全文获取类型
收费全文 | 2218篇 |
免费 | 128篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 18篇 |
儿科学 | 82篇 |
妇产科学 | 104篇 |
基础医学 | 176篇 |
口腔科学 | 19篇 |
临床医学 | 239篇 |
内科学 | 484篇 |
皮肤病学 | 79篇 |
神经病学 | 57篇 |
特种医学 | 31篇 |
外科学 | 465篇 |
综合类 | 164篇 |
一般理论 | 1篇 |
预防医学 | 167篇 |
眼科学 | 30篇 |
药学 | 194篇 |
肿瘤学 | 44篇 |
出版年
2016年 | 12篇 |
2015年 | 17篇 |
2014年 | 12篇 |
2013年 | 35篇 |
2010年 | 29篇 |
2009年 | 31篇 |
2007年 | 12篇 |
2006年 | 12篇 |
2001年 | 15篇 |
1999年 | 30篇 |
1998年 | 36篇 |
1997年 | 55篇 |
1996年 | 46篇 |
1995年 | 33篇 |
1994年 | 52篇 |
1993年 | 41篇 |
1992年 | 43篇 |
1991年 | 45篇 |
1990年 | 32篇 |
1989年 | 40篇 |
1988年 | 37篇 |
1987年 | 35篇 |
1986年 | 39篇 |
1985年 | 32篇 |
1984年 | 25篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 13篇 |
1980年 | 28篇 |
1979年 | 17篇 |
1978年 | 20篇 |
1977年 | 16篇 |
1976年 | 13篇 |
1971年 | 16篇 |
1970年 | 13篇 |
1965年 | 13篇 |
1964年 | 13篇 |
1963年 | 22篇 |
1962年 | 11篇 |
1961年 | 16篇 |
1960年 | 20篇 |
1959年 | 102篇 |
1958年 | 168篇 |
1957年 | 152篇 |
1956年 | 165篇 |
1955年 | 167篇 |
1954年 | 147篇 |
1949年 | 96篇 |
1948年 | 111篇 |
1946年 | 17篇 |
排序方式: 共有2354条查询结果,搜索用时 15 毫秒
11.
JOHN P. BOURKE LYNNE HOWELL ALAN MURRAY WILLIAM E. HILL J. CAMPBELL COWAN KEVIN BEATT JOAN ERRINCTON STUART JAMESON RONALD G. GOLD 《Pacing and clinical electrophysiology : PACE》1989,12(8):1419-1425
A randomized prospective study was undertaken to compare the electrical performances of three permanent, endocardial, tined pacing leads with different electrode designs--sintered platinum, vitreous carbon, and porous carbon. Ninety-nine patients received one of the leads (S80 31; 423S 32; S100 36). Acute R wave amplitude and ST elevation of the native endocardial electrogram, voltage threshold, impedance, and current flow at four pulse durations (0.25-1.0 msec) were measured. Voltage thresholds were measured noninvasively at each of four pulse durations at 2 days and 1, 3, and 6 months after implantation. No significant differences were found in sensing properties, or current flow at threshold at 0.5 msec pulse duration. The 423S lead had a significantly higher impedance at threshold and both a higher impedance and lower current flow at 5 V. No significant differences in threshold voltages were found between the three leads at any pulse duration, at any of the assessed times after implantation. Six-month thresholds for the S80, 423S, and S100 leads were 1.18 +/- 0.35, 1.17 +/- 0.29, and 1.06 +/- 0.38 V respectively at 0.5 msec pulse duration. Differences between 'high performance' pacing leads need to be of a greater order of magnitude before they can be exploited to give any real clinical advantage to patients. 相似文献
12.
T. J. CAMPBELL 《Internal medicine journal》1996,26(2):147-149
13.
L.A. BROWN M. WISELKA A. CAMPBELL J.H. PRINGLE K. NICHOLSON I. LAUDER 《Histopathology》1991,19(3):225-230
A 47-year-old man with persistent severe oropharyngeal ulceration developed a high-grade T-cell lymphoma soon after commencing treatment with cyclosporin A. Using Southern blotting to identify T-cell beta-chain gene rearrangements, evidence of clonal restriction was found both in blood and lymph node DNA samples. Two BamH1 rearranged bands were demonstrated in both samples. In the blood a 16 Kb band predominated, with a weaker 28 kb band. In the lymph node sample this pattern was reversed. The findings suggest that a bi-clonal population of T-lymphocytes or clonal evolution of an existing T-cell monoclone had developed, and that cyclosporin contributed to the emergence of a high-grade T-cell lymphoma. 相似文献
14.
THOMAS M. JUNG MD PhD RAJ P. TERKONDA MD STEPHEN J. HAINES MD SCOTT STROME MD LAWRENCE J. MARENTETTE MD From the 《Otolaryngology--head and neck surgery》1997,116(6):642-646
The classic approach to anterior skull base lesions uses bifrontal craniotomies together with lateral rhinotomies. This approach requires frontal lobe retraction and is associated with postoperative anosmia and the development of frontal lobe encephalomalacia. The transglabellar/subcranial approach permits removal of anterior skull base lesions without frontal lobe retraction and avoids facial scars. No studies to date, however, have directly compared the two approaches in terms of patient morbidity. The present retrospective study compares the two approaches when used for the removal of anterior skull base lesions in terms of estimated blood loss, number of transfusions, number of days in the hospital and intensive care unit, and postoperative complications. Twenty patients with anterior skull base lesions were examined. The classic approach was used on 10, and the transglabellar/subcranial route was used on 10. When compared with the classic approach, the transglabellar/subcranial approach resulted in a lower estimated blood loss and subsequent transfusion rate, fewer days in the hospital and intensive care unit, and lower numbers and less severe types of complications. Furthermore, visualization of the tumors before resection with the transglabellar/subcranial approach allowed preservation of olfaction in virtually all of these patients. Although this study represents a small sample population, the results are sufficiently impressive to favor the transglabellar/subcranial approach for the removal of a variety of anterior skull base lesions. (Otolaryngol Head Neck Surg 1997;116:642-6.) 相似文献
15.
16.
17.
NUGENT A. M.; McPARLAND J.; McENEANEY D. J.; STEELE I.; CAMPBELL N. P. S.; STANFORD C. F.; NICHOLLS D. P. 《European heart journal》1994,15(3):361-368
Cardiac output was measured in 11 patients undergoing routinecardiac catheterization using a carbon dioxide rebreathing techniqueand compared with cardiac output measured by direct Fick andthermodilution. The carbon dioxide rebreathing technique gaveconsistently lower values for cardiac output than the othertwo methods (mean difference 0·73, 95% CI 0·95to0·511. min1 with the direct Fick and0·72. 95% CI 1·19 to 0·261.min1 with thermodilution). The direct Fick and thermodilutionmethods gave similar results (mean dtfference 0·08,95% CI 0·32 to 0·16a. min1). Cardiacoutput was also measured in 10 healthy subjects at rest andduring two steady-state levels of exercise using the carbondioxide rebreathing technique. Measurements were made in triplicateon 3 separate days. The technique gave reproducible resultsbetween replicates at rest (coefficient of variation 91%) andbecame more reproducible on exercise (coefficients of variation56% and 54% respectively at each exercise level). There wasa good correlation between cardiac output and oxygen consumption(r=0·98 The carbon dioxide rebreathing technique is afeasible non-invasive way of measuring cardiac output. It tendsto underestimate cardiac output at rest but is reproducibleand becomes more so on exercise which is where it should beof most value. 相似文献
18.
19.
20.