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   662篇
  免费   26篇
  国内免费   4篇
耳鼻咽喉   5篇
儿科学   61篇
妇产科学   12篇
基础医学   59篇
口腔科学   22篇
临床医学   41篇
内科学   134篇
皮肤病学   5篇
神经病学   46篇
特种医学   43篇
外科学   198篇
综合类   5篇
预防医学   6篇
眼科学   20篇
药学   16篇
中国医学   1篇
肿瘤学   18篇
  2023年   4篇
  2022年   5篇
  2021年   12篇
  2020年   8篇
  2019年   11篇
  2018年   25篇
  2017年   20篇
  2016年   25篇
  2015年   23篇
  2014年   23篇
  2013年   44篇
  2012年   48篇
  2011年   41篇
  2010年   24篇
  2009年   20篇
  2008年   52篇
  2007年   58篇
  2006年   52篇
  2005年   54篇
  2004年   39篇
  2003年   33篇
  2002年   37篇
  2001年   8篇
  2000年   2篇
  1999年   5篇
  1998年   3篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1991年   2篇
  1989年   2篇
  1987年   1篇
  1985年   2篇
  1983年   1篇
  1978年   1篇
  1976年   1篇
排序方式: 共有692条查询结果,搜索用时 15 毫秒
611.
BACKGROUND: In this study, we endeavored to determine whether the incidence of cholelithiasis (CL) was increased in chronic renal failure (CRF) patients with secondary hyperparathyroidism on a peritoneal dialysis (PD) program. We also evaluated the factors that might have some influence on the development of CL. METHODS: A total of 59 CRF patients undergoing PD were included in the study. We studied the following groups to determine whether parathyroid hormone (PTH) levels were increased in CRF-PD patients: twenty patients with secondary hyperparathyroidism (group 1) and 39 patients with normal PTH levels (group 2). PTH levels were maintained at three times the upper limit of normal. Biochemical parameters were obtained for each CRF-PD patient. All patients underwent abdominal ultrasonography to screen for the presence of cholelithiasis. For statistical analysis, chi2, t test, and logistic regression analysis were used; p < 0.05 was considered as significant. RESULTS: We found an almost ten times higher incidence (25% vs. 2.6%) of CL in group 1 patients with statistical significance (p = 0.007). When the incidence of CL according to sex, creatinine, and PTH levels were considered, female gender, creatinine, and PTH levels were higher in group 1, which was also significant statistically. No significant relationship was detected between gallbladder stone formation and the other analyzed biochemical parameters. CONCLUSIONS: We found that the incidence of CL in CRF-PD patients with secondary hyperparathyroidism was higher than CRF-PD patients with normal PTH levels. It was also detected that female gender, high creatinine levels, and elevated PTH levels might influence the development of CL in CRF-PD patients.  相似文献   
612.
Here, we present a patient who underwent transperitoneal laparoscopic nephrectomy for a nonfunctional kidney on the left side, and who was found to have xanthogranulomatous pyelonephritis (XGP) on the subsequent histopathology examination. XGP is a severe, chronic infection of the renal parenchyma. Nephrectomy is the treatment of choice. Preoperative diagnosis of XGP can be challenging because the clinical presentation may vary. Our patient's loss of kidney function was due to a simple cortical kidney cyst that compressed the urinary collecting system. He presented only with mild flank pain and a poorly functioning kidney, and therefore XGP was not suspected before surgery. Because of the renal and perirenal inflammatory changes that commonly accompany XGP, the laparoscopic approach is difficult and is therefore rarely used. However, laparoscopic nephrectomy for XGP offers an easier recovery for the patient and therefore deserves further consideration as a method of treatment.  相似文献   
613.
BACKGROUND: Anterior cervical microdiscectomy (ACD) is commonly applied in the surgical treatment of cervical disc herniation. However, following discectomy procedure to perform a fusion process is still controversial. Therefore, a controlled, multicentric, prospective, randomized study was designed. MATERIAL AND METHOD: Totally 20 patients were operated. Eleven patients were operated with applying simple anterior microdiscectomy technique. Nine patients were operated via ACD and fusion with a semirigid plate technique. Preoperative and postoperative [immediate; postoperative first day and postoperative 1 y (mean 13.95 mo)] computed tomography studies and plain x-rays were obtained. The cervical disc and bilateral neural foramen heights of the operated level and adjacent segments were calculated. Pain assessment was performed using visual analog pain scale. Mann-Whitney statistical analysis method was applied to compare the outcomes for both groups. RESULTS: Satisfactory result was achieved in both groups. The pain scores for major complaint (arm pain) were decreased significantly in all patients after surgery regardless of the type of technique applied. The improvement in neck pain scores was significant only in patients who were treated with fusion procedure. There were no significant changes in disc height and neural foramen height measurements for both groups in adjacent levels in immediate and 1-year postoperative periods. The patients who were operated with simple ACD technique showed no significant decrease at postoperative first day in disc height and neural foramen height. However, the 1-year postoperative radiologic studies showed a significant decrease in disc height and neural foramen dimensions compared with preoperative values. The patients who were treated with fusion process showed a significant increase in disc height and nonsignificant increase in neural foramen heights at immediate postoperative study. However, with time, all dimensions showed significant decrease compared with preoperative values. CONCLUSIONS: ACD technique offers satisfactory outcome regardless of whether fusion process is applied or not. Fusion with semirigid plate offers an advantage at operated level in immediate postoperative period in regard of disc height and neural foramen height. However, semirigid anterior plates by definition do not stop subsidence and the advantage that is offered by this technique is not persistent. On the other hand, to apply fusion process with semirigid plate system offers significantly less narrowing in disc height compared with simple ACD technique.  相似文献   
614.
Introduction The effects of squamous and/or glandular differentiation in urothelial carcinoma of bladder on recurrence, progression and survival rate were evaluated in this study. Patients and methods Between 1998 and 2003, a total of 223 patients who had been treated with transurethral resection for bladder cancers were evaluated. The patients were divided into two groups as; Group I: tumor patients with squamous and/or glandular differentiation, Group II: patients without these findings. Results Histologically 189 (84.7%) were conventional urothelial carcinoma and 34 (15.2%) were tumors with squamous and/or glandular differentiation. The mean age of the patients was 64.4 ± 12.7 (range 36–81) years. Survival rates within a period of 46.23 ± 14.8 (12–67) months were 76.47% for Group I and 89.94% for Group II (P = 0.027). The stage distribution as pTa, pT1, and ≥pT2 was 2 (5.9%), 18 (52.9%), and 14 (41.2%) in Group I and 101 (53.4%), 51 (27%) and 37 (19.6%) in group II, respectively (P = 0.001). There was a statistically significant tendency towards higher stage at presentation in Group I and the grade distribution was significantly higher in Group I than Group II (P < 0.001). Conclusion High recurrence rates and poor prognosis of these patients should be kept in mind in the follow-up period. In this respect, these patients should be followed up closely.  相似文献   
615.
Septic shock has a high mortality rate due to the hypotension and circulatory disorder that occurs during its pathogenesis. Recently, humoral factors such as cytokines and nitric oxide became important in the complex pathophysiology of septic shock because there is a close relationship between the determined levels of these humoral factors and the responses to the therapy and survival periods. Verapamil and nifedipine are calcium channel blockers commonly used in the pharmacotherapy of cardiovascular disorders. In the present study these drugs were investigated in the rat septic shock model. In vivo hemodynamic parameters were recorded using a data acquisition system in endotoxin-induced septic shock in rats. The animals were followed for 5 h and blood pressure, rectal temperature, and ECG were recorded. Blood samples were collected at 1 h and 5 h time points after the injection of endotoxin, and serological samples were stored at −25°C. Subsequently, tumor necrosis factor-α, interleukin-10 (enzyme-linked immunosorbent assay), and nitrite (Griess reagent) were determined in these serological samples. Significant correlations were observed between these humoral factors and the disordered hemodynamic factors. A reversal of changes was observed in the levels of serum cytokines, nitrite levels, and hemodynamic parameters with verapamil and nifedipine preadministration (P < 0.05). Additionally, superoxide dismutase (SOD), catalase, and malondialdehyde (MDA) were determined in livers obtained from these animals at the end of the experiments, and these results were compared to hemodynamic parameters and cytokines. Nifedipine and verapamil increased the levels of MDA and SOD but did not change catalase activity.  相似文献   
616.

Background  

In patients with Roux-en-Y hepaticojejunostomy (HJ), endoscopic retrograde cholangiography (ERC) cannot usually be achieved since the anastomosis is not reachable via standard duodenoscope. In this study, we report our experience with ERC using double balloon enteroscope (DBE) (DBE-ERC) in patients with HJ.  相似文献   
617.
618.
Allergic diseases represent a complex innate and adoptive immune response to natural environmental allergens with Th2-type T cells and allergen-specific IgE predominance. Allergen-specific immunotherapy is the most effective therapeutic approach for disregulated immune response towards allergens by enhancing immune tolerance mechanisms. The main aim of immunotherapy is the generation of allergen nonresponsive or tolerant T cells in sensitized patients and downregulation of predominant T cell- and IgE-mediated immune responses. During allergen-specific immunotherapy, T regulatory cells are generated, which secrete IL-10 and induce allergen-specific B cells for the production of IgG4 antibodies. These mechanisms induce tolerance to antigens that reduces allergic symptoms. Although current knowledge highlights the role of T regulatory cell-mediated immunetolerance, definite mechanisms that lead to a successful clinical outcomes of allergen-specific immunotherapy still remains an open area of research.  相似文献   
619.
Introduction To investigate the contribution of perfusion-weighted MRI to the differentiation of meningiomas with atypical conventional MRI findings from intraaxial tumors.Methods We retrospectively analyzed 54 meningiomas, 12 glioblastomas and 13 solitary metastases. We detected 6 meningiomas with atypical features on conventional MRI resembling intraaxial tumors. The regional cerebral blood flow (rCBV) ratios of all tumors were calculated via perfusion-weighted MRI. The signal intensity-time curves were plotted and three different curve patterns were observed. The type 1 curve resembled normal brain parenchyma or the postenhancement part was minimally below the baseline, the type 2 curve was similar to the type 1 curve but with the postenhancement part above the baseline, and the type 3 curve had the postenhancement part below the baseline accompanied by widening of the curve. Student’s t-test was used for statistical analysis.Results On CBV images meningiomas were hypervascular and the mean rCBV ratio was 10.58±2.00. For glioblastomas and metastatic lesions, the rCBV ratios were 5.02±1.40 and 4.68±1.54, respectively. There was a statistically significant difference in rCBV ratios between meningiomas and glioblastomas and metastases (P<0.001). Only one of the meningiomas displayed a type 2 curve while five showed a type 3 curve. Glioblastomas and metastases displayed either a type 1 or a type 2 curve. None of the meningiomas showed a type 1 curve and none of the glioblastomas or metastases showed a type 3 curve.Conclusion Differentiating meningiomas with atypical conventional MRI findings from malignant intraaxial tumors can be difficult. Calculation of rCBV ratios and construction of signal intensity-time curves may contribute to the differentiation of meningiomas from intraaxial tumors.  相似文献   
620.
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