贝类养殖容量研究进展

近年来国内的贝类养殖产业出现大规模的病害事故,就其本质看是由于养殖区域生态环境平衡遭到破坏。本文从生态学角度出发,归纳国内外对于养殖容量概念的发展,比较各种概念的适用情况;对于养殖容量数学模型的建立和估算,介绍了目前国内外相对成熟,应用较广的模型,并且评价各种模型的优缺点。     

Effect of body condition score and reuse of progesterone‐releasing intravaginal devices on conception rate following timed artificial insemination in Nelore cows

This study had the aim of investigating the efficiency of timed artificial insemination (TAI) through the progesterone‐releasing intravaginal device (PRID), used in new condition and for the second and third times in Nelore cows. The effects of device reuse and body condition score (BCS) on the conception rate (CR) were evaluated in 1,122 multiparous Nelore cows (mean BCS of 2.7 ± 0.4), which were randomly distributed into three groups that received new (n = 330), once (n = 439) and twice used (n = 353) PRID. Among the 1,122 females that underwent TAI, 573 became pregnant, thus representing an overall CR of 51.06%. Cows with BCS between 2.75 and 4.0 had greater (p < .0001) CR (69.75%) than cows with BSC of 2.0–2.5 (32.98%). It was observed that the CR through using PRID was 60.00%, 51.71% and 41.93% for new, once and twice used PRID, respectively, with difference between all groups (p < .0001). Under tropical conditions, animals with BCS greater than 2.5 had a higher CR, and the CR decreased proportionally with the number of times that the PRID had been used.     

Relationship of the conception rate and the side (left or right) of preovulatory follicle location at artificial insemination in dairy heifers

In this study, we examined the locational effect (left or right ovary) of the preovulatory follicle (PF) on fertility in dairy heifers. In total, 1,111 artificial inseminations (AI) were analyzed. At AI, PF locations were examined using rectal palpation, and heifers were divided into two groups on their PF locations: (i) the PF located in the left ovary (L‐PF); and (ii) the PF located in the right ovary (R‐PF). Pregnancy was diagnosed by rectal palpation 60 days after AI. The conception rate was 50.7% in all heifers. Conception rate was significantly higher in the L‐PF (60.1%) than in the R‐PF (46.2%). The conception rate was significantly lower by sexed semen (48.6%) than conventional semen (59.1%). Conception rates divided by the semen type (sexed: n = 896, conventional: n = 215) were significantly higher in the L‐PF than in the R‐PF for both semen types (sexed; L‐PF vs. R‐PF: 57.3% vs. 44.4%, conventional; L‐PF vs. R‐PF: 72.3% vs. 53.3%). In addition, season, age, AI number, and the number of re‐inseminations at the same estrus did not affect conception rates. In summary, PF development in the left ovary was associated with increased conception rates in dairy heifers.     

植物与营造花境景观意境的关系

近年来花境越来越多的被应用到了城市的各个场所,也受到人们的密切关注,在花境景观意境营造上也得到了长足的发展,但是仍会有富含景观意境和随意搭配种植2种截然相反的情况出现。针对这种情况,现结合我国现有的一些花境景观实例结合植物景观意境营造理论,探讨植物选择对于营造花境景观意境上千丝万缕的联系,并提出改进意见。     

新世纪湖南林业产业的发展道路问题(二)--林业产业主导产业的现状、发展趋势

对人造板业、木竹制浆造纸业、木竹家具地板业、林产化工业、森林食品(含油类)业和林药加工业等湖南省林业工业支柱产业的现状及发展趋势作了评述和分析，并对新世纪湖南林业产业发展的总体思路、发展重点、发展战略和政策措施进行较周密的论述。     

生态综合指数初步研究

经过综合研究分析国内外评估判断生态状况的理论和方法，提出了适合我国国情的定量化的科学评估生态状况的方法——生态综合指数，初步研究分析了其基本内涵、推出根据、指标选取、判断方法、对不同发展阶段国家的意义及我国生态综合指数的计算，对我国生态状况的判断和我国生态建设的理论和实践都具有重要的意义。     

试论高品质居住小区景观设计的基本理念和风格

通过对高品质居住小区特征与内涵的分析，提出了“以人为本”是“高品质小区”的基本设计理念以及用“小区自己的方式”来设计才能真正体现高品质小区的设计风格的观点。以此构建集人性化、体闲化、个性化等特征于一体的生态环保小区、文化小区。     

农业科技成果转化存在的问题分析(Ⅱ)

在以往研究中国农业科技成果转化现状的基础上,研究了制约农业科技成果推广的因素。就农民方面来讲主要为:农民对科技成果的转化吸纳程度;利益机制因素;农业的风险性和不确定性因素;技术市场的不完善因素;农民的经营理念方面的因素以及农民的文化素质偏低等因素。以便采取相应的对策措施。     

网师园的空间景观与环境行为探究

从网师园的历史沿革、造园立意、平面布局、主要景观及空间特色等方面分析了园内环境景观与古代文人雅士的居、息、游、赏,以及现代游览者领略文化、休闲游园等行为活动之间的关系。探究了“因诗成景”、“以画入园”的独特景观营造思想和布局手法及其在有限空间的无限意境中提高人们感知、体验、参与环境的行为价值。最后结合当下的时代精神,提炼了中国古典园林中的景观环境行为理念。     

遗址公园景观设计中意境的营造探析——以扬州唐城遗址公园为例

在解析意境含义的基础上,总结了园林意境的表达方式,进而以扬州唐城遗址公园为例,探究了遗址公园景观设计中意境的营造,详细分析了唐城遗址公园的营造主题、借景手法、布局方式、景观小品设计、色彩选取、主题活动等内容。