排序方式： 共有47条查询结果，搜索用时 15 毫秒
1.
The purpose of this investigation was to describe the morphological parameters that characterize elite age group divers. Comparisons are made to normative age group data from the Coquitlam Growth Study and the constancy of important characteristics from age group to age group is examined. Data were collected on 27 male and 28 female elite divers who participated in the 1990 North American Age Group Diving Championships. Body build, body composition and skinfold corrected diameters were determined from 36 anthropometric parameters and analysed by ANOVA, t-test and Phantom z-scores procedures. All age groups except the 14- to 15-year-old males were significantly (P < or = 0.05) shorter than their norms but recorded higher androgyny index values. The estimated relative muscle mass increased significantly (P < or = 0.05) with age for males at all ages (40.8-46.3%). The 16- to 18-year-old females had a significantly (P < or = 0.05) larger relative muscle component compared to the younger age groups (40.1-38.4%). When normalized for height, active tissue development of the extremities was comparable between the sexes except in the forearm. The results indicate that at all age levels short stature is an important characteristic for divers. Analysis of regional active tissue development provides further insight into sport-specific prerequisites for success at elite levels. 相似文献
2.
金玉 《贵州教育学院学报》2000,11(2):68-70
针对数学教学中如何加强学生学习方法指导提出了看法和意见并应用于具体的实践中,促使学习从“学会”数学到“会学”数学的转变,有效地提高了教学质量,最终使学生取得良好的成绩,对其它学科的学法指导也有一定指导意义。 相似文献
3.
4.
亚洲玉米螟幼虫转移规律及防治适期研究 总被引：6，自引：0，他引：6
通过对亚洲玉米螟幼虫转移规律及防治适期的研究,明确了在心叶末期前９０％的幼虫集中在雄穗中,抽穗后才分散转移,大多数幼虫分散到中部和穗部,占总虫数的６０％左右．经不同时期防治试验表明,在春、夏、秋玉米连续种植,玉米螟为害严重的地区,在心叶末期防治的基础上,在吐丝期再防治一次,才能有效地减少虫量,提高产量 相似文献
5.
Associations Between Sexting Behaviors and Sexual Behaviors Among Mobile Phone‐Owning Teens in Los Angeles 
下载免费PDF全文
下载免费PDF全文 Eric Rice Jaih Craddock Mary Hemler Joshua Rusow Aaron Plant Jorge Montoya Timothy Kordic 《Child development》2018,89(1):110-117
The implications of teen sexting for healthy development continue to concern parents, academics, and the general public. Using a probability sample of high school students (N = 1,208) aged 12–18, the prevalence of sexting, associations with sexting, and associations between sexing and sexual activity were assessed. Seventeen percent both sent and received sexts, and 24% only received sexts. Sending and receiving sexts were positively associated with each other and both behaviors were associated with having peers who sext. Lifetime reports of sexual intercourse, anal sex, oral sex, and recent unprotected sex were positively associated with reports of texting 300 or more times per day, only receiving sexts, and both sending and receiving sexts. 相似文献
6.
疏筋壮骨功提高人体机能的医学观察 总被引：1，自引：0，他引：1
对28例练习疏筋壮骨功者3个月前后的部分指标进行了测定,论证了提高人体有关系统机能的方法及原因,为指导人们更好地练功提供了参考依据。 相似文献
7.
Denmark, Sweden, Norway, Finland and Iceland: these are the Nordic countries, the Five Swans. This article covers main Nordic
guidance issues with characteristic examples from the various countries under the headings of Professionalisation, Guidance
Policies, Activities, Staff and professional background, Linkages, and Materials and ICT.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Quality assurance (QA) and Evidence in career guidance are increasingly seen as an indispensable part of explaining and even legitimising career guidance activities and policies. It is no longer sufficient to assume that career guidance or career education has an impact. This has to be demonstrated. This paper provides an overview of how and why QA approaches are featuring ever more significantly on the agenda of many European Countries. A particular focus is the link between particular quantitatively oriented QA approaches and the effects that this has upon guidance policies and practices. The paper concludes by raising some of the wider QA issues that need to be addressed. 相似文献
9.
Peter Plant Mar��a Jos�� L��pez-S��nchez 《International Journal for Educational and Vocational Guidance》2011,11(1):3-15
Guidance has a role to play in helping older workers to lead meaningful and fruitful lives; inside, outside, on the edge of
the labour market, or in voluntary work with examples from two very different European countries: Denmark and Spain. This
paper aims to draw attention to older workers guidance from an economic policy approach. It will be demonstrated that there
is a need for more policy making for older workers’ guidance in both countries. 相似文献
10.
天然白桦种苗光合作用日进程 总被引：6，自引：0，他引：6
本研究采用最先进的光合作用测定系统ＬＩ－６４００测定多功能树种白桦种苗的光合作用．天然白桦种苗光合速率日进程表现为单峰曲线,在下午１４： ００时达到最高峰（１０．５３μｍｏｌＣＯ２ｍ－２ｓ－１）,．其光合作用不存在“午休现象”．在１４：００时,白桦的气孔限制值（０.３１７２）和水分饱和亏缺（２．４６ｋＰａ）分别达到最大值,此时其水分利用效率较高,在中午１２：００时水分利用率达到最大值（２．９７ ｕｍｏｌＣＯ２ｍ－２ｓ－１ｍｍＨ２Ｏｍ－２ｓ－１）．在早上８：００,白桦获得一天中最大的表观量子效率;其蒸腾速率在下午１４： ００时最大（４．８２ｍｍＨ２Ｏｍ－２ｓ－１）．在光合速率的日进程中,白桦高光合速率值持续至少 ４个小时．这使得白桦的光合作用量得以有效累积,进而为其生长创造了有利条件． 相似文献