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   95903篇
  免费   30250篇
  国内免费   1062篇
医药卫生   127215篇
  2024年   541篇
  2023年   5012篇
  2022年   1064篇
  2021年   2709篇
  2020年   5300篇
  2019年   1979篇
  2018年   6844篇
  2017年   7296篇
  2016年   7870篇
  2015年   7960篇
  2014年   10344篇
  2013年   12037篇
  2012年   3627篇
  2011年   3316篇
  2010年   6726篇
  2009年   8990篇
  2008年   3321篇
  2007年   2249篇
  2006年   3430篇
  2005年   1987篇
  2004年   1397篇
  2003年   1098篇
  2002年   1018篇
  2001年   1894篇
  2000年   1218篇
  1999年   1746篇
  1998年   2073篇
  1997年   1903篇
  1996年   1959篇
  1995年   1691篇
  1994年   1091篇
  1993年   931篇
  1992年   803篇
  1991年   689篇
  1990年   558篇
  1989年   565篇
  1988年   530篇
  1987年   410篇
  1986年   396篇
  1985年   327篇
  1984年   270篇
  1983年   317篇
  1982年   239篇
  1981年   205篇
  1980年   129篇
  1978年   153篇
  1977年   138篇
  1976年   94篇
  1974年   95篇
  1972年   91篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
OBJECTIVE: In 1991, a randomized study was published and demonstrated that use of nonsurgical therapy (chemoradiation) provided similar survival to total laryngectomy (the gold standard) for patients with advanced-stage laryngeal cancer. The purpose of this study was to assess how treatment of advanced laryngeal cancer was influenced by such developments in non-surgical therapy. STUDY DESIGN: Patterns of care study using National Cancer Database (1985-2001). RESULTS: The percentage of advanced-stage patients treated with chemoradiation increased from 8.3% to 20.8% while the proportion treated with radiation alone decreased from 38.9% to 23.0%. Use of chemoradiation increased at a significantly faster rate after the 1991 publication at both community cancer centers and teaching research facilities. The use of total laryngectomy decreased slightly during this period. CONCLUSIONS: The use of chemoradiation increased after the 1991 publication. It was impossible to determine from the NCDB whether additional patients who could benefit from chemo-RT were not offered or did not complete this treatment option. We recommend that treatment recommendations discussed at tumor boards be recorded in cancer registries.  相似文献   
994.
995.
996.
997.
998.
The potential for morbidity and mortality in patients who have PID with febrile and nonfebrile illness is extremely high. Familiarity with the clinical manifestations of PID and collaboration with a pediatric immunologist are prerequisites for optimal short-term care of these complex patients. Conservative management with empiric broad-spectrum antimicrobials, early and aggressive surgical debridement of abscesses, and admission at a tertiary pediatric care center are often indicated.  相似文献   
999.
1000.
Summary. Superoxide dismutase-like activity (SOD-like), isoenzyme lactate dehydrogenase-C4 (LDH-C4) and NADH-diaphorase activities in spermatozoa have been investigated from 58 normozoospermic and 27 oligozoospermic men. Significantly higher SOD-like, LDH-C4 and diaphorase activities ( P <0.01, P <0.005 and P <0.0001, respectively) were detected in spermatozoa from oligozoospermic men, compared to the activities found in normozoospermic samples. SOD-like activity (mean±SE) in oligozoospermic samples amounted to 8.3±1.6 U 10−8 spermatozoa, while in spermatozoa in normozoospermic men with a sperm concentration above 20 million of spermatozoa per ml amounted to 4.2±0.5 U 10−8. There was a close correlation between the SOD-like activity and biochemical indicators of the presence of residual cytoplasm i.e. isoenzyme LDH-C4 and NADH-diaphorase (r = 0.53 and r = 0.66 in normozoospermic and r = 0.63 and r = 0.54 in oligozoospermic men, respectively). A positive relationship between SOD-like activity and experimentally-induced lipid peroxidation was detected in 54 infertile men (r = 0.30; P <0.05). These findings suggest that a higher level of superoxide dismutase-like activity may reflect a defect in the development or maturation of spermatozoa and, thereby, a decreased fertility potential. Hence, determination of SOD-like activity may give information on the state of maturity of human spermatozoa, while its role in the antioxidative protection remains to be determined.  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