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Steenkamp V 《Fitoterapia》2003,74(6):545-552
Phytomedicines are becoming more popular all over the world. Prostate cancer patients and those with benign prostatic hyperplasia are increasingly exploring the use of complementary alternative medicine especially due to the risk of mortality and long-term morbidity associated with surgical procedures. The incidences of prostate diseases are continually rising and the effect of phytomedicines already tested do provide relief, are well comparable with that of traditional forms of treatment. This paper reviews the phytomedicines used in Africa, Western countries and China as a treatment of benign prostatic hyperplasia, prostatitis and prostate cancer. Herbals which hold potential promise are mentioned, although much research is still required. 相似文献
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We present a new approach for selecting seed sources of Eucalyptus to be grown on saline land. We evaluated our method using 22 seed sources, 11 tree-form species and 11 mallee-form species.
We found that the commonly used strategy of selecting seed sources on the basis of average productivity was inappropriate,
as average productivity was poorly correlated with the relationship between productivity and salinity that was actually observed.
Using our new approach, we categorized seed sources as salt-sensitive or salt-tolerant based on the strength of the observed
relationship between salinity and productivity. Seed sources defined as sensitive were associated with relatively large (−24.8
to −64.2%) productivity losses, while the changes in productivity for tolerant seed sources ranged from −17.1 to 10.5%. On
average, reductions in height due to increased salinity were about 30% greater for sensitive seed sources than tolerant ones,
although the effect was smaller for mallee-form and greater for tree-form seed sources. The difference between sensitive and
tolerant seed sources was similar after 1, 2 and 4 years of growth. 相似文献
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王珊子 《绿色中国(综合版)》2006,(8):66-68
“民以食为天”,“人命关天”,这两句古话阐明了食品安全无以复加的重要性。实际上,食品安全的重要性还远不止于此,这个问题不仅关系到人的健康和生命,而且关系到经济发展、社会稳定,乃至公民对整个社会和政府的信心。[编者按] 相似文献
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《Journal of Sustainable Forestry》2013,32(3-4):307-316
Concerns for maintaining biodiversity have led to the adoption of ecosystem management as the paradigm for federal land management. This approach will identify desired future conditions as the goal for management, based on ecological objectives for a given landscape. Some management efforts attempt to identify desired future conditions based on existing successional stages as defined by a classification of overstory vegetation types. Such an approach ignores most of the underlying ecological parameters of the landscape, and is inadequate for identifying past disturbance regimes and future successional pathways. An assessment of desired future conditions based on an ecological classification system is essential to overcome these inadequacies. The strategy proposed in this paper uses an appropriate ecological land classification, based on either ecological land types or habitat types, included in a broader hierarchical classification system. It also uses a vegetation map of existing overstory vegetation. These two maps are overlaid to generate polygons of ecological units that can then be used to create an ecosystem diversity matrix. Each polygon (stand) can be evaluated as to its composition and structure relative to its possible placement within the ecosystem diversity matrix through comparisons with historical ranges of variability. The overall ecosystem diversity matrix can then be examined in terms of the distribution of successional stages within each habitat type or ecological land type. The goal should be to maintain at least adequate ecological representation of all successional stages within each habitat type that occurred historically, based on past disturbance regimes. Adequate ecological representation is defined as sufficient size and distribution of inherent ecosystems to maintain viable populations of all endemic species dependent on these ecosystems. This approach can maintain and enhance regional biodiversity, but also maintain flexibility in land management options. 相似文献
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王珊子 《绿色中国(A版)》2006,(15):66-68
“民以食为天”,“人命关天”,这两句古话阐明了食品安全无以复加的重要性。实际上,食品安全的重要性还远不止于此,这个问题不仅关系到人的健康和生命,而且关系到经济发展、社会稳定,乃至公民对整个社会和政府的信心。 相似文献
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12个桃品种的花芽休眠需冷量和开花需热量 总被引:3,自引:0,他引:3
在浙西南地区研究12个桃品种花芽休眠需冷量和开花需热量生态指标.犹他模型测定结果显示:12个桃品种中,花芽休眠需冷量低的品种为春蜜、超红、中油11号、中油7号、中油4号,约为550~650 cu;其次是丽油5号、仓方早生、燕红、丽油3号、早凤凰,约为650~ 800 cu;需冷量高的品种为新川中岛和赤月,约为900~ 950cu.同一地区不同品种需热量差异较大,同一品种年际间差异相对较小.以生长度天模型试验结果表明:开花需热量低的品种为赤月和丽油3号,大约400 ~ 500 d·℃;其次是新川中岛,大约500~600 d·℃;春蜜、丽油5号、早凤凰、中油4号、中油7号、仓方早生和燕红大约600 ~ 700 d·℃;需热量较高的是中油11号和超红,约为700~800 d·℃.12个桃品种花芽休眠需冷量与开花需热量之间呈乘幂函数曲线显著负相关. 相似文献
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Summary Effects of moisture content on bending strength and section capacity have been studied assuming that strength properties are linearly related to moisture content below the fiber saturation point. The models developed using the linear strength vs. moisture content relationships are compared with quadratic models developed earlier. The linear representation of strength variation with moisture content leads to predicted member bending capacity relationships which show that increases in member bending strength with moisture content will compensate for section property decreases at all bending strength property levels. Comparisons of bending strength and bending capacity models show that the two modelling approaches lead to similar predicted member performance. Simplified procedures are provided for adjusting member bending strength for moisture content which are suitable for materials properties codes or standards. 相似文献
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R. I. Muetzelfeldt 《Agroforestry Systems》1995,30(1-2):223-234
There are a number of problems with conventional methods for implementing models of agroforestry systems, including the difficulties of building, modifying and understanding them. One way of addressing these problems is to adopt a modular modelling approach, in which a model is constructed by linking a number of submodels, which in turn may consist of smaller computational units.This paper presents a basic framework for the design of a modular modelling approach suitable for agroforestry modelling. This approach is based on a close correspondence between the notion of module in modelling and of subroutine in a programming implementation of a model, so that selecting and linking modules is analogous to choosing and issuing calls to subroutines. This approach has the potential for enabling the complex modelling structures that are required for agroforestry modelling, such as spatial aspects and the representation of individual trees, to be handled in a consistent and uniform manner.The approach requires that subroutines should be held as symbolically-represented structures, rather than just source code in a programming language, so that they can be referenced as discrete units, and internally modified by symbol-processing operations. It is shown that the logic-programming language Prolog is well-suited to the task of representing subroutines in template form, ready to be fleshed out and combined into a single program in response to the selections made by a user. Prolog's suitability for the development of a user-friendly model design interface is also discussed, enabling models to be constructed simply by selecting options from a menu of design choices. 相似文献
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Summary A system was developed for grouping tropical wood species for kiln drying based on similar estimated drying times. Six tropical species were subjected to drying and water soaking tests; variables were test temperature and specimen thickness. Soaking time, specimen thickness, and test temperature were used in an empirical model to predict drying times. The capability of the model to predict drying times was considered acceptable based on an adjusted coefficient of determination equal to 0.929 and an average error of 14 percent. The overall capability of the method proposed for grouping tropical hardwoods for drying is considered promising and worthy of further investigation. 相似文献
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以细木工板基材用杉木(Cunninghamia lanceolata)为研究对象,对杉木锯材进行小试干燥试验,依据GB/T 6491-2012标准,分析干燥缺陷,制定干燥基准,获得优化小试干燥工艺;开展杉木锯材干燥工艺优化中试试验,并将采用优化小试干燥工艺和优化中试干燥工艺的杉木锯材与原企业干燥工艺的杉木锯材进行对比。结果表明,细木工板基材用杉木属于易干锯材,在干燥过程中易出现开裂和翘弯变形。采用优化中试干燥工艺后,杉木锯材的干燥时间约48 h,比企业原干燥工艺时间缩短约33%,且干燥质量等级达到GB/T 6491-2012标准一级要求,满足细木工板基材质量要求。优化后的细木工板基材用杉木干燥工艺,在确保干燥质量的前提下,较显著提高干燥效率,降低干燥成本。 相似文献
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A convenient model type for simulating the dynamics of uneven-aged and uneven-sized stands of Finland is individual-tree model.
This is because the stand structures are complex due to the presence of several tree species and irregular size distributions
of trees. The required minimum set of models in this approach consists of species-specific individual-tree diameter increment
models, individual-tree survival models, and ingrowth models. The development of these models needs data in which the diameter
and survival of each tree of the sample plots is known for at least two time points. For this, the trees need to be numbered,
which is tedious in uneven-aged forests due to the great number of small trees and the continuous ingrowth process. This study
proposes a modelling approach that fits the above models but requires only the diameter distributions of the plots in the
beginning and at the end of the measurement interval. The method uses non-linear optimization to derive such values for model
parameters that, when the models are applied to the initial diameter distribution, the simulated stand development results
in a diameter distribution which agrees with the measured ending distribution. The study showed that the method produces similar
models and model parameters as regression analysis. Since the method is less demanding in terms of modelling data, it brings
new data sets available for modelling the dynamics of uneven-aged stands and reduces the cost of collecting new data. The
models fitted by the proposed optimization method were rather similar to the models developed earlier for Finnish uneven-aged
forests. 相似文献