山核桃果皮胡桃醌对夏季牡丹叶片光合抑制的影响

以林业废弃物山核桃果皮中提取的胡桃醌0.06mg/L喷洒牡丹叶面为处理,探讨7—8月份胡桃醌对改善夏季大田生长的牡丹叶片光合性能和减轻光合抑制的效应.结果显示:处理后的牡丹叶片与对照相比,光合速率的Pn最高值分别提高10.5%和12.8%,8月份的Pn最高值比对照推迟1h在10∶00出现,光合午休大大减轻;叶片的气孔导度变化不大、但Ci明显下降;PSⅡ光化学效率Fv/Fm降低20%和26%;ΦPSⅡ下降18.1%和19.9%;在10∶00—13∶00点光照最强阶段,叶绿素qP分别下降10%和11.6%,NPQ分别上升17.3%和14.3%.结果表明,胡桃醌减轻了夏季强光对牡丹叶片叶绿体光合机构的伤害,提高了牡丹叶片对光能的利用率.     

2013年夏季南黄海浮游植物群集

利用Utermhl方法,对2013年夏季取得的211个南黄海浮游植物样品进行鉴定分析,共鉴定出浮游植物3门60属114种(不包括未定名种),其中,硅藻42属75种,甲藻16属37种,金藻2属2种。群落组成以硅藻为主,其次是甲藻,然后是金藻。调查海区浮游植物的生态类型以温带近岸性为主,优势种为:小等刺硅鞭藻、简单裸甲藻、旋沟藻、蜂腰双壁藻、具槽帕拉藻和菱形海线藻等,小等刺硅鞭藻在本调查中作为绝对优势种出现。浮游植物细胞丰度介于0.037 0×103~32.3×103cells/L,平均值为2.04×103 cells/L;表层浮游植物细胞丰度大致从近岸到外海呈逐步降低趋势,在南黄海西部近岸的表层水体达到最高值32.3×103 cells/L,调查区东南部靠近外海区域也出现了丰度高值区。香农-威纳多样性指数在调查区北部和南部较高,而Pielou均匀度指数则在东部呈现高值区域。     

女人要警惕下半身的隐蔽大敌

专家说女人下半身最大的敌人就是妇科病。女人的下半身,最集中而又最容易出问题的部位位于腰部以下大腿之上,这块神秘的生殖三角区,被称为女人的秘密花园。女人常见妇科病归纳:女性生殖系统炎症是妇女的常见病,包括外阴炎、阴道炎、宫颈炎、输卵管炎及盆腔炎等,严重的急性盆腔炎     

小心“情绪中暑”

你知道吗？情绪也会中暑! 中暑是夏季高温天气下常见的病症,轻者表现为头晕、恶心、乏力,重者会昏迷不醒,如不及时抢救,甚至危及生命。炎热天气不仅对人体生理影响很大,对人的心理和情绪也有负面影响,这就是心理学家常说的“情绪中暑”（也称“夏季情感障碍症”）。     

祁连山地区气温和降水变化分析

利用祁连山区17个气象站1952-2007年温度和降水资料,分析了其变化特征.运用趋势线拟合及相关性分析方法,得出如下结论:(1)所有气象站的年均温和夏季均温都呈上升趋势,而年降水和夏季降水大部分是上升趋势,有少量减小.并得出年均温和夏季均温上升趋势最大的气象站,年降水和夏季降水上升趋势最大气象站,以及年降水和夏季降水下降趋势的气象站.(2)年降水与夏季降水及年均温与夏季均温都有很好的相关性,降水的相关性要好于温度的相关性.并得出相关性较好的气象站,指出气象站降水和温度的一些特点.(3)2000年以来,各气象站的年均温和年降水量变化趋势均表现出一定的差异性,并初步分析了成因.     

壳聚糖对夏季奶牛血液生化指标的影响

研究壳聚糖对夏季奶牛血液生化指标的影响.选择30头中国荷斯坦奶牛,随机分为处理组和对照组(每组各15头),进行添加剂饲喂对比试验.结果表明：添加壳聚糖后,奶牛血液的皮质醇、磷、葡萄糖显著提高(P＜0.01),甲状腺素、钾、氯、钙显著提高(P＜0.05),谷草转氨酶、肌酸激酶显著下降(P＜0.01)、pH值显著下降(P＜...     

阳泉市夏季气温变化特征分析

文章以阳泉市夏季日最高温度、日最低温度、≥35℃的高温日数、气温日较差为研究对象分析了阳泉市夏季气温的变化特征,结果表明:以上四个要素在年际间均有不同程度的上升趋势,日最高温度上升最为明显,但气温的年际变化周期并不显著。根据预测,未来年份中夏季高温日数<5天的概率最大.     

Diurnal variations of summer precipitation in Beijing

Climatic characteristics and secular trends of diurnal variations of summer precipitation in Beijing are studied using hourly self-recording rain-gauge data during 1961-2004. The results show that both rainfall amount and rainfall frequency present high values from late afternoon to early morning and reach the minima around noon. Two separate peaks can be identified in the high value period, one in the late afternoon and the other in the early morning. Taking the rainfall duration into account, it is found that the rainfall during late afternoon to midnight mainly comes from the short-duration rainfall events （an event of 1-6 hours in duration）, while the rainfall during midnight to early morning is accumulated mostly by the long-duration rainfall events （an event that lasts longer than 6 hours）. In the recent 40 years, the summer precipitation in Beijing has been considerably restructured. The total rainfall amount of short-duration events has increased significantly, while the total rainfall amount of Iong-duration events has decreased.     

水泥砼夏季施工表面早期裂缝分析与防治

本文就根据夏季施工的特点。提出一些简便易行的夏季施工早期裂缝防治措施。     

Progress in studies of the climate of humid period and the impacts of changing precession in early-mid Holocene

Studies on the climate of humid period and the impacts of changing precession in the early-mid Holocene are reviewed in this paper. High-resolution proxy data indicated that the African Humid Period, strong summer monsoon from the Arabian Sea to South Asia, northward migration of ITCZ （Intertropical Convergence Zone） over the northern South America, and the humid period of China appeared in 10.5-5.5 kaBP, 10.0--6.0 kaBP, 10.5-5.4 kaBP, and 11.0-8.0 kaBP, respectively. Modeling studies proved that summer insolation over the Northern Hemisphere increased following the changes of precession in the early Holocene, which increased the land-sea temperature contrasts, intensified the summer monsoon circulation over the area under the influence of summer monsoon. However, in the Northern Hemisphere, and finally induced a humid climate modeling results underestimated the increase of precipitation and the degree of northward extension of monsoon rain belt compared with palaeo-environmental data. These discrepancies between the modeling results and the palaeo-environmental data may be associated with the changes of North Atlantic circulation, sea ice and vegetation covers. Moreover, climate of the humid period was not stable, in which several droughts were inlaid on centennial scale. In this review, perspectives for further studies of the climate change of the humid period in the early-mid Holocene are also proposed. demy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved.