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   942篇
  免费   67篇
  国内免费   12篇
耳鼻咽喉   43篇
儿科学   9篇
妇产科学   11篇
基础医学   139篇
口腔科学   15篇
临床医学   52篇
内科学   277篇
皮肤病学   5篇
神经病学   66篇
特种医学   35篇
外科学   166篇
综合类   9篇
预防医学   10篇
眼科学   27篇
药学   54篇
中国医学   6篇
肿瘤学   97篇
  2024年   2篇
  2023年   9篇
  2022年   13篇
  2021年   32篇
  2020年   22篇
  2019年   21篇
  2018年   28篇
  2017年   33篇
  2016年   27篇
  2015年   34篇
  2014年   51篇
  2013年   53篇
  2012年   84篇
  2011年   68篇
  2010年   41篇
  2009年   44篇
  2008年   55篇
  2007年   73篇
  2006年   48篇
  2005年   58篇
  2004年   51篇
  2003年   43篇
  2002年   48篇
  2001年   11篇
  2000年   9篇
  1999年   7篇
  1998年   9篇
  1997年   9篇
  1996年   6篇
  1995年   2篇
  1994年   6篇
  1993年   3篇
  1992年   3篇
  1991年   1篇
  1988年   1篇
  1987年   1篇
  1986年   2篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   2篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1974年   1篇
  1973年   1篇
  1955年   1篇
排序方式: 共有1021条查询结果,搜索用时 31 毫秒
41.
42.
Primary malignant melanoma of the esophagus is uncommon, and its prognosis is poor compared to that of cutaneous malignant melanoma. Here we describe a case of primary malignant melanoma of the esophagus with a long-term survival. A 52-year-old woman received an upper gastrointestinal endoscopy and an upper gastrointestinal series for a dull back pain and dysphagia. A pigmented polypoid tumor in the esophagus was discovered and diagnosed pathologically as a malignant melanoma on the biopsied specimen. After effective chemotherapy with cisplatin (CDDP), the patient underwent surgical operation. A subtotal esophagectomy with three-field lymph node dissection was performed through a right thoracotomy. No distant metastasis including liver and lung was found, and histopathological examination revealed no lymph node metastasis. Postoperatively, six courses of chemotherapy with CDDP were performed. The patient has been alive without any problems for more than 11 years postoperatively.  相似文献   
43.
To clarify whether probucol and statins suppress oxidative stress in diabetic patients, we studied the effects of probucol and the statin atorvastatin on urinary 8-hydroxy-2'deoxyguanosine (8-OHdG) levels in diabetics with hypercholesterolemia. A randomized, open study was performed on a total of 36 patients with type 2 diabetes and hypercholesterolemia. The patients were randomly assigned to a probucol group (500 mg/day, n = 18) or an atorvastatin group (10 mg/day, n = 18). During three months, total- and LDL-cholesterol decreased significantly in both groups. LDL-cholesterol was significantly lower in the atorvastatin group than probucol group. HDL-C decreased significantly in the probucol group and did not change in the atorvastatin group. 8-OHdG decreased significantly in both groups after 3 months; 12.4 +/- 7.5 to 8.1 +/- 4.2 ng/mg/Cr in the atorvastatin group (p < 0.05) and 12.3 +/- 8.8 to 6.8 +/- 2.6 ng/mg/Cr in the probucol group (p < 0.05), and these changes did not differ significantly between the two groups. But, in patients with high 8-OHdG levels (more than 10 ng/mg/Cr) before administration, urinary 8-OHdG decreased significantly from 19.5 +/- 4.9 to 9.2 +/- 3.4 ng/mg Cr (p < 0.01) in the atorvastatin group, and from 19.7 +/- 8.2 to 6.67 +/- 2.2 ng/mg Cr (p < 0.01) in the probucol group. Urinary 8-OHdG was significantly lower in the probucol group than in the atorvastatin group after the second and third months of administration (p < 0.05). These results suggest that while probucol and atorvastatin both reduce systemic oxidative stress, probucol might be the more useful in patients with strong oxidative stress.  相似文献   
44.
45.
Background and Aims: We investigated the efficacy of intra‐arterial 5‐fluorouracil (5‐FU) and systemic interferon (IFN)‐α (5‐FU‐IFN) in the treatment of hepatocellular carcinoma (HCC) with portal vein tumor thrombosis in the first branch or trunk (Vp3/4) and extrahepatic metastases. Methods: We examined 17 HCC patients with Vp3/4 and extrahepatic metastases (meta group) and 31 HCC patients with Vp3/4 (non‐meta group). Baseline intrahepatic tumor factors and the hepatic reserve were similar between groups. The extrahepatic metastases of the meta group were not considered prognostic factors. Following the administration of 5‐FU/IFN to all patients, we compared the survival rates, response, time to progression (TTP), and safety between groups. Results: For intrahepatic HCC, complete response, partial response, stable disease, progressive disease, and drop out were observed in no (0%), one (6%), seven (41%), nine (53%), and no (0%) patients of the meta group, and in five (16%), seven (23%), 13 (42%), five (16%) and one (3%) patient of the non‐meta group, respectively. The response rate was significantly lower in the meta group (6% vs 39%, P = 0.018). The median TTP of intrahepatic HCC and the median survival time were significantly shorter in the meta group than in the non‐meta group (1.6 vs 6.3 months, P = 0.0001, and 3.9 months vs 10.5 months, P < 0.0001, respectively). The multivariate analysis showed that the absence of extrahepatic metastases was a significant and independent determinant of both TTP of intrahepatic HCC (P < 0.001) and overall survival (P < 0.001). No patient died of extrahepatic HCC‐related disease. Conclusions: The efficacy of 5‐FU/IFN for advanced HCC with Vp3/4 and extrahepatic metastases was markedly limited.  相似文献   
46.
SAP-1 (PTPRH) is a receptor-type protein tyrosine phosphatase (RPTP) with a single catalytic domain in its cytoplasmic region and fibronectin type III-like domains in its extracellular region. The cellular localization and biological functions of this RPTP have remained unknown, however. We now show that mouse SAP-1 mRNA is largely restricted to the gastrointestinal tract and that SAP-1 protein localizes to the microvilli of the brush border in gastrointestinal epithelial cells. The expression of SAP-1 in mouse intestine is minimal during embryonic development but increases markedly after birth. SAP-1-deficient mice manifested no marked changes in morphology of the intestinal epithelium. In contrast, SAP-1 ablation inhibited tumorigenesis in mice with a heterozygous mutation of the adenomatous polyposis coli gene. These results thus suggest that SAP-1 is a microvillus-specific RPTP that regulates intestinal tumorigenesis.  相似文献   
47.
48.
The effects of methionine on hepatocarcinogenesis induced by Coadministration of a choline-deflcient L-amino acid-defined (CDAA) diet and ethionine were examined. F344 male rats were divided into 4 experimental groups. Groups 1 and 2 received the CDAA diet and a choline-supplemented L-amino acid-defined (CSAA) diet, respectively. Group 3 received the CDAA diet containing 0.05% ethionine, and group 4 the CDAA diet containing 0.05% ethionine and 0.47% methionine. Animals were killed after 12 weeks of treatment. Histologically, the CDAA diet induced intracellular fat accumulation and foci. In contrast, ethionine caused not only foci, but also hyperplastic nodules, cholangiofibrosis and the proliferation of oval cells without such fat accumulation. Methionine abolished the development of all of the liver lesions induced by Coadministration of the CDAA diet and ethionine. To investigate the effects of methionine on induction of c- myc and c-Ha- ras expression, as well as generation of 8-hydroxyguanine (8-OHGua) and 2-thiobarbituric acid-reacting substances (TBARS), by Coadministration of the CDAA diet and ethionine, subgroups of 3 to 5 animals were killed at 2, 4, 8 or 11 days after the beginning of the experiment. Coadministration of the CDAA diet and ethionine markedly enhanced the level of expression of c- myc and c-Ha- ras , 8-OHGua formation and TBARS generation as compared with the CDAA or CSAA diet within 11 days, and methionine blocked these actions. These results indicate that addition of methionine prevents the induction of c- myc and c-Ha- ras expression, 8-OHGua formation and TBARS generation, as well as hepatocellular lesions, by Coadministration of the CDAA diet and ethionine in rats, and suggest a possible involvement of oxidative stress and gene expression in hepatocarcinogenesis by these agents.  相似文献   
49.
This retrospective analysis was performed to determine the early and late outcome in patients 70 years and older undergoing aortic valve replacement (AVR). From October 1994 to May 2001, 49 patients (24 men and 25 women, age 70 to 88 years [mean 74 +/- 4.6 years]) underwent primary AVR with or without concomitant procedures. Twenty-one received mechanical valves and 28 bioprostheses. Age was different between both groups: 72 +/- 2.3 years (mechanical) and 76 +/- 5.1 years (bioprosthetic) (p = 0.0005). Aortic stenosis was present in 25 patients (51%). Follow-up was 100% complete at a mean follow-up of 2.9 years (range 0.3-6.5 years). Overall hospital mortality was 4.1% (2/49). There were no postoperative complications in 24% of patients. Postoperative hospital stay or hospital survival was 27 +/- 13 days. Survival at 3 and 5 years was 89 +/- 5% and 80 +/- 7%, respectively. Three late deaths were due to noncardiac causes and 1 each had a cardiac or valve-related cause (thromboembolism). Other valve-related complications such as anticoagulant-related hemorrhage, perivalvular leak, endocarditis, prosthetic valve failure, and reoperation were not noted in any of the 49 patients. The actuarial survival curve was similar in each group of bioprosthetic versus mechanical and septuagenarians versus octogenarians. Under the selection criteria for AVR currently applied in our hospital, geriatric patients showed a satisfactory early outcome and medium-term survival benefit.  相似文献   
50.
The phenolic active metabolites, cis-4-hydroxytamoxifen (cis-HO-TAM) and trans-4-hydroxytamoxifen (trans-HO-TAM), of the anti-breast-cancer drug, trans-tamoxifen (TAM), were geometrically selectively glucuronidated in the manner of cis>trans by microsomes and sulfated in the manner of trans>cis by cytosol from the liver of 10 human subjects (7 females and 3 males). There was a large individual difference in the microsomal glucuronidation of cis-HO-TAM, which correlated well with glucuronidation of 4-hydroxybiphenyl by human liver microsomes. However, there was only a slight correlation between the glucuronidation of cis-HO-TAM and trans-HO-TAM or 4-nitrophenol (NP). A small individual difference was observed for the human liver cytosolic sulfation of trans-HO-TAM, which correlated well with the sulfation of NP. Recombinant human UDP-glucuronosyltransferase (UGT)2B15 catalyzed the cis-selective glucuronidation of geometrical isomers of HO-TAM. UGTs1A1, 1A4, 1A9 and 2B7 had weak activity toward HO-TAMs with a much smaller cis-selectivity than did UGT2B15. UGTs1A3 and 1A6 had no detectable activity toward these substrates. Among the four known major sulfotransferases (SULTs) occurring in the human liver, SULT1A1 was strongly suggested to play the most important role in the hepatic cytosolic trans-selective sulfation of HO-TAM isomers. A good correlation was observed between the hepatic cytosolic sulfation of trans-HO-TAM and NP, a standard substrate for SULT1A1. SULT1E1 had slight activity toward the HO-TAMs. SULTs1A3 and 2A1 had no detectable activity toward HO-TAMs.  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