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   2043217篇
  免费   137789篇
  国内免费   4360篇
医药卫生   2185366篇
  2018年   21288篇
  2017年   17949篇
  2016年   18916篇
  2015年   22173篇
  2014年   28675篇
  2013年   40695篇
  2012年   57902篇
  2011年   56521篇
  2010年   33084篇
  2009年   33169篇
  2008年   51616篇
  2007年   56527篇
  2006年   57394篇
  2005年   62395篇
  2004年   62506篇
  2003年   56618篇
  2002年   51421篇
  2001年   92821篇
  2000年   93527篇
  1999年   81166篇
  1998年   21370篇
  1997年   18926篇
  1996年   18588篇
  1995年   17627篇
  1994年   16454篇
  1992年   64609篇
  1991年   63449篇
  1990年   62550篇
  1989年   61257篇
  1988年   56686篇
  1987年   55760篇
  1986年   53247篇
  1985年   50300篇
  1984年   37263篇
  1983年   31579篇
  1982年   18140篇
  1979年   35884篇
  1978年   25378篇
  1977年   21661篇
  1976年   19970篇
  1975年   23070篇
  1974年   27413篇
  1973年   26408篇
  1972年   25197篇
  1971年   23746篇
  1970年   22583篇
  1969年   21511篇
  1968年   20051篇
  1967年   18100篇
  1966年   16664篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
21.
Introduction: Percutaneous renal mass biopsy has evolved over the last decade with improvements on previous pitfalls including low tissue yield, high non-diagnostic rates, and complications. As understanding of tumor biology and natural history of renal cortical neoplasms has improved, percutaneous renal mass biopsy is poised to have an expanding role in an area characterized by individualized management and refined risk stratification.

Areas covered: This review summarizes the evolution of renal mass biopsy to its current state with respect to outcomes, indications, and clinical guidelines.

Expert opinion: With improved understanding of differential biological potential of renal cortical neoplasms combined with technical improvements in diagnostic yield and accuracy, utilization of renal mass biopsy is becoming an important adjunct to patient care in a broad range of clinical scenarios, including active surveillance, thermal ablation, and use of primary systemic therapy in localized and advanced settings.  相似文献   

22.
23.
24.
25.
26.
27.
28.
29.
30.
The purpose of this investigation was to characterize noise levels in spaces designated as “effective quiet” areas on a U.S. Navy aircraft carrier. Noise dosimetry samples were collected in 15 designated spaces, representing 15 noise measurements, while at-sea during airwing carrier qualifications. Equivalent sound level (Leq) measurements were collected during flight operations (Leq (flt ops)), non-flight operations (Leq (non-flt ops)), and over 24-hr periods (Leq (24-hr)). These data were compared to the 70 dBA American Conference of Governmental Industrial Hygienists (ACGIH®) Threshold Limit Value (TLV®) for “effective quiet” areas intended for temporary threshold shift recovery when personnel live and work in a potentially noise hazardous environment for periods greater than 24?hr. The monitored areas were selected based on personnel occupancy/use during off-duty time periods. Areas were classified by either (1) leisure areas that included mess (eating areas), gyms, lounges, an internet cafe, and the fantail social area or (2) berthing (sleeping) areas. The Leq measurements in decibels “A” weighted (dBA) were compared to determine significant differences between Leq (flt ops), Leq (non-flt ops), and Leq (24-hr) and were compared between leisure area and berthing area. Measured noise levels according to time period ranged as follows: (1) Leq (24-hr): 70.8–105.4 dBA; (2) Leq (flt ops): 70–101.2 dBA; and (3) Leq (non-flt ops): 39.4–104.6 dBA. All area measurements over the 24-hr period and during flight operations and 46.7% of the areas during the non-flight operation time period exceeded the “effective quiet” 70 dBA ACGIH TLV. Mean Leqs were 15 dBA higher during flight operations compared to non-flight operations in “effective quiet” areas (p?=?0.001). The Leqs in leisure areas were significantly higher than berthing areas by approximately 21 dBA during non-flight operation periods (p?=?0.001). Results suggest noise levels in “effective quiet” areas frequented by aircraft carrier personnel during off-duty hours when at-sea may inhibit auditory recovery from occupational noise exposures that occur on-duty.  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