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   707665篇
  免费   50220篇
  国内免费   1310篇
耳鼻咽喉   9248篇
儿科学   23422篇
妇产科学   17647篇
基础医学   110678篇
口腔科学   20031篇
临床医学   63861篇
内科学   134606篇
皮肤病学   16268篇
神经病学   49656篇
特种医学   25889篇
外国民族医学   77篇
外科学   105132篇
综合类   14898篇
现状与发展   2篇
一般理论   166篇
预防医学   51444篇
眼科学   16409篇
药学   54469篇
  3篇
中国医学   2387篇
肿瘤学   42902篇
  2021年   5604篇
  2018年   8022篇
  2017年   6198篇
  2016年   6954篇
  2015年   7683篇
  2014年   10432篇
  2013年   15607篇
  2012年   20842篇
  2011年   21801篇
  2010年   12902篇
  2009年   12087篇
  2008年   20255篇
  2007年   21763篇
  2006年   22135篇
  2005年   20654篇
  2004年   20179篇
  2003年   19121篇
  2002年   18583篇
  2001年   36429篇
  2000年   36979篇
  1999年   30452篇
  1998年   7902篇
  1997年   6691篇
  1996年   6999篇
  1995年   6656篇
  1994年   6122篇
  1993年   5618篇
  1992年   23026篇
  1991年   22978篇
  1990年   22344篇
  1989年   22104篇
  1988年   20061篇
  1987年   19442篇
  1986年   18486篇
  1985年   17336篇
  1984年   12714篇
  1983年   10749篇
  1982年   5912篇
  1979年   11514篇
  1978年   8130篇
  1977年   6817篇
  1976年   6586篇
  1975年   7259篇
  1974年   8498篇
  1973年   8140篇
  1972年   7660篇
  1971年   7136篇
  1970年   6877篇
  1969年   6303篇
  1968年   5785篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
101.
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   
102.
103.
104.
105.
106.
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   
107.
108.
109.
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   
110.
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