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   2588篇
  免费   186篇
  国内免费   9篇
耳鼻咽喉   74篇
儿科学   75篇
妇产科学   41篇
基础医学   314篇
口腔科学   60篇
临床医学   196篇
内科学   527篇
皮肤病学   116篇
神经病学   105篇
特种医学   155篇
外科学   476篇
综合类   63篇
预防医学   130篇
眼科学   97篇
药学   129篇
中国医学   11篇
肿瘤学   214篇
  2023年   23篇
  2022年   57篇
  2021年   118篇
  2020年   57篇
  2019年   62篇
  2018年   80篇
  2017年   60篇
  2016年   72篇
  2015年   54篇
  2014年   91篇
  2013年   125篇
  2012年   190篇
  2011年   182篇
  2010年   122篇
  2009年   76篇
  2008年   147篇
  2007年   163篇
  2006年   161篇
  2005年   161篇
  2004年   144篇
  2003年   98篇
  2002年   86篇
  2001年   48篇
  2000年   33篇
  1999年   19篇
  1998年   17篇
  1997年   9篇
  1996年   18篇
  1995年   19篇
  1994年   10篇
  1993年   10篇
  1992年   27篇
  1991年   23篇
  1990年   17篇
  1989年   23篇
  1988年   19篇
  1987年   13篇
  1986年   11篇
  1985年   18篇
  1984年   19篇
  1983年   13篇
  1982年   10篇
  1981年   5篇
  1980年   10篇
  1979年   13篇
  1978年   6篇
  1975年   4篇
  1974年   6篇
  1973年   5篇
  1970年   6篇
排序方式: 共有2783条查询结果,搜索用时 15 毫秒
101.
BackgroundThis study investigates in‐hospital mortality amongst patients with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and its relation to serum levels of gamma‐glutamyl transferase (GGT).MethodsPatients were stratified according to serum levels of gamma‐glutamyl transferase (GGT) (GGT<50 IU/L or GGT≥50 IU/L).ResultsA total of 802 participants were considered, amongst whom 486 had GGT<50 IU/L and a mean age of 48.1 (16.5) years, whilst 316 had GGT≥50 IU/L and a mean age of 53.8 (14.7) years. The chief sources of SARS‐CoV‐2 transmission were contact (366, 45.7%) and community (320, 40%). Most patients with GGT≥50 IU/L had either pneumonia (247, 78.2%) or acute respiratory distress syndrome (ARDS) (85, 26.9%), whilst those with GGT<50 IU/L had hypertension (141, 29%) or diabetes mellitus (DM) (147, 30.2%). Mortality was higher amongst patients with GGT≥50 IU/L (54, 17.1%) than amongst those with GGT<50 IU/L (29, 5.9%). More patients with GGT≥50 required high (83, 27.6%) or low (104, 34.6%) levels of oxygen, whereas most of those with GGT<50 had no requirement of oxygen (306, 71.2%). Multivariable logistic regression analysis indicated that GGT≥50 IU/L (odds ratio [OR]: 2.02, 95% confidence interval [CI]: 1.20–3.45, p=0.009), age (OR: 1.05, 95% CI: 1.03–1.07, p<0.001), hypertension (OR: 2.06, 95% CI: 1.19–3.63, p=0.011), methylprednisolone (OR: 2.96, 95% CI: 1.74–5.01, p<0.001) and fever (OR: 2.03, 95% CI: 1.15–3.68, p=0.016) were significant predictors of all‐cause cumulative mortality. A Cox proportional hazards regression model (B = −0.68, SE =0.24, HR =0.51, p = 0.004) showed that patients with GGT<50 IU/L had a 0.51‐times lower risk of all‐cause cumulative mortality than patients with GGT≥50 IU/L.ConclusionHigher levels of serum GGT were found to be an independent predictor of in‐hospital mortality.  相似文献   
102.
103.
104.

Background

There is no consensus as to the impact of lymph node micrometastases (LNMM) on survival of patients with gastric cancer. The aim of this analysis was to investigate the prognostic significance of LNMM in patients with histologic node-negative gastric cancer.

Methods

We searched relevant studies from PubMed, Embase, and the Cochrane Library (1966–2013.5), used software STATA 12.0 to pool the outcomes of each study. Mantel-Haenszel and Inverse Variance methods were used in a fixed effect model and a random effect model, respectively. The hazard ratios (HR) and odds risk (OR) at their 95% confidence intervals (CIs) were used as measures to investigate the prognostic importance of LNMM, by searching for a correlation between the clinical pathologic features and LNMM.

Results

Our analysis of 18 eligible studies revealed that patients with LNMM had an increased likelihood of having a worse 5-y survival rate (HR 2.81; 95% CI:1.96–4.02). Subgroup analyses showed a more significant result for patients in pT1-2N0 (HR 3.52; 95% CI 1.88–6.62). The analyses also revealed that (OR 1.32; 95% CI 1.17–1.48), lymphatic invasion (OR 2.21; 95% CI 1.42–3.44) and venous invasion (OR 1.41; 95% CI 1.08–1.85) were associated with the occurrence of LNMM.

Conclusions

There is a positive correlation between LNMM and an unfavorable surgical outcome in gastric cancer. Undifferentiated histologic findings, lymphatic invasion, and venous invasion are high risk factors for the occurrence of LNMM.  相似文献   
105.
Haemorrhagic complications of pancreaticoduodenectomy   总被引:6,自引:0,他引:6  
BACKGROUND: Haemorrhagic complication occurs in 5-16% of patients following pancreaticoduodenectomy (PD). We report an analysis of patients with post-PD bleed, to identify predictors of bleed, predictors of survival following bleed and the management of post-PD bleed. METHODS: Two hundred and eighteen patients with periampullary cancers underwent PD from 1989 to 2002. Forty-four (20.2%) patients had a bleeding complication. Of these, 25 patients had an intra-abdominal (IA) bleed and 21 had gastrointestinal (GI) bleed (two had both IA and GI bleed). Clinical, biochemical and tumour characteristics were analysed to identify factors influencing bleeding complications. RESULTS: The median time to presentation was 4.5 days (0-21 days). Serum bilirubin (P = 0.000, OR: 1.090) and pancreaticojejunostomy (PJ) leak (P = 0.009, OR: 3.174) were significant independent factors predicting bleeding complications. Forty-three per cent of patients each had early bleed (<48 h after PD) or delayed bleed (7 days after PD). Comparison of early and late bleeds showed that IA bleed (P = 0.02) presented as early bleeds. Male sex (P = 0.00) longer duration of jaundice (P = 0.02), PJ leak (P = 0.001), HJ leak (P = 0.001), duct to mucosa type of PJ anastomosis (P = 0.03) and IA abscess (P = 0.00) were associated with a significantly higher incidence of late bleeds. Overall mortality after PD was 9.6% with 34% and 3% in bleeders and non-bleeders, respectively. Septicaemia (P = 0.01, OR: 5.49), and acute renal failure (P = 0.01) were associated with increased mortality. CONCLUSIONS: Bleeding complications following PD were seen in one-fifth of patients and were associated with high mortality. Serum bilirubin levels and PJ leak were significant factors associated with bleeding complications. Septicaemia and acute renal failure were significant factors associated with mortality in the bleeders.  相似文献   
106.
Laparoscopic approach for treatment of colorectal malignancy is gaining acceptance gradually; however the benefits of laparoscopic surgery in colonic and rectal tumours is still open to debate. This study aims at a retrospective analysis of operative and short term outcome of patients with rectosigmoid tumours. A retrospective analysis of operative, postoperative and short-term outcome of 62 patients who underwent laparoscopic colorectal resection for cancer of rectosigmoid region were compared with a same number of parameters-matched patients who underwent open colorectal resection. Blood transfusion requirement was significantly more in the open group compared to the laparoscopy group (38.7% versus 6.4%, p = 0.001). ICU stay was less in the laparoscopy group (p = <0.05) and they were started on oral liquid diet earlier (p = 0.013). The number of the lymph nodes retrieved, positive distal margin and radial involvement were similar in both groups. The hospital stay was significantly shorter in laparoscopy group (8.4 versus 13.8 days, p < 0.05). Radical operation for rectosigmoid tumors is technically feasible with laparoscopic surgery. Laparoscopic approach is associated with less blood loss, transfusion and significantly less ICU stay. Laparoscopic group recovers early and needs less hospital stay  相似文献   
107.
Statins are an extensively used class of drugs, and myopathy is an uncommon, but well-described side effect of statin therapy. Inflammatory myopathies, including polymyositis, dermatomyositis, and necrotizing autoimmune myopathy, are even more rare, but debilitating, side effects of statin therapy that are characterized by the persistence of symptoms even after discontinuation of the drug. It is important to differentiate statin-associated inflammatory myopathies from other self-limited myopathies, as the disease often requires multiple immunosuppressive therapies. Drug interactions increase the risk of statin-associated toxic myopathy, but no risk factors for statin-associated inflammatory myopathies have been established. Here we describe the case of a man, age 59 years, who had been treated with a combination of atorvastatin and gemfibrozil for approximately 5 years and developed polymyositis after treatment with omeprazole for 7 months. Symptoms did not resolve after discontinuation of the atorvastatin, gemfibrozil, and omeprazole. The patient was treated with prednisone and methotrexate followed by intravenous immunoglobulin, which resulted in normalization of creatinine kinase levels and resolution of symptoms after 14 weeks. It is unclear if polymyositis was triggered by interaction of the statin with omeprazole and/or gemfibrozil, or if it developed secondary to long-term use of atorvastatin only.  相似文献   
108.
109.
110.
Background: An emerging endophenotype of schizophrenia is the reduction of both power and phase locking of the 40 Hz auditory steady state response (ASSR), and there have been a number of reports linking increased γ activity with positive psychotic symptoms. Schizophrenia and, more specifically, positive psychotic symptoms have been closely linked to increased dopamine (DA) neurophysiology. Therefore, we gave dexamphetamine to healthy participants to determine the effect that increased DA transmission would have on the ASSR. Methods: We administered 0.45 mg/kg of dexamphetamine orally in a double-blind placebo-controlled crossover study. Stimuli were 20 Hz and 40 Hz click trains presented in an auditory oddball-type stimulus format (probability of stimulus presentation: 0.2 for targets, 0.8 for nontargets). Results: We included 44 healthy volunteers (18 women) in the study. Dexamphetamine significantly increased the 40 Hz power for both target and nontarget ASSR stimuli. Dexamphetamine did not significantly affect the 40 Hz phase-locking factor (PLF) or the 20 Hz power and PLF. Whereas there were significant effects of selective attention on power and PLF for 20 and 40 Hz ASSR, there were no significant interactions between dexamphetamine and selective attention. Limitations: Dexamphetamine releases both noradrenaline and DA with equal potency. Further research with selective dopaminergic and noradrenergic agents will better characterize the effects of monoamines on γ activity. Conclusion: The results demonstrate a frequency-specific effect of dexamphetamine on the ASSR. This finding is consistent with previous research that has found an association between increased γ and positive symptoms of psychosis. However, this result also raises the possibility that previous 40 Hz ASSR findings in people with schizophrenia may be confounded by effects of antipsychotic medication. Possible neural mechanisms by which dexamphetamine specifically increases 40 Hz power are also discussed. Australian and New Zealand Clinical Trials Registry number: ACTRN12608000610336.  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