首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
ON THE CAUSES OF THE ZONING OF BROWN SEAWEEDS ON THE SEASHORE   总被引:1,自引:0,他引:1  
  相似文献   

3.
ON THE CAUSES OF THE ZONING OF BROWN SEAWEEDS ON THE SEASHORE   总被引:1,自引:0,他引:1  
Sarah M.  Baker 《The New phytologist》1909,8(5-6):196-202
  相似文献   

4.
5.
6.
7.
8.
9.
10.
Nd ̄(3+)对植物叶绿体类囊体蛋白复合物的影响,不仅表现在对叶绿体类囊体膜溶液的吸收光谱改变上,而且也表现在对色素蛋白复合物SDS-PAGA电泳带扫描图谱吸收峰面积变化上;同时也对DCIP光还原活力表现出抑制作用,对Ca ̄(2+)-ATPase的活力表现出低浓度激活,高浓度抑制的作用。  相似文献   

11.
12.
论山毛榉科植物的系统发育   总被引:10,自引:2,他引:8  
本文运用分支分类学方法,对山毛榉科植物进行了系统发育的分析。山毛榉科作为单元发生群包括柯属、锥属、粟属、三棱栎属、水青冈属和栎属。桦木科和南山毛榉属被选择作为外类群。对大量的性状进行评估之后,选择了25对性状作为建立数据矩阵的基本资料。性状极化以外类群比较为主,同时也采用了化石证据和通行的形态演化的基本原则。数据矩阵由7个分类群、2个外类群和25个性状组成。采用最大同步法、演化极端结合法和综合分析法对该数据矩阵进行了分析。在得到的3个树状分支图中按照最简约的原则,选出演化长度最短的谱系分支图作为本文讨论山毛榉科属间的系统演化关系的基础。关于山毛榉科植物的系统发育,作者的观点如下:(A)现存的山毛榉科的6个属形成了4条平行进化的分支路线,它们分别被处理作4个亚科,即:栗亚科,三棱栎亚科,水青冈亚科和栎亚科;(B)平行进化是山毛榉科植物系统发育过程中的主要形式。生殖过程中的一些特征,如:果实第二年成熟,胚珠通常败育等,是影响山毛榉科植物属间基因交流的主要原因。在现存的山毛榉科植物中,柯属是最原始的类群。三棱栎属和锥属的起源也较早,而栗属、水青冈属和栎属是特化的类群。  相似文献   

13.
A NOTE ON THE EFFECT OF HANDLING ON THE RESPIRATION OF POTATOES   总被引:1,自引:1,他引:0  
John  Barker 《The New phytologist》1935,34(5):407-408
  相似文献   

14.
冷杉精油在牙膏生产上的应用研究   总被引:1,自引:0,他引:1  
以冷杉精油为香原料 ,调配出复合薄荷型和果香型牙膏香精 ,并运用常规牙膏配方及加工工艺技术 ,开发出泡沫丰富、洁齿力强、香甜爽口、清淡高雅 ,并具有杀菌、消炎等保健功能的冷杉牙膏。按照国家标准 GB8372 - 87要求 ,对冷杉牙膏的质量进行了检测 ,并与其它同类牙膏产品的抑菌作用效果进行了比较 ,结果表明 ,冷杉牙膏是一种优良的绿色保健牙膏 ,具有优良的综合性能 ,完全符合国标要求 ,在某些性能上可与其它同类产品相媲美 ,有进一步中试开发的必要和广阔的应用前景。  相似文献   

15.
关于石片台面的分类   总被引:11,自引:8,他引:3  
本文分析了中国旧石器时代常见的石片台面的主要类型,提出两种世人不太注意的类型:有疤台面和刃状台面。  相似文献   

16.
《Chronobiology international》2013,30(8):1652-1667
Appreciation of chronotherapy in hypertension continues to lag, despite clear demonstrations by many studies of (i) clinically relevant dosing-time differences of the beneficial and adverse effects of most blood pressure (BP) medications and (ii) significant association between reduced sleep-time BP decline of non-dippers and their heightened risk of cardiovascular disease (CVD). The Syst-Eur and HOPE outcome trials showed evening administration of nitrendipine and ramipril in these respective studies impacts sleep-time BP, converting the 24-h BP pattern to a more dipper one and in the HOPE study decreasing CVD risk. The CONVINCE study intended to compare BP control and CVD protection afforded by conventional β-blocker and diuretic medications versus a special drug-delivery verapamil formulation as a bedtime hypertension chronotherapy; however, the trial was terminated prematurely, not based on inadequate performance of the chronotherapy but on a corporate business decision. The just completed MAPEC study is the first trial specifically designed to prospectively test the hypothesis that bedtime administration of ≥1 conventional medications exerts better BP control and CVD risk reduction than the traditional approach of scheduling all medications in the morning. The results of this 5.6-yr median follow-up study establish that bedtime chronotherapy more effectively improves BP control, better decreases prevalence of non-dipping, and, most importantly, best reduces CVD morbidity and mortality. This chronotherapeutic approach to hypertension is justified by the fact that BP is usually lowest at night as is sodium excretion, but when sodium intake is excessive or its daytime excretion hampered, nocturnal BP is adjusted higher, to a level required for compensation overnight, via the pressure/natriuresis mechanism, resulting in non-dipping 24-h BP patterning. In diurnally active persons, the entire circadian BP pattern may be reset to a lower mean level and to a “more normal” day-night variation, simply by enhancing natriuresis during the night—the time-of-day when it can be most effective. A modification as simple and inexpensive as switching ≥1 hypertension medications from morning to evening may be all that is needed to normalize nighttime BP, exerting an effect exactly like sodium restriction. Current clinical concepts such as “normotensive non-dipper” (with higher CVD risk than a hypertensive dipper), broad recommendation of pharmacotherapy with exclusively high “smoothness index” medications (without attention to individual patient needs defined by the features of the 24-h BP pattern), and reliance upon static daytime diagnostic BP thresholds based solely on single office cuff assessment necessitate urgent reconsideration. (Author correspondence: )  相似文献   

17.
18.
19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号