Brachiopods: biomechanical interdependences governing their origin and phylogeny

The adaptive advantage of epibenthic articulate brachiopods over inarticulate forms resulted from a modification of the mechanics of shell opening from an indirect hydraulic system to a direct muscular one. As a consequence, the articulate brachiopods were able to reduce the complex muscular system of the ancestral inarticulates, freeing two-thirds of the space within the shell for enlargement of the feeding apparatus. The original hydraulic mechanism of the inarticulate brachiopods most likely evolved from the hydrostatic skeleton of metameric lower invertebrates, probably polychaete-like annelids, as shown by a biomechanical analysis. The transitional stages between such annelids and inarticulate brachiopods are presented and explained as adaptive improvements in body construction.     

Brachiopods in mud: resolution of a dilemma

Assumptions made from studies of sparse living faunas of brachiopods, namely, that they are intolerant of mud, that the free-lying habit is confined to species without pedicles, and that the pedicle of articulate brachiopods is uniform in structure and function, do not withstand critical examination. Studies in New Zealand show that some species in the same area occur in both attached and free-lying populations. Individuals cannot always be differentiated morphologically, but the structure of populations from hard and soft substrates is distinctive. Attachment to a substrate appears to be a larval rather than an adult requirement in most species.     

水生生态系统中有竞争和捕食效应的一类简单食物网模型的稳定性分析

提出了水生生态系统中有竞争和捕食的一类简单食物网模型.首先讨论了平衡点的存在条件,利用Hurwitz判据分析了局部渐近稳定性;通过构造Lyapunov函数得到了系统全局渐近稳定的条件,并具体解释了其生物含义.从以上讨论中得到了控制3类物种存活、灭绝或共存的4个阈值.生物分析表明,水草和鱼在控制富营养化问题中起着极其重要的作用.     

水生生态系统中有竞争和捕食效应的一类简单食物网模型的稳定性分析

提出了水生生态系统中有竞争和捕食的一类简单食物网模型.首先讨论了平衡点的存在条件,利用Hurwitz判据分析了局部渐近稳定性;通过构造Lyapunov函数得到了系统全局渐近稳定的条件,并具体解释了其生物含义.从以上讨论中得到了控制3类物种存活、灭绝或共存的4个阈值.生物分析表明,水草和鱼在控制富营养化问题中起着极其重要的作用.

Abstract：

In this paper, a simple food web model with competition and predation in aquatic ecosystems is proposed.The existence conditions of equilibria are discussed and the local asymptotic stability is analyzed.By means of Lya-punov functions, the global asymptotic stability of the model is obtained.Four thresholds, which indicate the coex-istence, survival or extinction of 3 species, are obtained from the above discussions.Bio-analysis shows that aquatic weeds and fish play an important role in the control of eutrophication.     

影响玉米适口性的因素及调味剂对适口性的改善作用

文章综述了影响玉米适口性的4大因素(可溶性非淀粉多糖、植酸、霉菌毒素和物理特性)以及调味剂对适口性的改善作用。     

N,N- 二甲基甲酰胺对炔雌醚不育作用和适口性的影响

【目的】明确添加高效、安全的助剂 N,N- 二甲基甲酰胺 (N,N-Dimethylformamide,DMF) 对提高不 育剂炔雌醚（Quinestrol）药饵的不育效果,以及改善炔雌醚药饵对鼠类适口性的作用。【方法】试验设 3 个处理组, 分别投喂三组小鼠空白饵料（C 组）、炔雌醚药饵（T1 组）和 DMF- 炔雌醚药饵（T2 组）,计算饵料消耗量。 将 3 个处理组的雄、雌鼠合笼 7 d,记录雌鼠怀孕及产仔情况。高效液相色谱法检测不同配制的药饵中炔雌醚的 分布浓度。【结果】T1 和 T2 组对雄、雌鼠体重均有显著影响,且 T1 和 T2 组雄鼠肾脏器官鲜重分别低于 C 组 16.4% 和 19.7%。炔雌醚对雌性小鼠繁殖抑制作用明显,T1 和 T2 组雌鼠产仔率降低至 C 组的 37.5% 和 25.0%, 产仔数仅为 C 组的 35.0% 和 11.1%。DMF 对炔雌醚药饵适口性改善作用不明显,高效液相色谱法检测药饵中药 物的分布浓度结果表明,T2 组的糙米中炔雌醚的含量为 T1 组的 1.5 倍;DMF 提高了炔雌醚在糙米中的渗透, 从而增加了小鼠的药物摄入量。【结论】DMF 可快速有效溶解炔雌醚,并增强其在糙米中的渗透力,提高炔雌 醚药饵的抗生育作用,有望开发为具有良好应用前景的不育剂配方。     

嵊泗贻贝质量安全监测与评价

[目的]为对嵊泗贻贝食用安全进行预警提供参考。[方法]在2013~2014年6月和8月对嵊泗贻贝进行大肠杆菌数量、菌落总数、铅、镉、多氯联苯、麻痹性贝类毒素和腹泻性贝类毒素等监测。[结果]嵊泗贻贝的大肠杆菌、菌落总数、麻痹性贝类毒素、腹泻性贝类毒素符合农业部二类以上贝类生产养殖区的规定,可直接上市销售。嵊泗贻贝的铅、镉、多氯联苯符合《食品中污染物限量》(GB 2762-2012)的相关要求。[结论]嵊泗贻贝能满足使用"国家地理标志"专用标志的农产品质量要求。     

牛饲料用干玉米秸秆营养分布规律及适口性研究

为了更好推进秸秆资源开发利用,针对目前玉米秸秆作为饲料的研究现状,对干玉米秸秆的适口性和营养成分的分布规律进行了试验研究,分别测定了两种干玉米秸秆上、中、下三部分及叶片中粗蛋白,粗脂肪、粗纤维、还原糖、钙和磷的含量.结果表明:玉米秸秆果穗以上部分适口性和营养成分均好于下部秸秆,进而提出玉米秸秆用做饲料应优先选择果穗以上部分茎秆,果穗以下部分可以适当还田.为玉米收获及秸秆综合利用提供参考依据.     

中日水稻品种食味特性的研究

对天津主栽品种和日本水稻品种的食味特性进行比较表明,感官鉴定综合评价的平均值,天津品种(-0.42)低于日本品种(-0.05)。两品种群的理化特性值不存在显著差异,天津品种津稻779的直链淀粉含量、蛋白质含量以及最高粘度值都接近日本优良食味品种koshihikari和kinuhikari的水平。复回归分析结果表明,综合评价与直链淀粉含量、蛋白质含量以及最高粘度之间呈极显著相关,直链淀粉含量、蛋白质含量以及最高粘度对综合评价的贡献率为8∶7∶5。     

Competition, cooperation, and mutation: improving a synthetic replicator by light irradiation

Replication and mutation are necessary elements of evolution, and some properties of self-replicating molecules (replicators) can be explored with synthetic structures. Selection and evolution at the molecular level require systems capable of competition and inheritable change. These phenomena have now been observed with synthetic molecules. Two such molecules were prepared having sufficient structural similarity that they catalyzed each other's formation as well as their own. One of the replicators bears a photochemically active function that is cleaved on irradiation. The resulting species is more effective at replication than the original and rapidly takes over the system's resources.     

中日泰优质稻米的外观及食味差异性研究

选用中国、日本和泰国有代表性的6个主栽水稻品种,对其稻米外观、食味特性值和品尝评价值进行了分析,结果显示:3个国家的稻米品种间在外观、蛋白质含量、直链淀粉含量和淀粉糊化特性方面均存在显著差异;蛋白质含量和淀粉糊化特性值间不存在显著的相关关系,而直链淀粉含量和最高粘度、最低粘度以及最终粘度间呈现出显著负相关,但与崩解值以及消减值间的相关性并不显著;食味品尝评价方面,中、日、泰3国稻米除硬度外,米饭的外观、香气、味道、粘度和综合评价值均存在显著差异。日本"越光"稻米品质综合评价为最优,中国"稻花香"、"隆粳香1号"和"津川1号"稻米品质其次,而中国"津原45"及泰国"Hom Mali105"稻米品质处于第三档次。对中日泰代表性稻米品质的综合评价为水稻品质育种及稻米加工产业的发展提供了有益参考。     

两种不育剂药饵对黄毛鼠的适口性比较

鼠药的适口性是决定鼠害控制效果的关键因素之一。采用单只饲喂法,以稻谷为基饵,分别测定了0.005%炔雌醚和米非司酮药饵对黄毛鼠的适口性。结果表明,黄毛鼠对炔雌醚药饵平均摄食系数显著低于米非司酮;雌雄鼠对炔雌醚和米非司酮药饵的摄食差异显著。炔雌醚显著降低了雌雄鼠对药饵的摄食量,且雄鼠摄食量少于雌鼠。米非司酮提高药饵对雌鼠的适口性,但不影响对雄鼠的适口性;黄毛鼠在处理时间内对药饵的摄食量存在显著变化,雌雄鼠第1 d对炔雌醚药饵和基饵摄食量无显著差异,第2、3 d对炔雌醚药饵摄食量显著少于基饵;雌鼠第1 d对米非司酮药饵和基饵摄食无显著差异,第2、3 d取食药饵显著多于基饵,雄鼠在用药第1 d即表现出对米非司酮药饵的偏好,但随后2 d对基饵和药饵摄食量差异不显著。0.005%米非司酮的稻谷对黄毛鼠具有很好的适口性,而炔雌醚药饵配制有待改善,如增加香味剂、甜味剂等提高其适口性。     

Predation through geological time: evidence from gastropod shell repair

Warm-water marine gastropods from soft-bottom habitats show an increase in the incidence of breakage-resistant shell characteristics over geological time. The hypothesis that breakage became a more important component of selection in the middle of the Mesozoic Era is supported by the finding that frequencies of breakage-induced shell repair increased from the Pennsylvanian and Triassic periods to the Cretaceous, Miocene, and Recent.     

Predation in the paleozoic: gastropod-like drillholes in devonian brachiopods

Middle Devonian articulate brachiopods (Ludlowville and Moscow Formations, Hamilton Group, New York) have external tapered holes with a central boss that are indistinguishable from drillholes of naticid gastropods that are known from the Triassic and later. Drillholes are specific to prey (ribbed shells were avoided) and specific to sites on prey. Healed drillholes suggest penetration of live prey. As many as 44 percent of the preferred prey are drilled, indicating a level of predation that has been reported only from post-Paleozoic strata.     

剑毛帕厉螨与黔下盾螨种间相残的研究

【目的】研究食用菌害虫2种天敌剑毛帕厉螨(Stratiolaelaps scimitus)和黔下盾螨(Hyposipis chianensis)的种间相残特性,为开展两者的协调应用提供理论依据。【方法】在有或无自然猎物(腐食酪螨Tyrophagus putrescentiae)条件下,观察2种捕食螨不同螨态间的相残程度及相残后若螨的发育和雌成螨的产卵量。【结果】有自然猎物腐食酪螨时,2种螨较少发生相残。无自然猎物时,2种螨发生相残,相残程度与捕食者螨态和猎物螨态密切相关,但黔下盾螨若螨不捕食剑毛帕厉螨幼螨。捕食黔下盾螨卵或幼螨的剑毛帕厉螨若螨80%和100%发育到成螨,若螨期分别为7.88d和7.30d;捕食剑毛帕厉螨卵的黔下盾螨若螨仅有30%发育至成螨;缺乏自然猎物时,2种捕食螨相残后雌成螨的产卵量均显著低于存在腐食酪螨时的产卵量,一种捕食螨仅通过捕食另一种捕食螨,无法维持种群正常增长速度。【结论】剑毛帕厉螨与黔下盾螨不适合作为相互的猎物,存在其它更为适合的猎物时,不优先选择相残,在害虫密度较大的条件下可以同时应用。     

管理者过度自信、市场竞争与商业信用

革命历史剧是一种独特的大众文化现象，是集体记忆的影像载体。革命历史剧的流行是现实社会语境下官方意志和民众心态的不谋而合。在当下社会大众传播语境中，革命历史剧从叙事框架、人物塑造和细节描摹的三个层面进行流行式的文本创新，迎合观众对不同时空历史情境的参与渴求，从而凝聚共识，达成集体认同，完成主流意识形态的传播。     

Predation risk affects reproductive physiology and demography of elk

Elk (Cervus elaphus) in the Greater Yellowstone Ecosystem alter patterns of aggregation, habitat selection, vigilance, and foraging in the presence of wolves (Canis lupus). Antipredator behaviors like these can reduce predation risk but are also likely to carry costs. Data from five elk populations studied for 16 site years showed that progesterone concentrations (from 1489 fecal samples) declined with the ratio of elk to wolves. In turn, progesterone concentrations were a good predictor of calf recruitment in the subsequent year. Together, these data suggest that wolves indirectly affect the reproductive physiology and the demography of elk through the costs of antipredator behavior.     

硅钾镁施用水平及配比对水稻蒸煮食味品质的影响

采用随机区组设计,以垦鉴稻10号为试验材料,研究硅钾镁配比对水稻蒸煮食味品质的影响。结果表明：硅钾镁配比对稻米糊化温度和直链淀粉含量影响均未达显著水平,RVA特征值变化不一。最高黏度、热浆黏度和冷胶黏度随施硅、钾量呈先上升后下降的趋势,崩解值随施钾量的变化相反;淀粉RVA特征值随镁施用量的增加先增大后减小。处理5（每公顷施SiO2、K2O、MgO分别为4、1.84和1.3kg,下文施用水平表述方法同此）、8（施用水平依次为4、3.68和0kg）和9（施用水平依次为4、3.68和0.65kg）的Mg/K最大,为0.61。施镁量和Mg/K、RVA特征值相关不显著;钾含量与崩解值相关系数为-0.76,呈显著负相关。处理9（施用水平依次为4、3.68和0.65kg）的光泽、味道最好,综合评分最高,比其它处理高出1.3～5个百分点;精米中镁、钾含量和Mg/K与食味的各项指标相关不显著。     

数字化竞争、媒介环境与报媒融合路径

报媒是互联网时代媒体的最大输家,其传统经营模式面临彻底崩溃危机。基于PEST分析模型,采用最新数据对报媒组织外部环境进行研究,探讨政治、法律环境、经济环境、社会文化环境和技术环境的变化如何改变报业的生存环境。在此基础上,以《华尔街日报》为例,详细分析其数字化生存路径：品牌内容的延伸和整合、推出多样化视频服务、数字平台建设及多元化营销战略。最后,文章提出国内报媒应该从树立“内容第一、数字第一、受众第一”理念、品牌融合经营以及重视平台融合等几方面应对来自互联网等新兴媒体的冲击。