全文获取类型
收费全文 | 2432篇 |
免费 | 80篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 40篇 |
妇产科学 | 15篇 |
基础医学 | 274篇 |
口腔科学 | 54篇 |
临床医学 | 179篇 |
内科学 | 510篇 |
皮肤病学 | 23篇 |
神经病学 | 245篇 |
特种医学 | 268篇 |
外科学 | 399篇 |
综合类 | 14篇 |
预防医学 | 65篇 |
眼科学 | 41篇 |
药学 | 185篇 |
中国医学 | 16篇 |
肿瘤学 | 173篇 |
出版年
2022年 | 20篇 |
2021年 | 24篇 |
2020年 | 18篇 |
2019年 | 23篇 |
2018年 | 31篇 |
2017年 | 31篇 |
2016年 | 41篇 |
2015年 | 35篇 |
2014年 | 49篇 |
2013年 | 66篇 |
2012年 | 103篇 |
2011年 | 113篇 |
2010年 | 72篇 |
2009年 | 66篇 |
2008年 | 97篇 |
2007年 | 107篇 |
2006年 | 105篇 |
2005年 | 124篇 |
2004年 | 118篇 |
2003年 | 97篇 |
2002年 | 93篇 |
2001年 | 85篇 |
2000年 | 71篇 |
1999年 | 79篇 |
1998年 | 26篇 |
1997年 | 24篇 |
1996年 | 31篇 |
1995年 | 29篇 |
1994年 | 15篇 |
1993年 | 21篇 |
1992年 | 75篇 |
1991年 | 59篇 |
1990年 | 54篇 |
1989年 | 65篇 |
1988年 | 51篇 |
1987年 | 54篇 |
1986年 | 36篇 |
1985年 | 41篇 |
1984年 | 25篇 |
1983年 | 24篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1975年 | 13篇 |
1973年 | 12篇 |
1970年 | 20篇 |
1969年 | 17篇 |
1968年 | 18篇 |
1967年 | 11篇 |
排序方式: 共有2520条查询结果,搜索用时 296 毫秒
41.
Circulating growth factor levels are associated with tumorigenesis in neurofibromatosis type 1. 总被引:2,自引:0,他引:2
George A Mashour Pablo Hernáiz Driever Melanie Hartmann Stephanie N Drissel Tingguo Zhang Bianca Scharf Ursula Felderhoff-Müser Sadatoshi Sakuma Reinhard E Friedrich Robert L Martuza Victor Felix Mautner Andreas Kurtz 《Clinical cancer research》2004,10(17):5677-5683
PURPOSE: Neurofibromatosis type 1 (NF1) is characterized by systemic development of neurofibromas. Early clinical diagnosis can be ambiguous, and genetic diagnosis can be prohibitively difficult. Dysregulation of a number of growth factors has been suggested to be a mechanism of pathogenesis. This study was performed to assess the contribution of circulating growth factors for diffuse tumorigenesis and the diagnostic value of circulating growth factor identification in serum. EXPERIMENTAL DESIGN: The growth stimulation of neurofibroma-derived cells by serum from NF1 patients was tested, and serum growth factor levels in a cohort of NF1 patients (n = 39) between the ages of 7 and 70 years were analyzed. RESULTS: Concentrations of midkine (MK) and stem cell factor, but not epidermal growth factor, were substantially increased in serum of NF1 patients when compared with healthy controls. Within the NF1 group, MK levels increased dramatically at puberty from an average of 0.79 ng/mL in patients <18 years to 1.18 ng/mL in patients >18 years old. Stem cell factor and MK concentrations above a defined threshold in serum of NF1 patients are of diagnostic benefit for 96% of patients in the cohort tested. Furthermore, serum from NF1 patients enhanced proliferation of human neurofibroma-derived primary Schwann cells and endothelial cells substantially better than normal serum. CONCLUSIONS: Enhanced circulating growth factor levels contribute to diffuse tumorigenesis in NF1 and may provide the basis for molecular diagnosis. 相似文献
42.
M Hosoya Y Kawasaki M Katayose H Sakuma M Watanabe E Igarashi M Aoyama H Nunoi H Suzuki 《Archives of disease in childhood》2006,91(6):469-472
AIMS: To evaluate the prognostic predictive values of cytochrome c, cytokines, and other laboratory measurements in serum collected during neurological onset in acute encephalopathy with multiple organ failure. METHODS: In addition to general laboratory examinations, the concentrations of cytochrome c (apoptosis marker) and cytokines (inflammatory markers) were measured in serum samples collected at the initial phase in 29 patients with acute encephalopathy. The obtained values were evaluated as predictors for the development of severe encephalopathy. RESULTS: Cytochrome c, tumour necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), soluble TNF-receptor 1 (sTNF-R1), and aspartate aminotransferase (AST) concentrations at the initial phase were high and correlated well with patient outcome. High concentrations of serum cytochrome c (>45 ng/ml), sTNF-R1 (>2000 pg/ml), AST (>58 IU/dl), IL-6 (>60 pg/ml), and TNF-alpha (>15 pg/ml) predicted an unfavourable prognosis (sequelae and death) at 93%, 79%, 82%, 77%, and 60%, respectively. The specificity of those markers was 100%, 89%, 83%, 100%, and 100%, respectively. CONCLUSIONS: Serum cytochrome c is the most sensitive and specific predictor for the development of severe encephalopathy at the initial phase. Results suggest that this marker might be used to guide decisions regarding the start of the initial treatment and further intensive care. 相似文献
43.
44.
45.
46.
47.
Tetsushi Sakuma Sayaka Hosoi Knut Woltjen Ken‐ichi Suzuki Keiko Kashiwagi Housei Wada Hiroshi Ochiai Tatsuo Miyamoto Narudo Kawai Yasunori Sasakura Shinya Matsuura Yasushi Okada Atsuo Kawahara Shigeo Hayashi Takashi Yamamoto 《Genes to cells : devoted to molecular & cellular mechanisms》2013,18(4):315-326
48.
Detection of coronary stenosis and myocardial viability using a single intravenous bolus injection of BR14 总被引:1,自引:0,他引:1
Fisher NG Leong-Poi H Sakuma T Rim SJ Bin JP Kaul S 《Journal of the American College of Cardiology》2002,39(3):523-529
OBJECTIVES: The aim of the study was to determine whether coronary stenosis can be detected and myocardial viability assessed after myocardial infarction from a single venous bolus injection of BR14, a new ultrasound contrast agent. BACKGROUND: BR14 is an ultrasound contrast agent that, like (201)Tl, demonstrates redistribution. Whether this principle can be used to determine myocardial viability is not known. METHODS: Non-critical (n = 6) or flow-limiting (n = 4) stenoses were placed on coronary arteries of 10 open-chest dogs, which then underwent 2 h of coronary occlusion followed by reperfusion through the stenosis. Hyperemia was induced to create flow mismatch in the dogs with non-critical stenosis. Hyperemia was not induced in dogs with reduced resting coronary blood flow. All dogs were given 2 ml of BR14 as a bolus injection and serial images were obtained. Myocardial blood flow (MBF) was measured using radiolabeled microspheres. At the end of the experiment, tissue staining was performed to determine infarct size and topography. RESULTS: Initial images demonstrated flow mismatch between the normal bed and that subtended by the stenosis (during hyperemia in dogs without critical stenosis and during rest in those with reduced resting MBF). The perfusion defect size correlated well with radiolabeled microsphere-derived hypoperfused zone (r = 0.89). Regions within the hypoperfused zone that had not undergone necrosis showed redistribution, whereas the necrotic regions showed a persistent defect, the size of which correlated well with infarct size (r = 0.80). CONCLUSIONS: Because of its ability to redistribute, BR14 can define regions of relative hypoperfusion and also discriminate between infarcted and viable tissue within the hypoperfused zone after a single venous injection. This property lends itself to assessing myocardial perfusion during exercise stress. 相似文献
49.
50.
Inhibitory effect of ceramide on insulin-induced protein kinase Czeta translocation in rat adipocytes 总被引:2,自引:0,他引:2
Miura A Kajita K Ishizawa M Kanoh Y Kawai Y Natsume Y Sakuma H Yamamoto Y Yasuda K Ishizuka T 《Metabolism: clinical and experimental》2003,52(1):19-24
Ceramide has been confirmed to be a signal mediator of apoptosis that is induced by tumor necrosis factor-alpha (TNF-alpha). It has also been reported that ceramide may induce insulin resistance as well as TNF-alpha. We investigated the effect of ceramide on insulin signaling pathways, such as insulin receptor (IR) beta-subunit, insulin receptor substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), and protein kinase Czeta (PKCzeta) in rat adipocytes. We examined insulin-stimulated [(3)H]2-deoxyglucose (2-DOG) uptake in rat adipocytes pretreated with N-hexanoylsphingosine (C(6)-ceramide, 10 to 30 micromol/L). Insulin-induced 2-DOG uptake was significantly reduced by C(6)-ceramide pretreatment. We also examined the effect of various concentrations of C(6)-ceramide pretreatment on insulin-induced autophosphorylation of the IR beta-subunit, tyrosine phosphorylation of IRS-1, enzyme activity of PI3K, and membrane-associated PKCzeta immunoreactivity. Pretreatment with C(6)-ceramide significantly reduced autophosphorylation of the IR beta-subunit, tyrosine phosphorylation of IRS-1, and enzyme activity of PI3K. Moreover, membrane-associated PKCzeta immunoreactivity and immunoprecipitable PKCzeta enzyme activity, downstream of PI3K, were significantly suppressed by C(6)-ceramide pretreatment. These results suggest that ceramide may induce insulin resistance via the suppression of IRS-1-PI3K signaling, and subsequent activation of PKCzeta. 相似文献