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   796篇
  免费   38篇
  国内免费   6篇
耳鼻咽喉   22篇
儿科学   81篇
妇产科学   38篇
基础医学   58篇
口腔科学   37篇
临床医学   49篇
内科学   176篇
皮肤病学   11篇
神经病学   88篇
特种医学   24篇
外科学   131篇
综合类   15篇
预防医学   18篇
眼科学   27篇
药学   32篇
肿瘤学   33篇
  2023年   5篇
  2022年   12篇
  2021年   17篇
  2020年   15篇
  2019年   18篇
  2018年   39篇
  2017年   18篇
  2016年   23篇
  2015年   31篇
  2014年   31篇
  2013年   46篇
  2012年   66篇
  2011年   66篇
  2010年   39篇
  2009年   39篇
  2008年   61篇
  2007年   67篇
  2006年   55篇
  2005年   47篇
  2004年   56篇
  2003年   34篇
  2002年   18篇
  2001年   15篇
  2000年   8篇
  1999年   6篇
  1998年   3篇
  1996年   1篇
  1993年   1篇
  1992年   2篇
  1984年   1篇
排序方式: 共有840条查询结果,搜索用时 15 毫秒
831.
GVHD is the most common and well-known cause of morbidity and mortality following allogeneic BM transplantation. The GVHD following OLT is an uncommon complication but has a high mortality and poses a major diagnostic and therapeutic challenge. We herein discussed a 12-month-old girl with multi-system LCH, who developed end-stage liver disease despite intensive chemotherapy. She underwent ABO-compatible liver transplantation at 28 months while in remission from LCH. The donor was her 26-yr-old father. Post-operative course was uneventful. The GVHD manifested with skin rash and BM suppression on post-transplant day 94 and confirmed by both microchimerism and skin biopsy. Prednisolone, basiliximab, and ATG were administered immediately but the bone marrow suppression was not improved and the patient died because of Candida sepsis at six-month post-transplant. GVHD after OLT should be keep in mind in patients with rash and BM suppression after liver transplantation. In LDLT, a patient who carries risk factors should investigated for optimal HLA matching.  相似文献   
832.
Study Type – Therapy (case control) Level of Evidence 2b

OBJECTIVE

? To determine whether men with varicoceles have lower testosterone levels than those without and to ascertain if testosterone levels increase after varicocelectomy.

PATIENTS AND METHODS

? We measured preoperative testosterone levels in 325 men with palpable varicoceles and in 510 men with vasectomy reversal without varicoceles who served as a comparison group. ? The testosterone levels between groups were compared by age. Of the men with varicoceles, 200 had data on both pre‐ and postoperative testosterone levels, which were compared to assess postoperative changes.

RESULTS

? Men with varicocele had significantly lower testosterone levels than the comparison group, with mean (sd ) levels of 416 (156) vs 469 (192) ng/dL (P < 0.001). This difference persisted when analysed by age. ? The testosterone levels significantly increased after repair from 358 (126) to 454 (168) ng/dL (P < 0.001). ? Of the 70% of patients with postoperative improvement in testosterone levels, the mean (sd ) increase in testosterone was 178 (142) ng/dL. The percentage change in testosterone levels was: 30% had no increase, 41% increased by ≤50%, 19% increased between by 51–100%, and 10% increased by >100%. ? There was no association between change in testosterone level and age, laterality of varicocele, or varicocele grade.

CONCLUSIONS

? Men with varicoceles had significantly lower testosterone levels than the comparison group of men with vasectomy reversal. ? Microsurgical varicocele ligation resulted in a significant increase in serum testosterone levels in more than two‐thirds of men. ? These findings suggest that varicocele is a significant risk factor for androgen deficiency and that repair may increase testosterone levels in men with varicocele and low testosterone levels.  相似文献   
833.
This study evaluated in vitro any changes in the morphology and mineral content of root canal dentin after treatments with Nd:YAG laser irradiation and 5 different irrigation solutions. The groups of extracted single-rooted human teeth were exposed to sterile saline solution, 5.25% NaOCl, 3% H2O2, 15% ethylenediaminetetraacetic acid, 2% chlorhexidine gluconate, and Nd:YAG laser irradiation. All prepared teeth were bisected longitudinally; half of each tooth was used for wavelength dispersive x-ray fluorescence spectrometry analysis to assess the mineral content. The other half was studied by using scanning electron microscopy to analyze the surface of the dentin. The results showed that the calcium level and calcium/phosphorus ratio decreased significantly with the NaOCl irrigation solutions (p < .05), suggesting the presence of changes at molecular level. Significant differences among the test groups were also observed in the scanning electron microscopy evaluation (p < .05). The lowest scores for root cleaning were obtained by using ethylenediaminetetraacetic acid followed by Nd:YAG laser treatment.  相似文献   
834.
Tay SK  Hirsch LJ  Leary L  Jette N  Wittman J  Akman CI 《Epilepsia》2006,47(9):1504-1509
BACKGROUND: Nonconvulsive status epilepticus (NCSE) is a highly heterogeneous clinical condition that is understudied in the pediatric population. OBJECTIVE: To analyze the epidemiological, clinical, and electroencephalograpic features in pediatric patients with NCSE. METHODS: We identified 19 pediatric patients with NCSE from the epilepsy database of the Comprehensive Epilepsy Center at, Columbia University between June 2000 and December 2003. Continuous electroencephalographic (EEG) monitoring was analyzed and chart review was performed. RESULTS: The patients ranged from 1 month old to 17 years of age. Five patients developed NCSE following convulsive status epilepticus (CSE), and a further 12 patients developed NCSE after brief convulsions. Two developed NCSE as the first manifestation during a comatose state following hypoxic events. Acute hypoxic-ischemic injury was the most frequent etiology of NCSE in our population (5 of 19; 26%), followed by exacerbation of underlying neurometabolic disease (4 of 19; 21%), acute infection (3 of 19; 16%), change in antiepileptic drug regimen (3 of 19;16%), refractory epilepsy (2 of 19; 11%) and intracranial hemorrhage (2 of 19; 11%). Six patients had associated periodic lateralized epileptiform discharges (PLEDs), one had generalized periodic epileptiform discharges (GPEDs). Five (5 of 19; 26%) patients died of the underlying acute medical illness. Periodic discharges were associated with worse outcome. CONCLUSION: The majority of our patients with NCSE had preceding seizures in the acute setting prior to the diagnosis of NCSE, though most of these seizures were brief, isolated convulsions (12 patients) rather than CSE (five patients). Prolonged EEG monitoring to exclude NCSE may be warranted in pediatric patients even after brief convulsive seizures. Prompt recognition and treatment may be necessary to improve neurological outcome.  相似文献   
835.
This study evaluated the two-year clinical performance of one microhybrid composite and three different types of flowable resin materials in non-carious cervical lesions. A total of 252 noncarious cervical lesions were restored in 37 patients (12 male, 25 female) with Admira Flow, Dyract Flow, Filtek Flow and Filtek Z250, according to manufacturers' instructions. All the restorations were placed by one operator, and two other examiners evaluated the restorations clinically within one week after placement and after 6, 12, 18 and 24 months, using modified USPHS criteria. At the end of 24 months, 172 restorations were evaluated in 26 patients, with a recall rate of 68%. Statistical analysis was completed using the Pearson Chi-square and Fisher-Freeman-Halton tests (p < 0.05). Additionally, survival rates were analyzed with the Kaplan-Meier estimator and the Log-Rank test (p < 0.05). The Log-Rank test indicated statistically significant differences between the survival rates of Dyract Flow/Admira Flow and Dyract Flow/Filtek Z250 (p < 0.05). While there was a statistically significant difference between Dyract Flow and the other materials for color match at 12 and 18 months, no significant difference was observed among all of the materials tested at 24 months. Significant differences were revealed between Filtek Z250 and the other materials for marginal adaptation at 18 and 24 months (p < 0.05). With respect to marginal discoloration, secondary caries, surface texture and anatomic form, no significant differences were found between the resin materials (p > 0.05). It was concluded that different types of resin materials demonstrated acceptable clinical performance in non-carious cervical lesions, except for the retention rates of the Dyract Flow restorations.  相似文献   
836.
Background Pyrrolidine dithiocarbamate (PDTC) is a low-molecular thiol antioxidant and potent inhibitor of nuclear factor-κB (NF-κB) activation. It has been shown to attenuate local harmful effects of ischemia/reperfusion (I/R) injury in many organs. In this study, we aimed to study the effect of PDTC on lung reperfusion injury induced by superior mesenteric occlusion. Methods Male Wistar-albino rats randomized into three groups: (1) sham-operated control group (n = 12), laparotomy without I/R injury; (2) intestinal ischemia/reperfusion (I/R) group (n = 12), 60 min of ischemia by superior mesenteric occlusion followed by 2 h of reperfusion; and (3) I/R+PDTC-treated group (n = 12), 100 mg/kg injection of PDTC intravenously, 30 min after the commencement of reperfusion. Evans blue dye was injected to half of rats in all groups before the induction of I/R. We assessed the degree of pulmonary tissue injury biochemically by measuring malondialdehyde (MDA), glutathione (GSH), and nitric oxide (NO) levels, and histopathologically by establishing pulmonary neutrophil sequestration and acute lung injury scoring. Pulmonary edema was evaluated by Evans blue dye extravasation, as well as lung tissue wet/dry weight ratios. Results Pyrrolidine dithiocarbamate treatment significantly reduced the MDA and NO levels, and increased the GSH levels in the lung parenchyma, biochemically (p < 0.05), and atteneuated the pulmonary parenchymal damage, histopathologically (p < 0.05). However, pulmonary neutrophil sequestration was not affected by postischemic treatment with PDTC (p > 0.05). Pyrrolidine dithiocarbamate administration also significantly alleviated the formation of pulmonary edema, as evidenced by the decreased Evans blue dye extravasation and organ wet/dry weight ratios (p < 0.05). Conclusions This study showed that postischemic treatment with PDTC significantly attenuated the lung reperfusion injury. Further clinical studies are needed for better understanding of the specific mechanisms of PDTC protection against I/R-related organ injury and to clarify whether PDTC may be a useful therapeutic agent during particular operations where remote organ I/R injury occurs.  相似文献   
837.
838.
839.
BACKGROUND: Previous studies have reported controversial results regarding the effectiveness of systemic thrombolysis in preventing left ventricular (LV) thrombus after acute myocardial infarction (MI). HYPOTHESIS: This study was performed to evaluate the influences of thrombolysis, and particularly successful reperfusion, on the incidence of LV thrombus formation after acute anterior MI. METHODS: In all, 191 patients suffering from a first attack of acute anterior MI were prospectively evaluated by two-dimensional echocardiography and coronary angiography, performed at the end of the first week and within the first two weeks of MI, respectively. Of these, 98 who presented within 12 h of onset of symptoms received intravenous streptokinase (1.5 million IU), while the remaining 93 patients who, either because of contraindications or late admission, did not receive thrombolytic treatment served as control group. All patients received aspirin and full-dose anticoagulation with intravenous heparin. Successful reperfusion in the streptokinase group was assessed by enzymatic and electrocardiographic evidence. RESULTS: The overall incidence of LV thrombi was 24.6% (47/191). When all patients were evaluated, no statistically significant difference was found between the frequency of LV thrombi in the patients who had thrombolysis (22.4%) and those who did not (26.8%), despite a trend toward the formation of fewer thrombi in the initial group (p > 0.05). However, the patients who had successful reperfusion with streptokinase (n = 64) had significantly reduced incidence of LV thrombi compared with those who did not receive thrombolytic therapy (20 vs. 26.8%, p < 0.05). Stepwise multivariate analysis suggested that LV abnormal wall motion score (p = 0.01) and presence of LV aneurysm were independent predictors of LV thrombus formation in patients with acute anterior MI. CONCLUSION: Not all patients who received streptokinase for acute anterior MI, but only those with successful reperfusion had reduced incidence of LV thrombi. The favorable effects of thrombolysis on LV thrombus formation are probably due to the preservation of global LV systolic function.  相似文献   
840.
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