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321.
通过实验的方法,将"发现"式的学习理论应用于教学实践。实验表明:实验班的学生在篮球专项技术、操作思维能力、身体素质及运用篮球知识和技术解决问题的能力等方面明显高于对照班。"指导式发现教学"可使初学者尽快地掌握正确的技术动作,缩短技能形成所需要的时间;可使学生在学习技术动作的同时,深入系统地掌握理论知识;可培养学生运用知识进行观察、分析、判断能力,养成主动的学习习惯。 相似文献
322.
哈萨克女作家哈依霞.塔巴热克和叶尔克西.胡尔曼别克是运用双语创作、双语思维、具有多元文化视角的优秀哈萨克女作家。在本民族与汉民族文化心理态势重铸的选择中,她们的创作既有融合、认同,又有矛盾、困惑;既充分展示了哈萨克民族文化的神韵和个性,又广采博收,汲取人类多元文化的有益养分,具有超越民族界限的哲理思考;她们的创作实绩证明了多元文化视角对于弘扬民族文化、发展民族文学有着重要意义。在对她们文学创作多元视角文化优势的充分肯定的基础上(见上篇),本文着重通过对她们文本的解读,阐释少数民族作家双语创作的文化困惑及其意义。 相似文献
323.
Recent temperature increase recorded in an ice core in the source region of Yangtze River 总被引:3,自引:4,他引:3
KANG ShiChang ZHANG YongJun QIN DaHe REN JiaWen ZHANG QiangGong Bjorn GRIGHOLM Paul A. MAYEWSKI 《科学通报(英文版)》2007,52(6):825-831
Interests on climate change in the source region of Yangtze River have been raised since it is a region with the greatest warming over the Tibetan Plateau (TP). A 70-year history of precipitation δ~(18)O has been recovered using an ice core record retrieved in a plat portion of the firn area in the Guoqu Glacier (33°34′37.8″N, 91°10′35.3″E, 5720 m a.s.l.), Mt. Geladaindong (the source region of Yangtze River), in November, 2005. By using a significant positive relationship between ice core δ~(18)O record and summer air temperature (July to September) from the nearby meteorological stations, a history of summer air temperature has been reconstructed for the last 70 years. Summer temperature was relatively low in 1940s and high in 1950s to the middle of 1960s. The lowest temperature occurred in the middle of 1970s. Temperature was low in 1980s and dramatically increased since 1990s, keeping the trend to the begin-ning of the 21st century. The warming rate recorded in the ice core with 0.5℃/10 a since 1970s is much higher that that in the central TP and the Northern Hemisphere (NH), and it becomes 1.1℃/10 a since 1990s which is also higher than these from the central TP and the NH, reflecting an accelerated warm-ing and a more sensitive response to global warming in the high elevation region. 相似文献
324.
Qiu Baoli Susan A. Coats Ren Shunxiang Ali M. Idris Xu Caixia Judith K. Brown 《自然科学进展》2007,17(6):645-654
Phylogenetic relationships for Bemisia tabaci were reconstructed by analysis of a ~780 bp fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene with an emphasis on geographic range and distribution among eight eudicot plant families that are common hosts of B. tabaci worldwide to elucidate key phylogeographic linkages between populations extant in China (n=31) and India (n=34). Bootstrap values for the Maximum Parsimony tree were highly robust for all major nodes involving the major Asian clade, subgroups, and sister groups within, at 92%—100%. Between-clade distances for the Southeast Asia and three other major clades, e.g. from sub-Sahara Africa, North Africa-Mediterranean, and the Americas, were approximately >16% divergent. Two major Asian subgroups (I, II) were resolved, which represented populations indigenous to the region, comprising two (I a, I b) and five (II a—e) sister groups, respectively, which diverged by 11%. Two distinct populations from sunflower in Hyderabad grouped separately within the two Asian subgroups. All other populations grouped uniquely within Asian subgroup II or I. The “B” biotype was identified in 23 collections from China at 97.3%—99.5% nucleotide identity with “B” biotype reference sequences; it was not identified in collections from India. The majority of haplotypes were associated with 3—4 plant families, with one exception that for sister group IId (sesame, India), it might be monophagous. Thus, B. tabaci from the southeastern and near eastern regions of the Asian continent comprise of a large number of ancestral, richly divergent, mostly polyphagous populations. This region is therefore hypothesized to constitute an important Old World center of diversification for the B. tabaci complex, together with sub-Saharan Africa. 相似文献
325.
326.
太原是一座具有2500年历史的古城,历史文化遗产众多,旅游资源丰富,但许多旅游资源还没有转化为旅游产品。太原市的旅游发展具有特殊的区位优势,主要表现在:可开发的客源市场充足;基础设施和环境条件日臻完善;地处山西省疆土的中央,以太原为中心2h-3h路程的“大太原”旅游格局逐渐形成,太原又位于北京与西安两大国际旅游城市连接线的中点,形成北京-山西-陕西旅游黄金通道,太原气候条件优越,文章利用温湿指数和风效指数计算分析了太原全年旅游气候舒适度,得到结论:可以开展旅游的天数可达270d,适宜旅游天数210d,适宜于旅游、休闲、渡假、疗养天数为180d。 相似文献
327.
用化学还原法合成了Fe(Pd)P合金颗粒,详细考察了反应温度、溶液的pH值、添加剂、反应物料比以及引发剂等因素对反应速度、产率以及磷含量的影响,选择了适宜的合成条件. 相似文献
328.
随着计算机技术在企业中的广泛应用,企业数据信息的安全问题日渐突出,并受到高度重视.根据企业信息化系统现在的运行情况、企业数据库受到的种种危害以及企业数据信息量大的特点,针对企业信息系统用户多而且访问权限复杂的特点安全要求,应用一些数据库的安全技术、备份技术、恢复技术,指定企业数据库安全的策略,从而维护企业信息的安全. 相似文献
329.
New fossil elaterid (Coleoptera: Polyphaga: Elateridae) from Yixian Formation of western Liaoning, China 总被引:4,自引:0,他引:4
A new species of the elaterid genus Cryptocoelus Dolin and Nel, 2002 from the Late Jurassic to Early Cretaceous Yixian Formation in the western Liaoning, China is described. Diagnosis of the genus is revised, and the systematic position of the genus is briefly discussed. Because the elaterids originated in the Early to Mid-Jurassic, this new material from the Late Jurassic-Early Cretaceous will enhance our understanding of the transition between ancient elaterids and extant ones, bridge the gap of cryptic relationships between the Mesozoic cupedids and elaterids, and expand our knowledge of their evolutionary history. 相似文献
330.
Xie Aihong Qin Dahe Ren Jiawen Qin Xiang Xiao Cunde Hou Shugui Kang Shichang Yang Xingguo Jiang Youyan 《自然科学进展(英文版)》2007,17(7):828-837
Mount Everest,the highest point on the Earth is often referred to as the earth's third pole as such the place is relatively inaccessible and little is known about its meteorology.In April 2005,an automatic weather station was installed at the mountain's North Col(6523 m a.s.l.).According to the observational 10-minute mean and daily records,the meteorological characteristics were analyzed. All the meteorological elements displayed obvious diurnal variations during May 1 to July 22,2005.The monthly variation of daily meteo- rological elements on Mount Everest coincided with that on Dingri,the closest routine meteorological station,with the high correlation co- efficients of 0.928,0.877,0.682,0.755,0.826 and 0.676(n=83,p<0.001)for mean temperature,minimum temperature,max- imum temperature,relative humidity,pressure and wind speed,respectively.Furthermore,the vertical mean gradient of temperature was above 0.6℃/100 m,especially for the daily maximum temperature.Most weather events on Mount Everest prominently appeared on the same day as those on Dingri,especially those from daily mean pressure,temperature and relative humidity with the cross-correlation coeffi- cients of 0.673,0.485 and 0.487(n=83,p<0.001),respectively.Some other weather events on Mount Everest lagged one-day be- hind those on Dingri.Furthermore,forecasting of the weather events on Mount Everest from pressure on Dingri was more reliable than those from the other meteorological elements.The conclusions are much important for research on meteorology and climate changes in the region. 相似文献