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   713342篇
  免费   50472篇
  国内免费   1339篇
耳鼻咽喉   9219篇
儿科学   23464篇
妇产科学   17712篇
基础医学   111622篇
口腔科学   19980篇
临床医学   64542篇
内科学   136497篇
皮肤病学   16273篇
神经病学   50152篇
特种医学   26073篇
外国民族医学   76篇
外科学   106079篇
综合类   14838篇
现状与发展   2篇
一般理论   162篇
预防医学   51725篇
眼科学   16382篇
药学   54505篇
  3篇
中国医学   2376篇
肿瘤学   43471篇
  2021年   5653篇
  2019年   5666篇
  2018年   8094篇
  2017年   6290篇
  2016年   7008篇
  2015年   7807篇
  2014年   10576篇
  2013年   15789篇
  2012年   21171篇
  2011年   22197篇
  2010年   13122篇
  2009年   12312篇
  2008年   20569篇
  2007年   22115篇
  2006年   22476篇
  2005年   21088篇
  2004年   20535篇
  2003年   19465篇
  2002年   18993篇
  2001年   36393篇
  2000年   36944篇
  1999年   30462篇
  1998年   7994篇
  1997年   6733篇
  1996年   7037篇
  1995年   6672篇
  1994年   6156篇
  1992年   22987篇
  1991年   22948篇
  1990年   22338篇
  1989年   22093篇
  1988年   20055篇
  1987年   19437篇
  1986年   18480篇
  1985年   17318篇
  1984年   12711篇
  1983年   10754篇
  1982年   5932篇
  1979年   11529篇
  1978年   8132篇
  1977年   6835篇
  1976年   6602篇
  1975年   7274篇
  1974年   8500篇
  1973年   8147篇
  1972年   7664篇
  1971年   7131篇
  1970年   6880篇
  1969年   6310篇
  1968年   5783篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
91.
Synthetic amorphous silica (SAS) in its nanosized form is now used in food applications although the potential risks for human health have not been evaluated. In this study, genotoxicity and oxidative DNA damage of two pyrogenic (NM‐202 and 203) and two precipitated (NM‐200 and ‐201) nanosized SAS were investigated in vivo in rats following oral exposure. Male Sprague Dawley rats were exposed to 5, 10, or 20 mg/kg b.w./day for three days by gavage. DNA strand breaks and oxidative DNA damage were investigated in seven tissues (blood, bone marrow from femur, liver, spleen, kidney, duodenum, and colon) with the alkaline and the (Fpg)‐modified comet assays, respectively. Concomitantly, chromosomal damage was investigated in bone marrow and in colon with the micronucleus assay. Additionally, malondialdehyde (MDA), a lipid peroxidation marker, was measured in plasma. When required, a histopathological examination was also conducted. The results showed neither obvious DNA strand breaks nor oxidative damage with the comet assay, irrespective of the dose and the organ investigated. Similarly, no increases in chromosome damage in bone marrow or lipid peroxidation in plasma were detected. However, although the response was not dose‐dependent, a weak increase in the percentage of micronucleated cells was observed in the colon of rats treated with the two pyrogenic SAS at the lowest dose (5 mg/kg b.w./day). Additional data are required to confirm this result, considering in particular, the role of agglomeration/aggregation of SAS NMs in their uptake by intestinal cells. Environ. Mol. Mutagen. 56:218–227, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   
92.
93.
94.
95.
96.
FGFR–TACC, found in different tumor types, is characterized by the fusion of a member of fibroblast grown factor receptor (FGFR) tyrosine kinase (TK) family to a member of the transforming acidic coiled-coil (TACC) proteins. Because chromosome numerical alterations, hallmarks of FGFR–TACC fusions are present in many hematological disorders and there are no data on the prevalence, we studied a series of patients with acute myeloid leukemia and myelodysplastic syndrome who presented numerical alterations using cytogenetic traditional analysis. None of the analyzed samples showed FGFR3–TACC3 gene fusion, so screening for this mutation at diagnosis is not recommended.  相似文献   
97.
98.
99.
Traditionally, major complications and unanticipated admission/readmission rates were used to assess outcome after day surgery. However, in view of the relative absence of major complications the quality of recovery (QOR) should be considered one of the principal endpoints after day surgery. In our study, the level of QOR is defined by a combination of the Global Surgical Recovery (GSR) Index and the Quality of Life (QOL).The aim of this study was to analyze prevalence and predictors of QOR after day surgery on the fourth postoperative day.Elective patients scheduled for day surgery from November 2008 to April 2010 were enrolled in a prospective cohort study. Outcome parameters were measured by using questionnaire packages at 2 time points: 1 week preoperatively and 4 days postoperatively. Primary outcome parameter is the QOR and is defined as good if the GSR index >80% as well as the postoperative QOL is unchanged or improved as compared with baseline. QOR is defined as poor if both the GSR index ≤80% and if the postoperative QOL is decreased as compared with baseline. QOR is defined as intermediate in all other cases. Three logistic regression analyses were performed to determine predictors for poor QOR after day surgery.A total of 1118 patients were included. A good QOR was noted in 17.3% of patients, an intermediate QOR in 34.8%, and a poor QOR in 47.8% 4 days after day surgery. The best predictor for poor QOR after day surgery was type of surgery. Other predictors were younger age, work status, and longer duration of surgery. A history of previous surgery, expected pain (by the patient) and high long-term surgical fear were significant predictors of poor QOR in only 1 of 3 prediction models.The QOR at home 4 days after day surgery was poor in the majority of patients and showed a significant procedure-specific variation. Patients at risk for poor QOR can be identified during the preoperative period based on type of surgery, age, work status, and the duration of the surgery.  相似文献   
100.
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