首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   12546篇
  免费   161篇
  12707篇
  2020年   157篇
  2019年   222篇
  2018年   488篇
  2017年   441篇
  2016年   538篇
  2015年   235篇
  2014年   236篇
  2013年   3216篇
  2012年   318篇
  2011年   496篇
  2010年   499篇
  2009年   347篇
  2008年   327篇
  2007年   344篇
  2006年   273篇
  2005年   159篇
  2004年   149篇
  2003年   132篇
  2002年   140篇
  2001年   161篇
  2000年   138篇
  1999年   148篇
  1998年   105篇
  1997年   91篇
  1996年   109篇
  1995年   109篇
  1994年   101篇
  1993年   106篇
  1992年   97篇
  1991年   93篇
  1990年   76篇
  1989年   106篇
  1988年   90篇
  1987年   105篇
  1986年   113篇
  1985年   124篇
  1984年   106篇
  1983年   143篇
  1982年   110篇
  1981年   121篇
  1980年   117篇
  1979年   111篇
  1978年   119篇
  1977年   105篇
  1976年   117篇
  1975年   99篇
  1974年   93篇
  1973年   92篇
  1972年   91篇
  1969年   74篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
103.
Benson, R.B.J., Fitzgerald, E.M.G., Rich, T.H. & Vickers-Rich, P., 2013. Large freshwater plesiosaurian from the Cretaceous (Aptian) of Australia. Alcheringa 37, 1–6. ISSN 0311-5518

We report a large plesiosaurian tooth from the freshwater early–middle Aptian (Early Cretaceous) Eumeralla Formation of Victoria, Australia. This, combined with records of smaller plesiosaurian teeth with an alternative morphology, provides evidence for a multitaxic freshwater plesiosaurian assemblage. Dental and body size differences suggest ecological partitioning of sympatric freshwater plesiosaurians analogous to that in modern freshwater odontocete cetaceans. The evolutionarily plastic body plan of Plesiosauria may have facilitated niche differentiation and helped them to exclude ichthyosaurs from freshwater environments during the Mesozoic. However, confirmation of this hypothesis requires the discovery of more complete remains.

Roger B.J. Benson [roger.benson@earth.ox.ac.uk], Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK; Erich M.G. Fitzgerald [efitzgerald@museum.vic.gov.au], Thomas H. Rich [trich@museum.vic.gov.au], Museum Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia; Thomas H. Rich and Patricia Vickers-Rich [pat.rich@monash.edu], School of Geosciences, Monash University, Clayton, Victoria 3800, Australia. Received 30.10.2012; revised 27.1.2013; accepted 31.1.2013.  相似文献   
104.
Three members of the labyrinthodont Family Capitosauridae are described. Two new species from the Arcadia Formation of the Rewan Group, Queensland, show affinities with more primitive capitosaurs and with pre-capitosaurid groups. A third skull from the Blina Shale of Western Australia is of indeterminate species. These are the first recorded capitosaurs from Queensland and Western Australia and the first Parotosuchus from a Lystrosaurus Zone fauna.  相似文献   
105.
The first known ammonite from the Maastrichtian of the Perth Basin, a single, incomplete specimen of Grossouvrites gemmatus (Huppé, 1854), is described from core material from the Lancelin No. 1 borehole. Foraminiferal and nannoplankton evidence date the ammonite as middle Maastrichtian; its age is also assessed on the basis of dinoflagellate assemblages from this section, but these give a less precise dating. The position of the ammonite with respect to a mid-Maastrichtian disconformity, which probably extended along much of the Western Australian margin is discussed.  相似文献   
106.
107.
Reviews     
ROBERT J. YOUNG. French Foreign Policy, Nineteen Eighteen to Nineteen Forty-Five: A Guide to Research and Research Materials, ed. Christoph M. Kimmich. Wilmington, Delaware: Scholarly Resources Inc., 1981. Pp. xv, 242. $17.50 (US). Reviewed by A.S. Kanya-Forstner

CHRISTOPH M. KIMMICH. German Foreign Policy, Nineteen Eighteen to Nineteen Forty Five: A Guide to Research and Research Materials. Wilmington, Delaware: Scholarly Resources Inc., 1981. Pp. ix, 293. $17.50 (US). Reviewed by Ulrich Trumpener

ALAN CASSELS. Italian Foreign Policy, Nineteen Eighteen to Nineteen Forty- Five: A Guide to Research and Research Materials, ed. Christoph M. Kimmich. Wilmington, Delaware: Scholarly Resources Inc. 1981. Pp. xi, 271. $17.50 (US). Reviewed by Peter C. Kent

VOJTECH MASTNY. Russia's Road to the Cold War: Diplomacy, Warfare, and the Politics of Communism, 1041–1945. New York: Columbia University Press, 1979. Pp. xix, 409. $16.95 (US). Reviewed by Teddy J. Uldricks

R. KEITH SCHOPPA. Chinese Elites and Political Change: Zhejiang Province in the Early Twentieth Century. Cambridge, Mass.: Harvard University Press, 1982. Pp. 280. $30.00 (US). Reviewed by J. Shrecker

EDWARD M. SPIERS. Haldane: An Army Reformer. Edinburgh: Edinburgh University Press, 1980. Pp. vi, 240. £10.00. Reviewed by John E. Kendle

IAN NISH, ed. Anglo-Japanese Alienation, 1919–1952: Papers of the Anglo-Japanese Conference on the History of the Second World War. New York: Cambridge University Press, 1982. Pp. 320. $37.50. Reviewed by Ray Jones

JOHN C. G. RÖHL and NICOIAS SOMBART, eds. Kaiser Wilhelm II: New Interpretations. Cambridge: Cambridge University Press, 1982. Pp. 319. $39.50 (US). Reviewed by Konrad H. Jarausch

ROBIN FISHER and J.M. BUMSTED, eds. An Account of a Voyage to the Northwest Coast of America in 1785 and 1786 by Alexander Walker. Vancouver: Douglas & McIntyre; Seattle: University of Washington Press, 1982. Pp. 319. $24.95. Reviewed by Christon I. Archer

ERIK P. HOFFMANN and ROBBIN F. LAIRD. The Politics of Economic Modernization in the Soviet Union. Ithaca, NY: Cornell University Press, 1982. Pp. 215. $19.50 (US). Reviewed by Cyril E. Black

WERNER G. HAHN. Postwar Soviet Politics. The Fall of Zhdanov and the Defeat of Moderation, 1946–53. Ithaca and London: Cornell University Press, 1982. Pp. 243. $19.50 (US). Reviewed by Richard K. Debo

VICTOR ROTHWELL. Britain and the Cold War, 1941–1947. London: Jonathan Cape, 1982. Pp. 551. £16. Reviewed by Gerald Jordan

DAN P. SILVERMAN. Reconstructing Europe after the Great War. Cambridge, MA: Harvard University Press, 1982. Pp. vii, 347. $25.00 (US). Reviewed by Keith L. Nelson  相似文献   
108.
Amish women have contributed to the preservation of their sect's material culture by making distinctive quilts. Their quilts created from 1870 to 1935 epitomize the uniqueness of the Amish lifestyle and can be distinguished from the body of American patchwork quilts of the same time period. While Amish quilts may be distinguished from other quilts by the use of solid colors, dark material and unique patterns, regional differences between Amish quilts are also apparent. The quilts of the Amish communities of Lancaster County, Pennsylvania, and Holmes County, Ohio have characteristics that define them as Amish, but also as unique to each region. Pennsylvania quilts are distinguished by a square shape, central design, wide borders and intricate quilting stitches. Ohio quilts show greater use of color, repeated patterns and rectangular shapes. Major variations in Amish quilts developed between geographic areas rather than over time.  相似文献   
109.
A model is proposed for the incremental force-deformation behaviour of reinforced concrete sections and members, under generalised load or deformation histories in 3D, including cyclic loading, up to ultimate deformation. At the section level the model is of the Bounding Surface type and accounts for the coupling between the two directions of bending and between them and the axial direction. For the construction of the member tangent flexibility matrix on the basis of the section tangent flexibility matrix, a piecewise-linear variation along the member is assumed for the nine terms of the tangent section flexibility matrix. Model parameters are derived on the basis of available test results for: (a) the force-deformation response under cyclic biaxial bending with normal force; (b) the hysteretic energy dissipation; (c) the secant-to-yield member stiffness, and (d) the ultimate deformation of the member under cyclic biaxial load paths.  相似文献   
110.
Smuts, Barbara Boardman. Sex and Friendship in Baboons. New York: Aldine Publishing Company, 1985. xvii + 303 pp. including appendices, bibliography, and subject index. $34.95 cloth.

Taub, David M., ed. Primate Paternalism. New York: Van Nostrand Reinhold Company, 1984. xii + 441 pp. including individual chapter references and index. $44.00 cloth.  相似文献   
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