Evidence for retrograde lithospheric subduction on venus

Annular moats and outer rises around large Venus coronae such as Artemis, Latona, and Eithinoha are similar in arcuate planform and topography to the trenches and outer rises of terrestrial subduction zones. On Earth, trenches and outer rises are modeled as the flexural response of a thin elastic lithosphere to the bending moment of the subducted slab; this lithospheric flexure model also accounts for the trenches and outer rises outboard of the major coronae on Venus. Accordingly, it is proposed that retrograde lithospheric subduction may be occurring on the margins of the large Venus coronae while compensating back-arc extension is occurring in the expanding coronae interiors. Similar processes may be taking place at other deep arcuate trenches or chasmata on Venus such as those in the Dali-Diana chasmata area of eastern Aphrodite Terra.     

Defective phagocytosis of isolated rod outer segments by RCS rat retinal pigment epithelium in culture

Retinal pigment epithelium cultured from normal rats phagocytizes large amounts of rod outer segment fragments isolated from normal rats and from RCS rats with inherited retinal degeneration. Cultured RCS rat pigment epithelium rarely ingests outer segment material, although the cells extend cellular processes around fragments of either type. Both normal and RCS pigment epithelium phagocytize polystyrene spheres. This demonstrates that RCS rat pigment epithelial cells contain a defect in the mechanism for phagocytizing outer segments.     

重金属铅镉对濒危植物中华水韭(Isoetes sinensis)DNA甲基化的影响

为研究古老植物对重金属胁迫的分子水平的响应,探究重金属对濒危植物DNA甲基化影响的特点,选择两种重金属Pb和Cd对濒危植物中华水韭进行胁迫处理,每种重金属设置3个处理浓度,胁迫处理至第28 d选取叶片,采用MSAP(甲基化敏感扩增多态性)技术测定DNA甲基化程度。试验结果表明:重金属铅和镉均能够对中华水韭DNA甲基化产生影响,甲基化总体水平基本一致(对照、Pb处理和Cd处理分别为46.96%、48.23%和48.1%),但全甲基化水平(Pb处理是28.34%,Cd处理是20.25%)均低于对照(33.91%),而半甲基化水平(Pb处理是19.89%,Cd处理是27.85%)均高于对照(13.04%)。甲基化增强的变化,以无甲基化或内外侧胞嘧啶半甲基化向内外侧胞嘧啶全甲基化变化的模式为主。去甲基化的变化,以内外侧胞嘧啶全甲基化向无甲基化或内侧胞嘧啶半甲基化或全甲基化变化的模式为主。铅和镉胁迫在导致中华水韭DNA甲基化增强所占比率方面几乎相等(39.04%和39.71%),而在去甲基化所占比率方面镉(46.86%)高于铅(33.92%)。     

套袋对‘红富士’苹果品质和Ca、Mg、K营养的影响

分别于盛花后25、35、45、55d对‘红富士’苹果进行套袋(果袋为内层红色袋、外层外灰内黑双层纸袋)处理,结果表明,早期套袋有提高果实单果重的趋势,降低果实可溶性固形物含量,对硬度和可滴定酸影响不大。果实成熟时,不同时期套袋对果肉Ca、K含量没有显著差异,但早期套袋增加果肉Mg含量,降低Ca/Mg比值。同时,在盛花后35d进行3种果袋(内层白、外层外灰内灰双层纸袋;内层黑、外层外灰内黑双层纸袋;内层红、外袋外灰内黑双层纸袋)处理表明,与对照(不套袋)相比,套袋使果实单果重增加,可溶性固形物含量降低,Ca含量、Ca/K影响不显著;而内袋红、外袋内黑外灰双层纸袋处理的果实Mg含量显著高于对照,内袋黑、外袋内黑外灰双层纸袋的果实K含量显著低于对照,并且上述两种果袋处理的果实Ca/Mg比值显著低于对照,其余果袋对品质和Ca,Mg,K均无明显的影响。     

西藏马颖蜡蝉属二新种(同翅目:颍蜡蝉科)

本文记述了分布于西藏的马颖蜡蝉属(同翅目:颖蜡蝉科)=新种,所有的模式标本保存在西北农业大学昆虫标本室。1.亚东马颖蜡蝉,新种。该新种与分布于四川的M.cerrina Fennah相近似,但体型大而色淡。前翅的前缘和外缘具有不规则的褐色大斑。雄性外生殖器特征与M.cerrina Fennah完全不同。2.吉隆马颖蜡蝉,新种。该新种与亚东马颖蜡蝉相近似,但额、前胸背板和中胸背板具有许多淡褐色小圆斑。前翅密布许多不规则的深褐色大斑。     

Prehistoric rock avalanches in the olympic mountains, washington

Rock avalanches blocked streams in the Olympic Mountains southwest of Puget Sound during the past few thousand years. Limiting radiocarbon ages indicated that three or four of six avalanches occurred from 1000 to 1300 years ago or shortly thereafter. Most of the dates were from the outer preserved rings of trees drowned behind avalanche dams. These three or four avalanches may be coeval not only with one another but also with abrupt tectonic deformation in western Washington. No rock avalanches in the Olympic Mountains are known to have resulted from storms or earthquakes during the past century. The avalanches strengthen the case that a large prehistoric earthquake occurred in the Puget Sound region.     

重庆市远郊种植业生产结构模型

本文在深入调查和掌握大量数据的基础上,建立了反映重庆市远郊14区县种植业生产结构的多目标线性规划模型,应用电算模拟技术分析了不同种植业结构模式下的生产资源利用方式及预期经济效果。经系统优化,提供了目前进行种植业结构调整的12个备挥方案。     

Time-resolved dynamics in N2O4 probed using high harmonic generation

The attosecond time-scale electron-recollision process that underlies high harmonic generation has uncovered extremely rapid electronic dynamics in atoms and diatomics. We showed that high harmonic generation can reveal coupled electronic and nuclear dynamics in polyatomic molecules. By exciting large amplitude vibrations in dinitrogen tetraoxide, we showed that tunnel ionization accesses the ground state of the ion at the outer turning point of the vibration but populates the first excited state at the inner turning point. This state-switching mechanism is manifested as bursts of high harmonic light that is emitted mostly at the outer turning point. Theoretical calculations attribute the large modulation to suppressed emission from the first excited state of the ion. More broadly, these results show that high harmonic generation and strong-field ionization in polyatomic molecules undergoing bonding or configurational changes involve the participation of multiple molecular orbitals.     

New dust belts of Uranus: one ring, two ring, red ring, blue ring

We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings.     

Migrations and growth of deep-sea lobsters, Homarus americanus

In distinct contrast to the restricted movements of coastal stocks of lobsters (Homarus americanus), those inhabiting the outer continental shelf undertake extensive seasonal migrations. Of 5710 tagged lobsters released on the outer continental shelf off New England from April 1968 to June 1969, 400 had been recaptured by April 1970. The distribution of the recoveries demonstrated shoalward migration in spring and summer and a return to the edge of the shelf in fall and winter. Deep-sea lobsters have a faster rate of growth than coastal lobsters; growth increments at molting and the frequency of molting are greater.     

雌性三角帆蚌外鳃组织形态周年变化及低氧胁迫对外鳃组织形态和酶活性影响

雌性三角帆蚌的外鳃不仅是呼吸器官,而且在繁育时期行使胚胎发育的育儿囊功能,繁育期鳃腔充满早期胚胎,呼吸效率降低。通过石蜡切片观察雌性三角帆蚌外鳃组织形态周年变化,并探究低氧环境对雌性三角帆蚌外鳃组织形态及酶活性的影响。结果表明,雌性三角帆蚌外鳃鳃瓣1月份最薄,至5月份增至最厚,较1月份显著增厚173.86%,随后鳃瓣逐渐变薄,其鳃小腔宽度随鳃瓣厚度增厚也显著增大,至6月增至最宽较1月份显著增宽171.22%,随后鳃小腔逐渐变窄;且3~6月在雌性三角帆蚌外鳃发育为育儿囊,其中发现大量早期胚胎。在低氧环境下,乳酸脱氢酶（LDH）活性在1~5天逐渐升高,第5天达到最大值,较对照组显著提升131.1%,5~9天缓慢下降;超氧化物歧化酶（SOD）活性在1~7天逐渐下降,在第7天达到最小值,较对照组显著降低40.53%,7~9天缓慢上升;过氧化氢酶（CAT）活性在1~7天逐渐上升,7~9天无明显变化,第7天活性最高,较对照组显著提升91.34%,琥珀酸脱氢酶（SDH）活性在1~9天呈下降趋势,最低值出现在第9天,较最对照组显著降低68.9%;低氧胁迫5天后,外鳃侧纤毛较对照组增宽了79.58%,外鳃小水管较对照组增宽了248.73%。本研究分别为怀卵期雌性三角帆蚌外鳃组织结构变化和低溶氧对雌性三角帆蚌外鳃组织结构和酶活性的影响提供了基础资料,为提升三角帆蚌繁育技术提供了理论依据。     

浅谈外墙保温材料技术

在建筑中,外围护结构的热损耗较大,外围护结构中墙体又占了很大份额。所以建筑墙 体改革与墙体节能技术的发展是建筑节能技术的一个最重要的环节,发展外墙保温技术及节能 材料则是建筑节能的主要实现方式。     

羊鲍精巢显微结构的研究

[目的]为羊鲍的人工繁殖提供理论基础。[方法]应用光镜技术研究羊鲍精巢的显微结构。[结果]羊鲍精巢由外膜及其内的大量生殖小管组成;外膜将生殖腺和肝胰腺分开,其组织结构由外至内依次为单层立方上皮、平滑肌纤维和结缔组织;生殖小管在生殖腺内部纵横交错,大量分枝,将生殖腺分隔成许多小腔,生殖小管内生殖细胞发育呈现区域化特征,成熟度越高的生殖细胞越靠近生殖小管腔的中央,反之则靠近生殖小管壁分布。[结论]羊鲍精巢中生殖细胞的发生及其性腺发育与皱纹盘鲍相类似。     

Gravity field and internal structure of Mercury from MESSENGER

Radio tracking of the MESSENGER spacecraft has provided a model of Mercury's gravity field. In the northern hemisphere, several large gravity anomalies, including candidate mass concentrations (mascons), exceed 100 milli-Galileos (mgal). Mercury's northern hemisphere crust is thicker at low latitudes and thinner in the polar region and shows evidence for thinning beneath some impact basins. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR(2) = 0.353 ± 0.017, where M and R are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of C(m)/C = 0.452 ± 0.035. A model for Mercury's radial density distribution consistent with these results includes a solid silicate crust and mantle overlying a solid iron-sulfide layer and an iron-rich liquid outer core and perhaps a solid inner core.     

Convergence of the secretory pathways for cholera toxin and the filamentous phage, CTXphi

Virulence of Vibrio cholerae depends on secretion of cholera toxin (CT), which is encoded within the genome of a filamentous phage, CTXphi. Release of CT is mediated by the extracellular protein secretion (eps) type II secretion system. Here, the outer membrane component of this system, EpsD, was shown to be required for secretion of the phage as well. Thus, EpsD plays a role both in pathogenicity and in horizontal transfer of a key virulence gene. Genomic analysis suggests that additional filamentous phages also exploit chromosome-encoded outer membrane channels.     

Observations of energetic ions from comet giacobini-zinner

During the encounter with comet Giacobini-Zinner, the energetic particle anisotropy spectrometer on the International Cometary Explorer spacecraft observed large fluxes of energetic ions, believed to result principally from ionization of the cometary atmosphere followed by pickup and acceleration by the ambient flow of the solar wind. These heavy cometary ions were observed from approximately 1 day before closest approach to about 2(1/2) days afterward. Three regimes of differing ion characteristics have been identified. An outer region with a scale of approximately 10(6) kilometers contains variable fluxes of antisolar-streaming pick-up ions in the undisturbed solar wind. In the middle region, of approximately 10(5) kilometers, fluxes have less large-scale variability and broader angular and energy distributions. This region is separated from the outer zone by a sharp transition. The inner region has a scale of approximately 10(4) kilometers and is characterized by reduced fluxes and complex angular distributions.     

狗牙花花瓣、花冠筒和花萼中气孔的分布特点及动态变化

对狗牙花的花瓣表皮、花冠筒和花萼的气孔分布情况及花发育过程中气孔密度和气孔指数的动态变化进行了研究.结果发现:狗牙花花瓣的上表皮没有气孔存在,花瓣的下表皮有气孔存在.外层花瓣下表皮的气孔指数和气孔密度均极显著的大于内层花瓣;在花萼外表皮和花冠筒外表皮有气孔存在.从第1～4阶段,花瓣下表皮和花冠筒外表皮的表皮细胞密度逐渐变小,花萼外表皮的表皮细胞密度逐渐增大;花瓣下表皮和花萼外表皮的气孔密度和气孔指数在第1阶段变小,从第2阶段开始又逐渐增大;花冠筒外表皮的气孔指数和气孔密度呈变小趋势.第1、第2和第3阶段气孔指数和气孔密度在花萼外表皮最大、花瓣下表皮最小,第4阶段花冠筒外表皮的气孔指数和气孔密度小于花瓣下表皮外.     

圆齿野鸦椿种子内含物的提取·分离以及生物测定

[目的]研究圆齿野鸦椿种子内含物的成分及作用。[方法]以圆齿野鸦椿种子为材料,对其内含物进行提取、分离,并进行白菜籽萌发试验。[结果]不同时期采集的圆齿野鸦椿种子的内、外种皮及胚含有不同种类及浓度的萌发抑制剂。[结论]圆齿野鸦椿种子外种皮、内种皮及胚中抑制萌发物质的存在是引起其休眠的原因之一。     

长株潭一体化条件下远郊型农村产业发展初探——以炎陵县龙凤村为例

在长株潭一体化及国家"两型社会"改革试验区的新形势下,如何充分利用政策优势、地域优势、资源优势来加快长株潭远郊型农村地区又好又快发展是一个值得探讨的新课题。以株洲市炎陵县龙凤村为远郊型农村典型试验区,在对试验区自然地理条件、区位优势以及农村产业发展现状等进行深入调查的基础上,结合国内外远郊型农村产业发展的先进经验,对试验区农村产业发展方面存在的问题进行了深入分析,提出了试验区主要农业产业发展模式,并对其农村产业未来的发展进行了规划。     

墨兰组织培养中原球茎的形态解剖研究

通过对墨兰（Ｃｙｍｉｄｉｕｍ ｓｉｎｅｎｓｅ）组织培养中原球茎外部形态、内部结构的观察研究,发现墨兰茎尖组织培养中产生的原球茎和丛生型原球茎虽外形差别较大,但内部结构都具有根的典型特征。牙的分生组织可以在原球茎表层、丛生型原球茎或其顶端发生。芽的顶端分生组织与随后产生的根的顶端分生组织共同构成胚状结构,其形态与种子胚相似。由于墨兰组培中先后产生的原球茎和丛生型原球茎其内部结构都属典型的根结构,故称