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  

赵维谦 《海洋与湖沼》1994,25(5):499-504

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   

赣南地区寒武纪高滩组碎屑锆石U-Pb年龄和Hf同位素特征及地质意义     

马虎超  徐文坦  钟康惠  龚安州  郭坤一  杨川 《新疆地质》2019,(2):270-277

寒武纪高滩组广泛分布于赣南武功山-雩山地区,主体为一套浅变质砂岩夹板岩的复理石建造。为分析其物源,并对源区地壳生长和构造演化提供约束,本文对采自高滩组的变长石石英杂砂岩进行了LA-ICP-MS碎屑锆石U-Pb年代学和Hf同位素研究。锆石U-Pb年龄数据显示2 500 Ma、1 100~900 Ma和900~700 Ma 3个主要年龄峰值。2 500 Ma的年龄峰值代表了新太古代末期—古元古代的古陆核生长事件。1 100~900 Ma和900~700 Ma两个峰最显著,表明Rodinia超大陆聚合裂解在华南地区的响应,为该区寒武纪地层提供了主要物源。此外,3 003 Ma锆石年龄的捕获说明,华夏地块可能存在太古宙地壳基底。Hf同位素数据表明,源区锆石结晶多为古老地壳组分部分熔融产生的岩浆。结合锆石年龄数据分析认为,华南地区存在强烈的新元古代岩浆活动,该时期岩浆活动主要是古老地壳物质的再循环。  相似文献   

Green growth machines? Competing discourses of urban development in Playa Vista,California     

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   

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  

池再香  张锦  肖钧  吴丹  龚雪芹  李贵琼 《气象科学》2018,38(2):258-263

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   

溶解动力学和结晶动力学研究的参数优化          下载免费PDF全文

李勇  夏树屏  李青风  高世扬 《盐湖研究》1999,7(1):47-54

溶解动力学和结晶动力学研究的参数优化对研究物质的溶解、结晶转化机理和热力学行为具有重要的意义。我们将Ｒｕｎｇｅ-Ｋｕｔｔａ法与单纯形优化法相结合,针对几种适合于该法求解的微分动力学方程进行了讨论,从而为动力学研究中机理模型参数的优化提供了一种行之有效的方法。  相似文献   

裙带菜配子体对三种重金属离子毒性耐受力的研究   总被引：2，自引：0，他引：2  

侯和胜  李凝  吴超元  刘海航 《海洋与湖沼》1998,29(3):280-286

裙带菜于１９９４年采自威海市俚岛养殖场。１９９５年２月－１９９７年３月,用不同浓度（０,１,１０,１００,１０００μｍｏｌ／Ｌ）的Ｃｕ＾２＋,Ｃｄ＾２＋和Ｚｎ＾２＋处理裙带菜配子体,研究这些重金属对其生长和代谢的影响。结果表明,Ｃｕ＾２＋对裙带菜配子体生长的抑制效应最强：在１μｍｏｌ＋Ｌ时已出现抑制效应,叶绿素含量和光合作用速率明显下降,脯氨酸和丙二醛含量升高;１０μｍｏｌ／Ｌ时,配子体生长几乎停  相似文献   

Degassing and microlite crystallization during pre-climactic events of the 1991 eruption of Mt. Pinatubo, Philippines   总被引：2，自引：2，他引：0  

J. E. Hammer  K. V. Cashman  R. P. Hoblitt  S. Newman 《Bulletin of Volcanology》1999,60(5):355-380

 Dacite tephras produced by the 1991 pre-climactic eruptive sequence at Mt. Pinatubo display extreme heterogeneity in vesicularity, ranging in clast density from 700 to 2580 kg m^–3. Observations of the 13 surge-producing blasts that preceded the climactic plinian event include radar-defined estimates of column heights and seismically defined eruptive and intra-eruptive durations. A comparison of the characteristics of erupted material, including microlite textures, chemical compositions, and H₂O contents, with eruptive parameters suggests that devolatilization-induced crystallization of the magma occurred to a varying extent prior to at least nine of the explosive events. Although volatile loss progressed to the same approximate level in all of the clasts analyzed (weight percent H₂O=1.26-1.73), microlite crystallization was extremely variable (0–22%). We infer that syn-eruptive volatile exsolution from magma in the conduit and intra-eruptive separation of the gas phase was facilitated by the development of permeability within magma residing in the conduit. Correlation of maximum microlite crystallinity with repose interval duration (28–262 min) suggests that crystallization occurred primarily intra-eruptively, in response to the reduction in dissolved H₂O content that occurred during the preceding event. Detailed textural characterization, including determination of three-dimensional shapes and crystal size distributions (CSD), was conducted on a subset of clasts in order to determine rates of crystal nucleation and growth using repose interval as the time available for crystallization. Shape and size analysis suggests that crystallization proceeded in response to lessening degrees of feldspar supersaturation as repose interval durations increased. We thus propose that during repose intervals, a plug of highly viscous magma formed due to the collapse of vesicular magma that had exsolved volatiles during the previous explosive event. If plug thickness grew proportionally to the square root of time, and if magma pressurization increased during the eruptive sequence, the frequency of eruptive pulses may have been modulated by degassing of magma within the conduit. Dense clasts in surge deposits probably represent plug material entrained by each subsequent explosive event. Received: 4 December 1997 / Accepted: 13 September 1998  相似文献   

An infrared spectroscopic and single-crystal X-ray study of malayaite, CaSnSiO5     

M. Zhang  H.-W. Meyer  L. A. Groat  U. Bismayer  E. K. H. Salje  G. Adiwidjaja 《Physics and Chemistry of Minerals》1999,26(7):546-553

Powder infrared spectroscopy and X-ray diffraction techniques on single crystals were used to study the thermal behaviour of malayaite, CaSnSiO₅. Infrared spectra show a discontinuity in the temperature evolution of phonon frequencies and absorbance near 500 K. However, crystal structure data collected at 300, 450, 550, 670, and 750 K show no evidence of a symmetry-breaking phase transition and no split positions. The most obvious change with heating is a tumbling motion of the SnO₆ octahedra and an increase of the anisotropic displacement factors of Ca. The thermal evolution of the mean-square vibrational amplitude of the Ca atom shows a pronounced change in slope near 500 K. The evidence suggests that the 500 K anomaly in malayaite is more similar in character to the 825 K (β-γ) transition as opposed to the 496 K (α-β) transition in synthetic titanite. Received: 26 March 1998 / Revised, accepted: 23 December 1998  相似文献   

湖北武湖日本沼虾的生长特性   总被引：13，自引：0，他引：13  

刘军  龚世园  何绪刚  张训蒲 《湖泊科学》2003,15(2):177-183

从1998年9月至1999年9月对人工养殖湖泊——武湖日本沼虾生长特性作了研究. 以月龄来研究日本沼虾的生长,研究结果表明日本沼虾在7-1月份(1-7月龄)呈等速生长,在2-6月份(8-12月龄)呈异速生长.日本沼虾体重(W)与体长(L)呈幂函数相关,但在7-1月份时其b值接近于3,而在2-6月份时其b值明显小于3,其关系式如下: 1-7月龄:W♂=0. 0148L3. 2419(r=0. 9978,n=390),W♀=0. 0206L3. 0117(r=0. 9968,n=372); 8-12月龄:W♂=0. 0857L2. 1788(r=0.9854,n=188),W♀=0. 1450L1. 8165(r=0. 9974,n=278). 1-7月龄雄虾的生长规律符合Von Bertalanffy方程,雌虾的生长规律符合Logistic方程;8-12月龄雌雄虾的生长规律都符合Logistic方程.  相似文献   

TBT toxicity on the marine microalga Nannochloropsis oculata     

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