全文获取类型
收费全文 | 1512224篇 |
免费 | 105703篇 |
国内免费 | 3376篇 |
专业分类
耳鼻咽喉 | 20870篇 |
儿科学 | 49205篇 |
妇产科学 | 41388篇 |
基础医学 | 222784篇 |
口腔科学 | 42148篇 |
临床医学 | 131051篇 |
内科学 | 297516篇 |
皮肤病学 | 33101篇 |
神经病学 | 114318篇 |
特种医学 | 58614篇 |
外国民族医学 | 405篇 |
外科学 | 232384篇 |
综合类 | 32334篇 |
现状与发展 | 2篇 |
一般理论 | 393篇 |
预防医学 | 109894篇 |
眼科学 | 34591篇 |
药学 | 111362篇 |
3篇 | |
中国医学 | 3934篇 |
肿瘤学 | 85006篇 |
出版年
2018年 | 15710篇 |
2017年 | 12293篇 |
2016年 | 13511篇 |
2015年 | 15225篇 |
2014年 | 21145篇 |
2013年 | 32370篇 |
2012年 | 43140篇 |
2011年 | 45682篇 |
2010年 | 27502篇 |
2009年 | 25990篇 |
2008年 | 43263篇 |
2007年 | 46250篇 |
2006年 | 46689篇 |
2005年 | 45088篇 |
2004年 | 43515篇 |
2003年 | 41804篇 |
2002年 | 40992篇 |
2001年 | 72134篇 |
2000年 | 73824篇 |
1999年 | 62219篇 |
1998年 | 16834篇 |
1997年 | 14931篇 |
1996年 | 15034篇 |
1995年 | 14204篇 |
1994年 | 13303篇 |
1993年 | 12375篇 |
1992年 | 48045篇 |
1991年 | 46863篇 |
1990年 | 45841篇 |
1989年 | 44584篇 |
1988年 | 40983篇 |
1987年 | 40165篇 |
1986年 | 38432篇 |
1985年 | 36298篇 |
1984年 | 26939篇 |
1983年 | 22957篇 |
1982年 | 13320篇 |
1979年 | 24821篇 |
1978年 | 17400篇 |
1977年 | 14731篇 |
1976年 | 14077篇 |
1975年 | 15479篇 |
1974年 | 18345篇 |
1973年 | 17504篇 |
1972年 | 16518篇 |
1971年 | 15328篇 |
1970年 | 14769篇 |
1969年 | 13748篇 |
1968年 | 12918篇 |
1967年 | 11812篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Human immunodeficiency virus infection in urban Rwanda. Demographic and behavioral correlates in a representative sample of childbearing women 总被引:9,自引:0,他引:9
S Allen C Lindan A Serufilira P Van de Perre A C Rundle F Nsengumuremyi M Carael J Schwalbe S Hulley 《JAMA》1991,266(12):1657-1663
OBJECTIVE.--To determine behavioral and demographic risk factors for human immunodeficiency virus (HIV) infection in central Africa. DESIGN.--Cross-sectional survey. SETTING.--Kigali, Rwanda. PARTICIPANTS.--A representative sample of 1458 childbearing women aged 19 to 37 years who were recruited from outpatient prenatal and pediatric clinics at the only community hospital in the city. MAIN OUTCOME MEASURE.--Antibodies to HIV assessed by enzyme immunoassay and confirmed by Western blot or indirect immunofluorescence. RESULTS.--The HIV seroprevalence was 32% overall. Infection rates were higher in women who were single, in those in steady relationships that began after 1981, and in the 33% of women reporting more than one lifetime sexual partner. Women in legal marriages or monogamous partnerships had lower rates of infection, but even low-risk women had prevalences on the order of 20%. History of venereal disease in the past 5 years, although the strongest risk factor in a multiple logistic analysis (odds ratio, 2.7; 95% confidence interval, 2.0 to 3.7), was reported by only 30% of those infected. Having a male sexual partner who drank alcohol or who had higher income were significant risk factors for HIV infection in the multivariate analysis, but use of oral contraceptives and having an uncircumcised partner were not. CONCLUSIONS.--The epidemic of the acquired immunodeficiency syndrome in Rwanda has spread beyond high-risk groups to the general population of women without known risk factors. For most of these women, a steady male partner is the source of their HIV risk and therefore a vital target for intervention efforts. 相似文献
992.
993.
994.
Harold C. Lyon Jr. James C. Healy James R. Bell Joseph F. O'Donnell Edward K. Shultz Robert S. Wigton Frank Hirai J. Robert Beck 《Journal of medical systems》1991,15(2):117-132
Richard E. Clark in his widely published comprehensive studies and meta-analyses of the literature on computer assisted instruction (CAI) has decried the lack of carefully controlled research, challenging almost every study which shows the computer-based intervention to result in significant post-test proficiency gains over a non-computer-based intervention. We report on a randomized study in a medical school setting where the usual confounders found by Clark to plague most research, were carefully controlled. PlanAlyzer is a microcomputer-based, self-paced, case-based, event-driven system for medical education which was developed and used in carefully controlled trials in a second year medical school curriculum to test the hypothesis that students with access to the interactive programs could integrate their didactic knowledge more effectively and/or efficiently than with access only to traditional textual “nonintelligent” materials. PlanAlyzer presents cases, elicits and critiques a student's approach to the diagnosis of two common medical disorders: anemias and chest pain. PlanAlyzer uses text, hypertext, images and critiquing theory. Students were randomized, one half becoming the experimental group who received the interactive PlanAlyzer cases in anemia, the other half becoming the controls who received the exact same content material in a text format. Later in each year there was a crossover, the controls becoming the experimentals for a similar intervention with the cardiology PlanAlyzer cases. Preliminary results at the end of the first two full trials shows that the programs have achieved most of the proposed instructional objectives, plus some significant efficiency and economy gains. 96 faculty hours of classroom time were saved by using PlanAlyzer in their place, while maintaining high student achievement. In terms of student proficiency and efficiency, the 328 students in the trials over two years were able to accomplish the project's instructional objectives, and the experimentals accomplished this in 43% less time than the controls, achieving the same level of mastery. However, in spite of these significant efficiency findings, there have been no significant proficiency differences (as measured by current factual and higher order multiple choice post-tests) between the experimental and control groups. Very careful controls were used to avoid what Clark has found to be the most common confounders of CAI research. Accordingly, this research proved Clark's rival hypothesis, that the computer, in itself, does not appear to contribute to proficiency gains, at least as measured by our limited post-testing. Clark's position is that the computer is primarily a vehicle—as is either a pill or a hypodermic needle for delivering a drug. The hypodermic needle can deliver the drug more efficiently than can the pill, (as can the computer deliver the subject matter content more efficiently, as our research indicates), but the same content is delivered. At the same time, we proved our own hypothesis, as far as efficiency gains resulting from the computer are concerned. However, going beyond Clark's research, we may be teaching processes both more effectively and efficiently with the computer (experience in problem-solving or clinical reasoning and pattern recognition) which our current post-tests do not adequately measure. Our on-going research suggests additional inquiry in several areas: better evaluation instruments to measure the clinical reasoning skills PlanAlyzer was designed to teach; the addition of more advanced cases to determine if this might transform efficiency gains of the computer group into proficiency gains; the addition of enhanced graphic decision support tools and other pedagogical enhancements including cognitive feedback to strengthen PlanAlyzer's power to teach complex concepts of medical decision-making. 相似文献
995.
J. E. Hammond R. G. Berger T. S. Carey R. Rutledge T. J. Cleveland J. P. Kichak C. F. Ayscue 《Journal of medical systems》1991,15(3):257-267
Many hospitals today have implemented widely disparate information systems on mainframe and mini-computer hardware. The advent of network technology in hospitals has made it possible to access information in these systems. Unfortunately, the user interfaces to applications on these systems are unique and difficult to learn, which makes them unsuitable for use by clinical services. In this paper we describe the development of a Physician's Workstation which integrates information from multiple existing information systems and discuss how the workstation makes it possible to move from the departmental systems of the present to the computer-based medical record system of the future. 相似文献
996.
From October to December 1984, examination has been carried out on Salmonella-typhi cultures from blood, bone marrow, faeces and urine of 43 patients suffering from suspected typhoid fever treated in the Department of Child Health, Medical School/Hasan Sadikin General Hospital, Bandung. It was apparent that among these 43 patients, 51.2% were males and 48.8% females. The greater number of them were more than 5 years old (64.4%). The results of Salmonella-typhi cultures were obtained from 65% of the patients, consisting of 65% positive cultures from bone-marrow and 40% positive cultures from blood that showed a statistically significant difference (p less than 0.05). Likewise, the time for matter-sampling for the examinations was based on the culture results, both on blood-culture and that of bone-marrow, statistically a significant was found (p less than 0.05), whereas the results of cultures based on previous vaccination history and the administration of chloramphenicol prior to treatment did not differ significantly. It was obviously clear that the results of bone-marrow culture were more successful compared to those from blood culture, so that it should necessarily be emphasized, as to these examinations on culture from each patient with suspected typhoid fever, especially those patients hospitalized during the third week of their illness. 相似文献
997.
998.
999.
Gram negative endotoxins play a contributory role in the syndrome which results from over consumption of carbohydrates by horses and ponies. Since the antibiotic polymyxin B exerts a direct anti-endotoxin effect by chemically modifying the active lipid A moiety of endotoxin, it might be expected to protect horses after carbohydrate overload and provide a new therapeutic and experimental tool for this condition. The present study was undertaken to evaluate the effect of polymyxin B on hemostatic, hemodynamic, acid-base, and clinical aspects of the syndrome resulting from carbohydrate overload. Experimentally-induced carbohydrate overload resulted in lactic acidosis, hypercoagulability, hypovolemic shock and lameness. Although there was a slight delay in the onset of clinical signs resulting from experimental carbohydrate overload in treated animals, polymyxin B administered iv at 2.5 mg/kg every 6 hr failed to significantly ameliorate the coagulopathy, acidosis, lameness and shock induced by alimentary carbohydrate overload. 相似文献
1000.
The effect of zinc supplementation on the metabolism of tryptophan conversion to niacin was studied in 14 alcoholic patients with pellagra and in 7 male control subjects aged 21-45 y. The pellagrins received chemically defined diets based on crystalline amino acids through an enteral tube for 7 d. Patients were divided into two groups (A and B), both receiving a diet from which tryptophan, Zn, and niacin were excluded. Patients in group B, however, received 220 mg Zn sulfate orally. Upon admission the pellagra patients had low plasma Zn levels and low urinary excretion values of N'methylnicotinamide (N'MN) and N'methyl-2-pyridone-5-carboxamide (2-PYR) in relation to the control subjects (p less than 0.01). During the experimental period there was an increase in plasma Zn levels (p less than 0.005) and in urinary N'MN (p less than 0.05) and 2-PYR (p less than 0.05) excretion in the patients receiving Zn supplementation (group B). These results suggest that Zn interacts with niacin metabolism in alcoholic patients with pellagra through a probable mediation by vitamin B-6. 相似文献