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   811篇
  免费   44篇
  国内免费   19篇
耳鼻咽喉   2篇
儿科学   33篇
妇产科学   2篇
基础医学   88篇
口腔科学   50篇
临床医学   46篇
内科学   119篇
皮肤病学   16篇
神经病学   197篇
特种医学   115篇
外科学   41篇
综合类   13篇
预防医学   25篇
眼科学   58篇
药学   49篇
肿瘤学   20篇
  2023年   5篇
  2022年   3篇
  2021年   5篇
  2020年   5篇
  2019年   8篇
  2018年   14篇
  2017年   5篇
  2016年   13篇
  2015年   13篇
  2014年   23篇
  2013年   28篇
  2012年   22篇
  2011年   24篇
  2010年   29篇
  2009年   24篇
  2008年   26篇
  2007年   41篇
  2006年   31篇
  2005年   29篇
  2004年   34篇
  2003年   25篇
  2002年   30篇
  2001年   29篇
  2000年   9篇
  1999年   14篇
  1998年   27篇
  1997年   19篇
  1996年   16篇
  1995年   22篇
  1994年   15篇
  1993年   19篇
  1992年   21篇
  1991年   16篇
  1990年   17篇
  1989年   29篇
  1988年   23篇
  1987年   30篇
  1986年   20篇
  1985年   19篇
  1984年   8篇
  1983年   4篇
  1982年   9篇
  1981年   9篇
  1980年   12篇
  1979年   5篇
  1978年   11篇
  1977年   9篇
  1976年   9篇
  1975年   9篇
  1955年   2篇
排序方式: 共有874条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients.  相似文献   
5.
6.
7.
Following a recent report that two isolates of Mycobacterium terrae complex had given positive reactions with M. tuberculosis complex DNA probes, a joint study was undertaken to determine the extent of these findings in the clinical culture collection holdings of two state health laboratories. A total of 117 M. terrae complex strains (identified by standard biochemical methods) were subjected to M. tuberculosis complex probe testing with the two then-available kits (from Syngene, Inc., and Gen-Probe, Inc.). In addition to the two original isolates first reported, two further M. terrae complex isolates were found to react with the M. tuberculosis complex probes. Two modifications of the Accuprobe (Gen-Probe, Inc.) test method were evaluated. Extension of the selection time to 8 min was the most convenient modification and rendered the M. terrae complex isolates negative when tested with the Accuprobe M. tuberculosis complex probe. However, the effects of increased selection time on the overall sensitivity of the M. tuberculosis complex probe require further study.  相似文献   
8.
The nitric oxide pathway in pre-eclampsia: pathophysiological implications   总被引:2,自引:0,他引:2  
Pre-eclampsia, one of the most significant health problems inhuman pregnancy, complicates 6-7% of all gestations and is theleading cause of fetal growth retardation, infant morbidityand mortality, premature birth and maternal death. Recent researchimplicates free radicals in the pathophysiology of pre-eclampsia.This review covers the biochemistry of nitric oxide (NO) andpossible interactions with other free radicals. Studies in therat show that pregnancy is associated with enhanced productionand responsiveness to NO in both reproductive tissues and bloodvessels. Rats infused with NG-nitro-L-arginine methyl ester(L-NAME, a NO synthase inhibitor) have been used as an animalmodel of pre-eclampsia, and the effects of steroid hormoneson blood pressure in this model have been tested. Results suggestthat pre-eclampsia may be a state of NO deficiency. However,in humans there seem to be contradictions regarding the involvementof NO in maternal adaptation to pregnancy. It is suggested thatNO may be one of several systems that act in concert to maintaina symbiotic relationship between mother and fetus. However,the input of each system may be genetically determined.  相似文献   
9.
Male genital tract obstructions may result from infections, previous inguinal and scrotal surgery (vasectomy) and congenital bilateral absence of the vas deferens (CBAVD). Microsurgery can sometimes be successful in treating the obstruction. In other cases and in cases of failed surgical intervention, the patient can be treated by microsurgical or percutaneous epididymal sperm aspiration (MESA, PESA) or testicular sperm extraction (TESE) and intracytoplasmic sperm injection (ICSI). We present the results of 39 ICSI procedures for obstructive azoospermia in 24 couples. The aetiology of the obstruction was failed microsurgery in 11 patients, CBAVD in nine and genital infections in four. Sperm retrieval was accomplished via MESA in four cases, PESA in 18 cases and via TESE in 11 cases. TESE was only applied when PESA failed to produce enough spermatozoa for simultaneous ICSI. In six patients, the ICSI procedure was performed with cryopreserved spermatozoa after an initial PESA procedure. Fertilization occurred in 47% of the metaphase II oocytes; embryo transfer was performed in 92% of procedures and resulted in a clinical pregnancy in 13/39 procedures. Ongoing pregnancy was achieved in 10/39 procedures. One pregnancy was terminated early after prenatal investigation showed a cytogenetic abnormality (47,XX+18, Edwards syndrome). The other nine pregnancies resulted in the live birth of 10 children, without any congenital abnormalities. Epididymal and testicular retrieved spermatozoa were successfully used for ICSI to treat obstructive azoospermia, and resulted in an ongoing pregnancy in 10 of 24 couples (41.6%) after 39 ICSI procedures, a success rate of 25.6% per treatment cycle and of 27.7% per embryo transfer.   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