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   706065篇
  免费   49904篇
  国内免费   1301篇
耳鼻咽喉   9181篇
儿科学   23291篇
妇产科学   17607篇
基础医学   110528篇
口腔科学   20026篇
临床医学   63827篇
内科学   134727篇
皮肤病学   16169篇
神经病学   49504篇
特种医学   25798篇
外国民族医学   76篇
外科学   104551篇
综合类   14821篇
现状与发展   2篇
一般理论   160篇
预防医学   51438篇
眼科学   16354篇
药学   54107篇
  3篇
中国医学   2362篇
肿瘤学   42738篇
  2019年   5442篇
  2018年   7881篇
  2017年   6118篇
  2016年   6835篇
  2015年   7563篇
  2014年   10287篇
  2013年   15409篇
  2012年   20564篇
  2011年   21534篇
  2010年   12743篇
  2009年   11938篇
  2008年   20032篇
  2007年   21575篇
  2006年   21957篇
  2005年   20501篇
  2004年   20066篇
  2003年   18999篇
  2002年   18527篇
  2001年   36366篇
  2000年   36945篇
  1999年   30417篇
  1998年   7883篇
  1997年   6671篇
  1996年   6978篇
  1995年   6636篇
  1994年   6103篇
  1993年   5602篇
  1992年   23005篇
  1991年   22951篇
  1990年   22333篇
  1989年   22102篇
  1988年   20061篇
  1987年   19459篇
  1986年   18500篇
  1985年   17338篇
  1984年   12724篇
  1983年   10750篇
  1982年   5925篇
  1979年   11528篇
  1978年   8136篇
  1977年   6838篇
  1976年   6603篇
  1975年   7271篇
  1974年   8500篇
  1973年   8141篇
  1972年   7658篇
  1971年   7129篇
  1970年   6877篇
  1969年   6308篇
  1968年   5780篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
71.
Maternal and Child Health Journal - Background Prenatal substance use screening is recommended. The 4 P’s Plus screener includes questions on perceived problematic substance use in parents...  相似文献   
72.

Introduction The focus in clinical pharmacy practice is and has for the last 30–35 years been on changing the role of pharmacy staff into service orientation and patient counselling. One way of doing this is by involving staff in change process and as a researcher to take part in the change process by establishing partnerships with staff. On the background of the authors’ widespread action research (AR)-based experiences, recommendations and comments for how to conduct an AR-study is described, and one of their AR-based studies illustrate the methodology and the research methods used. Methodology AR is defined as an approach to research which is based on a problem-solving relationship between researchers and clients, which aims at both solving a problem and at collaboratively generating new knowledge. Research questions relevant in AR-studies are: what was the working process in this change oriented study? What learning and/or changes took place? What challenges/pitfalls had to be overcome? What were the influence/consequences for the involved parts? When to use If you want to implement new services and want to involve staff and others in the process, an AR methodology is very suitable. The basic advantages of doing AR-based studies are grounded in their participatory and democratic basis and their starting point in problems experienced in practice. Limitations Some of the limitations in AR-studies are that neither of the participants in a project steering group are the only ones to decide. Furthermore, the collective process makes the decision-making procedures relatively complex.

  相似文献   
73.
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   
74.
75.
76.
77.
78.
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   
79.
80.
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