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   17719篇
  免费   2075篇
  国内免费   229篇
耳鼻咽喉   70篇
儿科学   626篇
妇产科学   891篇
基础医学   989篇
口腔科学   128篇
临床医学   1327篇
内科学   5241篇
皮肤病学   198篇
神经病学   875篇
特种医学   141篇
外国民族医学   1篇
外科学   2774篇
综合类   1083篇
一般理论   1篇
预防医学   2935篇
眼科学   63篇
药学   818篇
中国医学   90篇
肿瘤学   1772篇
  2024年   28篇
  2023年   477篇
  2022年   484篇
  2021年   1206篇
  2020年   916篇
  2019年   1072篇
  2018年   968篇
  2017年   785篇
  2016年   777篇
  2015年   756篇
  2014年   1156篇
  2013年   1422篇
  2012年   750篇
  2011年   891篇
  2010年   666篇
  2009年   758篇
  2008年   766篇
  2007年   750篇
  2006年   718篇
  2005年   552篇
  2004年   514篇
  2003年   437篇
  2002年   346篇
  2001年   310篇
  2000年   230篇
  1999年   200篇
  1998年   198篇
  1997年   184篇
  1996年   165篇
  1995年   148篇
  1994年   132篇
  1993年   124篇
  1992年   111篇
  1991年   91篇
  1990年   80篇
  1989年   67篇
  1988年   82篇
  1987年   63篇
  1986年   79篇
  1985年   86篇
  1984年   102篇
  1983年   63篇
  1982年   72篇
  1981年   48篇
  1980年   35篇
  1979年   41篇
  1978年   28篇
  1976年   24篇
  1975年   21篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
61.
Recent studies of mortality from motor neurone disease (MND) in Sweden have demonstrated rising levels of mortality from the disease, especially amongst older age groups. Case-control investigations have suggested that certain environmental factors are significantly related to variations in mortality from the disease, and are associated with a probable individual susceptibility to MND. This study applies an innovative epidemiological technique to longitudinal and cohort analysis of Swedish mortality from MND during the period 1961 to 1990. Survival modelling shows that a subpopulation susceptible to MND exists in Sweden, as has been demonstrated in other countries. The increased life expectancy of the Swedish population since 1961 has resulted in more of that susceptible population living to the ages at which MND is expressed, explaining the majority of the increase in mortality from the disease. However, environmental factors may play a role in accelerating the course of MND and may affect the timing of death within the susceptible sub-population.  相似文献   
62.
Death certificates from 23,890 male and female non-Hodgkin's lymphoma (NHL) cases and 119,450 noncancer controls from 24 states for the period 1984-1989 were used to generate hypotheses regarding occupational associations. Cases were frequency matched by age, race, and gender with five controls per case. Odds ratios were calculated for 231 industries and 509 occupations. Significant associations were observed for a variety of white-collar professionals (i.e., real estate agents, secretaries, bookkeepers, teachers, postal employees, business agents, engineers, chemists, and medical professionals) and blue-collar occupations (i.e., firefighters, farm managers, aircraft mechanics, electronic repairers, mining machine operators, and crane and tower operators). © 1995 Wiley-Liss, Inc.  相似文献   
63.
Familial amyloidotic polyneuropathy (FAP) with a mutation in position 30 of transthyretin (TTR) (previously called prealbumin) is an autosomal dominant inherited disorder characterized by varying degrees of peripheral neuropathy, nephropathy, gastrointestinal problems, and vitreous amyloid. We have earlier diagnosed homozygosity for the TTR-Met30-gene using Southern analysis in four Swedish individuals. We have found it possible to detect homozygosity for the Met-30 mutation by amplifying discrete regions of the TTR-gene using polymerase chain reaction (PCR), and the amplification products restricted with NsiI analysed by gel electrophoresis. Clinical data on seven homozygous individuals, including three new cases, are presented.  相似文献   
64.
Consecutive survivors of a myocardial infarction from the Southern Hospital, below 70 years of age, were randomized into a Control group (n=276) and a Treatment group (n=279). The latter was openly prescribed the combination of clofibrate and nicotinic acid for serum lipid lowering. Each patient should remain in the study for 5 years and be seen regularly every 4 months at a special IHD outpatient clinic within the hospital. The concentration of serum cholesterol and triglyceride was lowered by 13% and 19%, respectively, in the Treatment group compared to the Control group. Total mortality was 82 cases in the Control group and 61 in the Treatment group, a 26% reduction (p<0.05). For patients above 60 years of age in the Treatment group the reduction in mortality was 28% (p<0.05). IHD mortality was reduced by 36% (p<0.01)in the Treatment group compared to the Control group. The beneficial effect of the serum lipid lowering treatment was related to the serum triglyceride concentration in two ways. First, it only occurred in patients with a triglyceride level >1.5 mmol/l (n=216). Secondly, it was most pronounced in the 44% of the treated patients who had a lowering of the serum triglyceride concentration by 30% or more, and in this subgroup the reduction of IHD mortality was 60% (p<0.01). For serum cholesterol there were no such relations. The difference between serum triglycerides and cholesterol concerning these relations to the treatment outcome may be due to the fact that hypertriglyceridaemia was the most common hyperlipidaemia among our patients, occurring in 50%, while hypercholesterolaemia only occurred in 13 %. Caution should be exercised in the interpretation of the results as the trial was not blind. However, the fact that the decrease in IHD deaths was directly related to the degree of serum triglyceride lowering indicates that it was the drug effect on serum lipids that was reponsible for the beneficial effect of the treatment.  相似文献   
65.
We have studied the mortality between 1950 and 1980 of a cohort of 1,143 workers in an electrochemical plant producing cobalt and sodium. The mortality of the whole cohort is significantly lower than in the French population for all causes of death (SMR = 0.77), and especially for deaths from circulatory system diseases (SMR = 0.59). However, among cobalt production workers, there is a relative over-mortality, especially from lung cancers (SMR = 4.66, 4 cases). The relationship between cobalt production and lung cancer mortality was supported by a case-control study nested in the cohort study. The authenticity of the occupational origin of this risk could not be established due to the low number of cases and because the role of tobacco consumption could not be taken into account. Other studies should be carried out in plants producing or using cobalt.  相似文献   
66.
经调查河南省七县1988~04~1989~03孕产妇死亡率为136.1/10万,高于全国平均水平(94.7/10万)。从七县中选择了死亡率偏高的三个县(147.9/10万)为样本.进行厂降低农村孕产妇死亡率保健措施的研究。自1990年4月1日~1992年3月31日。在三县采取了以下保健措施:①加强基层妇幼卫生建设,特别是中心乡卫生院的建设,②整顿和完善三级保健网;③建全孕产妇系统管理制度,高危妊娠筛查,转化和转诊制度,④配备必要设备,建立联合小产院,实行定点接生。两年内孕产妇死亡率,由1989年的147.9/10万下降到67.7/10万,下降幅度为54.44%,最高达72.1%。此工作为实现2000年孕产妇死亡率下降一半的规划目标提供了依据。  相似文献   
67.
目的 床旁临时起搏器作为急性心肌梗死(AMI)的常备急救设备的价值及其在基层医院推广应用的可行性研究。方法 回顾性研究分析2001-2003年间不能床旁植入临时起搏器与2004-2005年能床旁植入临床起搏器抢救AMI的住院病死率、心衰、心源性休克、2mo后再次住院发生率。临时起搏器植入术安全性的指标比较。结果 不能床旁植入临时起搏器组的住院病死率为14.58%,心衰发生率为27.08%,心源性休克发生率为12.5%,2mo后再次住院发生率为16.67%。床旁植入临时起搏器组的住院病死率为3.57%,心衰发生率为7.14%,心源性休克发生率为3.57%,2mo后再次住院发生率为3.57%,两组相比p〈0.01有显著性差异。而起搏器植入的安全性指标:起搏器植入成功率为100%,脱位率为10.7%,并发症发生率为14.3%,住院病死率3.57%。结论 床旁临时起搏器抢救AMI住院病死率低,心衰发生率、心源性休克发生率及2mo后再次住院发生率低,应作为AMI抢救的常备急救设备,另外床旁临时起搏器植入是安全的、有效的,成功率高,操作不难,在基层医院(二甲医院)可推广应用。  相似文献   
68.
OBJECTIVE: The 5-year project in the province of Sofala was designed to improve access, quality and utilization of emergency obstetric care (EmOC) by strengthening rural hospitals and health centers and ultimately the health system's capacity to respond to emergencies more quickly and effectively. METHODS: Implementation consisted of attention to infrastructure, human resource development, transportation and communication systems, and management. Specific management aspects that were targeted for improvement included: supportive supervision, logistics for supplies, equipment and drugs, record keeping, monitoring and evaluation, and quality improvement techniques such as maternal death audits. RESULTS: Access to EmOC improved with an increase in the number of fully functional EmOC facilities from 4 to 18. The number of women with obstetric complications who were admitted for treatment in participating facilities tripled, and the proportion of those women dying declined by half. CONCLUSIONS: Close collaboration and partnership with the provincial health directorate make the sustainability of many results likely while the replication of much of the Sofala model to other provinces is promising for the national strategy to reduce maternal mortality.  相似文献   
69.
ABSTRACT: Background: The percentage of United States’ births delivered by cesarean section has increased rapidly in recent years, even for women considered to be at low risk for a cesarean section. The purpose of this paper is to examine infant and neonatal mortality risks associated with primary cesarean section compared with vaginal delivery for singleton full‐term (37–41 weeks’ gestation) women with no indicated medical risks or complications. Methods: National linked birth and infant death data for the 1998–2001 birth cohorts (5,762,037 live births and 11,897 infant deaths) were analyzed to assess the risk of infant and neonatal mortality for women with no indicated risk by method of delivery and cause of death. Multivariable logistic regression was used to model neonatal survival probabilities as a function of delivery method, and sociodemographic and medical risk factors. Results: Neonatal mortality rates were higher among infants delivered by cesarean section (1.77 per 1,000 live births) than for those delivered vaginally (0.62). The magnitude of this difference was reduced only moderately on statistical adjustment for demographic and medical factors, and when deaths due to congenital malformations and events with Apgar scores less than 4 were excluded. The cesarean/vaginal mortality differential was widespread, and not confined to a few causes of death. Conclusions: Understanding the causes of these differentials is important, given the rapid growth in the number of primary cesareans without a reported medical indication. (BIRTH 33:3 September 2006)  相似文献   
70.
BACKGROUND: Advanced glycation end products (AGEs) have biological properties that may contribute to the premature cardiovascular mortality of haemodialysis patients. This study examines the hypothesis that low molecular weight forms of fluorescent AGEs (LMW fluorescence) predict mortality in haemodialysis patients. METHODS: The LMW fluorescence was measured in 85 patients treated with chronic haemodialysis and prospectively followed for 4 years. The primary outcome of all-cause mortality was assessed using Cox proportional hazards regression model. RESULTS: At the end of the follow-up period 37 (44%) patients died. The median LMW fluorescence level was 24.2 arbitrary units (range: 10.6-148.1 AU) and the receiver operator characteristic (ROC) curve cut-off for mortality was 37.0 AU. The LMW fluorescence predicted death both as a binary variable at the ROC cut-off, and as a continuous log-transformed variable when adjusted for age, albumin and C-reactive protein (CRP). Adjusted for age, albumin and CRP, the hazard ratio for mortality was 3.05 (1.41-6.60, P = 0.005) for LMW fluorescence as a binary variable and 2.71 per log unit (1.37-5.38, P = 0.004) as a continuous log-transformed variable. CONCLUSION: The low molecular weight forms of AGEs predict mortality in patients receiving chronic haemodialysis, and may be important in the mechanisms leading to atherosclerosis and inflammation in such patients.  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