全文获取类型
收费全文 | 84334篇 |
免费 | 8468篇 |
国内免费 | 163篇 |
专业分类
耳鼻咽喉 | 1182篇 |
儿科学 | 2537篇 |
妇产科学 | 2064篇 |
基础医学 | 11899篇 |
口腔科学 | 2022篇 |
临床医学 | 10974篇 |
内科学 | 14722篇 |
皮肤病学 | 1345篇 |
神经病学 | 6741篇 |
特种医学 | 2978篇 |
外国民族医学 | 10篇 |
外科学 | 11448篇 |
综合类 | 1715篇 |
一般理论 | 67篇 |
预防医学 | 9553篇 |
眼科学 | 1855篇 |
药学 | 6788篇 |
1篇 | |
中国医学 | 77篇 |
肿瘤学 | 4987篇 |
出版年
2021年 | 1118篇 |
2020年 | 771篇 |
2019年 | 1136篇 |
2018年 | 1446篇 |
2017年 | 1087篇 |
2016年 | 1164篇 |
2015年 | 1330篇 |
2014年 | 1728篇 |
2013年 | 2656篇 |
2012年 | 3499篇 |
2011年 | 3799篇 |
2010年 | 2079篇 |
2009年 | 2002篇 |
2008年 | 3263篇 |
2007年 | 3581篇 |
2006年 | 3446篇 |
2005年 | 3494篇 |
2004年 | 3261篇 |
2003年 | 3047篇 |
2002年 | 2973篇 |
2001年 | 2746篇 |
2000年 | 2834篇 |
1999年 | 2547篇 |
1998年 | 1155篇 |
1997年 | 979篇 |
1996年 | 963篇 |
1995年 | 866篇 |
1994年 | 865篇 |
1993年 | 781篇 |
1992年 | 2113篇 |
1991年 | 2041篇 |
1990年 | 1902篇 |
1989年 | 1887篇 |
1988年 | 1793篇 |
1987年 | 1790篇 |
1986年 | 1702篇 |
1985年 | 1688篇 |
1984年 | 1395篇 |
1983年 | 1267篇 |
1982年 | 852篇 |
1981年 | 724篇 |
1980年 | 648篇 |
1979年 | 1215篇 |
1978年 | 886篇 |
1977年 | 773篇 |
1976年 | 726篇 |
1975年 | 726篇 |
1974年 | 859篇 |
1973年 | 753篇 |
1972年 | 733篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
R Lalloo N G Myburgh M J Smith G C Solanki 《Suid-Afrikaanse tydskrif vir geneeskunde》2004,94(8):639-642
OBJECTIVES: The first democratic government elected in South Africa in 1994 inherited huge inequities in health status and health provision across all sections of the population. This study set out to assess the impact of the new government's commitment to address these inequities and implement policies to improve population health in general and address inequalities in health care in particular. DESIGN: A 1998 household survey assessed many aspects of health delivery, including their own perceived and actual access to health care among different segments of South African society. RESULTS: Race was the main predictor of perceived changes in access to health care, with black, coloured-and Indian respondents significantly more likely to feel that access had improved since 1994, compared with white respondents. Socio-economic status (SES) was the main predictor of actual access to health care, with low and middle SES classes significantly less likely to access care when ill. CONCLUSIONS: One-third of respondents perceived health care access to have improved between 1994 and 1998, and this response was partially determined along racial lines. About one-quarter reported an inability to access health care when they required it, and this response was partially determined along socio-economic lines. This set of contrasting responses suggests that at a political level perceptions are largely influenced by race, but at the operational level actual access is influenced by SES. 相似文献
103.
Gene amplification is an important mechanism of increased gene expression in a number of human solid tumors. We have recently identified and cloned sequences from a novel DNA amplification unit in malignant fibrous histiocytoma. The amplified sequences are derived from chromosome 12q13-14 and encode a gene designated SAS (sarcoma amplified sequence). In the present study, a series of soft tissue sarcomas was studied to characterize further the phenomenon of SAS amplification. Seven of 22 (32%) malignant fibrous histiocytomas and three liposarcomas contained SAS amplification. Strikingly, all of the tumors with SAS amplification occurred in central sites (i.e., in the abdominal or inguinal regions) rather than in the extremities (i.e., in the arms of legs). These observations demonstrate that SAS amplification occurs with a significant frequency in mesenchymal tumors and is particularly associated with abdominal disease. 相似文献
104.
Emma J. Birks MRCP Magdi H. Yacoub DSc FRS Ani Anyanwu FRCS Rosemary Radley Smith FRCP Nicholas R. Banner FRCP Asghar Khaghani FRCS 《The Journal of heart and lung transplantation》2004,23(12):3688-1344
BACKGROUND: Transplantation for patients with a high pulmonary vascular resistance (PVR) carries an increased risk of mortality and right heart failure following heart transplantation and continues to be a major problem. We evaluated the use of hearts from patients who underwent heart and lung transplantation for primary pulmonary hypertension (PPH) as part of a domino procedure because these hearts have hypertrophied right ventricles used to increased pulmonary pressures, but could have a compromised left ventricle or irreversible damage of the right ventricle. METHODS: We reviewed 12 patients with PVR >4 Wood units who underwent orthotopic heart transplantation between 1989 and 1998 using hearts from donors with PPH as part of a domino procedure. RESULTS: We studied 10 men and 2 women, mean age 42.9 years. Mean PVR was 5.3 (range, 4-9) Wood units. Mean ischemia time was 85.3 minutes, and mean donor age was 32 years. Actuarial survival was 75% at 1 year and 75% at 5 years. In the early post-operative period, 3 patients had temporary arrhythmias, 2 required permanent pacemaker implantation, 1 had atrial fibrillation, and 1 had ventricular tachycardia that required defibrillator implantation. At a mean follow-up of 7.8 years, 2 patients had developed asymptomatic transplant coronary disease (both at 8.5 years after transplantation), 1 moderate and 1 very mild; the rest had none. Mean left ventricular ejection fraction at latest follow-up was 70.1% (range, 63%-78%). Right ventricular function assessed clinically and by echocardiography was adequate in the short and long term. CONCLUSIONS: Our results suggest that heart and lung recipients with PPH can provide useful donor hearts to patients with increased PVR and that these hearts function well in the intermediate and long term. 相似文献
105.
106.
107.
The definition, classification, proposed etiologies, diagnosis, and treatment of the premenstrual syndrome (PMS) are discussed, and guidelines for the clinical management of PMS are presented. PMS encompasses a cluster of physical and psychosocial symptoms that recur during each menstrual cycle. Proposed etiologies for the syndrome include a hormonal imbalance between estrogen and progesterone, pyridoxine hydrochloride deficiency, hypoglycemia, excess prostaglandin production, and increased aldosterone concentrations in the luteal phase of the menstrual cycle. Diagnosis of PMS is usually based on a patient's history of recurrent symptoms accompanied by a seven-day, symptom-free period in the first half of the menstrual cycle. Management of PMS is complicated by the difficulty in diagnosing the syndrome and its unclear etiology. If possible, conservative nonpharmacologic treatment should be tried initially; suggested measures include modifications in diet, exercise, substance use, stress factors, rest patterns, and social support. Pharmacologic treatment should be considered when conservative therapies are ineffective or when PMS symptoms are more severe. Although most therapies are empirical, treatment with progesterone, pyridoxine, bromocriptine, or diuretics might prove beneficial. Once the decision is made to initiate drug therapy, the treatment regimen should be individualized and based on the patient's PMS symptom complex. The clinical management of PMS is complicated by the lack of well-designed clinical investigations of proposed treatments. Future research should be directed toward evaluating the efficacy of proposed therapeutic regimens. 相似文献
108.
H Dexter Barber John Lignelli Brian M Smith Barry K Bartee 《Journal of oral and maxillofacial surgery》2007,65(4):748-752
The most common types of barrier membranes used for bone or tissue regeneration are made of expanded-polytetrafluoroethylene (e-PTFE) or resorbable materials, such as collagen. Both the e-PTFE and resorbable membranes require primary soft tissue coverage. This article explores the use of a dense-polytetrafluoroethylene (d-PTFE) membrane, which does not require primary soft tissue coverage. The advantages of d-PTFE in contrast to the other more commonly used types of barrier membranes and the clinical significance of these advantages for implant surgical and restorative treatment are discussed. 相似文献
109.
R Smith 《British medical journal (Clinical research ed.)》1987,294(6579):1047-1048
110.
N S Fuleihan M A Natout R C Webster N A Hariri M A Samara R C Smith 《Otolaryngology--head and neck surgery》1987,97(1):18-23
Amputations of the nose and of the auricle present difficult management problems. Application of simple reattachment techniques, followed by aggressive medical therapy which consists of cooling, anticoagulation, antibiotic coverage, and multiple stab incisions in the amputated tissues, have resulted in the successful replantation of major portions of an amputated nose and an amputated auricle with satisfactory cosmetic results. 相似文献