全文获取类型
收费全文 | 1492篇 |
免费 | 88篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 67篇 |
妇产科学 | 30篇 |
基础医学 | 148篇 |
口腔科学 | 25篇 |
临床医学 | 120篇 |
内科学 | 286篇 |
皮肤病学 | 7篇 |
神经病学 | 64篇 |
特种医学 | 344篇 |
外科学 | 191篇 |
综合类 | 35篇 |
预防医学 | 115篇 |
眼科学 | 8篇 |
药学 | 92篇 |
中国医学 | 2篇 |
肿瘤学 | 68篇 |
出版年
2021年 | 21篇 |
2020年 | 8篇 |
2018年 | 25篇 |
2017年 | 8篇 |
2016年 | 17篇 |
2015年 | 16篇 |
2014年 | 26篇 |
2013年 | 38篇 |
2012年 | 33篇 |
2011年 | 36篇 |
2010年 | 24篇 |
2009年 | 37篇 |
2008年 | 39篇 |
2007年 | 63篇 |
2006年 | 32篇 |
2005年 | 36篇 |
2004年 | 36篇 |
2003年 | 27篇 |
2002年 | 41篇 |
2001年 | 33篇 |
2000年 | 21篇 |
1999年 | 25篇 |
1998年 | 47篇 |
1997年 | 43篇 |
1996年 | 64篇 |
1995年 | 45篇 |
1994年 | 34篇 |
1993年 | 43篇 |
1992年 | 20篇 |
1991年 | 18篇 |
1990年 | 18篇 |
1989年 | 46篇 |
1988年 | 50篇 |
1987年 | 48篇 |
1986年 | 34篇 |
1985年 | 59篇 |
1984年 | 32篇 |
1983年 | 39篇 |
1982年 | 38篇 |
1981年 | 29篇 |
1980年 | 13篇 |
1979年 | 17篇 |
1978年 | 18篇 |
1977年 | 30篇 |
1976年 | 31篇 |
1975年 | 23篇 |
1974年 | 21篇 |
1973年 | 9篇 |
1970年 | 13篇 |
1966年 | 10篇 |
排序方式: 共有1606条查询结果,搜索用时 15 毫秒
51.
52.
Surface shield: device to reduce personnel radiation exposure 总被引:2,自引:0,他引:2
Young AT; Morin RL; Hunter DW; Nelson KL; Cardella JF; Castaneda-Zuniga WR; Amplatz K 《Radiology》1986,159(3):801-803
A simple device is described that can reduce personnel exposure from scatter radiation by up to 75%. The device consists of an oblong piece of shielding (0.75-mm lead equivalent) that is taped to the side of the patient during percutaneous renal stone removal and other interventional procedures. Contrary to other shields and barriers, this does not interfere with access to the patient. Scatter exposure data from phantom studies are presented and the rationale for surface shielding discussed. 相似文献
53.
In vitro and in vivo investigation of matrix metalloproteinase expression in metastatic tumor models
INTRODUCTION: Overexpression of matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9, has been correlated with poor prognosis in several cancer types including lung, colon and breast. Noninvasive detection of MMP expression might allow physicians to better determine when more aggressive cancer therapy is appropriate. The peptide CTT (CTTHWGFTLC) was identified as a selective inhibitor of MMP-2/9 that inhibits the growth of MDA-MB-435 human breast cancer xenografts. METHODS: CTT was conjugated with the bifunctional chelator DOTA (1,4,7,10-tetraazacyclotetradecane-N,N',N',N'-tetraacetic acid) for radiolabeling with (64)Cu (t(1/2)=12.7 h, 17.4% beta(+), 39% beta(-)), a radionuclide suitable for positron emission tomography (PET). In vitro affinity was determined in a fluorogenic substrate assay. Tumor gelatinase targeting was evaluated in both biodistribution and microPET imaging studies. RESULTS: Cu(II)-DOTA-CTT inhibited hMMP-2 (EC(50)=8.7 microM) and mMMP-9 (EC(50)=18.2 microM) with similar affinity to CTT (hMMP-2 EC(50)=13.2 microM; mMMP-9 EC(50)=11.0 microM). In biodistribution and microPET imaging studies, (64)Cu-DOTA-CTT was taken up by MMP-2/9-positive B16F10 murine melanoma tumors. Subsequently, imaging studies using (64)Cu-DOTA-CTT were performed on MDA-MB-435 tumor-bearing mice. With zymography, tumor MMP-2/9 expression in this model was shown to be inconsistent, resulting in microPET detection of the MDA-MB-435 tumor in only 1 of 24 imaged mice. Following limited imaging success, (64)Cu-DOTA-CTT was shown to have poor in vivo stability. CONCLUSIONS: Despite some evidence for selective uptake of (64)Cu-DOTA-CTT by gelatinase-expressing tumors, the low affinity for MMP-2 and MMP-9 and in vivo instability make this an inadequate radioligand for in vivo tumor evaluation. 相似文献
54.
Sclerosing cholangitis: CT findings 总被引:5,自引:0,他引:5
The value of computed tomography (CT) in the detection of primary sclerosing cholangitis (PSC) in the intrahepatic and extrahepatic biliary systems was assessed by comparing CT scans of 20 cases of PSC with cholangiographic findings. In 16 of 19 cases of extrahepatic duct disease demonstrated with cholangiography, CT demonstrated abnormalities of the common hepatic duct, or bile duct, including duct stenosis, mural nodularity, duct dilatation, wall thickening, and mural enhancement. CT demonstrated intrahepatic disease in all 20 cases, including duct dilatation, duct stenosis, pruning, and beading. CT was superior to cholangiography in characterization of the status of the intrahepatic duct system in 11 of 20 cases. In addition, CT demonstrated extrabiliary complications of PSC in 12 cases and superimposed cholangiocarcinoma in three cases. While cholangiography remains the standard for diagnosis and follow-up of PSC, CT can provide valuable information about the extent and complications of the disease. 相似文献
55.
ER Brown KA Charles SA Hoare RL Rye DI Jodrell RE Aird R Vora U Prabhakar M Nakada RE Corringham M DeWitte C Sturgeon D Propper FR Balkwill JF Smyth 《Annals of oncology》2008,19(7):1340-1346
BACKGROUND: Tumour necrosis factor-alpha (TNF-alpha) is an important regulator of the chronic inflammation contributing to tumour progression. Infliximab, an anti-TNF-alpha monoclonal antibody was investigated in this trial of patients with advanced cancer. The primary objectives were to determine the safety profile and biological response of infliximab in a cancer population. Clinical response was a secondary objective. PATIENTS AND METHODS: Forty-one patients received infliximab at 5 mg/kg (n = 21) or 10 mg/kg (n = 20) i.v. at 0 and 2 weeks and then every 4 weeks. Post-treatment samples were measured for changes in plasma and serum TNF-alpha, CCL2, IL-6 and C-reactive protein (CRP). RESULTS: Infliximab was well tolerated with no dose-limiting toxic effects. At both doses of infliximab, neutralisation of serum TNF-alpha was observed after 1 h while plasma CCL2, IL-6 and serum CRP were decreased 24 and 48 h following infliximab administration. Seven patients experienced disease stablisation (range 10-50+ weeks). There was no evidence of disease acceleration in any patient. CONCLUSIONS: Infliximab treatment was safe and well tolerated in patients with advanced cancer. There was evidence of biological activity with baseline TNF-alpha and CCL2 being correlated with infliximab response. 相似文献
56.
57.
58.
Thigh pain is a serious condition in childhood and should be promptly and thoroughly investigated. Twenty-five cases of thigh
pain lasting between 1 day and 7 months with mid-femoral periosteal thickening were analysed. There were 10 patients with
Ewing's sarcoma, 7 with eosinophilic granuloma, 1 with osteoid osteoma, 1 with leukaemia, 3 with osteomyelitis, 1 with myositis
and 2 with post-traumatic periosteal reaction. It was shown that patients with Ewing's sarcoma and eosinophilic granuloma
have certain patterns of X-ray changes of high diagnostic value, which allow a proper diagnosis in most cases. 相似文献
59.
Rare earth filters are known to reduce radiation dose in radiological investigations. The present investigation used Er and Sm filters that were selected because of their chemical stability and ability to withstand prolonged exposure to the atmosphere. They were used in a comparison with a conventional aluminium filter in a range of paediatric radiological procedures. Introduction of the filters instead of the conventional filter, resulted in a dose reduction of up to twofold with no discernible deterioration in image quality. 相似文献
60.
A systematic review of economic analyses of low-molecular-weight heparin for the treatment of venous thromboembolism 总被引:1,自引:0,他引:1
INTRODUCTION: Public concerns about the increase in health care expenditure have prompted investigators to analyze the costs and benefits of health care interventions. We conducted a systematic review of economic analyses of venous thromboembolism treatment focusing on studies evaluating low-molecular-weight heparin. MATERIALS AND METHODS: We identified studies by a MEDLINE search and a review of bibliographies of retrieved articles. From each eligible study, we extracted data on the study characteristics, the effectiveness, and the cost of managing the venous thromboembolism with respect to treatment. We critically appraised the studies according to the framework from the Users' Guides to the Medical Literature XIII: How to Use an Article on Economic Analysis of Clinical Practice. RESULTS: Six of these eight economic analyses of venous thromboembolism treatment that met the inclusion criteria for this review showed that low-molecular-weight heparin is associated with less recurrent venous thromboembolism and is less costly than treatment with unfractionated heparin. Although discrete recurrent venous thromboembolism event rates were not included in the seventh study, these investigators concluded that the cost of low-molecular-weight heparin for the treatment of venous thromboembolism treatment was offset by the savings associated with fewer hospital admissions when low-molecular-weight heparin was used. In the eighth study, although the cost of treatment with low-molecular-weight heparin was higher than treatment with unfractionated heparin, the investigators concluded that low-molecular-weight heparin is cost-effective for inpatient management. CONCLUSIONS: Low-molecular-weight heparin treatment may confer economic advantages over unfractionated heparin therapy because it does not require anticoagulant monitoring and it facilitates outpatient therapy. 相似文献