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   1245篇
  免费   81篇
  国内免费   3篇
耳鼻咽喉   2篇
儿科学   85篇
妇产科学   11篇
基础医学   163篇
口腔科学   50篇
临床医学   118篇
内科学   317篇
皮肤病学   21篇
神经病学   51篇
特种医学   257篇
外科学   66篇
综合类   13篇
一般理论   1篇
预防医学   78篇
眼科学   4篇
药学   51篇
中国医学   1篇
肿瘤学   40篇
  2023年   3篇
  2022年   4篇
  2021年   4篇
  2019年   4篇
  2018年   16篇
  2017年   12篇
  2016年   11篇
  2015年   16篇
  2014年   18篇
  2013年   21篇
  2012年   19篇
  2011年   12篇
  2010年   37篇
  2009年   46篇
  2008年   36篇
  2007年   35篇
  2006年   33篇
  2005年   29篇
  2004年   32篇
  2003年   28篇
  2002年   21篇
  2001年   22篇
  2000年   19篇
  1999年   22篇
  1998年   55篇
  1997年   72篇
  1996年   52篇
  1995年   46篇
  1994年   56篇
  1993年   59篇
  1992年   23篇
  1991年   22篇
  1990年   22篇
  1989年   46篇
  1988年   51篇
  1987年   47篇
  1986年   38篇
  1985年   44篇
  1984年   19篇
  1983年   30篇
  1982年   24篇
  1981年   21篇
  1980年   22篇
  1979年   8篇
  1978年   10篇
  1977年   13篇
  1976年   11篇
  1975年   21篇
  1974年   4篇
  1968年   2篇
排序方式: 共有1329条查询结果,搜索用时 0 毫秒
101.
Several epidemiological studies described poor asthma control in children. However, the diagnosis of childhood asthma in these studies is uncertain, and asthma control in children of an outpatient clinic population during treatment by a paediatrician is unknown. (1) to investigate the hypothesis that asthma control in a paediatric outpatient clinic population is better than epidemiological surveys suggest; (2) to find possible explanations for suboptimal asthma control. Asthmatic children aged 6–16 years, known for at least 6 months by a paediatrician at the outpatient clinic, were selected. During a normal visit, both the responsible physicians and parent/children completed a standardised questionnaire about asthma symptoms, limitation of daily activities, treatment, asthma attacks and emergency visits. Overall, excellent asthma control of 8.0% in this study was not significantly better than of 5.8% in the European AIR study (Chi‐square, p = 0.24). Separate GINA goals like minimal chronic symptoms and no limitation of activities were better met in our study. Good to excellent controlled asthma was perceived by most children/parents (83%), but was less frequently indicated by the paediatrician (73%), or by objective criteria of control (45%) (chi‐square, p = 0.0001). The agreement between patient‐perceived and doctor assessed control was low, but improved in poorly controlled children. Patients were not able to perceive the difference between ‘excellent asthma control’ and ‘good control’ (p = 0.881).Too little children with uncontrolled disease got step‐up of their asthma treatment. Although separate GINA goals like ‘minimal chronic symptoms’ and ‘no limitation of activities’ were significantly better in our study, overall, asthma control in this outpatient clinic population, treated by a paediatrician, was not significantly better than in the European AIR study. Poorly controlled disease was related to several aspects of asthma management, which are potentially accessible for improvements.  相似文献   
102.
This multicentre, double-blind, randomized, placebo-controlled, parallel study was designed to evaluate the efficacy of combined oral lysine acetylsalicylate and metoclopramide (LAS-MCP) in the acute treatment of migraine attacks. A total of 266 patients, 18–65 years old, with two to six attacks of migraine with or without aura (IHS criteria) per month were included. The patients had to treat two migraine attacks with LAS-MCP (1620 mg lysine acetylsalicylate-the equivalent of 900 mg aspirin- combined with 10 mg metoclopramide) or placebo. The main outcome measure was headache relief (reduction in headache severity from grade 3 or 2-severe or moderate-to grade 1 or 0-mild or none) 2 h after treatment. LAS-MCP was superior to placebo for headache relief (56% vs 28%) and for the following secondary outcome measures: complete headache relief (18% vs 7%; p < 0.001), nausea (28% vs 44%; p < 0.001), vomiting (3% vs 11%; p = 0.001), use of rescue medication (47% vs 68%; p < 0.001), global efficacy judged as good or excellent (32% vs 14%; p < 0.001). The tolerability was considered as good in 94% of treated attacks in both groups. Combined oral lysine acetylsalicylate and metoclopramide is an effective and well-tolerated acute treatment of migraine attacks.  相似文献   
103.
Growth factors have been identified as the primary cause of osteoinduction in bone healing. Transforming growth factor beta (TGF- beta) has been shown to promote bone formation and is present in bone in high quantities. The aims of the present study were to isolate TGF- beta from human bone, demonstrate its biologic activity, and analyze the effects of conventional sterilization techniques on activity. Bone, obtained from femoral heads of five patients (mean age, 70 years) was ground, demineralized, and freeze-dried, and samples from each patient were divided into three groups: no treatment, sterilization with 1.60 to 1.94 Mrad of 60Co irradiation, and sterilization with ethylene oxide (ETO). Carrier-free recombinant TGF-beta control was also treated and was totally inactivated by ETO but not by irradiation (p < 0.01). TGF- beta activity in demineralized bone was not significantly diminished (p > 0.1) by either sterilization procedure, and substantial amounts of active TGF-beta were recovered in all bone samples: 1.04 +/− 0.77 ng per mg of protein in irradiated samples, 0.67 +/− 0.26 ng per mg in ETO- treated samples, and 1.04 +/− 0.33 in untreated samples, respectively (mean +/− SD). Although a recent report demonstrated that the osteoinductive activity of bone morphogenetic protein in bone powder is diminished considerably by ETO and by 2.5 Mrad of irradiation sterilization of bone powder, these data demonstrate that TGF-beta activity, with its osteoinductive properties, was not destroyed in more coarsely ground, demineralized bone by ETO or by lower doses of irradiation. These findings support the use of human bone allografts in clinical instances involving impaired bone formation.  相似文献   
104.

Background

Diagnostic ultrasonography is used by GPs in approximately 10% of patients of reproductive age with abnormal vaginal bleeding. Transvaginal sonography is recommended as a first-line diagnostic instrument for assessing uterine pathology.

Aim

To assess if findings resulting from openaccess sonography were in agreement with the GPs’ working hypotheses and if these findings contributed to GPs’ management.

Design and setting

Prospective observational cohort study of GPs working in the health district of the Academic Medical Center, Amsterdam and their patients consulting with abnormal vaginal bleeding.

Method

Data on patients’ history, GPs’ primary working hypotheses, and intended management were recorded. After sonography, GPs recorded their actual management.

Results

A total of 122 patients were included by 18 GPs from June 2003 to December 2004. Data from 89 patients were available for analysis. The GPs’ working hypotheses implied ‘no structural pathology’ in 65/89 patients, and ‘fibroids’ in 24/89 patients. Sonographic findings were confirmed in 50/65 patients where ‘no structural pathology’, and in 14/24 of those where ‘fibroids’ were expected. Initially, GPs had intended to refer nine patients to a gynaecologist. Actual management after sonographic assessment was watchful waiting or drug therapy in 57/89 patients. Eighty-nine per cent of these patients had normal sonographic findings. The actual referral rate rose to 27/89 patients. In 17 referred patients, sonographic findings were suggestive of intracavitary abnormalities.

Conclusion

Open-access sonography contributed to more accurate diagnoses and improved GPs’ management of women with abnormal vaginal bleeding.  相似文献   
105.
106.
Several studies have suggested that there may be an increased prevalence of affective disorders in people with motor neuron disease (MND). However, the literature is inconsistent, possibly because of small sample sizes in the existing studies. The Canadian province of Alberta has a universal health care system in which physician contacts are recorded along with ICD-9-CM diagnostic codes. In this analysis, diagnostic codes indicative of MND and affective disorders were used. Stratified analysis and logistic regression were used in the analysis. There were 336 cases of MND leading to a prevalence of 14.5 per 100,000 in provincial residents > or =20 years old. Affective disorders were identified in 8.6% of the total population during the same year. The crude odds ratio for affective disorders in MND was 2.3 (95% CI = 1.7-3.0). However, the prevalence of affective disorders declined with increasing illness duration.  相似文献   
107.
A deletion on one chromosome and a mutant allele on the other may cause an autosomal recessive disease. We report on two patients with mental retardation, dysmorphic features and low catalytic activity of arylsulfatase A. One patient had a pathogenic mutation in the arylsulfatase A gene ( ARSA ) and succumbed to metachromatic leukodystrophy (MLD). The other patient had a pseudoallele, which does not lead to MLD. The presenting clinical features and low arylsulfatase A activity were explained, in each patients, by a deletion of 22q13 and, thereby, of one allele of ARSA .  相似文献   
108.

Background and purpose:

In vitro evidence suggests that metabolism of anandamide by cyclooxygenase-2 (COX-2) may be more important when the primary metabolic pathway [i.e. fatty acid amide hydrolase (FAAH)] is inhibited. Thus, the first aim of the present study was to assess the effects of COX-2 and/or FAAH inhibition, on the cardiovascular actions of anandamide. The second aim was to compare the effects of anandamide with those of the metabolically stable analogue (i.e. methanandamide) and investigate mechanisms involved in responses to the latter in conscious rats.

Experimental approach:

Rats were chronically instrumented for recording blood pressure, heart rate and renal, mesenteric and hindquarters vascular conductances in the freely moving state.

Key results:

Inhibition of FAAH with URB597 (cyclohexycarbamic acid 3′-carbamoyl-biphenyl-3-yl-ester) augmented the haemodynamic actions of anandamide, but there was no effect of COX-2 inhibition with parecoxib, either in the absence or the presence of URB597. Methanandamide caused CB1 receptor-mediated renal and mesenteric vasoconstriction and evoked β2-adrenoceptor-mediated hindquarters vasodilatation.

Conclusions and implications:

No evidence for an involvement of COX-2 in the systemic cardiovascular actions of anandamide could be demonstrated. Vasoconstrictor actions of methanandamide were shown to involve CB1 receptors, whereas no involvement of CB1 receptors in such actions of anandamide has been shown. However, β2-adrenoceptor-mediated hindquarters vasodilatation, independent of CB1 receptors, observed here with methanandamide, has previously been seen with anandamide and differs from previous results with other synthetic cannabinoids for which the response was CB1 receptor-dependent. Thus, mechanisms underlying the cardiovascular actions of endocannabinoids and synthetic analogues appear to be agonist-specific.  相似文献   
109.

Introduction

Hypertension is prevalent in the general population. Emergency Department (ED) follow-up studies show persistence of blood pressure elevations in up to 50% of patients, and ED screening for hypertension has been recommended. Blood pressure elevations are often ignored or attributed to pain or anxiety. Our purpose was to document the incidence and recognition of hypertension in the ED and to assess its relation to pain scores and age.

Methods

This was a retrospective study. Patients presenting to the ED during a 1-month period were included. Age, blood pressure, and pain scores were reviewed. Discharge instructions and diagnoses were assessed as to whether blood pressure was recognized or follow-up was recommended.

Results

There were 2821 patients. Fifteen percent were less than 18 years old. Twenty-six percent had an elevated blood pressure (40% of pediatric patients). There was no correlation between the distribution of pain scores in either children or adults. There was almost no recognition of the problem. Follow-up for elevated blood pressure was recommended in only 4%. Of these, only 46% actually received follow-up. Twenty-four percent of patients with elevated blood pressure received follow-up for other reasons. Blood pressure was still elevated in 47%.

Conclusion

Hypertension was a common problem in our patient population. Elevated blood pressure readings were almost uniformly ignored or unrecognized, particularly in children. There was no correlation of elevated blood pressure readings and acute pain scores. Elevated blood pressure readings should not be attributed solely to anxiety or acute pain on presentation.  相似文献   
110.
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