共查询到20条相似文献，搜索用时 62 毫秒
1.
2.
采用正交试验和单因素试验相结合的方法对保加利亚玫瑰精油提取工艺进行了研究，得出的最佳工艺参数为：液料比4：1、蒸馏时间4h、蒸馏速度200mL／h(为每小时蒸出蒸馏器容积10％的馏出液)、装料量为蒸馏器的75%。蒸馏时间为最主要影响因素．其次是蒸馏速度．最后是液料比；玫瑰花的粉碎状况和蒸馏时馏出液是否回流对出油率无显影响；玫瑰花的部位不同．其精油含量亦不相同，应采用全花蒸馏的方法生产精油；盐水质量分数2．5%可显提高出油率。 相似文献
3.
岩桂叶精油蒸馏出油率及化学成分变化的研究 总被引：1，自引：0，他引：1
对岩桂叶精油在蒸馏过程中的出油率及化学成分变化情况进行了研究。在常压水上蒸馏情况下，岩桂叶的蒸馏出油率达到３．９２％，其出油量的８７．７６％集中在蒸馏前期的６０ｍｉｎ内，以后随蒸馏时间的进行逐渐下降。岩桂叶精油的主要化学成分为１１个，以黄樟油素为主，其含量达到９５％以上。各化学成分在蒸馏过程中的变化规律是：黄樟油素和芳樟醇的含量随蒸馏时间的进行逐渐减少；其它化学成分的含量均随蒸馏时间的进行而逐渐增 相似文献
4.
5.
6.
玫瑰花保藏方法与精油得率关系的研究 总被引：2，自引：0，他引：2
根据实际条件对玫瑰花的保藏方法进行了研究,寻找出了几种有效的保藏方法.包装袋A保藏玫瑰花,温度变化小,花香、花色好,是一种既经济又简便易行的短时间保藏玫瑰花的好方法,可保藏24 h;室内摊放,散热好、玫瑰花不发热,在放置6 h后因后熟作用,出油率比立即提取提高20%,但随着时间的延长,香气不断向空气中散失,出油率下降,所以室内摊放保藏鲜花时间不宜过长,最好不要超过6 h;冷冻能长时间地保藏玫瑰花,出油率亦不受影响;盐渍可以较长时间地保藏玫瑰花,15%的加盐量效果较好. 相似文献
7.
<正> 西双版纳地区1974年以来种植的6,000余亩依兰香,规已陆续开花投产。1984年全州产依兰香油268公斤,农民开始有了经济收益。但如何提高依兰鲜花的出油率,如何生产出质量好的依兰香精油,已成为当前的重要技术问题。事实上,依兰香的品种、花的成熟度及采花的季节、天气和时间都会影响精油的产量和质量。我们针对上述影响因素,进行了一系列对比试验,取得了一些初步结果,现初报如下。 相似文献
8.
蒸馏时间与互叶白千层精油主要化学成分及出油率关系的研究 总被引：9，自引：1，他引：9
蒸馏的持续时间是影响互叶白千层精油质量及出油率的重要因素之一。对不同蒸馏时间段收集的互叶白千层精油的化学成分及出油量进行了分析研究。结果表明，随着蒸馏时间段的延长，互叶千层芳香油的主要化学万分的含量及其出油量均下降，在0-120min内，出油率已超过98%,120-150min阶段其出油率不到2%。而高沸点的环烯烃及其醇类却随着蒸馏时间的增加而增加。因而可能通过控制蒸馏时间，提高互叶白千层精油的质量，同时可以降低能耗。 相似文献
9.
10.
本文对7个史密斯桉无性系桉叶的出油率进行了测定,对其精油成份进行了分析。结果表明：在7个史密斯桉无性系中,出油率在3．0％以上的有17号、2号、8号,出油率分别达到3．67％、3．61％、3．20％,出油率分别超过史密斯桉实生苗91．43％、88．62％、67．39％,分别超过蓝桉实生苗131．97％、128．18％、102．29％,具有较高的精油得率;精油成份分析表明：在7个史密斯桉无性系中1,8-枝叶素含量在80％以上的有4号、8号、7号、1号无性系,分别为82．85％、80.31％、80．26％、80．05％;以1,8-桉叶素产量为首选指标的综合分析表明,出油率是1,8-桉叶素产量的关键因素,出油率与1,8-桉叶素产量呈正相关。 相似文献
11.
《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
12.
《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
13.
《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
14.
《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
15.
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
16.
《Scandinavian Journal of Forest Research》2012,27(2):131-138
The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided. 相似文献
17.
18.
《Scandinavian Journal of Forest Research》2012,27(5):472-479
Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken. 相似文献
19.
Srisuda Thippayarugs Banyong Toomsan Patma Vityakon Viriya Limpinuntana Aran Patanothai Georg Cadisch 《Agroforestry Systems》2008,72(2):137-148
In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic
or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts
(stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea
(Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content
as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest
N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized
to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea,
largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for
N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant
components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N
released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures
were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality
components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in
the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols.
Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest
age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its
components are mixed. 相似文献
20.
A. Rigueiro-Rodríguez M. R. Mosquera-Losada E. Gatica-Trabanini 《Agroforestry Systems》2000,48(3):245-256
The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste
disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization,
(2) milk sewage sludge at 40 kg N ha−1 target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two
pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha−1. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1); (2) Lolium perenne L. var. Tove (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea
(Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m2, with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect
on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage
sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but
affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral
systems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献