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   1994篇
  免费   166篇
  国内免费   66篇
耳鼻咽喉   36篇
儿科学   96篇
妇产科学   11篇
基础医学   160篇
口腔科学   51篇
临床医学   253篇
内科学   211篇
皮肤病学   14篇
神经病学   29篇
特种医学   89篇
外科学   161篇
综合类   492篇
预防医学   242篇
眼科学   11篇
药学   146篇
  2篇
中国医学   125篇
肿瘤学   97篇
  2024年   5篇
  2023年   15篇
  2022年   38篇
  2021年   49篇
  2020年   51篇
  2019年   30篇
  2018年   30篇
  2017年   52篇
  2016年   36篇
  2015年   52篇
  2014年   96篇
  2013年   127篇
  2012年   162篇
  2011年   177篇
  2010年   185篇
  2009年   152篇
  2008年   173篇
  2007年   151篇
  2006年   89篇
  2005年   81篇
  2004年   64篇
  2003年   60篇
  2002年   25篇
  2001年   40篇
  2000年   19篇
  1999年   14篇
  1997年   9篇
  1996年   8篇
  1995年   8篇
  1992年   5篇
  1990年   6篇
  1989年   10篇
  1988年   10篇
  1987年   17篇
  1986年   9篇
  1985年   12篇
  1984年   13篇
  1982年   7篇
  1981年   7篇
  1980年   9篇
  1979年   11篇
  1977年   4篇
  1974年   5篇
  1965年   5篇
  1963年   4篇
  1958年   5篇
  1957年   7篇
  1956年   9篇
  1955年   7篇
  1954年   8篇
排序方式: 共有2226条查询结果,搜索用时 6 毫秒
1.
ABSTRACT. Hultcrantz R, Angelin B, Einarsson K, Friman L (Departments of Internal Medicine and Roentgenology, Serafimer Hospital, and Department of Internal Medicine, Huddinge University Hospital, Karolinska Institute, Stockholm, Sweden). Spontaneous regression of Budd-Chiari syndrome (hepatic venous occlusion) in a young female. Acta Med Scand 1987; 221:503–7. A case of occlusion of the hepatic veins in an 18-year-old girl is presented. The onset was sudden with massive ascites and markedly impaired general condition. The diagnosis was based on liver biopsy and angiograms of the caval and hepatic veins as well as of the celiac artery. No predisposing factors could be found. The patient was treated conservatively with laparo-centesis and diuretics. Clear improvement was seen after two weeks, and after four weeks she had no ascites and could be discharged. All liver function tests were then normalized. After three months, all diuretics could be withdrawn, and in the following 11 years she has remained completely recovered. The case illustrates that also widespread thrombi of the hepatic veins may sometimes rapidly dissolve spontaneously, with apparent total reconstitution of hepatic function. This case is unusual since previously reported cases have had high mortality rates and, in surviving cases, operative procedures or large doses of diuretics have been required to control the ascites.  相似文献   
2.
AIM: To evaluate the cause of elevated prostate-specific antigen (PSA) in patients with transrectal needle biopsy negative for prostate cancer. METHODS: Serum PSA concentration, prostate volume, and pathologic findings were examined in 223 patients with negative biopsy for prostate cancer. The degree of prostate inflammation was determined by the extent and degree of inflammation shown by biopsy specimens and is expressed as an inflammation score (range: 0-36). RESULTS: A significant correlation was found between PSA concentration and prostate total volume (P=0.0001). Prostate chronic inflammation showed no correlation with PSA concentration (P=0.485, F=0.488). After allocating patients to normal PSA (4 ng/mL) groups, we found that serum PSA concentrations in both groups were predominantly affected by prostate total volume. CONCLUSIONS: An increase in prostate volume appears to be the major contributor to a high serum PSA concentration in patients with negative biopsy for prostate cancer. However, in contrast to previous reports, there was no correlation between the degree of prostate chronic inflammation and serum PSA concentrations.  相似文献   
3.
NATURE AND HEALING OF TIBIAL SHAFT FRACTURES IN ALCOHOL ABUSERS   总被引:3,自引:1,他引:2  
Alcohol abuse is associated with an increased risk of osteopeniaand fractures. Previous histomorphometric studies on iliac crestbone have found decreased bone formation and increased boneresorption in alcohol abusers but it has not been establishedwhether alcohol abuse has any effect on the anatomical locationor the healing time of tibial shaft fractures. We studied, retrospectively,199 adult male patients hospitalized for isolated tibial shaftfracture in the city of Malmö, Sweden, between 1980 and1990. Forty-nine of the patients had earlier been registeredat the Department of Alcohol Diseases and were judged to beproblem drinkers. Abusers sustained their tibial shaft fracturesmore often by falling at ground level (P<0.0001) or froma higher level (P=0.009) and the fractures were more often obliquethan transverse (P=0.002) as compared with non-abusers. Healingtime was impaired in abusers who had sustained a transversefracture (P=0.035), but no difference was observed in healingtime in those with an oblique fracture. We found no differencebetween the abusers and the non-abusers regarding duration ofhospital stay, fracture location, amount of displacement, occurrenceof open fractures or the rate of complications.  相似文献   
4.
目的:鉴定并研究半夏AP2/ERF转录因子的功能,为推进半夏品种的遗传改良提供理论依据。方法:该文基于半夏三代转录组数据鉴定了半夏中AP2/ERF家族成员,并对其进行系统的生物信息学分析,同时利用实时荧光定量聚合酶链式反应(Real-time PCR)检测半夏AP2/ERF在不同组织及不同胁迫条件下的表达情况。结果:通过转录组数据共筛选出8个全长AP2/ERF转录因子家族成员,归为AP2、ERF和DREB 3个亚家族;半夏AP2/ERF的氨基酸数目为251~512个,等电点为5.29~11.72,不稳定指数为45.90~82.41,且主要定位于细胞核中;半夏AP2/ERF基因的结构域和Motifs相对保守。组织特异性表达模式分析显示,半夏AP2/ERF基因在不同组织部位中具有不同的表达模式,且主要在叶中表达。逆境胁迫应答分析表明,PtERF1主要响应NaCl的胁迫诱导;PtERF2和PtERF4在低温和聚乙二醇(PEG)胁迫下表达量均有较大幅度的上调;PtERF3同时响应低温和NaCl两种逆境的诱导;PtERF5同时响应高温、低温、NaCl、PEG胁迫诱导;PtERF7在高温胁迫下表达...  相似文献   
5.
Apoptosis is a critical cellular event during several stages of neuronal development. Recently, we have shown that biotinylated annexin V detects apoptosis in vivo in various cell lineages of a wide range of species by binding to phosphatidylserines that are exposed at the outer leaflet of the plasma membrane. In the present study, we tested the specificity by which annexin V binds apoptotic neurons, and subsequently investigated developmental cell death in the central and peripheral nervous system of early mouse embryos at both the cellular and histological level, and compared the phagocytic clearance of apoptotic neurons with that of apoptotic mesodermal cells. Our data indicate: (i) that biotinylated annexin V can be used as a sensitive marker that detects apoptotic neurons, including their extensions at an early stage during development; (ii) that apoptosis plays an important part during early morphogenesis of the central nervous system, and during early quantitative matching of brain-derived neurotrophic factor and neurotrophic factor 3 responsive postmitotic large clear neurons in the peripheral ganglia with their projection areas; and (iii) that apoptotic neurons are removed by a process that differs from classical phagocytosis of non-neuronal tissues.  相似文献   
6.
目的 观察心脏跳动下心内直视手术对心肌的保护效应。方法 选择常温下心脏不停跳心内直视手术患者 2 0例为实验组 ,浅低温心脏停跳下手术患者 2 0例为对照组。观察2组患者磷酸肌酸激酶 (CK -MB)、心肌细胞凋亡及心肌细胞超微结构的变化。结果 术后 12h及 2 4h ,实验组CK -MB低于对照组 ,术后 4 8h 2组均恢复正常 ;实验组心肌细胞凋亡率和心肌细胞超微结构破坏程度均明显低于对照组。结论 常温下心脏不停跳心内直视手术仍存在一定程度的心肌损伤 ,但较浅低温心脏停跳术减轻 ,对心肌有一定保护作用  相似文献   
7.
为规范临床试验数据管理,简化程序并减少数据统计分析过程中的错误来源,我们编制了一些特定的SAS宏程序,可以直接输出临床试验四格表指标统计分析报表。  相似文献   
8.
2005年吉林省农村生活饮用水监测县水质分级评价   总被引:6,自引:0,他引:6  
目的掌握吉林省农村生活饮用水基本状况,并为农村改水工作提供科学的依据。方法依据“农村实施《生活饮用水卫生标准》准则”,对2005年吉林省农村生活饮用水监测县的枯水期和丰水期水质分别进行分级评价。结果100个监测水点中,枯水期安全饮用水监测点数34个,非安全饮用水监测点数66个;丰水期安全饮水的监测点数66个,非安全饮用水监测点是34个。结论细菌总数和大肠菌群这两项微生物学指标是影响本省农村饮水水质的重要因素。必须进行适当净化和消毒处理,加强对饮水水源的卫生防护,以保障农村居民的身体健康。  相似文献   
9.
临床试验数据采集与报告文件设计制作的技术规程   总被引:1,自引:0,他引:1  
临床试验数据采集与报告文件的设计和制作对保证试验数据的质量与完整性至关重要。参照临床试验数据管理规范 (GCP)并结合具体实践经验制订本规程。设计规程包括与方案设计同步、文件格式、问题和提示、冗余数据、数据记录指南、标准化、版本管理与培训 ;印制规程包括审批、印制说明书以及厂商选择。  相似文献   
10.
为规范临床试验数据管理,简化程序并减少数据统计分析过程中的错误来源,我们编制了一些特定的SAS宏程序,可以直接输出临床试验正态分布的定量指标统计分析报表。  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