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   10245篇
  免费   940篇
  国内免费   16篇
耳鼻咽喉   98篇
儿科学   251篇
妇产科学   370篇
基础医学   1587篇
口腔科学   111篇
临床医学   792篇
内科学   2023篇
皮肤病学   493篇
神经病学   1038篇
特种医学   349篇
外科学   1339篇
综合类   69篇
一般理论   2篇
预防医学   1050篇
眼科学   99篇
药学   834篇
中国医学   37篇
肿瘤学   659篇
  2023年   83篇
  2022年   91篇
  2021年   163篇
  2020年   138篇
  2019年   191篇
  2018年   201篇
  2017年   186篇
  2016年   192篇
  2015年   214篇
  2014年   234篇
  2013年   442篇
  2012年   525篇
  2011年   502篇
  2010年   309篇
  2009年   299篇
  2008年   470篇
  2007年   406篇
  2006年   469篇
  2005年   435篇
  2004年   437篇
  2003年   380篇
  2002年   336篇
  2001年   310篇
  2000年   329篇
  1999年   297篇
  1998年   133篇
  1997年   94篇
  1996年   105篇
  1995年   111篇
  1994年   96篇
  1993年   83篇
  1992年   206篇
  1991年   218篇
  1990年   200篇
  1989年   221篇
  1988年   202篇
  1987年   189篇
  1986年   164篇
  1985年   170篇
  1984年   140篇
  1983年   106篇
  1982年   88篇
  1981年   67篇
  1979年   102篇
  1978年   75篇
  1977年   80篇
  1976年   62篇
  1975年   62篇
  1974年   65篇
  1973年   68篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
OBJECTIVES: The study investigated if patient and informant reported Quality of Life (QoL) differed in early Alzheimer's disease (AD). In addition, we examined whether anosognosia had an impact on the agreement between patient and informant ratings of QoL and whether anosognosia, dementia severity, depression and behavioural symptoms were significantly correlated to QoL in early AD. METHODS: From a prospective research program including newly referred patients (age >60 years and MMSE > or = 20), 48 patients with very early AD were included. QoL was assessed using the QoL-AD and EQ-5D scales. Anosognosia was rated on a categorical scale by an examiner. MMSE, Geriatric Depression Scale, Danish Adult Reading Test and Frontal Behavioural Inventory were also administered. RESULTS: On most QoL measures patients rated their QoL higher than their informants. Anosognosia was not associated with QoL but significantly with an inverse impact on the agreement between patient and informant ratings of QoL. Self-reported QoL was significantly correlated to depression but not to age, dementia severity, behavioural symptoms or memory impairment. Informant ratings of QoL were significantly correlated to behavioural symptoms and informant ratings on the EQ-5D Visual Analogue Scale were significantly correlated to patient reported depression. CONCLUSION: Patients with early AD generally reported higher QoL than their informants. This disagreement was associated with the presence of anosognosia. Self-reported QoL did not correlate with the MMSE score. Behavioural changes and depressive symptoms may be associated with low QoL.  相似文献   
102.
103.
Post-transplant lymphoproliferative disease remains a complication with a high morbidity and mortality. The present study examined 291 pediatric liver transplants performed in 263 children from October 1984 to December 1999. Post-transplant lymphoproliferative disease has an overall incidence of 12%. Tacrolimus and cyclosporine had a similar incidence of post-transplant lymphoproliferative disease. Fifty-six per cent of patients who developed post-transplant lymphoproliferative disease were Epstein-Barr virus negative at the time of transplantation. Mean time of conversion to Epstein-Barr virus positivity was 1.1 years after liver transplantation. Ten per cent of those who developed post-transplant lymphoproliferative disease never had Epstein-Barr virus detected. Mean time from Epstein-Barr virus positivity to detection of post-transplant lymphoproliferative disease was 2.68 years, and 3.13 years from liver transplantation (OLTx) to post-transplant lymphoproliferative disease. There was a 35% incidence of mortality. Deaths occurred a mean of 0.76 years after diagnosis of post-transplant lymphoproliferative disease. Most cases of post-transplant lymphoproliferative disease had extranodal location. There was one recurrence in 10% of patients, and two in 3%. All recurrent cases were seen in recipients who became Epstein-Barr virus positive after transplantation. There has been a decrease in the incidence of post-transplant lymphoproliferative disease from 15% to 9% to 4%. Post-transplant lymphoproliferative disease should be diagnosed promptly and treated aggressively. The best treatment, however, seems to be prevention, starting in the immediate postoperative period. Survivors should be monitored for both recurrence of post-transplant lymphoproliferative disease and acute cellular rejection.  相似文献   
104.
BACKGROUND: The cardiovascular response to a volume challenge with hydroxyethyl starch (HES) (200/0.5) 6% depends on the relation between the volume of HES 6% infused and the expansion of the blood volume in critically ill patients. However, only relatively limited data exist on the plasma expanding effect of infusion of HES 6% in critically ill patients. The purpose of the study was to evaluate the variation in the expansion of the circulating blood volume (CBV) in critically ill patients after infusion of 500 ml of colloid (HES (200/0.5) 6%) using the carbon monoxide method. METHODS: In 20 consecutive patients admitted to the ICU requiring mechanical ventilation and volume expansion, 500 ml of HES (200/0.5) 6% was infused. The CBV was measured immediately before the infusion, 10 min after completing the infusion and then hourly for 8 h. RESULTS: The median volume expansion immediately after infusion was 470 ml (range 270 ml to 840 ml). The corresponding values after 4 h and 8 h were 265 ml (range -30 ml to 460 ml) and 120 ml (range -210 ml to 360 ml), respectively. The increase in CBV was only statistically significant for 4 h. The coefficient of variation of the method for estimation of CBV was 3.6%. CONCLUSIONS: The large interindividual variation of the volume expansion after infusion of HES 6% in critically ill patients illustrates one of the difficulties in optimizing colloid therapy and interpretating the changes in hemodynamic variables after a colloid challenge.  相似文献   
105.
We systematically reviewed randomised controlled trials of peri‐operative melatonin. We included 24 studies of 1794 participants that reported eight peri‐operative outcomes: anxiety; analgesia; sleep quality; oxidative stress; emergence behaviour; anaesthetic requirements; steal induction; and safety. Compared with placebo, melatonin reduced the standardised mean difference (95% CI) pre‐operative anxiety score by 0.88 (0.44–1.33) and postoperative pain score by 1.06 (0.23–1.88). The magnitude of effect was unreliable due to substantial statistical heterogeneity, with I2 87% and 94%, respectively. Qualitative reviews suggested the melatonin improved sleep quality and emergence behaviour, and might be capable of reducing oxidative stress and anaesthetic requirements.  相似文献   
106.

Background

A person's confidence to control eating, eating self-efficacy (ESE), has been identified as a target for long-term weight management in nonsurgical weight loss interventions, but has to a limited extent been studied after bariatric surgery.

Objective

We investigated the association between ESE, weight loss, and obesity-specific quality of life (QOL) after sleeve gastrectomy (SG).

Setting

A single-center longitudinal study.

Methods

Data from adult patients were collected before SG, and at mean 16 months (±standard deviation 4 mo) and 55 (±4) months postoperatively. ESE was measured by the Weight Efficacy Lifestyle Questionnaire Short-Form. Multiple regression analyses were performed with excess body mass index loss (%EBMIL) and obesity-specific QOL as dependent variables. Age, sex, and other preoperative values were covariates in all models.

Results

Of 114 preoperative patients, 91 (80%) and 84 (74%) were available for follow-up 16 and 55 months after SG, respectively. Mean %EBMIL from baseline to 16 and 55 months was 76% (95% confidence interval: 71.9, 79.6) and 67% (95% confidence interval: 61.9, 72.2), respectively. Preoperative ESE scores improved significantly at both 16 and 55 months (P?=?.002) but did not predict postoperative %EBMIL or QOL at 55 months (β?=??.08, P?=?.485). Greater change in ESE from 0 to 16 months predicted higher %EBMIL (β?=?.34, P?=?.013) at 55 months, and improvements in ESE from 0 to 55 months were significantly associated with higher %EBMIL (β?=?.46, P?=?.001) and obesity-specific QOL (β?=?.50, P < .001) 55 months after SG.

Conclusion

Significant improvements in ESE were seen at 16 months, and remained high at 55 months after SG in this cohort. Patients who improved their ESE the most also experienced the highest weight loss and obesity-specific QOL 5 years postoperatively. Future research should address whether enhancement of ESE corresponds to sustained improvements in eating behavior after bariatric surgery.  相似文献   
107.
We report a rare case of a secondary aortoesophageal fistula discovered incidentally during elective upper endoscopy. The patient had previously undergone repair of a descending thoracic aortic aneurysm with a Dacron interposition graft. Esophagoscopy 2 months after the aneurysm repair demonstrated a large mid-esophageal erosion with visualization of the aortic graft at the base. The aortoesophageal fistula had been clinically silent to this point. During preparation for surgery the patient developed large-volume esophageal hemorrhage and died following attempted endovascular repair of the fistula. A review of the literature on the diagnosis and surgical management of aortoesophageal fistula is presented.Presented at the 30th Annual Meeting of the Military Society for Vascular Surgery, Bethesda, MD, December 5, 2002.  相似文献   
108.
Communication between the amygdala and other brain regions critically regulates sensitivity to threat, which has been associated with risk for mood and affective disorders. The extent to which these neural pathways are genetically determined or correlate with risk-related personality measures is not fully understood. Using functional magnetic resonance imaging, we evaluated independent and interactive effects of the 5-HTTLPR genotype and neuroticism on amygdala functional connectivity during an emotional faces paradigm in 76 healthy individuals. Functional connectivity between left amygdala and medial prefrontal cortex (mPFC) and between both amygdalae and a cluster including posterior cingulate cortex, precuneus and visual cortex was significantly increased in 5-HTTLPR S′ allele carriers relative to LALA individuals. Neuroticism was negatively correlated with functional connectivity between right amygdala and mPFC and visual cortex, and between both amygdalae and left lateral orbitofrontal (lOFC) and ventrolateral prefrontal cortex (vlPFC). Notably, 5-HTTLPR moderated the association between neuroticism and functional connectivity between both amygdalae and left lOFC/vlPFC, such that S′ carriers exhibited a more negative association relative to LALA individuals. These findings provide novel evidence for both independent and interactive effects of 5-HTTLPR genotype and neuroticism on amygdala communication, which may mediate effects on risk for mood and affective disorders.  相似文献   
109.
The effects of exogenous serotonin on pentagastrin-stimulated gastric acid secretion and antral motility were evaluated with regard to inhibition kinetics and receptor mediation. Conscious gastric fistula dogs were used. Serotonin inhibited the acid secretion dose-dependently, whereas the antral motility was initially stimulated and thereafter inhibited. The inhibition of secretion was counteracted by different beta-adrenergic blocking drugs and methysergide, whereas the inhibition of antral motility was blocked by methysergide and indomethacin. Dose-response analysis showed inhibition of non-competitive types. This study supports the concept of differences in the regulation of gastric acid secretion and motility, but further experiments with simultaneous registration are required.  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