检索结果-南通市图书馆

Increased Maleness at Flowering Stage and Femaleness at Fruiting Stage with Size in an Andromonoecious Perennial, Veratrum nigrum

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2008年第8期50卷 1024-1030页

作者： wan-jin Liao Da-Yong Zhang Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering & Institute of Ecology Beijing Normal University Beijing 100875 China

Theory predicts that cosexual plants should adjust their resource investment in male and female functions according to their size if female and male fitness are differentially affected by size. However, few empirical studies have been carried out at both the flowering and fruiting stages to adequately address size-dependent sex allocation in cosexual plants. In this paper, we investigated resource investment between female and male reproduction, and their size-dependence in a perennial andromonoecious herb, Veratrum nigrum L. We sampled 192 flowering plants, estimated their standardized phenotypic gender, and assessed the resource investment in male and female functions in terms of absolute dry biomass. At the flowering stage, male investment increased with plant size more rapidly than female investment, and the standardized phenotypic femaleness （ranging from 0.267 to 0.776） was negatively correlated with plant size. By contrast, female biased allocation was found at the fruiting stage, although both flower biomass and fruit biomass were positively correlated with plant size. We propose that increased maleness with plant size at the flowering stage may represent an adaptive strategy for andromonoecious plants, because male flowers promote both male and female fertility by increasing pollinator attraction without aggravating pollen discounting.

关键词： andromonoecy phenotypic gender size-dependent sex allocation Veratrum nigrum

Electrokinetic movement of multiple chlorobenzenes in contaminated soils in the presence of β-cyclodextrin

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2007年第8期19卷 968-976页

作者： YUAN Song-hu wan jin-zhong LU Xiao-hua School of Environmental Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China.

This study investigated the electrokinetic （EK） behavior of multiple chlorobenzenes, including 1,2,3,4-tetrachlorobenzene （TeCB）, 1,2,4,5-tetrachlorobenzene （i-TeCB）, and 1,2,3-trichlorobenzene （TCB） in contaminated clayed soils. The effect of β-cyclodextrin （β- CD） on the EK removal of the chlorobenzenes was studied. The largest removal was obtained when Na2CO3/NaHCO3 buffer was used as anodic purging solution without β-CD. The removal efficiencies were related to the aqueous solubilities of chlorobenzenes. With the same cumulative electroosmotic flow, greater solubility led to higher removal efficiency. The addition of β-CD inhibited the EK removal efficiency of all chlorobenzenes. The inhibition increased with the increase of β-CD concentration. With the same β-CD concentration, the inhibition increased with the rise of electric potential. It was found that the inclusion compounds between β-CD and chlorobenzenzes were less soluble than chlorobenzenes. The formation of the less soluble inclusion compounds reduced the aqueous solubility of chlorobenzenes and led to the partial immobilization of the chlorobenzenes that desorbed from soil. It was feasible to use the EK technology to remove chlorobenzenes in contaminated soils using water as the anodic flushing solution. The addition of β-CD was not recommended for the EK removal of chlorobenzenes.

关键词： chlorobenzenes electrokinetic soil remediation β-cyclodextrin (β-CD)

Numerical Investigation on Wet Steam Non-equilibrium Condensation Flow in Turbine Cascade

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2012年第6期21卷 525-532页

作者： JU Feng-ming YAN Pei-gang HAN wan-jin School of Energy Science & Engineering Harbin Institute of Technology Harbin 150001 China

Based on the two-phase wet steam flow with spontaneous condensation, experimental verification and flow analysis on nozzle and 2D cascade are carried out. The 3D Reynolds-Averaged gas-liquid two-phase flow control equation solver is explored with k-e-kp turbulence model. Furthermore, 3D flow numerical simulation on the last stage stator of the steam turbine is carried out. The results show that a sudden pressure rise on blade suction surface is mainly caused by the droplet growth in condensation flow. The more backward the condensation position is in cascade passage, the less the sudden pressure rise from condensation is, and the larger the nucleation rate is, the maximum under-cooling and the number of droplets per unit volume are. Interaction of condensation wave and shock wave has imposed greater influence on the parameters of the blade cascade outlet.

关键词： turbine cascade wet steam non-equilibrium condensation two-phase flow

A Novel Route to Synthesize Nano-crystalline Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O(3-δ) Perovskite Oxide at High Temperature

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2006年第10期17卷 1353-1356页

作者： Wei ZHOU Zong Ping SHAO wan Qin jin Key Laboratory of Materials-Oriented Chemical Engineering of Ministry of Education of China College of Chemistry and Chemical Engineering Nanjing University of Technology Nanjing 210009

It is normally difficult to prepare nano-sized Ba0.5Sr0.5Co0.8Fe0.2O3-δ（BSCF） oxide at high temperature due to its high surface activity. The complexing process, which has successfully applied in the synthesis of nano Sm0.15Ce0.85I1.925 with crystallite size down to 5 nml, just resulted in a coarse BSCF with crystaUite size of 41.9 nm at 900℃. We applied a novel process by simply modifying the solid precursor from the complexing process with concentrated nitric acid treatment. The obtained BSCF powder had a crystaUite size of -25 nm even calcined at 1000℃. The small crystaUite size is extremely promising to enhance the electrochemical performance of cathode for solid oxide fuel cell dramatically.

关键词： Nano-crystallite perovskite solid oxide fuel cells.

Pollen and Resource Limitation in Veratrum nigrum L. （Liliaceae）, an Andromonoecious Herb

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2006年第12期48卷 1401-1408页

作者： wan-jin Liao Qing-Fa Song Da-Yong Zhang Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering and Institute of Ecology Beijing Normal University Beijing 100875 China

Pollen limitation and resource limitation were invoked to account for the pattern that flowering plants produce more flowers and ovules than fruits and seeds. This study aimed to determine their relative importance in Veratrum nigrum, a self-compatible, perennial, andromonoecious herb. In order to determine whether female production was limited by pollen grains on stigmas or by available resources, we performed supplemental hand pollination in three populations, male-flower-bud removal in three other populations, and emasculation of hermaphroditic flowers in still another population, resulting in a total of seven populations experimentally manipulated. Across the three populations, supplemental hand pollination did not significantly increase fruit set, seed number per fruit, and total seed production per individual, nor did emasculation of hermaphroditic flowers. Taken together, our results suggest that pollen grains deposited on stigmas were abundant enough to fertilize all the ovules. Male-flower-bud removal significantly increased the mean size of hermaphroditic flowers in all three populations. Female reproductive success was increased in one population, but not in the other two populations possibly due to heavy flower/seed predation. We concluded that the female reproductive success of V. nigrum was not limited by pollen grains but by available resources, which is consistent with Bateman＇s principle. Furthermore, the female reproduction increase of male-flower-bud removal individuals might suggest a trade-off between male and female sexual functions.

关键词： andromonoecy pollen limitation resource limitation trade-off Veratrum nigrum

A 2.5D finite element approach for predicting ground vibrations generated by vertical track irregularities

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第12期12卷 885-894页

作者： Xue-cheng BIAN Chang CHAO wan-feng jin Yun-min CHEN MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Department of Civil Engineering Zhejiang University Hangzhou 310058 China

Dynamic responses of track structure and wave propagation in nearby ground vibration become significant when train operates on high speeds. A train-track-ground dynamic interaction analysis model based on the 2.5D finite element method is developed for the prediction of ground vibrations due to vertical track irregularities. The one-quarter car mode,1 is used to represent the train as lumped masses connected by springs. The embankment and the underlying ground are modeled by the 2.5D finite element approach to improve the computation efficiency. The Fourier transform is applied in the direction of train＇s movement to express the wave motion with a wave-number. The one-quarter car model is coupled into the global stiffness matrix describing the track-ground dynamic system with the displacement compatibility condition at the wheel-rail interface, including the irregularities on the track surface. Dynamic responses of the track and ground due to train＇s moving loads are obtained in the wave-number domain by solving the governing equation, using a conventional finite element procedure. The amplitude and wavelength are identified as two major parameters describing track irregularities. The irregularity amplitude has a direct impact on the vertical response for low-speed trains, both for short wavelength and long wavelength irregularities. Track irregularity with shorter wavelength can generate stronger track vibration both for low-speed and high-speed cases. For low-speed case, vibrations induced by track irregularities dominate far field responses. For high-speed case, the wavelength of track irregularities has very little effect on ground vibration at distances far from track center, and train＇s wheel axle weights becomes dominant.

关键词： High-speed railway 2.5D finite element method One-quarter car model Ground vibration Track irregularities

Dysdera dushengi sp. nov., the easternmost species of the spider family Dysderidae(Arachnida: Araneae)

在线全文

学校读者我要写书评

暂无评论

Zoological Systematics 2020年第2期45卷 97-103页

作者： Yejie Lin wan-jin Chang Shuqiang Li Institute of Zoology Chinese Academy of SciencesBeijing 100101China

Dysderidae ***,1837 is reported from China for the first time.A new species of the genus Dysdera Latreille,1804,*** *** Xinjiang Uygur Autonomous Region,is described based on both *** new species is closely related to... 详细信息

关键词： Xinjiang China taxonomy new record morphology

Two Novel Myrinsol Diterpenes from Euphorbia prolifera

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2002年第8期13卷 744-747页

作者： wan jin ZHANG Dao Feng CHEN Ai Jun HOU Department of Pharmacognosy School of PharmacyFudan UniversityShanghai 200032

Two novel diterpenes, Euphorprolitherin A (1) and Euphorprolitherin B (2), were isolated from the roots of Euphorbia prolifera. Their structures were elucidated on the basis of spectroscopic methods.

关键词： Euphorbia prolifera Euphorbiaceae myrinsol diterpenes euphorprolitherin A euphorprolitherin B.

Ground-borne vibrations due to dynamic loadings from moving trains in subway tunnels

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第11期13卷 870-876页

作者： Xue-cheng BIAN wan-feng jin Hong-guang JIANG Department of Civil Engineering MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310058 China

In this study,ground vibrations due to dynamic loadings from trains moving in subway tunnels were investigated using a 2.5D finite element model of an underground tunnel and surrounding soil *** our model,wave propagation in the infinitely extended ground is dealt with using a simple,yet efficient gradually damped artificial *** on the assumption of invariant geometry and material distribution in the tunnel's direction,the Fourier transform of the spatial dimension in this direction is applied to represent the waves in terms of the *** element discretization is employed in the cross-section perpendicular to the tunnel direction and the governing equations are solved for every discrete *** 3D ground responses are calculated from the wave-number expansion by employing the inverse Fourier *** accuracy of the proposed analysis method is verified by a semi-analytical solution of a rectangular load moving inside a soil stratum.A case study of subway train induced ground vibration is presented and the dependency of wave attenuation at the ground surface on the vibration frequency of the moving load is discussed.

关键词： Subway tunnel Moving train loadings Ground-borne vibration 2.5D finite element Gradually damped artificial boundary