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   1305篇
  免费   186篇
  2021年   14篇
  2020年   14篇
  2018年   17篇
  2016年   17篇
  2015年   35篇
  2014年   41篇
  2013年   73篇
  2012年   73篇
  2011年   75篇
  2010年   47篇
  2009年   32篇
  2008年   44篇
  2007年   46篇
  2006年   43篇
  2005年   34篇
  2004年   42篇
  2003年   36篇
  2002年   35篇
  2001年   30篇
  2000年   47篇
  1999年   34篇
  1998年   18篇
  1997年   12篇
  1996年   19篇
  1995年   15篇
  1994年   16篇
  1993年   17篇
  1992年   25篇
  1991年   18篇
  1990年   28篇
  1989年   28篇
  1988年   23篇
  1987年   32篇
  1986年   19篇
  1985年   20篇
  1984年   21篇
  1983年   15篇
  1982年   16篇
  1981年   16篇
  1980年   12篇
  1979年   20篇
  1978年   19篇
  1977年   21篇
  1976年   16篇
  1975年   22篇
  1974年   14篇
  1973年   19篇
  1972年   17篇
  1966年   12篇
  1965年   11篇
排序方式: 共有1491条查询结果,搜索用时 192 毫秒
1.
The optimum conditions for using the method of radioimmunoprecipitation (RIP) for the detection of human immunodeficiency virus (HIV) in serum samples have been established. Out of several available cell lines persistently infected with HIV, specially selected line 17 has been chosen. The characteristic feature of this is the high and stable (under the conditions of prolonged cultivation) accumulation of virus-specific proteins in infected cells. The optimum conditions for making the test and its evaluation have also been established. The data of literature on the advantages of the method of RIP over such traditional methods as the enzyme immunoassay and immunoblotting have been confirmed. Thus, the presence of specific antibodies in several serum samples registered as false negative has been established. The intertypical reactivity of two serotypes of the virus, HIV-1 and HIV-2, has been studied. Cross reactivity of antibodies with respect to the HIV gene gag, but not with respect to viral glycoproteids, has been established. Ideas on the expediency and prospects of using RIP for the serological control of HIV infection are presented.  相似文献   
2.
Immunoblotting of isoelectric focusing gels of plasma and direct genomic DNA sequencing have been used to characterize a mutation in apolipoprotein A-I associated with the familial amyloidotic polyneuropathy originally described by Van Allen in an Iowa kindred. An arginine for glycine substitution in apolipoprotein A-I identified in the proband's amyloid fibrils was determined to be the result of a mutation of guanine to cytosine in the apolipoprotein A-I gene at the position corresponding to the first base of codon 26. Direct sequencing of genomic DNA of three affected individuals who died in the 1960s confirmed the inheritance of the disorder. Immunoblot analysis detected the variant apolipoprotein A-I in the proband's plasma and in several at-risk members of the kindred. In addition, allele-specific amplification by the polymerase chain reaction was used to detect carriers of the variant gene.  相似文献   
3.
4.
We have established by radioimmunoprecipitation that tyrosine-DOPA oxidase (TDO, tyrosinase) [EC 1.14.18.1] is first synthesized by frog embryos at the early neurula stage soon after embryonic induction of the neural plate by the underlying chordamesoderm. The DOPA moiety of the enzyme, at the time of its first appearance, is almost inactive enzymatically and can be activated by mild proteolysis (with trypsin). A very large increase in the amount of active DOPA oxidizing enzyme (without trypsinization) is observed at hatching (stage 21), and this is accompanied by melanin deposition in pigment cells. The tyrosine moiety of the enzyme is also partially inactive at the time of first synthesis, but the ratio of active to inactive enzyme remains approximately constant throughout early development. DOPA decarboxylase enzymatic activity is first detected at neurula stage, and this activity is accompanied by the first appearance of catechol amines.  相似文献   
5.
6.
7.
An outbreak of coccidioidomycosis occurred among 39 archeology students in the summer of 1972. The students excavated Indian ruins near Red Bluff in Tehama County, California, 20 miles north of the previously recognized northernmost limit of endemicity. At least 17 persons contracted an illness clinically compatible with a diagnosis of coccidioidomycosis. Coccidioidomycosis was documented by skin test conversion as well as by specific serologic reactions. Coccidioides immitis was also isolated from two soil samples taken at the excavation site. In light of its ecological requirements, it is doubtful that C. immitis will be recovered much farther north than Red Bluff. The occupational hazard of coccidioidomycosis to archeologists and others employed in known endemic areas remains a substantial threat to health.  相似文献   
8.
9.
The efficacy of the regular elicitation of the relaxation response in reducing surgical anxiety and pain in an ambulatory surgery setting was studied in a population of patients scheduled for the surgical removal of a skin cancer. Forty-nine patients with skin cancer were enrolled in the study immediately after being informed of the ned for surgery; 21 of these patients elicited the relaxation response 20 minutes per day until the day of surgery, 21 read for 20 minutes per day, and 7 were noncompliant and were excluded from the study. Contrary to expectations, neither group of patients showed any increase in anxiety immediately before or after surgery on either psychological or physiological measures. Thus, there were no differences between the two groups on any of the psychological or physiological measures of anxiety, nor were there any differences in pain perception. There were statistically significant subjective differences; the experimental patients stated that the relaxation-response technique had reduced their anxiety several days before surgery and reportedly experienced their highest levels of anxiety prior to entering the study, while the controls experienced their highest levels of anxiety during and after surgery. This suggests that (1) minor outpatient surgery does not lead to detectable increased anxiety levels on the day of surgery and (2) regular elicitation of the relaxation response can alter subjective reports of distress associated with surgery.  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