二次三项式的因式分解     

A.M.STEINMETZ  S.CUNNIGHAM  施武杰 《数学教学通讯》1983,(4)

二次三项式ax~2+bx+c在给定的范围内如何进行因式分解,这是中学代数的一个重要内容。当a=1时,可用“十字相乘法”进行判断和分解,而当a≠1时,用上法就比较麻烦。本文推广了a=1时的“十字相乘法”,对于a≠1的情形也能较方便地进行判断和分解,  相似文献   

A profile of the oro-facial injuries in child physical abuse at a children's hospital     

Naidoo S 《Child abuse & neglect》2000,24(4):521-534

OBJECTIVE: The aim of the present study was to determine the head, face and neck injuries associated with child abuse cases in the Cape Peninsula, Cape Town. South Africa. METHOD: A retrospective, record-based analysis (n = 300) of non-accidental injuries at a Children's Hospital over a 5-year period (1992-1996) was carried out. RESULTS: The mean age of the sample was 4.75 years--54.3% were boys and 45.7% were girls. Most of the crimes were committed in the child's own home (88.7%). Crimes were reported by mothers (48.7%), grandmothers (11.7%) and day hospitals (13%). Ninety percent of the perpetrators were known to the victim. The majority of the perpetrators were male (79%)--20% the perpetrators were the mother's boyfriend; 36% the father or step father, and in 12% the mother was responsible. Thirty-five percent of perpetrators were under the influence of alcohol or drugs when they committed the offence: 64.7% of cases suffered serious injuries, 48.7% had to be hospitalized, four children were critically injured and died. The head, face, neck, and mouth were the sites of physical injury in 67% of the 300 cases reviewed. The face was the most frequently injured (41%) part of the body, with the cheek being the most common site for the injury. The range and diversity of the oro-facial injuries included skull fractures, subdural hematomas, retinal hemorrhages, bruises, burns, and lacerations. Injuries to the mouth included fractured teeth, avulsed teeth, lacerations to the lips, frenum, tongue, and jaw fractures. CONCLUSIONS: The main conclusions of this study were (i) under 2-year-old children were most at risk from abuse (36%); (ii) the number of the reported injuries to the oral cavity was extremely low (11%); and (iii) no dentists participated in the examination of any of the patients. Intra-oral injuries may be overlooked because of the medical examiner's unfamiliarity with the oral cavity. Oral health professionals should be consulted for diagnosis, advice and treatment.  相似文献   

Mediators of childhood sexual abuse and high-risk sex among men-who-have-sex-with-men     

Catania JA  Paul J  Osmond D  Folkman S  Pollack L  Canchola J  Chang J  Neilands T 《Child abuse & neglect》2008,32(10):925-940

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ADHD and reading disability in male adults: is there a connection?     

Samuelsson S  Lundberg I  Herkner B 《Journal of learning disabilities》2004,37(2):155-168

The present study examined the comorbidity between attention-deficit/hyperactivity disorder (ADHD) and reading disability (RD) in male adults. Participants were 120 men, of whom 24 were classified as having ADHD. The basis for the diagnosis was two self-report scales validated by interviews and background data. An extensive battery was used to assess phonological abilities and various aspects of reading skills. No differences were obtained between adults with and without ADHD on measures of either phonological processing skills or word decoding, indicating a low comorbidity with RD. This finding was valid even when different criteria were used to diagnose RD. However, the two groups differed in reading comprehension, with individuals with ADHD performing poorly in tests of reading comprehension. These results are compatible with the view that reading comprehension involves many of the higher cognitive control functions assumed to be impaired in ADHD. However, these attentional control functions are not critical to word recognition, which is determined by a more encapsulated phonological processing module. The pattern of associations between ADHD and RD observed in the present study is explained with reference to the differential attentional demands of the two aspects of reading.  相似文献   

你见过那棵树吗?     

罗伯特·S·凯弗 《当代学生》2005,(6)

关于那棵树,最初是我的邻居加根太太告诉我的。那天,我坐在后院欣赏着十月的暮色,加根太太过来问我:“你见过那棵树吗?”她接着说:“就是那边下去拐角的一棵,五颜六色的,漂亮极了,好多车路过都停下来看,你该去看看才是。”  相似文献   

Childbirth educators, doulas, nurses, and women respond to the six care practices for normal birth          下载免费PDF全文

Curl M  Davies R  Lothian S  Pascali-Bonaro D  Scaer RM  Walsh A 《The Journal of perinatal education》2004,13(2):42-50

This collection of commentaries by childbirth educators, doulas, a labor and delivery nurse, and a woman preparing for the birth of her second baby provide an overall response to all six of Lamaze International's care practice papers that promote normal birth: Labor Begins on Its Own; Freedom of Movement throughout Labor; Continuous Labor Support; No Routine Interventions; Non-Supine (e.g., Upright or Side-Lying) Positions for Birth; and No Separation of Mother and Baby with Unlimited Opportunity for Breastfeeding. Strategies for using the position papers to facilitate learning in childbirth classes and for helping expectant parents access and understand research are presented. The commentaries describe the value of the position papers as a catalyst for professional growth, a foundation for creating change, a way to encourage reflection among professionals and women planning for the births of their babies, and an inspiration for everyone who advocates normal birth.  相似文献   

塞瓦定理与梅涅劳斯定理的联合推广     

M.S.克拉姆金  刘安迪  李学武 《中等数学》1993,(2)

译注:该文引用了两个不难理解的新概念(广义欧氏平面(这是射影几何中的概念),与重心坐标),而使有关证明相当简洁,有关定理的结果及应用实例都很有启发性。塞瓦定理与梅涅劳斯定理在讨论诸线的共点与诸点的共线方面应用很广,其结果早已从三角形推广到多边形及空间图形。此外,这两个定理由于具有对偶性还可以相互导出。本文仅就三角形的情形给出一个推广,使  相似文献   

Chilli anthracnose disease caused by Colletotrichum species     

Than PP  Prihastuti H  Phoulivong S  Taylor PW  Hyde KD 《Journal of Zhejiang University. Science. B》2008,9(10):764-778

Anthracnose disease is one of the major economic constraints to chilli production worldwide, especially in tropical and subtropical regions. Accurate taxonomic information is necessary for effective disease control management. In the Colletotrichum patho-system, different Colletotrichum species can be associated with anthracnose of the same host. Little information is known concerning the interactions of the species associated with the chilli anthracnose although several Colletotrichum species have been reported as causal agents of chilli anthracnose disease worldwide. The ambiguous taxonomic status of Colletotrichum species has resulted in inaccurate identification which may cause practical problems in plant breeding and disease management. Although the management and control of anthracnose disease are still being extensively researched, commercial cultivars of Capsicum annuum that are resistant to the pathogens that cause chilli anthracnose have not yet been developed. This paper reviews the causal agents of chilli anthracnose, the disease cycle, conventional methods in identification of the pathogen and molecular approaches that have been used for the identification of Colletotrichum species. Pathogenetic variation and population structure of the causal agents of chilli anthracnose along with the current taxonomic status of Colletotrichum species are discussed. Future developments leading to the disease management strategies are suggested.   相似文献   

夏山教育与一般教育的比较     

A.S.尼尔 《快乐阅读》2012,(32):76-77

我相信生命的意义在于追求幸福,在于寻找兴趣。教育是为人生做的准备,我们这样的文化不算成功,我们的教育、政治和经济都在引导我们走上战争的道路。我们的医药无法完全征服疾病,我们的宗教没有消除高利贷和抢劫,我们鼓吹的人道主义依然默许野蛮的打猎。时代的进步只是机械的  相似文献   

REPORT OF COMMITTEE ON INCORPORATION     

Tye MM  Biethan S  Ballard JF  Hibbard RM 《Bulletin of the Medical Library Association》1932,21(1):33

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