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排序方式: 共有953条查询结果,搜索用时 31 毫秒
61.
Gopalan C. Unnithan John F. Andersen Tomomi Hisano Eiichi Kuwano Ren Feyereisen 《Pest management science》1995,43(1):13-19
Seventeen substituted imidazoles were tested as inhibitors of juvenile hormone (JH) III synthesis by cockroach corpora allata in an in-vitro radio-chemical assay. Most of these 1,5-disubstituted imidazoles were highly potent, with IC50 values of less than 100nM. The compounds differed in their ability to cause an accumulation of the precursor methyl farnesoate in the glands. Four of the imidazoles were tested by topical application to previtellogenic adult females, and all caused a significant inhibition of JH synthesis and an accumulation of intraglandular methyl farnesoate for at least three days after treatment. Methyl farnesoate epoxidase activity of homogenates of corpora allata was inhibited by the compounds TH -14 and TH -27. This P450-dependent epoxidase activity was inhibited at less than 10 nM. The results show that the 1,5-disubstituted imidazoles are powerful inhibitors of the last step of juvenile synthesis in this cockroach. 相似文献
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Liu TX 《Pest management science》2003,59(8):904-912
Effects of a juvenile hormone analog, pyriproxyfen, on various developmental stadia of the onion thrips, Thrips tabaci Lindeman, were determined on cabbage leaves in the laboratory. Pyriproxyfen was applied at 0.064 or 0.128 g AI liter(-1) on leaves (residual contact-ingestion), thrips (direct contact) and leaf-thrips (residue contact-ingestion-direct contact). Pyriproxyfen did not have any significant lethal effects on thrips pupae in any treatment. Lethal effects on thrips larvae varied depending on application method and dosage. In the leaf and the leaf-thrips treatments, few larvae and pre-pupae molted to the next stage, and none developed to adults. In contrast, in the thrips-only treatment, pyriproxyfen did not show any significant lethal effects. The developmental times of larvae and pre-pupae were prolonged when larvae were treated with pyriproxyfen, and those of pre-pupae and pupae were shortened when pre-pupae and pupae were treated. The longevity and survival rates of thrips adults were generally shorter when they contacted and ingested pyriproxyfen-treated leaves than those in water control. Significantly fewer progeny (0.22-1.15 larvae per female) were produced by females that had fed on and been in contact with the pyriproxyfen-treated leaves than by those in the water control (11.94 larvae per female). However, the number of progeny produced by the thrips females increased significantly (3.32-7.28 larvae per female) when the females were transferred to untreated leaves after feeding on treated leaves for 5 days; the daily larval hatching pattern was similar to those in water control, indicating that female adults were able to produce viable eggs when untreated food was offered. 相似文献
64.
不同饲料蛋白质水平对吉富品系尼罗罗非鱼幼鱼生长和鱼体组成的影响 总被引:11,自引:0,他引:11
用3种不同蛋白含量(23.1%、37.6%和47.9%)的配合饲料投喂吉富品系尼罗罗非鱼幼鱼78d,结果显示,①随着饲料蛋白质含量从23.1%上升到47.9%,平均日增重从0.30g/d上升到0.74g/d,3组之间的日增重和体重有显著差异(P<0.05);饲料系数从1.53下降为0.98,3组之间的饲料系数有显著差异(P<0.05)。②不同的蛋白质水平对鱼体蛋白质和脂肪的含量有影响,各组之间差异显著(P<0.05),对灰分的影响差异不显著(P>0.05)。③蛋白含量为23.1%、37.6%和47.9%的配合饲料的成本分别为2.77元/kg、3.67元/kg、4.60元/kg。④初步认为蛋白含量为37.6%的配合饲料更适合吉富品系尼罗罗非鱼苗种培育的生产需要。 相似文献
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67.
杨树材性成熟龄模型的建立及树体内幼龄材的分布 总被引:3,自引:0,他引:3
以小叶杨和北京杨的材性测定值(导管分子长度或木纤维长度或导管腔径)作为因变量,以年轮数作为自变量,建立材性成熟非线性模型,以此为依据讨论成熟龄问题,并对幼龄材在树体内的分布进行分析。导管分子长度、木纤维长度和导管腔径的成熟龄模型为应用分段回归分析方法拟合的二次方程和定数函数结合的非线性方程,方程的决定系数在0 85 7~0 991之间,并在0 1 %水平上达到显著。以导管分子长度作为材性指标,应用这个非线性模型分析的结果表明:材性成熟龄及幼龄材半径因树种、立地的灌溉条件不同存在差异。无灌溉北京杨6~1 0年达到成熟,幼龄材半径为5 2mm左右;无灌溉小叶杨2 4~2 9年达到成熟,幼龄材的半径为90mm左右;灌溉小叶杨1 3~1 5年左右达到成熟,幼龄材的半径为85mm左右。 相似文献
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69.
Tekat Dwi Cahyono Wayan Darmawan Eka Novriyanti 《Wood material science & engineering》2020,15(3):155-162
ABSTRACTA study to determine the quality of laminated veneer lumber (LVL) from samama wood (Anthocephalus macrophyllus) was carried out. Samama is a fast-growing endemic wood in eastern Indonesia. Factorial of three factors in RAL design was used to investigate the influence of veneer thickness, juvenile proportion and veneer lay-up to the quality of the resulted samama LVL. The veneer thicknesses were 1.5 and 3.0?mm. Juvenile proportions were arranged in five levels, which were 100% of juvenile veneer, 100% of mature veneer and combination of both juvenile and mature with juvenile proportion of 14%, 43% and 71%. Two veneer lay-up used in this study were loose side met loose side and tight side met loose side. The result of the study showed various specific gravity of LVL by different proportions of juvenile. This factor also affected the other physical traits. Shear strength of the LVL was equal to the solid wood, yet MOE and MOR were affected by juvenile proportion and veneer lay-up. LVL developed from 100% of mature veneer exhibited the highest MOE and MOR, yet no significant difference was noted in MOE and MOR between LVL 100% of juvenile and other tested juvenile proportions. 相似文献
70.