首页 | 官方网站   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   2645篇
  免费   123篇
  国内免费   27篇
医药卫生   2795篇
  2023年   15篇
  2022年   34篇
  2021年   58篇
  2020年   46篇
  2019年   67篇
  2018年   70篇
  2017年   48篇
  2016年   54篇
  2015年   56篇
  2014年   87篇
  2013年   120篇
  2012年   171篇
  2011年   188篇
  2010年   120篇
  2009年   103篇
  2008年   144篇
  2007年   161篇
  2006年   119篇
  2005年   117篇
  2004年   98篇
  2003年   98篇
  2002年   77篇
  2001年   59篇
  2000年   58篇
  1999年   41篇
  1998年   25篇
  1997年   21篇
  1996年   15篇
  1995年   16篇
  1994年   17篇
  1992年   30篇
  1991年   22篇
  1990年   34篇
  1989年   26篇
  1988年   29篇
  1987年   22篇
  1986年   28篇
  1985年   24篇
  1984年   19篇
  1983年   15篇
  1982年   17篇
  1980年   12篇
  1979年   23篇
  1978年   16篇
  1977年   17篇
  1976年   14篇
  1974年   12篇
  1972年   13篇
  1969年   18篇
  1968年   17篇
排序方式: 共有2795条查询结果,搜索用时 0 毫秒
1.
2.
The laryngeal mask in failed intubation   总被引:1,自引:0,他引:1  
  相似文献   
3.
4.
Truncus Arteriosus With Patent Ductus Arteriosus and Normal Aortic Arch   总被引:1,自引:0,他引:1  
In hearts with a common arterial trunk (truncus arteriosus), there is almost always an inverse development of the aortic arch and the ductus arteriosus. Truncus with a normal aortic arch and a patent ductus is a rare echocardiographic and surgical finding. In this report, we describe 2 neonates in whom truncus arteriosus with a normal aortic arch and a medium or large patent ductus was diagnosed by preoperative echocardiography (without catheterization) and confirmed intraoperatively.  相似文献   
5.
BACKGROUND: Elevated liver enzymes are infrequent in patients with hepatitis C virus (HCV) infection undergoing chronic hemodialysis (HD), suggesting that the alanine aminotransferase (ALT) is a poor predictor of hepatocellular damage in this population. OBJECTIVE: To establish a more appropriate cut-off value of ALT to identify biochemical activity due to HCV infection in HD patients. STUDY DESIGN: A total of 217 patients, with an average age of 51.2 years, were evaluated between January and October 2002; 130 were males (60%). Serum ALT was measured by a kinetic method in five consecutive monthly blood samples, from which an average was obtained and divided by the upper limit of normal (ULN). HCV antibodies were determined using an enzyme immunoassay, the serum HCV-RNA by nested-PCR and HCV genotype by hybridization of the amplified sequence from the 5'-non-coding region. The cut-off value of ALT was obtained from a ROC curve. RESULTS: Within the 217 patients, 18 (8.3%) were anti-HCV-positive, 17 (7.8%) of whom were also HCV-RNA-positive. Genotype distribution was: 1a=47%; 1b=18%; 3a=35%. Mean ALT/ULN (0.77+/-0.57) of the 18 anti-HCV-positive cases was higher (p<0.001) than the negative group (0.38+/-0.23). The mean ALT/ULN (0.81+/-0.57) of the 17 HCV-RNA-positive cases was also higher (p<0.0001) than the negative cases (0.37+/-0.23). The cut-off value of ALT to distinguish the anti-HCV-positive from negative patients was 0.50% or 50% of the ULN (sensitivity=67%; specificity=83%). According to the HCV-RNA, the cut-off value of ALT was 0.45% or 45% of the ULN (sensitivity=71%; specificity=80%). CONCLUSION: Reducing the cut-off of ALT by half, enables a better identification of biochemical activity in patients with HCV infection on chronic HD.  相似文献   
6.
7.
Administration of supraphysiological doses of testosterone to normal men causes inhibition of spermatogenesis, but while most become azoospermic, 30-55% maintain a low rate of spermatogenesis. We have investigated whether there are differences in endogenous androgen production, of testicular and adrenal origin, which may be related to the degree of suppression of spermatogenesis. Thirty-three healthy Caucasian men were given weekly i.m. injections of 200 mg testosterone oenanthate (TE), 18 became azoospermic, while 15 remained oligozoospermic. Urinary excretion of epitestosterone, a specific testicular product, was reduced to <10% of pretreatment values, with no differences between the groups. Similar results were obtained for other markers of testicular steroidogenesis. Urinary and plasma adrenal androgens were also reduced during TE treatment: a statistically significant decrease in both (P < 0.001 and P < 0.05 respectively) was seen in the azoospermic but not oligozoospermic responders. These results suggest that testicular steroidogenesis is decreased to <10% by the administration of supraphysiological doses of exogenous testosterone. Differences in the degree of ongoing steroidogenesis in the testis do not appear to account for incomplete suppression of spermatogenesis, thus differences in androgen metabolism may underlie this heterogeneous response. A small but significant reduction in secretion of adrenal androgens was also detectable, the relevance of which is unclear.   相似文献   
8.
Hamartomas were first described by Albrecht in 1904, who defined them as tumor-like malformations in which there was abnormal blending of the normal components of an organ. The myoid hamartoma is a rare benign lesion of the breast and has an uncertain origin, possibly in the walls of the blood vessels, muscularis mammillae of the areolae, and mainly in myoepithelium. We report 3 cases of myoid hamartomas of the breast, with the clinical, radiologic, and histopathological findings, and review the literature. The 3 lesions showed normal breast ducts and lobules, entrapped by a muscular stroma and some foci of mature adipose tissue. The muscular origin of part of the stroma was confirmed by strong reactiveness with smooth-muscle actin.  相似文献   
9.
10.
An 18-year-old woman was evaluated because of primary amenorrhea and hypogonadism. Chromosome analysis from peripheral blood lymphocytes revealed a nonmosaic 46,X,+mar constitution. The marker was shown to be a rearranged Y chromosome consisting of an inverted duplication of the long arm: rea(Y)(qter-q11::q11-qter). Deletion mapping analysis with Y-specific STS showed that the marker lacked Yp and Y-centromeric (DYZ3) sequences, but it was positive for Yq sequences tested. Fluorescence in situ hybridization analysis with Y and X chromosome centromeric and pancentromeric probes showed no hybridization signals. The marker chromosome is present in 100% of the cells; therefore, it is mitotically stable despite the absence of DYZ3 centromeric sequence. Hybridization with CENP-A and CENP-C specific antibodies localized a neocentromere close to the breakpoint.  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-23

京公网安备 11010802026262号