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   4564篇
  免费   5篇
电工技术   20篇
综合类   1篇
化学工业   21篇
金属工艺   1篇
建筑科学   4篇
轻工业   3篇
无线电   8篇
一般工业技术   23篇
冶金工业   4475篇
自动化技术   13篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2016年   1篇
  2014年   7篇
  2013年   15篇
  2012年   4篇
  2011年   3篇
  2009年   4篇
  2008年   2篇
  2007年   2篇
  2006年   6篇
  2005年   2篇
  2004年   9篇
  2003年   9篇
  2002年   1篇
  2001年   2篇
  2000年   2篇
  1999年   127篇
  1998年   1391篇
  1997年   848篇
  1996年   490篇
  1995年   268篇
  1994年   251篇
  1993年   279篇
  1992年   35篇
  1991年   50篇
  1990年   73篇
  1989年   61篇
  1988年   69篇
  1987年   64篇
  1986年   46篇
  1985年   35篇
  1984年   1篇
  1983年   8篇
  1982年   12篇
  1981年   30篇
  1980年   44篇
  1979年   3篇
  1978年   7篇
  1977年   92篇
  1976年   203篇
  1975年   5篇
  1964年   1篇
  1955年   3篇
排序方式: 共有4569条查询结果,搜索用时 140 毫秒
51.
Alagille syndrome (AGS) is one of the major forms of chronic liver disease in childhood with severe morbidity and a mortality of 10 to 20%. It is characterised by cholestasis of variable severity with paucity of interlobular bile ducts and anomalies of the cardiovascular system, skeleton, eyes, and face. Previous studies suggest a wide variation in the expression of the disease and a high incidence of new mutations. To determine more accurately the rate of new mutations and to develop criteria for detecting the disorder in parents we systematically investigated parents in 14 families with an affected child. Clinical examination was supplemented by liver function tests, echocardiography, radiographic examination of the spine and forearm, ophthalmological assessment, and chromosome analysis. Six parents had typical anomalies in two or more systems pointing to the presence of autosomal dominant inheritance. Systematic screening of parents for the features defined in this study should improve the accuracy of genetic counselling.  相似文献   
52.
53.
54.
It is essential to know how the immune system acts in different neurological diseases, some of them non very well known or of unknown etiology at all. It was applied Reiber and Felgenhauer's formula in 56 patients with different diseases. IgA, IgM, IgG and albumin were quantified in sera and cerebrospinal fluid by simple immunodiffusion. It was observed more frequent IgG local synthesis and IgA in this sample.  相似文献   
55.
56.
57.
58.
59.
An outbreak of 154 cases of vampire bat biting in a four-month period in the gold mine of Payapal, a Venezuelan village, is reported. All patients were bitten during the night and the most bites were on their toes. No complication attributed to the bite was reported. Diagnoses of rabies virus made by means of immunofluorescence were negative. A possible reason for this outbreak may been the development of mining areas, with the inhabitants providing an alternative food source for the bats.  相似文献   
60.
It is important to monitor the early stages of postoperative wound repair in order to identify those problems associated with impaired healing. Many of the crucial cellular responses of early wound healing, such as inflammatory infiltration, angiogenesis and re-epithelialization, are made possible through the action of matrix metalloproteinases (MMPs). Expression of MMP-2 and MMP-9 is elevated in acute wounds, and still greater levels are found in chronic wounds, indicating that uncontrolled proteolysis is a characteristic of retarded healing. Therefore, comparative measurements of MMPs may be used to monitor the progression of early wound healing. To investigate this, wound fluids and sera were collected from mastectomy and colectomy patients throughout early stages of repair, and the temporal expression profile established. Wounds which were healing were expressed maximal levels of MMP-9 at 24 h, followed by a significant decline by 48 h. Persistent elevation of MMP-9 expression was associated with infected and chronic wounds, and was identified in postoperative wounds by the absence of the significant decline between 24 and 48 h. Measurement of MMP-9 in postoperative wound fluids, therefore, provides an early indicator of impaired healing, which may be evaluated non-invasively within 48 h of closure.  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