A NEW“TETRASPORANGIAL”SPECIES OF LIAGORA(RHODOPHYTA,NEMALIALES)FROM HAWAIT     

Isabella A. Abbott 《中国海洋湖沼学报》1995,(4)

A new species of Liagora,L.perennis sp.nov.from Hawai’i,is described.Unlike dpecies of this genus in China,it is carpotetrasporangial,and at the place of expected carposporangia bears cruciately di-vided tetrasporangia,a detail which differentiates it from the usual species of Liagora without tetraspores that have been reported in China.Notes are provided on other Liagora species that have an impact on the taxonomy of species found in China.  相似文献   

Identification of the interstellar cyanomethyl radical (CH2CN) in the molecular clouds TMC-1 and Sagittarius B2     

Irvine WM  Friberg P  Hjalmarson A  Ishikawa S  Kaifu N  Kawaguchi K  Madden SC  Matthews HE  Ohishi M  Saito S  Suzuki H  Thaddeus P  Turner BE  Yamamoto S  Ziurys LM 《The Astrophysical journal》1988,334(2):L107-L111

We report the astronomical identification of the cyanomethyl radical, CH2CN, the heaviest nonlinear molecular radical to be identified in interstellar clouds. The complex fine and hyperfine structures of the lowest rotational transitions at about 20.12 and 40.24 GHz are resolved in TMC-1, where the abundance appears to be about 5 x 10(-9) relative to that of H2. This is significantly greater than the observed abundance of CH3CN (methyl cyanide) in TMC-1. In Sgr B2 the hyperfine structure is blended in the higher frequency transitions at 40, 80, and 100 GHz, although the spin-rotation doubling is clearly evident. Preliminary searches in other sources indicate that the distribution of CH2CN is similar to that for such carbon chain species as HC3N or C4H.  相似文献   

The possible formation of a hydrogen coma around comets at large heliocentric distances     

Bar-Nun A  Prialnik D 《The Astrophysical journal》1988,324(1):L31-L34

An observational test--the detection of a hydrogen coma around comets at large heliocentric distances--is proposed for determining whether comets were formed by the agglomeration of unaltered, ice-coated, interstellar grains. Laboratory experiments showed that amorphous water ice traps H2, D2, and Ne below 20 K and does not release them completely until the ice is heated to 150 K. Gas/ice ratios as high as 0.63 are obtainable. Thus, if the ice-coated interstellar grains were not heated above approximately 110 K, prior to their agglomeration into cometary nuclei, the inward propagating heat waves should release from the comets a continuous flux of molecular hydrogen. This flux would exceed that of water molecules at approximately 3 AU preperihelion and approximately 4 AU postperihelion.  相似文献   

南极威尔克斯地SGR钻孔处雪冰转化过程中的密度变化特征          下载免费PDF全文

韩建康  N.W.杨 《极地研究》1988,1(1):13-24

本文着重描述了SGR钻孔处冰盖上的积雪在密实化过程中的特征变化,并对该过程进行了分段的和全面的回归分析.结果表明,冰盖密度随深度增大,但增长幅度随深度减小.作者提出密度变化减小度的概念.计算得出的所研究冰芯钻取点的密度变化减小度为-0.15kg/m~3·m~2,粒雪成冰前的密实速率平均值为4.08kg/m~3·a.本文得到的冰盖密度变化“临界点”与以往报道的有所不同.分析这一现象时,作者强调当积雪还在活动层时冰盖温度的影响,并以此解释密度剖面的异常变化以及离差的回升.特别指出,积雪的密度变化具有气候学意义,它在一定程度上能够反映出积雪形成及变化过程中气候变化的某些信息.本文由密度变化确定的钻孔点雪冰转化深度为50米.  相似文献   

Variations in the HCN/HNC abundance ratio in the Orion molecular cloud     

Goldsmith PF  Irvine WM  Hjalmarson A  Elldér J 《The Astrophysical journal》1986,310(1):383-391

We have used observations of the rare isotopes of HCN and HNC to determine the relative abundance of these two chemical isomers along the central ridge of the Orion molecular cloud. The abundance ratio [HCN]/[HNC] decreases by more than an order of magnitude from the relatively warm plateau and hot core sources toward the KL nebula to the colder, more quiescent clouds to the north and south. Even in the cooler regions, however, the ratio is an order of magnitude larger than that found in previous investigations of cold dark clouds. We determine the kinetic temperature in the regions we have studied from new observations of methylacetylene (CH3CCH), together with other recent estimates of the gas temperature near KL. The results suggest that the warmer portions of the cloud are dominated by different chemical pathways than those in the general interstellar cloud material.  相似文献   

多接收器电感耦合等离子体质谱法测定镉标准溶液中镉的同位素组成   总被引：1，自引：1，他引：0  

高博  梁细荣  刘颖  胡光黔  曾文  涂湘林 《岩矿测试》2008,27(5):321-324

建立了多接收器电感耦合等离子体质谱仪对Cd标准溶液同位素组成进行分析的实验方法。仪器的质量分馏校正采用Standard-Sample Bracketing法。实验结果用δ114/110Cd来表达。在此研究基础上,以SPEX Cd标准溶液为参考标准,对国外4种Cd标准溶液进行了测定。结果表明,实验测定的精度在0.07‰~0.13‰(δ114/110Cd),与目前文献报道的结果具有相似的精度。以最新SPEX Cd标准样品(δ114/110Cd=0)为基准,计算的δ114/110CdJMC、δ114/110CdSPEX-1、δ114/110CdBAM1012和δ114/110CdM櫣nster的值分别为0.55‰、0.56‰、-0.65‰和5.14‰,说明不同批次SPEX标准溶液的Cd同位素组成是明显不同的,最新的SPEX Cd标准溶液与SPEX-1 Cd的δ114/110Cd值存在着0.56‰的差别。将以SPEX Cd为参考标准的δ114/110CdBAM1012和δ114/110CdM櫣nster转化为以SPEX-1或JMC为参考标准后,得到的结果与文献报道的结果在误差范围内一致。  相似文献   

新疆库车新生代前陆褶皱冲断带的变形特征、时代和机制   总被引：18，自引：4，他引：14       下载免费PDF全文

李日俊  吴根耀  雷刚林  张敬洲  王月然  刘亚雷 《地质科学》2008,43(3):488-506

库车前陆褶皱冲断带自北向南可分为基底冲断带、箱状背斜带、梳状背斜带和挠曲褶皱带,东西方向上可分为西段、中段和东段。本文分段叙述了各变形带的变形特征,指出东段箱状背斜带不发育,秋里塔格山脉(构造带)东延未进入东段,因而总体看自西向东变形强度减弱,地形上趋于夷平。该冲断带的形成经历了两次重大的冲断活动,分别发生在中新世和早(-中)更新世;相应地,该带可分为南、北两个"盆""山"亚系统,两者在地层记录、变形期次和变形机制上尚有若干差异。库车前陆褶皱冲断带的发育,除了受南天山的冲断和向南扩展引起的近南北向挤压应力场控制外,还受到基底断裂在新生代的活化和膏盐层底辟的制约,前者以近北西向的构造变换带及其共轭发育的近北东向断层最为重要,后者既控制了秋里塔格山脉的形成(主要受垂直的挤压应力场作用),也在库车前陆褶皱冲断带东西方向的变形分段中起了重要作用。文章还讨论了变形与地貌发育的关系和在油气勘探中的指导意义。  相似文献   

The Nordic geological surveys： Geology for society in practice   总被引：1，自引：0，他引：1  

Morten Smelror Andreas AhlstrФm Lena Ekelund Jens Morten Hansen Keijo Nenonen Anette K. Mortensen 《《幕》》2008,31(1):193-200

Since the mid-nineteenth century., when the first of the Nordic Geological Surveys were established, they have generated a substantial amount of information on the Earth＇s crust, its natural resources, its processes, and on the geological history of Nordic areas. The collective mission of the geological surveys is to carry out ＂Geology for Society＂, by doing research and providing services, and by making geological information and data easily accessible to all the varied end users in industry, government agencies, government institutes, public administrations, technical offices, academia and research institutes, as well as for private individuals. The present paper gives a brief overview of a few, selected, research areas and projects currently undertaken by the Nordic geological surveys. These serve as practical examples of how the Nordic geological surveys address important societal problems and challenges that require geological input for their solution.  相似文献   

Geological research at the Natural History Museum of Moscow University, 1759-1930 （in Russian）     

Zoya A. Bessudnova 《《幕》》2008,31(3):368-369

In 2006, the Moscow publishing house Nauka （Science） published a 246-page book by Zoya A. Bessudnova entitled Geological Research at the Natural History. Museum of Moscow University, 1759-1930 as No. 32 in its series ＂Sketches on the History of Geological Knowledge＇. The author is a geologist and Senior Researcher in the Department for the History of Geology of the Vernadsky State Geological Museum of the Russian Academy of Sciences, and a member of the International Commission on the History of Geological Sci- ences （INHIGEO）.  相似文献   

阜新—朝阳高速公路段黄土三轴剪切特性研究     

李圃林  王常明  张立新  张浩  杨立建 《水文地质工程地质》2008,35(2):49-53

对取自阜新—朝阳高速公路段的黄土进行了14C测年、颗粒分析、湿陷及常规试验等,对比分析了其基本特性,通过三轴剪切试验,获得了不同含水量的黄土剪切孔压、固结孔压、抗剪强度及剪切变形的变化特征。分析认为,辽西黄土此类特性由黄土的物质成分和结构特征所决定。对不同含水量的黄土剪切变形曲线建立力学模型,拟合结果表明,对于脆性破坏的应变软化曲线,刘祖典模型描述的效果并不理想,而文中建议的经验模型则较为适合。  相似文献