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   10501篇
  免费   1089篇
  国内免费   15篇
耳鼻咽喉   111篇
儿科学   281篇
妇产科学   300篇
基础医学   1479篇
口腔科学   302篇
临床医学   1327篇
内科学   2046篇
皮肤病学   120篇
神经病学   972篇
特种医学   274篇
外国民族医学   3篇
外科学   1305篇
综合类   187篇
一般理论   13篇
预防医学   1276篇
眼科学   116篇
药学   821篇
中国医学   5篇
肿瘤学   667篇
  2022年   81篇
  2021年   138篇
  2020年   114篇
  2019年   168篇
  2018年   180篇
  2017年   136篇
  2016年   136篇
  2015年   187篇
  2014年   260篇
  2013年   338篇
  2012年   526篇
  2011年   586篇
  2010年   286篇
  2009年   301篇
  2008年   480篇
  2007年   489篇
  2006年   486篇
  2005年   489篇
  2004年   445篇
  2003年   414篇
  2002年   414篇
  2001年   361篇
  2000年   330篇
  1999年   268篇
  1998年   107篇
  1997年   110篇
  1996年   92篇
  1995年   113篇
  1994年   95篇
  1993年   88篇
  1992年   214篇
  1991年   219篇
  1990年   216篇
  1989年   189篇
  1988年   180篇
  1987年   179篇
  1986年   196篇
  1985年   193篇
  1984年   138篇
  1983年   123篇
  1982年   79篇
  1981年   79篇
  1979年   135篇
  1978年   117篇
  1977年   92篇
  1976年   85篇
  1975年   70篇
  1974年   87篇
  1973年   93篇
  1972年   78篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Carcinoma of the papilla of Vater is classified as periampullary cancer representing 5% of all gastrointestinal tract malignancies. Early and accurate diagnosis is important for those patients with a tumor of the papilla, as the prognosis is more favorable than in other periampullary neoplasms. Endoscopically obtained biopsies from suspicious papillae can detect an early tumor, although even for skilled pathologists it is often difficult to differentiate carcinomas from noninvasive lesions on the basis of forceps biopsies. The purpose of this study was to assess the preoperative diagnostic accuracy of duodenoscopy appearance and biopsy in all cases with suspicion of tumor. Thirty patients with suspicion of carcinoma of the papilla of Vater and with final diagnosis established by pancreatoduodenectomy were included in this retrospective study. In each case, a comparison was made between endoscopic biopsy and duodenoscopic appearance. Duodenoscopic appearance sensitivity and accuracy for malignancy were 86% and 83%, respectively, whereas endoscopic biopsy sensitivity and accuracy were 65% and 67%, respectively. Although preoperative diagnosis of carcinoma of the papilla of Vater is useful for making therapeutic decisions, the diagnostic value of the endoscopic appearance was superior to endoscopic biopsy in this series. Presented at the 2003 American Hepato-Pancreato-Biliary Association Congress, Miami, Florida, February 27-March 3, 2003. Supported by FADA-CAPES/PROP 200J (M.L.D.).  相似文献   
42.
Frantz's tumour (papillary and cystic tumour) of the pancreas is a rare neoplasm usually seen in young women. It is of low grade malignancy and deserves special note among pancreatic malignancies as it is frequently amenable to local resection and has a good long-term survival rate after excision. Three such cases have been treated at Westmead Hospital, one young male and two females. In two the disease was confined to the pancreas. In one, local invasion outside the pancreas and trans-coelomic spread to the ovaries was present at the time of diagnosis. Complete surgical removal of macroscopic disease was achieved in all three and all remain disease free between 2 and 4 years post-surgery. All have good exocrine and endocrine pancreatic function. These cases are discussed in detail. The need to be aware of this uncommon variant of pancreatic cancer is stressed. Investigation and treatment options are reviewed. The role of cytology studies in diagnosis and the potential for long-term surgical control of this tumour are highlighted on the basis of our limited experience and that presented in recent surgical literature.  相似文献   
43.
The clinical presentation of SARS is nonspecific and diagnostic tests do not provide accurate results early in the disease course. Initial diagnosis remains reliant on clinical assessment. To identify features of the clinical assessment that are useful in SARS diagnosis, the exposure status and the prevalence and timing of symptoms, signs, laboratory and radiographic findings were determined for all adult patients admitted with suspected SARS during the Toronto SARS outbreak. Findings were compared between patients with laboratory-confirmed SARS and those in whom SARS was excluded by laboratory or public health investigation. Of 364 cases, 273 (75%) had confirmed SARS, 30 (8%) were excluded, and 61 (17%) remained indeterminate. Among confirmed cases, exposure occurred in the healthcare environment (80%) or in the households of affected patients (17%); community or travel-related cases were rare (<3%). Fever occurred in 97% of patients by the time of admission. Respiratory findings including cough, dyspnea and pulmonary infiltrates evolved later and were present in only 59, 37 and 68% of patients, respectively, at admission. Direct exposure, fever on the first day of illness, and elevated temperature, pulmonary infiltrates, lymphopenia and thrombocytopenia at admission were associated with confirmed cases. Rhinorrhea, sore throat, and an elevated neutrophil count at admission were associated with excluded cases. In the absence of fever or significant exposure, SARS is unlikely. Other clinical, laboratory and radiographic findings further raise or lower the likelihood of SARS and provide a rational basis for estimating the likelihood of SARS and directing initial management.  相似文献   
44.
45.
Phase I trial of piroxicam in 62 dogs bearing naturally occurring tumors   总被引:3,自引:0,他引:3  
Summary Piroxicam, a nonsteroidal antiinflammatory drug, was given to 62 dogs bearing naturally occurring tumors in a phase I clinical trial. Dose escalation was performed, with oral doses ranging from 0.5 mg/kg every 48 h (q48h) to 1.5 mg/kg q48h being tested. Dose-limiting gastromestinal irritation/ulceration occurred in all four animals that received 1.5 mg/kg q48h. The maximum tolerated dose was 1 mg/kg q48h. Subclinical renal papillary necrosis occurred in two dogs (initial dosages, 1 and 1.5 mg/kg q48h, respectively). Following dose escalation, an additional group of dogs was treated with 0.3 mg/kg piroxicam q24h per os, the accepted canine dosage prior to this trial. Inclusion of this treatment group enabled evaluation of the toxicity of and tumor response to a daily dosage regimen. No complete remissions occurred in this trial. Partial remission was documented in three of ten dogs exhibiting transitional-cell carcinoma, in three of five animals bearing squamous-cell carcinoma, in one of three dogs displaying mammary adenocarcinoma, and in the one dog that exhibited a transmissible venereal tumor. The results of this study support the additional evaluation of piroxicam in a phase II clinical trial in dogs bearing naturally occurring tumors.This investigation was supported by Pfizer Inc.  相似文献   
46.
OBJECTIVE: To determine to what degree attending physicians contribute to cost variations in the care of ventilator-dependent newborns. DATA SOURCES: Clinical data were merged with hospital financial data describing daily ancillary care costs during the first two weeks of life for 132 extremely low-birthweight newborns. In addition, each patient's chart was reviewed and illness severity graded using both SNAP and CRIB scores. STUDY DESIGN: This was a retrospective cohort of infants with birth weights of less than 1,001 grams and respiratory distress syndrome requiring mechanical ventilation in the first day of life. From birth up to two weeks of life, each received care directed by only one of 11 faculty neonatologists in a single university hospital. Data were analyzed stratified by these physicians. t-Test, ANOVA, and chi-square were used to assess bivariate data. For continuous data, log linear regressions were used. PRINCIPAL FINDINGS: After controlling for illness severity, when stratified by physicians, there were significant variances in the costs of ancillary resources for the study infants (p < .0001). Twenty-nine percent of the variance was attributable to whether or not the hospital day included the use of a ventilator. Physician identity explained only 5.6 percent (p < .0001). CONCLUSIONS: Physician identity was significant but explained less than 6 percent of the total variance in ancillary costs. Whether or not a ventilator was used during care was far more important. We conclude that for very sick babies during the first two weeks of care, reducing variations in ancillary services utilization among neonatologists will yield only modest savings.  相似文献   
47.
Diarrhea has been reported as an early, mild, and uncommon complication of carbamazepine (CBZ) therapy. We report three cases of intractable diarrhea induced by CBZ necessitating discontinuation of the drug.  相似文献   
48.
49.
Expression of the immediate early gene zif/268 (also termed NGFI-A, Krox 24, TIS8 and Egr-1) was investigated in awake rats following various long-term potentiation (LTP) induction protocols.zif/268 mRNA (Northern blots) and protein (immunohistochemistry) levels sharply increased following LTP, and followed a time course characteristic of other immediate early genes. When measured across 3 tetanization protocols known to produce differing degrees of LTP persistence,zif/268 induction was found to be more highly correlated with LTP duration than with the magnitude of initial LTP. These data support the hypothesis that the immediate early gene zif/268 plays a role as a third messenger in the cascade of cellular and nuclear events that govern the persistence of LTP.  相似文献   
50.
Anterior vertical fusion of the tracheal cartilages with normal pars membranacea is a rarely described tracheal anomaly. We report four cases of this anomaly, three associated with craniosynostosis syndromes and one with Goldenhar's syndrome. The anomaly was documented at postmortem examination in one case, both endoscopically and at tracheotomy in two cases, and endoscopically in one case. Documentation from gross postmortem photographs, photomicrographs, and intraoperative endoscopic photographs is presented so that the anatomical aspects of this anomaly can be thoroughly understood and recognized. All four newborn patients developed recurrent lower respiratory tract infections, reactive airway disease, and chronically retained secretions attributable to this anomaly. Neither tracheal stenosis nor stridor was encountered. In the three surviving patients, the infections grew less frequent and less severe in later childhood. These observations suggest that this tracheobronchial anomaly may be associated with a variety of craniofacial syndromes and may alter airflow dynamics in a way that predisposes to retained secretions and chronic pulmonary disease.  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