全文获取类型
收费全文 | 719篇 |
免费 | 21篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 17篇 |
妇产科学 | 28篇 |
基础医学 | 81篇 |
口腔科学 | 13篇 |
临床医学 | 60篇 |
内科学 | 140篇 |
皮肤病学 | 35篇 |
神经病学 | 25篇 |
特种医学 | 28篇 |
外科学 | 81篇 |
综合类 | 30篇 |
一般理论 | 1篇 |
预防医学 | 65篇 |
眼科学 | 6篇 |
药学 | 85篇 |
肿瘤学 | 34篇 |
出版年
2013年 | 6篇 |
2012年 | 3篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 25篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 18篇 |
1992年 | 13篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 15篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1965年 | 4篇 |
1964年 | 4篇 |
1963年 | 9篇 |
1962年 | 2篇 |
1961年 | 4篇 |
1960年 | 9篇 |
1959年 | 36篇 |
1958年 | 63篇 |
1957年 | 58篇 |
1956年 | 64篇 |
1955年 | 56篇 |
1954年 | 38篇 |
1950年 | 3篇 |
1949年 | 26篇 |
1948年 | 48篇 |
1946年 | 9篇 |
1927年 | 2篇 |
排序方式: 共有740条查询结果,搜索用时 15 毫秒
51.
A. D. STEWART A. L. CALDER J. M. NEUTZE A. H. JAMES P. W. T. BRANDT 《Journal of paediatrics and child health》1992,28(2):192-195
Two patients with Down syndrome, intracardiac communications and elevated pulmonary arteriolar resistance presented early in life. Both patients had significant stenosis of pulmonary veins. The progressive nature of the stenosis is illustrated in one patient. Pulmonary venous stenosis in Down syndrome has been recorded only twice before in the literature, and may play a part in the early onset of pulmonary vascular occlusive disease in some patients. 相似文献
52.
53.
Parental history of hypertension and enhanced cardiovascular reactivity are associated with decreased pain ratings 总被引:2,自引:0,他引:2
Ischemic pain was examined in adult males with and without a parental history of hypertension. Blood pressure and heart rate were recorded during baseline, cold pressor, and ischemia. Repeated pain ratings were obtained during cold pressor and ischemia, and the McGill Pain Questionnaire was completed after each stressor. A median split was used to identify high and low mean arterial pressure and heart rate reactors to cold pressor. Parental history of hypertension, high heart rate reactivity, and high mean arterial pressure reactivity were each associated with significantly lower ischemic pain ratings on the McGill Pain Questionnaire, suggesting that risk for hypertension is associated with hypoalgesia in normotensives. 相似文献
54.
GRAHAM R. STEWART LYNNE ELSON EDMUNDO ARAUJO RONALD GUDERIAN THOMAS B. NUTMAN JANETTE E. BRADLEY 《Parasite immunology》1995,17(7):371-380
Isotypejsubclass-specific antibody responses to adult Onchocerca volvulus extract (OvAg) were assessed by both ELISA and immunoblotting for a group of putatively immune individuals (PIs, n = 29) from a hyperendemic area in Ecuador and for a group of infected individuals (INFs, n = 47) from the same region. As a group, the Pis have been previously shown to possess lower levels of OvAg specific IgG1, IgG2, IgG3 and IgG4 than INFs but semiquantitative analysis revealed that the relative proportions of these subclasses differs between the two groups. The IgG of the PI group contained a higher proportion of IgG3 and a lower proportion of IgG4 than the INF group. The frequency distribution of IgG3 responses was similar for the PI and INF groups. The frequency distributions for IgG1, IgG4 and IgE were significantly different between the PI and INF groups. A subgroup of the Pis were identified from frequency distributions and multivariate plots of individual isotype responses as having antibody responses (mainly IgG4) possibly indicative of cryptic infection. High IgE responses were exclusive to INF individuals, and a rare response type of high IgG3 with negligible levels of other isotypes/subclasses was seen only in the PI group. However, the majority of the Pis had negligible responses for all antibody classes. Immunoblots demonstrated no obvious differences in qualitative recognition between the PIs and INFs. 相似文献
55.
Magnesium sulfate neither potentiates nor inhibits tissue plasminogen activator-induced thrombolysis
D. STEWART V. J. MARDER† S. STARKMAN†‡ J. L. SAVER‡ 《Journal of thrombosis and haemostasis》2006,4(7):1575-1579
BACKGROUND: Increasing circulating magnesium concentrations to 2-fold over normal baseline may afford a neuroprotective effect in patients with acute cerebral ischemia. OBJECTIVES: As patients receiving magnesium sulfate (MgSO(4)) in human clinical trials may also be candidates for subsequent thrombolytic therapy with tissue plasminogen activator (t-PA), preclinical assessment of possible inhibition or potentiation of fibrinolytic activity by MgSO(4) has important clinical relevance. METHODS: We utilized an in vitro system, in which D-dimer release served as a reflection of t-PA-induced clot lysis, to measure the effect of magnesium at the target concentration being tested in human stroke clinical trials, and at 2- and 3-fold higher levels. Clots from normal volunteers were exposed to t-PA at concentrations that correspond to therapeutic or endogenous plasma t-PA levels. RESULTS: MgSO(4) had no effect on t-PA-induced clot lysis at up to 3-fold target magnesium concentration (6x normal serum concentration). CONCLUSIONS: MgSO(4) concentrations well above the targeted level in therapeutic stroke trials does not affect t-PA-induced fibrinolytic activity, and therefore is a suitable agent for trials of combined neuroprotective and thrombolytic therapy in patients with acute ischemic stroke. 相似文献
56.
Reduced platelet glutathione peroxidase activity and serum selenium concentration in atopic asthmatic patients 总被引:3,自引:0,他引:3
N. L. A. MISSO K. A. POWERS R. L. GILLON G. A. STEWART P. J. THOMPSON 《Clinical and experimental allergy》1996,26(7):838-847
Background Asthmatic inflammation results in increased oxygen free radical generation and assessment of the activity of the selenitim (Se) dependent anti-oxidant enzyme, glutathione peroxidase (GSH-Px) in asthma may therefore be important. Objective To test the hypothesis that reduced GSH-Px activity and Se intake contribute to asthmatic infiammation, platelet and whole blood GSH-Px activities and serum and whole blood Se concentrations were measured and compared in atopic and non-atopic asthmatic patients and non-asthmatic control subjects. Methods GSH-Px activities of whole blood and isolated platelets were assessed in 41 asthmatic patients (33 atopic) and 41 age- and sex-matched non-asthmatic sttbjects (15 atopic) by spectrophotometric assay based oti the oxidation of NADPH. Se concentrations were determined by semi-automated fluorimetric assay. Results Mean (± sd) platelet GSH-Px activity was lower in asthmatic (89.5 ± 45.7 μmol NADPH oxidized min?1 g?1 of protein) than in non-asthmatic subjects (109,9 ± 41.9; P= 0.038) and in atopic (89.7 ± 45.1, n = 48) compared with non-atopie subiects (113.7 ± 40.9, n= 34: P= 0.016). Mean whole blood GSH-Px activity was also lower in atopic (12.2 ± 5.2 μmol NADPH oxidized min?1 g?1 of Hb) than in non-atopic subjects (14.5 ± 4.2; P= 0.038). In non-asthmatic subjects, the mean whole blood GSH-Px activity was lower in men (9.9 ± 3.5) than in women (14.5 ± 3.7; P = 0.0004) and was positively correlated with age (r= 0.51; P = 0.0006). Mean serum Se was lower in asthmatic (1.07 ± 0.12 μmol/L) than in non-asthmatic subjects (1.16 ± 0.31; P = 0.036), Using multiple linear regression, asthma was an independent predictor of decreased platelet GSH-Px after gender, age and serum Se were taken into account (P = 0.048) while atopy was a significant predictor of low whole blood GSH-Px independent of asthma, gender, age and whole blood Se (P = 0.033). Conclusions In addition to Se status, atopy, gender and uge all appear to influence GSH-Px activity, although the relative importance of these factors may difler in asthmatic and non-asthmatic populations. It seems likely that the reduced activity of this enzyme in platelets und hiood may reflect mechanisms associated with the pathogenesis and severity of asthma. 相似文献
57.
Comparison of high and low doses of suxamethonium 总被引:2,自引:0,他引:2
In a double-blind study, 67 young adult patients undergoing anaesthesia for dental extractions were allocated at random to receive either 0.5 mg/kg or 1.5 mg/kg suxamethonium. A greater increase in arterial pressure was seen following induction in the 1.5 mg/kg group, although overall intubating conditions were similar in the two groups. Suxamethonium-associated muscle pains were significantly more common in the group which received the larger dose (p less than 0.05). 相似文献
58.
Pagetoid Reticulosis 总被引:2,自引:0,他引:2
Two patients with solitary lesions of pagetoid reticulosis are presented. A third case with disseminated lesions and similar microscopic detail is also reported. Lighg microscopic findings include an abnornal cell infiltrate confined to the epidermis and distributed diffusely in a pagetoid pattern. In ultrathin sections, the abnormal cells are seen to have an abundant cytoplasm with numerous organelles and a convoluted nucleus, often with a prominent nucleolus. The nature of the abnormal cells is discussed. The infiltrate is differentiated from that of mycosis fungoides. 相似文献
59.
60.