全文获取类型
收费全文 | 1192篇 |
免费 | 47篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 95篇 |
妇产科学 | 47篇 |
基础医学 | 165篇 |
口腔科学 | 18篇 |
临床医学 | 105篇 |
内科学 | 239篇 |
皮肤病学 | 21篇 |
神经病学 | 109篇 |
特种医学 | 67篇 |
外科学 | 155篇 |
综合类 | 14篇 |
预防医学 | 85篇 |
眼科学 | 16篇 |
药学 | 68篇 |
肿瘤学 | 36篇 |
出版年
2021年 | 15篇 |
2020年 | 14篇 |
2019年 | 15篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 20篇 |
2015年 | 18篇 |
2014年 | 20篇 |
2013年 | 40篇 |
2012年 | 56篇 |
2011年 | 45篇 |
2010年 | 25篇 |
2009年 | 41篇 |
2008年 | 51篇 |
2007年 | 62篇 |
2006年 | 58篇 |
2005年 | 56篇 |
2004年 | 53篇 |
2003年 | 32篇 |
2002年 | 39篇 |
2001年 | 39篇 |
2000年 | 41篇 |
1999年 | 29篇 |
1998年 | 33篇 |
1997年 | 33篇 |
1996年 | 19篇 |
1995年 | 14篇 |
1994年 | 16篇 |
1993年 | 20篇 |
1992年 | 26篇 |
1991年 | 17篇 |
1990年 | 28篇 |
1989年 | 26篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 17篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1976年 | 11篇 |
1975年 | 9篇 |
1972年 | 6篇 |
1971年 | 8篇 |
1970年 | 8篇 |
1969年 | 7篇 |
1967年 | 12篇 |
1966年 | 9篇 |
排序方式: 共有1246条查询结果,搜索用时 31 毫秒
21.
Schwenk A Bürger B Ollenschläger G Stützer H Wessel D Diehl V Schrappe M 《Clinical nutrition (Edinburgh, Scotland)》1994,13(4):212-220
In HIV-infected patients, the outcome of counselling as the first step of a nutritional intervention programme was evaluated, in order to identify clinical and nutritional predictors for its efficacy. 75 HIV-infected patients were investigated, most with advanced disease. Nutritional status was determined by body weight, bioelectrical impedance and 7-day food intake record. Prior mean weight loss was 10% (range = +4% to -31%). Counselling facilitated weight gain in 40 75 patients (1-4 months later, overall mean difference +1.4 +/- 6.2%) and in 14 34 patients (8-11 months later, overall mean difference -1.4 +/- 9.0%). Weight changes correlated with changes in body cell mass (r(2) = .69, p < .001) and in body fat (r(2) = .29, p < 0.05), but not extracellular mass. Underlying conditions such as AIDS definition, fever, and diarrhoea correlated to prior weight loss (p < .001) but not to the outcome of counselling. Low energy intake (before counselling, < 31.5 kcal/kg) did not correlate to prior weight loss but it predicted further weight loss (p < 0.05 towards normal intake). High energy intake (> 38.5 kcal/kg) correlated (p < 0.05) with more prior weight loss but not with further weight changes. Nutritional counselling may be an effective first-line intervention for malnourished HIV infected patients. More than half of patients gain weight without other nutritional treatment. Whereas the severity of malnutrition is influenced by the underlying disease, fever, and diarrhoea, the course of weight change after nutritional intervention is not. Counselling may reduce the nutritional impact of these risk factors. In patients with low spontaneous intake, efficacy of counselling alone is limited, but it may help to identify those who require more invasive nutritional treatment. 相似文献
22.
del Nido PJ Duncan BW Mayer JE Wessel DL LaPierre RA Jonas RA 《The Annals of thoracic surgery》1999,67(1):169-172
BACKGROUND: Repair of anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) in infants carries a high operative risk, particularly in infants with myocardial infarction and poor left ventricular function. The marked recovery of left ventricular function reported late after repair, however, suggests that an aggressive approach to repair should be undertaken. METHODS: Of 31 children undergoing primary repair of ALCAPA at our institution from 1987 to 1996, 26 were infants (6 weeks to 9 months old). All but 2 had severe left ventricular dysfunction, and 8 had moderate to severe mitral regurgitation. Seven children were unable to be weaned from cardiopulmonary bypass because of poor left ventricular function and elevated left atrial pressure. These 7 children were placed on mechanical left ventricular support using a centrifugal pump, with support ranging from 2.2 to 70.6 hours. RESULTS: One child died shortly after the start of left ventricular assist (2.2 hours), and another died of arrhythmia within 24 hours after successful decannulation. All 5 survivors had significant improvement in left ventricular function, with 2 requiring late mitral valve repair. CONCLUSIONS: Infants with ALCAPA who have severe left ventricular dysfunction represent a higher risk group for repair. However, with use of mechanical circulatory support in those unable to be weaned from cardiopulmonary bypass, a high survival rate can be achieved with good long-term recovery. We conclude that an aggressive approach to early repair in all children with ALCAPA is warranted, regardless of the degree of left ventricular dysfunction. 相似文献
23.
Eighty four out of 2151 militancy trauma patients sustained severe maxillofacial injury from Jan 1990 to March 1993. The resuscitation, stabilisation and intensive care of these patients was based on management priorities of primary resuscitation, care of airway, management of haemodynamics, oxygenation and monitoring. Anaesthesia was administered in a situation when the airway was likely to be compromised and the patients were critically sick. Initial ventilation and oxygenation was the most difficult and could be achieved with satisfactory seal around the face mask by applying water-soaked guaze pieces around the mouth and nose to “fill-in” the defects. Tracheal intubation could be accomplished with intravenous sedation by an experienced anaesthesiologist. Dental occlusion and wiring necessiated the placement of nasotracheal tube for 48-72 hours after surgery.KEY WORDS: Trauma, Maxillofacial injury, Trauma anesthesia, Anaesthesia and critical care 相似文献
24.
Summary To demonstrate an as yet merely postulated generalized osteopathy in psoriatics, the serum calcium level, the alkaline phosphatase in the serum and the urinary excretion of hydroxyproline were evaluated in 24 patients with Ps and 24 patients with PA. Moreover, the bone bioptates from 25 patients with PA and 10 patients with Ps were examined histologically and measured morphometrically. The investigations provide evidence for the existence of a generalized latent osteopathy in terms of an elevated bone turnover rate without loss of bone volume (high turnover remodelling) in both patients with PA as well as those with Ps without arthritis. As a pathogenetically essential factor shared by dermatosis and osteopathy, latent vitamin D deficiency and/or D hormone resistance is discussed. 相似文献
25.
OBJECTIVE: Because survival from admission to discharge does not provide parents and physicians information about future life expectancy in the premature neonate, we characterized the actuarial survival, defined as the future life expectancy from a given postnatal age, in a large inborn population of premature infants < 30 weeks' gestation. STUDY DESIGN: We determined daily actuarial survival of 1925 inborn infants (23 to 29 weeks' gestation) admitted to the Baylor Affiliated Nurseries from July 1986 through December 1994, stratified by 100-g birth weight and by 1-week gestational-age intervals. RESULTS: In the 501- to 600-g birth weight stratum, actuarial survival improved from 31% at birth, to 61% on day of life 7, and then to 75% on day of life 28; in the 901- to 1000-g birth weight stratum, actuarial survival improved from 88%, to 94%, and then to 98% throughout the same times, respectively. Similar trends were obtained when data were stratified by gestational age. CONCLUSIONS: Survival in the smallest infants improves dramatically during the first few days of life, but there is a significant risk for late death in the smallest of these infants. 相似文献
26.
Gonzales AJ; Christensen JG; Preston RJ; Goldsworthy TL; Tlsty TD; Fox TR 《Carcinogenesis》1998,19(7):1173-1183
27.
28.
Hua Qin Brendan T Keenan Diego R Mazzotti Fernando Vaquerizo-Villar Jan F Kraemer Niels Wessel Sergio Tufik Lia Bittencourt Peter A Cistulli Philip de Chazal Kate Sutherland Bhajan Singh Allan I Pack Ning-Hung Chen Ingo Fietze Thorarinn Gislason Steven Holfinger Ulysses J Magalang Thomas Penzel 《Sleep》2021,44(5)
Study ObjectivesPatients with obstructive sleep apnea (OSA) exhibit heterogeneous heart rate variability (HRV) during wakefulness and sleep. We investigated the influence of OSA severity on HRV parameters during wakefulness in a large international clinical sample.Methods1247 subjects (426 without OSA and 821 patients with OSA) were enrolled from the Sleep Apnea Global Interdisciplinary Consortium. HRV parameters were calculated during a 5-minute wakefulness period with spontaneous breathing prior to the sleep study, using time-domain, frequency-domain and nonlinear methods. Differences in HRV were evaluated among groups using analysis of covariance, controlling for relevant covariates.ResultsPatients with OSA showed significantly lower time-domain variations and less complexity of heartbeats compared to individuals without OSA. Those with severe OSA had remarkably reduced HRV compared to all other groups. Compared to non-OSA patients, those with severe OSA had lower HRV based on SDNN (adjusted mean: 37.4 vs. 46.2 ms; p < 0.0001), RMSSD (21.5 vs. 27.9 ms; p < 0.0001), ShanEn (1.83 vs. 2.01; p < 0.0001), and Forbword (36.7 vs. 33.0; p = 0.0001). While no differences were found in frequency-domain measures overall, among obese patients there was a shift to sympathetic dominance in severe OSA, with a higher LF/HF ratio compared to obese non-OSA patients (4.2 vs. 2.7; p = 0.009).ConclusionsTime-domain and nonlinear HRV measures during wakefulness are associated with OSA severity, with severe patients having remarkably reduced and less complex HRV. Frequency-domain measures show a shift to sympathetic dominance only in obese OSA patients. Thus, HRV during wakefulness could provide additional information about cardiovascular physiology in OSA patients.Clinical Trial Information: A Prospective Observational Cohort to Study the Genetics of Obstructive Sleep Apnea and Associated Co-Morbidities (German Clinical Trials Register - DKRS, DRKS00003966) https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00003966 相似文献
29.
Self‐perceived mouthfeel and physico‐chemical surface effects after chewing gums containing sorbitol and Magnolia bark extract
下载免费PDF全文
![点击此处可从《European journal of oral sciences》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Stefan W. Wessel Henny C. van der Mei Anje M. Slomp Betsy van de Belt‐Gritter Michael W. J. Dodds Henk J. Busscher 《European journal of oral sciences》2017,125(5):379-384
The European Food Safety Authority recognizes the contribution of sugar‐free chewing gum to oral health through increased salivation, clearance of food debris, and neutralization of biofilm pH. Magnolia bark extract is a gum additive shown to reduce the prevalence of bad‐breath bacteria but its effects on self‐perceived mouthfeel are unknown. This paper aims to relate the effects of sorbitol‐containing chewing gum, with and without Magnolia bark extract, on tooth‐surface hydrophobicity and salivary‐film composition with self‐perceived mouthfeel. In a crossover clinical trial, volunteers chewed sorbitol‐containing gum, with or without Magnolia bark extract added, three times daily during a 4‐wk time period. A subset of volunteers also chewed Parafilm as a mastication control. Oral moistness and tooth smoothness were assessed using questionnaires, and intra‐oral water‐contact angles were measured before, immediately after, and 60 min after, chewing. Simultaneously, saliva samples were collected, placed on glass slides, and the compositions of the adsorbed film were measured using X‐ray photoelectron spectroscopy. Chewing of gum, regardless of whether or not it contained Magnolia bark extract, improved self‐perceived mouthfeel up to 60 min, concurrent with a more hydrophilic tooth surface and an increased amount of O1s electrons bound at 532.6 eV in salivary films. Chewing of Parafilm affected neither tooth‐surface hydrophobicity nor salivary‐film composition. Accordingly, adsorption of sorbitol, rather than the presence of Magnolia bark extract or increased salivation, is responsible for improved self‐perceived mouthfeel. 相似文献
30.
Meyerfeldt U Wessel N Schütt H Selbig D Schumann A Voss A Kurths J Ziehmann C Dietz R Schirdewan A 《International journal of cardiology》2002,84(2-3):141-151
BACKGROUND: We tested whether or not heart rate variability (HRV) changes can serve as early signs of ventricular tachycardia (VT) and predict slow and fast VT in patients with an implantable cardioverter defibrillator (ICD). METHODS AND RESULTS: We studied the ICD stored 1000 beat-to-beat intervals before the onset of VT (131 episodes) and during a control time without VT (74 series) in 63 chronic heart failure ICD patients. Standard HRV parameters as well as two nonlinear parameters, namely 'Polvar10' from symbolic dynamics and the finite time growth rates 'Fitgra9' were calculated. Comparing the control and the VT series, no linear HRV parameter showed a significant difference. The nonlinear parameters detected a significant increase in short phases with low variability before the onset of VT (for time series with less than 10% ectopy, P<0.05). Subdividing VT into fast (cycle length 270 ms) events, we found that the onset of slow VT was characterized by a significant increase in heart rate, whereas fast VT was triggered during decreased heart rates, compared to the control series. CONCLUSIONS: Our data may permit the development of automatic ICD algorithms based on nonlinear dynamic HRV parameters to predict VT before it starts. Furthermore, they may facilitate improved prevention strategies. 相似文献