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   573篇
  免费   44篇
  国内免费   60篇
耳鼻咽喉   12篇
儿科学   40篇
妇产科学   7篇
基础医学   79篇
口腔科学   16篇
临床医学   93篇
内科学   137篇
皮肤病学   14篇
神经病学   11篇
特种医学   89篇
外科学   31篇
综合类   23篇
预防医学   36篇
眼科学   7篇
药学   43篇
中国医学   3篇
肿瘤学   36篇
  2023年   2篇
  2022年   3篇
  2021年   4篇
  2020年   4篇
  2019年   11篇
  2018年   11篇
  2017年   5篇
  2016年   10篇
  2015年   13篇
  2014年   27篇
  2013年   27篇
  2012年   13篇
  2011年   16篇
  2010年   28篇
  2009年   28篇
  2008年   28篇
  2007年   51篇
  2006年   16篇
  2005年   14篇
  2004年   11篇
  2003年   5篇
  2002年   8篇
  2001年   8篇
  2000年   4篇
  1999年   14篇
  1998年   33篇
  1997年   37篇
  1996年   23篇
  1995年   22篇
  1994年   29篇
  1993年   20篇
  1992年   5篇
  1991年   10篇
  1990年   3篇
  1989年   18篇
  1988年   18篇
  1987年   11篇
  1986年   4篇
  1985年   10篇
  1984年   7篇
  1983年   4篇
  1982年   10篇
  1981年   12篇
  1980年   8篇
  1978年   7篇
  1977年   7篇
  1976年   10篇
  1975年   4篇
  1966年   1篇
  1957年   1篇
排序方式: 共有677条查询结果,搜索用时 15 毫秒
1.
Balloon dacryocystoplasty: indications and contraindications   总被引:3,自引:0,他引:3  
  相似文献   
2.
The molecular mechanisms involved in luteolysis are still unclear in the primate. This study aimed to investigate the effect of induced luteolysis on the ovarian luteinizing hormone (LH) receptor and the steroidogenic enzyme, 3beta-hydroxysteroid dehydrogenase (3beta-HSD) in the marmoset monkey. Luteolysis was induced in the mid-luteal phase either directly by systemic prostaglandin F2alpha (PGF2alpha), or indirectly by LH withdrawal using systemic gonadotrophin releasing hormone antagonist (GnRHant) treatment. The LH receptor was studied by isotopic mRNA in-situ hybridization and in-situ ligand binding and 3beta-HSD expression was studied using isotopic mRNA in-situ hybridization and immunohistochemistry. Induced luteolysis was associated with a reduction in the expression of LH receptor (P < 0.0001) and 3beta-HSD mRNA, closely followed by a reduction in the LH receptor (P < 0.05) and 3beta-HSD protein concentrations within 24 h. There were no differences in the findings whether luteolysis was induced with PGF2alpha or GnRHant. This study shows that disparate mechanisms to induce luteolysis in the primate result in an identical rapid loss of the LH receptor and 3beta-HSD. In conclusion, induced luteolysis leads to rapid loss of the steroidogenic pathway in luteal cells.   相似文献   
3.
4.
5.
We evaluated 14 patients with bilateral testicular tumour, one-sided tumour and contralateral carcinoma in situ (CIS) of the testis or testis tumour in single testis with respect to their fertility. We analysed semen parameters, serum hormones [follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone], testicular sonography, testicular volumes and testicular histology prior to further anti-cancer treatment. Ten out of 14 patients showed normal or reduced sperm concentrations, while 4/14 patients were azoospermic. Serum FSH levels showed a significant negative correlation with sperm concentrations in patients with testicular malignancies (r = -0.64, P = 0.025). Testicular volumes revealed a significant positive correlation with semen parameters in patients with testes that were affected by CIS (r = 0.733, P = 0.038). We conclude that even bilateral testicular cancer and/or CIS do not preclude fertility and, therefore, patients should be offered andrological investigation and therapy, including possibly surveillance strategy or the chance for cryopreservation of the semen prior to further treatment in order to preserve their chances for paternity.   相似文献   
6.
7.
8.
9.
OBJECTIVES: To determine the spectrum of N and G genotypes of respiratory syncytial virus (RSV) causing respiratory tract infection and whether particular genotypes are associated with severity of infection. PATIENTS AND METHODS: Nasopharyngeal aspirates (NPAs) were obtained from 114 infants with acute respiratory tract infection due to RSV over two seasons. Viral mRNA was extracted from NPAs or cultured virus, reverse transcribed, and the cDNA amplified by the polymerase chain reaction using primers directed to parts of the N and G gene respectively. Amplicons were separately digested with four different restriction endonucleases for each gene. The fragments were separated by agarose gel, electrophoresis, and the electrophoretic patterns used to assign the various genotypes. Disease severity was assessed as very mild (upper respiratory tract signs only), mild (coryza and signs of lower respiratory tract infection), moderate (requiring nasogastric or intravenous fluids), and severe (requiring oxygen or ventilation). RESULTS: Five of the six known N genotypes were detected, but NP4 and NP2 were found most frequently. There was no association between N genotype and disease severity. Six G (SHL) genotypes were detected. Significantly (p = 0.04) more of the infants infected with the SHL2 genotype had severe or moderate disease. CONCLUSIONS: During the seasonal peaks of RSV respiratory tract infection at least 10 different RSV genotypes cocirculated. While there is no association between N genotypes and disease severity, infection with the SHL2 G genotype appears to result in moderate to severe disease.  相似文献   
10.
BackgroundEpstein-Barr virus (EBV) is a member of the herpesvirus family that is known to ubiquitously infect people worldwide. However, the actual prevalence of EBV infection in diseased patients in Nigeria, remains unknown. This study was thus conducted to ascertain the true prevalence.MethodsA systematic review and meta-analysis of published data was conducted according to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Electronic databases including PubMed, Scopus, ScienceDirect, and Google Scholar were searched for studies reporting the occurrence of EBV infection among patients with established diseases. Studies were included if they assessed EBV infection in diseased patients in Nigeria. Data were extracted and subsequently analysed using R software. Funnel plot and Egger's regression test was used to assess publication bias, while JBI prevalence tool was used to assess study quality.ResultsA total of 13 studies covering 228 cases of EBV infection among 1157 diseased patients were included. Summary estimates were computed using random-effects model. The pooled prevalence of EBV infection was 20.3% (95% CI: 10.8–34.9, I2 ?= ?92.26, p ?< ?0.001). When stratified according to the type of disease, higher estimates were obtained for patients suffering from Kaposi's sarcoma (98.7%, 95% CI: 82.2–99.9) and Nasopharyngeal malignancy (85.7%, 95% CI: 70.0–93.9). A prevalence of 13.4% (95% CI: 6.0–27.4) and 12.2% (95% CI: 4.8–27.8) was derived for the most reported patient populations, lymphoma and HIV, respectively.ConclusionThis first meta-analysis on the prevalence of EBV among Nigerian patients suffering from various diseases reveals a prevalence that emphasises the need to routinely monitor EBV infection in all EBV-associated diseases in Nigeria.  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