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   537篇
  免费   37篇
  国内免费   22篇
耳鼻咽喉   2篇
儿科学   27篇
妇产科学   11篇
基础医学   60篇
口腔科学   11篇
临床医学   59篇
内科学   58篇
神经病学   67篇
特种医学   32篇
外科学   122篇
综合类   9篇
预防医学   56篇
眼科学   6篇
药学   65篇
肿瘤学   11篇
  2021年   8篇
  2019年   5篇
  2018年   8篇
  2017年   3篇
  2016年   9篇
  2015年   5篇
  2014年   12篇
  2013年   19篇
  2012年   20篇
  2011年   18篇
  2010年   15篇
  2009年   8篇
  2008年   32篇
  2007年   35篇
  2006年   24篇
  2005年   19篇
  2004年   40篇
  2003年   40篇
  2002年   26篇
  2001年   20篇
  2000年   16篇
  1999年   18篇
  1998年   12篇
  1997年   5篇
  1996年   8篇
  1995年   8篇
  1994年   6篇
  1993年   4篇
  1992年   8篇
  1991年   10篇
  1990年   11篇
  1989年   10篇
  1988年   9篇
  1987年   5篇
  1986年   10篇
  1985年   10篇
  1984年   3篇
  1983年   6篇
  1981年   5篇
  1979年   8篇
  1978年   10篇
  1975年   6篇
  1974年   3篇
  1973年   4篇
  1972年   4篇
  1971年   4篇
  1970年   5篇
  1969年   3篇
  1967年   5篇
  1964年   2篇
排序方式: 共有596条查询结果,搜索用时 9 毫秒
1.
Delta hepatitis virus infection in China   总被引:1,自引:0,他引:1  
To assess the prevalence, epidemiological features and prognostic implications of hepatitis D (Delta) in Sichuan Province, The People's Republic of China, 649 sera (515 from HBsAg positive patients and 134 from HBsAg negative subjects) were tested by radioimmunoassay (RIA) for antibody to the hepatitis D virus (anti-HD). Forty-seven sera (7.2%) showed some degree of reactivity. Serial dilutions of these sera indicated that prozoning was not responsible for the equivocal results. Thirty-four of the 47 sera were submitted under code to a second laboratory for independent analysis. According to those results anti-HD antibodies were detected in four of these sera. The overall prevalence of anti-HD in the HBsAg positive patients therefore was 0.8% (4/515). On the basis of clinical, biochemical and histological data 427 HBsAg positive sera were further divided into acute Type B hepatitis, chronic Type B hepatitis, healthy carrier state and hepatocellular carcinoma (HCC) subgroups. Two of 65 (3.1%) anti-HD positive sera belonged to the acute Type B hepatitis group; one of 104 (0.9%), the chronic Type B hepatitis group and one of 246 (0.4%), the healthy carrier group. No antibody was detected in sera from 12 HBsAg positive HCC patients. All HBsAg negative patients were negative for anti-HD antibody. The results of this study indicate that despite a high prevalence of hepatitis B virus infection, positive serology for delta virus is uncommon in Sichuan Province, The People's Republic of China.  相似文献   
2.
R Gray  R Hills  R Stowe 《Annals of oncology》2003,14(9):1338-1339
This issue of Annals of Oncology sees a report of a trial bythe Italian INTACC intergroup comparing folinic acid-modulatedfluorouracil, combined with levamisole, with fluorouracil andlevamisole alone [1]. This large trial (n = 1703) adds importantlyto our knowledge of the value of folinic acid in the fluorouracil/folinicacid (FUFA) chemotherapy combination, which is now widely acceptedas the standard regimen in colorectal cancer [2]. No statisticallysignificant differences in terms of disease-free survival oroverall survival were found from modulating the action of fluorouracilwith folinic acid. However, the absence of a statistically significantdifference does not of course establish lack of benefit. Therewere fewer deaths (32%  相似文献   
3.
4.
The effectiveness of a single preinduction intravenous (IV) bolus of esmolol in blunting hemodynamic responses to rapid sequence induction and tracheal intubation was evaluated. In a randomized double-blind study, 32 ASA I and II healthy patients scheduled for surgery were monitored with electrocardiography (EKG) lead V5, arterial cannulation, and impedance cardiography. After preoxygenation and a priming dose of vecuronium (0.01 mg/kg), patients received either saline (n = 12), esmolol 100 mg (n = 10), or esmolol 200 mg (n = 10) as an IV bolus (20 ml volume). This procedure was immediately followed by a 5 ml IV saline flush, cricoid pressure, thiopental sodium 5 mg/kg, and succinylcholine 1.5 mg/kg. Patients receiving 200 mg of esmolol had a 50% reduction in the usual tachycardia associated with induction and a greater decline in systolic blood pressure (SP) (by 50%) prior to intubation as compared with the placebo group (p less than 0.05). The increase in diastolic blood pressure (DP) and the reduction in stroke volume (SV) produced by induction and intubation were similar in all the groups. Plasma norepinephrine levels at 1.5 minutes after intubation increased in the esmolol groups about 130% above that measured in the placebo group. This finding was associated with a more gradual return of peripheral resistance to baseline following tracheal intubation. However, both doses of esmolol effectively attenuated heart rate (HR), SP, and rate pressure product (RPP) increases (p less than 0.05 vs placebo) produced by laryngoscopy and tracheal intubation.  相似文献   
5.
Archives of Sexual Behavior - Although men who have sex with men (MSM) within rural communities are disproportionately impacted by HIV, limited HIV research and programmatic resources are directed...  相似文献   
6.
This paper reports the findings of an evaluation (funded by the Department of Health) of six Communication Aid Centres established in 1983. The evaluation was undertaken to assess the effectiveness of these Centres in meeting their set objectives, and to examine service costs and client satisfaction. The findings show that the work of each Centre was effective in meeting its stated objectives, but that the work of individual Centres reflected its own specialised interests. Two problems with current funding arrangements were highlighted. First, the need to replace the original funding by locally based finance, and second, the funding of communication aids for clients. The findings also show that the specialist service provided by these Centres can be managed at costs per person assessed at, or below, non-specialist services in health districts. Client satisfaction with the services provided by the Centres was high.  相似文献   
7.
8.
BACKGROUND: Falls from balconies and windows are an important cause of childhood injury. This study investigated the circumstances around such falls and attempted to identify possible measures for their prevention. POPULATION: Children <15 years living in Dallas County, Texas. METHODS: Each child treated because of a fall from a building in 1997-99 had information about the injury collected, and a parent was contacted to obtain further information. For apartment related falls, an attempt was made to visit the apartment to measure windows and balcony rails. RESULTS: Ninety eight children were injured in falls from buildings during the three year period; 39 (40%) were admitted to hospital. Seventy five of the falls (77%) involved apartments, and most occurred around noon or evening meal times. Among apartment falls, 39 (52%) fell from windows, 34 (45%) from balconies, and two (3%) from unknown sites. For more than two thirds of balcony related falls, the child fell from between the balcony rails, all of which were spaced more than 4 inches (10 cm) apart. On-site measurement showed the rails were an average of 7.5 inches (19 cm) apart; all of these apartments were built before 1984. For more than two thirds of window related falls, the window was situated within 2 feet (61 cm) of the floor. CONCLUSIONS: Two factors are important in falls from apartment windows and balconies: balcony rails more than 4 inches (10 cm) apart, and windows positioned low to the floor. Current building codes do not apply to older apartments, where most of these falls occurred. Nevertheless, these factors may be amenable to environmental modifications that may prevent most of these falls.  相似文献   
9.
BACKGROUND: The noble gas xenon (Xe) has been used as an inhalational anesthetic agent in clinical trials with little or no physiologic side effects. Like nitrous oxide, Xe is believed to exert minimal unwanted cardiovascular effects, and like nitrous oxide, the vapor concentration to achieve 1 minimum alveolar concentration (MAC) for Xe in humans is high, i.e., 70-80%. In the current study, concentrations of up to 80% Xe were examined for possible myocardial effects in isolated, erythrocyte-perfused guinea pig hearts and for possible effects on altering major cation currents in isolated guinea pig cardiomyocytes. METHODS: Isolated guinea pigs hearts were perfused at 70 mm Hg via the Langendorff technique initially with a salt solution at 37 degrees C. Hearts were then perfused with fresh filtered (40-microm pore) and washed canine erythrocytes diluted in the salt solution equilibrated with 20% O2 in nitrogen (control), with 20% O2, 40% Xe, and 40% N2, (0.5 MAC), or with 20% O2 and 80% Xe (1 MAC), respectively. Hearts were perfused with 80% Xe for 15 min, and bradykinin was injected into the blood perfusate to test endothelium-dependent vasodilatory responses. Using the whole-cell patch-clamp technique, 80% Xe was tested for effects on the cardiac ion currents, the Na+, the L-type Ca2+, and the inward-rectifier K+ channel, in guinea pig myocytes suffused with a salt solution equilibrated with the same combinations of Xe, oxygen, and nitrogen as above. RESULTS: In isolated hearts, heart rate, atrioventricular conduction time, left ventricular pressure, coronary flow, oxygen extraction, oxygen consumption, cardiac efficiency, and flow responses to bradykinin were not significantly (repeated measures analysis of variance, P>0.05) altered by 40% or 80% Xe compared with controls. In isolated cardiomyocytes, the amplitudes of the Na+, the L-type Ca2+, and the inward-rectifier K+ channel over a range of voltages also were not altered by 80% Xe compared with controls. CONCLUSIONS: Unlike hydrocarbon-based gaseous anesthetics, Xe does not significantly alter any measured electrical, mechanical, or metabolic factors, or the nitric oxide-dependent flow response in isolated hearts, at least partly because Xe does not alter the major cation currents as shown here for cardiac myocytes. The authors' results indicate that Xe, at approximately 1 MAC for humans, has no physiologically important effects on the guinea pig heart.  相似文献   
10.
Objectives. To identify factors associated with academic help-seeking behavior among student pharmacists at a public university.Methods. Semi-structured focus group interviews were conducted to explore in depth perceptions of facilitators of and barriers to the help-seeking behavior and academic achievement of student pharmacists who had received a D or F grade in any year. A 4-part survey instrument was developed and administered to all student pharmacists and included sections for (1) attitudes and academic help-seeking behavior, (2) health status, (3) demographics, and (4) open comments. A structural equation modeling approach was used to assess relationships among domains of interest.Results. Three student focus groups noted that helpfulness of faculty members and school administrators were 2 prominent facilitators of help-seeking behavior and academic achievement. Diminished quality of life caused by stress and depression was the primary barrier to help-seeking and achievement. Three hundred four (68.6%) student pharmacists completed the survey instrument. Academic help-seeking behavior was influenced mostly by perceived academic competence and perceived faculty helpfulness. In contrast, ambivalence and perception of help-seeking as threatening were 2 factors that were negatively associated with academic help-seeking behavior.Conclusions. Academic help-seeking behavior was positively related to greater perceived academic competence and positive relationships among student pharmacists and faculty members.  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