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   214050篇
  免费   35500篇
  国内免费   2531篇
耳鼻咽喉   5948篇
儿科学   7069篇
妇产科学   3997篇
基础医学   13613篇
口腔科学   3154篇
临床医学   32645篇
内科学   59802篇
皮肤病学   8394篇
神经病学   20662篇
特种医学   8991篇
外国民族医学   45篇
外科学   49008篇
综合类   767篇
现状与发展   72篇
一般理论   85篇
预防医学   11928篇
眼科学   4504篇
药学   5669篇
中国医学   170篇
肿瘤学   15558篇
  2024年   699篇
  2023年   4939篇
  2022年   1651篇
  2021年   4074篇
  2020年   6612篇
  2019年   3045篇
  2018年   8451篇
  2017年   8045篇
  2016年   9255篇
  2015年   9422篇
  2014年   16737篇
  2013年   17840篇
  2012年   8481篇
  2011年   8591篇
  2010年   12501篇
  2009年   16003篇
  2008年   8604篇
  2007年   7008篇
  2006年   9410篇
  2005年   6584篇
  2004年   5926篇
  2003年   4649篇
  2002年   4774篇
  2001年   5923篇
  2000年   5188篇
  1999年   5170篇
  1998年   4515篇
  1997年   4185篇
  1996年   3998篇
  1995年   3866篇
  1994年   2495篇
  1993年   2154篇
  1992年   2806篇
  1991年   2777篇
  1990年   2373篇
  1989年   2469篇
  1988年   2096篇
  1987年   1946篇
  1986年   1928篇
  1985年   1669篇
  1984年   1226篇
  1983年   1162篇
  1982年   967篇
  1981年   835篇
  1980年   731篇
  1979年   927篇
  1978年   703篇
  1977年   750篇
  1975年   650篇
  1972年   642篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
A wide range of vascular disorders can affect the spleen. Although clinical presentation is often nonspecific, early diagnosis and treatment are mandatory in most conditions. Noninvasive imaging techniques are well suited to meet these objectives. Familiarity with normal macroscopic and microscopic vascular anatomy is a prerequisite to understand the pathophysiology of vascular disorders of the spleen. This article deals with diseases of the splenic vasculature (aneurysms, arteriovenous fistula, splenic vein thrombosis, collateral circulation in portal hypertension) as well as vascular disorders affecting the splenic parenchyma (splenic infarct, Gamna-Gandy bodies). Primary vascular tumors and tumor-like conditions of the spleen will be discussed very briefly.  相似文献   
995.
996.
This study retrospectively compares patients who underwent outpatient transvaginal follicle aspiration with either a propofol- or methohexital-based intravenous sedation technique. Data collected from patient charts (n = 212) over a 46-month period were analyzed to determine the effects of each sedation technique on procedure and recovery times, number of retrieved ova, as well as rates of nausea, fertilization, cleavage, pregnancy, and delivery. All patients were included in the study, regardless of age or diagnosis. procedure time was lower in the propofol group (51 t 18 min) than in the methohexital group (61 I 20 min) (p > 0.01). Patients in the methohexital group (139 2 51 min) spent more time in the recovery room than did those in the propofol group (71 ? 34 min) (p > 0.01). The nausea rates were significantly lower in the propofol group compared with the methohexital group (1.9% vs. 14.4%, respectively) (p > 0.02). Fertilization rate in the propofol group was 77.7% and was 62.9% in the methohexital group (p > 0.01). The numbers of retrieved ova and the cleavage rates were similar in both groups. The rate of pregnancy in patients sedated with propofol (46.1%) was higher than the methohexital group (26.9%) (p > 0.02). Delivery rate was 38.5% in the propofol group and 20.6% in the methohexital group (p > 0.02). In summary, propofol intravenous sedation for transvaginal follicle aspiration was associ- ated with an improved outcome. Pregnancy and delivery rates were higher while nausea, an unpleasant side effect, was sharply reduced.  相似文献   
997.
To investigate the influence of glucocorticosteroid therapy on the neonatal blood count, the haematologic data of 68 preterm and term infants, who had received a single dose of 1 mg dexamethasone i.v., were reviewed. White blood cell (WBC) count and platelet count increased after steroid therapy. The increase in WBCs was associated with an increase in the number of neutrophilic granulocytes, whereas the number of eosinophils decreased. We conclude that glucocorticosteroids after the neonatal blood count and influence its value as a diagnostic marker for bacterial infections.  相似文献   
998.
Plasminogen activators tPA and uPA are involved in tissue remodeling, but their role in bone growth is undefined. Mice lacking tPA and uPA show increased bone formation and bone mass. The noncollagenous components of bone matrix are also increased, probably from defective degradation. This study underlines the importance of controlled bone matrix remodeling for normal endochondral ossification. INTRODUCTION: Proteolytic pathways are suggested to play a role in endochondral ossification. To elucidate the involvement of the plasminogen activators tPA and uPA in this process, we characterized the long bone phenotype in mice deficient in both tPA and uPA (tPA-/-:uPA-/-). MATERIALS AND METHODS: Bones of 2- to 7-day-old tPA-/-:uPA-/- and wild-type (WT) mice were studied using bone histomorphometry, electron microscopy analysis, and biochemical assessment of bone matrix components. Cell-mediated degradation of metabolically labeled bone matrix, osteoblast proliferation, and osteoblast differentiation, both at the gene and protein level, were studied in vitro using cells derived from both genotypes. RESULTS: Deficiency of the plasminogen activators led to elongation of the bones and to increased bone mass (25% more trabecular bone in the proximal tibial metaphysis), without altering the morphology of the growth plate. In addition, the composition of bone matrix was modified in plasminogen activator deficient mice, because an increased amount of proteoglycans (2x), osteocalcin (+45%), and fibronectin (+36%) was detected. Matrix degradation assays showed that plasminogen activators, by generating plasmin, participate in osteoblast-mediated degradation of the noncollagenous components of bone matrix. In addition, proliferation of primary osteoblasts derived from plasminogen activator-deficient mice was increased by 35%. Finally, osteoblast differentiation and formation of a mineralized bone matrix were enhanced in osteoblast cultures derived from tPA-/-:uPA-/- mice. CONCLUSIONS: The data presented indicate the importance of the plasminogen system in degradation of the noncollagenous components of bone matrix and suggest that the accumulation of these proteins in bone matrix--as occurs during plasminogen activator deficiency--may in turn stimulate osteoblast function, resulting in increased bone formation.  相似文献   
999.
1000.
Summary The validity of clinical studies on shunt-treated hydrocephalic patients is often hindered by inhomogeneity of the patient population examined, technical devices used, or by other specific factors. In an effort to introduce a homogeneous clinical study on hydrocephalic patients 66 hydrocephalic newborns and infants have been treated exclusively with CORDIS Orbis-Sigma Valve (OSV) System (CORDIS Corporation, Miami, USA) in 1990–1995. The results are compared with an equivalent group of 53 children treated with CODMAN Holter Valve (HV) System (CODMAN Inc., Randolph, USA) during a similar 5-year-period (e.g., 1986–1991). Searching for different reasons of shunt insufficiency in both groups demonstrates a more than double risk of shunt complication for ventriculo-atrial HV treated patients (VA-HV) in comparison with those treated ventriculo-peritoneally with OSV System (VP-OSV): 4.22 versus 1.98 mean surgical procedures per person. The different revision and survival rates are discussed and specific problems are mentioned.  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