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   571篇
  免费   37篇
  国内免费   3篇
耳鼻咽喉   7篇
儿科学   47篇
妇产科学   8篇
基础医学   57篇
口腔科学   14篇
临床医学   89篇
内科学   120篇
皮肤病学   3篇
神经病学   63篇
特种医学   12篇
外科学   41篇
预防医学   66篇
眼科学   15篇
药学   36篇
肿瘤学   33篇
  2023年   3篇
  2022年   7篇
  2021年   17篇
  2020年   13篇
  2019年   12篇
  2018年   16篇
  2017年   11篇
  2016年   19篇
  2015年   14篇
  2014年   19篇
  2013年   28篇
  2012年   47篇
  2011年   43篇
  2010年   22篇
  2009年   14篇
  2008年   30篇
  2007年   42篇
  2006年   31篇
  2005年   22篇
  2004年   35篇
  2003年   20篇
  2002年   11篇
  2001年   7篇
  2000年   5篇
  1999年   4篇
  1998年   4篇
  1997年   4篇
  1996年   6篇
  1995年   5篇
  1994年   8篇
  1993年   3篇
  1992年   8篇
  1991年   6篇
  1990年   2篇
  1989年   6篇
  1988年   5篇
  1987年   5篇
  1986年   4篇
  1985年   7篇
  1984年   7篇
  1983年   2篇
  1982年   6篇
  1979年   5篇
  1977年   2篇
  1975年   3篇
  1974年   3篇
  1973年   3篇
  1972年   6篇
  1971年   2篇
  1962年   1篇
排序方式: 共有611条查询结果,搜索用时 0 毫秒
1.
2.
We studied the volume of trapped gas (VTG), using a nitrogen washout method, before and after bronchodilation in four groups with theoretically increasing risk of developing pulmonary emphysema: (1) nonsmoking healthy controls (PiMn), (2) nonsmoking subjects with an intermediate alpha 1-antitrypsin deficiency (PiMZn), (3) smoking subjects with normal concentration of alpha 1-antitrypsin, and (4) smoking PiMZ subjects. VTG was the only lung function variable that showed a significant difference between PiMZn and PiMn subjects but only after bronchodilation. Some conventional lung function tests also distinguished smokers from nonsmokers of both genotypes but VTG was the most sensitive test. VTG decreased after salbutamol inhalation in the control group but showed a consecutively larger increase with more risk factors of developing emphysema. An increase in VTG after bronchodilation may be a sign of alveolar abnormality preceding development of clinical lung emphysema.  相似文献   
3.
BACKGROUND: The aim of this study was to find an effective treatment for hypocalcemic symptoms during plateletpheresis and to evaluate if a combination of calcium, magnesium and vitamin D3 is more effective in comparison to routine calcium supplementation. MATERIAL AND METHODS: A study group consisting of 10 donors, having a history of previous hypocalcemic symptoms during plateletpheresis, donated platelets twice in a one-month period. During the first donation combination tablets (600mg Ca+300mg Mg+100IU vitamin D3) were used to treat hypocalcemic symptoms while routine treatment calcium carbonate tablets (1000mg Ca) were used during the second donation. If symptoms persisted after 10min the same dose was repeated. A control group, with no supplementation, consisting of five donors, with no history of hypocalcemic symptoms, were included. Donor subjective symptoms were graded and recorded on four occasions: at the start of plateletpheresis, when symptoms appeared, 10min after the first tablet and at the end of donation. Samples for analysis of ionized calcium (iCa), magnesium and potassium were also taken at the same occasions. RESULTS: All donors from the study group experienced minor or medium hypocalcemic symptoms and needed a second dose of supplementation. Calcium carbonate tablets completely relieved the hypocalcemic symptoms in six donors, it had no effect on three donors and one donor experienced aggravated symptoms. The combination tablets completely relieved the symptoms in three donors, one donor experienced a partial relief and six donors had no relief of symptoms. There were no significant differences in iCa, potassium and magnesium levels were noted in the study group irrespective of which tablets were used for treatment of hypocalcemic symptoms. After plateletpheresis the median iCa levels declined by 30% and potassium levels declined by 3-11% in all donors while the magnesium levels were not significantly affected. There was no correlation between the presence of symptoms and the changed levels of iCa or magnesium. CONCLUSION: Addition of magnesium and vitamin D3 to calcium seems to have no beneficial effect in the treatment of hypocalcemic symptoms in plateletpheresis donors.  相似文献   
4.
Ventilatory efficiency for eliminating CO2 is expressed by the physiological dead space, VD phys = (1-PE CO2/Pa CO2) x VT, where PE is the mixed exhaled and Pa the arterial CO2-tension and VT the tidal volume. We used data from the multiple breath N2-wash-out with oxygen for calculating a functional dead space for nitrogen. VDF N2 = (1-FEN2/FidN2) x VT.FEN2 is the mixed exhaled N2-fraction and FidN2 the calculated mean alveolar N2-fraction during a wash-out with the same number of breaths to reach 2% N2 in end tidal air, but having completely even distribution. FidN2 is shown to be 0.20 +/- 0.01 for wash-outs using 20-150 breaths. The method was applied to wash-outs from 21 healthy volunteers, 18 patients with chronic obstructive lung disease and two subjects with acute bronchospasm. VDF was well related to VD phys CO2 (r = 0.78) but higher than the latter. In subjects with lung disease VDF was inversely related to the degree of obstruction expressed by forced expiratory volume in one second per cent of vital capacity (r = 0.85). The subjects with bronchospasm had very high VD/VTF in relation to their FEV%. If airway dead space predicted from height and sex is subtracted from VDF, the resulting alveolar dead space will be a good expression for uneven gas distribution in the lungs. We also deduced a direct mathematical relation between lung clearance index and VD/VTF. The documented good reproducibility of LCI is thus also valid for VD/VTF, while the latter better expresses ventilatory efficiency.  相似文献   
5.
Functional and alveolar dead spaces for nitrogen (VDF and VDalv) were calculated in a population of 20 male and 20 female heavy smokers and compared to data from static and forced spirometry (functional residual capacity [FRC], residual volume [RV], lung clearance index [LCI] and volume of trapped gas [VTG]) obtained with the same multiple-breath nitrogen wash-out as the dead spaces, and to variables considered sensitive to small airways disease measured with a single-breath nitrogen elimination (closing volume in per cent of vital capacity [CV%], closing capacity in per cent of total lung capacity [CC%] and slope index [SI]). Both nitrogen dead spaces increased with tidal volume in smokers as well as in healthy non-smokers. The majority of smokers were outside the predicted mean +2 SD for VTG (75%), CC and VDalv (70%) and SI (65%). The following variables were less sensitive for disclosing abnormality: CV (55%), RV (53%), LCI (38%) and forced expired volume in the first second (FEV1, 33%). If high sensitivity is considered preferable in epidemiological studies, the nitrogen dead spaces are equally as sensitive as the better of earlier described tests, and significantly superior to LCI and FEV1. Being tests that measure alveolar distribution of inhaled gas, they are probably sensitive to small airways disease.  相似文献   
6.
Journal of Immigrant and Minority Health - Parental support is of paramount importance in the promotion of positive parenting, strengthening parenthood and protecting children from disadvantages...  相似文献   
7.
8.
9.
10.
Maintaining the well‐being of older people who are approaching the end‐of‐life has been recognised as a significant aspect of well‐being in general. However, there are few studies that have explicitly focused on at‐homeness among older people. This study aims to illuminate meanings of at‐homeness among older people with advancing illnesses. Twenty men and women, aged 85 or older, with advancing illnesses and who lived in their own homes, in nursing homes or in short‐term nursing homes in three urban areas of Sweden were strategically sampled in the study. Data were generated in narrative interviews, and the analysis was based on a phenomenological hermeneutical method. After obtaining a naïve understanding and conducting structural analyses, two aspects of the phenomenon were revealed: at‐homeness as being oneself and at‐homeness as being connected. At‐homeness as being oneself meant being able to manage ordinary everyday life as well as being beneficial to one's life. At‐homeness as being connected meant being close to significant others, being in affirming friendships and being in safe dependency. Here, at‐homeness is seen as a twofold phenomenon, where being oneself and being connected are interrelated aspects. Being oneself and being connected are further interpreted by means of the concepts of agency and communion, which have been theorised as two main forces of the human being.  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