煌斑岩能解决中温金矿床成因的争论吗？     

Nich.  MS 《东北地质科技情报》1990,(3):66-71

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物化条件倒转及其在金银富集成矿过程中的作用     

Sakh.  MS 喻文兵 《国外矿床地质》1995,(4):77-78

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A fertility transition in Sub-Saharan Africa?     

Gould WT  Brown MS 《International journal of population geography : IJPG》1996,2(1):1-22

This paper documents and summarizes data on the recent fertility decline in sub-Saharan Africa and reviews the critical theoretical, methodological, and policy issues and controversies that the African situation provokes. After an introduction, African fertility change for the period 1960-94 is described through a discussion of fertility trends and of the proximate determinants of the fertility change. This discussion is illustrated with tables on the total fertility rate for countries of sub-Saharan Africa for the periods 1975-85 and 1986-93, and total fertility rates for countries participating in the Demographic and Health Surveys (DHS) for the periods 0-3 and 4-7 years prior to the survey. Figures show maps of Africa displaying total fertility rates in sub-Saharan Africa for 1975-85 and 1986- 93, and graphs of absolute and percentage change in total fertility rates for DHS countries between periods 0-3 and 4-7 years prior to the survey. The next section deals with theoretical issues such as whether the classic model of demographic transition is applicable to Africa and Jack Caldwell's views that cultural values make Africa different. It is seen that existing theory is of limited value in explaining the recent fertility decline in the region and that the two theories are beginning to converge to some degree. Consideration of methodological issues centers on the limited usefulness of fertility data collected by the large-scale, standardized demographic surveys to aid in the identification of patterns and processes. The discussion of policy issues is concerned with how survey data have been used and interpreted to formulate policy. The paper closes by reviewing the east Asian, South African, and Caribbean models of fertility decline and discussing problems in predicting the nature and extent of future fertility change in sub-Saharan Africa in light of recent findings.  相似文献   

Infrared emission from P/Halley's dust coma during March 1986     

Hanner MS  Tokunaga AT  Golisch WF  Griep DM  Kaminski CD 《Astronomy and Astrophysics》1987,187(1-2):653-660

2 to 20 micrometers photometry of the inner dust coma of comet Halley was obtained at the NASA IRTF on Mar 6.85, 12.8, 13.75, 17.7, and 24.8. Positions offset 10" were measured as well as the central brightness. The strength of the 10 micrometers emission feature was observed to vary with location in the coma. The infrared emission is in general agreement with the dust size distribution measured from the Vega and Giotto spacecraft. Mar 6.8, 17.7, and 24.8 corresponded to strong dust jet activity. The strength of the 10 micrometers silicate emission is shown to be a sensitive indicator of grain size and thus of jet activity. Dust production rate on March 13.75, 6 h before Giotto encounter, was approximately 10(7) gm s-1.  相似文献   

The Effect of the CO32- to Ca2+ Ion activity ratio on calcite precipitation kinetics and Sr2+ partitioning     

Gebrehiwet TA  Redden GD  Fujita Y  Beig MS  Smith RW 《Geochemical transactions》2012,13(1):1

Background  

A proposed strategy for immobilizing trace metals in the subsurface is to stimulate calcium carbonate precipitation and incorporate contaminants by co-precipitation. Such an approach will require injecting chemical amendments into the subsurface to generate supersaturated conditions that promote mineral precipitation. However, the formation of reactant mixing zones will create gradients in both the saturation state and ion activity ratios (i.e., ). To better understand the effect of ion activity ratios on CaCO₃ precipitation kinetics and Sr²⁺ co-precipitation, experiments were conducted under constant composition conditions where the supersaturation state (Ω) for calcite was held constant at 9.4, but the ion activity ratio was varied between 0.0032 and 4.15.  相似文献   

Effects of BPA and DES on longchin goby (Chasmichthys dolichognathus) in vitro during the oocyte maturation     

Baek HJ  Hwang IJ  Kim KS  Lee YD  Kim HB  Yoo MS 《Marine environmental research》2007,64(1):79-86

This study was performed in order to assess whether bisphenol (BPA) and diethylstilbestrol (DES) had agonistic or antagonistic effects on oocyte maturation using marine fish. We tested the effects of these chemicals on in vitro maturation, germinal vesicle breakdown (GVBD), assay using oocytes from the longchin goby, Chasmichthys dolichognathus. During the maturation process, low concentrations of BPA and DES triggered GVBD depending on the stage of oocyte development; BPA at 0.044 nM and DES at 0.037, 0.37, and 3.73 nM induced GVBD in 0.82-0.88 mm diameter oocytes (germinal vesicle located near the center of oocytes). In 0.76-0.80 mm diameter oocytes (fully vitellogenic oocytes), BPA induced GVBD at relatively higher concentrations (4.38, 43.8, and 438 nM). In 0.86-0.90 mm diameter oocytes, BPA and DES had no observable effect on GVBD at the concentrations tested. Oocytes with diameters between 0.82 and 0.88 mm appeared to be more sensitive to these chemicals. Moreover, our results showed that BPA and DES did not inhibit GVBD.  相似文献   

有关地震区划的综合模型     

Silva  MS 张素欣 《世界地震译丛》1996,(6):7-11

引言本世纪中叶以来,随着科技、经济和社会的发展,城市已产生了引人注目的变化。人口和基础设施的增加,以及居民社会和经济条件的显著变化成为当今城市的典型特征。最近数10年地震造成的数以千计的严重伤亡事故和数以百万美元计的经  相似文献   

应用空间电磁场的解析来研究地下的电性构造     

Zhda.  MS  信永水 《物探化探译丛》1989,(6):14-21

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A survey of dioxin and furan compounds in sediments of Florida Panhandle Bay systems   总被引：1，自引：0，他引：1  

Hemming JM  Brim MS  Jarvis RB 《Marine pollution bulletin》2003,46(4):512-521

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紫苏花岗岩与宝石矿物的成因     

Rupa.  MS 田洪水 《山东地质》1991,7(1):109-116

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