用计算机模拟农药在土壤中的移动和降解   总被引：1，自引：0，他引：1  

陈秋方  A.E.Evans  P.H.Nicholls  G.G.Briggs 《土壤学报》1986,23(4):375-381

本文应用CALF模式,用计算机模拟杀螨剂NC13292在淤积粘壤土中的移动和降解并与田间的实际测定进行比较,结果表明:当仅用吸附系数进行模拟时,经过一段时间以后,模拟的农药移动速度往往大于田间实际移动速度.它暗示农药在土壤中的移动可能存在着两个过程.一是农药在土壤固相与土壤水相之间的分配过程.这一过程对于农药在土壤中的移动起主导作用.二是扩散过程.只有在团粒结构或粘性土壤中,特别是对于极性农药,这一过程才相当重要,在应用吸附系数的同时,再引入一个经验扩散比率常数(0.0125/天),则NC13292在该土壤中移动速度的模拟结果与田间实际测定非常接近.  相似文献   

Predator control for protecting kaki (Himantopus novaezelandiae)—lessons from 20 years of management     

Rachel J KeedwellRichard F Maloney  Dave P Murray 《Biological conservation》2002,105(3):369-374

In New Zealand, the endemic kaki or black stilt (Himantopus novaezelandiae) has been the focus of intensive conservation management for the past 20 years. Threatened by predation and habitat loss, the population fell to as low as 23 birds before management was implemented to reverse the decline. Predator trapping has been one form of management intervention in the wild, yet despite 20 years of control, there is only limited evidence to suggest that predator trapping is beneficial for the survival of kaki. Lack of adequate experimental design and understanding of the predator-prey dynamics in the system in which kaki live appear to be the main reasons why the benefits of predator control are not consistently clear. An adaptive management approach would have provided more information on the efficacy of predator trapping and increased understanding of the inter-relationships between kaki survival and predator abundance.  相似文献   

The availability for the rat of methionine and cystine contained in dry bean seed (Phaseolus vulgaris)     

R J Evans  D H Bauer  K A Sisak  P A Ryan 《Journal of agricultural and food chemistry》1974,22(1):130-133

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Molecular genetics of race non-specific rust resistance in wheat   总被引：1，自引：0，他引：1  

Evans S. Lagudah 《Euphytica》2011,179(1):81-91

Over 150 resistance genes that confer resistance to either leaf rust, stripe rust or stem rust have been catalogued in wheat or introgressed into wheat from related species. A few of these genes from the ‘slow-rusting’ adult plant resistance (APR) class confer partial resistance in a race non-specific manner to one or multiple rust diseases. The recent cloning of two of these genes, Lr34/Yr18, a dual APR for leaf rust and stripe rust, and Yr36, a stripe rust APR gene, showed that they differ from other classes of plant resistance genes. Currently, seven Lr34/Yr18 haplotypes have been identified from sequencing the encoding ATP Binding Cassette transporter gene from diverse wheat germplasm of which one haplotype is commonly associated with the resistance phenotype. The paucity of well characterised APR genes, particularly for stem rust, calls for a focused effort in developing critical genetic stocks to delineate quantitative trait loci, construct specific BAC libraries for targeted APR genes to facilitate robust marker development for breeding applications, and the eventual cloning of the encoding genes.  相似文献   

OVARIAN CHANGES DURING PREGNANCY IN THE RAT     

Swezy O  Evans HM 《Science (New York, N.Y.)》1930,71(1828):46

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The elemental composition of asteroid 433 eros: results of the NEAR-shoemaker X-ray spectrometer     

Trombka JI  Squyres SW  Bruckner J  Boynton WV  Reedy RC  McCoy TJ  Gorenstein P  Evans LG  Arnold JR  Starr RD  Nittler LR  Murphy ME  Mikheeva I  McNutt RL  McClanahan TP  McCartney E  Goldsten JO  Gold RE  Floyd SR  Clark PE  Burbine TH  Bhangoo JS  Bailey SH  Petaev M 《Science (New York, N.Y.)》2000,289(5487):2101-2105

We report major element composition ratios for regions of the asteroid 433 Eros imaged during two solar flares and quiet sun conditions during the period of May to July 2000. Low aluminum abundances for all regions argue against global differentiation of Eros. Magnesium/silicon, aluminum/silicon, calcium/silicon, and iron/silicon ratios are best interpreted as a relatively primitive, chondritic composition. Marked depletions in sulfur and possible aluminum and calcium depletions, relative to ordinary chondrites, may represent signatures of limited partial melting or impact volatilization.  相似文献   

Tidal Growth Increments in the Cockle Clinocardium nuttalli     

Evans JW 《Science (New York, N.Y.)》1972,176(4033):416-417

Sets of growth lines in the shell of Clinocardium nuttalli are extinguished every 13 or 14 increments only to be replaced by other sets, half an increment out of phase with the first. This can be explained only by assuming that the lines are deposited during periods of exposure at low tide. The average duration of an increment is 24 hours and 50 minutes.  相似文献   

Ecosystem as the Basic Unit in Ecology     

Evans FC 《Science (New York, N.Y.)》1956,123(3208):1127-1128

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Planetary radio astronomy observations from voyager 2 near saturn     

Warwick JW  Evans DR  Romig JH  Alexander JK  Desch MD  Kaiser ML  Aubier M  Leblanc Y  Lecacheux A  Pedersen BM 《Science (New York, N.Y.)》1982,215(4532):582-587

Planetary radio astronomy measurements obtained by Voyager 2 near Saturn have added further evidence that Saturnian kilometric radiation is emitted by a strong dayside source at auroral latitudes in the northern hemisphere and by a weaker source at complementary latitudes in the southern hemisphere. These emissions are variable because of Saturn's rotation and, on longer time scales, probably because of influences of the solar wind and Dione. The electrostatic discharge bursts first discovered by Voyager 1 and attributed to emissions from the B ring were again observed with the same broadband spectral properties and an episodic recurrence period of about 10 hours, but their occurrence frequency was only about 30 percent of that detected by Voyager 1. While crossing the ring plane at a distance of 2.88 Saturn radii, the spacecraft detected an intense noise event extending to above 1 megahertz and lasting about 150 seconds. The event is interpreted to be a consequence of the impact, vaporization, and ionization of charged, micrometer-size G ring particles distributed over a vertical thickness of about 1500 kilometers.  相似文献   

A predator unmasked: life cycle of Bdellovibrio bacteriovorus from a genomic perspective     

Rendulic S  Jagtap P  Rosinus A  Eppinger M  Baar C  Lanz C  Keller H  Lambert C  Evans KJ  Goesmann A  Meyer F  Sockett RE  Schuster SC 《Science (New York, N.Y.)》2004,303(5658):689-692

Predatory bacteria remain molecularly enigmatic, despite their presence in many microbial communities. Here we report the complete genome of Bdellovibrio bacteriovorus HD100, a predatory Gram-negative bacterium that invades and consumes other Gram-negative bacteria. Its surprisingly large genome shows no evidence of recent gene transfer from its prey. A plethora of paralogous gene families coding for enzymes, such as hydrolases and transporters, are used throughout the life cycle of B. bacteriovorus for prey entry, prey killing, and the uptake of complex molecules.  相似文献