论罚球在现代篮球比赛中的地位及训练方法     

王建萍 《山东饲料》2008,(12)

罚球在篮球比赛上可算为最容易的得分方式可,然而,在一些重要赛事上,常见有些平时投篮很准的运动员也会发球失常。本问通过对篮球比赛罚球命中率失常的原因进行分析,指出应该有针对性的、有计划的对运动员进行集中注意力的"脱敏"训练。  相似文献   

降雨量对广西地区白蜡虫死亡及其种虫白蜡产量的影响^*   总被引：3，自引：1，他引：3       下载免费PDF全文

岑明  计鸿贤  林发源 《林业科学研究》1993,6(2):194-199

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火炬松材性变异规律的初步研究   总被引：4，自引：0，他引：4  

宋云民  黄永利 《林业科学》1995,31(4):346-352

对生长于广西南宁地区相同环境下来自美国的１８个种源１０年生火炬松的材性进行了研究。包括：材笥的种源变异。材性的地理变异模式及其与原产地气候因子的相互关系，材性因子间及其与生长因子、形态因子的相关分析。  相似文献   

石竹出笋退笋规律研究   总被引：7，自引：0，他引：7  

郑明生 《福建林业科技》2001,28(3):86-88

对石竹出笋退笋规律的研究表明 ,石竹出笋时间始于 5月 1日左右 ,历时约 36d ,出笋初期出笋少 (持续时间 12d左右 ,占 11 1% ) ,盛期出笋数较多 (持续时间 18d ,占 83 9% ) ,末期出笋数迅速下降 (持续时间 6d ,出笋占 5 0 % ) ,初期出土石竹笋退笋少 ,以后退笋率不断增加 ,但末期退笋率又有所下降。随着笋期的推移 ,退笋高度不断增加 ,退笋生长时间缩短。  相似文献   

Extractives relating to heartwood color changes in sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) by a combination of smoke-heating and UV radiation exposure     

F.?Ishiguri  S.?Maruyama  K.?Takahashi  Z.?Abe  S.?Yokota  M.?Andoh  N.?YoshizawaEmail author 《Journal of Wood Science》2003,49(2):135-139

 Sugi green logs with red or black heartwood were smoke-heated, and the changes in the color of the heartwood after ultraviolet (UV) (λ = 365 nm) radiation exposure were then observed. After UV radiation exposure, the redness and yellowness increased in both the red and black heartwoods, whereas the brightness decreased. In the black heartwood, the resulting color turned from yellowish white to reddish brown. Reddening in black heartwood after exposure to a combination of smoke heating and UV radiation is thought to be due to a decrease in brightness and an increase in both redness and yellowness. However, the degree of change in heartwood color by UV radiation exposure was not greatly affected by smoke-heating treatments of various lengths. When methanol extracts were fractionated and exposed to UV radiation, the yellowness increased in the n-hexane-soluble portion and the redness increased in the acetone-soluble fractions from the n-hexane-insoluble portion. These results suggest that the n-hexane-soluble fraction contains the substances that allow heartwood color to change to yellow after UV radiation exposure, and the acetone-soluble-fraction from the n-hexane-insoluble portion contains the substances that allow it to change to red. Received: November 14, 2001 / Accepted: June 3, 2002 Acknowledgment This research was supported in part by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science. This study was presented in part at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001 Correspondence to:N. Yoshizawa  相似文献   

Seed Maturation Indicators in Pyracantha crenulata Roxb. in Kumaun Central Himalaya     

Shruti Shah  Bhawna Tewari  Swati Bisht  Ashish Tewari 《New Forests》2006,32(1):1-7

Fruits of Pyracantha crenulata were collected from two locations varying by approximately 550 m in elevation from south aspect for assessing seed maturation indicators. The mean seed size (length×diameter) across the collection dates varied between 1.61 ± 0.7 and 4.93 ± 0.06 mm² across both the locations. The seed moisture content negatively correlated with germination. The change in fruit colour from dark green to light orange, the range of fruit moisture content (30.43% ± 0.06 to 36.10% ± 0.25) and the seed moisture content between 68.8% ± 0.68 and 71.6 ± 0.62 coincided with maximum germination and appear to be major indicators of seed maturation in Pyracantha crenulata.  相似文献   

香椿种子的发芽率与采种方法及贮藏技术的相关性研究   总被引：2，自引：1，他引：2  

史兆庆 《山西林业科技》2001,(4):19-21

传统的采种方法与贮藏技术，导致香椿种子发芽率低、不耐贮藏、极大地影响了香椿的生产和经营。作者通过近年的试验研究，总结出一套香椿种子正确的采种与贮藏技术，可确保香椿种子的以较高的发芽率，常年供应市场需求。  相似文献   

永嘉早香柚授粉及保水措施试验   总被引：5，自引：0，他引：5  

徐文荣  陈秋夏  陈少华  郭秀珠  黄品湖  李鍔 《浙江林业科技》2002,22(4):49-52

为探索永嘉早香柚的低产原因和降低内裂果措施。进行了授粉和保水措施试验，结果表明，通过授粉能有效提高永嘉早香柚的座果率；授粉配合保水措施能有效降低永嘉早香柚的内裂果和裂瓣率。  相似文献   

不同种源泡桐种子场圃发芽率差异分析     

范新  杨秀玲  刘震  刘艳萍 《河南林业科技》2006,26(4):6-8

为了探讨各种源泡桐生长适应情况,采用不同种源泡桐种子育苗,观察研究了其场圃发芽特性。结果表明:对于毛泡桐的种子潍坊种源发芽率最高,平均发芽时间与同种相比也较短;对于兰考泡桐的种子检验指标都显示出了宝鸡种源的优势;白花泡桐的种子的试验表明,福州种源的发芽率最高,但平均发芽时间也是最长,而南平种源的发芽率和发芽势仅次于福州种源,但它的平均发芽时间却比福州种源短的多,因此应考虑南平种源的栽培选育。  相似文献   

林木调查因子生长率之间的关系研究     

吕勇  安里練雄  周春华  李典军 《中南林业调查规划》2003,22(1):28-30

以湖南省会同县的杉木为例，研究了直径生长率与树高生长率、材积生长率的相关关系。采用生长量修正法建立了杉木单木竞争生长量模型，回归拟合出树高生长指数κ的相关模型作为中介模型，推手出了杉木直径生长率、树高生长率、材积生长率的预估模型。  相似文献