共查询到20条相似文献，搜索用时 500 毫秒
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萃取赖百当及其化学成分研究 总被引：2，自引：1，他引：1
用超临界CO2萃取技术，在压力28MPa、温度40℃、反应时间3h及CO2流量30L／h的条件下，对岩蔷薇(Cistus labdaniferus L．)的枝叶进行萃取，得到赖百当(Labdanum)萃取物。并以苯为溶剂，采用索氏抽提法制备赖百当浸膏；用水蒸气蒸馏法提取赖百当精油。对不同提取工艺得到的赖百当产品的得率及质量进行了分析比较，超临界CO2萃取法产品得率最高，为6．6％(苯萃取法为4．8％，水蒸气蒸馏法为0．8％)，且品质优于苯萃取法产品。用GC-MS分别对超临界CO2萃取物和水蒸气蒸馏精油的化学成分及相对含量进行了测定，共鉴定出31种化合物，其中超临界CO2萃取物中31种，水蒸气蒸馏精油中26种。 相似文献
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从压榨法、浸提法、水蒸气蒸馏法、有机溶剂萃取法、超声波法、微波萃取法、超临界二氧化碳萃取技术等方面介绍了柑橘有效化学成分的提取方法,比较了各种方法的优缺点及应用现状。 相似文献
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超临界CO2萃取法和水蒸气蒸馏法提取香榧外种皮化学成分研究 总被引：1，自引：0，他引：1
分别采用超临界CO2萃取法和水蒸气蒸馏法提取香榧外种皮提取物,并采用GC-MS分析手段对提取物的化学组成进行了定性和定量测定.从超临界CO2萃取的香榧外种皮提取物中鉴定出40个组分,相对含量较多的是香榧酯(14.90%)和7,15-海松二烯-3-酮(14.45%);由水蒸气蒸馏法得到的提取物中,相对含量较多的是柠檬烯(32.90%),β-蒎烯(13.48%);依据官能团来划分,超临界CO2萃取出的香榧外种皮提取物中,化学成分比较全面,含量均衡;而水蒸气蒸馏法得到的产物以沸点较低的单萜类烯烃居多. 相似文献
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为了探明微波法提取兴安百里香精油最佳提取条件及其主要组分活性,采用正交设计进行提取条件优化,并与水蒸气蒸馏法提取精油速度以及精油组分进行比较,同时对微波法提取精油及其主要组分的体外抗氧化活性及抑菌活性进行评价。结果表明:在浸泡时间3 h,料液比1∶1(g∶mL),提取时间40 min,微波功率540 W的最佳提取条件下,提取得率为1.04%。由GC-MS分析可知,微波法提取兴安百里香精油主要成分为百里香酚(52.52%)、α-萜品烯(12.72%)和对伞花烃(8.24%),提取的精油主要组分种类与水蒸气蒸馏法相一致。各主要组分中,百里香酚的DPPH·清除活力最强(IC_(50),473.63 mg/L),且β-胡萝卜素漂白抑制率也最高(IC_(50),250.91 mg/L),仅对伞花烃无抗氧化活性。体外抑菌实验表明:兴安百里香精油3种主要组分中百里香酚抑菌活性最强,α-萜品烯次之,对伞花烃无抑菌活性。百里香酚对各测试菌种均表现出一定的抑制活性,其中抑制活性最强的为枯草芽孢杆菌,抑菌圈直径为16.85 cm,最小抑菌浓度(MIC)为0.23 g/L。 相似文献
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采用超临界CO2流体萃取法(SFE-CO2)和水蒸气蒸馏法(SD)从川桂叶中提取挥发油,利用气相色谱-质谱联用技术,分析了挥发油的化学组成,并进行了比较.结果表明:两种方法所得挥发油存在较大差别,超临界CO2流体萃取得到挥发油的产率为1.6%,主要成分是香豆素(32.5%),芳樟醇(19.9%),棕榈酸(10.4%),而水蒸气蒸馏法得到挥发油的产率为0.9%,主要成分是芳樟醇(69.0%)、丁香烯(4.6%)、氧化丁香烯(2.7%). 相似文献
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《中南林业科技大学学报(自然科学版)》2016,(11)
以湘西产的香桂叶为原料,采用超声-微波协同萃取法对香桂叶油的提取工艺进行了研究。以水为萃取溶剂,对提取次数、微波功率、提取时间、液固比、氯化钠浓度等影响萃取的因素进行了单因素实验。在单因素实验结果的基础上,提取1次,对各因素进行正交实验优化,得出了香桂叶油的萃取优化工艺条件:微波功率75W,提取时间30 min,液固比10(m L/g),氯化钠浓度为4%。与传统的水蒸气蒸馏法相比,超声-微波协同萃取不仅大大缩短了蒸馏时间,而且香桂叶油的提取率从2.411%提高到3.288%。通过GC-MS检测,该工艺下香桂叶油中黄樟油素的含量可高达98.09%。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
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Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and
also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the
amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter
bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K
was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed
significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week−1 for leaves and from 0.0225 to 0.0633 week−1 for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed
during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly
between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species
provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient
enrichment capacity and slower decomposition rates which would minimize leaching losses.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Astra Zaluma Lauma Bruna Darta Klavina Natalija Burnevica Kristine Kenigsvalde Andis Lazdins Talis Gaitnieks 《Forest Pathology》2019,49(6)
Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):118-130
The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
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本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
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Steven Maranz Amadou Niang Antoine Kalinganire Djeneba Konaté Bocary Kaya 《Agroforestry Systems》2008,72(3):231-239
Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional
data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral
contents and B1 and B2 vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising
germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B1 88 mg 100 g−1, B2 187 mg 100 g−1, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal
diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties
to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations. 相似文献
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《Wood material science & engineering》2013,8(2):76-84
Abstract Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists. 相似文献