全文获取类型
收费全文 | 2193篇 |
免费 | 175篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 107篇 |
妇产科学 | 45篇 |
基础医学 | 214篇 |
口腔科学 | 26篇 |
临床医学 | 221篇 |
内科学 | 496篇 |
皮肤病学 | 14篇 |
神经病学 | 212篇 |
特种医学 | 214篇 |
外科学 | 158篇 |
综合类 | 34篇 |
一般理论 | 117篇 |
预防医学 | 233篇 |
眼科学 | 52篇 |
药学 | 122篇 |
1篇 | |
肿瘤学 | 103篇 |
出版年
2023年 | 11篇 |
2022年 | 15篇 |
2021年 | 36篇 |
2020年 | 14篇 |
2019年 | 26篇 |
2018年 | 39篇 |
2017年 | 33篇 |
2016年 | 22篇 |
2015年 | 30篇 |
2014年 | 30篇 |
2013年 | 60篇 |
2012年 | 66篇 |
2011年 | 91篇 |
2010年 | 59篇 |
2009年 | 57篇 |
2008年 | 93篇 |
2007年 | 69篇 |
2006年 | 78篇 |
2005年 | 74篇 |
2004年 | 77篇 |
2003年 | 62篇 |
2002年 | 52篇 |
2001年 | 58篇 |
2000年 | 77篇 |
1999年 | 71篇 |
1998年 | 39篇 |
1997年 | 37篇 |
1996年 | 56篇 |
1995年 | 41篇 |
1994年 | 44篇 |
1993年 | 40篇 |
1992年 | 55篇 |
1991年 | 59篇 |
1990年 | 59篇 |
1989年 | 78篇 |
1988年 | 59篇 |
1987年 | 60篇 |
1986年 | 61篇 |
1985年 | 57篇 |
1984年 | 32篇 |
1983年 | 29篇 |
1982年 | 32篇 |
1981年 | 24篇 |
1980年 | 23篇 |
1979年 | 23篇 |
1977年 | 22篇 |
1976年 | 27篇 |
1975年 | 19篇 |
1967年 | 13篇 |
1966年 | 17篇 |
排序方式: 共有2378条查询结果,搜索用时 15 毫秒
71.
72.
Platelet kinetics in patients with idiopathic thrombocytopenic purpura and moderate thrombocytopenia 总被引:4,自引:2,他引:4
We studied ten normal subjects and 20 patients with stable, untreated idiopathic thrombocytopenic purpura (ITP) and platelet counts in the range of 35,000 to 110,000/microL. The diagnosis was made by clinical criteria. Platelet-associated IgG was increased in all nine of the nine patients studied. Autologous platelets were labeled with chromium 51 and reinfused for measurement of mean cell life and platelet production rate. Mean cell life was calculated by two methods, weighted mean and multiple hit, with excellent agreement between the two. As expected, mean cell life was significantly reduced in ITP patients as compared to the normal subjects (2.9 days v. 8.0 days, P less than .001). However, mean platelet production rates in ITP patients and normal subjects, 3.5 and 3.8 X 10(9) platelets/k/d respectively, were not significantly different. Platelet production rate was above and below the normal range (2 to 5.6 X 10(9) platelets/k/d) in two and four patients, respectively. We conclude that the rate of platelet production is not increased in most patients with ITP who have platelet counts greater than 35,000/microL. We did find that platelet size was increased in eight of the 12 patients in whom it was measured, including two of the patients with low platelet production. 相似文献
73.
Solomon Aragie Sintayehu Gebresillasie Ambahun Chernet Ayalew Shiferaw Zerihun Tadesse Mulat Zerihun Nicole E. Varnado Sun Y. Cotter Dionna M. Wittberg Zhaoxia Zhou Elizabeth Kelly Callahan Scott D. Nash Kristen Aiemjoy Jeremy D. Keenan 《The American journal of tropical medicine and hygiene》2021,104(4):1271
74.
Eshetu Sata Andrew W. Nute Tigist Astale Demelash Gessese Zebene Ayele Mulat Zerihun Ambahun Chernet Berhanu Melak Kimberly A. Jensen Mahteme Haile Taye Zeru Melkamu Beyen Adisu Abebe Dawed Fikre Seife Zerihun Tadesse Elizabeth Kelly Callahan Jeremiah Ngondi Scott D Nash 《The American journal of tropical medicine and hygiene》2021,104(4):1278
75.
76.
The pathogenesis of oxygen toxicity remains unknown but may involve leukocyte mediated injury. The effects of hyperoxia on several lower respiratory tract parameters were examined in bronchoalveolar lavage fluid of normal nonsmoking subjects who inhaled a fractional inspired oxygen concentration of 50 percent (mean exposure: 44 h). Evidence that 50 percent O2 produced oxidative stress in the lung included recovery of fluorescent products of lipid peroxidation and partial oxidation of alpha 1-antitrypsin in BAL fluid obtained after O2 exposure. To examine whether alveolar macrophage-derived leukotriene B4 may be generated in response to 50 percent O2, AM were isolated from O2-exposed subjects and compared with AM recovered from subjects breathing room air. Leukotriene B4 levels were elevated in supernatants from both unstimulated and arachidonic acid-stimulated AM obtained from hyperoxia-exposed subjects. In hyperoxia-exposed individuals, LTB4 levels were also elevated in extracted BAL fluid. The percentage of BAL neutrophils was also significantly increased after O2 exposure (2.8 +/- 0.6 vs 1.2 +/- 0.4 percent, p = 0.05). We conclude that an FIO2 of 50 percent inhaled for 44 h is associated with enhanced oxidative stress, stimulation of AM to release LTB4, and a small but significantly increased percentage of neutrophils recovered in BAL fluid. 相似文献
77.
78.
Sinoaortic baroreceptor denervation is reported to produce exaggerated centrally derived cardiovascular and endocrine responses. We examined the effect of sinoaortic denervation (SAD) on the cardiovascular and endocrine responses to two acute stressors, footshock and immobilization, in male Sprague-Dawley rats. Parameters measured were mean arterial pressure (MAP), heart rate (HR) and plasma levels of oxytocin (OT) and vasopressin (VP). Baseline MAP was elevated in the SAD group (approximately 25 mm Hg) and footshock stress increased arterial pressure equivalently in both groups. This stress caused tachycardia and increased plasma OT, with a tendency for the SAD group to show blunted responses. Immobilization increased HR but caused no change in MAP and no significant difference between the groups. This form of stress also increased plasma OT, and again the SAD group showed a diminished response. Plasma VP was not significantly altered by either stressor. The results of these studies indicate that SAD does not uniformly increase the cardiovascular and endocrine responses to all stressors or centrally derived stimuli. These results also suggest that the lack of an increase in plasma VP is not related to baroreceptor-mediated inhibition of secretion under stressful conditions. 相似文献
79.
John A. Callahan Edmund M. Wroblewski Guy S. Reeder William D. Edwards James B. Seward Abdul J. Tajik 《The American journal of cardiology》1982,50(4):762-768
We reviewed the records of the Mayo Clinic patients with known carcinoid syndrome in whom echocardiographic studies had been done. Nineteen patients had M-mode and 2-dimensional echocardiographic examinations, and 1 patient had an M-mode examination only. Of the 20 patients, 8 had no evidence by echocardiogram of carcinoid heart disease; 2 had changes in the tricuspid valve echogram suggestive of early carcinoid heart disease, and the other 10 patients had the following distinctive echocardiographic findings: (1) the pattern of right ventricular volume overload (enlarged right ventricle with abnormal septal motion); (2) abnormal right-sided valves, including (a) a striking appearance of the tricuspid valve, the leaflets appearing thickened, retracted, and fixed in a semiopen position throughout the cardiac cycle, and (b) thickened, retracted pulmonic valve cusps, when visualized; and (3) the left-sided valves and chambers rarely involved. These echocardiographic features are distinctive of advanced carcinoid heart disease and correlate closely with pathologic findings. 相似文献
80.
Oral corticosteroid therapy for patients with stable chronic obstructive pulmonary disease. A meta-analysis. 总被引:9,自引:0,他引:9
PURPOSE: To evaluate the effectiveness of oral corticosteroid therapy in patients with stable chronic obstructive pulmonary disease. DATA IDENTIFICATION: An English-language literature search using MEDLINE (1966 to 1989) and a bibliographic review of all retrieved articles identified 33 original studies of oral corticosteroid use in chronic obstructive pulmonary disease published since 1951. STUDY SELECTION: We submitted a photocopy of each study's "methods" section to three nonstudy physician-investigators who used nine explicit criteria to independently assess study quality. Ten studies met all criteria and five studies met some of the criteria. DATA EXTRACTION: To compare outcomes across all qualifying studies, we defined response to therapy as a 20% or greater increase in the baseline forced expiratory volume in 1 second (FEV1); we defined the treatment effect size for each study as the proportion of patients who responded to corticosteroid therapy minus the proportion of patients who responded to placebo. Potential confounding variables as related to eligibility criteria and treatment protocols were also assessed for each study. RESULTS OF DATA SYNTHESIS: Among ten studies that met all nine criteria, we found no significant differences in eligibility criteria, treatment protocol, or study design. No association was found between treatment effect size and publication date, study size, mean patient age, or FEV1. These studies had reported effect sizes ranging from 0% to 56%; we calculated a weighted mean effect size of 10% (95% CI, 2% to 18%). When studies meeting only some of the criteria were included in the calculation, the weighted mean effect size was 11% (95% CI, 4% to 18%). CONCLUSIONS: Patients with stable chronic obstructive pulmonary disease receiving oral corticosteroid therapy have a 20% or greater improvement in baseline FEV1 approximately 10% more often than similar patients receiving placebo. 相似文献