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   1380篇
  免费   116篇
  国内免费   9篇
耳鼻咽喉   11篇
儿科学   75篇
妇产科学   18篇
基础医学   205篇
口腔科学   107篇
临床医学   125篇
内科学   272篇
皮肤病学   41篇
神经病学   103篇
特种医学   141篇
外科学   128篇
综合类   44篇
预防医学   68篇
眼科学   37篇
药学   65篇
中国医学   7篇
肿瘤学   58篇
  2023年   9篇
  2022年   20篇
  2021年   32篇
  2020年   24篇
  2019年   21篇
  2018年   52篇
  2017年   25篇
  2016年   37篇
  2015年   54篇
  2014年   52篇
  2013年   77篇
  2012年   86篇
  2011年   84篇
  2010年   83篇
  2009年   89篇
  2008年   55篇
  2007年   66篇
  2006年   39篇
  2005年   46篇
  2004年   33篇
  2003年   39篇
  2002年   28篇
  2001年   22篇
  2000年   18篇
  1999年   13篇
  1998年   43篇
  1997年   42篇
  1996年   43篇
  1995年   38篇
  1994年   23篇
  1993年   31篇
  1992年   9篇
  1991年   8篇
  1990年   6篇
  1989年   19篇
  1988年   16篇
  1987年   11篇
  1986年   15篇
  1985年   14篇
  1984年   12篇
  1983年   12篇
  1982年   5篇
  1981年   13篇
  1980年   7篇
  1979年   5篇
  1978年   6篇
  1977年   8篇
  1976年   9篇
  1975年   2篇
  1884年   1篇
排序方式: 共有1505条查询结果,搜索用时 15 毫秒
71.

INTRODUCTION

Solid pseudopapillary neoplasm (SPPN) was first characterized by Virginia Frantz in 1959. The duodenum-preserving pancreatic head resection (DPPHR) has been described as treatment for low-grade malignant tumors of the head of the pancreas including eight cases of SPPN.PRESENTATION OF CASE: A 16-year-old white female patient presented with abdominal pain and dyspepsia. Computed tomography scan of abdomen showed a 10 × 9 × 10 cm3 lesion on the pancreatic head. After radiological diagnosis of SPPN the patient was submitted to DPPHR. Resection was achieved with clear margins. Immunohistochemical study demonstrated positivity for progesterone receptor, β-catenin, cytoplasmic paranuclear dot-like CD99, negativity for chromogranin and S100 protein and Ki 67 index of 1%.

DISCUSSION

A large encapsulated pancreatic mass with well-defined borders that contains areas of calcifications and intratumoral hemorrhage on CT scan in a young female is virtually diagnostic of an SPPN. A particular dot-like intracytoplasmic expression of CD99 appears to be highly unique for SPPN

CONCLUSION

DPPHR should be considered in cases of SPPN in the pancreas head if there is no compromise with oncologic radicality.  相似文献   
72.
Epilepsy is associated with an extended spectrum of behaviour, psychiatric problems, and learning difficulties. The aim of this study was to establish the natural history of children with first unprovoked seizures. We studied prospectively 200 children under the age of 11 years who attended hospital emergency with a first unprovoked seizure. Demographic variables, personal and family history, neurological examination, EEG, psychiatric, and cognitive and educational profiles were analysed. Patients who developed epilepsy were characterised with respect to: time to relapse, remission rate, duration of epilepsy, neuroimaging, aetiology, epileptic syndrome, and therapeutic regimen. These results were compared to data of patients who had a single seizure over a follow‐up period of 15 years. Thirty percent of children who had a first unprovoked seizure developed epilepsy. Partial seizure type was a statistically significant variable for the development of epilepsy. An EEG with epileptic abnormalities proved to be the main risk factor for recurrence. Fifteen years later, the group with epilepsy exhibited a 2.6 greater risk of psychiatric and academic comorbidities, compared to the group without epilepsy.  相似文献   
73.

Background

In the Netherlands, screening for chlamydia (the most prevalent sexually transmitted infection worldwide) is a relatively simple and free procedure. Via an invitation letter sent by the public health services (PHS), people are asked to visit a website to request a test kit. They can then do a chlamydia test at home, send it anonymously to a laboratory, and, within two weeks, they can review their test results online and be treated by their general practitioner or the PHS. Unfortunately, the participation rates are low and the process is believed to be not (cost-) effective.

Objective

The objective of this study was to assess whether the low participation rate of screening for chlamydia at home, via an invitation letter asking to visit a website and request a test kit, could be improved by optimizing the invitation letter through systematically applied behavior change theories and evidence.

Methods

The original letter and a revised letter were randomly sent out to 13,551 citizens, 16 to 29 years old, in a Dutch municipality. Using behavior change theories, the revised letter sought to increase motivation to conduct chlamydia screening tests. The revised letter was tailored to beliefs that were found in earlier studies: risk perception, advantages and disadvantages (attitude), moral norm, social influence, and response- and self-efficacy. Revisions to the new letter also sought to avoid possible unwanted resistance caused when people feel pressured, and included prompts to trigger the desired behavior.

Results

No significant differences in test package requests were found between the two letters. There were also no differences between the original and revised letters in the rates of returned tests (11.80%, 581/4922 vs 11.07%, 549/4961) or positive test results (4.8%, 23/484 vs 4.1%, 19/460). It is evident that the new letter did not improve participation compared to the original letter.

Conclusions

It is clear that the approach of inviting the target population through a letter does not lead to higher participation rates for chlamydia screening. Other approaches have to be developed and pilot tested.  相似文献   
74.
75.
76.
由于治疗方法的进步,近80%的儿童和青少年癌症患者能够长期生存。在美国,约有270000例儿童癌症的幸存者,即每640名20至39岁成年人中就有一名幸存者。大量的幸存者有利于儿童癌症治疗后长期健康结果的研究。现在可以明确的是,化疗和放疗所致的儿童各器官系统损害在临床上可能潜伏多年。为了全面了解治疗儿童癌症而继发的健康问题,重要的是衡量三项长期结果:健康状况、死亡率和患病率。这三项中,关于前两项已有相当好的研究报道。在一项对20227例癌症5年生存者的回顾性分析中,Mertens等发现以下原因导致的超额死亡率具有统计学意义:继发癌症(…  相似文献   
77.
目的探讨高脂血症性急性胰腺炎(HAP)和非高脂血症性急性胰腺炎的特点及临床救治效果。方法回顾分析我院在2013年1月至2013年12月收治的99例急性胰腺炎的临床资料,根据患者有无高脂血症将其分为HAP组(高脂血症患者)和对照组(无高脂血症的AP患者);患者均接受标准化临床治疗,比较2组患者病情、血浆生化指标、治疗转归、住院时间与费用、复发等情况。结果 HAP组重度胰腺炎比例(13.6%)明显高于对照组(7.8%),HAP组血糖和尿酸均显著高于对照组,其中HAP组血糖平均值达到对照组的171%,而HAP组的血淀粉酶却仅为对照组的44.5%;HAP组1年内的复发率(13.6%)显著高对于照组(2.6%),P0.01差异有统计学意义。结论高血脂对急性胰腺炎的病情、表现和治疗结果均有明显影响,应引起高度重视。  相似文献   
78.
This study evaluated the stability of strawberry pulp subjected to three factors, pasteurisation (pasteurised and unpasteurised), freezing method (static air and forced air) and storage time (0, 2, 4 and 6 months). Pasteurisation favoured vitamin C retention during storage but enhanced the total loss of phenolics without affecting anthocyanin levels. Freezing by forced air was more effective in retaining phenolics during the first 4 months of storage, although the freezing method did not affect the anthocyanin levels. Processing and storage reduced the levels of individual phenolics. Freezing by forced air was more effective than static air in retaining antioxidant activity of the pulp. Polyphenol oxidase and peroxidase enzyme levels were relatively stable and independent of pasteurisation, freezing and storage time. Even after 6 months of frozen storage, strawberry pulp is a significant source of nutrients and bioactive compounds and retains high antioxidant capacity independent of pasteurisation and freezing method.  相似文献   
79.
80.
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