首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   159篇
  免费   2篇
耳鼻咽喉   2篇
儿科学   4篇
妇产科学   24篇
基础医学   11篇
口腔科学   7篇
临床医学   19篇
内科学   26篇
皮肤病学   15篇
神经病学   3篇
特种医学   2篇
外科学   22篇
综合类   2篇
预防医学   5篇
眼科学   1篇
药学   10篇
肿瘤学   8篇
  2016年   1篇
  2015年   3篇
  2014年   1篇
  2013年   4篇
  2010年   3篇
  2009年   2篇
  2008年   1篇
  2007年   2篇
  2006年   1篇
  2005年   2篇
  2003年   1篇
  2000年   3篇
  1999年   3篇
  1998年   3篇
  1997年   7篇
  1995年   3篇
  1994年   3篇
  1993年   2篇
  1992年   6篇
  1991年   2篇
  1990年   3篇
  1989年   2篇
  1988年   7篇
  1987年   2篇
  1986年   4篇
  1985年   5篇
  1983年   3篇
  1982年   1篇
  1980年   2篇
  1979年   1篇
  1978年   1篇
  1977年   3篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
  1969年   3篇
  1968年   1篇
  1967年   2篇
  1964年   1篇
  1963年   1篇
  1959年   1篇
  1958年   7篇
  1957年   15篇
  1956年   12篇
  1955年   17篇
  1954年   9篇
  1948年   1篇
排序方式: 共有161条查询结果,搜索用时 953 毫秒
1.
2.
Semantic priming effects (behavioral and electrophysiological) were compared in the visual and auditory modalities across three stimulus onset asynchronies (SOAs; 0, 200, and 800 ms). When both prime and target were presented in the visual modality (the prime just to the left of a fixation point and the target to the right) there were N400 priming effects present across the three SOAs. However, the N400 in the 0-ms SOA condition extended longer in time (800 vs. 500 ms) than in the other SOAs. When both the prime and target were presented in the auditory modality (the prime to the right ear and the target to the left), the largest priming effects were found for the 800-ms SOA. Moreover, there was a relatively early priming effect present in the 0- and 800-ms SOA conditions but not in the 200-ms condition. The results are discussed in terms of modality differences in the time course of word comprehension processes.  相似文献   
3.
Abstract: Right ventricular (RV) failure during the use of a left ventricular assist device (LVAD) is the leading cause of death in circulatory support patients. Previous work, both experimentally and clinically, has shown the difficulties in predicting the behavior of the right ventricle at the start of LVAD. An experimental study has been designed to evaluate RV functional changes during LVAD and its relation to preload changes. The model used adult mongrel pigs (n = 10). Right ventricular functional parameters were measured with a thermodilution RV ejection fraction catheter. The left ventricle was supported by a Nippon Zeon blood pump. Two groups were studied, the first one was the LVAD–off group (n = 5) and the other was the LVAD–on group (n = 5) which was supported by LVAD at maximum flow. Change of cardiac output, mean pulmonary artery pressure (PAP), RV stroke work, and RV ejection fraction in both groups were not significantly different. However, the relationship between right ventricular end–diastolic pressure (RV–EDP) and right ventricular stroke volume (RVSV) was significantly changed at a high level of RV–EDP. When RV–EDP was over 6. 5 mm Hg in the LVAD–off group, RVSV decreased to 52. 3 ± 11. 5 ml while in the LVAD–on group, RVSV increased to 97. 2 ± 22. 0 ml. The change in PAP in the LVAD–on group was lower than in the LVAD–off group. We conclude that, at the volume overload state, LVAD can reduce the afterload of the right ventricle and maintain Frank–Starling's effect, thus having a beneficial effect on right ventricular performance.  相似文献   
4.
A total of 174 families of service personnel with children between3 and 6 years of age were studied over a 6 month period. Allcontacts with the general practitioner, both in and out of hourstogether with the local casualty department were recorded. Mothersof the children were posted a specialty designed questionnaireto measure how seriously they perceived various childhood symptomsto be and a copy of the general health questionnaire, 28 questionversion (GHQ 28). The perceived severity questionnaire had beenpiloted previously in a neighbouring practice. The overall responserate was 77%. Analyses of the data showed that the factors mostsignificantly associated with a child's consultation frequencywere the psychological state of the mother, the mother's ownconsultation frequency and the number of children in the family;the last being an inverse relationship. No evidence was foundto suggest that the perception of the severity of illness variedwith the psychological state of the mother. In addition, thechildhood consultation rate was not influenced by the mother'sperception of the severity of childhood illness as measuredby the perceived severity questionnaire. Other factors suchas the age of the mother or child, within the age range studied,were not found to be significantly related to the child's frequencyof consulting. A mother's own consultation frequency was highlycorrelated with her GHQ 28 score, but more specifically withthe subsections that scored for depression and somatic symptoms.From the study, doctors who see children should seriously considerthe main reasons for a child's consultation. In particular,as mothers often make the decision as to whether their childshould see the doctor, the main patient may be the parent notthe child. Mothers who present themselves frequently may alsohave a high level of psychological distress.  相似文献   
5.
6.
The developing cardiovascular system is a sensitive target of many environmental pollutants, including dioxins, dioxin-like polychlorinated biphenyls (PCBs), and some pesticides such as methyl parathion. Laboratory research has utilized a variety of vertebrate models to elucidate potential mechanisms that mediate this cardioteratogenicity and to establish the sensitivity of different species for predicting potential risk to environmental and human health. Studies of dioxin and dioxin-like PCBs have illustrated that piscine, avian, and mammalian embryos exhibit cardiovascular structural changes and functional deficits, although the specific characteristics vary among the individual models. Piscine models typically exhibit reduced blood flow, altered heart looping, and reduced heart size and contraction rate. The chick embryo exhibits extensive cardiac dilation, thinner ventricle walls, and reduced responsiveness to chronotropic stimuli, while the murine embryo exhibits reduced heart size. It is notable that in all models the dioxin-associated cardioteratogenicity is associated with increases in cardiovascular apoptosis and decreases in cardiocyte proliferation. While the cardiotertogenicity in piscine and avian species is associated with overt morbidity and mortality, that is not the case for the murine embryo. However, murine offspring exposed during development to dioxin exhibit cardiac hypertrophy and an increased sensitivity to a second cardiovascular insult in adulthood. Thus, although the mammalian embryo is less sensitive to cardiovascular defects by dioxin and dioxin-like compounds, developmental exposure increases the risk of cardiovascular disease later in life. The impact of developmental exposure to dioxin-like chemicals on human cardiovascular disease susceptibility is not known. However, recent animal research has confirmed human epidemiology studies that dioxin exposure in adulthood is associated with hypertension and cardiovascular disease.  相似文献   
7.
8.
The spectrum of angiographic finding in 20 patients with transitional cell carcinomas of the kidney is described. In 15 of 20 patients (75%), prospective diagnosis of transitional cell carcinomas were made because of a combination of the angiographic findings; tumour vessels, tumour stain, prominent pelviureteric arteries and arterial encasement. In 4 patients with negative angiograms the lesions were relatively small in size and were situated within the renal parenchyma, primarily involving the calyces. The use of pharmacoangiographic agents such as epine-phrine and priscoline improved the angiographic visualization of transitional cell carcinomas of the kidney. For the past several years angiography has had a central role in the evaluation of patients with hematuria and renal masses1. 5,6,7,8. Although the use of diagnostic ultrasound and renal puncture have eliminated angiography from the diagnosis of renal cysts, most renal masses which are solid or which have equivocal findings at ultrasound still undergo angiography. At the same time, the decreasing use of retrograde urography has resulted in more frequent angiography in patients with unilateral nonfunctioning kidneys. Transitional cell carcinomas of the renal pelvis are an important cause of both hematuria and non-functioning kidneys. We have therefore reviewed our material to reassess the angiographic abnormalities caused by the transitional cell carcinomas and the overall accuracy of the angiography in the diagnosis of these lesions.  相似文献   
9.
10.
ABSTRACT. We report a preterm infant with ventricular arrhythmias secondary to hyperkalaemia in the first 48 hours of life. The arrhythmias were life threatening and required pharmacological and electrical cardioversion. Aspects of neonatal hyperkalaemia and related arrhythmias are discussed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号