全文获取类型
收费全文 | 496篇 |
免费 | 34篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 19篇 |
妇产科学 | 14篇 |
基础医学 | 70篇 |
口腔科学 | 12篇 |
临床医学 | 51篇 |
内科学 | 102篇 |
皮肤病学 | 4篇 |
神经病学 | 27篇 |
特种医学 | 66篇 |
外科学 | 41篇 |
综合类 | 5篇 |
一般理论 | 3篇 |
预防医学 | 73篇 |
眼科学 | 2篇 |
药学 | 13篇 |
中国医学 | 1篇 |
肿瘤学 | 8篇 |
出版年
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 23篇 |
2014年 | 22篇 |
2013年 | 20篇 |
2012年 | 17篇 |
2011年 | 15篇 |
2010年 | 19篇 |
2009年 | 6篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 20篇 |
2005年 | 18篇 |
2004年 | 15篇 |
2003年 | 14篇 |
2002年 | 8篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 15篇 |
1996年 | 13篇 |
1995年 | 12篇 |
1994年 | 17篇 |
1993年 | 11篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 17篇 |
1988年 | 18篇 |
1987年 | 13篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1969年 | 2篇 |
1968年 | 3篇 |
1957年 | 2篇 |
排序方式: 共有530条查询结果,搜索用时 609 毫秒
131.
BACKGROUND: The purpose of this study was to investigate the possibility of identifying laryngopharyngeal cancers by nuclear chromatin texture feature analysis of cell nuclei from mucosal scrapings obtained from clinically and cytologically noncancerous areas of the soft palate in patients with cancer. METHODS: The collective consisted of 68 controls and 77 cases of laryngopharyngeal carcinomas. After Feulgen staining, 3000 cell nuclei were automatically measured using a high-resolution image analyser (CytoSavant Oncometrics, Vancouver, BC, Canada). Texture features were extracted for calculation of a discriminant function, which allows the two groups to be distinguished. RESULTS: Two parameters allowed the two populations to be distinguished. The classifier reached an overall performance of 72.7% sensitivity, 82.4% specificity, a positive predictive value of 80.5%, a negative predictive value of 75.1%, and an area under the receiver operating characteristics (ROC) curve of 0.7754. CONCLUSION: Our work shows that subtle changes in the chromatin distribution in cell nuclei from ostensibly normal cells in the vicinity of carcinomas are demonstrable in the oral cavity of patients suffering from laryngopharyngeal cancers. It may be possible to develop this method into a valuable clinical tool to reduce the high rate of delayed diagnosis of oral and laryngopharyngeal cancers. 相似文献
132.
133.
Noise analysis of drug induced voltage clamp currents in denervated frog muscle fibres. 总被引:12,自引:0,他引:12
下载免费PDF全文
![点击此处可从《The Journal of physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1. Voltage clamp currents were recorded during iontophoretic application of steady doses of acetylcholine (ACh), carbachol or suberyldicholine to hyperpersensitive extrasynaptic regions of chronically denervated frog muscle fibers. Autocorrelation functions of drug induced current fluctuations were calculated and estimates of conductance gamma and average open time tau of the extrasynaptic ion channels were derived. 2. The average open time of an extrajunctional channel induced by acetylcholine is tauACh = 11 +/- 1-6 msec (+/- S.E.) at -80 mV and 8 degrees C. Carbachol and suberyldicholine open channels of tauCarb = 3-9 +/- 0-4 msec and tauSubCh = 19 +/- 2-5 msec (+/- S.E.) duration under the same conditions. The average open time of the extrasynaptic channel produced by each drug is three to five times longer than the value found for junctional channels in normal fibres. 3. The average open time of the extrajunctional channel is dependent on temperature and membrane potential. Lowering the temperature or increasing the membrane potential increases the average open time of the channels induced by any one of the drugs. 4. The conductance of a single extrajunctional channel opened by the action of acetylcholine is estimated to be gammaextra = 15 +/- 1-8 pmho (+/- S.E.). This is somewhat lower than the value of gammaep = 23 +/- 2 pmho (+/- S.E.) found for the conductance of a single open channel in the junctional membrane of normal fibres. The extrasynaptic channels opened by the action of carbachol and suberyldicholine have similar conductances to those produced by ACh. 5. The autocorrelation function of drug-induced current fluctuations, recorded at the former end-plate region of chronically denervated fibres often shows both a fast and a slow time constant. They correspond in value to the time constant of the autocorrelation function obtained from end-plate currents in normal fibres and from extrasynaptic currents in denervated fibres respectively. This could indicate that two populations of channels exist at the former end-plate region of denervated muscle fibres. 相似文献
134.
Pierre Feugier Deog-Yeon JO Jae Hung Shieh Karen L. MacKenzie JF Lesesve V Latger-Cannard D Bensoussan Ronald G Crystal Shahin Rafii JF Stoltz Malcolm A.S. Moore 《生物医学工程学杂志》2005,(Z1)
1 IntroductionCulture systems capable of expanding and/or maintaining hematopoietic stem cells will not only facilitate our understanding of stem cell biology, but also broaden clinical applications. Among various in vitro hematopoietic culture systems, co-cultures of marrow or CD34~ cells with an adherent stromal layer that can produce cytokines and extracellular matrix components most effectively supports long-term hematopoiesis (LTC), mimicking the bone marrow micro-environment.The OP-9 stromal cells ar... 相似文献
135.
GEORGE M. SPYRIDES DDS MS PHD JORGE PERDIGÅO DMD MS PHD CLÓVIS PAGANI DDS MS PHD MARIA AMÉLIA M. ARAÚJO DDS MS PHD SILVANA M.M. SPYRIDES DDS 《Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.]》2000,12(5):264-270
Background: Several studies have shown a reduction in enamel bond strengths when the bonding procedure is carried out immediately after vital bleaching with peroxides. This reduction in bond strengths has become a concern in cosmetic dentistry with the introduction of new “in‐office” and “waiting‐room” bleaching techniques. The aim of this in vitro study was to evaluate the effect of three bleaching regimens: 35% hydrogen peroxide (HP), 35% carbamide peroxide (CP), and 10% CP, on dentin bond strengths. Materials and Methods: One hundred and twenty fresh bovine incisors were used in this study. The labial surface of each tooth was ground flat to expose dentin and was subsequently polished with 600‐grit wet silicon carbide paper. The remaining dentin thickness was monitored and kept at an average of 2 mm. The teeth were randomly assigned to four bleaching regimens (n = 30): (A) control, no bleaching treatment; (B) 35% HP for 30 minutes; (C) 35% CP for 30 minutes; and (D) 10% CP for 6 hours. For each group, half of the specimens (n = 15) were bonded with Single Bond/Z100 immediately after the bleaching treatment, whereas the other half was bonded after the specimens were stored for 1 week in artificial saliva at 37°C. The specimens were fractured in shear using an Instron machine. Results: For the groups bonded immediately after bleaching, one‐way analysis of variance (ANOVA) followed by the Duncan's post hoc test revealed a statistically significant reduction in bond strengths in a range from 71% to 76%. For the groups bonded at 1 week, one‐way ANOVA showed that group B (35% HP for 30 min) resulted in the highest bond strengths, whereas 10% CP resulted in the lowest bond strengths. Student's t‐test showed that delayed bonding resulted in a significant increase in bond strengths for groups B (35% HP) and C (35% CP); whereas the group bleached with 10% CP (group D) remained in the same range obtained for immediate bonding. Storage in artificial saliva also affected the control group, reducing its bond strengths to 53% of the original. 相似文献
136.
137.
NORBERT M. van HEMEL M.D. JO J.A.M. DEFAUW M.D. GÉRARD M. GUIRAUDON M.D. JOHANNES C. KELDER M.D. EMILE R. JESSURUN M.D. JEF M.P.G. ERNST M.D. 《Journal of cardiovascular electrophysiology》1997,8(9):967-973
Late Results of Surgery for AF. Introduction: Currently, surgery- and catheter-mediated ablation is applied when drug refractoriness of atrial fibrillation is evident, although little is known about the long-term incidence of new atrial arrhythmia and the preservation of sinus node function.
Methods and Results: To address this issue, 30 patients with successful corridor surgery for lone paroxysmal atrial fibrillation and normal preoperative sinus node function were followed in a single outpatient department. Five years after surgery, the actuarial proportion of patients with recurrence of atrial fibrillation arising in the corridor was 8%± 5%, with new atrial arrhythmias consisting of atrial flutter and atrial tachycardia in the corridor 27%± 8%, and with incompetent sinus node requiring pacing therapy 13%± 6%. Right atrial transport was preserved in 69% of the patients without recurrence of atrial fibrillation and normal sinus node function. Stroke was documented in two patients.
Conclusions: Corridor surgery for atrial fibrillation is a transient or palliative treatment instead of a definitive therapy for drug refractory atrial fibrillation. This observation strongly affects patient selection for this intervention and constitutes a word of caution for other, non-pharmacologic interventions for drug refractory atrial fibrillation. 相似文献
Methods and Results: To address this issue, 30 patients with successful corridor surgery for lone paroxysmal atrial fibrillation and normal preoperative sinus node function were followed in a single outpatient department. Five years after surgery, the actuarial proportion of patients with recurrence of atrial fibrillation arising in the corridor was 8%± 5%, with new atrial arrhythmias consisting of atrial flutter and atrial tachycardia in the corridor 27%± 8%, and with incompetent sinus node requiring pacing therapy 13%± 6%. Right atrial transport was preserved in 69% of the patients without recurrence of atrial fibrillation and normal sinus node function. Stroke was documented in two patients.
Conclusions: Corridor surgery for atrial fibrillation is a transient or palliative treatment instead of a definitive therapy for drug refractory atrial fibrillation. This observation strongly affects patient selection for this intervention and constitutes a word of caution for other, non-pharmacologic interventions for drug refractory atrial fibrillation. 相似文献
138.
OS Ogah RO Akinyemi JO Adesina JKL Osinfade RF Ogundipe GD Adegbite OI Udofia SB Udoh OS Ojo AA Alabi T Majekodunmi AO Falase 《Cardiovascular journal of Africa》2011,22(6):297-302
Background
We sought to determine the prevalence of echocardiographically determined left ventricular systolic dysfunction in asymptomatic hypertensive subjects seen in Abeokuta, Nigeria.Methods
Echocardiography was performed in 832 consecutive hypertensive subjects referred for cardiac evaluation over a three-year period.Results
Data were obtained in 832 subjects (50.1% women) aged 56.0 ± 12.7 years (men 56.9 ± 13.3 years, women 55.0 ± 12.0 years, range 15–88). The prevalence of left ventricular systolic dysfunction (LVSD) was 18.1% in the study population (mild LVSD = 9.6%, moderate LVSD = 3.7% and severe LVSD = 4.8%). In a multivariate analysis, male gender, body mass index and LV mass were the predictors of LVSD.Conclusion
Significant numbers of hypertensive subjects in this study had varying degrees of left ventricular systolic dysfunction. Early introduction of disease-modifying drugs in these patients, such as angiotensin converting enzyme inhibitors or angiotensin receptor blockers may retard or prevent the progression to overt heart failure. 相似文献139.
140.