全文获取类型
收费全文 | 114924篇 |
免费 | 5958篇 |
国内免费 | 355篇 |
专业分类
耳鼻咽喉 | 1758篇 |
儿科学 | 4043篇 |
妇产科学 | 3173篇 |
基础医学 | 15132篇 |
口腔科学 | 3440篇 |
临床医学 | 8296篇 |
内科学 | 27397篇 |
皮肤病学 | 3977篇 |
神经病学 | 9564篇 |
特种医学 | 2823篇 |
外国民族医学 | 30篇 |
外科学 | 15523篇 |
综合类 | 661篇 |
一般理论 | 25篇 |
预防医学 | 10005篇 |
眼科学 | 2071篇 |
药学 | 7454篇 |
中国医学 | 390篇 |
肿瘤学 | 5475篇 |
出版年
2023年 | 781篇 |
2022年 | 1455篇 |
2021年 | 3075篇 |
2020年 | 1661篇 |
2019年 | 2871篇 |
2018年 | 3551篇 |
2017年 | 2383篇 |
2016年 | 2540篇 |
2015年 | 2542篇 |
2014年 | 3795篇 |
2013年 | 5206篇 |
2012年 | 7151篇 |
2011年 | 7436篇 |
2010年 | 4311篇 |
2009年 | 3915篇 |
2008年 | 5828篇 |
2007年 | 5993篇 |
2006年 | 5904篇 |
2005年 | 5943篇 |
2004年 | 5374篇 |
2003年 | 5079篇 |
2002年 | 4812篇 |
2001年 | 3355篇 |
2000年 | 3447篇 |
1999年 | 2902篇 |
1998年 | 991篇 |
1997年 | 742篇 |
1996年 | 646篇 |
1995年 | 567篇 |
1994年 | 459篇 |
1993年 | 441篇 |
1992年 | 1347篇 |
1991年 | 1324篇 |
1990年 | 1198篇 |
1989年 | 1042篇 |
1988年 | 932篇 |
1987年 | 907篇 |
1986年 | 844篇 |
1985年 | 804篇 |
1984年 | 579篇 |
1983年 | 517篇 |
1979年 | 505篇 |
1978年 | 354篇 |
1975年 | 371篇 |
1974年 | 415篇 |
1973年 | 434篇 |
1972年 | 378篇 |
1971年 | 357篇 |
1970年 | 355篇 |
1969年 | 352篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The psychology behind doping in sport 总被引:1,自引:0,他引:1
Drugs and methods to improve physical performance among athletes have been used since the beginning of sport history, but the use of performance enhancing drugs has not always been regarded as cheating. In short, the motives for doping are improving and maintaining physical functioning, coping with the social/psychological pressures and striving for social and psychological goals, including economic benefits. Factors such as, “doping dilemma”, “win at all costs”, cost versus benefit, and the specificity of some specific doping agents, also play major roles. It seems that action on the athletes′ attitude about the achievement of physical improvement and creating effective methods to reveal the drug abuse, are two main ways in winning the struggle against doping. 相似文献
82.
83.
Marta Méndez-López Magdalena Méndez Fernando Sánchez-Patán Isabel Casado Maria-Angeles Aller Laudino López Maria-Teresa Corcuera Maria-Jose Alonso Maria-Paz Nava Jaime Arias Jorge-Luis Arias 《Journal of gastrointestinal surgery》2007,11(2):187-194
To obtain a new model of chronic portal hypertension in the rat, two classical methods to produce portal hypertension, partial portal vein ligation and the oral administration of thioacetamide (TAA), have been combined. Male Wistar rats were divided into four groups: 1 (control; n?=?10), 2 [triple partial portal vein ligation (TPVL); n?=?9], 3 (TAA; n?=?11), and 4 (TPVL plus TAA; n?=?9). After 3 months, portal pressure, types of portosystemic collateral circulation, laboratory hepatic function tests (aspartate aminotransferase, alanine aminotransferase, bilirubin, alkaline phosphatase, and gamma-glutamyl transpeptidase) and liver histology were studied. The animals belonging to group 2 (TPVL) developed extrahepatic portosystemic collateral circulation, associated with mesenteric venous vasculopathy without hepatic destructurization or portal hypertension. Animals from group 3 (TAA) developed cirrhosis and portal hypertension but not extrahepatic portosystemic collateral circulation, or mesenteric venous vasculopathy. Finally, the animals from group 4 (TPVL?+?TAA) developed cirrhosis, portal hypertension, portosystemic collateral circulation, and mesenteric venous vasculopathy. The association of TPVL and TAA can be used to obtain a model of chronic portal hypertension in the rat that includes all the alterations that patients with hepatic cirrhosis usually have. This could, therefore, prove to be a useful tool to study the pathophysiological mechanisms involved in these alterations. 相似文献
84.
A case of a pedunculated arachnoid cyst within the third ventricle is presented. The cyst was small so as not to appear as a significant expanding lesion on CT. The clinical history, however, suggested intermittent increase of the intracranial pressure. On CT there was some widening of the lateral and third ventricles, while the fourth ventricle had normal width. This finding in combination with the clinical history prompted further neuroradiologic examinations, including pneumoencephalography and ventriculography. The presence of a pedunculated mobile cystic lesion within the third ventricle was shown and its nature further elucidated by stereotactic puncture combined with contrast injection into the cyst. After emptying of the cyst, the patient has been free of symptoms during an observation time of 2 years. The diagnostic and differential diagnostic aspects are discussed and the value of traditional neuroradiologic methods emphasized. 相似文献
85.
J Vargas-Barrón A Andrade-Freire J C Ramírez E Waisser J Martínez-Sánchez 《Archivos del Instituto de Cardiología de México》1989,59(2):121-124
The purpose of this study is to determine the importance of two-dimensional echocardiography performed soon after admission to the coronary care unit to provide useful information concerning wall-motion abnormalities, and to detect and characterize left ventricular thrombi. A major goal is to identify a subgroup of patients with acute myocardial infarction who are at risk for systemic embolization; in this subgroup the benefits of anticoagulation treatment would theoretically outweigh the associated risks. We studied 7 consecutive male patients, age range from 32 to 60 years, with acute myocardial infarction. Five patients had antero-septal infarction, 1 anterolateral and another had anterior wall infarction. We performed two-dimensional echocardiography within the first week after admission. All patients had severe apical-wall-motion abnormalities (akinesis or dyskinesis) and left ventricular thrombi. All patients received anticoagulation therapy. Two-dimensional echocardiography, performed one month after the first study, showed that the thrombi had decreased in size in 6 patients and could not be visualized in 1 patient. The noninvasive nature of echocardiography allows serial evaluations of patients with known left ventricular thrombi and permits assessment of the effect of therapy. 相似文献
86.
Effect of impact exercise on bone mineral density in elderly women with low BMD: a population-based randomized controlled 30-month intervention 总被引:4,自引:3,他引:1
Raija Korpelainen Sirkka Keinänen-Kiukaanniemi Jorma Heikkinen Kalervo Väänänen Juha Korpelainen 《Osteoporosis international》2006,17(1):109-118
Evidence of the effect of exercise on bone loss comes mainly from studies in voluntary postmenopausal women, and no population-based, long-term interventions have been performed. The purpose of this population-based, randomized, controlled trial was to determine the effect of long-term impact exercise on bone mass at various skeletal sites in elderly women with low bone mineral density (BMD) at the radius and hip. Participants ( n =160) were randomly assigned to 30 months either of supervised and home-based impact exercise training or of no intervention. The primary outcome measures were femoral neck, trochanter and total hip BMD, and the secondary outcomes were bone density measures at the radius and calcaneum. Outcomes were assessed at baseline, 12 months and 30 months using blinded operators. The analyses were performed on an intention-to-treat analysis. Mean femoral neck and trochanter BMD decreased in the control group [–1.1%, 95% confidence interval (CI) –0.1% to –2.1% and –1.6%, 95% CI –0.4% to –2.7%], while no change occurred in the exercise group. Mean trochanter BMC decreased more in the control group (–7.7%, 95% CI –9.7% to –5.6% vs. –2.9%, 95% CI –5.3 to –0.9). There were six falls that resulted in fractures in the exercise group and 16 in the control group during the 30-month intervention ( P =0.019). A significant bone loss occurred in both groups at the radius and calcaneum. In multivariate analysis, weight gain was associated with increased BMD and BMC at all femur sites both in the exercise group and in the pooled groups. In conclusion, impact exercise had no effect on BMD, while there was a positive effect on BMC at the trochanter. Exercise may prevent fall-related fractures in elderly women with low bone mass.There was no conflict of interest. 相似文献
87.
Prevalence of Artemisia species pollinosis in western Poland: impact of climate change on aerobiological trends, 1995-2004. 总被引:2,自引:0,他引:2
A Stach H García-Mozo J C Prieto-Baena M Czarnecka-Operacz D Jenerowicz W Silny C Galán 《Journal of investigational allergology & clinical immunology》2007,17(1):39-47
BACKGROUND: Artemisia species pollen represents a major cause of allergy in Central Europe. Variations in the pollen season, the influence of climate variables and the prevalence of pollinosis to it were analyzed in Poznan, in western Poland between 1995 and 2004. METHODS: A Hirst volumetric spore trap was used for atmospheric sampling. Pollination date trend analysis and Spearman correlation tests were performed. Skin prick tests (SPT) and allergen specific immunoglobulin (lg)E antibody measurements were performed in 676 and 524 patients, respectively. RESULTS: The Artemisia species pollen season grew longer due to a clear advance in the starting day and only a slightly earlier end point; the peak day also came slightly earlier. Rainfall in the first fortnight of July highly influenced pollen season severity. Temperature was directly correlated with daily Artemisia species pollen levels; relative humidity was inversely correlated. Twelve percent of patients had a positive SPT reaction to Artemisia species. Their symptoms were rhinitis and conjunctivitis (15%), atopic dermatitis (15%), chronic urticaria (14.3%), bronchial asthma (2.4%), and facial and disseminated dermatitis (1.3%). Elevated specific IgE concentrations were detected in the sera of 10.1% of patients. CONCLUSIONS: Artemisia species pollen is an important cause of pollinosis in western Poland. Pollen season intensity is highly influenced by rainfall in the previous weeks. Trends towards earlier season starts and longer duration, possibly caused by climate change, may have an impact on the allergic population. 相似文献
88.
Rafael Cincu Juan F Martin L��zaro Jos�� Luis Capablo Liesa Jos�� Ram��n Ara Callizo 《Indian Journal of Orthopaedics》2007,41(4):395-397
Intramedullary epidermoid cysts of the spinal cord are rare tumors, especially those not associated with spinal dysraphism. About 50 cases have been reported in the literature. Of these, only seven cases have had magnetic resonance imaging (MRI) studies. We report two cases of spinal intramedullary epidermoid cysts with MR imaging. Both were not associated with spina bifida. In one patient, the tumor was located at D4 vertebral level; while in the other, within the conus medullaris. The clinical features, MRI characteristics and surgical treatment of intramedullary epidermoid cyst are presented with relevant review of the literature. 相似文献
89.
90.