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   785篇
  免费   52篇
  2023年   5篇
  2022年   15篇
  2021年   30篇
  2020年   19篇
  2019年   16篇
  2018年   15篇
  2017年   10篇
  2016年   27篇
  2015年   52篇
  2014年   51篇
  2013年   51篇
  2012年   46篇
  2011年   69篇
  2010年   41篇
  2009年   40篇
  2008年   49篇
  2007年   51篇
  2006年   39篇
  2005年   34篇
  2004年   25篇
  2003年   24篇
  2002年   19篇
  2001年   5篇
  2000年   5篇
  1999年   3篇
  1998年   4篇
  1997年   4篇
  1996年   2篇
  1995年   3篇
  1994年   3篇
  1993年   7篇
  1991年   7篇
  1990年   4篇
  1989年   4篇
  1988年   5篇
  1986年   4篇
  1985年   3篇
  1984年   2篇
  1983年   5篇
  1982年   3篇
  1981年   2篇
  1980年   4篇
  1978年   2篇
  1975年   2篇
  1974年   2篇
  1969年   3篇
  1966年   2篇
  1961年   3篇
  1960年   2篇
  1926年   1篇
排序方式: 共有837条查询结果,搜索用时 15 毫秒
101.

Background

The World Health Organization (WHO) released new Child Growth Standards in 2006 to replace the current National Center for Health Statistics (NCHS) growth reference. We assessed how switching from the NCHS to the newly released WHO Growth Standards affects the estimated prevalence of wasting, underweight and stunting, and the pattern of risk factors identified.

Methodology/Principal Findings

Data were drawn from a village-informant driven Demographic Surveillance System in Northern Malawi. Children (n = 1328) were visited twice at 0–4 months and 11–15 months. Data were collected on the demographic and socio-economic environment of the child, health history, maternal and child anthropometry and child feeding practices. Weight-for-length, weight-for-age and length-for-age were derived in z-scores using the two growth references. In early infancy, prevalence estimates were 2.9, 6.1, and 8.5 fold higher for stunting, underweight, and wasting respectively using the WHO standards compared to NCHS reference (p<0.001 for all). At one year, prevalence estimates for wasting and stunting did not differ significantly according to reference used, but the prevalence of underweight was half that with the NCHS reference (p<0.001). Patterns of risk factors were similar with the two growth references for all outcomes at one year although the strength of association was higher with WHO standards.

Conclusions/Significance

Differences in prevalence estimates differed in magnitude but not direction from previous studies. The scale of these differences depends on the population''s nutritional status thus it should not be assumed a priori. The increase in estimated prevalence of wasting in early infancy has implications for feeding programs targeting lactating mothers and ante-natal multiple micronutrients supplementation to tackle small birth size. Risk factors identified using WHO standards remain comparable with findings based on the NCHS reference in similar settings. Further research should aim to identify whether the young infants additionally diagnosed as malnourished by this new standard are more appropriate targets for interventions than those identified with the NCHS reference.  相似文献   
102.
103.
Albania is a country of transition facing many challenges including the development and support of health and social services that will enhance the well-being of its population. Albania has one of the youngest populations in Europe and the young people face difficulties with lack of recognition and care of mental disorders, as well as violent and antisocial behaviours that may reflect violent environmental conditions and nutritional deficiencies leading to developmental problems. In this paper the behaviour of some Albanian adolescents was examined; it is probable that they are more at risk from psychological stress. For many of them the need to make a new start at a point in life at which all resources should be committed to distancing the world of childhood and starting to create a position, means a process of inevitable recession.  相似文献   
104.
Fungicides to control mycopathogens of commercial Agaricus bisporus, a mushroom cultivated for human consumption, are a major field of study, since these chemicals are toxic to both the host and its fungal parasites. The fungicide Prochloraz-Mn, used at its LD50 for A. bisporus, partially inhibited protein biosynthesis in the vegetative mycelial cell walls of this mushroom and caused significant changes in cell-wall polysaccharide structure, as deduced by methylation analysis and gas liquid chromatography-mass spectrometry (GLC-MS). Furthermore, the aggregated mycelial walls showed distinct alterations in their overall chemical composition following the administration of Prochloraz-Mn at the LD50 and the LD50 x1000. As expected, GLC-MS studies indicated that the latter dose caused more appreciable differences in polysaccharide structure. The decrease in mushroom crop yields obtained from industrial cultures treated with Prochloraz-Mn to control V. fungicola infection depended on the dose of the fungicide employed, whereas fruit-body morphology was only slightly affected at the highest Prochloraz-Mn concentration used.  相似文献   
105.
Three new dihydroxamic acids (HO(CH3)NCO-(CH2)2-CO-NH-(CH2)x-CON(CH3)OH where the x values are 4; 3 and 2, and the compounds are abbreviated as 2,4-DIHA, 2,3-DIHA and 2,2-DIHA), containing the peptide group in a certain position to one of the two functional groups and in different distances to the other one, were synthesized and their complexation with Fe(III), Mo(VI) and V(V) was studied by pH-potentiometric, spectrophotometric and in some cases by CV methods to evaluate the redox behaviour of the Fe(III) complexes and assess their potential biological activity as siderophore models. All these compounds are structural models for the natural siderophore, desferrioxamine B (DFB). The results were compared to those of the complexes of 2,5-DIHA having the same connecting chain structure and length as DFB has, and the effects of the length of the connecting chain on the co-ordination mode and on the stability of the complexes formed were evaluated.Very similar stability of the mono-chelated complexes formed with all these dihydroxamic acids was found. All the results obtained suggest that one dihydroxamic acid (even the 2,2-DIHA) is able to complete the four coordination sites of a MoO2 2+ core forming simple mononuclear complexes. Favoured monomeric structures of the bis-chelated complexes of these dihydroxamic acids are also suggested with V(V) having the smallest ionic radius among the three metal ions studied. In the case of iron(III), however, clear indication was obtained for the slightly different complexation behaviour of 2,2-DIHA. Namely, the formation of the mononuclear bis-chelated complex with this shortest ligand seems to have sufficient strain to induce the formation of bimetallic species such as [Fe(2,2-DIHA)2Fe)]2+.  相似文献   
106.
107.
108.
109.
110.
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