HCV infection.  相似文献   
82.
83.
We analyzed 79 consecutive patients with aneurysms and found a patient who lacked type III collagen. Collagen was extracted from the skin, and the lack of type III collagen was determined by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Only 1 of the 79 patients was found to lack type III collagen. This patient was a 55-year-old man who had sustained an abdominal aortic aneurysm and aortic dissection. He did not show any of the typical clinical symptoms of Ehlers-Danlos syndrome type IV, such as hyperextensible skin and joints. He had none of the usual risk factors nor any clear family history of the syndrome. Furthermore, his collagen fibrils demonstrated a homogeneous appearance. This case may represent a new form of type III collagen deficiency.  相似文献   
84.
A recent review of the relevant literature indicates that different approaches to the exploration of nurses' clinical reasoning are being adopted in North America, Australia and the United Kingdom. These differing approaches, which tend to cluster chronologically and which include decision analysis, information processing and skills acquisition theory and their limitations will be outlined; it will be argued that it is through their conflation that nurses' collective understanding of nurses' clinical reasoning is deepened. The author is attempting to develop an international network of nurse scholars interested in clinical reasoning with the aim of achieving this. The purposes of this network will be to facilitate international collaboration to expedite both the growth of knowledge related to nurses' clinical reasoning and the development of programs of international comparative research related to it. The setting up of this network and progress to date is described.  相似文献   
85.
86.
The purpose of this study was to assess the possibility of measuring directional microphone hearing aids (DMHAs) using standard hearing aid test instruments in a sound field environment. The use of DMHAs is increasing and research has shown that under certain difficult listening situations, superior results are obtained by hearing impaired individuals with directional versus omnidirectional microphone arrangements. However, valid electroacoustic evaluation of the DMHAs cannot be accomplished using the conventional hearing aid test box. The ideal environment for such evaluations is an anechoic chamber, a facility not found in most audiological clinics. Results show that if the proper precautions are observed, the electroacoustic characteristics of DMHAs can be measured in a sound field environment using conventional hearing aid test instrumentation. Validation of this procedure was carried out by comparing sound field results with those obtained in an anechoic chamber.  相似文献   
87.
88.
89.
Conclusions A study was made of the chemical stability of four powdered vanadium germanides (V3Ge, V5Ge3, V11Ge8, and VGe2) in acid and alkali solutions and their mixtures with solutions of oxidizing and complex forming agents, and also in atmospheric oxygen at 500–750°C. It is shown that vanadium germanides are unstable compounds, which are readily decomposed by hydrochloric, sulfuric, and nitric acids, hydrogen peroxide, and other reagents and also readily oxidized by the oxygen in the air at temperatures above 550°C.Translated from Poroshkovaya Metallurgiya, No. 5 (137), pp. 67–69, May, 1974.  相似文献   
90.
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