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   1499篇
  免费   71篇
  国内免费   8篇
耳鼻咽喉   26篇
儿科学   37篇
妇产科学   31篇
基础医学   144篇
口腔科学   29篇
临床医学   158篇
内科学   311篇
皮肤病学   17篇
神经病学   114篇
特种医学   102篇
外科学   294篇
综合类   15篇
预防医学   61篇
眼科学   41篇
药学   148篇
中国医学   6篇
肿瘤学   44篇
  2024年   3篇
  2023年   21篇
  2022年   71篇
  2021年   106篇
  2020年   38篇
  2019年   44篇
  2018年   64篇
  2017年   51篇
  2016年   41篇
  2015年   45篇
  2014年   68篇
  2013年   88篇
  2012年   97篇
  2011年   101篇
  2010年   61篇
  2009年   54篇
  2008年   65篇
  2007年   94篇
  2006年   115篇
  2005年   72篇
  2004年   76篇
  2003年   54篇
  2002年   72篇
  2001年   5篇
  2000年   15篇
  1999年   6篇
  1998年   11篇
  1997年   2篇
  1996年   2篇
  1995年   4篇
  1994年   3篇
  1993年   1篇
  1992年   2篇
  1991年   8篇
  1990年   3篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1977年   1篇
  1970年   1篇
  1969年   1篇
  1965年   1篇
  1960年   1篇
排序方式: 共有1578条查询结果,搜索用时 15 毫秒
51.
52.

Background

We sought to identify nontraditional risk factors coded in administrative claims data and evaluate their ability to improve prediction of long-term mortality in patients undergoing percutaneous mitral valve repair.

Methods

Patients undergoing transcatheter mitral valve repair using MitraClip implantation between September 28, 2010, and September 30, 2015 were identified among Medicare fee-for-service beneficiaries. We used nested Cox regression models to identify claims codes predictive of long-term mortality. Four groups of variables were introduced sequentially: cardiac and noncardiac risk factors, presentation characteristics, and nontraditional risk factors.

Results

A total of 3782 patients from 280 clinical sites received treatment with MitraClip over the study period. During the follow-up period, 1114 (29.5%) patients died with a median follow-up time period of 13.6 (9.6 to 17.3) months. The discrimination of a model to predict long-term mortality including only cardiac risk factors was 0.58 (0.55 to 0.60). Model discrimination improved with the addition of noncardiac risk factors (c = 0.63, 0.61 to 0.65; integrated discrimination improvement [IDI] = 0.038, P < 0.001), and with the subsequent addition of presentation characteristics (c = 0.67, 0.65 to 0.69; IDI = 0.033, P < 0.001 compared with the second model). Finally, the addition of nontraditional risk factors significantly improved model discrimination (c = 0.70, 0.68 to 0.72; IDI = 0.019, P < 0.001, compared with the third model).

Conclusions

Risk-prediction models, which include nontraditional risk factors as identified in claims data, can be used to predict long-term mortality risk more accurately in patients who have undergone MitraClip procedures.  相似文献   
53.
Many techniques are described for the ligation of a difficult cystic duct (CD). The aim of this study is to assess the effectiveness and safety of stapling of a difficult CD in acute cholecystitis using Endo-GIA. From January 2008 to June 2012, 1441 patients with cholelithiasis underwent laparoscopic cholecystectomy (LC) at the Department of General Surgery, Haydarpasa Numune Education and Research Hospital. Of these, 19 (0.62%) were identified as having a difficult CD and were ligated using an Endo-GIA stapler. All patients were successfully treated with a laparoscopic approach. The length of hospital stay was 3.4 days. There were umbilical wound infections in 4 patients (21%). The length of follow-up ranged from 1.0 to 50.4 months. In conclusion, Endo-GIA is a safe and easy treatment method for patients with a dilated and difficult CD. The cystic artery should be isolated and ligated if possible before firing the Endo-GIA stapler. If isolation and stapling are not possible, fibrin sealant can be applied to avoid bleeding. The vascular Endo-GIA can be applied in a large CD, but for acute cholecystitis with an edematous CD, the Endo-GIA roticulator 4.8 or 3.5 stapler is preferred.Key words: Cholecystectomy, Endo-GIA, Acute cholecystitis, StaplerAfter the introduction of laparoscopic cholecystectomy (LC) in 1987,1 LC replaced open cholecystectomy as the gold standard for the treatment of cholelithiasis in international guidelines.2 LC was initially considered to be contraindicated for acute gallbladder inflammation, but it is currently a common procedure for acute cholecystitis.Some of the difficult situations a surgeon is likely to face during the performance of a laparoscopic cholecystectomy include anatomic anomalies such as a sessile gallbladder or short cystic duct and pathologic entities such as an empyema, Mirizzi syndrome, or a frozen Calot''s triangle secondary to infection and fibrosis.3It is suggested that laparoscopic surgery should be carried out within 72 hours from the onset of the symptoms because after that time there are higher rates of conversion to open procedures, increased risks of complications, and longer operative times.46 The generally accepted procedure in patients whose symptoms started 72 hours before admission is to “cool down” the patient with appropriate medical therapy and to perform LC after a period of 6 to 12 weeks.7,8 This approach aims to avoid a potentially more difficult cholecystectomy during an emergency admission and to avoid the difficulties of access to an emergency room.9,10 However, more than 20% of patients may fail to respond to conservative treatment and require an urgent and rather more difficult cholecystectomy, and a further 25% of patients will require readmission with a severe acute complication of cholelithiasis while awaiting a cholecystectomy.11,12 The scar formation, distortion, and organized adhesions around the gallbladder occurring secondary to the chronic inflammation in Calot''s triangle make the dissection difficult. The cystic duct (CD) is sometimes edematous, fibrous, or enlarged owing to inflammation and adhesions in acute cholecystitis and may be difficult to manage. Several methods were proposed for ligating the CD, including titanium or absorbable endoclip, endoloop, tie, ultrasonic or bipolar sealer, and the Endo-GIA stapler (Covidien, Mansfield, Massachusetts).1319This study proposes an effective, safe, and easy procedure for the stapling of dilated or difficult CD using the Endo-GIA.  相似文献   
54.

Background

To investigate the protective effect of 2-aminoethyl diphenylborinate (2-APB) against ischemia–reperfusion (I/R) injury in the rat kidney by an experimental study.

Materials and methods

Thirty male Sprague-Dawley rats were randomly divided into the following three groups: (1) sham group, (2) I/R group, and (3) I/R + 2-APB group. Renal I/R injury was induced by clamping the left renal pedicle for 45 min after right nephrectomy, followed by 3 h of reperfusion. The therapeutic agent 2-APB was administered intravenously at a dose of 2 mg/kg 10 min before renal ischemia. Glutathione, superoxide dismutase, total antioxidant capacity, malondialdehyde, tumor necrosis factor α, interleukin 6, aspartate aminotransferase, alanine aminotransferase, and creatinine levels were measured from blood samples, and the rats were sacrificed subsequently. Tissue samples were scored histopathologically. Visualization of apoptotic cells was performed using the terminal deoxynucleotidyl transferase dUTP nick end labeling staining method.

Results

2-APB significantly reduced serum malondialdehyde, tumor necrosis factor α, interleukin 6, aspartate aminotransferase, alanine aminotransferase, and creatinine levels in the I/R injury group. However, glutathione, superoxide dismutase, and total antioxidant capacity levels increased significantly. Histopathologic scores were significantly better and the rate of apoptosis was lower in the 2-APB group.

Conclusions

2-APB reduces oxidative stress and damage caused by renal I/R injury. The results of this study demonstrate that 2-APB can be used as an effective agent against I/R injury in the kidney.  相似文献   
55.
56.

INTRODUCTION

Kaposi''s sarcoma (KS) is a rare angioproliferative disorder of the vascular endothelium. The development of KS requires Human Herpes Virus 8 (HHV-8) infection. An associated HIV infection is usually seen. Isolated scrotal KS has rarely been reported. In this article, we present a case of KS that primarily involved the scrotum in a HIV negative patient.

PRESENTATION OF CASE

A 71-year old male patient admitted to the outpatient department due to nodular lesions on the scrotum. The patient declared that these lesions were present for nearly 5 years. Past medical history revealed that he underwent left thoracotomy and upper lobectomy in 2006 for adenosquamous lung carcinoma. Then, he received a single cycle of adjuvant chemotherapy consisted of docetaxel and cisplatin. Physical examination revealed 3 black small nodules on the scrotum. The anti-HIV test was negative. All scrotal lesions were surgically excised. The pathological investigation revealed KS of the lymphangioma-like type.

DISCUSSION

The pathogenesis of KS has still not been clearly elucidated. However, it is known that all forms of KS are associated with HHV-8 infections. A defect in immune system was almost always necessary. Therefore, KS is usually associated with HIV infection. KS of the penis has been reported in HIV negative patients. Very few cases of scrotal KS have been presented. In a recent review, only 1 patient had scrotal KS out of 32 cases with HIV negative KS. In our case, the patient received a cycle of chemotherapy that might affect his immune system. The lymphangioma-like type is a common morphological sub-type. While lymph edemas are commonly observed in this sub-type, no edema in the lymphs was present in our case.

CONCLUSION

Classical KS is generally observed in the lower extremities, it can rarely affect scrotal skin as isolated lesions. Therefore, a careful physical examination should also include scrotum for these patients.  相似文献   
57.

INTRODUCTION

Atypical presentations of appendix have been reported including backache, left lower quadrant pain and groin pain from a strangulated femoral hernia containing the appendix. We report a case presenting an epigastric pain that was diagnosed after computed tomography as a perforated appendicitis on intestinal malrotation.

PRESENTATION OF CASE

A 27-year-old man was admitted with a three-day history of epigastric pain. Physical examination revealed tenderness and defense on palpation of epigastric region. There was a left subcostal incision with the history of diaphragmatic hernia repair when the patient was 3 days old. He had an intestinal malrotation with the cecum fixed at the epigastric region and the inflamed appendix extending beside the left lobe of liver.

DISCUSSION

While appendicitis is the most common abdominal disease requiring surgical intervention seen in the emergency room setting, intestinal malrotation is relatively uncommon. When patients with asymptomatic undiagnosed gastrointestinal malrotation clinically present with abdominal pain, accurate diagnosis and definitive therapy may be delayed, possibly increasing the risk of morbidity and mortality.

CONCLUSION

Atypical presentations of acute appendicitis should be kept in mind in patients with abdominal pain in emergency room especially in patients with previous childhood operation for diaphragmatic hernia.  相似文献   
58.
This study examined fathers' perceptions regarding their home-based activities (HBA) and the influence of fathers' demographic characteristics on their perceptions and practices at home. A total of 396 fathers completed a survey questionnaire describing their demographic information, perceptions and their practices regarding their involvement in HBA. Results indicated that fathers have moderate level of practice concerning their HBA, yet they have low perception of their actual practice at HBA. In addition, there was a statistical significance in HBA due to fathers' age, educational level and specialisation which had an influence on their perceptions as well. Recommendations and implications of future research were discussed.  相似文献   
59.
Eating disorders are serious threat to children and adolescents living in western countries. Parental influence as well as sociocultural standards, shapes specific attitudes towards selection, preparing and consuming food among juveniles. Orthorexia is a form of eating disorder, which is based on concentration over quality of consumed food. The paper provides symptomatology of orthorerxia along with various risk factors that may cause children and adolescents to develop disturbed eating behaviours.  相似文献   
60.
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