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   3087篇
  免费   160篇
  国内免费   21篇
耳鼻咽喉   63篇
儿科学   88篇
妇产科学   29篇
基础医学   524篇
口腔科学   39篇
临床医学   343篇
内科学   821篇
皮肤病学   30篇
神经病学   315篇
特种医学   72篇
外科学   254篇
综合类   12篇
一般理论   3篇
预防医学   228篇
眼科学   21篇
药学   200篇
中国医学   4篇
肿瘤学   222篇
  2023年   23篇
  2022年   32篇
  2021年   49篇
  2020年   49篇
  2019年   59篇
  2018年   67篇
  2017年   58篇
  2016年   89篇
  2015年   64篇
  2014年   105篇
  2013年   165篇
  2012年   195篇
  2011年   225篇
  2010年   127篇
  2009年   105篇
  2008年   186篇
  2007年   180篇
  2006年   208篇
  2005年   193篇
  2004年   143篇
  2003年   135篇
  2002年   125篇
  2001年   32篇
  2000年   34篇
  1999年   32篇
  1998年   34篇
  1997年   33篇
  1996年   29篇
  1995年   28篇
  1994年   27篇
  1993年   31篇
  1992年   30篇
  1991年   22篇
  1990年   15篇
  1989年   19篇
  1988年   24篇
  1987年   17篇
  1986年   15篇
  1985年   33篇
  1984年   15篇
  1983年   14篇
  1982年   21篇
  1980年   9篇
  1979年   12篇
  1978年   12篇
  1975年   12篇
  1973年   9篇
  1972年   14篇
  1971年   13篇
  1966年   8篇
排序方式: 共有3268条查询结果,搜索用时 15 毫秒
71.
72.
Little is known about the combined associations of cardiorespiratory fitness (CRF) and hand grip strength (GS) with mortality in general adult populations. The purpose of this study was to compare the relative risk of mortality for CRF, GS, and their combination. In UK Biobank, a prospective cohort of >?0.5 million adults aged 40–69 years, CRF was measured through submaximal bike tests; GS was measured using a hand-dynamometer. This analysis is based on data from 70,913 men and women (832 all-cause, 177 cardiovascular and 503 cancer deaths over 5.7-year follow-up) who provided valid CRF and GS data, and with no history of heart attack/stroke/cancer at baseline. Compared with the lowest CRF category, the hazard ratio (HR) for all-cause mortality was 0.76 [95% confidence interval (CI) 0.64–0.89] and 0.65 (95% CI 0.55–0.78) for the middle and highest CRF categories, respectively, after adjustment for confounders and GS. The highest GS category had an HR of 0.79 (95% CI 0.66–0.95) for all-cause mortality compared with the lowest, after adjustment for confounders and CRF. Similar results were found for cardiovascular and cancer mortality. The HRs for the combination of highest CRF and GS were 0.53 (95% CI 0.39–0.72) for all-cause mortality and 0.31 (95% CI 0.14–0.67) for cardiovascular mortality, compared with the reference category of lowest CRF and GS: no significant association for cancer mortality (HR 0.70; 95% CI 0.48–1.02). CRF and GS are both independent predictors of mortality. Improving both CRF and muscle strength, as opposed to either of the two alone, may be the most effective behavioral strategy to reduce all-cause and cardiovascular mortality risk.  相似文献   
73.
The duration of untreated ventricular fibrillation (VF) is of paramount importance for CPR success. Moreover, therapeutic interventions taking into account the interval between cardiac arrest onset and initiation of CPR improve outcome. This study was performed to investigate whether VF feature analysis could be used to estimate the duration of VF in patients with out-of-hospital cardiac arrest. Demographic data recorded according to the Utstein guidelines and ECG recordings of 376 cardiac arrest patients from three European areas were analysed. Ten features in the time and frequency domain derived from different sub-bands of the initial VF ECG (n=127) were evaluated. The correlation between VF ECG features and cardiac arrest times was investigated using Pearson's correlation coefficient in a subset of 40 patients with reliably estimated downtimes and artefact-free initial VF tracings. No significant correlation (p<.05) between any of the VF ECG features and downtime could be found. The duration of cardiac arrest could not be estimated reliably from human VF ECG single feature analysis.  相似文献   
74.
Disorganized behavior is a key symptom of schizophrenia. The objective assessment of disorganized behavior is particularly challenging. Actigraphy has enabled the objective assessment of motor behavior in various settings. Reduced motor activity was associated with negative syndrome scores, but simple motor activity analyses were not informative on other symptom dimensions. The analysis of movement patterns, however, could be more informative for assessing schizophrenia symptom dimensions. Here, we use time series analyses on actigraphic data of 100 schizophrenia spectrum disorder patients. Actigraphy recording intervals were set at 2 s. Data from 2 defined 60-min periods were analyzed, and partial autocorrelations of the actigraphy time series indicated predictability of movements in each individual. Increased positive syndrome scores were associated with reduced predictability of movements but not with the overall amount of movement. Negative syndrome scores were associated with low activity levels but unrelated with predictability of movement. The factors disorganization and excitement were related to movement predictability but emotional distress was not. Thus, the predictability of objectively assessed motor behavior may be a marker of positive symptoms and disorganized behavior. This behavior could become relevant for translational research.Key words: schizophrenia, actigraphy, behavior, time series analysis, positive symptoms, negative symptoms  相似文献   
75.
76.

Purpose

The aim of this observational study was to describe the type, number, and serum concentration levels of psychotropic drugs in elderly patients, on admission to a geriatric psychiatric inpatient unit. We further wanted to investigate the use and unreported use of psychotropic drugs by analyzing for a broad spectrum of drugs in the serum samples.

Methods

A total of 236 patients were included. Drug use, patient characteristics, and diagnoses were recorded, and serum analysis was performed for a total of 56 psychotropic drugs in 233 of the patients.

Results

Nine out of ten patients (88 %) used one or more psychotropic drugs on admission to hospital; the mean use was 2.8 (95 % confidence interval (CI) 2.6–2.9) drugs. In 25 patients (11 %), drugs reported used were not detected in serum. Unreported use of drugs (serum analysis revealing one or more drugs not reported) was found in 100 patients (43 %). This was more common in younger patients. Psychotropic polypharmacy (use of three or more psychotropic drugs) was found in 109 patients (47 %). Patients with a main diagnosis of affective disorder used the most psychotropic drugs.

Conclusions

Psychotropic drugs are commonly used among geriatric psychiatric patients on admission to hospital. Psychotropic polypharmacy is a major concern among these patients. There was considerable unreported use of drugs within this population, and a low threshold for a broader serum analysis for psychotropic drugs appears indicated.  相似文献   
77.
78.
Reflux from the continent ileostomy reservoir   总被引:1,自引:0,他引:1  
The reflux from the continent ileostomy reservoir was studied with radiologic and pressure recording techniques in ten patients. The contrast used was poly-iodine-styrene with a density of 0.8 to 1.1 gm/cm3. Reflux into the afferent loop was demonstrated in all patients at a filling volume of approximately 30 percent of the maximal volume capacity of the reservoir. The magnitude of reflux increased with the increasing volume of the reservoir contents and a rise in reservoir pressure. The reflux could temporarily be influenced by antiperistaltic or isoperistaltic motor activity in the afferent loop. Although no adverse effects were seen from the amount of reflux demonstrated in the present investigation, the finding of increasing reflux with increased fullness and intraluminal pressure of the reservoir would indicate that the reservoir should be emptied at regular intervals and before high pressures are built up.  相似文献   
79.

Background:

The long-term prognosis of repeated acute episodes of hypersensitivity pneumonitis (HP) is not well described. We report on a 10-year follow-up of a 10-person cluster from a Norwegian sawmill who had all experienced relapsing episodes of HP.

Objectives:

To evaluate the health symptoms, work-related sick-leave, and lung function of 10 workers exposed to mold in a Norwegian sawmill.

Methods:

Participants were evaluated at baseline and 10 years later at follow-up. A structured interview, measurement of serum IgG antibodies to Rhizopus microsporus (R. microsporus) antigens, lung function tests, high resolution computed tomography (HRCT) of the chest, and personal measurements of exposure to mold spores and dust were completed for each participant.

Results:

At baseline, nearly all workers reported acute episodes of HP more than twice a month. At follow-up, both the frequency and intensity of symptoms had declined. Sick-leave was reduced and gas diffusing capacity improved – paralleling the gradually reduced air levels of mold spores.

Conclusions:

In spite of an initially high occurrence of symptoms, long-term clinical and physiological outcome was good. With reduced exposure to mold spores, symptoms declined and lung function was restored.  相似文献   
80.
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