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   1406篇
  免费   122篇
  国内免费   22篇
耳鼻咽喉   5篇
儿科学   59篇
妇产科学   17篇
基础医学   168篇
口腔科学   52篇
临床医学   119篇
内科学   250篇
皮肤病学   34篇
神经病学   77篇
特种医学   280篇
外科学   96篇
综合类   43篇
一般理论   2篇
预防医学   153篇
眼科学   18篇
药学   79篇
中国医学   3篇
肿瘤学   95篇
  2019年   11篇
  2018年   17篇
  2017年   16篇
  2016年   16篇
  2015年   12篇
  2014年   24篇
  2013年   38篇
  2012年   36篇
  2011年   40篇
  2010年   44篇
  2009年   39篇
  2008年   57篇
  2007年   42篇
  2006年   45篇
  2005年   24篇
  2004年   32篇
  2003年   27篇
  2002年   26篇
  2001年   39篇
  2000年   31篇
  1999年   34篇
  1998年   42篇
  1997年   50篇
  1996年   50篇
  1995年   39篇
  1994年   26篇
  1993年   35篇
  1992年   35篇
  1991年   38篇
  1990年   25篇
  1989年   45篇
  1988年   36篇
  1987年   63篇
  1986年   40篇
  1985年   31篇
  1984年   25篇
  1983年   22篇
  1982年   26篇
  1981年   32篇
  1980年   22篇
  1979年   11篇
  1978年   14篇
  1977年   17篇
  1976年   32篇
  1975年   18篇
  1974年   7篇
  1973年   9篇
  1972年   11篇
  1971年   11篇
  1970年   8篇
排序方式: 共有1550条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
46.
47.
BACKGROUND & AIMS: Shwachman syndrome is an inherited condition with multisystemic abnormalities, including exocrine pancreatic dysfunction. The aim of this study was to evaluate the occurrence and progression of features in a large cohort of patients. METHODS: Clinical records of 25 patients with Shwachman syndrome were reviewed. RESULTS: Mean birth weight (2.92 +/- 0.51 kg) was at the 25th percentile. However, by 6 months of age, mean heights and weights were less than the 5th percentile. After 6 months of age, growth velocity was normal. Severe fat maldigestion due to pancreatic insufficiency was present in early life (fecal fat, 26% +/- 17% of fat intake; age, < 2 years). Serial assessment of exocrine pancreatic function showed persistent deficits of enzyme secretion, but 45% of patients showed moderate age-related improvements leading to pancreatic sufficiency. Neutropenia was the most common hematologic abnormality (88%), but leukopenia, thrombocytopenia, and anemia were also frequently encountered. Patients with hypoplasia of all three bone marrow cellular lines (n = 11) had the worst prognosis; 5 patients died, 2 of sepsis and 3 of acute myelogenous leukemia. Other findings included hepatomegaly and/or abnormal liver function test results and skeletal abnormalities. CONCLUSIONS: A wide and varied spectrum of phenotypic abnormalities among patients with Shwachman syndrome is described. Pancreatic acinar dysfunction is an invariable abnormality. Patients with severe bone marrow involvement may have a guarded prognosis. (Gastroenterology 1996 Dec;111(6):1593-602)  相似文献   
48.
INTRODUCTION: Nonsustained ventricular tachycardia (NSVT) is a frequent phenomenon in some patients with heart disease, but its association with sustained ventricular tachycardias (ventricular tachycardia [VT]/ventricular fibrillation [VF]) is still not clear. The aim of this study was to determine whether NSVT incidence was associated with sustained VT/VF in patients with an implantable cardioverter defibrillator (ICD). METHODS AND RESULTS: Retrospective data analysis was conducted in 923 ICD patients with a mean follow-up of 4 months. NSVT and sustained VT/VF were defined as device-detected tachycardias. The incidence rates of NSVT and sustained VT/VF as well as ICD therapies were determined as episodes per patient. The NSVT index was defined as the product of NSVT episodes/day times the mean number of beats per episode, i.e., total beats/day. The NSVT index peak was defined as the highest value on or prior to the day with sustained VT/VF episodes. Patients (n = 393) with NSVT experienced a higher incidence of sustained VT/VF (17.2 +/- 63.0 episodes/patient) and ICD therapies (15.2 +/- 61.4 episodes/patient) than patients (n = 530) without NSVT (sustained VT/VF: 0.5 +/- 6.6 and therapies: 0.5 +/- 5.6; P < 0.0001). Approximately 74% of NSVT index peaks occurred on the same day or <3 days prior to sustained VT/VF episodes. The index was higher for peaks < or =3 days prior to the day with sustained VT/VF (94.3 +/- 140.1 total beats/day) than for peaks >3 days prior to the day with sustained VT/VF (32.7 +/- 55.9 total beats/day; P < 0.0001). CONCLUSION: ICD patients with NSVT represent a population more likely to experience sustained VT/VF episodes with a temporal association between an NSVT surge and sustained VT/VF occurrence.  相似文献   
49.
Variations of Ki-67, p53, and Adnab-9 monoclonal antibody reactions in colonic adenomas may be associated with colonic cancer risk. We studied the predictive value of these markers for adverse behavior in severely dysplastic colorectal adenomas, such as an associated carcinoma, multiplicity of adenomas, and subsequent development of adenomas. For this purpose we compared the clinical, gross, and histologic characteristics of highly dysplastic index polyps in 42 patients with Ki 67, p53, and Adnab-9 immunostaining and other molecular markers. Polyps were removed endoscopically, and severely dysplastic polyps were stained immunohistochemically with Ki-67, Adnab-9, and p53 protein by the avidin biotin conjugate (ABC) technique. Quantitative DNA (QDNA) was analyzed by computer-assisted image analysis. Ki-67 immunohistochemistry showed reversal of normal distribution of nuclear staining from the normal basal position to the upper third of the colonic crypts. This abnormality of immunostaining in dysplastic adenomas was the earliest detected by the panel we used. A statistically significant correlation was seen between invasiveness of carcinoma in the index polyp and polyp size (P = 0.003), sessile morphology (P = 0.037), and villous or tubulovillous histology (P = 0.019). In the index adenoma, p53 positivity was correlated with multiplicity at initial examination (P = 0.053), villous histology (P = 0.053), invasiveness of carcinoma (P < 0.003), and recurrence of colorectal adenomas (P = 0.025). Although p53 positivity and aneuploidy were correlated with invasiveness of carcinoma in the index polyp (P = 0.025), Adnab-9 positivity was not. However, Adnab-9 positivity in the index polyp was associated with multiplicity of adenomas (P = 0.04) as well as recurrence of adenomas (P < 0.024). In conclusion, in addition to the morphologic and histologic markers already known, Ki-67, Adnab-9 antibody, and p53 protein may be prognostic indicators useful in follow-up of patients with severely dysplastic colorectal adenomas. Adnab-9 antibody may identify a field defect in above-average-risk adenoma-bearing patients.  相似文献   
50.
Between September 1985 and December 1987, 74 patients underwent attempted endoscopic biliary therapy using a combined percutaneous transhepatic and endoscopic transpapillary approach (combined procedure). All patients had had failed endoscopy-alone procedures and had contraindications to surgery. The indication was palliation of malignant biliary obstruction in 66 cases (41 common bile duct, 25 hilar), assistance with sphincterotomy for the removal of common bile duct stones in 6 cases, and management of benign biliary stenosis in 2 cases. The initial procedure was percutaneous transhepatic access to the biliary tree, which was successful in all but 1 case (99%). The bile duct was drained externally for an average of 3.4 days before the combined procedure. One patient died during this period from hemorrhage associated with liver puncture. Combined procedure was performed in 72 cases and was successful in 60 [53 malignant stricture (53/66 = 80%), five common duct stone (5/6 = 83%), two benign stricture (2/2 = 100%)]. Procedure-related morbidity and mortality, respectively, were 12.5% and 0% for benign disease and 36% and 3% for malignant disease. The total (initial endoscopy included) morbidity and 30-day mortality were 33% and 0%, respectively, for benign disease and 62% and 27% for malignant disease. Subsequently, stent change has been required on 16 occasions, with endoscopy-only successful in 13 (81%) and repeat combined procedure being required in three (19%). The combined procedure improves the ability of endoscopy to offer nonsurgical therapy to poor risk patients with both malignant and benign biliary disease but is associated with significant morbidity and disease-related mortality.  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