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1.
AKEROYD, J. R. & WALTERS, S. M. 1987. Flora Europaea: the background to the revision of Volume One. Flora Europaea, published 1964-80, is a synthetic catalogue of Europe's vascular plants. Its publication has provided a relatively stable taxonomic and nomenclatural framework for the study of the flora of the continent, and has stimulated much further research and publication. The revision of the first volume of Flora Europaea, at Reading University, has been necessary in order to accommodate new information, to satisfy the continued demand for a complete Flora of Europe, and to update the original text. The revision is being carried out in cooperation with other European and Mediterranean floristic projects.  相似文献   

2.
The use of chemically defined artificial diets has allowed researchers to examine questions within nutritional ecology about how macronutrients affect life‐history traits and resource‐based trade‐offs. Using a chemically defined diet, it is possible to manipulate both the total nutritional content and the ratio of macronutrients (i.e., proteins, carbohydrates, or lipids) within the diet. Studies using the geometric framework have made use of these diets to examine lifespan, fecundity, and immune responses. Here, we develop an artificial diet suitable for rearing lepidopteran larvae. We created diets with three proportions of non‐nutritive material (30, 50, and 70% indigestible cellulose) relative to protein and carbohydrate macronutrients, and compared these to standard wheat bran laboratory diet. We then examined the effects of variable nutrient content on lifespan and development time in Plodia interpunctella Hübner (Lepidoptera: Pyralidae). The artificial diets supported development (almost) as well as bran‐based laboratory diets. Total nutrient content affected development time: females that fed on the diet with the highest nutrient content took the longest time to reach eclosion. We also found evidence to support dietary restriction, with larvae receiving the fewest nutrients having the longest lifespan as adults. These findings are indicative of the usefulness of this diet as a tool to further investigate the effects of nutrient content and macronutrient imbalance on resource‐based trade‐offs and life‐history traits.  相似文献   

3.
4.
为满足小型猪培育数字化管理需要开发的"中国实验用小型猪信息管理系统"由育种管理、饲养管理、群体监测和操作规程等14个模块组成,其中最具特色的部分是育种管理和群体监测模块。为确保数据库质量,育种管理模块创建了以级联表和单选框勾选、个体号和群体类型自动生成的个体信息录入方式;根据近交系和封闭群建系规则创建了自动配种模块,基于系谱生成配种计划表,结合发情记录、产仔记录等实现繁殖管理数字化。群体监测模块由生物学特性、微生物和寄生虫质量控制、遗传质量控制三个部分组成,是建立高品质实验用小型猪群体的信息保障。  相似文献   

5.
To meet nutritional needs, primates adjust their diets in response to local habitat differences, though whether these dietary modifications translate to changes in dietary nutrient intake is unknown. A previous study of two populations of the mountain gorilla (MG: Gorilla beringei) found no evidence for intraspecific variation in the nutrient composition of their diets, despite ecological and dietary differences between sites. One potential explanation is that nutritional variability in primate diets requires greater ecological divergence than what was captured between MG sites, underpinning environmental differences in the nutrient quality of plant foods. To test whether Gorilla exhibits interspecific variation in dietary composition and nutrient intake, we studied the composition and macronutrients of the western gorilla (WG: Gorilla gorilla) staple diets and compared them with published data from the two MG populations. We recorded feeding time and food intake of four adult female WGs from one habituated group over a period of 11 months (December 2004–October 2005) at the Mondika Research Center, Republic of Congo, allowing for assessment of seasonal patterns of nutrient intake. Staple diets of WGs and MGs diverged in their dietary and macronutrient composition. Compared to MGs, the staple diet of WGs (by intake) contained higher proportions of fruit (43%) and leaf (12%) and a lower proportion of herb (39%), resulting in a higher intake of total nonstructural carbohydrate and fiber and a lower intake of crude protein. Staple gorilla fruits and herbs differed in nutrient quality between sites. Gorillas exhibit nutritional flexibility that reflects ecological variation in the nutrient quality of plant foods. Since dietary quality typically affects rates of growth and reproduction in primates, our results suggest that interspecific differences in nutrient intake and food quality may shape differences in gorilla nutrient balancing and female life history strategies.  相似文献   

6.
Gower's (1977) method for the canonical analysis of asymmetric matrices (CAA) where the same entities index both the rows and the columns is described. This technique displays the indexing entities in a series of orthogonal planes of decreasing importance in such a way as to preserve the pattern of the asymmetry between them. The analysis is applied to a half-diallel experiment and to some leaf-overtopping data, both from a study of the control of relative abundance of perennials in chalk grassland. The results suggest a common source for the asymmetry in the very different interference and overtopping data, namely that of leaf height. It is concluded that relative abundance in the field may be determined, in part, by leaf height through aboveground interference between plants.Nomenclature follows Tutin et al., 1964–1980. Flora Europaea, Vols 1–5. Cambridge University Press, Cambridge.I am particularly indebted to the Nature Conservancy Council for permission to carry out the field experiment on the Aston Rowant N.N.R., and to do field work at Castle Hill N.N.R.We are grateful to R. A. Kempton for permission to use his methodology in the analysis of the half-diallel experiment prior to publication. This work was carried out while J.M. was in receipt of a Research Studentship from the Natural Environment Research Council, and L.G. was in receipt of an internal Research Studentship from Trinity College, Cambridge.  相似文献   

7.
1. Cannibalism is considered an adaptive foraging strategy for animals of various trophic positions, including carnivores. However, previous studies on wolf spiders have questioned the high nutritional value of cannibalism. We therefore analysed two different aspects of nutritional quality of conspecifics in the wolf spider Pardosaprativaga: their value for survival, growth and development; and the growth efficiency of feeding on conspecifics. We also measured the propensity for cannibalistic attacks and the consumption rate of conspecifics in an experiment where hunger level and nutrient balance were manipulated. In all experiments, cannibalism was compared with predation on fruit flies as control prey. 2. The growth experiment gave ambiguous results regarding the nutritional quality of conspecifics. Spiders on pure cannibalistic diets split into two distinct groups, one performing much better and the other much worse than spiders on fruit fly diets. We discuss the possibility that the population is dimorphic in its cannibalistic propensity, with the latter group of individuals showing a high level of inhibition against cannibalistic attacks in spite of a high nutritional value of cannibalism. 3. The food utilization experiment confirmed the high nutritional quality of conspecifics, as cannibalistic spiders had the same growth rate as spiders fed insect prey in spite of a much lower consumption rate. 4. Inhibition against cannibalistic attacks was demonstrated in medium-sized juveniles: only half of the spiders attacked a prescribed victim of 50% the size of their opponents, and the latency for those that did attack was more than half an hour, compared with a few minutes for spiders fed fruit flies. 5. Nutrient-imbalanced spiders utilized an alternative insect diet less efficiently than balanced spiders, whereas no difference was present in efficiency of utilizing conspecifics. This result indicates that spiders can remedy at least part of a nutrient imbalance through cannibalism. 6. As spiders can escape nutritional imbalance as well as restore energy reserves through cannibalism, we predicted both nutrient imbalance and hunger to stimulate cannibalism. This prediction was confirmed only with respect to hunger. Nutrient-imbalanced spiders had reduced cannibalistic consumption, perhaps due to lowered predatory aggressiveness as a result of bad condition.  相似文献   

8.
9.
Mass customization (MC) as a business strategy is designed to simultaneously compete on two rival competitive priorities—the price and customization level of a product. MC academics and experts have gone a step further. They suggest that MC is a unique strategy whose implementation promises across-the-board improvement in all four of the competitive priorities (price, quality, flexibility, and speed) simultaneously. Its growing adoption by businesses in recent years, the steep rise in success stories associated with MC, and the voluminous body of publications in a short period of its existence have created a need to study the directions, trends, application potential, and research strategies embedded in these publications. Accordingly, this paper studies and analyzes the trends and directions of the research published in 1,124 MC publications that have appeared in journals and magazines since the inception of the term mass customization in 1987 by Stan Davis in his classic book Future Perfect. Statistical trend analyses are conducted to study the vitality and health of the field of MC using number of publications and number of publication outlets and their respective trends. The publication outlet data conform to an S curve, establishing maturity of the MC field. The publication data show that the MC field has passed through four stages of growth: incubation or slow (1987–1992), exponential (1993–2003), stable and matured (2003–2005). There is a slight dip in 2006 in terms of publication outlets; there are, however, confirmatory factors that indicate that the dip in 2006 may be an outlier. This paper also suggests developing a clear understanding of the value and type of research embodied in MC publications through three types of taxonomic analyses. The frameworks for all three taxonomies are set forth, two of which have been previously employed in other areas of OR/MS (Reisman and Kirschnik, Oper Res 42(4):577–588, 1994; Oper Res 43(5):731–740, 1995): The first taxonomic framework first classifies the paper as a theory paper or an application paper. At the second stage, the application content of the publication is determined based on a five-point scale ranging from simple modeling of the real world to bona fide real-world application. The second taxonomic framework suggests usage of a taxonomy comprised of seven distinct types of research strategies. The former analysis provides important information about the application worthiness of the MC publications and hence their usefulness to the real world. The second analysis provides information about the type of research strategies used by MC researchers, which, in turn, allows drawing conclusions about the quality and rigor of such research. The third taxonomic framework suggested recommends classification of all publications among multi-level containers based on the disciplines that intersect with MC and their branches.  相似文献   

10.
北美田鼠亚科啮齿动物营养生态学研究进展   总被引:4,自引:5,他引:4  
刘季科  王溪 《兽类学报》1991,11(3):226-235
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11.
Aim Soil nutrient content plays a key role in plant growth through mineral nutrition and toxicity. Its impact on plant species and community distribution is studied on a large geographical scale through surrogates like topography or geology. We investigated the importance of soil pH and C:N ratio, as direct nutritional gradients, to determine, with climatic factors, the spatial distribution of plant communities over large territories. Location We studied the distribution of six beech habitats of the NATURA 2000 network throughout France (550,000 km2). Methods Models were calibrated with 2108 floristic plots classified in the NATURA 2000 system and including climatic and topographic variables and soil nutritional measurements carried out in a laboratory. Logistic regression was used to model habitat distribution according to environmental variables. Climatic layers, a digital elevation model and maps of soil pH and nitrogen content, created using plant indicator values and large floristic databases, were used to map the sites suitable for beech communities. Distribution models were evaluated with an independent set of 2091 phytosociological plots. Results pH and nitrogen supply were the key distribution drivers for four of the six beech communities on a national scale. Their use in the distribution models distinguished within homogeneous climatic territories a gradient of nutritional conditions from acidic areas, suitable for nutrient‐poor beech communities, to calcareous areas suitable for nutrient‐rich ones. Predicted maps of beech habitats fit the spatial distribution of validation plots. Main conclusions Soil pH and nitrogen supply strongly improve predictions of forest community distribution carried out with climatic variables on a broad geographical scale. They allow delineation of areas with nutritional conditions suitable for each community, as well as the realization of predictive high‐resolution maps over large areas useful for sustainable and conservation management. Nomenclature Tutin & Heywood (2001 ) Flora Europaea. Cambridge University Press, Cambridge.  相似文献   

12.
Robin Kennish 《Oecologia》1996,105(1):22-29
The tropical rocky shore crab Grapsus albolineatus feeds primarily on filamentous algae but eats animal matter whenever it is available. During the summer the crab's diet switches to encrusting algae due to a die-off of filamentous algae. As a result of the switch the nutrients in the diet of the crab vary seasonally and may influence the fitness of the crab. Maintenance, growth, reproductive performance and nutrient storage of crabs were examined under four dietary regimes of increasing nutritional value ranging from low organic to high protein content. The nutritional quality of these diets significantly affected crab survival and moulting. Crabs fed on the nutritionally superior diet of algae and meat exhibited enhanced growth, higher levels of energy in the reproductive organs and stored more energy in the hepatopancreas than did individuals on the shore and crabs fed only on algal diets in the laboratory. Filamentous algae were a better food source than other algae, resulting in fewer deaths and superior levels of maintenance and growth. Growth and maintenance can occur on a pure algal diet, but reproductive performance and nutrient storage require some degree of added nutrients in the form of animal matter in the diet. Crabs fed coralline or foliose algae had higher mortality and fewer successful moults than crabs fed the other two diets. The fitness of G. albolineatus appears to be limited by the amount of extra nutrients obtained from animal matter. The opportunistic consumption of animal material in the form of carrion, or of animals associated with dietary algae, could be a key factor in the reproductive success of this crab.  相似文献   

13.
BACKGROUND: Current knowledge about the optimal energy and nutrient supply for common marmoset monkeys (Callithrix jacchus) is scarce, and more information is needed for establishing the underlying nutritional concepts for facilitating longevity of this species as laboratory animals for biomedical research. Methods: Two feeding experiments were conducted to yield fundamental data about feed acceptance, real feed intake, and feed preferences under laboratory conditions. Newly developed feeding concepts for marmoset monkeys were also examined in preliminary investigations to compare the outcomes with those of a commercial pelletized mixed feed. RESULTS: The first experiments showed preferences for main protein sources in the diets studied, specifically that plant proteins are more accepted than fish meal or egg protein as the main protein source. Several aroma supplements did not modify the acceptance and feed intake markedly. Conclusions: The newly developed feeding concept yielded promising preliminary data for long-term studies of energy and nutrient supply under laboratory conditions. However, studies of the fundamental requirements are still needed.  相似文献   

14.
报道了产于中国二叠纪煤核中的 3种具解剖构造的鳞木类叶 ,它们都具双木质部束 ,与似封印叶属 (Sigil lariopsisScott)特征一致。与该属已有种进行了对比 ,确认它们为 3个新种 :产于山西太原西山煤田太原组上部 7号煤层 (早二叠世早期 )煤核中的山西似封印叶 (Sigillariopsisshanxiensissp .nov .)和太原似封印叶 (S .taiyuanensissp .nov .)以及产于贵州水城矿区汪家寨组 1号煤层 (晚二叠世晚期 )煤核中的贵州似封印叶 (Sigillariopsisguizhouensissp .nov .)。根据煤核中共生的鳞木类植物其他器官以及欧美植物区鳞木类植物的研究资料推断 ,它们可能属于封印木属 (SigillariaBrongniart)的叶。在国外 (主要是欧美植物区 ) ,封印木属植物主要分布于石炭纪 ,见于二叠纪的封印木很少。华夏植物区的封印木属过去很少发现 ,其叶和生殖器官均未报道过。本文是首次报道华夏植物区具解剖构造的封印木属的叶 ,它们的发现不仅丰富了华夏植物区封印木属植物的内容 ,而且对于研究封印木属的演化以及华夏植物区与欧美植物区鳞木类植物之间的关系也具有重要的意义。  相似文献   

15.
The behavioral consequences of pregnancy in goats were studied to test the hypothesis that pregnant females on rangeland select a diet richer in nutrients once the demands of gestation increase, and that nutrient content in goat diets changes with the grazing season. A total of 12 mature mixed breed goats either pregnant (n = 6) or non-pregnant (n = 6) were used during the dry period (February to May). Dietary samples obtained from the oral cavity of grazing goats (restrained with a short light rope permanently tightened around their neck) were used for chemical analyses. Across months, pregnant goats selected diets higher (P < 0.01) in crude protein (CP) than non-pregnant goats; this nutrient did not meet the requirements of late gestating goats. Pregnant goats made use of less (P < 0.01) fibrous feeds than non-pregnant goats. In order to cope with changing nutrient demands for pregnancy, goats adjusted their diet by increasing the selection of plants with 32% higher calcium content compared to forages selected by non-pregnant goats. The physiological state of goats did not alter the levels of phosphorus (P), magnesium (Mg) and sodium (Na) in their diets; these minerals were adequate to meet the demands of pregnancy. There were no effects of physiological state on concentrations of copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe) in the goat diets during the dry season, with levels adequate for sustainability of pregnancy. Pregnant goats did not seek forages lower in tannins, alkaloids, saponins and terpenes. It was concluded that to cope with increasing pregnancy costs, goats adjusted their diets increasing selection of forages or plant parts with high nutritional value to maximize their net nutrient budget.  相似文献   

16.
报道了产于中国二叠纪煤核中的3种具解剖构造的鳞木类叶,它们都具双木质部束,与似封印叶属(Sigillariopsis Scott)特征一致.与该属已有种进行了对比,确认它们为3个新种:产于山西太原西山煤田太原组上部7号煤层(早二叠世早期)煤核中的山西似封印叶(Sigillariopsis shanxiensis sp. nov.)和太原似封印叶(S. taiyuanensis sp.nov.)以及产于贵州水城矿区汪家寨组1号煤层(晚二叠世晚期)煤核中的贵州似封印叶(Sigillariopsis guizhouensis sp.nov.).根据煤核中共生的鳞木类植物其他器官以及欧美植物区鳞木类植物的研究资料推断,它们可能属于封印木属(Sigillaria Brongniart)的叶.在国外(主要是欧美植物区),封印木属植物主要分布于石炭纪,见于二叠纪的封印木很少.华夏植物区的封印木属过去很少发现,其叶和生殖器官均未报道过.本文是首次报道华夏植物区具解剖构造的封印木属的叶,它们的发现不仅丰富了华夏植物区封印木属植物的内容,而且对于研究封印木属的演化以及华夏植物区与欧美植物区鳞木类植物之间的关系也具有重要的意义.  相似文献   

17.
A study was designed to (a) identify sources and sinks of N in the maize (Zea mays L.) shoot, by estimating net N fluxes for each of seven parts of the shoot, (b) determine effects of N entering the plant upon fluxes of N absorbed before reproductive growth, and (c) determine the effects of the opaque-2 gene on N fluxes in the maize shoot during early reproductive growth. Plants of a maize hybrid (Pioneer 3369A) and its opaque-2 counterpart (Pioneer L3369) were grown in a greenhouse using nutrient solution/sand culture, with NO3 as the N source during the vegetative growth phase. Beginning at the time of pollination, the same nutrient regime was continued, except that some plants received no N, and others received 3.75 millimolar 15N as NO3-N.

Stalk and leaves were found to be primary N sources for the grain, while shank, husk, and cob acted first as N sinks, then as N sources during reproductive growth. Net fluxes of N for each plant part were estimated by calculating the first derivatives of regression equations used to fit data for N contents of each plant part as functions of time. All parts of the shoot were sinks for exogenous N (absorbed after pollination). Thirty-six days after pollination, the grain contained 60% endogenous N (absorbed before pollination) when 3.75 millimolar NO3-N was supplied after pollination. Rates of total N influx to the grain were identical whether or not N was supplied in the nutrient solution during reproductive growth. At 36 days after pollination, less N had accumulated in the grain of the opaque-2 genotype, but otherwise there were no differences in N contents or dry weights of the shoots due to the opaque-2 gene. Absence of N from the rooting medium significantly affected N fluxes throughout the shoot during reproductive growth, but there were no detectable effects of the opaque-2 gene on N fluxes in parts of the plant other than the grain.

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18.
Xylem sap composition of spruce is influenced by several factors, such as the sampled organ, the sampling period, the availability of soil nutrients, and the soil water potential. Based on literature data and ongoing investigations carried out with adult trees, we present an overview on the main factors influencing xylem sap concentrations of Norway spruce. Direct measurements of nutrient fluxes in the xylem sap are then used to suggest a general scheme of mineral element cycling within adult trees. In Norway spruce (Picea abies Karst.), nutrient concentration in the xylem sap was higher in twigs and fine roots compared to the bottom of the trunk, the highest concentrations beeing observed in spring during the shoot elongation. Xylem sap concentrations were higher in spruce growing at nutrient rich sites than at poor sites. The combination of twig and trunk xylem sap analysis, together with xylem flow measurements in the trunk during the course of a vegetation period allowed the quantification of mineral fluxes via xylem sap flow in the trunk and twigs. These results were compared to gross mineral uptake measurements at the same site. Ca flux in the trunk xylem sap was lower than the gross uptake of Ca. Mg flux in trunk sap was approximately equivalent to Mg gross uptake whereas P and K fluxes in trunk sap were much higher than the gross uptake. Fluxes of Ca, Mg, K and P in the twig sap were much higher than that in trunk sap. Data suggest that internal cycling is responsible for a large part of the nutrient fluxes in the xylem sap of the crown. Xylem sap composition thus appears to be a tool which can complement other sources of information on mineral uptake and cycling in adult spruce  相似文献   

19.
肖强  胡聃  郭振  王天祥  谭宏 《生态学报》2011,31(19):5475-5483
从扩展建模技术、系数调整2条线索回顾国内外的水资源投入产出研究进展, 并讨论水资源的投入产出研究的不足和发展趋势。因为水资源投入产出表反映的是水资源与经济结构的关系,如果研究人员自己编制一张水资源投入产出表是不容易的事情。通常情况下都是以研究地域的投入产出表为基础,与其他模型相结合来研究水资源投入产出,但是水资源投入产出建模技术因为数据的限制而只能建立年度模型,具有很强的前提假定,使得投入产出建模技术缺乏灵活性,因而在运用中有对模型改进的必要。水资源投入产出扩展建模技术在这些方面就分别形成了与地区投入产出表结合的投入产出建模技术、与水资源供给相结合的投入产出扩展建模技术、与延长表结合的投入产出扩展建模技术。时效性缺乏一直就成为影响IO模型研究的最主要的瓶颈之一,为此,对各种用于建立新的 IO 表技术的研究一直受到普遍的重视。目前, IO 表系数调整方法已从消耗系数不变的系数调整方法、以RAS为代表的比例法, 发展到多种手段相结合的优化法。算法的改进和求解非线性规划问题的大量计算机软件的出现使得非线性优化模型得到了广泛的应用。  相似文献   

20.
In order to cope with the increasing number of publications on the separation of enantiomers by chromatography on a chiral stationary phase, the graphical molecular database CHIRBASE was created. In the present state, the database package covers information (structural, bibiographic, and chromatographic data) on liquid-, supercritical fluid-, and gas chromatography; other methods will follow. CHIRBASE, running on the MDL software Chembase®, meets the requirements of contemporary information management in the chemical and pharmaceutical industry. (Detailed information including a demo-version of each part of CHIRBASE can be obtained from the authors on request.) © 1993 Wiley-Liss, Inc.  相似文献   

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