On Determinative Parameters of SDOF Systems in Elasto- plastic Earthquake Response

Parameters dominating elasto- plastic earthquake response of SDOF systems,relation between ground motion amplitude and elasto- plastic response of SDOF systems are presented in this paper.     

Cross-resistance and inheritance of resistance to Bacillus thuringiensis toxin Cry1Ac in diamondback moth (Plutella xylostella L) from lowland Malaysia

A field population of Plutella xylostella from Malaysia (SERD4) was divided into five sub-populations and four were selected (G2-G5) with the Bacillus thuringiensis insecticidal crystal (Cry) toxins Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da. Bioassay at G6 gave resistance ratios of 88, 5, 2 and 3 for Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da respectively compared with the unselected sub-population (UNSEL-SERD4). The Cry1Ac-selected population showed little cross-resistance to Cry1Ab, Cry1Ca and Cry1Da, (3-, 2- and 3-fold compared with UNSEL-SERD4), whereas the Cry1Ab-SEL sub-population showed marked cross-resistance to Cry1Ac (40-fold), much greater than Cry1Ab itself. In contrast, the Cry1Ca- and Cry1Da-SEL sub-population showed little if any cross-resistance to Cry1Ac and Cry1Ab. The mode of inheritance of resistance to Cry1Ac was examined in Cry1Ac-selected SERD4 by standard reciprocal crosses and back-crosses using a laboratory insecticide-susceptible population (ROTH). Logit regression analysis of F1 reciprocal crosses indicated that resistance to Cry1Ac was inherited as an incompletely dominant trait. At the highest dose of Cry1Ac tested, resistance was recessive, while at the lowest dose it was almost completely dominant. The F2 progeny from a back-cross of F1 progeny with ROTH were tested with a concentration of Cry1Ac that would kill 100% of ROTH. The mortality ranged between 50 and 95% in seven families of back-cross progeny, which indicated that more than one allele on separate loci were responsible for resistance to Cry1Ac.     

高寒珠芽蓼草甸植被生物量的季节动态特征

调查了甘肃省天祝县珠芽蓼高寒草甸,结果表明,调查草甸的主要植物有26种,隶属13科23属。其中珠芽蓼(0.148)为优势种,次优势种有乳白香青、球花蒿、线叶嵩草等。通过对珠芽蓼草甸群落组成和结构的季节动态的研究分析发现,地上植物量在整个生长季中表现为单峰曲线,地下植物量变化呈现“V”型曲线,环境因子是制约珠芽蓼草甸植物生长发育和植物量的主导因子。     

夏河甘加草原草地蝗虫优势种的确定及混合种群密度高峰值模型研究

通过对夏河甘加草原草地蝗虫种群存在度分析,确定该地区草地蝗虫优势种为狭翅雏蝗、小翅雏蝗、宽须蚁蝗、皱膝蝗(红翅皱膝蝗和鼓翅皱膝蝗)。对气象因子进行了主成分分析,提出了一年高峰值(yn)、产卵期的平均降水(x1)和温度(x2)、本年孵化期平均气温(x3)和降水(x3)为关键因子的非线性模型:yn+1=18.110 6+0.328 3x1+32.229 9/lnx2-182.237 3e-0.8x3+42.173 3x4e-x4)yn来描述混合种群的密度高峰值,且拟合度较高。     

晋西黄土丘陵边缘土石山区天然次生林群落β多样性研究

对晋西黄土丘陵边缘土石山区不同海拔高度木本植物物种丰富度以及各群落间β多样性特征进行了分析.结果表明,木本植物总物种丰富度随海拔高度的升高呈下降趋势,乔木种在海拔较高地段丰富度较大,灌木种则是在海拔较低地段丰富度较大.群落相异性指数Cody指数和Whittaker 指数多以相邻海拔群落间的指数值最小,群落间海拔差异越大指数值越大.而群落相似性指数Jaccard和Sorenson指数则表现出相反的变化规律,即随着群落间海拔差距的增大,指数值呈逐渐减小的趋势,相邻群落间的群落相似性指数值最大.     

白菜型油菜双显性核不育896AB恢复系基因型的鉴定

以白菜型油菜双显性核不育896AB为材料，采用成对兄妹交和相应可育株自交，验证显性不育基因的遗传;用恢复系与全不育系测交，测交一代与临保系复交，验证显性恢复基因的抑制作用，并区分F2代育性分离为3:1和13:3的遗传类型。经4个年度的研究认为，育性是由一对显性不育基因MSMS和一对显性可育基因RfRf互作控制，且显性可育基     

封育年限对典型草原大针茅无性系构件组成与生长的影响

研究不同封育年限对黄土高原大针茅(Stipa grandis)无性系构件结构组成和生长的影响,可为阐明无性系构件组成和资源分配提供一定基础。在黄土高原典型草原选取不同封育年限区(10和20年)和放牧地(对照)作为试验样地,采用整个无性系完整挖掘的方法进行大针茅无性系构件特征的研究。结果表明：1)与放牧相比,封育10年显著增加了大针茅无性系丛径、生殖枝高度和花序高度(P < 0.05),而封育20年则显著提高了大针茅无性系丛径、总枝数、生殖枝数、营养枝数、分蘖芽数、生殖枝高度、花序高度、地上总生物量、营养枝生物量和花序生物量(P < 0.05)。封育降低了大针茅生殖枝数、生殖枝高度、花序高度、地上总生物量、生殖枝生物量和花序生物量的变异系数。2)随封育年限增加,营养枝生物量比例明显提高,生殖枝生物量比例下降,但花序生物量比例基本不变。3)封育措施显著提高了营养株单株生物量(P < 0.05),但生殖株单株生物量和全体分枝单株生物量与放牧处理差异不显著(P > 0.05)。4)大针茅丛径与地上总生物量、生殖枝数、生殖枝生物量、花序生物量呈极显著正相关关系(P < 0.001),与营养枝生物量呈极显著正相关关系(P < 0.01),与总枝数呈显著正相关关系(P < 0.05)。而地上总生物量与生殖枝数、营养枝数、总枝数、营养枝生物量呈极显著正相关关系(P < 0.001),与分蘖芽数、生殖枝生物量和花序生物量呈极显著正相关关系(P < 0.01)。分蘖芽数与营养枝数、总枝数、营养枝生物量呈极显著正相关关系(P < 0.001),与地上总生物量呈极显著正相关关系(P < 0.01)。综上所述,短期封育提高了大针茅的生殖分配,使大针茅迅速成为群落优势种,而长期封育使大针茅更依靠无性繁殖进行种群更新。     

初植密度、间伐对杉木林分优势高生长过程的影响

初植密度、间伐对杉木林分优势高生长过程的影响＊洪玲霞关键词杉木优势高初植密度间伐立地质量是决定林分生长和收获的主要因素之一，在用材林经营与管理中，立地质量定义为“生长在某一地位上既定树种或林分类型林木的生产潜力”。以往的研究表明：许多树种的材积生产潜...     

武夷山不同森林类型土壤微生物分布状况的研究

对武夷山 3个不同森林类型的土壤微生物数量和类群组成变化进行了定位研究和观察。结果表明 :不同森林类型土壤异养微生物数量和组成比例都有明显差异 ,即使在同一森林类型条件下土壤剖面的不同层次都有其优势和特殊的细菌属、真菌属以及相对密度     

Genetics and mechanism of resistance to deltamethrin in a field population of Spodoptera litura (Lepidoptera: Noctuidae)

BACKGROUND: Spodoptera litura (F.) causes enormous losses in many economically important crops. The genetics of insecticide resistance has been extensively studied in several insect pests, but there is a lack of information on S. litura. Therefore, the genetics and mechanisms of the resistance of S. litura to deltamethrin were investigated. RESULTS: Bioassays at generation G1 gave resistance ratios of 9, 5, 41, 52 and 49 for deltamethrin, cypermethrin, profenofos, chlorpyrifos and triazofos respectively, when compared with the susceptible Lab-PK strain. Bioassays at G4 with a deltamethrin-selected population (Delta-SEL) showed that selection gave resistance ratios of 63 and 7 for deltamethrin when compared with the Lab-PK and UNSEL strains respectively. Cross-resistance to other insecticides tested was observed in the selected population. A notable feature of the Delta-SEL strain was that resistance to deltamethrin, cypermethrin, profenofos and chlorpyrifos did not decline over the course of five generations. Synergism tests with microsomal oxidase (MO) and esterase-specific inhibitors indicated that the deltamethrin resistance was associated with MO and, possibly, esterase activity. Reciprocal crosses between the Delta-SEL and Lab-PK strains indicated that resistance was autosomal and incompletely dominant. A direct test of monogenic inheritance suggested that resistance to deltamethrin was controlled by more than one locus. CONCLUSION: Stability and dominance of resistance and cross-resistance suggest that insecticides with different modes of action should be recommended to reduce pyrethroid selection pressure.