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   1419篇
  免费   72篇
  国内免费   56篇
耳鼻咽喉   1篇
儿科学   73篇
妇产科学   8篇
基础医学   156篇
口腔科学   21篇
临床医学   163篇
内科学   377篇
皮肤病学   52篇
神经病学   27篇
特种医学   311篇
外科学   97篇
综合类   23篇
预防医学   62篇
眼科学   5篇
药学   60篇
中国医学   2篇
肿瘤学   109篇
  2023年   5篇
  2022年   6篇
  2021年   11篇
  2020年   12篇
  2019年   11篇
  2018年   19篇
  2017年   4篇
  2016年   13篇
  2015年   21篇
  2014年   24篇
  2013年   54篇
  2012年   41篇
  2011年   34篇
  2010年   41篇
  2009年   63篇
  2008年   35篇
  2007年   65篇
  2006年   39篇
  2005年   39篇
  2004年   26篇
  2003年   27篇
  2002年   28篇
  2001年   22篇
  2000年   30篇
  1999年   33篇
  1998年   77篇
  1997年   85篇
  1996年   105篇
  1995年   64篇
  1994年   62篇
  1993年   62篇
  1992年   22篇
  1991年   19篇
  1990年   23篇
  1989年   38篇
  1988年   41篇
  1987年   40篇
  1986年   45篇
  1985年   42篇
  1984年   9篇
  1983年   16篇
  1982年   13篇
  1981年   9篇
  1980年   12篇
  1979年   8篇
  1978年   12篇
  1977年   9篇
  1976年   13篇
  1975年   13篇
  1973年   2篇
排序方式: 共有1547条查询结果,搜索用时 15 毫秒
991.
In this study, blood flow velocity in the basilar artery and both vertebral and middle cerebral arteries was measured with a transcranial Doppler device in 23 migraineurs during and outside a migraine attack. The aim of the study was to compare blood flow velocities during and outside an attack and to examine vascular reactivity to voluntary hyperventilation during both conditions. No differences in blood flow velocity were found. Although blood pressure was increased and end-expiratory CO2 decreased during the attack, this exerted no influence on blood flow velocity. Neither was a difference in vascular reactivity to voluntary hyperventilation detected between the two conditions. These findings support the notion of functional integrity of the examined large arteries during migraine attacks without aura.  相似文献   
992.
993.

Aim

The purpose of the study was to assess the incidence and survival rate of patients with complete atrio-ventricular block in the cardiac centre of St Elizabeth Catholic General Hospital, Kumbo, Cameroon.

Methods

Between 2009 and 2011, 26 patients with complete atrio-ventricular block were diagnosed at our institution. Complete atrio-ventricular block was defined as complete heart block, diagnosed by echocardiographic or electrocardiographic documentation of the dissociation between electrical activity of the atria and ventricles. Hospital charts, electrocardiograms (ECG), echocardiography and chest radiography were reviewed.

Results

The triad of symptoms that pointed to the diagnosis of complete atrio-ventricular block was mainly fatigue, shortness of breath on mild physical exertion, and dizziness. The median age at diagnosis was 65 ± 15 years. The escape rhythm showed a narrow QRS complex in 35.2% of patients, whereas wide QRS complexes were seen in 64.8%. In only 15 patients were pacemakers implanted: dual-chamber in 10 and single-chamber in five cases, depending on the availability of the pacemakers. During the observational period, five non-implanted patients died, giving a mortality rate of 45%. We recorded no deaths in patients with pacemakers.

Conclusion

In developing countries, natural selection is observed in patients with complete atrio-ventricular block. Lack of infrastructure and early detection, and financial limitations are the main problems faced in the follow up of these patients. Re-organisation of the public health system, new programmes for the prevention of cardiovascular diseases, and government subsidisation are needed in our milieu.  相似文献   
994.
BACKGROUND: Onychomycosis is the most frequent nail disease, which could impair the patient's quality of life. OBJECTIVE: The present study was undertaken to evaluate the impact of toenail onychomycosis on quality of life among Polish population. PATIENTS AND METHODS: Three thousand nine-hundred and four (3904: 2269 females and 1635 males) individuals fulfilled an international onychomycosis-specific quality-of-life questionnaire consisting of statements regarding social, emotional and symptoms problems. All patients had toenail onychomycosis confirmed by the positive direct microscopic examination and/or by the positive mycologic culture. Seven hundred and sixty-seven patients simultaneously had fingernail onychomycosis. All patients were divided into subgroups according to sex, age, education level, place of living, type of onychomycosis, number of involved toenails, fingernails involvement, duration of illness and previously used antimycotic therapy. RESULTS: Most of the patients demonstrated significantly reduced quality of life. The degree of life impairment varied between analysed subgroups. Patients with more advanced toenail onychomycosis and with fingernail involvement were more seriously affected. Both social and emotional impairments were more pronounced in female than in male patients, although there were no differences according to symptoms. Moreover, patients with better educational level and people living in towns or cities were more emotionally and socially affected by onychomycosis, although people living in the country or with poorer education level presented with significantly more severe symptoms. CONCLUSIONS: Toenail onychomycosis is still a serious medical problem, which can significantly reduce the patient's quality of life.  相似文献   
995.
<正>To the Editor: Liver tumor may occur in any hepatic segment or lobe, and thus the liver resection is individualized as per the location and size of the tumor. In addition, the resection of the posterior and caudate lobes of the liver is especially difficult amongst all types of hepatectomy. Kawaguchi et al. believed that the laparoscopic resection of right posterior liver lobe was a difficult surgical procedure [1].  相似文献   
996.
997.
Toxaphene (polychlorinated camphenes) is an insecticidal mixture of >670 chemicals, which was widely used until the mid 1980s. Due to their lipophilic and volatile nature, these chemicals accumulate in animal and human tissues and continue to be a major contaminant in marine and freshwater biota. Cytotoxic and genotoxic effects in mammalian test systems suggest that toxaphene is a carcinogen and reports support the hypothesis that toxaphene could have tumor-promoting potential in human breast tissue. In order to examine the potential of toxaphene as an environmental endocrine disrupter, we investigated its effect on the estrogen receptor (ER) function in human breast cancer MCF-7 cells. Using transient gene expression experiments, we observed approximately 60% and 80% inhibition of the constitutive and 17beta-estradiol induced ER-dependent transactivation, respectively. The involvement of the ER in the ability of toxaphene to block the estrogen action was verified by cotransfection studies in ER-negative MDA-MB-231 cells. The interference of toxaphene with the ER mediated responses was supported by a significant suppression of endogenously expressed pS2 RNA and decreased levels of secreted pS2 protein. These reproducible results indicate that toxaphene can disturb hormonal signals mediated by the ER and suggest that these environmental chemicals have potential endocrine disrupting activities which may affect the reproductive health and increase the risk of carcinogenesis.   相似文献   
998.
999.
1000.
AIM: To assess the effect of adding clarithromycin to the combination of omeprazole and amoxycillin for the eradication of H. pylori infection. PATIENTS AND METHODS: In an open, randomized, three-centre study 120 patients (69 men, mean age 47 years, caucasians 74%) with symptoms of dyspepsia had normal gastroscopic examination and a positive urease test. They underwent a 13C-urea breath test and received, for 14 days, either omeprazole 40 mg b.d. plus amoxycillin 750 mg b.d., or the same regimen plus clarithromycin 250 mg b.d. Compliance was assessed by returned tablet counts. H. pylori clearance at the end of treatment and eradication 4 weeks after finishing treatment were assessed by 13C-urea breath test. RESULTS: Results are expressed according to 'all patients treated analysis', excluding patients who did not receive treatment and patients who had no final 13C-urea breath test assessment. In the groups treated with omeprazole- amoxycillin or omeprazole-amoxycillin-clarithromycin good compliance (> or = 90%) was observed in 85% vs. 76% (N.S.) of patients but 25% vs. 34% (N.S.) experienced at least one adverse event. Adverse events were minor, and no patient reported a metallic taste. Four weeks after finishing treatment eradication rates were 26% (95% CI: 15-37%) vs. 93% (95% CI: 86-99%) (P < 0.001). CONCLUSION: These results show that dual therapy with omeprazole plus amoxycillin achieves an unacceptably low H. pylori eradication rate. Addition of clarithromycin at low dosage (250 mg b.d.) proved to be useful, achieving a high eradication rate without increasing side-effects.  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