全文获取类型
收费全文 | 275篇 |
免费 | 13篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 5篇 |
妇产科学 | 2篇 |
基础医学 | 23篇 |
口腔科学 | 14篇 |
临床医学 | 22篇 |
内科学 | 31篇 |
皮肤病学 | 5篇 |
神经病学 | 7篇 |
特种医学 | 97篇 |
外科学 | 36篇 |
综合类 | 6篇 |
预防医学 | 12篇 |
眼科学 | 2篇 |
药学 | 12篇 |
肿瘤学 | 6篇 |
出版年
2021年 | 3篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 9篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 8篇 |
2009年 | 7篇 |
2008年 | 4篇 |
2007年 | 7篇 |
2006年 | 12篇 |
2005年 | 4篇 |
2004年 | 11篇 |
2003年 | 15篇 |
2002年 | 7篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 12篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1944年 | 1篇 |
排序方式: 共有288条查询结果,搜索用时 31 毫秒
21.
Objective. This study documents and traces the evolution of triple rhythm (Waltz) linking the great veins, corresponding systemic or
pulmonary venous sinuses and pectinated right or left atrium in frog, turtle, snake and human hearts. Alternating rhythm (duet)
between systemic and pulmonary veins has also been documented in these hearts.
Material Studied. The hearts of six dead hammer-head sharks were examined with the naked eye. Air-breathing, fresh-water fish (three Channa
striata and three Indian catfish) were anaesthetised with ketamine and their pharynx insufflated with oxygen. Six frogs, three
turtles, and two snakes were anaesthetised, intubated and ventilated. Contractions of the exposed hearts of these animals
were correlated with their electrocardiograms using superimposed videos. The human heart was observed carefully during surgery
through median sternotomy or anterolateral thoracotomy by visual inspection especially during instillation of or recovery
from cardioplegia. Digital videos were taken and studied in slow motion replay later.
Observations. In the air-breathing fish, Channa striata and Indian catfish and presumably the shark, the cardinal veins and thin walled
sinus venosus do not contract. In the frog, turtle, and snake there is sequential contraction of the systemic veins, systemic
venous sinus and pectinated right atrium. Likewise, there is waltz on the arterial side. There is a duet between systemic
and pulmonary veins, contractions of the former preceding the latter in the frog, turtle and snake. The observations are similar
in the human heart except that the inferior vena cava does not contract.
Conclusions. There is sequential contraction of the superior vena cava, the systemic venous sinus and the pectinated part of the right
atrium in the human heart. Likewise, there is a waltz linking the terminal pulmonary veins, pulmonary venous sinus and pectinated
part of the left atrium in the human heart. This waltz or triple rhythm, as well as a duet between the systemic and pulmonary
veins are seen in frog, turtle and snake. The duet is also observable in the human heart, during recovery from cardioplegia.
It is likely that the waltz and duet are conducted by a neurogenic mechanism.
Clinical Implications. The understanding, preservation and restoration of the mechanism sustaining supraventricular waltz and duet is relevant
to surgical and interventional procedures for control of atrial arrhythmia, Fontan circulation, technique for cardiac transplantation
and planning atriotomies. 相似文献
22.
23.
Sanjana VM; Johnston PA; Robertson CR; Jamison RL 《The American journal of physiology》1976,231(2):313-318
24.
Rodríguez-Larralde A Mijares ME Nagy E Espinosa R Ryder E Diez-Ewald MP Torres E Coll-Sangrona E Rodríguez-Roa E Carvajal Z Lundberg U Campos G Gill A Arocha-Piñango CL;Grupo FRICVE 《Investigación clínica》2005,46(2):157-168
Previous studies in Europe, U.S.A and Japan have revealed an inverse relationship between socioeconomic levels and fibrinogen concentration. Similar results have been reported in a smaller number of studies for concentrations of von Willebrand factor. In this opportunity we present results on the relationship between smoking, drinking, physical activity, age and socioeconomic level on fibrinogen and von Willebrand factor concentrations in a Venezuelan sample. The control population consisted of 978 men and 968 women. Patients with coronary heart disease were 172 males and 78 females. The presence of one or more of the following conditions: smoking or less than 5 years of having quit, non drinkers or drinking in excess, and a reduced physical activity, was considered a health related risk factor for high levels of these two haemostatic variables. Our results indicate that in Controls, the socioeconomic level had a significant effect on fibrinogen and von Willebrand factor levels, only in women: those of lower socioeconomic levels had the highest concentrations. This difference was maintained when age was taken into account. Health related behaviors had no significant effect on either variable. In patients, age had no effect on either variable. The health behavior risk factor had a significant effect only on fibrinogen of male patients, and socioeconomic level had a significant effect only on the fibrinogen of female patients. More studies in Venezuela are recommended, in order to increase our knowledge on the relationship between socioeconomic levels, haemostatic markers and the occurrence of coronary heart disease. 相似文献
25.
26.
27.
The effects of an ionic contrast agent, meglumine iothalamate (Conray-60), and two newer low-osmolality radiographic contrast media, sodium meglumine ioxaglate (Hexabrix) and iopamidol (B-15,000), on platelet aggregation and secretion responses were studied. All three agents inhibited platelet responses during stimulation with adenosine diphosphate (ADP), epinephrine, and collagen. Platelet function was inhibited by iothalamate at concentrations of 11 mg iodine/ml and above, and by the newer agents at concentrations above 30 mg iodine/ml. Addition of exogenous calcium decreased the iothalamate-induced inhibition of aggregation but did not improve dense granule secretion. There was no consistent effect of exogenous calcium on platelet inhibition by iopamidol and ioxaglate. These studies indicate that the newer agents inhibit platelet function less than iothalamate does, and that chelation of Ca2+ may not be the major mechanism of platelet inhibition by contrast agents. 相似文献
28.
Percutaneous transluminal angioplasty of the femoropopliteal artery: initial and long-term results 总被引:4,自引:0,他引:4
Patients with dilated stenoses and recanalized occlusions were evaluated to assess the initial and long-term results of percutaneous transluminal angioplasty (PTA) in the femoropopliteal artery. The follow-up period was at least 1 year. The initial success rate was 84% (128/164). The initial results were influenced by the radiologist's experience, catheter selection, and type of lesion. The 5- and 7-year cumulative patency rates were 70% and 60%. There was no difference in long-term patency between initially successful stenoses and short (less than 3 cm) occlusions. Both the morphology and location of the stenotic lesion influenced the long-term results. Although many factors influence the initial and long-term success rate, results of this study justify PTA in the femoropopliteal artery. Patients with localized stenoses and short occlusions are best suited for this treatment. 相似文献
29.
Patients on hemodialysis are at increased risk for developing active tuberculosis (TB) after primary infection. Although this increased risk is well documented, the prevalence of TB infection, as indicated by a positive tuberculin skin test (TST), is not well described. End-stage renal disease is also known to be a risk factor for skin test anergy, but the rate of anergy in hemodialysis patients is unclear. We sought to identify rates of anergy and TST positivity in patients at four hemodialysis units in St Louis, Missouri, from June 1996 through August 1996. Data obtained from patients and medical records included age, years on hemodialysis, medical history, and basic laboratory data. Patients without a history of TB or a positive TST had a TST with Tubersol, as well as candida and tetanus controls, placed by the Mantoux method. Tests were read 48 hours later. Of the patients enrolled at these units, 307 of 331 (93%) were evaluated. Patients had a mean age of 58 years (range, 19 to 91 years) and had been on hemodialysis for a mean of 3.7 years (range, 1 week to 18.7 years). Blacks made up 81% of the population. A history of a positive TST was obtained from 24 patients (8%), and an additional seven (2%) had a history of active TB. Of the 276 patients tested, 93 did not respond to either control antigen, but five of these patients had a positive TST, leaving 88 (32%) anergic. Anergy was related to age, immunosuppressive drug use, and the reagents used, but not to urea reduction ratio. Positive TSTs were found in 17 of 188 of nonanergic patients (9%) (6% of all tested patients). Overall, 48 of 307 patients (16%) had a positive TST or history of TB. TB or a positive TST was associated with liver disease and peptic ulcer disease, but not socioeconomic status. All 17 newly identified TST-positive patients received chest radiographs. No new cases of active TB were found. Only two of 17 of these patients (12%) were started on isoniazid (INH) prophylaxis. We identified high rates of TST positivity and anergy in the hemodialysis patients tested. Hemodialysis patients should receive regular TST screening, and INH prophylaxis needs to be more strongly encouraged. Studies are ongoing to define the rate of TST conversion over time. 相似文献
30.
Breitenseher MJ; Metz VM; Gilula LA; Gaebler C; Kukla C; Fleischmann D; Imhof H; Trattnig S 《Radiology》1997,203(1):245