香港地区环境^14C水平研究     

梁宝鎏 M．J．Stokes仇士华  蔡莲珍 《地球化学》1995,24(C00):115-118

香港地处中国的东南端，是东南亚的发达城市，矿物燃料有大量消耗。最近广东深圳大亚湾核电站已经启动，探测和研究环境^14C水平有利于环境监测。我们采集了香港不同地区生长的一年生陆地草本植物，海洋植物和大气中的CO2进行^14C测定，并与近年来中国广西地区采集的桂皮油样品测定结果作比较。结果表明，香港地区的环境^14C水平同广西地区几乎没有差别，但都明显高于预示的平均值。目前数据作为监察基础，尚没有观察到有明显影响。  相似文献   

陆下和洋底脊橄榄岩单斜辉石中的Na.Al^IV和Al^VI：地幔中不同熔融…   总被引：1，自引：0，他引：1  

Seyler  M 马建华 《地质地球化学》1995,(1):19-24

把从大西洋洋中脊采集的无斜长石的尖晶石二辉橄缆岩和方辉橄缆岩中的单斜辉石的Ｎａ－Ａｌ＾ＩＶ和Ａｌ＾ＶＩ浓度与陆下和前大洋的无斜长石的尖晶石橄榄岩的数据进行了比较。单斜辉石的Ａｌ２Ｏ３含量在洋底橄缆岩组和陆下橄缆岩组中的同一范围内发生变化，从高铝至贫铝。然而，洋底橄缆岩中单斜辉石的Ｎａ含量（０．０２￣０．６ｗｔ％Ｎａ２Ｏ）和Ａｌ＾ＶＩ／Ａｌ＾ＩＶ比值（０．３￣１）都低于陆下橄缆岩单斜辉石的Ｎａ含量（  相似文献   

一种由磁异常畸变分析估算总磁化方向的方法     

Fedi  M 王艳君 《物探化探译丛》1995,(1):2-8

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孔内安置导向器的计算          下载免费PDF全文

A.M.库尔马舍夫 《探矿工程》1965,(2)

根据钻孔的倾角(直孔或斜孔)和导向器在钻孔中的位置,在定向钻进过程中可能有以下三种人工弯曲情况:1．向垂直钻孔中下放导向器时,通常是向安置导向器的方向偏斜。  相似文献   

金刚石钻进是提高钻探工作效率的最重要途径          下载免费PDF全文

M.И.伊赛耶夫 《探矿工程》1965,(6)

苏联国家地质委员会各机关的勘探和普查固体矿产时,钻探费用约占地质勘探总投资的20%。  相似文献   

Large-Scale Mapping Observations of the C i (3P1-3P0) and CO (J = 3-2) Lines toward the Orion A Molecular Cloud     

Ikeda M  Maezawa H  Ito T  Saito G  Sekimoto Y  Yamamoto S  Tatematsu K  Arikawa Y  Aso Y  Noguchi T  Shi SC  Miyazawa K  Saito S  Ozeki H  Fujiwara H  Ohishi M  Inatani J 《The Astrophysical journal》1999,527(1):L59-L62

Large-scale mapping observations of the 3P1-3P0 fine-structure transition of atomic carbon (C i, 492 GHz) and the J=3-2 transition of CO (346 GHz) toward the Orion A molecular cloud have been carried out with the Mount Fuji submillimeter-wave telescope. The observations cover 9 deg2 and include the Orion Nebula M42 and the L1641 dark cloud complex. The C i emission extends over almost the entire region of the Orion A cloud and is surprisingly similar to that of 13CO (J=1-0). The CO (J=3-2) emission shows a more featureless and extended distribution than C i. The C i/CO (J=3-2) integrated intensity ratio shows a spatial gradient running from the north (0.10) to the south (1.2) of the Orion A cloud, which we interpret as a consequence of the temperature gradient. On the other hand, the C i/13CO (J=1-0) intensity ratio shows no systematic gradient. We have found a good correlation between the C i and 13CO (J=1-0) intensities over the Orion A cloud. This result is discussed on the basis of photodissociation region models.  相似文献   

Reobserving the Extreme-Ultraviolet Emission from Abell 2199: In Situ Measurement of Background Distribution by Offset Pointing     

Lieu R  Bonamente M  Mittaz JP  Durret F  Dos Santos S  Kaastra JS 《The Astrophysical journal》1999,527(2):L77-L80

The EUV excess emission from the clusters A2199 and A1795 remains an unexplained astrophysical phenomenon. There has been many unsuccessful attempts to "trivialize" the findings. In this Letter, we present direct evidence proving that the most recent of such attempts, which attributes the detected signals to a background nonuniformity effect, is likewise excluded. We address the issue by a reobservation of A2199 that features a new filter orientation, usage of a more sensitive part of the detector, and, most crucially, the inclusion of a background pointing at approximately 2 degrees offset-the first in situ measurement of its kind. We first demonstrate quantitatively two facts: (1) the offset pointing provides an accurate background template for the cluster observation, while (2) data from other blank fields do not. We then performed a point-to-point subtraction of the in situ background from the cluster field, with an appropriate propagation of errors. The resulting cluster radial profile is consistent with that obtained by our original method of subtracting a flat asymptotic background. The emission now extends to a radius of 20&arcmin;; it confirms the rising prominence of EUV excess beyond approximately 5&arcmin; as previously reported.  相似文献   

Thermal Stability of Cold Clouds in Galaxy Halos     

Wardle M  Walker M 《The Astrophysical journal》1999,527(2):L109-L112

We consider the thermal properties of cold, dense clouds of molecular hydrogen and atomic helium. For cloud masses below 10-1.7 M middle dot in circle, the internal pressure is sufficient to permit the existence of particles of solid or liquid hydrogen at temperatures above the cosmic microwave background temperature. Optically thin thermal continuum emission by these particles can balance cosmic-ray heating of the cloud, leading to equilibria that are thermally stable even though the heating rate is independent of cloud temperature. For the Galaxy, the known heating rate in the disk sets a minimum mass of order 10-6 M middle dot in circle necessary for survival. Clouds of this type may in principle comprise most of the dark matter in the Galactic halo. However, we caution that the equilibria do not exist at redshifts z greater, similar1 when the temperature of the microwave background was substantially larger than its current value; therefore, the formation and the survival of such clouds to the present epoch remain open questions.  相似文献   

世界气象组织的未来     

M.F.塔哈  徐明 《气象科技》1973,(Z3)

值此国际气象组织——世界气象组织成立100周年之际,自然会引起我们回顾以往100年间所经历的事件。对此,我们怀着满意的心情来回顾这一时期整个国际气象学界所取得的显著进步。庆祝世界气象组织成立100周年,同时也是展望未来的一个极好机会。因此,本文打算就世界气象组织的未来,扼要地提出一些看法。  相似文献   

矿床的工业类型     

B.M.克列特尔  谢宗武 《地质学报》1958,37(1)

地质普查工作对世界各种矿产的储备每年都有增补。如今各种矿产和各种成因类型的矿床,其数目很可能已经有成千上万了(尚未就文献加以统计)。同时大家也都很清楚,在世界经济中起主要作用的只是某几种类型的矿床,另外还有几种类型起着辅助作用,至  相似文献