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991.
A new sesquiterpene lactone, 7alpha,10alpha-epoxy-1alpha(H),5alpha(H)-guaia-3,11(13)-dien-8alpha,12-olide, was isolated from the leaves of Hedyosmum arborescens. The structure of this unusual 7,10-epoxy-guaianolide was determined by spectroscopic methods, particularly one- and two-dimensional 1H and 13C NMR. 相似文献
992.
New Forests - Monterrey Forestal Ltda conducted a study to determine the effects of different stocking on productivity of Gmelina arborea (gmelina) to age 6 years in Zambrano, Bolívar,... 相似文献
993.
Effects of drought on water relations, whole-shoot gas-exchange characteristics, and pigment and zeatin concentrations were investigated in the Mediterranean shrubs rosemary (Rosmarinus officinalis L.) and lavender (Lavandula stoechas L.). Two-year-old, greenhouse-grown plants were placed in a whole-shoot gas-exchange measurement system and subjected to 10 days of drought, resulting in severe water stress, and then re-watered for 5 days in order to study their recovery. Water stress resulted in a significant decline in maximum whole-shoot net CO2 assimilation rates (An) for both species that was associated with reductions in leaf area and stomatal conductance. Because shoot dark respiration rate (Rd) was less sensitive to water stress than An, shoot Rd/An ratio increased from about 15 to 95% during water stress. No major changes in chlorophyll and carotenoid concentrations of rosemary leaves were observed during the experiments, but chlorophyll and carotenoid concentrations fell significantly in water-stressed lavender leaves. Zeatin concentrations were higher in rosemary leaves than in lavender leaves during water stress. After re-watering, whole-shoot An and Rd rapidly recovered to their pre-drought rates. 相似文献
994.
Chang-Hua Fang Bruno Clair Joseph Gril Tancrède Alméras 《Wood Science and Technology》2007,41(8):659-671
Transverse drying shrinkage was measured at microscopic and mesoscopic levels in poplar wood characterised by an increasing
growth strain (GS), from normal to tension wood. Results show that: (a) the drying shrinkage, measured as a relative thickness
decrease, was significantly higher for G-layer (GL) than for the other layers (OL), GL shrinkage was not significantly correlated
with GS, and OL shrinkage was negatively correlated with GS. (b) In gelatinous fibre (G-fibre), lumen size increased during
drying and this increase was positively related with GS, but in normal wood fibre, lumen size decreased during drying. These
findings suggest that GL shrank outwards (i.e., its internal perimeter increases), so that its shrinkage weakly affected the
total cell shrinkage and the mesoscopic shrinkage was controlled by the OL shrinkage which shrank inwards (i.e., its external
perimeter decreases). (c) Measurements done on 7 × 7 mm2 thin sections evidenced a negative correlation between transverse
shrinkage and GS, significant in T direction but weak in R direction. These observations at both levels allow to discuss the
contribution of GL to the mesoscopic shrinkage of tension wood. 相似文献
995.
Conjugation of δ-endotoxin from Bacillus thuringiensis with abamectin, a toxin of Streptomyces avermitilis, was carried out to form a new type of biocide, GCSC-BtA based on “Germany-China Scientific Cooperation” research, for the control of agricultural insect pests. The strategy for biochemical linkage was designed by conjugating an amino group in B.t. protoxin with a carboxyl group in carboxylated abamectin under the treatment of conjugator EDC [1-Ethyl-3-(3-dimethylaminopropyl carbodiimide Hydrochloride)]. The formation of B.t. protoxin was processed by solubilizing B.t. crystal in 25?mM dithiothreitol (DTT) at 37?°C for 2?h. The carboxylated abamectin was formed by carboxylating the NaH-activated abamectin with 10?mg/ml butyric anhydride at 111?°C in a water-circumfluent condensation device for 2?h. The conjugating reaction, consisting of 5?mg/ml B.t. protoxin, 10?mg/ml carboxylated abamectin and 19.17?mg/ml EDC, was successfully conducted at room temperature for 24?h. Significant differences were found between pure abamectin, carboxylated abamectin and the conjugated BtA by means of UV-photo absorptions recorded at wavelengths 354, 438, 518, 600?nm (P?<?0.01). LT50 of the conjugated GCSC-BtA to the 3rd instar larvae of Plutella xylostella (L.) (Lep., Plutellidae) was 35.27 μg a.i./ml, about 62?% and 76?% of that caused by the B.t. protoxin and the caxboxylated abamectin, respectively. The conjugated GCSC-BtA caused 87.14?% mortalities in larvae of P. xylostella, 93.75?% in adult Myzus persicae (Sulzer) (Hom., Aphididae) and 89.33?% in adult Phyllotreta vittata Fabricius (Col., Chrysomelidae) as compared to 48.33?% by the B.t. crystal only in P. xylostella. The symptoms caused by conjugated GCSC-BtA in the 3rd instar of P. xylostella were black color in the head part and white-yellow in the abdomen of dead larvae, which differed from the black color or the white-yellow all along the body caused by either the B.t. crystal or the abamectin, respectively. It was concluded that the conjugated GCSC-BtA biocide had a broader host spectrum and a faster killing speed than either the B.t. crystal or abamectin alone for the control of agricultural pests. 相似文献
996.
Camacho-Hernández IL Chávez-Velázquez JA Uribe-Beltrán MJ Ríos-Morgan A Delgado-Vargas F 《Fitoterapia》2002,73(5):411-413
The methanol extract of the fruit pulp of Bromelia pinguin was evaluated for its antifungal activity. The extract showed a significant activity against some Trichophyton strains, although Candida strains were generally insensitive. 相似文献
997.
Black locust (Robinia pseudoacacia L.) is one of the most important stand-forming tree species in Hungary and its importance is increasing in many countries.
Black locust plants are commonly produced by two methods, by seed and by root cuttings. Tissue culture propagation can be
considered as a relatively new method. Growing trees from seed is a relatively simple method for reliably producing seedlings
on a large scale under a variety of circumstances. Mechanization of the method is easy and the production cost is relatively
low. Propagation from root cuttings and tissue culture are valuable for reproduction of superior individuals or varieties.
By applying these methods, superior traits of the selected trees can be preserved in the clones. Recent experiments demonstrated
that micropropagated trees could be successfully transplanted into soil, hardened and grown in the field.
Biography: Karoly Redei (1952), male, doctor, deputy director general of Hungarian Forest Research Institute H-1023 Budapest, Frankel
Leó Str. 42 44, HUNGARY.
Responsible editor: Chal Ruihai 相似文献
998.
From the isopropyl acetate fraction obtained by partition of the leaves ethanolic extract of Alchornea glandulosa, six phenolic compounds were isolated and identified. General lethality of the extract, fractions and compounds were assayed with Brine Shrimp Test (BST) and with Antifeedant Activity Bioassay (AAB) against neonate larvae of Spodoptera frugiperda. Aqueous fraction and ethyl gallate, one of the major constituents of the polar fraction, have shown the highest toxicity in BST. Ethanolic extract, isopropyl acetate fraction and gallic acid reduced significantly larval growth of S. frugiperda neonates. 相似文献
999.
V. P. Sharma T. K. Wan G. H. S. Hooper B. Würzer Klara B. Balász J. Bodor 《Journal of pest science》1969,42(1):14-15
Ohne Zusammenfassung 相似文献
1000.
胡杨幼苗黑星病初步研究 总被引:1,自引:0,他引:1
对发生于新疆吉木萨尔是胡杨上的黑星病进行了调查研究,经鉴定该病是由山杨黑星孢菌[(Fusicladium tremulas (Fr.)Aderh]引起。病害的发病程度与品种有关,不同胡杨品种的感病程度依次为:胡杂1号>胡杂3号>胡杂4号>胡杂2号>胡杂5号;苗高、地径及叶甲数量与感病指数之间无显著相关性。 相似文献