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991.
为在PrinceRupert林区的“亚北方”部分建立生态立地质量与森林生产力的联系,对从93个小杆松林分和77个白云杉林分获得的数据进行了分析.所研究的林分处于两个气候状况、8个土壤水分状况以及5个土壤养分状况.这些气候、土壤水分和养分状况被视为等级变量用于林地分类和回归分析.小杆松和白云杉的立地指数随土壤水分和养分状况变化而变化,但不依赖于气候变化.与土壤水分相关的变化格局对两个种来说很相似,但与土壤养分相关的变化格局则全然不同.在所建立的5类回归模型中,土壤小区模型对于两个种都显示出立地指数与土壤水分和养分状况具有很强的相互关系(R2>0.80,SEE≤1.6m).可以认为土壤水分和养分的等级度量在大范围内可作为小杆松和白云杉立地指数的预测预报因子. 相似文献
992.
Tillering responses to light quality in different phenological stages of a perennial warm-season grass Eragrostis curvula were investigated in controlled environments. In vegetative plants, the tillering rate was greater (P<0.01) in the high (1.1–1.3) than in the low (0.59–0.70) red:far-red ratio (R/FR) light regime. Tillering rates were higher in the low R/FR treatment when the plants in the high R/FR regime reached the reproductive stage, while the plants in the low R/FR regime remained vegetative. After the reproductive tillers were removed by defoliation, more tillers were produced in the defoliated plants grown in the high R/FR regime. When the plants in both light treatments entered the reproductive stage, the tillering rate under the two light regimes became similar, suggesting a significant interaction between tillering and inflorescence development. The more advanced inflorescence development in the high R/FR regime may have reduced assimilate availability to tiller growth and overshadowed the effect of high R/FR on tillering. Both tillering and inflorescence development appeared to be controlled by R/FR ratio. The higher rate of aerial tiller production on the reproductive culms during the post-anthesis period in the high R/FR regime suggested that high R/FR ratio stimulated not only basal tillering, but also aerial tillering. 相似文献
993.
Jie Hao Jiani Cao Lei Wang Aijin Ma Si Chen Jinfeng Ding Liu Wang Boqiang Fu Yu Zhang Xuetao Pei Peng Xiang Qiyuan Li Yong Zhang Jiaxi Zhou Shijun Hu Junying Yu Jun Wei Huanxin Zhu Glyn Stacey Tongbiao Zhao Qi Zhou 《Cell proliferation》2020,53(12)
‘Requirements for Human Embryonic Stem Cells’ is the first set of guidelines on human embryonic stem cells in China, jointly drafted and agreed upon by experts from the Chinese Society for Stem Cell Research. This standard specifies the technical requirements, test methods, test regulations, instructions for use, labelling requirements, packaging requirements, storage requirements and transportation requirements for human embryonic stem cells, which is applicable to the quality control for human embryonic stem cells. It was originally released by the China Society for Cell Biology on 26 February 2019 and was further revised on 30 April 2020. We hope that publication of these guidelines will promote institutional establishment, acceptance and execution of proper protocols, and accelerate the international standardization of human embryonic stem cells for applications. 相似文献
994.
995.
对美国 FDA 于 2014 年 11 月 18 日发布的政策与程序手册“对基于问题审评的申报资料的药学审评”进行介绍与讨论,包括发
布该手册的目的、背景、采用基于问题的药学审评的优势、相关政策、各自职责与程序等,以及原文附件中与原料药及制剂申报相关的
技术问题,以便于药学工作者了解与药学审评相关的问题的全貌。 相似文献
996.
Abstract. 1. Cricket model systems have greatly enhanced our knowledge about mate choice and sexual selection. However, no studies exist that take seasonal dynamics into account and that follow individual males over the complete adult stage in the wild. In the present study, all adult field crickets ( Gryllus campestris L.) were individually marked and measured in a population in central Germany and their behaviour was followed over their life from May to July 2000.
2. The population reached a maximum of 108 males within 10 days and continuously declined thereafter. Daily mortality was positively correlated with burrow-changing activity, which was highest at high mean temperatures. Median burrow occupation time was short at 1 day but males stayed up to 34 days in one burrow. Heavy males stayed longer in burrows and achieved a higher age.
3. Male displacement was on average 2.8 m per day and up to 284 m during their life. Displacement and lifespan were negatively correlated.
4. Burrows were highly aggregated at the meadow in areas of vegetation cover <85%. Aggregation of males increased with advancing season and declining population size. Consequently, nearest-neighbour distances remained stable at 5 m until the 50th day of the study.
5. About half of the 159 detected matings occurred 4–6 h after sunrise. An increased mating frequency was observed between the 30th and 50th day after adult moult. 相似文献
2. The population reached a maximum of 108 males within 10 days and continuously declined thereafter. Daily mortality was positively correlated with burrow-changing activity, which was highest at high mean temperatures. Median burrow occupation time was short at 1 day but males stayed up to 34 days in one burrow. Heavy males stayed longer in burrows and achieved a higher age.
3. Male displacement was on average 2.8 m per day and up to 284 m during their life. Displacement and lifespan were negatively correlated.
4. Burrows were highly aggregated at the meadow in areas of vegetation cover <85%. Aggregation of males increased with advancing season and declining population size. Consequently, nearest-neighbour distances remained stable at 5 m until the 50th day of the study.
5. About half of the 159 detected matings occurred 4–6 h after sunrise. An increased mating frequency was observed between the 30th and 50th day after adult moult. 相似文献
997.
998.
Human activities have inflicted profound damage upon many ecosystems, and ecologists are now seeking effective means of restoring ecosystems to their natural state. Industrial ports and harbors are highly modified and often depauperate in native fauna. They are typically characterized by poor water quality and modified community composition, both of which may hinder attempts to reintroduce native species. Here, we conducted a field experiment to separate the effects of the recipient environment and community composition on the success of endemic sponge explants in Port Kembla Harbor, NSW, Australia. A reciprocal transplant was conducted between communities originating from six sites that varied in water quality and community composition, enabling us to assess the relative factors simultaneously. A colony of the endemic sponge Tedania anhelans was then inserted into the center of each community, and we quantified the survival, growth, and metal bioaccumulation of sponges over three months. Endemic sponges consistently performed better against resident assemblages when water quality was good. Sponges transplanted to cleaner sites had over double the survivorship and approximately three times the surface area of sponges transplanted to disturbed sites. These patterns were independent of community composition. Bioaccumulation of metals in sponges was correlated with survival; however, other factors such as turbidity may be required to explain sponge mortality at some sites. This study adds to evidence that remediation of the physical and chemical environments may be a prerequisite for biological remediation and demonstrates the value of experimental transplants in assessing restoration potential. 相似文献
999.
Abstract. 1. Although predatory insects often feed on diverse prey, their reproductive activity may be linked most strongly to a more restricted range of prey. The propensity of adult females of the ladybird beetle, Coccinella septempunctata L., to attack two natural prey species, pea aphids [ Acyrthosiphon pisum (Harris)] and alfalfa weevil larvae [ Hypera postica (Gyllenhal)], was compared, and the degree to which ladybird egg production depends on consumption of aphids vs. weevils was assessed.
2. Coccinella septempunctata females more readily attacked aphids than weevil larvae. This was true regardless of whether females had fed previously on aphids or on weevil larvae.
3. When females were provided with few to many aphids daily, or few aphids plus an excess number of weevil larvae, their rates of egg production depended primarily on the number of aphids consumed.
4. Addition of weevil larvae to diets of limited numbers of aphids increased egg production, but only modestly. Thus, consumption of weevil larvae may have served mostly for self-maintenance, thereby enabling females to use for egg production more of the nutrients and energy obtained from limited consumption of aphids.
5. The females' linkage of egg production primarily to aphid rather than weevil consumption may be adaptive, as their offspring are much less able as larvae to survive and mature on a diet of weevils rather than aphids. 相似文献
2. Coccinella septempunctata females more readily attacked aphids than weevil larvae. This was true regardless of whether females had fed previously on aphids or on weevil larvae.
3. When females were provided with few to many aphids daily, or few aphids plus an excess number of weevil larvae, their rates of egg production depended primarily on the number of aphids consumed.
4. Addition of weevil larvae to diets of limited numbers of aphids increased egg production, but only modestly. Thus, consumption of weevil larvae may have served mostly for self-maintenance, thereby enabling females to use for egg production more of the nutrients and energy obtained from limited consumption of aphids.
5. The females' linkage of egg production primarily to aphid rather than weevil consumption may be adaptive, as their offspring are much less able as larvae to survive and mature on a diet of weevils rather than aphids. 相似文献
1000.
ABSTRACT In order to find out the relationship between the leaf quality of R. obtusifolius and the ecology of G. viridula , a series of experiments was carried out. The effects of leaf age on rates of growth of instars of G. viridula showed that the leaf age was closely related to the development of the larvae of G. viridula . Also, the results showed quite clearly that the N concentration of R. obtusifolius leaves have significant effects on the growth rates of G. viridula larvae. It is suggested that C: N ratio of food plant plays an important role in the population dynamics of phytophagous insects. A small increase in leaf N concentration in a nutrient poor habitat will substantially increase the G. viridula population. 相似文献