全文获取类型
收费全文 | 318篇 |
免费 | 26篇 |
专业分类
儿科学 | 3篇 |
妇产科学 | 8篇 |
基础医学 | 16篇 |
口腔科学 | 8篇 |
临床医学 | 108篇 |
内科学 | 115篇 |
皮肤病学 | 7篇 |
神经病学 | 6篇 |
外科学 | 22篇 |
一般理论 | 9篇 |
预防医学 | 11篇 |
药学 | 29篇 |
肿瘤学 | 2篇 |
出版年
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 13篇 |
2015年 | 16篇 |
2014年 | 9篇 |
2013年 | 13篇 |
2012年 | 5篇 |
2011年 | 1篇 |
2010年 | 15篇 |
2009年 | 16篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 13篇 |
1998年 | 20篇 |
1997年 | 17篇 |
1996年 | 19篇 |
1995年 | 17篇 |
1994年 | 23篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 10篇 |
1989年 | 13篇 |
1988年 | 10篇 |
1987年 | 3篇 |
1986年 | 8篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有344条查询结果,搜索用时 0 毫秒
1.
O to Z Reconstruction of Central Upper Lip Defect 总被引:1,自引:0,他引:1
2.
3.
LI-CHING LYU PhD MPH JEAN H HANKIN DrPH MS RD LUCY Q LIU MPH LYNNE R WILKENS MSPH JAMES H LEE PhD MARC T GOODMAN PhD LAURENCE N KOLONEL MD PhD 《Journal of the American Dietetic Association》1998,98(1):44-48
Objective To develop and test a quantitative food frequency method for administration by telephone.Design A comparison study of telephone and face-to-face interviews was conducted among a representative sample of the five major ethnic groups in Oahu, Hawaii. Two interviews were administered 4 to 6 months apart by trained interviewers using identical questionnaires and color photographs of food items showing three different portion sizes. The order of the interviewing methods was randomly assigned. The questionnaire included 115 food items selected to estimate 80% or more of usual dietary intakes. Frequencies and quantities of each item consumed during the past year were obtained.Subjects/setting Subjects were recruited from the Health Surveillance Program of the Hawaii State Department of Health and consisted of 167 men and 158 women, aged 45 to 74 years, who provided a telephone number. Eighty percent of the face-to-face interviews were conducted in the subjects’ homes and 20% were conducted at the workplace or the University of Hawaii Cancer Research Center, if requested.Statistical analyses The paired t test was used to compare the mean daily intakes obtained by the telephone and face-to-face methods. Agreement was measured by the intraclass correlation coefficient (ICC), Pearson correlation coefficient, and weighted κ statistic.Results The means of energy and each nutrient were slightly higher in the first interview than the second, regardless of the interviewing method. Because of close correspondence among all 3 statistical measures of agreement, only the ICCs are reported. The ICCs ranged from .61 for protein and vitamin A to .69 for dietary cholesterol among men, and from .61 for vitamin C to .74 for saturated fat among women. Agreement was not significantly affected by age, gender, ethnicity, order of interview, or educational level.Applications Telephone interviews to obtain quantitative food frequencies are cost-efficient methods for estimating usual dietary intakes among persons in widely scattered geographic areas. Photographs of the foods in 3 portion sizes mailed in advance help the respondents estimate amounts eaten. J Am Diet Assoc. 1998;98:44-48. 相似文献
4.
The Effects of Perfluorodecanoic Acid on Hepatic Stearoyl-CoenzymeA Desaturase and Mixed Function Oxidase Activities in Rats.VANRAFELGHAM, M. J., AND ANDERSON, M. E. (1988). Fundam. Appl.Toxicol. 11, 503-510. Perfluorodecanoic acid (PFDA) causes adioxin-lilce toxic syndrome and alters the hepatic oleate/stearateratio in rats. The acute toxic effects of a single ip dose (50mg/kg) of PFDA on hepatic stearoyl-CoA desaturase and mixedfunction oxidases were studied in male Fischer-344 rats, 14days after dosing. PFDA causes a marked decrease in food intakein rats, resulting in severe body weight loss with delayed lethality(2-3 weeks after dosing). To distinguish the effects of hypophagiafrom those caused by PFDA, pair-fed control rats were used inaddition to ad libitum-fed controls. Stearoyl-CoA desaturaseactivity, responsible for the conversion of stearoyl-CoA tooleoyl-CoA, was absent in both PFDA dosed rats and their pair-fedcontrols at Day 14. Electron transfer through the desaturasesystem was significantly reduced in PFDA-treated rats only,and in these rats there was a significant reduction in microsomalcytochrome an important component of this electron transfersystem. Pentobarbital sleeping times were significantly prolongedin both the PFDA-dosed and pairfed rats, as compared with thead libitumfed controls. This effect was more pronounced in PFDA-dosedrats. Waking plasma pentobarbital concentration was similarin all treatment groups. Hepatic microsomal cytochrome PASOcontent was unaffected. Aminopyrine N-de-methylase activitywas greatly reduced in PFDA-dosed rats. Although pairfed controlsalso had reduced demethylase activity, it was not as pronouncedas in PFDA-dosed rats, and was probably due to the fasted conditionof these animals. Although the mechanism of action of PFDA isnot known, it is possible that PFDA affects microsomal enzymesby altering the structure and/or function of the membranes inwhich they are located, through effects on lipid metabolism. 相似文献
5.
6.
7.
MARC A. VOS Ph .D. ANTON P.M. GORGELS M.D. GYORGYI C. LIPCSEI M.D. S.H. MARIEKE de GROOT M.S. JET D.M. LEUNISSEN HEIN J.J. WELLENS M.D. 《Journal of cardiovascular electrophysiology》1994,5(9):731-742
Mechanism-Specific Action of Levcromakalim. Introduction: The hypothesis that levcromakalim. a potassium channel (IK-ATP.) activator with antihypertensive properties, has a mechanism-specific antiarrhythmic action against repolarization-dependent ventricular tachycardias (VTs) was tested in dogs. Methods and Results: A low dose of leveromakalim (0.01 mg/kg) was selected, which decreased blood pressure by 25% but had almost no electrophysiologic effect on AV nodal or ventricular conduction or effective refractory period. In dogs with chronic AV block, the antiarrhythmic action of this dose of levcromakalim was evaluated in three models of abnormal impulse formation: (I) dsotalol (2 mg/kg) induced torsades de pointes VT, initiated by early afterdepolarizations (EADs). (2) sustained ouabain-induced VTs, which are dependent on delayed after depolarizations (DADs), and (3) VT occurring 24 hours after left anterior descending coronary artery occlusion, which are likely based on abnormal automaticity. Levcromakalim abolished d-sotalol induced U waves, ventricular ectopic beats, and self-terminating bouts of torsades de pointes. Induction of torsades de pointes by pacing was also completely prevented. The cycle length of the idioventricular rhythm, which was lengthened after d-sotalol from 1490 ± 515 to 1700 ± 610 msec (P < 0.05), remained similar after levcromakalim (1655 ± 580 msec). The QT(U) duration, which was increased after d-sotalol from 410 ± 55 to 550 ± 40 msec (P < 0.05), normalized to 405 ± 70 msec (P < 0.05). Lcvcromakulim did not suppress but rather enhanced ouabain-induced VT by decreasing the cycle length slightly from 315 ± 35 to 290 ± 35 msec (P < 0.05). Pretreatment with a beta Mocker prevented this acceleration in rate. Finally, levcromakalim had no effect on VT 24 hours after infarction. Conclusion: A low dose of levcromakalim has specific antiarrhythmic properties against repolarization-dependent arrhythmias, but it does not affect VTs based on other mechanisms of abnormal impulse formation. 相似文献
8.
This paper reviews the major findings and hypotheses to emerge in the literature concerned with speech prosody. Both production and perception of prosody are considered. Evidence from studies of patients with lateralized left or right hemisphere damage are presented, as well as relevant data from anatomical and functional imaging studies. 相似文献
9.
WOOSUP M. PARK MEHRDAD M.R. AMIRHAMZEH CHAO-XIANG JIA MARK R. BIELEFELD SANTOS E. CABRERIZA MARC L. DICKSTEIN HENRY M. SPOTNITZ 《Pacing and clinical electrophysiology : PACE》1994,17(6):1100-1106
Although the elective induction of cardiac arrest for implantable defibrillator insertion under general anesthesia is widely used, the hemodynamics of recovery of arterial blood pressure after cardiac arrest is not well-defined. Accordingly, the time course of recovery of systolic arterial pressure was studied in seven patients during the repetitive induction of ventricular fibrillation (n = 6) or ventricular flutter (n = 1). The mean number of episodes of cardiac arrest was 7 ± 2, and the mean drop in systolic pressure was 84 ± 16mmHg. The mean recovery time for systolic pressure was 10 ± 6 seconds, the average systolic pressure recovery rate was 13 ± 14 mmHg/sec, and the mean percent systolic pressure recovery was 94%± 9%. A negative logarithmic relation was found to exist between the rate of systolic arterial pressure recovery and the duration of ventricular fibrillation or flutter with a correlation coefficient of 0.68 to 0.97 (P < 0.05) in five of the seven patients. A linear relation between the time for systolic pressure recovery and duration of asystole was also defined. These results are consistent with the view that prolongation of ventricular fibrillation or flutter increases the duration of arterial pressure recovery through a negative effect on left ventricular contractility. Increased understanding of these relations may lead to increased safety of implantable defibrillator insertion. 相似文献
10.
CHRISTOPH KLEIN BRIGITTE ROCKSTROH RUDOLF COHEN PATRICK BERG MARC DRESSEL 《Psychophysiology》1996,33(4):426-433
In a delayed matching-to-sample task, the impact of clear or ambiguous go versus clear no-go signals on the post-imperative negative variation (PINV) was examined in 11 patients with a chronic schizophrenic disorder (DSM-III-R) and in a control group of 13 healthy subjects matched to the patient sample by age, sex, and education. Size and spatial position of a visual S2 had to be matched to one of two visual patterns in the S1 presented 4 s earlier. In 96 trials, the S2 was identical in size with one of the two patterns of S1 (clear matching). These trials varied pseudorandomly, with 60 trials in which the S2 was of intermediate size. On a randomly interspersed additional 48 trials, an S2 differing in color and shape signaled no-go. The electroencephalogram was recorded from Fz, Cz, Pz, F3, F4, C3, C4, P3, and P4. Although groups did not differ in contingent negative variation amplitude the PINV was generally more pronounced in patients than in controls. In both groups, ambiguity of the to-be-matched S2 produced larger PINV amplitudes; the no-go signal elicited only a small PINV. Differential effects of ambiguity and no-go on PINV amplitude and its scalp distribution suggest that “performance” and “action” uncertainty contribute to PINV generation and that thresholds for both effects are reduced in schizophrenics. 相似文献