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   250951篇
  免费   12952篇
  国内免费   393篇
耳鼻咽喉   3801篇
儿科学   9097篇
妇产科学   8654篇
基础医学   37035篇
口腔科学   6606篇
临床医学   20379篇
内科学   46891篇
皮肤病学   5384篇
神经病学   17636篇
特种医学   9759篇
外国民族医学   31篇
外科学   39865篇
综合类   6433篇
现状与发展   2篇
一般理论   130篇
预防医学   16423篇
眼科学   5907篇
药学   17434篇
  4篇
中国医学   720篇
肿瘤学   12105篇
  2021年   2021篇
  2019年   2026篇
  2018年   3248篇
  2017年   2430篇
  2016年   2806篇
  2015年   3072篇
  2014年   4057篇
  2013年   6325篇
  2012年   8094篇
  2011年   8429篇
  2010年   5386篇
  2009年   4710篇
  2008年   7544篇
  2007年   8439篇
  2006年   8226篇
  2005年   7970篇
  2004年   7626篇
  2003年   7223篇
  2002年   6903篇
  2001年   11000篇
  2000年   11302篇
  1999年   9512篇
  1998年   2533篇
  1997年   2314篇
  1996年   2171篇
  1995年   2103篇
  1994年   1918篇
  1992年   6748篇
  1991年   6805篇
  1990年   6627篇
  1989年   6528篇
  1988年   5912篇
  1987年   5733篇
  1986年   5437篇
  1985年   5257篇
  1984年   3782篇
  1983年   3300篇
  1982年   2000篇
  1979年   3504篇
  1978年   2567篇
  1977年   2176篇
  1976年   2006篇
  1975年   2272篇
  1974年   2689篇
  1973年   2704篇
  1972年   2488篇
  1971年   2360篇
  1970年   2296篇
  1969年   2119篇
  1968年   2069篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
The influence of new derivatives of 9,10-anthraquinone with benzoylthiourea, thiazole, triazole and amino acid fragments on the activity of membrane-associated tyrosine kinases was investigated. Inhibitors of protein tyrosine kinase activity of the membrane fraction, as promising agents to search for new potential anticancer agents among the studied compounds, were discovered.  相似文献   
993.
994.
995.
996.
Cetingoz R  Kentli S  Uruk O  Demirtas E  Sen M  Kinay M 《Neoplasma》2001,48(6):506-510
The aim of this study was to evaluate retrospectively the treatment results of non-small cell lung cancer (NSCLC) patients treated with palliative intent in Dokuz Eylul University Hospital, Radiation Oncology Department. One hundred and fifteen inoperable, non-metastatic and symptomatic NSCLC patients were treated with palliative radiotherapy (PRT) between July 1991 and May 2000. PRT was used in patients with low performance status, weight loss more than 10% within last 6 months, secondary malignancies, co-morbid diseases and socio-economic problems. Parallelly opposed isocentric antero-posterior fields including both the parenchymal and mediastinal masses were used. 10-55 Gy total doses were delivered in 1-23 fractions with a median of 30 Gy. Nineteen patients received systemic chemotherapy before PRT. Survival analysis was made from the treatment beginning date, and subjective palliation rates were assessed according to clinical improvements in symptomatology evaluated 1-6 weeks after PRT. The median follow-up time was 28 weeks (1-234 weeks). Totally, 245 disease-related symptoms were detected in 115 patients. Overall "improvement" in symptomatology was found to be 90% (221/245) with a "near-total response" rate of 46% (113/245). Hemoptysis was the best palliated symptom. Median survival time was 30 weeks. Karnofsky performance status (KPS) (p=0.015), weight loss (p=0.0015), histologic tumor type (p=0.0024) and tumor size (p=0.02) were found to effect overall survival rates significantly in uni-variant analysis. Multi-variant analysis revealed statistically significant effect with histological tumor type and weight loss status. Only 16% of patients (3/19) showed partial and 5% (1/19) complete response to systemic treatment. Median survival time was 46 weeks in this group. In conclusion, this retrospective study of patients with poor prognostic factors confirms that PRT is an effective treatment modality in symptomatic locally advanced NSCLC patients resulting in 90% symptomatic improvement rate and a median survival of 30 weeks.  相似文献   
997.
Medical therapy for reflux esophagitis: 1986 and beyond   总被引:1,自引:0,他引:1  
  相似文献   
998.
The postviral fatigue syndrome — an analysis of the findings in 50 cases   总被引:23,自引:0,他引:23  
The clinical, pathological, electrophysiological, immunological and virological abnormalities in 50 patients with the postviral fatigue syndrome are recorded. These findings confirm the organic nature of the disease. A metabolic disorder, caused by persistent virus infection and associated with defective immunoregulation, is suggested as the pathogenetic mechanism.  相似文献   
999.
J O Kokkonen 《Atherosclerosis》1989,79(2-3):213-223
The effect of mast cell stimulation on the uptake of low density lipoproteins (LDL) by macrophages was tested in vivo in the peritoneal cavity of the rat, a site known to contain both macrophages and mast cells. The concentration of LDL in the peritoneal cavity was raised by injecting [14C]sucrose-labeled LDL ([14C]sucrose-LDL). In the treated rats, in the absence of mast cell stimulation, the uptake of LDL by the peritoneal macrophages was low. But when the peritoneal mast cells were concomitantly stimulated by intraperitoneal administration of compound 48/80, an agent known to induce mast cell degranulation, the rate of uptake of labeled LDL by macrophages rose by 7-24-fold. The reason for this rise was that exocytosed mast cell granules bound LDL and carried it into macrophages when phagocytosed. Thus, cyclohexanedione treatment of LDL, or injection of avidin along with LDL, 2 measures known to inhibit binding of LDL to mast cell granules, totally prevented the mast cell-dependent uptake of LDL. Furthermore transmission electron microscopic studies with gold-labeled LDL disclosed phagocytosis of LDL-bearing granules by the peritoneal macrophages. This is the first demonstration of a natural proteoglycan being able to enhance the rate of LDL uptake by macrophages in vivo. These observations on the relation between stimulation of mast cells and uptake of LDL by macrophages in vivo may have relevance in other sites where mast cells and macrophages coexist, such as the arterial intima.  相似文献   
1000.
The association between glomerular disease and hepatosplenic schistosomiasis is well documented in reports from South America. During the present hospital investigation in Sudan, 58 patients admitted for intercurrent complications of advanced hepatosplenic schistosomiasis were studied. The patients, median age 35 years, had no concurrent Schistosoma haematobium infection. Diagnostic criteria included an enlarged spleen (n = 58), at least 1 episode of hematemesis (n = 55) and/or melena (n = 36), endoscopical demonstration of gastroesophageal varices (29/29 studied), ultrasonographical imaging of hepatic periportal fibrosis (18/18 studied), and intraoperative liver biopsy with characteristic histological findings (11/16 biopsied). Serum creatinine, urea, electrolytes, cholesterol, total protein, and electrophoresis were within normal limits. Median urinary protein/creatinine ratio was 0.06 and thereby not significantly different from European reference values. Only 1 patient had proteinuria of 1.7 g/l. Minimal hematuria was found in 5 patients. Ten kidney biopsies were taken intraoperatively during a portal decompression procedure (Hassab operation). Light, immunofluorescence, and electron microscopy produced no evidence of glomerulonephritis. These findings indicate that S. mansoni induced nephrotic syndrome may be less frequent in Sudan than in South America. Renal involvement due to S. mansoni infection may therefore encompass geographical variances.  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