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   14373篇
  免费   694篇
  国内免费   82篇
耳鼻咽喉   109篇
儿科学   221篇
妇产科学   212篇
基础医学   1775篇
口腔科学   296篇
临床医学   789篇
内科学   3782篇
皮肤病学   122篇
神经病学   1173篇
特种医学   524篇
外科学   2751篇
综合类   39篇
一般理论   1篇
预防医学   475篇
眼科学   450篇
药学   934篇
中国医学   48篇
肿瘤学   1448篇
  2023年   83篇
  2022年   143篇
  2021年   217篇
  2020年   149篇
  2019年   227篇
  2018年   256篇
  2017年   215篇
  2016年   277篇
  2015年   231篇
  2014年   336篇
  2013年   465篇
  2012年   700篇
  2011年   801篇
  2010年   419篇
  2009年   399篇
  2008年   673篇
  2007年   760篇
  2006年   742篇
  2005年   889篇
  2004年   807篇
  2003年   855篇
  2002年   831篇
  2001年   360篇
  2000年   381篇
  1999年   343篇
  1998年   228篇
  1997年   170篇
  1996年   161篇
  1995年   138篇
  1994年   148篇
  1993年   134篇
  1992年   266篇
  1991年   226篇
  1990年   225篇
  1989年   210篇
  1988年   215篇
  1987年   198篇
  1986年   188篇
  1985年   172篇
  1984年   133篇
  1983年   85篇
  1982年   56篇
  1981年   41篇
  1980年   48篇
  1979年   63篇
  1978年   46篇
  1977年   45篇
  1974年   52篇
  1973年   40篇
  1972年   42篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Reviewing the definition of "elderly"   总被引:1,自引:0,他引:1  
Conventionally, "elderly" has been defined as a chronological age of 65 years old or older, while those from 65 through 74 years old are referred to as "early elderly" and those over 75 years old as "late elderly." However, the evidence on which this definition is based is unknown. We have attempted to review the definition of elderly by analyzing data from long-term longitudinal epidemiological studies, and clinical and pathological studies that have been accumulated at the Tokyo Metropolitan Geriatric Hospital and the Tokyo Metropolitan Institute of Gerontology. Our recommendation might be a starting point in developing a strategy for a successful society by reviewing the definition of elderly based on comprehensive evidence in all aspects of social, cultural and medical sciences.  相似文献   
22.
To clarify the genetic aberrations involved in the development and progression of hepatitis C virus-associated hepatocellular carcinoma (HCV-HCC), we investigated DNA copy number aberrations (DCNAs) in 19 surgically resected HCCs by conventional CGH and array CGH. Conventional CGH revealed that increases of DNA copy number were frequent at 1q (79% of the cases), 8q (37%), 6p (32%), and 10p (32%) and that decreases were frequent at 17p (79%), 16q (58%), 4q (53%), 13q (42%), 10q (37%), 1p (32%), and 8p (32%). In general, genes that showed DCNAs by array CGH were usually located in chromosomal regions with DCNAs detected by conventional CGH analysis. Increases in copy numbers of the LAMC2, TGFB2, and AKT3 genes (located on 1q) and decreases in copy numbers of FGR/SRC2 and CYLD (located on 1p and 16q, respectively) were observed in more than 30% of tumors, including small, well-differentiated carcinomas. These findings suggest that these genes are associated with the development of HCV-HCC. Increases of MOS, MYC, EXT1, and PTK2 (located on 8q) were detected exclusively in moderately and poorly differentiated tumors, suggesting that these alterations contribute to tumor progression. In conclusion, chromosomal and array CGH technologies allow identification of genes involved in the development and progression of HCV-HCC.  相似文献   
23.
The modulating effects of caffeine, nicotine, ethanol and sodium selenite on development of N-nitrosobis(2-oxopropyl)-amine (BOP)-initiated pancreatic tumors were investigated. Female Syrian golden hamsters were given s.c. injections of BOP (10 mg/kg body weight) or saline alone once a week for 3 weeks and then administered 2000 p.p.m. caffeine, 25 p.p.m. nicotine, 20% ethanol or 4 p.p.m. sodium selenite in their drinking water for the next 37 weeks. Control animals were given tap water alone after BOP initiation. Only the BOP-treated groups developed pancreatic adenocarcinomas and dysplasias. The multiplicity of pancreatic carcinomas was significantly higher (P less than 0.05) in animals receiving caffeine than in the controls. In addition, caffeine treatment slightly increased the incidence of carcinomas. Nicotine and ethanol also showed tendencies to enhance pancreatic carcinogenesis, although there were statistically no significant differences regarding lesion development. In contrast, sodium selenite administration was associated with a tendency for a decrease in the number of carcinomas and dysplasias. Thus, among these chemicals of obvious significance to human life-style, caffeine enhanced the development of pancreatic tumors when administered during the post-initiation phase in this hamster model.  相似文献   
24.
Background Although there have been reports dealing with ventricular diverticulum (VD) analyzed by cisternography and computed tomography (CT), those focusing on magnetic resonance imaging (MRI) or neuroendoscopic findings are rare. Case report We present a case of noncommunicating hydrocephalus caused by aqueductal stenosis with cystic lesion located in supracerebellar region. Third ventriculostomy was performed on this case. The conventional CT and MRI were compatible with usual VD, but neuroendoscopic examination suggested otherwise. The endoscopic view inside of the cystic lesion demonstrated passing veins and no membrane. We diagnosed this cystic lesion as a unique subtype of advanced VD mimicking spontaneous ventriculostomy. Endoscopic observation of the cyst was very useful for accurate diagnosis and safe treatment.  相似文献   
25.
A rare case of solitary bronchial papilloma was reported. A 57-year-old male was admitted to our hospital because of an abnormal shadow on chest X-ray film which was discovered on regular health check up. Bronchoscopic examination revealed a polypoid tumor which obstructed the left B4 bronchus. Serum concentration of CEA was elevated up to 14 ng/ml by Z-GEL method. Left upper lobectomy was performed. On macroscopic examination of the excised specimen, the tumor arose in B4 bronchus and was yellowish white in color and was cauliflower-like in shape sized 3.5 X 1.5 cm. Histopathologically, the tumor consisted of papillary proliferation of stratified squamous epithelium with ciliated columnar epithelial covering. Findings suggestive of inflammation or malignancy were not observed.  相似文献   
26.
Absorption of tetrahydropyranyl adriamycin (THP) administered immediately after transurethral resection of bladder carcinoma (TUR-Bt) has not been reported. In this study, we have examined the absorption of THP and the systemic toxicity in the early post-TUR period. Of 21 patients with bladder carcinoma, 10 had a solitary tumor and 11 multiple tumors. Twenty mg THP in 40 ml of sterile water was intravesically administered on days 1, 3, 5, 7, 14 and 28, and then every 4th week. The THP solution was retained for 2 hours. The blood THP concentration was measured 30 minutes and 2 hours after the intravesical administration on days 1, 7 and 28. No systemic side effects were observed. Thirteen of the 38 (34%) samples contained a detectable level (more than 1 ng/ml) of THP on the post-TUR-Bt on day 1, 8, of 42 (19%) on day 7, and 3 of 18 (17%) on day 28. Altogether, 24 of the 98 (24%) samples contained more than 1 ng/ml THP. The highest blood THP level was 23 ng/ml on day 1. The differences between frequency of detection of blood THP in the samples at 30 minutes and 2 hours were not statistically significant. The difference between average concentration of blood THP of patients with solitary and multiple tumors also was not significant. These results indicate that intravesical THP administration starting within 24 hours after TUR-Bt can not result in significant systemic absorption of THP, and the systemic toxicity can be avoided.  相似文献   
27.
1. The effects of acute bilateral superior cervical ganglionectomy on cerebral blood flow and metabolism were investigated in stroke-prone spontaneously hypertensive rats (SHRsp), before and during cerebral ischaemia. 2. The resting cerebral blood flow was comparable between the control and denervated animals. 3. There was no significant difference in cerebral blood flow or concentration of tissue energy metabolites (adenosine triphosphate [ATP], lactate and pyruvate) between the sham-operated control and denervated animals during ischaemia. 4. The results suggest that sympathetic innervation of cerebral vessels originating from superior cervical ganglia may not play a major role in the progression of cerebral ischaemia in SHRsp.  相似文献   
28.
A total 37 patients with Crohn's disease who underwent intraoperative endoscopy during resection of the affected intestine were evaluated in this study. The average age of the patients at surgery was 23.2 years. The residual lesions in the remaining intestine identified by intraoperative endoscopy were classified according to their pathologic profiles into three groups: A, B and C. In group A, comprising patients with longitudinal ulcers and/or a cobblestone appearance, 10 of 12 patients had recurrence. In 5 of these 10, the residual lesions were exacerbated and 2 required a further operation. The remaining 5 patients showed recurrence at the site of previous anastomosis and 2 of these 5 required additional surgery.In group B, comprising patients with small ulcers, aphthoid ulcers, or scars, and group C, comprising patients with no residual lesions, recurrence was observed in 13 of 16, and 3 of 9 patients, respectively. The recurrent lesions were all found proximal to, or at the site of previous anastomosis. Additional operations were performed on 3 of the group B patients. The findings of this study revealed that recurrence requiring additional surgery is more frequent at the site of anastomosis, regardless of the endoscopic appearance of the residual lesions.  相似文献   
29.
30.
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