共查询到20条相似文献，搜索用时 141 毫秒
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通过历期预测法和发育进度预测法对小云斑鳃金龟和粗绿彩丽金龟成、幼虫防治适期进行预测，小云斑鳃金龟成虫出土高峰期为7月16日至17日，幼虫防治适期为8月18日；粗绿彩丽金龟成虫出土高峰期为7月17～18日，幼虫防治适期为8月2～3日。粗绿彩丽金龟成虫出土高峰期，其卵巢发育指数为0．59。经用2年灯诱结果验证，与实际结果基本相符。同时采用logistic曲线对其化蛹进度进行了拟合。 相似文献
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黑绒鳃金龟（Ｍａｌａｄｅｒａｏｒｉｅｎｔａｌｓ）是哲盟地区重要苗圃害虫之一。１９９３～１９９５年在新开河林场、鲁北林场对黑绒鳃金龟进行较系统跟踪调查，掌握了黑绒鳃金龟在哲盟地区的生活史，并利用期距法进行发生期预报。 相似文献
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调查发现，大栗鳃金龟幼虫发生与环境因子关系密切，表现为无林地、未成林造林地重于有林地、灌木林地，郁闭度低的林分重于高的林分，疏松的土壤重于紧密土壤，坡面重于脊部与谷部，一些谷部及易形成积水的地方，虫口密度接近于零。指出气候变迁及生态环境恶性发展，是太子山浅山地带大栗鳃金龟危害逐渐严重的主要原因。 相似文献
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铜绿丽金龟是金龟甲类害虫中发生量最大、危害最严重的种类之一,其分布范围广,危害植物种类多。为了有效控制铜绿丽金龟的危害,使用太阳能板作为电源和303~580nm波段内的18种波长诱虫灯及全光谱对照灯林间诱杀成虫。筛选出诱杀铜绿丽金龟的最佳波长为400nm,最适灯诱时间为20:30-21:30,装水容器颜色应首选绿色。使用筛选出的最佳波长、灯诱时间和装水容器颜色组合开展林间诱杀,可以达到无公害手段压低虫口数量,以及安全有效、绿色环保地控制铜绿丽金龟的目的。 相似文献
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通过对黑龙江帽儿山地区金龟类访花甲虫种类的初步调查,结果表明,访花金龟共有15种,其中花金龟科有7种(46.67%),丽金龟科5种(33.33%),斑金龟科2种(13.33%),鳃金龟科1种(6.67%);优势种3种:短毛花金龟、小青花金龟和白星花金龟。金龟类访花优势种,主要访问的植物种类有:珍珠梅、深山唐松草、柳叶绣线菊、鸡树条荚蒾、蚊子草等。并对金龟类访花甲虫对花的选择特征进行了总结。 相似文献
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海拔1 000 m左右的亚高山年极端温度少、昼夜温差大、夏季冷凉,适合百合鳞茎生长,尤其是对剪切花后的种球复壮培育非常有利。对连续两年开花的3个百合品种各生长、开花指标的比较可见,百合植株高、茎粗、花径大小等指标在第2次开花时均未降低,且部分指标有所增长,没有出现明显退化,生产百合二茬花是完全可行的,由此可大幅度降低百合种球成本。 相似文献
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徒手切片法在进口材木材识别中的应用 总被引：2，自引：1，他引：2
从工具的制作、材料的处理、操作方法等方面介绍了采用徒手切片识别进口材的方法,并阐明其在高度木质化的木材中的应用与常规切片方法相比存在的优点、不足及注意事项,该方法适宜在时效性要求较高及珍贵或高档木制品的木材鉴定中应用. 相似文献
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清远市珍稀濒危植物资源和保护对策 总被引：1，自引：0，他引：1
１９９８年６月～２０００年６月,对清远市野生珍稀濒危植物资源进行了调查,发现野和珍稀濒危植物４１种,其中蕨类植物３科３属４种,裸子植物５科７属７种,被子植物２２科２８属３０种;国家一级保护稀有植物３种,国家二级保护渐危植物１２种,稀有植物１５种,广布种２种,国家三级保护渐危植物５种,稀有植物３种,省级保护稀有植物１种;另外还发现栽培的国家一级保护植物４种,二级保护植物２种。它们具有种类组成丰富,地 相似文献
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A. Krilov 《Wood Science and Technology》1976,10(3):199-208
Summary Examination of the bandsaw teeth (1) untreated, (2) swaged and (3) treated by thermal high-frequency surface hardening method has shown that their average microhardness is 473 DPN (<46 Rc), 502 DPN (<49 Rc) and 836 DPN (>62 Rc) respectively.Scanning electron microscopy revealed that no significant change occurred within the crystalline microstructure of untreated and swaged specimens. The high-frequency treated specimen, however, has shown a definite structural modification of a very finely grained martensitic type, extending from the apex for a distance of 0.24 mm.The relationship between DPN microhardness distribution throughout the bandsaw steel and the range of H.F. impulse times from 24/50 to 36/50 of a second was also investigated, and depth of the hardened zone determined.The optimal H.F. impulse time length corresponding to the optimal tooth hardness appears to lie between 32 and 33/50 of a second. Operating with 32/50 impulse time on a conventional 2.41 mm thick SANDVIK bandsaw with 0.73 mm side swage, it was found that the average hardness of a H.F. treated tooth apex is about 905 DPN (>64 Rc) to a depth of 415 m and in practical terms approaches the estimated optimum for high-speed cutting. 相似文献
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本文研究了山丘区钉螺壳体长宽鲜重体积,以及疫区壳体长宽与区域降水温度的关系。仁寿县钉螺鲜重0.0162 g(浮动在0.0065 g～0.0219 g之间),体积4.5894 mm3(3.12 mm3～5.6 mm3),长度5.156 mm(3.6 mm～6mm),宽度为2.668 mm(2.2 mm～3 mm)。分析表明,长度5 mm～6 mm为主体,宽度2.5 mm～3 mm为主体,钉螺宽度随着长度作缓慢而显著的增加;鲜重与群体的长度、宽度、体积无关。潮湿稻田生境钉螺长度明显最大,而干燥与湿润生境中次之,但宽度、体积、鲜重差异不明。疫区不同区域钉螺长度、宽度与降水量显著相关,而与温度无关,温度降水量比值与钉螺长度、宽度关系密切,表明钉螺大小有水分依赖性。在疫区内,可能水温匹配性共同塑造了钉螺的大小。 相似文献
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不同轮伐期和不同林分密度以及不同轮伐期组合和重复采收对大叶相思萌芽更新和林分产量影响的研究结果表明：①轮伐期对伐桩的萌芽力没有显著影响，但对萌芽林的生长有显著或极显著影响；林分密度对伐桩萌芽力和萌芽林生长均无显著影响。林分的材积和生物量总产量（种植后８ａ）随轮伐期的延长而减少。研究证明，大叶相思实生林萌芽更新的首采轮伐期以４ａ为最佳。②矮林作业能在一定程度上使大叶相思幼态化。在种植后５～６ａ内对这一树种进行第二次采伐的更新效果与第一次采伐的更新效果之间没有显著差异。对于以９ａ为一个经营期来说，以萌芽更新方式经营２代与３代其更新效果和林分总产量相当。为减少营林成本提高经济效益，建议经营两代即可，轮伐期组合以４＋５为最佳。 相似文献
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Two heuristic techniques, the genetic algorithm (GA) and Tabu search (TS), both with an embedded linear programming routine for earthwork allocation, were compared to a manually designed forest road profile. The manually designed road length was 345.7m and its average gradient was 14.1%. The best costs of the profiles designed by GA and TS, without changing the placement of control points, were less than that designed manually. The best cost found by GA was almost the same as the global optimum solution. While TS could not find a better solution than GA, it usually found a good solution in less time. It was not possible to search all alternatives by changing the placement of control points and find the global optimum solution within a reasonable time. However, it can be concluded from the results that both GA and TS found good solutions within a reasonable time. Since it is not possible to manually evaluate many alternatives, road designers should find heuristic techniques helpful for design of the road profile. Moreover, the effect of the number of control points on construction costs was examined. The results indicated that increasing the number of control points reduces the construction costs. However, driving safety and comfort might be decreased. 相似文献
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The occurrence of heart splitting during the crosscutting of logs was discussed in relation to the released strain on Eucalyptus spp. logs. The strains released in the longitudinal and tangential directions were measured by the strain-gauge method and were correlated with the length of the heart split measured on the same logs. There were differences in the longitudinal strain; however, no significant correlation was found with the diameter that could be converted to a mean annual increment (i.e., a relation with the growth rate). The initial splits expand with the time after felling. The longer the initial split, the longer is the length 1 week after felling. The split length was significantly smaller at the butt end of the first log of every tree than at the other end, but there were no significant differences between the split length at the top of the first logs and at either end of the second logs, although there were differences among individual trees. The length of the heart split correlated with the released strain near the pith, which was estimated using Kublers equation. The longitudinal released strain measured on the surface of logs is a good indicator of the heart splitting when crosscutting logs.Part of this paper was presented at the 52nd Annual Meeting of the Japan Wood Research Society 相似文献