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51.
52.
关于鱼的生长方程的研究──Ⅱ.估计参数的一种新方法 总被引:2,自引:0,他引:2
目前描述鱼的体重生长的方程主要有(1)w=w∞[1-e^-k(t-t0)]^3,和作者对该方程推广而导出的方程(2)w=w∞[1-e^-k(t-t0)]^r,本文对基于这两个方程的4种参数估计法,指出了其不足之处,并提出了一种估计参数的新方法-搜寻逼近法。该方法比前4种方法具有更好的拟合优度,通过实例计算得到进一步的证实。此外,还外鱼的样本资料的处理作了论述。这对更好的掌握鱼的生长规律,进而合理利 相似文献
53.
Christine L. Jocoy 《Urban geography》2018,39(3):388-412
Playa Vista is a massive mixed-use development built on coastal wetlands in west Los Angeles. Its land use story illustrates how strategically constructed discourses shape contested urban spaces. Through an analysis of newspaper reporting and government documents, this paper traces how pro-Playa Vista interests changed their growth discourses rationalizing the development between 1979 and 2015. Findings suggest that pro-growth coalitions are resilient when they modify their discourses to negotiate new regulatory and political contexts, specifically pursuing sustainability fixes. They are not dogmatic in their adherence to orthodoxies of private property rights and “highest and best use” of land but rather continually reconstruct growth discourses incorporating enough of the values of their opponents (i.e. “green” values such as growth management and smart growth) that some environmental and homeowner citizens’ groups join the growth coalition, forming a “green growth machine” that not only profitably builds on the land but finances ecological restoration. 相似文献
54.
红阳猕猴桃种植基地自动站温度对其生长季的影响 总被引:2,自引:1,他引:1
利用贵州西部发耳、米箩、猴场、蟠龙、鸡场、顺场、杨梅、勺米共8个红阳猕猴桃基地2013—2015年物候期观测资料、猴场基地红阳猕猴桃果实生长期生长速率及其产量资料以及各基地2005—2015年温度资料,运用C值逼近法和决定系数(R~2)最大化法拟合红阳猕猴桃果实生长曲线,采用相关性分析方法,分析了温度对红阳猕猴桃物候期的影响。结果表明,红阳猕猴桃各个物候期出现的时间及其日数与温度变化具有一致性,但各个物候期对温度的响应表现出不一致。红阳猕猴桃开花期对平均温度、平均最高温度的响应最为明显,其相关性达到极显著水平(p0.001)。平均最高温度对果实生长期日数的影响呈负相关性,其相关性达到极显著水平(p0.005)。果实生长量的75.69%受时间影响,24.31%受气候因素影响。 相似文献
55.
56.
M. Sidharthan Kim Shin Young Lee Hoe Woul Park Kwan Soon Hyun Woung Shin 《Marine pollution bulletin》2002,45(1-12)
Commercial antifouling formulations containing TBT are the major source of organotin contamination in coastal waters. In view of the persisting TBT residues (13 ng Sn l−1) in the coastal waters of South Korea, an attempt has been made to evaluate the growth response and biochemical composition of laboratory-cultured Nannochloropsis oculata to TBT toxicity. It is evident that the persisting concentration level of TBT is high enough to cause adverse effect on the microalgal species. The EC50 (24 h) was found to be at 0.89 nM level of TBT for this marine eustigmatophyte N. oculata. Photosynthetic pigment content was significantly affected. At elevated TBT concentrations of 1.0 nM, especially pronounced changes in biochemical composition was found. TBT tolerance of N. oculata and its growth as well as biochemical responses are discussed. 相似文献
57.
增长三角作为一种新型的区域经济合作模式,自从出现就获得了迅速发展,引起了广泛关注。襄樊、十堰和南阳3市地处中部地区,通过近些年的发展已经取得了一定的经济成就,但经济水平仍显不足。同时也面临着周边武汉经济圈、中原城市群、成渝都市圈和关中城市群竞争,有被边缘化的危险。因此,襄十宛三角地区做为中部重要区域要想在未来的区域竞争中取得主动权,必须要有所作为。正是这种目的,提出了构建襄十宛增长三角的构想。 相似文献
58.
《Marine pollution bulletin》2014,78(1-2):123-131
Coastal power stations entrain large volumes of cooling water, requiring biocidal treatment to prevent biological fouling. Discharged effluent is both heated and contaminated with residual traces of biocide and so it is necessary to quantify the impacts of this discharge. Cooling water from Heysham 2 nuclear power station, NW England, UK, is discharged to the intertidal area, via a culvert (to minimise erosion and maximise dilution and dispersion by directing the effluent into the receiving water at all states of the tide) within which the effluent is contained at low water. The culvert and surrounding coastal area support a population of blue mussels (Mytilus edulis). Mussel health was determined along a gradient of exposure, using three physiological indices: Scope for Growth, Gonad Mantle Index and Somatic Condition Index (K Factor). The Mussels within the culvert exhibited reduced physiological index values compared to an external site. A trend was identified down the length of the culvert, representing a gradient of exposure and indicating a potential negative effect on growth and reproductive output. 相似文献
59.
This paper discusses the growth stages,spatial structures,quantitative fitting relationships among various parameters,growth patterns and influencing factors of mud cracks by field survey,core observation and SEM analysis.The study shows that:(1) Mud crack growth can go through three stages,i.e.the syndiagenetic stage,the burial diagenetic stage(including early diagenetic stage,middle-late diagenetic stage) and the epidiagenetic stage.(2) Quantitative fitting relationships among various parameters allow a great significance to describe the spatial structure,the regional distribution and the growth environment of mud cracks.(3) Mud crack growth has three models,such as the unilateral growth model including the linear growth pattern,the curvilinear growth pattern and the bifurcation growth pattern,the multilateral growth model including the inteisectional growth pattern,the join growth pattern and the dispersed growth pattern,and the mixed growth model including the combination of any patterns listed above.(4) Modern mud crack growth usually undergoes four stages.Sand beds in sand-mud rhythmic strata can play a lubricative role on crack growth and provide enough sandy deposits for filling cracks.(5) Mud crack growth usually produces bifurcation and bifurcation angles which are mostly 120° or 90° that are related to sediment heterogeneity and released energy.(6)Factors affecting mud crack growth cover many aspects:clay content and salinity can control the number of mud cracks in different areas;terrain can control mud crack morphology;and different sedimentary cycles can control the growth patterns and filling models of mud cracks. 相似文献
60.
The calcarean sponge Paraleucilla magna is classified as being an invasive species on the Mediterranean Sea, where it causes economic damages to mollusc farms. On the Brazilian coast, this species is considered to be cryptogenic, and information on its ecology is scarce. The same is true for Sycettusa hastifera, another calcarean sponge with a worldwide distribution. Data on the ecology of these species could help in elucidating their potential to become a threat if they are found to be exotic species in Brazil. In the present work, we studied habitat selection, growth and mortality of early juveniles of P. magna and habitat selection of S. hastifera in a Marine Reserve from Southeastern Brazil, where these species are abundant in the benthic community. Granite plates were used for habitat selection analysis, varying in substrate inclination (vertical and horizontal) and exposure to light and hydrodynamism (exposed and sheltered). To analyse the growth and mortality rates, sponges were mapped and then measured once a week for 10 weeks. If a monitored sponge was not found in the following week, it was considered to be dead. Our results showed that, although P. magna and S. hastifera are capable of inhabiting substrates exposed to different environmental conditions, they showed habitat preferences. Growth of the juveniles of P. magna seemed not to have damaged any neighbouring invertebrates. The mortality of juveniles of this species was higher during the first 2 weeks of life but its causes could not be elucidated. 相似文献