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   2067篇
  免费   202篇
  国内免费   2篇
耳鼻咽喉   14篇
儿科学   60篇
妇产科学   26篇
基础医学   262篇
口腔科学   48篇
临床医学   244篇
内科学   429篇
皮肤病学   29篇
神经病学   326篇
特种医学   191篇
外科学   196篇
综合类   42篇
一般理论   2篇
预防医学   194篇
眼科学   22篇
药学   117篇
中国医学   1篇
肿瘤学   68篇
  2022年   14篇
  2021年   32篇
  2019年   23篇
  2018年   38篇
  2017年   27篇
  2016年   24篇
  2015年   32篇
  2014年   44篇
  2013年   127篇
  2012年   95篇
  2011年   89篇
  2010年   66篇
  2009年   64篇
  2008年   74篇
  2007年   85篇
  2006年   100篇
  2005年   74篇
  2004年   84篇
  2003年   71篇
  2002年   60篇
  2001年   45篇
  2000年   37篇
  1999年   44篇
  1998年   46篇
  1997年   45篇
  1996年   40篇
  1995年   39篇
  1994年   34篇
  1993年   36篇
  1992年   21篇
  1991年   34篇
  1990年   36篇
  1989年   47篇
  1988年   47篇
  1987年   34篇
  1986年   33篇
  1985年   32篇
  1984年   31篇
  1983年   26篇
  1982年   21篇
  1981年   21篇
  1979年   24篇
  1978年   31篇
  1977年   23篇
  1976年   17篇
  1975年   26篇
  1974年   16篇
  1972年   16篇
  1969年   15篇
  1968年   13篇
排序方式: 共有2271条查询结果,搜索用时 15 毫秒
71.
The clinical, investigative, and surgical findings were reviewed in 47 patients with atrioventricular discordance who presented to the Brompton Hospital between January 1962 and June 1981. Although the unifying feature was the atria connecting to morphologically inappropriate ventricles, the hearts differed widely in other respects. In most cases there was the usual visceral and atrial arrangement, but six had a mirror image arrangement of the atria and viscera. Among those patients with usual atrial arrangement (solitus) the aorta was not always anterior and left sided, and ventricular "inversion" was not invariable. Only 35 of the 47 patients also had a discordant ventriculoarterial connexion, the majority of the remainder having a double outlet right ventricle. The specific diagnosis of atrioventricular discordance depended on echocardiographic and angiographic examination. The other investigations did not distinguish between different ventriculoarterial connexions and were not specific even for the presence of atrioventricular discordance. For those patients with the usual atrial arrangement the anticipated right heart border was present in only just over one third, and the reversal of Q wave progression in the precordial leads of the standard electrocardiogram was found in under a half. Many patients with atrioventricular discordance progressed normally to adult life. In 20 cases no surgery was performed. The results of total correction showed a mortality of 25% (three cases), including two deaths after a modified Fontan procedure for exceedingly complex associated lesions. The results of surgery in the survivors were excellent, and awareness of the disposition of the atrioventricular conduction tissue made it possible to avoid atrioventricular dissociation.  相似文献   
72.
73.
Background:  Several inflammatory biomarkers are implicated in the pathogenesis of periodontitis including interleukin-1β (IL-1β) and C-reactive protein (CRP). This study investigated the presence of these factors in gingival crevicular fluid (GCF) and their relationship to clinical and social determinants of periodontitis in the Australian population.
Methods:  Equal numbers of periodontitis cases and non-cases were sampled during oral epidemiologic examination in the National Survey of Adult Oral Health. GCF was sampled from four sites where probing pocket depth (PPD) and recession were recorded. From these, IL-1β and CRP were quantified by ELISA and the log amount of GCF IL-1β (pg) per person and the proportion of adults with detectable CRP was computed.
Results:  Periodontitis cases (n = 511) had significantly higher levels of IL-1β and CRP than non-cases (n = 562). PPD, clinical attachment loss, plaque and gingivitis indices were positively associated with elevated levels of both biomarkers. Levels of both were positively associated with age, low socio-economic position and non-Australian birth.
Conclusions:  The presence of IL-1β and CRP in GCF are associated with periodontal disease parameters within the Australian population. The levels of both biomarkers are influenced by age, education and eligibility for public dental care.  相似文献   
74.
BackgroundPrevious studies evaluating weight changes following total knee arthroplasty (TKA) were performed on heterogenous cohorts. However, no study has evaluated weight changes in a cohort of simultaneous-bilateral TKA (SB-TKA) patients. This study aimed to evaluate the prevalence of patients who lost or gained weight, determine if postoperative weight change influences functional outcome, and identify predictors of weight change after SB-TKA.MethodsProspectively collected registry data of 560 patients who underwent SB-TKA were reviewed. Patients were assessed preoperatively, at 6 months, and 2 years using the Knee Society Score, Oxford Knee Score, Short-Form 36, and range of motion. Change in body mass index (BMI) >5% was used to categorize patients into 3 groups: lost, maintained, or gained weight. Analysis of variance, Kruskal-Wallis test, and chi-squared test were used to compare functional outcomes between groups. Multivariable logistic regression evaluated predictors for postoperative weight changes.ResultsAt 2 years, 59% of patients maintained weight, 28% of patients gained weight, and 13% of patients lost weight. All groups experienced similar improvements in functional outcomes, rates of minimal clinically important difference attainment, and patient satisfaction (P > .05). Older patients were more likely to gain weight (P < .05). Patients with higher preoperative BMI were more likely to gain weight (P < .05) and less likely to lose weight (P < .05). Patients with greater preoperative comorbidities were less likely to lose weight (P < .05).ConclusionUp to 41% of patients experience significant weight changes after SB-TKA. Older patients with higher preoperative BMI were more likely to gain weight, while higher preoperative BMI with more comorbidities were less likely to lose weight following SB-TKA; however, postoperative weight changes do not appear to affect functional outcomes.Level of EvidenceIII, therapeutic study.  相似文献   
75.
BACKGROUND: Although some pediatric cardiology departments have a policy of adopting primary correction of tetralogy of Fallot in all symptomatic infants, we and others still palliate neonates and infants. Effective palliation should ameliorate symptoms and allow growth of the pulmonary arteries. Although studies on the growth of the ipsilateral and contralateral pulmonary arteries after a classic Blalock-Taussig shunt have been reported, pulmonary artery growth after a modified Blalock-Taussig shunt has not been studied as thoroughly. Therefore, we examined whether there is equal growth of the contralateral pulmonary artery after a modified Blalock-Taussig shunt. METHODS: We retrospectively analyzed the records of 140 patients with symptomatic tetralogy of Fallot who had a modified Blalock-Taussig shunt between October 1985 and October 1995. The median age at the time of the Blalock-Taussig shunt was 1.6 months. All patients had corrective procedures at a median age of 1.7 years. Cineangiography was done before the corrective procedure. From the angiograms the diameter of the right and left pulmonary arteries before their first lobar branches and the diameter of the descending thoracic aorta at the level of the diaphragm were measured. For each patient the ratios of right pulmonary artery to descending thoracic aorta and left pulmonary artery to descending thoracic aorta were determined and compared using Student's t test. RESULTS: Of the 140 patients, 114 had a left-sided Blalock-Taussig shunt, 20 had a right-sided shunt, and 6 patients had bilateral shunts. The mean right pulmonary artery to descending thoracic aorta ratio was 1.10 and the mean left pulmonary artery to descending thoracic aorta ratio was 0.98. This difference was not significant. CONCLUSION: We showed equal growth of the right and left pulmonary arteries with no distortion after a modified Blalock-Taussig shunt. If palliation is considered, the modified Blalock-Taussig shunt remains our choice.  相似文献   
76.
Previous research of negative symptoms in schizophrenia has emphasized an anticipatory pleasure deficit, yet the relationship of this deficit to patients' motivation in everyday life is poorly understood. This study tested the link between anticipatory pleasure and two broad motivational systems that are said to regulate the intensity of approach and avoidance behavior, the Behavioral Inhibition system (BIS) and the Behavioral Activation System (BAS). It was hypothesized that high vulnerability for negative symptoms would be associated with low reward responsiveness and that this association will be mediated by the amount of anticipated pleasure. Students (n=171) with varying vulnerability for negative symptoms (assessed by the Community Assessment of Psychic Experiences) completed questionnaires regarding (a) anticipatory and consummatory pleasure, and (b) responsiveness to threat and reward. As hypothesized, anticipatory pleasure correlated significantly negatively with subclinical negative symptoms (r=−0.21) and significantly positively with BAS (r=0.55). Furthermore, evidence for a partial mediation effect was found. The findings support the notion of a close association between negative symptoms, the ability to anticipate pleasure and approach motivation that is evident even in healthy persons. It is suggested that the behavioral deficits immanent to negative symptoms reflect difficulties in the ability to translate emotions into motivation.  相似文献   
77.
Twenty-six patients (4 months to 6 years old) with achondroplasia complicated by sleep apnea and/or other neurologic manifestations underwent plain computed tomography (CT) of the craniocervical junction; six also underwent CT myelography. For objectification, multiplanar reconstruction was used to complement axial plane measurements by providing coronal and sagittal measurements; multiplanar reconstruction also improved perception of the longitudinal relationships between the brain stem and subarachnoid space. A narrow subarachnoid space was found in all 26 patients; marked cord compression was present in nine, six of whom underwent CT myelography. These six had marked focal obliteration of the subarachnoid space on both plain CT and CT myelography. Since the subarachnoid space immediately above and below the craniocervical junction is normally capacious, when marked constriction was present, no additional information could have been gained from CT myelography. Thus, plain CT was shown to be sufficient for surgical planning (suboccipital decompression) in nine patients with cord compression due to achondroplasia.  相似文献   
78.

Purpose

This study examined the relationship between informal social support from extended family and friends and suicidality among African Americans.

Methods

Logistic regression analysis was based on a nationally representative sample of African Americans from the National Survey of American Life (N = 3263). Subjective closeness and frequency of contact with extended family and friends and negative family interaction were examined in relation to lifetime suicide ideation and attempts.

Results

Subjective closeness to family and frequency of contact with friends were negatively associated with suicide ideation and attempts. Subjective closeness to friends and negative family interaction were positively associated with suicide ideation and attempts. Significant interactions between social support and negative interaction showed that social support buffers against the harmful effects of negative interaction on suicidality.

Conclusions

Findings are discussed in relation to the functions of positive and negative social ties in suicidality.
  相似文献   
79.
Circadian blood pressure variation after acute stroke.   总被引:2,自引:0,他引:2  
We aimed to characterise the patterns of circadian blood pressure (BP) variation after acute stroke and determine whether any relationship exists between these patterns and stroke outcome. BP was recorded manually every 4 h for 48 h following acute stroke. Patients were classified according to the percentage fall in mean systolic BP (SBP) at night compared to during the day as: dippers (fall > or = 10-<20%); extreme dippers (> or = 20%); non-dippers (> or = 0-<10%); and reverse dippers (<0%, that is, a rise in mean nocturnal SBP compared to mean daytime SBP). One hundred and seventy-three stroke patients were included in the study (83 men, 90 women; mean age 74.3 years). Four patients (2.3%) were extreme dippers, 25 (14.5%) dippers, 80 (46.2%) non-dippers and 64 (36.9%) reverse dippers. There was a non-significant trend in the proportion of patients who were dead or dependent at 3 months in the extreme dipper (p=0.59) and reverse dipper (p=0.35) groups. Non-dipping and reverse-dipping were relatively common patterns of circadian BP variation seen in acute stroke patients. These patterns were not clearly associated with outcome.  相似文献   
80.
The present study explored the prevalence of anxiety disorders among adults seeking speech therapy for stuttering. Employing a matched case–control design, participants included 92 adults seeking treatment for stuttering, and 920 age- and gender-matched controls from the Australian National Survey of Mental Health and Well-being. A conditional logistic regression model was used to estimate odds ratios for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) and International Classification of Diseases (ICD-10) anxiety disorders. Compared with matched controls, the stuttering group had six- to seven-fold increased odds of meeting a 12-month diagnosis of any DSM-IV or ICD-10 anxiety disorder. In terms of 12-month prevalence, they also had 16- to 34-fold increased odds of meeting criteria for DSM-IV or ICD-10 social phobia, four-fold increased odds of meeting criteria for DSM-IV generalized anxiety disorder, and six-fold increased odds of meeting criteria for ICD-10 panic disorder. Overall, stuttering appears to be associated with a dramatically heightened risk of a range of anxiety disorders.  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