全文获取类型
收费全文 | 377741篇 |
免费 | 288002篇 |
国内免费 | 42522篇 |
专业分类
耳鼻咽喉 | 3543篇 |
儿科学 | 6444篇 |
妇产科学 | 2857篇 |
基础医学 | 95470篇 |
口腔科学 | 5047篇 |
临床医学 | 74089篇 |
内科学 | 103862篇 |
皮肤病学 | 6156篇 |
神经病学 | 24567篇 |
特种医学 | 13380篇 |
外国民族医学 | 2篇 |
外科学 | 51881篇 |
综合类 | 90233篇 |
现状与发展 | 38篇 |
一般理论 | 2篇 |
预防医学 | 58767篇 |
眼科学 | 19935篇 |
药学 | 74231篇 |
192篇 | |
中国医学 | 57429篇 |
肿瘤学 | 20140篇 |
出版年
2022年 | 7356篇 |
2021年 | 8574篇 |
2020年 | 10568篇 |
2019年 | 14930篇 |
2018年 | 15429篇 |
2017年 | 17194篇 |
2016年 | 14978篇 |
2015年 | 17337篇 |
2014年 | 19100篇 |
2013年 | 20539篇 |
2012年 | 24369篇 |
2011年 | 26775篇 |
2010年 | 28852篇 |
2009年 | 35672篇 |
2008年 | 23244篇 |
2007年 | 19339篇 |
2006年 | 17784篇 |
2005年 | 15489篇 |
2004年 | 15264篇 |
2003年 | 13378篇 |
2002年 | 12637篇 |
2001年 | 14436篇 |
2000年 | 9147篇 |
1999年 | 12877篇 |
1998年 | 13794篇 |
1997年 | 13707篇 |
1996年 | 14787篇 |
1995年 | 14972篇 |
1994年 | 14737篇 |
1993年 | 13498篇 |
1992年 | 12709篇 |
1991年 | 12105篇 |
1990年 | 11083篇 |
1989年 | 10947篇 |
1988年 | 10501篇 |
1987年 | 9861篇 |
1986年 | 9375篇 |
1985年 | 8445篇 |
1984年 | 6531篇 |
1983年 | 6548篇 |
1982年 | 7606篇 |
1981年 | 7144篇 |
1980年 | 6810篇 |
1979年 | 6642篇 |
1978年 | 5818篇 |
1977年 | 6122篇 |
1976年 | 5745篇 |
1975年 | 5484篇 |
1974年 | 5034篇 |
1972年 | 4754篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The Institute of Medicine distinguishes between programs based on who is targeted: the entire population (universal), those
at risk (selective), or persons exhibiting the early stages of use or related problem behavior (indicated). Evaluations suggest
that although universal programs can be effective in reducing and preventing substance use, selective and indicated programs
are both more effective and have greater cost-benefit ratios. This paper tests these assumptions by comparing the impact of
these program types in reducing and preventing substance use at the individual level (i.e., those exposed to intervention
services) and in the population (i.e., those exposed and not exposed to intervention services). A meta-analysis was performed
on 43 studies of 25 programs to examine program comparability across IOM categories. When examining unadjusted effect sizes
at the individual level, universal programs were modestly more successful in reducing tobacco use, but selective and indicated
programs were modestly more successful in reducing alcohol and marijuana use. When adjusted to the population level, the average
effect sizes for selective and indicated programs were reduced by approximately half. At the population level, universal programs
were more successful in reducing tobacco and marijuana use and selective and indicated programs were more successful in reducing
alcohol use. Editors’ Strategic Implications: The authors’ focus on the public health value of a prevention strategy is compelling and provides a model for analyses of
other strategies and content areas. 相似文献
92.
Fu-Wei Wang Yu-Wen Chiu Ming-Shium Tu Ming-Yueh Chou Chao-Ling Wang Hung-Yi Chuang 《International archives of occupational and environmental health》2009,82(7):819-825
Purpose There has been increasing interest in the occupational health of workers in small enterprises, especially in developing countries.
This study examines the association between psychosocial job characteristics and fatigue, and attempts to identify risk factors
for fatigue among workers of small enterprises in southern Taiwan.
Methods A structured questionnaire was administered to workers receiving regular health examinations between August 2005 and January
2006. The questionnaire collected demographic information and data on working conditions, personal health status and life
styles. It also collected information on psychosocial job characteristics, fatigue and psychological distress using three
instruments.
Results A total of 647 workers with mean age of 43.7 were completed. Probable fatigue was found in 34.6% of the sample. Fatigue was
found by multiple logistic regressions to be associated with the lack of exercise, working in shifts, depression score and
lack of social support at workplace.
Conclusions This study found associations between life style, psychosocial job characteristics and fatigue. Because the high prevalence
of probable fatigue was found in such small enterprises, the authors suggest that a short interview with some quick questionnaires
in health checkup for these small enterprise workers are helpful to early detect psychosocial and fatigue problems. 相似文献
93.
94.
Transplantation of microencapsulated bovine chromaffin cells reduces lesion-induced rotational asymmetry in rats 总被引:7,自引:0,他引:7
Surrounding bovine chromaffin cells by a semipermeable membrane may protect the transplanted cells from a host immune response and shield them from the inflammatory process resulting from the surgical trauma. Encapsulation of the chromaffin cells was achieved by inter-facial adsorption of a polycation on a polyanionic colloid matrix in which the chromaffin cells were entrapped. Basal and potassium-evoked release of catecholamines from encapsulated bovine chromaffin cells was analyzed over a 4-week period in vitro. Norepinephrine and dopamine release remained constant over time whereas epinephrine release significantly decreased. The chromaffin cells also retained the capacity for depolarization-elicited catecholamine release 4 weeks following the encapsulation procedure. Morphological analysis revealed the presence of intact chromaffin cells with well-preserved secretory granules. Striatial implantation of chromaffin cell-loaded capsules significantly reduced apomorphine-induced rotation compared to empty polymer capsules in animals lesioned with 6-hydroxydopamne frr at least 4 weeks. Intact chromaffin cells expressing tyrosine hydroxylase and dopamine-β-hydroxylase were observed in all capsules implanted in the striatum for 4 weeks. The assessment of the clinical potential of transplanting encapsulated adrenal chromaffin cells of either allo- or xenogeneic origin for Parkinson's disease will require long-term behavioral studies. The present study suggests, however, that the polymer encapsulation procedure may offer an alternative to adrenal autografts as a source of dopaminergic tissue. 相似文献
95.
Dissection of the extracranial vertebral artery: report of four cases and review of the literature. 下载免费PDF全文
P Hinse A Thie L Lachenmayer 《Journal of neurology, neurosurgery, and psychiatry》1991,54(10):863-869
Four cases of cervical vertebral artery (VA) dissection are reported. In three patients VA dissection was associated with neck trauma. All patients were young or middle-aged (range 27 to 49 years). In two there was a history of migraine. Pain preceded neurological symptoms from hours to six weeks. Three patients had neurological deficits including elements of the lateral medullary syndrome, and one experienced recurrent transient ischaemic attacks in the vertebrobasilar territory. Angiographic findings included irregular stenosis, occlusion and pseudoaneurysm; in two patients VA abnormalities were bilateral. All patients were treated with anticoagulants and improved. In a review of 28 cases with traumatic dissection and 29 cases with spontaneous dissection of the VA reported in the literature, distinct clinical and angiographic features emerge. Aetiology remains obscure in most cases of spontaneous dissection and management is still controversial. 相似文献
96.
97.
G.E. ORLANDINI S. ZECCHI ORLANDINI A.F. HOLSTEIN R. EVANGELISTI and R. PONCHIETTI 《Andrologia》1987,19(3):315-321
The human prostatic urethra has been investigated by means of scanning electron microscopy. On the posterior wall of the urethra, the seminal colliculus with the orifices of the ejaculatory ducts is clearly detectable. The upper portion of the prostatic urethra shows a typical transitional epithelium with large superficial cells of a ruffled appearance. In the lower portion of the organ (underneath the openings of the ejaculatory ducts), the apical pattern of the cells varies considerably. Four main aspects are recognizable: apices provided with microvilli, dome-shaped apices with an almost smooth surface, large apices with labyrinthic microplicae and ciliated apices. Also, apices showing intermediate characteristics can be noted. The functional significance of the morphological patterns as well as the possibility of a transition among the various types of surface structures are discussed. 相似文献
98.
J. Duteil FA Rambert AM Pointeau P. Mangiameli and E. Assous 《Fundamental & clinical pharmacology》1991,5(8):695-708
The potential antidepressant effect of flerobuterol (dl-(fluoro-2 phenyl)-1 t-butylamino-2 ethanol), a new drug related to beta-adrenoceptor agonists, was evaluated and compared with imipramine and salbutamol using classical psychopharmacological tests in mice. Like imipramine and salbutamol, flerobuterol (0.5-32 mg kg-1, ip) fully prevented apomorphine (16 mg kg-1, sc)- and partly reversed reserpine- and oxotremorine-induced hypothermia. At higher doses (16-32 mg kg-1), flerobuterol enhanced the toxic effects of yohimbine. Unlike imipramine, flerobuterol and salbutamol did not reduce immobility duration in the behavioural despair test. Salbutamol and flerobuterol decreased locomotor activity. Flerobuterol did not induce mydriasis, did not prevent oxotremorine-induced tremors or salivary and lacrimal gland secretion and did not reduce reserpine-induced palpebral ptosis. Propranolol (8 mg kg-1, ip) but not alpha-methyl-paratyrosine (75 mg kg-1, ip) prevented the flerobuterol-induced antagonism of apomorphine-induced hypothermia. Our results suggest that flerobuterol demonstrates potential antidepressant activity, which could be related to beta-adrenoceptor activation in mice. 相似文献
99.
100.
A cross-sectional survey of patients' beliefs about stress and their help-seeking behaviour 下载免费PDF全文
BACKGROUND: Stress has become an increasingly common presentation in general practice. This may relate to an increase in stress in people's lives or a change in the meaning of stress and its conceptualisation as a legitimate problem for the GP. AIM: To explore patients' beliefs about stress, their association with help-seeking behaviour, and to examine differences by ethnic group. DESIGN OF STUDY: Cross-sectional survey of general practice patients attending to see their GP. SETTING: An inner-city London practice. METHOD: Consecutive general practice patients completed a questionnaire, which involved rating a series of symptoms for the extent to which they were associated with stress and describing their help-seeking behaviour. In total, 548 patients completed the questionnaire. Most patients described themselves as black Caribbean (n = 163), black African (n = 48), or white British (n = 187). RESULTS: The symptoms most frequently associated with stress were sleeping problems, feeling depressed, feeling panicky, having high blood pressure and feeling anxious; feeling ashamed, experiencing indigestion, having diarrhoea, feeling hot or cold, and suffering from constipation were least commonly associated to stress. This model of stress did not vary by ethnic group. Ethnic group differences were found for the association between the model of stress and help-seeking behaviour. Although white British patients consistently reported that the more a symptom was seen as indicative of stress, the more likely they would be to visit the doctor for that symptom, this association was not found for either black Caribbean or black African patients. CONCLUSIONS: The belief that stress-related symptoms are a legitimate problem for the GP is not universal and varies according to ethnic group. Stress is used by different patients in different ways and offers a variable pathway to the doctor. 相似文献