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991.
992.
This paper examines 20th-century environmental change in the subhumid southwestern Canadian Plains, specifically in relation to the dominant agricultural landscape and to the climate of the past millennium as reconstructed from proxy data. Anthropogenic landscape change in the last century has been dominated by the conversion of grasslands to ranchland and cropland. This has heightened landscape vulnerability to climatic fluctuations, especially drought. Instrumental climate records, extending back to the 1880s, highlight the variability of precipitation in this region. Proxy environmental records, derived from lake cores and tree-ring analysis, extend this picture into the last millennium and show that drought has been a recurring theme of the Prairie climate. Tree-ring records suggest that some droughts in the last millennium may have exceeded in severity any in the instrumental record. The sustainability of Prairie agriculture depends on adaptation to the amplitudes of climatic change and variability evident in these proxy records. Dans cet article nous examinons les changements environnementaux qui sont survenus pendant le 20ème siècle dans les plaines canadiennes sèches du sud-ouest, spécifiquement par rapport au paysage agricole dominant et au climat du dernier millénaire qui a été déterminéà partir de données de procuration. La transformation des prairies en ranchland et cropland est le changement du paysage le plus important dont l'homme est responsable, pour le dernier siècle. À cause de ce changement, le paysage est plus vulnérable aux fluctuations climatiques - à la sécheresse en particulier. Les enregistrements instrumentaux de climat, qui reculent jusqu'aux années 1880, mettent en évidence la variabilité des précipitations dans cette région. Les enregistrements environnementaux de procuration, dérivés d'échantillons pris dans les lacs et de la dendroanalyse, étendent cette image dans le dernier millénaire et prouvent que le thème de la sécheresse est apparu souvent dans les analyses du climat du prairie. Les enregistrements de boucles d'arbre suggèrent que, dans le dernier millénaire il y avait des sécheresses qui étaient peut-être si sévères que les instruments n'ont pas pu les enregistrer. Si l'agriculture veut survivre comme entreprise dans les prairies, il faudra qu'elle s'adapte aux amplitudes de changement et de variabilité du climat qui ont été constatées dans les données de procuration.  相似文献   
993.
An Egyptian metal vase from the Ptolemaic period was investigated metallurgically and fractographically. The metal is nearly pure silver. Despite its high purity (in archaeological terms) it is severely embrittled and cracked, mainly along grain boundaries. Factors contributing to this damage are work-hardening and residual microstructural deformation (slip and twinning), corrosion along slip lines and twin boundaries, corrosion in bauds that are the remains of coring, large equiaxed grains, externally applied forces and internal residual stresses. The metal is now friable. This must be taken into account during any further restoration of the vase: a procedure is suggested.  相似文献   
994.
995.
K. N. YU  J. M. MIAO 《Archaeometry》1998,40(2):331-339
The energy dispersive X-ray fluorescence technique was employed to study non-destructively the surface of 66 samples of Chinese porcelain, of different periods and origins, and determine the contents of 13 chemical elements, namely, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ga, Pb, Rb, Sr, Y and Zr. Principal components analysis was performed on these 13 variables, and scatter plots, incorporating the first, second and third principal components, used to study the clustering behaviour of the data. Based on these results, discriminant analysis was then performed on the data, and discriminant functions established for attributing the period and origin of the porcelains.  相似文献   
996.
To date, there has not been a sustained attempt to bring the philosophy of the Third Way into foreign policy. In order to fill this gap, the authors turn to the idea of 'good international citizenship' pioneered by the former Australian Foreign Minister, Gareth Evans. It is argued that good international citizenship provides a conceptual rationale for an ethical foreign policy as well as a standard for judging the priority accorded to the goals of security, trade and human rights. Through an examination of a number of cases, the authors conclude that Britain's record as a good international citizen has been uneven and argue—against Labour's critics—that the government has set a new course for Britain's way in the world. More importantly, it has encouraged a public debate about the meaning and priority accorded to the promotion of different values.  相似文献   
997.
Reviews     
Shicite Islam: Polity, Ideology, and Creed , Yann Richard, trans. Antonia Nevill, Oxford, U.K. and Cambridge, U.S.A.: Blackwell, 1995, pp. 217, chronology, glossary, bibliography, index.

Mongols and Mamluks: The Mamluk‐Ilkhanid War, 1260–1281 , Reuven Amitai‐Preiss, Cambridge: Cambridge University Press, 1995, xv + 272 pp.

The Bukharans: A Dynastic, Diplomatic and Commercial History 1550–1702 , Audrey Burton, Richmond, Surrey: Curzon Press, 1997, 664 pp.

Cahiers d'Asie Centrale, No. 1/2 (1996): Inde‐Asie centrale. Routes du commerce et des idées , Tashkent: l'Institut Français d'études sur l'Asie centrale/Aix‐en‐Provence: Editions Edisud, 1996, 366 pp.

The Diary of H.M. Shah of Persia during his tour through Europe in A.D. 1873 , trans. from the Persian by J.W. Redhouse, London, 1874, reprinted 1995, with a new introduction by Carole Hillenbrand, Bibliotheca Iranica. Reprint Series No. 2, Mazda Publishers, Costa Mesa, Calif., [xvi] + xi + 427 pp.

Presse und Öffentlichkeit im Nahen Osten , Christoph Herzog, Raoul Motika, and Anja Pistor‐Hatam, eds., Heidelberg: Heidelberger Orientverlag, 1995, viii + 183 pp.

The Army and the Creation of the Pahlavi State in Iran, 1910–1956 , Stephanie Cronin, London: Tauris Academic Studies, 1997, 296 pp., 3 appendices.

The Republic of Armenia, Volume III: From London to Sèvres, February‐August, 1920; Volume IV: Between Crescent and Sickle: Partition and Sovietization , Richard Hovannisian, Berkeley: University of California Press, 1996, xx + 534 pp., xii + 496 pp.

Majlis va Intikhabat: az Mashrūtah ta Payan‐i Qajar , Mansoureh Ettehadieh (Nezam‐Mafi), Tehran: Nashr‐i Tarikh‐i Iran, 1375/1996–97, 368 pp.

L'Iran au XXe siècle , Jean‐Pierre Digard, Bernard Hourcade, Yann Richard, Paris: Fayard, 1996, 459 pp.

The Shicis of Iraq , Yitzhak Nakash, Princeton: Princeton University Press, 1994, xiv + 312 pp., cloth and paperback.

Debating Religion and Politics in Iran: The Political Thought of Abdolkarim Sorush , Valla Vakili, New York, N.Y.: Studies Department, Occasional Paper Series, no. 2, The Council on Foreign Relations, Inc., 1996, 56 pp.

Tanker Wars: The Assault on Merchant Shipping during the Iran‐Iraq Conflict, 1980–1988 , Martin S. Navias and E. R. Horton, London and New York: I.B. Tauris Publishers, 1996, ix + 244 pp., including appendix, notes, index of ships, and general index. Cloth.

The Turbulent Gulf: People, Politics and Power , 2nd ed., Liesl Graz, London and New York: I.B. Tauris Publishers, 1992. 311 pp., including notes, appendices, bibliography, and index. Paperback.

The Topkapi Scroll: Geometry and Ornament in Islamic Architecture , Gülru Necipo?lu, with an essay on the geometry of the muqarnas by Mohammad al‐Asad, Santa Monica: Getty Center for the History of Art and the Humanities, 1995, xiii + 395, plates, plan, bibliography, index, $160.00.

Techniques et ressources en Iran du 7e au 19e siècle , Parviz Mohebbi, Tehran: Institut Français de Recherche en Iran, 1996.

Suppressed Persian: An Anthology of Forbidden Literature , Paul Sprachman, Costa Mesa, Calif.: Mazda Publishers, lviii + 111 pp., $29.95.  相似文献   

998.
In this paper a model of spatial Cournot competition among retail firms is devised and used to assess the effect of a variety of structural factors on retail prices and profits. The model illustrates the spatial chain of interaction that firms must anticipate to reach equilibrium when organized in chains or as independents. It shows the sensitivity of price to the location of stores, the number of stores per location, and transportation cost.  相似文献   
999.
1000.
Abstract. Since the First World War, grants of territorial autonomy have been a widespread means by which regimes of diverse ideologies and political cultures have attempted to address the demands of regional cultural communities within their borders. Cantonisation, or asymmetrical decentralisation along territorial-cultural lines, has been a common form of territorial autonomy employed by these states. Yet, despite its importance, little is known about whether and why such cantonisation measures have helped or hindered the search for peace and stability in culturally heterogeneous states. Part of the answer lies in analysing the historical-political contexts, or historical paths, by which cantonisation arrangements have emerged. Comparative analysis identifies five such paths: international settlements; state-building; democratisation or transitions from authoritarian rule; democratic maintenance; and decolonisation. Each of these paths poses distinctive problems for the evolution of the cantonisation arrangement.  相似文献   
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