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   706202篇
  免费   50098篇
  国内免费   1296篇
耳鼻咽喉   9191篇
儿科学   23286篇
妇产科学   17678篇
基础医学   110732篇
口腔科学   19984篇
临床医学   64010篇
内科学   134378篇
皮肤病学   16179篇
神经病学   49567篇
特种医学   25841篇
外国民族医学   76篇
外科学   104620篇
综合类   14837篇
现状与发展   2篇
一般理论   163篇
预防医学   51482篇
眼科学   16381篇
药学   54150篇
  3篇
中国医学   2355篇
肿瘤学   42681篇
  2019年   5460篇
  2018年   7882篇
  2017年   6123篇
  2016年   6846篇
  2015年   7573篇
  2014年   10304篇
  2013年   15440篇
  2012年   20579篇
  2011年   21585篇
  2010年   12760篇
  2009年   11969篇
  2008年   20065篇
  2007年   21595篇
  2006年   21993篇
  2005年   20529篇
  2004年   20061篇
  2003年   19028篇
  2002年   18501篇
  2001年   36384篇
  2000年   36953篇
  1999年   30421篇
  1998年   7896篇
  1997年   6690篇
  1996年   6991篇
  1995年   6653篇
  1994年   6117篇
  1993年   5620篇
  1992年   23022篇
  1991年   22978篇
  1990年   22358篇
  1989年   22116篇
  1988年   20084篇
  1987年   19472篇
  1986年   18503篇
  1985年   17340篇
  1984年   12718篇
  1983年   10763篇
  1982年   5946篇
  1979年   11547篇
  1978年   8145篇
  1977年   6847篇
  1976年   6612篇
  1975年   7285篇
  1974年   8518篇
  1973年   8161篇
  1972年   7672篇
  1971年   7140篇
  1970年   6898篇
  1969年   6310篇
  1968年   5791篇
排序方式: 共有10000条查询结果,搜索用时 15 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