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   8189篇
  免费   464篇
  国内免费   330篇
耳鼻咽喉   164篇
儿科学   120篇
妇产科学   234篇
基础医学   468篇
口腔科学   161篇
临床医学   476篇
内科学   1381篇
皮肤病学   39篇
神经病学   276篇
特种医学   128篇
外科学   1530篇
综合类   638篇
预防医学   516篇
眼科学   24篇
药学   296篇
中国医学   62篇
肿瘤学   2470篇
  2024年   7篇
  2023年   150篇
  2022年   379篇
  2021年   499篇
  2020年   397篇
  2019年   411篇
  2018年   432篇
  2017年   315篇
  2016年   296篇
  2015年   344篇
  2014年   668篇
  2013年   546篇
  2012年   415篇
  2011年   515篇
  2010年   332篇
  2009年   445篇
  2008年   482篇
  2007年   420篇
  2006年   300篇
  2005年   238篇
  2004年   212篇
  2003年   149篇
  2002年   114篇
  2001年   124篇
  2000年   107篇
  1999年   117篇
  1998年   67篇
  1997年   65篇
  1996年   47篇
  1995年   46篇
  1994年   41篇
  1993年   31篇
  1992年   35篇
  1991年   23篇
  1990年   24篇
  1989年   33篇
  1988年   22篇
  1987年   21篇
  1986年   16篇
  1985年   21篇
  1984年   14篇
  1983年   16篇
  1982年   13篇
  1981年   10篇
  1980年   11篇
  1979年   4篇
  1978年   3篇
  1977年   3篇
  1973年   1篇
  1970年   1篇
排序方式: 共有8983条查询结果,搜索用时 0 毫秒
51.
Background: Traditional teaching maintains that patients with primary colorectal adenocarcinoma require timely resection to prevent bleeding, perforation, or obstruction. The true benefits of primary tumor resection remain undocumented for patients presenting with metastatic disease, however. We postulated that resection of primary colorectal tumors could be avoided safely in a select population of asymptomatic colorectal cancer patients presenting with incurable stage IV disease.Methods: A retrospective review of the Vanderbilt University Hospital tumor registry was performed for the years 1985 to 1997. During this period, 955 patients presented for management of primary colorectal cancer. From this group, all patients with stage IV disease at the time of diagnosis were identified. Patients who initially underwent resection of their primary lesion were included in the resection group; those who underwent initial nonoperative primary tumor management were included in the nonresection group. Data were obtained regarding age, extent of disease, nonsurgical therapy, tumor-specific complications, and palliative surgical procedures. Surgery-free survival and overall survival were analyzed using the Kaplan-Meier method. For patients with liver metastases, hepatic tumor burden was defined as either H1 (<25% parenchymal replacement), H2 (25% to 50%), or H3 (>50%) disease.Results: Sixty-six patients were included in the resection group, and 23 patients with intact asymptomatic primary colorectal lesions were included in the nonresection group. Among patients with hepatic metastases, most of the patients in both groups had H1 disease. Ten patients in the resection group and 3 patients in the nonresection group presented with exclusively extrahepatic metastases. In the nonresection group, primary therapy included chemotherapy in 13 patients, external beam radiation therapy in 1 patient, and combination chemoradiation in 9 patients. The median survival in the nonresection group was 16.6 months. The 2-year actuarial survival was 18%, and the surgery-free survival was 91.3%. Only 2 of 23 patients (8.7%) managed without resection eventually developed obstruction at the primary tumor site requiring emergent diversion. There were no episodes of tumor-related hemorrhage or perforation. For the resection group, the operative morbidity was 30.3%, and the perioperative mortality rate was 4.6%. The median survival in the resection group was 14.5 months (P = 0.59, log-rank test vs. nonresection group).Conclusions: Selected patients with asymptomatic primary colorectal tumors who present with incurable metastatic disease may safely avoid resection of their primary lesions, with an anticipated low rate of hemorrhage, perforation, or obstruction before death from systemic disease. No survival advantage is gained by resection of an asymptomatic primary lesion in the setting of incurable stage IV colorectal cancer.  相似文献   
52.
The authors present the AIDS cases (CDC '93) observed in Brescia from 1983 to 1994. They observed 1189 subjects (M 84%, F 16%) with a mean age of 32.7 years (intra-venous drug users 75.1%, heterosexuals 14%, homosexuals 9.6%). The mean survival observed was 56.7 weeks from the diagnosis of AIDS (mortality per year 78%). The most frequent AIDS-defining events were Visceral Candidiasis, P.carinii Pneumonia (PCP) and Neurotoxoplasmosis, while the longest and shortest mean survival was for Kaposi's Sarcoma (89 weeks) and Wasting Syndrome (8.4). The mean value of CD4+ lymphocyte counts on AIDS diagnosis was 72.6/l (1166 cases) and the highest and lowest were in non-Hodgkin's Lymphoma (NHL; 147.6/l) and Cryptosporidiosis (18.8/l). Antiretroviral therapy had been given for at least a month in 41.4% subjects (mean treatment duration of 74.8 weeks). The Cox model has demonstrated the favourable effect on survival of high CD4+ lymphocyte counts on diagnosis, antiretroviral therapy, the diagnosis of Tuberculosis (TBC) and PCP as initial markers and the diagnosis of TBC, PCP or Cytomegalovirus infection (CMV) during the entire clinical evolution. Moreover, the unfavourable effect of high age, diagnosis of Progressive Multifocal Leucoencephalopathy (PML), Wasting Syndrome and NHL as initial markers and diagnosis of PML or NHL in any moment of the disease has been demonstrated.  相似文献   
53.
Oxygen free radicals (OFRs) have been reported to play pivotal roles in the pathogenesis of cell damage induced by ischemia and reperfusion. The efficacy of recombinant human superoxide dismutase (rh-SOD) in the treatment of circulatory disorders after reperfusion of the splanchnic area was investigated in rats. All rats died within 3 hours after release of 60-min superior mesenteric artery occlusion (SMAO) when no treatment was given. Animals which received rh-SOD, 2mg·100g–1BW, at reperfusion followed by a continuous infusion of rh-SOD 0.67mg·100g–1BW·hr–1, exhibited prolonged survival times compared with no treatment rats (231 ± 35min and 149 ± 43min, respectively). Mean blood pressure in rats treated with rh-SOD was higher than in controls after reperfusion, and was concomitant with improvement in splanchnic perfusion. The results suggest excessive activity of OFRs in reperfused organs and a possible scavenging effect of rh-SOD as a means of eliminating them.(Bitoh H: Recombinant human-type SOD attenuates circulatory disorders after reperfusion of splanchnic organs in rats. J Anesth 6: 247–254, 1992)  相似文献   
54.
目的总结大量临床肾移植工作和提高移植肾存活率的经验。方法回顾5个年度中609例次异体肾移植临床资料,分析供、受者情况、组织配型、移植手术过程、免疫移植治疗、移植并发症等影响移植效果的因素,观察年度内人/肾存活率和术后转归。结果5个年度内共计发生术后并发症121例,以感染和外科并发症最常见。死亡患者28例,移植肾切除数34例,年度内人/肾成活率平均分别为95.40%和94.42%。结论高质量取肾、修肾、植肾手术及良好的组织配型和规范的术后处理,是提高临床移植肾存活率的关键。  相似文献   
55.
Hemodialysis in elderly patients   总被引:1,自引:0,他引:1  
International Urology and Nephrology -  相似文献   
56.
目的 探讨胆囊癌的临床治疗方法及其预后。方法 回顾性分析 161例胆囊癌的临床资料 ,其中单纯胆囊切除 48例 ,根治性胆囊癌切除 41例 ,胆囊癌扩大切除 2 0例 ,胆囊加胰十二指肠切除 3例 ,单纯探查术 7例 ,介入及放化疗 42例。随访 6个月至 5年。结果 行探查术患者 1年内全部死亡 ,单纯胆囊切除和根治性胆囊癌切除患者的 5年生存率分别为 69%、5 9% ,放疗和介入治疗患者的 5年生存率为 0。结论 胆囊癌早期发现 ,并行根治性切除 ,可显著提高 5年生存率  相似文献   
57.
AIM: Large multicenter, randomized trials have revealed the advantages of using tamoxifen for 5 years vs 2 years in breast cancer patients. The aim of this report is to confirm the optimal duration of tamoxifen administration in a study of Japanese breast cancer patients. METHODS: Japanese post-menopausal estrogen receptor-positive breast cancer patients treated with mastectomy were randomly assigned to either a 5-year or 2-year course of tamoxifen. The primary endpoint was disease-free survival, with secondary endpoints of overall survival and a reduction in the development of metachronous contra-lateral breast cancer. RESULTS: A total of 256 breast cancer patients were randomized to a 5-year or 2-year tamoxifen administration group. After a median follow-up time of 81 months, there were no significant differences seen in terms of disease-free or overall survival (p=0.65 and 0.56, respectively). Furthermore, the impact of the 5-year use of tamoxifen on the development of contra-lateral breast cancer did not reach statistical significance (p=0.0511). However, 5-year tamoxifen use was closely associated with gynaecological complications (p=0.0081). CONCLUSION: We could not show a beneficial effect of using tamoxifen for 5 years over 2 years in Japanese estrogen receptor-positive patients. This is likely due to the small number of patients enrolled in our study; however, racial disparity may influence this result. A reevaluation is necessary to study the advantages of the 5-year use of tamoxifen in the Japanese racial subgroup.  相似文献   
58.
目的:探讨子宫内膜癌的疗效从其预后因素。方法;收集1979年4月至1991年4月随访资料完整的182例子宫内膜癌。全组病人均经手术及术前放疗,部分病人术后放疗。经统计学X2检验分析预后。结果:总5年生存率80.2%,Ⅰ期91.9%,Ⅱ期81%,Ⅲ期56%,Ⅳ期0,临床分期、病理类型、组织学分级、宫体肌层浸润盆腔淋巴结转移是影响预后的重要因素、结论;术前分段诊刮至关重要、放宽1期病例下术指征是提高Ⅰ期盆腔淋巴结转移病例存活率的关键,术前术后放疗是防止复发提高存活率的有效措施。  相似文献   
59.
During the past two decades many different treatment regimens of combination chemotherapy have been applied in extensive stage small-cell lung cancer (SCLC). This study was carried out to identify whether these modifications have resulted in an improved overall survival for extensive stage during the past two decades. In total, 1111 patients with extensive stage SCLC were included in six consecutive randomised trials in our setting from 1973 until 1992. Of these, 526 patients treated in the early period (1973–1981) were compared with 585 patients treated in the late period (1981–1992) with respect to pretreatment prognostic factors, staging, treatment and outcome. No change in the distribution of prognostic factors was detected and the frequency of patients with extensive stage was equal in the two periods, and no difference in overall response rates and survival was observed (P=0.49). Median survival in the two periods was 208 days and 215 days, respectively. No stage migration or treatment-related improved outcome was observed in extensive disease. We suggest restricting aggressive treatment to patients with favorable prognosis and long-term survival as a realistic aim.  相似文献   
60.
BACKGROUND: Because of their lack of long-term viability, adrenal tissue transplants have shown limited success in alleviating the motor disturbances associated with experimental and pathologic striatal dopamine denervation. In this study, we examined how the graft placement site influences adrenal medulla transplant survival and its relation with the reduction of motor deficits in rats bearing unilateral 6-OHDA lesion. METHODS: One or 5 microL of fetal adrenal medullar tissue was grafted either inside the striatal parenchyma or into the lateral ventricle in contact with the dopamine-denervated striatum. Motor disturbances, as assessed by apomorphine-induced rotation, were correlated to the graft morphologic survival features. RESULTS: Apomorphine-induced rotation showed a marginal reduction of 11% in all groups independently of graft survival features or placement site. Intrastriatal transplants showed limited viability characterized by a substantial loss of graft initial volume as well as fewer and smaller chromaffin cells compared to ventricular grafts, which had a reduced loss of graft initial volume and more and larger chromaffin cells. CONCLUSIONS: Although the lateral ventricle may favor adrenal medulla transplant viability, their induced motor outcome is comparable to that induced by less viable intrastriatal grafts, suggesting that the implanted dopamine-producing cells may interact and influence striatal neurons better when placed in close proximity.  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