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   2449篇
  免费   317篇
  国内免费   6篇
耳鼻咽喉   23篇
儿科学   68篇
妇产科学   87篇
基础医学   363篇
口腔科学   74篇
临床医学   249篇
内科学   403篇
皮肤病学   98篇
神经病学   143篇
特种医学   134篇
外科学   308篇
综合类   87篇
预防医学   280篇
眼科学   87篇
药学   138篇
中国医学   2篇
肿瘤学   228篇
  2021年   24篇
  2018年   38篇
  2017年   29篇
  2016年   40篇
  2015年   29篇
  2014年   45篇
  2013年   73篇
  2012年   75篇
  2011年   95篇
  2010年   81篇
  2009年   67篇
  2008年   71篇
  2007年   88篇
  2006年   119篇
  2005年   85篇
  2004年   118篇
  2003年   92篇
  2002年   75篇
  2001年   66篇
  2000年   74篇
  1999年   53篇
  1998年   52篇
  1997年   50篇
  1996年   38篇
  1995年   54篇
  1994年   45篇
  1993年   28篇
  1992年   48篇
  1991年   60篇
  1990年   40篇
  1989年   54篇
  1988年   51篇
  1987年   33篇
  1986年   55篇
  1985年   32篇
  1984年   39篇
  1983年   41篇
  1982年   29篇
  1981年   32篇
  1980年   25篇
  1979年   37篇
  1978年   27篇
  1976年   35篇
  1975年   29篇
  1974年   24篇
  1972年   43篇
  1971年   28篇
  1970年   30篇
  1967年   25篇
  1966年   26篇
排序方式: 共有2772条查询结果,搜索用时 15 毫秒
51.
Mastectomy probably represents over-treatment for the majority of women with screen detected ductal carcinoma in situ (DCIS) and breast-conserving surgery is now widely advocated. In this study, biopsy cavity shavings were used to ensure complete excision in 129 women undergoing breast-conserving surgery for screen detected DCIS. A margin was considered clear if DCIS was > 1 mm from any margin of excision and shavings were clear. Patients with involved margins (DCIS at resection margin) underwent re-excision, irrespective of shaving status. After re-excision, 101 women (78%) had clear margins and 28 (22%) close margins (DCIS < or = 1 mm from resection margin). Cavity shavings were histologically clear of DCIS in all cases. Ipsilateral DCIS recurrence occurred in 12 (9.3%) patients. Two recurrences also contained invasive carcinoma. The median time to diagnosis was 14 months and all recurrences occurred at the site of the previous biopsy. Seven recurrences were detected at the first annual mammogram, four at the second and one at the third. Ipsilateral recurrence was related to margin status; only 2 out of 101 (2%) patients with clear margins recurred, compared with 10 out of 28 (36%) patients with close margins. Local recurrence and close margin status both correlated with a high modified Van Nuys prognostic index score. Our results indicate that local relapse represents residual DCIS rather than true recurrence in the majority of cases. Cavity shavings have proved ineffective in ensuring complete excision. We now ensure a minimum 10 mm margin of excision around all screen-detected DCIS lesions.  相似文献   
52.
53.
PURPOSE: Biliary cancer has a poor prognosis, and chemotherapy has had little impact. The objectives of this trial were to determine the response rate, time to disease progression, survival, and safety profile of the combination of gemcitabine and capecitabine (GemCap) in patients with advanced biliary cancer. PATIENTS AND METHODS: Eligible patients had pathologically proven, locally advanced or metastatic adenocarcinoma arising from the intra- and extrahepatic bile ducts or gallbladder with no prior chemotherapy. Patients were treated on a 3-week cycle consisting of capecitabine at 650 mg/m(2) orally twice a day for 14 days and gemcitabine at a fixed dose of 1,000 mg/m(2) intravenously over 30 minutes on days 1 and 8. RESULTS: Forty-five patients were enrolled between July 2001 and January 2004. Fifty-three percent of patients had cholangiocarcinoma, 47% had gallbladder cancer, and 89% had metastatic disease. The overall objective response rate was 31%, with an additional 42% of patients with stable disease, for a disease control rate of 73%. The median overall survival time was 14 months (95% CI, 7.3 months to not available), and the median progression-free survival time was 7 months (95% CI, 4.6 to 11.8 months). This chemotherapy combination was generally well tolerated. Transient neutropenia, thrombocytopenia, fatigue, and hand-foot syndrome were commonly observed but were easily managed without discontinuing further treatment. CONCLUSION: The significant antitumor activity combined with a mild toxicity profile seen in this study argue that GemCap chemotherapy may benefit patients with advanced biliary cancer. This regimen warrants further evaluation in a randomized study with survival and quality of life end points.  相似文献   
54.
Polymorphisms in the promoter of the BRM gene, a critical subunit of the chromatin remodeling SWI/SNF complex, have previously been implicated in risk and prognosis in Caucasian‐predominant lung, head and neck, esophageal, and pancreatic cancers, and in hepatocellular cancers in Asians. We investigated the role of these polymorphisms in hepatocellular carcinoma (HCC) risk and prognosis. HCC cases were recruited in a comprehensive cancer center while the matched controls were recruited from family practice units from the same catchment area. For risk analyses, unconditional logistic regression analyses were performed in HCC patients and matched healthy controls. Overall survival analyses were performed using Cox proportional hazard models, Kaplan‐Meier curves, and log‐rank tests. In 266 HCC cases and 536 controls, no association between either BRM promoter polymorphism (BRM‐741 or BRM‐1321) and risk of HCC was identified (P > 0.10 for all comparisons). There was significant worsening of overall survival as the number of variant alleles increased: BRM‐741 per variant allele adjusted hazards ratio (aHR) 5.77, 95% confidence interval (CI) 2.89‐11.54 and BRM‐1321 per variant allele aHR 4.09, 95%CI 2.22‐7.51. The effects of these two polymorphisms were at least additive, where individuals who were double homozygotes for the variant alleles had a 45‐fold increase in risk of death when compared to those who were double wild‐type for the two polymorphisms. Two BRM promoter polymorphisms were strongly associated with HCC prognosis but were not associated with increased HCC susceptibility. The association was strongest in double homozygotes for the allele variants.  相似文献   
55.
56.
57.
58.
59.
60.
Spores of some species of the strictly anaerobic bacteria Clostridium naturally target and partially lyse the hypoxic cores of tumors, which tend to be refractory to conventional therapies. The anti-tumor effect can be augmented by engineering strains to convert a non-toxic prodrug into a cytotoxic drug specifically at the tumor site by expressing a prodrug-converting enzyme (PCE). Safe doses of the favored prodrug CB1954 lead to peak concentrations of 6.3 μM in patient sera, but at these concentration(s) known nitroreductase (NTR) PCEs for this prodrug show low activity. Furthermore, efficacious and safe Clostridium strains that stably express a PCE have not been reported. Here we identify a novel nitroreductase from Neisseria meningitidis, NmeNTR, which is able to activate CB1954 at clinically-achievable serum concentrations. An NmeNTR expression cassette, which does not contain an antibiotic resistance marker, was stably localized to the chromosome of Clostridium sporogenes using a new integration method, and the strain was disabled for safety and containment by making it a uracil auxotroph. The efficacy of Clostridium-Directed Enzyme Prodrug Therapy (CDEPT) using this system was demonstrated in a mouse xenograft model of human colon carcinoma. Substantial tumor suppression was achieved, and several animals were cured. These encouraging data suggest that the novel enzyme and strain engineering approach represent a promising platform for the clinical development of CDEPT.  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