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   1269150篇
  免费   95169篇
  国内免费   1606篇
耳鼻咽喉   16382篇
儿科学   41153篇
妇产科学   35109篇
基础医学   190050篇
口腔科学   35124篇
临床医学   118171篇
内科学   248921篇
皮肤病学   27415篇
神经病学   102400篇
特种医学   46855篇
外国民族医学   265篇
外科学   179235篇
综合类   25779篇
现状与发展   3篇
一般理论   570篇
预防医学   105210篇
眼科学   28101篇
药学   92941篇
  7篇
中国医学   2041篇
肿瘤学   70193篇
  2018年   13753篇
  2017年   10523篇
  2016年   11472篇
  2015年   13236篇
  2014年   18217篇
  2013年   27776篇
  2012年   38013篇
  2011年   40370篇
  2010年   23278篇
  2009年   22426篇
  2008年   38056篇
  2007年   40705篇
  2006年   40220篇
  2005年   39367篇
  2004年   37748篇
  2003年   36139篇
  2002年   35056篇
  2001年   56119篇
  2000年   57126篇
  1999年   48158篇
  1998年   13424篇
  1997年   12254篇
  1996年   12669篇
  1995年   11939篇
  1994年   11126篇
  1993年   10412篇
  1992年   38241篇
  1991年   37722篇
  1990年   36487篇
  1989年   35286篇
  1988年   32713篇
  1987年   32053篇
  1986年   30550篇
  1985年   28813篇
  1984年   21961篇
  1983年   19215篇
  1982年   11381篇
  1981年   10333篇
  1979年   20953篇
  1978年   15401篇
  1977年   12799篇
  1976年   11854篇
  1975年   12816篇
  1974年   15598篇
  1973年   15368篇
  1972年   14518篇
  1971年   13557篇
  1970年   12798篇
  1969年   12071篇
  1968年   11238篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The limited contact dynamic compression plate (LC-DCP)   总被引:5,自引:0,他引:5  
Summary To realize the new concept of biological internal fixation the limited contact dynamic compression plate was developed. It minimizes vascular damage to the plated bone segment. It should lead to a more versatile and efficient application of internal fixation using plates.  相似文献   
992.
Desferrioxamine (DFO) metabolism and its pharmacokinetics were studied in a swine model using high-performance liquid chromatography. DFO and three iron-binding metabolites occurred in plasma. Interindividual differences in pharmacokinetics and metabolism were observed. Urine analysis in 4 pigs showed three iron-binding metabolites. The mean percent dose excreted in urine in the form of the parent drug was 45 +/- 10% and 10 +/- 2% (means +/- SD) in the form of metabolites. Of the total amount of the parent drug infused, 3 h after initiation, 87% was in the form of DFO, whereas 13% was present as the DFO-iron III complex which represented 45 mg of urinary iron elimination. The described DFO infusion protocol provides for sufficient DFO to chelate significant amounts of ferric iron in excess of normal levels, thus allowing experimental studies of iron chelation in a variety of disease states.  相似文献   
993.
Between January and June 1988, a survey of 7516 people in aged care facilities in the Auckland region (99.4% response rate) was undertaken to ascertain the extent and provision of care for elderly people requiring ongoing care in order to make comparisons with other centres in New Zealand. Information was gathered about their ability to perform various activities of daily living by staff members who completed a structured precoded and pretested questionnaire for each resident or patient. Overall levels of dependency were also assessed as part of the questionnaire: 13% were assessed as requiring long stay hospital care, 48% had moderate or appreciable dependency, and the remainder had some dependency (23%) or none at all (16%). Almost one quarter (23%) of the 5213 residents in old people's homes were rated as apparently independent. Of people in religious and welfare residential homes, 38% were rated as independent whereas in commercial rest homes 12% of people were classified in this way. This high level of apparent independence in religious and welfare homes is the main aspect in which the Auckland long term care scene is distinct from other regions in the country.  相似文献   
994.
Epitope libraries provide a method to identify peptide ligands for antibodies, receptors or other binding proteins. As such, they provide a powerful tool to rapidly identify lead ligands in the drug discovery process. In an attempt to correlate structural information with the results from peptide screening, we have used NMR spectroscopy of peptide/antibody complexes to demonstrate that core residues identified through a two-stage selection process undergo a larger structural change upon binding antibody than do positions in the peptide amenable to a variety of side chains. The model system used was the M2 monoclonal antibody/Flag? octapeptide epitope system. We have analyzed two peptides: Ac-Asp-Tyr-Lys-Leu-Gly-Asp-Asp-Leu-NH2 (peptide l), which contains several non-core positions randomized, and Ac-Asp-Tyr-Lys-Asp-Asp-Asp-Asp-Leu-NH2 (peptide 2), which closely corresponds to the original Flag? sequence. Enrichment of the peptides with 15N facilitated the investigation by permitting spectral editing of the peptide resonances in the presence of antibody. For peptide 1 the absolute shifts for the free vs. Fab-bound peptide were found to be largest for the amide groups of Asp-1 and Asp-6, in agreement with classification of these residues as critical by the phage display library selection process. For peptide 2 the largest absolute shifts were observed for Asp-1 and Asp-4, with the other aspartic acid residues also showing significant but smaller changes. © Munksgaard 1995.  相似文献   
995.
Background : Malnutrition is very frequent in childhood cancer. Its main cause is inadequate intake for energy demands owing to lack of appetite. Megestrol acetate is a synthetic progestin that has been used for reversing anorexia in adult cancer.
Objectives : To assess megestrol acetate efficacy and side-effects in treating anorexia in childhood cancer.
Methods : Thirty-five children with solid tumours were receiving antitumour therapy. Nutritional assessment was by anthropometry. Megestrol acetate efficacy was assessed by evaluating grade of appetite, energy intake and well-being. Side-effects were evaluated by means of clinical history, physical examination, lipid profile, coagulation tests and cortisol rhythm.
Results : When compared to baseline all the anthropometric measurements increased ( P <0.05) from the first month of megestrol acetate therapy, as well as appetite and energy intake. No significant side-effects were found.
Conclusion : Megestrol acetate therapy is a powerful appetite stimulant which led to weight gain, composed of both fat mass and fat-free mass. Megestrol acetate is well tolerated, with few and mild side-effects. If megestrol acetate therapy is started at the onset of anorexia, the use of more expensive, invasive and complicated techniques of nutritional support may be avoided.  相似文献   
996.
Extracellular single-unit recordings were made in somatosensory cortical barrels of fentanyl-sedated rats. Whiskers were deflected singly or in paired combinations. lontophoretically-applied (−)-baclofen disproportionately reduced weak responses, and phaclofen disproportionately increased them, resulting in more tightly focused or more broadly focused receptive fields, respectively. Both drugs had only minor effects on surround inhibition. In light of previous findings, we conclude that GABAA and GABAB mechanisms both act to enhance spatial contrast, but that the former plays a much greater role in enhancing temporal resolution.  相似文献   
997.
998.
999.
1000.
Clusterlike Headache as a First Sign of Brain Metastases of Lung Cancer   总被引:1,自引:0,他引:1  
Dr.  J. Tajti  MD  PhD ; Dr.  K. Sas  MD ; Dr.  D. Szok  MD ; Dr.  E. Vörös  MD ; Dr.  L. Vécsei  MD  DSc 《Headache》1996,36(4):259-260
We report on a patient with clusterlike headache and multiple brain metastases of lung cancer. Initially, cluster headache was suggested clinically by characteristic symptoms without any focal central nervous system signs. However, magnetic resonance imaging demonstrated multiple brain metastases. It is possible that tumor necrosis factor may have played a role in initiating the clusterlike headache.  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