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   33888篇
  免费   1929篇
  国内免费   339篇
耳鼻咽喉   553篇
儿科学   386篇
妇产科学   466篇
基础医学   5593篇
口腔科学   885篇
临床医学   2701篇
内科学   6410篇
皮肤病学   1323篇
神经病学   2457篇
特种医学   2335篇
外国民族医学   1篇
外科学   4161篇
综合类   227篇
一般理论   5篇
预防医学   1592篇
眼科学   594篇
药学   3333篇
中国医学   444篇
肿瘤学   2690篇
  2024年   23篇
  2023年   244篇
  2022年   779篇
  2021年   1242篇
  2020年   564篇
  2019年   800篇
  2018年   982篇
  2017年   804篇
  2016年   1161篇
  2015年   1544篇
  2014年   1806篇
  2013年   2068篇
  2012年   3088篇
  2011年   3031篇
  2010年   1743篇
  2009年   1527篇
  2008年   2102篇
  2007年   1901篇
  2006年   1700篇
  2005年   1575篇
  2004年   1208篇
  2003年   1059篇
  2002年   910篇
  2001年   796篇
  2000年   726篇
  1999年   522篇
  1998年   230篇
  1997年   152篇
  1996年   131篇
  1995年   93篇
  1994年   102篇
  1993年   83篇
  1992年   148篇
  1991年   153篇
  1990年   172篇
  1989年   147篇
  1988年   130篇
  1987年   125篇
  1986年   104篇
  1985年   69篇
  1984年   48篇
  1983年   44篇
  1982年   33篇
  1981年   41篇
  1980年   18篇
  1979年   23篇
  1978年   23篇
  1977年   24篇
  1975年   26篇
  1970年   23篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
BACKGROUND: Complete correction of atrioventricular septal defect (AVSD) associated with tetralogy of Fallot (TOF) has been reported to account for an increased surgical risk. Impaired right ventricular function after classic transventricular repair, residual outflow tract stenosis, and incompetence of the pulmonary or atrioventricular valves are considered to be essential factors affecting the results. METHODS: From 3/95 to 6/98 six consecutive patients with AVSD and TOF underwent repair (age 18 months to 7.3 years) using a combined transatrial-transpulmonary approach. RV outflow tract balloon dilatation preceded transatrial correction in 4 patients. Pulmonary annulotomy but not transanular patching was necessary in 4 cases. The septal defects were closed by two separate patches using a Dacron patch with short depth and anterior extension for the ventricular component. RESULTS: All patients survived and had stable sinus rhythm. Echocardiography demonstrated mild, but hemodynamically insignificant mitral regurgitation in two and tricuspid regurgitation in four patients. Right ventricle to pulmonary artery gradients ranged from 5 to 35 mmHg (mean 24.2 mmHg) without progression. During follow-up ranging from 4 months to 3.5 years (mean 16.8 months) no reoperation was necessary. CONCLUSIONS: The transatrial-transpulmonary approach for correction of AVSD with TOF contributes to improved results after repair of this rare combination of defects.  相似文献   
122.
Construction of a bioengineered cardiac graft   总被引:19,自引:0,他引:19  
OBJECTIVES: Currently available graft materials for repair of congenital heart defects cause significant morbidity and mortality because of their lack of growth potential. An autologous cell-seeded graft may improve patient outcomes. We report our initial experience with the construction of a biodegradable graft seeded with cultured rat or human cells and identify their 3-dimensional growth characteristics. METHODS: Fetal rat ventricular cardiomyocytes, stomach smooth muscle cells, skin fibroblasts, and adult human atrial and ventricular cardiomyocytes were isolated and cultured in vitro. These cells were injected into or laid onto biodegradable gelatin meshes, and their rate of proliferation and spatial location within the mesh was evaluated by using a cell counter and histologic analysis. RESULTS: Rat cardiomyocytes, smooth muscle cells, and fibroblasts demonstrated steady proliferation over 3 to 4 weeks. The gelatin mesh was slowly degraded, but this process was most rapid after seeding with fibroblasts. Human atrial cardiomyocytes proliferated within the gelatin meshes but at a slower rate than that of fetal rat cardiomyocytes. Human ventricular cardiomyocytes survived within the gelatin mesh matrix but did not increase in number during the 2-week duration of evaluation. Grafts seeded with rat ventricular cells exhibited spontaneous rhythmic contractility. All cell types preferentially migrated to the uppermost surface of each graft and formed a 300- to 500-microm thick layer. CONCLUSIONS: Fetal rat ventricular cardiomyocytes, gastric smooth muscle cells, skin fibroblasts, and adult human atrial cardiomyocytes can grow in a 3-dimensional pattern within a biodegradable gelatin mesh. Similar autologous cell-seeded constructs may eventually be applied to repair congenital heart defects.  相似文献   
123.
OBJECTIVE: To describe what pediatric primary care providers involved in the Pediatric Research in Office Settings (PROS) research network think are important yet inadequately addressed questions in pediatric primary care research. METHODS: A total of 1785 pediatric primary care providers in the PROS network were asked what they thought were important yet inadequately addressed areas of primary care research. We used a single, open-ended question in a mail survey. Written answers to this question were analyzed by qualitative methods to determine the main themes of interest to pediatric primary care providers. RESULTS: Overall survey response rate was 48.7%; the open-ended question yielded 1109 individual answers. Six lines of inquiry were identified as being important to these providers: (1) effective counseling techniques to use in anticipatory guidance; (2) strategies to prevent and treat obesity; (3) the effectiveness of well-child care; (4) ongoing management of patients with attention-deficit/hyperactivity disorder; (5) the role of the primary care provider in caring for children with mental health needs; and (6) optimal organization of office practices. CONCLUSIONS: The translation of research into practice may be improved by a better understanding of the needs and interests of those who see pediatric patients in the primary care setting.  相似文献   
124.
125.
126.
Differentiation of abdominal masses detected on prenatal ultrasound is difficult and requires careful characterization of the mass and precise localization. Differentiation is required in order to distinguish benign from potentially malignant conditions. We describe a case of fetus‐in‐fetu with pre and postnatal imaging.  相似文献   
127.
128.
129.
Grape seed is an important natural bioactive product with various health benefits. Interstitial cells of Cajal (ICCs) are pacemaker cells in the gastrointestinal (GI) tract. The present study investigated the effects of grape seed powder (GSP) on ICC properties and GI motility. GSP depolarized the pacemaker potentials of ICCs in a dose‑dependent manner. Y25130 or SB269970 slightly inhibited GSP‑induced effects. However, Y25130 and SB269970 together completely blocked GSP-induced effects. In the presence of inhibitors of protein kinase C, protein kinase A, or mitogen-activated protein kinase, GSP‑induced ICC depolarization was inhibited. GSP increased the intestinal transit rate in normal mice and in mice with acetic acid-induced GI motility disorder. In addition, the levels of motilin and substance P were elevated after GSP dosing. These results demonstrate that GSP can regulate GI motility, and therefore, it is a potential therapeutic agent for treating GI motility disorders.  相似文献   
130.
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