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   63546篇
  免费   5444篇
  国内免费   3287篇
耳鼻咽喉   599篇
儿科学   814篇
妇产科学   907篇
基础医学   8119篇
口腔科学   1218篇
临床医学   7988篇
内科学   10074篇
皮肤病学   880篇
神经病学   3721篇
特种医学   2662篇
外国民族医学   37篇
外科学   6929篇
综合类   7814篇
现状与发展   7篇
一般理论   18篇
预防医学   4559篇
眼科学   1671篇
药学   6110篇
  44篇
中国医学   2699篇
肿瘤学   5407篇
  2024年   170篇
  2023年   898篇
  2022年   2288篇
  2021年   3120篇
  2020年   2131篇
  2019年   2056篇
  2018年   2208篇
  2017年   1872篇
  2016年   2043篇
  2015年   2834篇
  2014年   3518篇
  2013年   3354篇
  2012年   5275篇
  2011年   5445篇
  2010年   3360篇
  2009年   2748篇
  2008年   3730篇
  2007年   3586篇
  2006年   3366篇
  2005年   3069篇
  2004年   2227篇
  2003年   2109篇
  2002年   1842篇
  2001年   1271篇
  2000年   1268篇
  1999年   1221篇
  1998年   709篇
  1997年   730篇
  1996年   587篇
  1995年   486篇
  1994年   408篇
  1993年   286篇
  1992年   371篇
  1991年   265篇
  1990年   245篇
  1989年   208篇
  1988年   163篇
  1987年   148篇
  1986年   123篇
  1985年   95篇
  1984年   60篇
  1983年   66篇
  1982年   36篇
  1981年   37篇
  1980年   22篇
  1979年   38篇
  1978年   19篇
  1974年   23篇
  1973年   19篇
  1969年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Intraductal papillary mucinous tumor (IPMT) of the pancreas, a lesion consisting of mucin-producing cells with neoplastic potential, is characterized by duct ectasia, mucin hypersecretion, often extensive papillary intraductal growth, varying degrees of cytologic atypia, and relatively indolent growth. The clinical presentation of IPMT of the pancreas is characterized by chronic or recurrent attacks of abdominal discomfort often in association with low level pancreatic enzyme elevations. Less commonly these lesions may be detected as asymptomatic radiographic abnormalities. Interestingly, a case of a minute IPMT (2 mm in height and 7 mm in length, adenoma) in the main pancreatic duct presenting with acute pancreatitis in a 55 year-old man has been reported in the Japanese literature. Recently, we also experienced a case of a minute IPMT in a branch pancreatic duct causing repeated bouts of acute pancreatitis in a 75 year-old man. A filling defect at the neck of the main pancreatic duct seen on an endoscopic retrograde pancreatogram performed after recovery of the second attack of acute pancreatitis led the patient to undergo an exploratory laparotomy. After a near-total pancreatectomy was carried out, a minute (3 x 7 mm) IPMT of borderline malignancy was discovered in a branch duct at the head portion near the pancreatic neck without any lesions in the main pancreatic duct. Surprisingly, despite the resective surgery the patient died of carcinomatosis 8.5 months after the operation. We herein report a case of a minute but aggressive IPMT of the pancreas with a review of the literature.  相似文献   
102.
103.
Summary [E35], an extranuclear mutant of Neurospora crassa has all the phenotypic characteristics of the stopper mutants (De Vries et al. 1980). In the present work, the mitochondrial DNA as well as the mitochondrial translation products are characterized further. The primary mutational event appears to have been the deletion of about 4 kbp from the wild-type genome. Moreover, after prolonged vegetative growth the mutant accumulates an 8-m circular mtDNA, which was demonstrated both by electronmicroscopy and by restriction enzyme analysis. Hence, the mutant contains two populations of aberrant mitochondrial DNA, the smaller of which is an amplification of the rRNA-tRNA part of the larger. We propose that the primary deletion has generated a signal in the larger DNA which can cause premature termination of replication at the deletion site, and subsequent circularization of the unfinished daughter molecule. Finally, the deleted part may contain a determinant for synthesis of a protein of 11 kDal. The function of this protein, which is not a subunit of the F0 ATPase, is not yet known.Abbreviations (k)bp (kilo)basepairs - kDal kilodalton - mt mitochondrial  相似文献   
104.
PurposeDissection after plain balloon angioplasty is required to achieve adequate luminal area; however, it is associated with a high risk of vascular events. This study aimed to examine the relationship between non-flow limiting coronary dissections and subsequent lumen loss and long-term clinical outcomes following successful drug-coated balloon (DCB) treatment of de novo coronary lesions.Materials and MethodsA total of 227 patients with good distal flow (Thrombolysis in Myocardial Infarction flow grade 3) following DCB treatment were retrospectively enrolled and stratified according to the presence or absence of a non-flow limiting dissection. The primary endpoint was late lumen loss (LLL) at 6-month angiography, and the secondary endpoint was target vessel failure (TVF, a composite of cardiac death, target vessel myocardial infarction, target vessel revascularization, and target vessel thrombosis).ResultsThe cohort consisted of 95 patients with and 132 patients without a dissection. There were no between-group differences in LLL (90.8%) returning for angiography at 6 months (0.05±0.19 mm in non-dissection and 0.05±0.30 mm in dissection group, p=0.886) or in TVF (6.8% in non-dissection and 8.4% in dissection group, p=0.799) at a median follow-up of 3.4 years. In a multivariate analysis, the presence of dissection and its severity were not associated with LLL or TVF. Almost dissections (93.9%) were completely healed, and there was no newly developed dissection at 6-month angiography.ConclusionThe presence of a dissection following successful DCB treatment of a de novo coronary lesion may not be associated with an increased risk of LLL or TVF (Impact of Drug-coated Balloon Treatment in de Novo Coronary Lesion; NCT04619277).  相似文献   
105.
Metabolic syndrome is a worldwide health problem, and obesity is closely related to type 2 diabetes, cardiovascular disease, hypertension, and cancer. According to WHO in 2018, the prevalence of obesity in 2016 tripled compared to 1975. D. morbifera reduces bad cholesterol and triglycerides levels in the blood and provides various antioxidant nutrients and germicidal sub-stances, as well as selenium, which helps to remove active oxygen. Moreover, D. morbifera is useful for treating cardiovascular diseases, hypertension, hyperlipidemia, and diabetes. Therefore, we study in vivo efficacy of D. morbifera to investigate the prevention effect of obesity and cholesterol. The weight and body fat were effectively reduced by D. morbifera water (DLW) extract administration to high-fat diet-fed C57BL/6 mice compared to those of control mice. The group treated with DLW 500 mg∙kg−1∙d−1 had significantly lower body weights compared to the control group. In addition, High-density lipoprotein (HDL) cholesterol increased in the group treated with DLW 500 mg∙kg−1∙d−1. The effect of DLW on the serum lipid profile could be helpful to prevent obesity. DLW suppresses lipid formation in adipocytes and decreases body fat. In conclusion, DLW can be applied to develop anti-obesity functional foods and other products to reduce body fat.  相似文献   
106.
Prevention Science - This study is a qualitative analysis of facilitators and barriers in the dissemination of Family Check-Up (FCU), a U.S.-developed preventive intervention in Sweden. The FCU is...  相似文献   
107.
108.
109.
以硅酸钠、氯化铁为原料制备聚硅氯化铁(简称PFSC)混凝剂。重点考察Fe/SiO2摩尔比对PFSC混凝效果的影响。结果表明:PFSC的混凝效果优于聚硅酸(PS),且Fe/SiO2摩尔比对PFSC的混凝效果有较大的影响。确定Fe/SiO2摩尔比为1:1.5时,其混凝效果最佳,且用药量少而范围广。为制备高效的PFSC提供了优化条件。  相似文献   
110.
(1)目的 总结320例胆管术后,经T管窦道纤维胆管镜治疗残余结石的经验。(2)方法 对320例胆管术后残余结石病人行纤维胆管镜取石,分析其临床表现并予以随访。(3)结果 结石取净287例,失败33例,(4)结论 纤维胆管镜对于术后胆管残余结石的治疗起着重要作用。  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