全文获取类型
收费全文 | 182篇 |
免费 | 7篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 5篇 |
妇产科学 | 3篇 |
基础医学 | 43篇 |
口腔科学 | 7篇 |
临床医学 | 22篇 |
内科学 | 46篇 |
皮肤病学 | 2篇 |
神经病学 | 8篇 |
特种医学 | 4篇 |
外科学 | 29篇 |
预防医学 | 5篇 |
眼科学 | 1篇 |
药学 | 10篇 |
肿瘤学 | 3篇 |
出版年
2023年 | 2篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 9篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 10篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2003年 | 3篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 6篇 |
1967年 | 3篇 |
1945年 | 2篇 |
1937年 | 1篇 |
1932年 | 4篇 |
1930年 | 1篇 |
1925年 | 1篇 |
1919年 | 1篇 |
1912年 | 1篇 |
排序方式: 共有189条查询结果,搜索用时 31 毫秒
1.
R W Landymore A E Marble 《European journal of cardio-thoracic surgery》1989,3(3):203-7; discussion 207-8
Electrical activity was monitored with specially designed plunge electrodes in 19 animals undergoing 3 h of cardioplegic arrest. Electrical activity was recorded on electromagnetic tape and intramyocardial voltage was monitored with an inline voltmeter. Haemodynamic function was assessed before bypass and following 3 h of ischaemia and 45 min of reperfusion. Intramyocardial voltage during normothermic fibrillation measured 2.4 +/- 0.4 mv. Infusion of cardioplegia initiated a complete electrical arrest in all animals and reduced intramyocardial voltage to 33 +/- 7 mu v. Small amplitude electrical activity was present in 9 of 19 animals. Intramyocardial voltage increased to 108 +/- 12 mu v with the onset of small amplitude electrical activity and spectral analysis of the wave form indicated that the fundamental frequency was in the range of 3.08 Hz. Small amplitude electrical activity during cardioplegic arrest was associated with significant post-arrest depression of left ventricular function. Our data confirms that the presence of small amplitude electrical activity impairs myocardial functional recovery and suggests that continuous intramyocardial voltage monitoring may be used to guide the administration of cardioplegia during cardioplegic arrest. 相似文献
2.
M. A. Helal K. C. Watts A. E. Marble 《Medical & biological engineering & computing》1993,31(6):562-568
A hydrodynamic model for the part of the human arterial network below the renal arteries has been constructed using specially
fabricated distensible tubes and a pulsatile pump to simulate an aortoiliac bypass. The experiments and the computer model
indicated that no ‘steal’ occurred due to the insertion of the bypass graft. Also, the results showed that the length of the
stenosis had a non-systematic apparent effect on the physiological significance of the obstruction and that the kinetic power
represented only a small percentage of the total power. The total power efficiency of the bypass graft was unaffected by its
elastic properties. The experimental investigation also indicated that the pressure drop across the stenosis was considerably
larger than the drop calculated using the Poiseuille flow relationship when the stenosis was severe. Therefore, a critical
arterial stenosis value cannot be defined as an obstruction of a constant percentage reduction of luminal area. It varies
directly with the effective cross-sectional area and inversely with the flow rate. The value of angiography in assessing the
functional significance of any arterial stenosis is there-fore limited. A better method for evaluation requires quantitative
measurements of local blood pressure and blood flow, not only at rest, but also under conditions creating augmented flows
due to exercise. 相似文献
3.
Angioplasty Guidewire Velocity: A New Simple Method to Calculate Absolute Coronary Blood Velocity and Flow 总被引:5,自引:0,他引:5
C.Michael Gibson MD J.Theodore Dodge Jr MD Mukesh Goel MD Eyas N Al-Mousa MD Michael Rizzo BS Christine McLean BS Kathryn Ryan BS Anthony Sparano BS Susan J Marble MS William L Daley MD Christopher P Cannon MD Elliott M Antman MD 《The American journal of cardiology》1997,80(12):272-1539
The Thrombolysis In Myocardial Infarction (TIMI) frame count is a relative index of coronary flow that measures time by counting the number of frames required for dye to travel from the ostium to a standardized coronary landmark in a cineangiogram filmed at a known speed (frames/s). We describe a new method to measure distance along arteries so that absolute velocity (length ÷ time) and absolute flow (area × velocity) may be calculated in patients undergoing percutaneous transluminal coronary angiography (PTCA). After PTCA, the guidewire tip is placed at the coronary landmark and a Kelly clamp is placed on the guidewire where it exits the Y-adapter. The guidewire tip is then withdrawn to the catheter tip and a second Kelly clamp is placed on the wire where it exits the Y-adapter. The distance between the 2 Kelly clamps outside the body is the distance between the catheter tip and the anatomic landmark inside the body. Velocity (cm/s) may be calculated as this distance (cm) ÷ TIMI frame count (frames) × film frame speed (frames/s). Flow (ml/s) may be calculated by multiplying this velocity (cm/s) and the mean cross-sectional lumen area (cm2) along the length of the artery to the TIMI landmark. In 30 patients, velocity increased from 13.9 ± 8.5 cm/s before to 22.8 ± 9.3 cm/s after PTCA (p <0.001). Despite TIMI grade 3 flow both before and after PTCA in 18 patients, velocity actually increased 38%, from 17.0 ± 5.4 to 23.5 ± 9.0 cm/s (p = 0.01). For all 30 patients, flow doubled from 0.6 ± 0.4 ml/s before to 1.2 ± 0.6 ml/s after PTCA (p <0.001). In the 18 patients with TIMI grade 3 flow both before and after PTCA, flow increased 86%, from 0.7 ± 0.3 to 1.3 ± 0.6 ml/s (p = 0.001). Distance along coronary arteries (length) can be simply measured using a PTCA guidewire. This length may be combined with the TIMI frame count to calculate measures of absolute velocity and flow that are sensitive to changes in perfusion. TIMI grade 3 flow is composed of a range of velocities and flows. 相似文献
4.
Kelsea M. Drall Catherine J. Field Andrea M. Haqq Russell J. de Souza Hein M. Tun Nadia P. Morales-Lizcano 《Gut microbes》2020,12(1)
ABSTRACT In Canada and the US, the infant diet is supplemented with vitamin D via supplement drops or formula. Pregnant and nursing mothers often take vitamin D supplements. Since little is known about the impact of this supplementation on infant gut microbiota, we undertook a study to determine the association between maternal and infant vitamin D supplementation, infant gut microbiota composition and Clostridioides difficile colonization in 1,157 mother-infant pairs of the CHILD (Canadian Healthy Infant Longitudinal Development) Cohort Study over 2009–2012. Logistic and MaAsLin regression were employed to assess associations between vitamin D supplementation, and C. difficile colonization, or other gut microbiota, respectively. Sixty-five percent of infants received a vitamin D supplement. Among all infants, infant vitamin D supplementation was associated with a lower abundance of genus Megamonas (q = 0.01) in gut microbiota. Among those exclusively breastfed, maternal prenatal supplementation was associated with lower abundance of Bilophila (q = 0.01) and of Lachnospiraceae (q = 0.02) but higher abundance of Haemophilus (q = 0.02). There were no differences in microbiota composition with vitamin D supplementation among partially and not breastfed infants. Neither infant nor maternal vitamin D supplementation were associated with C. difficile colonization, after adjusting for breastfeeding status and other factors. However, maternal consumption of vitamin-D fortified milk reduced the likelihood of C. difficile colonization in infants (adjustedOR: 0.40, 95% CI: 0.19–0.82). The impact of this compositional difference on later childhood health, especially defense against viral respiratory infection, may go beyond the expected effects of vitamin D supplements and remains to be ascertained. 相似文献
5.
While thrombolytic agents have demonstrated improved mortality over the use of placebo, this has come at the expense of bleeding complications such as intracranial hemorrhage (ICH). Tenecteplase (TNK-tPA) is a novel thrombolytic agent engineered to improve upon the ease of use and safety of alteplase (t-PA). Given its longer half-life, TNK-tPA can be administered as a single bolus. The dosing of TNK-tPA has been weight optimized to enhance both safety and efficacy outcomes. Weight-optimized TNK-tPA dosing requires body weight estimation, which may introduce the potential for medication error. However, data from TNK-tPA clinical trials suggest that body weight estimates can err by up to 20 kg (44 lb) without an increased risk of ICH or death. Furthermore, the results of TNK-tPA clinical trials showed that even at the highest weight-optimized dosage of 50 mg, ICH rates were among the lowest reported in clinical trials of thrombolytics for acute myocardial infarction. In elderly female patients of low body weight, the use of weight-optimized TNK-tPA lowered the risk of ICH compared with the use of t-PA, expanding the potential use of thrombolytics to this high-risk patient population. Tenecteplase has demonstrated clinical equivalence to t-PA, but with a wider therapeutic margin of safety. 相似文献
6.
7.
d'Entremont MI Paulson AT Marble AE 《Medical & biological engineering & computing》2002,40(4):380-387
The object of the paper is to present results that show that impedance spectroscopy is an accurate method of assessing the
condition of muscle tissue. Specimens of muscle tissue were excised from 36 Atlantic salmon and subjected to impedance spectroscopy
measurements made at intervals during an 8h period of ischaemia and necrosis. These measurements were conducted for three
different temperatures and for both the longitudinal and the transverse orientations of the muscle fibres. The specimens were
also subjected to ATP, pH and visco-elastic measurement and analysis to establish the degree of correlation between changes
in these quantities and impedance spectroscopy parameters due to ischaemia. It was concluded that the mean relaxation time,
was the impedance spectroscopy parameter that best described the changes taking place in the muscle tissue during the post-mortem
period, decreasing by 60–76% during the 8h. This was the case for all three temperatures and for both orientations. Furthermore,
the muscle tissue changes due to ischaemia, as reflected in the decrease in the mean relaxation time
, were highly correlated with changes in the tissue ATP, pH and dynamic shear storage modulus G′. 相似文献
8.
Gibson CM Murphy SA Marble SJ McCabe CH Antman EM Cannon CP Braunwald E;Thrombolysis in Myocardial Infarction 《The American journal of cardiology》2001,87(4):450-3, A6
The establishment of patency (Thrombolysis In Myocardial Infarction [TIMI] grade 2 or 3 flow) and/or TIMI grade 3 flow at 60 minutes after thrombolytic administration is both a univariate and multivariate predictor of in-hospital and 30-day mortality, and the odds ratios for mortality are nearly identical for TIMI grade 3 flow at 60 and 90 minutes. Thus, the 60-minute angiographic end point appears to be a valid alternative to that at 90 minutes and may permit earlier decisions regarding post-thrombolytic intervention. 相似文献
9.
10.