全文获取类型
收费全文 | 867篇 |
免费 | 53篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 67篇 |
妇产科学 | 8篇 |
基础医学 | 86篇 |
口腔科学 | 81篇 |
临床医学 | 78篇 |
内科学 | 176篇 |
皮肤病学 | 13篇 |
神经病学 | 12篇 |
特种医学 | 223篇 |
外科学 | 55篇 |
综合类 | 16篇 |
预防医学 | 25篇 |
眼科学 | 15篇 |
药学 | 25篇 |
肿瘤学 | 42篇 |
出版年
2023年 | 4篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 10篇 |
2016年 | 14篇 |
2015年 | 15篇 |
2014年 | 22篇 |
2013年 | 20篇 |
2012年 | 21篇 |
2011年 | 18篇 |
2010年 | 33篇 |
2009年 | 29篇 |
2008年 | 14篇 |
2007年 | 27篇 |
2006年 | 11篇 |
2005年 | 15篇 |
2004年 | 14篇 |
2003年 | 10篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 47篇 |
1997年 | 56篇 |
1996年 | 52篇 |
1995年 | 48篇 |
1994年 | 47篇 |
1993年 | 30篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 25篇 |
1988年 | 31篇 |
1987年 | 14篇 |
1986年 | 32篇 |
1985年 | 28篇 |
1984年 | 14篇 |
1983年 | 18篇 |
1982年 | 18篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1978年 | 7篇 |
1977年 | 13篇 |
1976年 | 16篇 |
1975年 | 4篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有926条查询结果,搜索用时 26 毫秒
1.
J.A. Hannam S.J. Mitchell D. Cumin C. Frampton A.F. Merry M.R. Moore C.J. Kruger 《British journal of anaesthesia》2019,122(2):198-205
Background
Etomidate is frequently selected over propofol for induction of anaesthesia because of a putatively favourable haemodynamic profile, but data confirming this perception are limited.Methods
Patients undergoing cardiac surgery were randomised to induction of anaesthesia with propofol or etomidate. Phase I (n=75) was conducted as open-label, whereas Phase II (n=75) was double blind. Mean arterial blood pressure (MAP) and boluses of vasopressor administered after induction were recorded. The primary endpoint was the area under the curve below baseline MAP (MAP-time integral) during the 10 min after induction. Secondary endpoints were the use of vasopressors over the same period, and the effect of blinding on the aforementioned endpoints. Groups were compared using regression models with phase and anaesthetist as factors.Results
The mean difference between etomidate and propofol in the MAP-time integral below baseline was 2244 mm Hg s (95% confidence interval, 581–3906; P=0.009), representing a 34% greater reduction with propofol. Overall, vasopressors were used in 10/75 patients in the etomidate group vs 21/75 in the propofol group (P=0.38), and in 20/74 patients during the blinded phase vs 11/76 during the open-label phase (P=0.31). The interaction between randomisation and phase (open-labelled or blinded) was not significant for either primary (P=0.73) or secondary endpoints (P=0.90).Conclusions
Propofol caused a 34% greater reduction in MAP-time integral from baseline after induction of anaesthesia than etomidate, despite more frequent use of vasopressors with propofol, confirming the superior haemodynamic profile of etomidate in this context. The proportion of patients receiving vasopressors increased slightly, albeit not significantly, in both groups in the blinded phase.Clinical trial registration
Australian and New Zealand Clinical Trials Registry, ACTRN12614000717651. 相似文献2.
3.
Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
4.
5.
6.
Ralls PW; Johnson MB; Kanel G; Dobalian DM; Colletti PM; Boswell WD Jr; Radin DR; Halls JM 《Radiology》1986,161(2):451-454
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease. 相似文献
7.
Objective . To describe the importance of migraine in Santiago, Chile, by analyzing its prevalence, clinical features and impact by age, gender and socioeconomic status. Methods . In 1993, a representative sample of 1,540 adults of the province of Santiago were interviewed using a standard questionnaire. A total of 1,385 (89.9%) subjects responded to the survey. Initially, a designated member of each household responded to the questionnaire. Subsequently, each household member with headaches was asked to respond to questions about severity, frequency, location, duration, associated symptoms and impact in work and social activities of their most frequent headaches. Migraine diagnoses were determined in accordance with the International Headache Society (IHS) criteria of 1988. Results. Recurrent headaches in the past year were found in 516 (36.82%) respondents, 145 (28.1%) males and 371 (71.9%) females. Total prevalence of migraine was found to be 7.3% (95%, CI 5.9–8.6); 11.9% (95% CI 9.6–14.2) in females and 2.0% (95% CI 0.9–3.0) in males. Overall, migraine constituted 19.6% (101/516) of all headaches reported in this sample. The prevalence did not vary significantly by age groups or socioeconomic status (SES). Migraine with aura had an overall prevalence of 3.5% (CI 0.8–7.1), and was significantly more frequent in females. In 60–70% of cases the attacks lasted 2–6 h and the frequency was 3.3 and 3.4 per month in females and males respectively. Both males and females reported significantly high percentages of attacks during work. Conclusions . Migraine prevalence in a sample of adults of Santiago is similar to that reported in previous studies using IHS criteria. Women of all socioeconomic levels are at an increased risk. 相似文献
8.
9.
10.