143 resultados para Leaves.


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Feeding and vocal behaviours of wild black gibbons (Hylobates concolor) were observed from 1987 to 1989 in south-western Yunnan, notably H. concolor jingdongensis at Mt. Wuliang (24-degrees 18-42'N, 100-degrees 30-50'E) in the early spring of 1989. 12 plant species were observed to have been eaten by the gibbons; these included tree species, lianas and epiphytes. Approximately 21 % of feeding time was devoted to eating fruits, 61 % to leaf buds and shoots, 7 % to flowers and 11 % to leaves. The gibbons preferred fruits to leaves even though they commonly ate leaves. In this study, the morning songs (duet and solo), reponsive (territorial) songs, alarm calls and communication calls were recorded. The gibbons sang their morning songs mainly in the early morning, with a single bout lasting more than 10 min on average. The singing of a group would trigger other groups, and all groups in an area tended to sing sequentially. The morning duet song bout was dominated by an adult male. The male emitted booms, aa notes, early multimodulated figures, intermediate multimodulated figures and codas, the latter occurring only in duets following the female's great call. The female uttered great calls and abortive great calls. The subadults or juveniles also took part in the morning songs. Lone males were heard to utter solos which lasted longer than the duets of the pairs.

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Provisioning along pedestrian trails by tourists much increased the nutrient quality and patchiness of food (NqPF)for Tibetan macaques (Macaca thibetana) at Mt Emei in spring and summer. In the habitat at a temperate-subtropical transition zone, the mncaque's NqPF could be ordered in a decreasing rank from spring summer to autumn to winter With the aid of a radio-tracking system, I collected ranging data on a multigroup community in three 70-day periods representing the different seasons in 1991-92, Rank-order correlation on the data show that with the decline of NqPF; the groups tended to increase days away from the trail, their effective range size (ERS) their exclusive area (EA) and the number of days spent in the EA, and reduced their group/community density and the ratio of the overlapped range to the seasonal range (ROR). In icy/snowy winter; the macaques searched for mature leaves slowly and carefully in the largest seasonal range with a considerable portion that was nor used in other seasons. Of the responses, the ROR decreased with the reduction in group/community density; and the ERS was the function of both group size (+) and intergroup rank (-) when favorite food was highly clumped. All above responses were clearly bound to maximize foraging effectiveness and minimize energy expenditure, and their integration in term of changes in time and space leads to better understanding macaque ecological adaptability. Based on this study and previous work on behavioral and physiological factors, I suggest a unifying theory of intergroup interactions. Ir! addition, as the rate of behavioral interactions,was also related to the group density, I Waser's (1976) gas model probably applies to behavioral, as well as spatial, data on intergroup interactions.

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Host feeding selection by the female pea leafminer, Liriomyza huidobrensis, on 47 species of plants was studied. The leaves were sectioned by microtome, and 15 characteristics of the leaf tissue structure were measured under a microscope. Correlation analysis between host feeding selection and leaf tissue structure indicated that the preference of host feeding selection was positively correlated with the percentage of moisture content of leaves and negatively with thickness of the epidermis wall, and densities of the palisade and spongy tissues of leaves. Leaf tissue structure was influential in feeding and probing behavior of female L. huidobrensis. So, thickness of epidermis wall, densities of the palisade and spongy tissues can act as a physical barrier to female oviposition. Furthermore, higher densities of palisade and spongy tissues can be considered a resistant trait which affects mining of leaf miner larvae as well. As a result, plants with lower leaf moisture content may not be suitable for the development of L. huidobrensis.

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In order to examine how carbon and nitrogen status of a macrophyte may affect its total phenolics (TP) production, the contents of free amino acids (FAA), soluble carbohydrate (SC) and TP were examined in leaves of seven submersed, four floating-leaved, and four emergent macrophytes. The floating-leaved and emergent macrophytes had much higher contents of SC and TP than the submersed macrophytes. The contents of FAA were not significantly different among the submersed, floating-leaved, and emergent macrophytes. Correlations among the contents of FAA, SC, and TP indicated that the production of TP was more dependent on the SC content than on the FAA content.

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Photosynthetic responses to irradiance and temperature of "leaves" and receptacles were compared in February ( vegetative stage) and May ( reproductive stage) in the seaweed, Hizikia fusiforme ( Harvey) Okamura (Sargassaceae, Phaeophyta) from Nanao Island, Shantou, China. Irradiance-saturated photosynthesis (P-max) was significantly higher in receptacles than in "leaves" on a fresh weight basis, and that of "leaves" was greater in May than in February at ambient seawater temperatures. The optimum temperature for P-max was 30 degrees C for both "leaves" and receptacles, being 5 - 10 degrees C higher than the ambient seawater temperature. The apparent photosynthetic efficiencies were greater in receptacles than in "leaves" within the tested temperature range of 10 - 40 degrees C. The irradiance for saturating photosynthesis for both "leaves" and receptacles was temperature-dependent, with the highest values ( about 200 mu mol photons m(-2) s(-1)) at 30 degrees C.

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Goal, Scope and Background. In some cases, soil, water and food are heavily polluted by heavy metals in China. To use plants to remediate heavy metal pollution would be an effective technique in pollution control. The accumulation of heavy metals in plants and the role of plants in removing pollutants should be understood in order to implement phytoremediation, which makes use of plants to extract, transfer and stabilize heavy metals from soil and water. Methods. The information has been compiled from Chinese publications stemming mostly from the last decade, to show the research results on heavy metals in plants and the role of plants in controlling heavy metal pollution, and to provide a general outlook of phytoremediation in China. Related references from scientific journals and university journals are searched and summarized in sections concerning the accumulation of heavy metals in plants, plants for heavy metal purification and phytoremediation techniques. Results and Discussion. Plants can take up heavy metals by their roots, or even via their stems and leaves, and accumulate them in their organs. Plants take up elements selectively. Accumulation and distribution of heavy metals in the plant depends on the plant species, element species, chemical and bioavailiability, redox, pH, cation exchange capacity, dissolved oxygen, temperature and secretion of roots. Plants are employed in the decontamination of heavy metals from polluted water and have demonstrated high performances in treating mineral tailing water and industrial effluents. The purification capacity of heavy metals by plants are affected by several factors, such as the concentration of the heavy metals, species of elements, plant species, exposure duration, temperature and pH. Conclusions. Phytoremediation, which makes use of vegetation to remove, detoxify, or stabilize persistent pollutants, is a green and environmentally-friendly tool for cleaning polluted soil and water. The advantage of high biomass productive and easy disposal makes plants most useful to remediate heavy metals on site. Recommendations and Outlook. Based on knowledge of the heavy metal accumulation in plants, it is possible to select those species of crops and pasturage herbs, which accumulate fewer heavy metals, for food cultivation and fodder for animals; and to select those hyperaccumulation species for extracting heavy metals from soil and water. Studies on the mechanisms and application of hyperaccumulation are necessary in China for developing phytoremediation.

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The effects of cadmium (Cd2+) on growth status, chlorophyll (Chl) content, photochemical efficiency, and photosynthetic intensity were studied on Canna indica Linn. Plant specimens that were produced from a constructed wetland and precultivated hydroponically in 20 L of 1/10 Hoagland solution under greenhouse conditions for I week were exposed to cadmium in concentrations of 0, 0.4, 0.8, 1.6 and 3.2 mg L- Cd2+, respectively. The results show that leaves were injured in the Cd2+ solution by the third day of exposure and the injury became more serious with an increase in the applied heavy metal. Under 3.2 mg L-1 Cd2+ treatment, growth retardation, the decrease of chlorophyll content from 0.70 to 0.43 mg g(-1) FW, and a decrease in Chl a/b ratio from 2.0 to 1.2 were observed. Chl a was more sensitive than Chl b to Cd2+ stress. The decrease was the same with photochemical efficiency. Photosynthetic intensity decreased by 13.3% from 1.5X10(4) mumol m(-2)s(-1) CO2 in control to 1.3x10(4) mumol m(2)s(-1) CO2 in the treatment of 3.2 mg L-1. Because Canna species are used in heavy metal phytoremediation, these results show that C. indica can tolerate 0.4 to 0.8 mg L-1 Cd2+. Therefore, it is a potential species for phytoremediation of cadmium with some limitations only at higher concentrations.

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Superoxide dismutase activity in water hyacinth leaves was not sensitive to small changes in environmental pH, but declined markedly with greater pH changes. KCN inhibited superoxide dismutase activity, suggesting that the enzyme was mainly composed of the Cu-Zn form. Low temperature (2-degrees-C) treatment caused a decline in superoxide dismutase activity. This effect became more pronounced as the treatment time was prolonged. Furthermore, the decline was much more significant than reductions of glucose-6-phosphate dehydrogenase activity or respiration under comparable conditions. With increasing physiological age, superoxide dismutase activity declined and was significantly lower in old than in young leaves. Therefore, superoxide dismutase activity might be employed as one of physiological parameters in studying leaf senescence.

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Atomic configurations and formation energies of native defects in an unsaturated GaN nanowire grown along the [001] direction and with (100) lateral facets are studied using large-scale ab initio calculation. Cation and anion vacancies, antisites, and interstitials in the neutral charge state are all considered. The configurations of these defects in the core region and outermost surface region of the nanowire are different. The atomic configurations of the defects in the core region are same as those in the bulk GaN, and the formation energy is large. The defects at the surface show different atomic configurations with low formation energy. Starting from a Ga vacancy at the edge of the side plane of the nanowire, a N-N split interstitial is formed after relaxation. As a N site is replaced by a Ga atom in the suboutermost layer, the Ga atom will be expelled out of the outermost layers and leaves a vacancy at the original N site. The Ga interstitial at the outmost surface will diffuse out by interstitialcy mechanism. For all the tested cases N-N split interstitials are easily formed with low formation energy in the nanowires, indicating N-2 molecular will appear in the GaN nanowire, which agrees well with experimental findings.

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We have studied the spontaneous emission of polarized excitons in the GaInP/AlGaInP vertical-cavity surface-emitting lasers from 50 K to room temperature. It is observed that the spontaneous emission peak enters and leaves the resonant regime. At the resonant regime, the emission intensities of the perpendicularly and horizontally polarized excitons are enhanced and their proportions are different from that in nonresonant regime. These experimental results are explained by the dressed exciton theory of the semiconductor microcavity device. Based on this theory, the intensity enhancement and the polarization dependence are understood as cooperative emission and the microcavity anisotropy. (C) 2000 American Institute of Physics. [S0021-8979(00)05315-9].

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This article introduced an effective design method of robot called remote-brain, which is made the brain and body separated. It leaves the brain in the mother environment, by which we mean the environment in which the brain's software is developed, and talks with its body by wireless links. It also presents a real robot TUT06-B based on this method which has human-machine interaction, vision systems, manipulator etc. Then it discussed the path planning method for the robot based on ant colony algorithm in details, especially the Ant-cycle model. And it also analyzed the parameter of the algorithm which can affect the convergence. Finally, it gives the program flow chat of this algorithm.

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The hydrogen production from the organic fraction of municipal solid waste (OFMSW) by anaerobic mixed culture fermentation was investigated using batch experiments at 37 degrees C. Seven varieties of typical individual components of OFMSW including rice, potato, lettuce, lean meat, oil, fat and banyan leaves were selected to estimate the hydrogen production potential. Experimental results showed that the boiling treated anaerobic sludge was effective mixed inoculum for fermentative hydrogen production from OFMSW. Mechanism of fermentative hydrogen production indicates that, among the OFMSW, carbohydrates is the most optimal substrate for fermentative hydrogen production compared with proteins, lipids and lignocelluloses. This conclusion was also substantiated by experimental results of this study. The hydrogen production potentials of rice, potato and lettuce were 134 mL/g-VS, 106 mL/g-VS, and 50 mL/g-VS respectively. The hydrogen percentages of the total gas produced from rice, potato and lettuce were 57-70%, 41-55% and 37-67%. 2008 International Association for Hydrogen Energy.

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We provide three-dimensional numerical simulations of conjugate heat transfer in conventional and the newly proposed interrupted microchannel heat sinks. The new microchannel heat sink consists of a set of separated zones adjoining shortened parallel microchannels and transverse microchambers. Multi-channel effect, physical property variations, and axial thermal conduction are considered. It is found that flow rate variations in different channels can be neglected, while heat received by different channels accounts for 2% deviations from the averaged value when the heat flux at the back surface of the silicon chip reaches 100 W/cm(2). The computed hydraulic and thermal boundary layers are redeveloping in each separated zone due to shortened flow length for the interrupted microchannel heat sink. The periodic thermal developing flow is responsible for the significant heat transfer enhancement. Two effects influence pressure drops across the newly proposed microchannel heat sink. The first one is the pressure recovery effect in the microchamber, while the second one is the head loss when liquid leaves the microchamber and enters the next zone. The first effect compensates or suppresses the second one, leading to similar or decreased pressure drop than that for the conventional microchannel heat sink, with the fluid Prandtl number larger than unity.

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利用不同pH值的酸碱溶液处理蚕豆或者离体蚕豆叶片,研究酸碱胁迫下蚕豆叶片保护酶活性的变化。结果表明,离体蚕豆叶片处理10 min和30 min的SOD活性相差不大,整株处理5 h的蚕豆叶片SOD活性远大于处理12 h的SOD活性;离体蚕豆叶片和整株蚕豆处理,较长时间处理下的CAT活性基本上高于短时间处理的CAT活性,短时间处理下(10 min、5 h)POD活性均显著低于对照值,较长时间处理(30 min、12h)下POD活性变化的规律性不强,且变化幅度较小。

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采用室内培养皿滤纸法进行种子发芽的方法,通过测定早酥梨叶片浸提液对几种蔬菜种子胚根生长的影响,研究了不同浓度浸提液对几种蔬菜的化感作用。为制定合理的间套作耕作制度,更好的安排果树生产布局提供科学依据。结果表明:早酥梨叶片浸提液对蔬菜胚根生长的影响总体上表现为低促、高抑,即低浓度的浸提液对蔬菜胚根的生长有促进作用,较高浓度的浸提液对蔬菜胚根的生长产生抑制作用,浓度越高,抑制作用越强。不同生长年限的早酥梨叶提取液对其间作套种蔬菜抑制作用的强弱顺序为生长第6年>第7年>12年>生长第22年>第4年。