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   646篇
  免费   37篇
  683篇
  2023年   3篇
  2022年   18篇
  2021年   27篇
  2020年   13篇
  2019年   14篇
  2018年   19篇
  2017年   21篇
  2016年   20篇
  2015年   34篇
  2014年   34篇
  2013年   35篇
  2012年   40篇
  2011年   36篇
  2010年   26篇
  2009年   23篇
  2008年   28篇
  2007年   39篇
  2006年   37篇
  2005年   34篇
  2004年   26篇
  2003年   18篇
  2002年   14篇
  2001年   10篇
  2000年   9篇
  1999年   10篇
  1998年   12篇
  1997年   6篇
  1996年   5篇
  1995年   9篇
  1994年   3篇
  1993年   6篇
  1992年   11篇
  1991年   1篇
  1990年   3篇
  1989年   2篇
  1988年   5篇
  1987年   1篇
  1986年   4篇
  1985年   2篇
  1984年   4篇
  1983年   4篇
  1982年   2篇
  1981年   3篇
  1979年   1篇
  1977年   3篇
  1976年   1篇
  1975年   3篇
  1974年   1篇
  1973年   2篇
  1970年   1篇
排序方式: 共有683条查询结果,搜索用时 15 毫秒
671.
Acute gastric dilatation in two black and white colobus monkeys is described. The subfamily colobini have a ruminant-like stomach and a pregastric fermentation, of important for the observations described.  相似文献   
672.
ObjectiveWe aimed to determine the prevalence and clinical characteristics of self-reported hyperthyroidism in patients with sarcoidosis.MethodsA national registry-based study investigating 3836 respondents to the Sarcoidosis Advanced Registry for Cures questionnaire in the period between June 2014 and August 2019 was conducted. This registry is generated from a web-based questionnaire that is self-reported by patients with sarcoidosis. We compared patients with sarcoidosis who had hyperthyroidism with those who did not. We used multivariate logistic regression analysis to study the association between hyperthyroidism and different cardiac manifestations in patients with sarcoidosis.ResultsThree percent of the study respondents self-reported having hyperthyroidism and were generally middle-aged Caucasian women. Compared with patients without hyperthyroidism, patients with hyperthyroidism had more sarcoidosis-related comorbidities (59% vs 43%, P = .001) and more steroid-related comorbidities (56% vs 44%, P = .01), but there was no difference in the sarcoidosis-specific treatments they received, which included corticosteroids. Patients with hyperthyroidism reported sarcoidosis involvement of the heart (26.6% vs 14.9%, P = .005), kidneys (14.9% vs 8%, P = .033) and sinuses (17.7% vs 10.2%, P = .030) more frequently. Cardiac manifestations that were more frequently reported in patients with hyperthyroidism included atrial arrhythmias (11.3% vs 6.3%, P = .046), ventricular arrhythmias (17.2% vs 7.5%, P < .001), congestive heart failure (10.4% vs 5%, P = .017), and heart block (9.4% vs 4.7%, P = .036).ConclusionHyperthyroidism is infrequent in patients with sarcoidosis but is potentially associated with different cardiac manifestations. We suggest considering routine screening for hyperthyroidism in patients with sarcoidosis, especially in those with cardiac involvement. Further studies are needed to investigate the impact of identifying and treating hyperthyroidism in patients with sarcoidosis.  相似文献   
673.
674.
Coal-smoke emissions of a thermal power plant affected the physio-chemical status of Peristrophe bicalyculata (Reth) Nees, as observed at the pre-flowering, flowering and post-flowering stages of plant growth. The nitrate level was raised while nitrate reductase activity, and the soluble protein content of leaf declined heavily at the polluted site during different stages of plant growth, compared to the control. The rate of photosynthesis also decreased under the pollution stress. Sugar level in root, stem and leaves increased with growing age of the plant but was always lower at the polluted site than at the reference site. In roots, the difference was marginal till flowering stage and quite conspicuous afterwards; stems showed a reverse pattern of variation. Sulphur content was higher at the polluted site in all the organs and at each stage of the plant life. The Zn and Fe concentrations were reduced in all plant parts under the pollution stress. Copper content in root was consistently low at the polluted site. In the stem and leaves, however, it was almost equal on both the sites at the pre-flowering stage but showed a wide difference during the later part of plant ontogeny.  相似文献   
675.
676.
Agnosia.     
Object recognition can break down in a variety of ways after brain damage. The resulting different forms of agnosia provide us with useful constraints on theories of normal object recognition. Recent studies suggest a division of labor for the recognition of different types of stimuli (common objects, words, faces, direction of eye gaze, spatial relations among parts of the human body), a high degree of interactivity in the processes underlying object recognition, and the possibility that recognition and awareness of recognition may be neurally distinct.  相似文献   
677.
Street dust samples from urban and suburban areas were collected from the city of Karak, Jordan, during the summer season of 2004. Samples were analyzed for their heavy metal concentrations (Pb, Cu, Zn, Ni, Fe, Cr, Cd, and Mn). The results showed that all heavy metals are higher in city urban areas than the surrounding suburbs. The distribution and concentrations of heavy metals in all areas show automobile originated sources such as emissions and wear and tear of automobiles were the main source of pollution. Despite the fact that the city of Karak and the capital Amman are under the same climatic conditions and same type of fuel used in both cities, the heavy metal concentrations of street dust samples were lower in Karak than Amman due to the lower traffic density.  相似文献   
678.
679.
680.
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