全文获取类型
收费全文 | 5502篇 |
免费 | 213篇 |
出版年
2020年 | 76篇 |
2019年 | 85篇 |
2018年 | 119篇 |
2017年 | 143篇 |
2016年 | 144篇 |
2015年 | 111篇 |
2014年 | 79篇 |
2013年 | 1549篇 |
2012年 | 106篇 |
2011年 | 118篇 |
2010年 | 136篇 |
2009年 | 137篇 |
2008年 | 139篇 |
2007年 | 114篇 |
2006年 | 100篇 |
2005年 | 82篇 |
2004年 | 74篇 |
2003年 | 79篇 |
2002年 | 75篇 |
2001年 | 71篇 |
2000年 | 82篇 |
1999年 | 87篇 |
1998年 | 74篇 |
1997年 | 55篇 |
1996年 | 60篇 |
1995年 | 62篇 |
1994年 | 58篇 |
1993年 | 65篇 |
1992年 | 58篇 |
1991年 | 37篇 |
1990年 | 39篇 |
1989年 | 59篇 |
1988年 | 48篇 |
1987年 | 62篇 |
1986年 | 54篇 |
1985年 | 81篇 |
1984年 | 99篇 |
1983年 | 90篇 |
1982年 | 72篇 |
1981年 | 75篇 |
1980年 | 78篇 |
1979年 | 72篇 |
1978年 | 77篇 |
1977年 | 65篇 |
1976年 | 79篇 |
1975年 | 82篇 |
1974年 | 52篇 |
1973年 | 39篇 |
1972年 | 36篇 |
1971年 | 35篇 |
排序方式: 共有5715条查询结果,搜索用时 593 毫秒
981.
Catherine R. Schenk 《The Journal of imperial and commonwealth history》2013,41(2):197-220
This article examines the tense and complex monetary relationship between Britain, Singapore and Malaysia in the period from 1965 to 1972. It questions the assumption that Malaysia's economic significance to Britain was ‘on the wane’ by the 1960s. As the second largest government holder of sterling assets in the world, Malaysia should have been able to exert considerable leverage in London over the disposition of these assets. Ultimately, however, the very scale of these assets limited Malaysia's room for manoeuvre, as it could not sell off a significant proportion of them without undermining international confidence in the exchange rate of the pound and thereby precipitating the devaluation of its remaining sterling assets. The devaluation of sterling in 1967 emerges as a watershed in relations between London and Kuala Lumpur, with the Malaysians thereafter seeking to forge a more independent monetary policy. It is clear, however, that they did not actually succeed in doing so until 1972. 相似文献
982.
983.
984.
R.W. Kostal 《The Journal of imperial and commonwealth history》2013,41(1):1-34
The English East India Company has long been regarded as a ‘mere merchant’ that turned into a sovereign only with its eighteenth-century territorial acquisitions in India. Focusing on the first decades of Company rule at St Helena, this article argues instead that the late seventeenth-century Company aspired to become a polity in itself: a self-sustaining global system built upon sound civic institutions and informed by a coherent if composite political ideology. In the end, the Company's early history at St Helena demands a flexible understanding both of the boundaries of the British ‘Atlantic world’ and of the various kinds of political communities beyond the national state instrumental in fashioning early modern empires. Moreover, such a political and intellectual approach to the early Company confounds the trade-to-empire narrative that has long defined its history, insisting on deeper and more complex roots for the ‘Company-State’ and thus for British Empire in India. 相似文献
985.
The effect of charring and burial on the biochemical composition of cereal grains: investigating the integrity of archaeological plant material 总被引:1,自引:0,他引:1
A.K. Styring H. Manning R.A. Fraser M. Wallace G. Jones M. Charles T.H.E. Heaton A. Bogaard R.P. Evershed 《Journal of archaeological science》2013
Stable isotope analysis of charred archaeobotanical cereal grains has the potential to provide direct evidence of crop growing conditions in the past and to refine palaeodietary predictions. If isotope values of archaeobotanical material are to be considered robust, it is necessary to characterise the compositional changes associated with their charring and burial. This study used a suite of analytical techniques, including FT-IR and solid state 13C NMR, to characterise changes in the biochemical composition of modern einkorn grains with heating at 230 °C for 2 h, 4 h, 8 h and 24 h, encompassing conditions that replicate their undistorted ancient counterparts. The biochemical composition of archaeobotanical charred einkorn grains was also investigated by FT-IR and solid state 13C NMR in order to assess the changes in composition which occur during burial. Results of FT-IR and solid-state 13C NMR show that heating of modern einkorn grains resulted in Maillard reactions between cereal proteins and starch, forming high molecular weight melanoidins, which contain both alkyl and aromatic carbon. Loss of low molecular weight carbon and nitrogen-containing volatiles resulted in a slight but non-systematic increase in the δ13C values and a systematic increase of 0.8‰ in the δ15N values of the charred einkorn grains. Solid-state 13C NMR shows that the ancient charred einkorn grains consisted entirely of aromatic carbon and retained a similar proportion of nitrogen to their modern 24 h charred counterparts, despite a significantly lower concentration of amino acids. This indicates that the amino acid nitrogen in the ancient charred grains was retained in the stable melanoidins whose polymeric structure makes them resistant to subsequent degradation. 相似文献
986.
987.
GUANG R. SHI 《Alcheringa: An Australasian Journal of Paleontology》2013,37(1-2):103-120
Shi, Guang R., 1994:03:28. The Late Palaeozoic brachiopod genus Jakutoproductus Kashirtsev 1959 and the Jakutoproductus verchoyanicus Zone, northern Yukon Territory, Canada. Alcheringa 18, 103–120. ISBN 0311-5518. The familial and subfamilial position, species composition, and geographic distribution of the Late Palaeozoic productid genus Jakutoproductus Kashirtsev 1959 are reviewed. Jakutoproductus is placed in the subfamily Plicatiferinae Muir-Wood & Cooper 1960 of the family Plicatiferidae. Eighteen described species from the Russian Arctic. Mongolia, northeast China, and northern Yukon Territory, Canada are assigned to Jakutoproductus. The Jakutoproductus verchoyanicus Zone of late Sakmarian to Artinskian age, most likely early Artinskian (Aktastinian), here established is based on material from the Jungle Creek Formation, northern Yukon Territory, Canada, and is correlated with the following horizons in Russia: the Osennin Horizon in the Verchoyan Mountains, the lower Munugudjak Horizon of the Kolyma-Omolon Massif, the Hipkhoshin Suite of east Zabaikal, the lower Bhang Horizon of Taimyr, and an unnamed sandstone-shale unit on the north island of Novaya Zemlya. 相似文献
988.
Alex G. Cook Robert B. Blodgett R. Thomas Becker 《Alcheringa: An Australasian Journal of Paleontology》2013,37(3):181-207
Over 50 identifications of Tertiary pollen are reviewed. The pollen assemblages indicate rain-forest through most of the Tertiary, but the requisites for pollen preservation are biased towards the wetter climates. The present day geographical affinities of the botanical groups are largely with taxa of the tropical zone and Australia-wide taxa. There is geographic variation in the fossil pollen assemblages when southeastern Australia is compared with Central Australia and Queensland. The major changes in the fossil floras coincide with climatic change, indicating the influence of climate on the evolution of plant assemblages. The older phytogeographic concepts are inappropriate for the fossil record, especially when considered in conjunction with palaeoclimates and palaeogeography. It is unfortunate that palynology has given little information of the evolution of floras in drier climatic regimes, or of the evolution of the eucalypts. 相似文献
989.
Two Early Devonian gastropod genera, Garraspira gen. nov. and Anoriostoma from the GarraLimestone, with sinistrally heterostrophic shells, share several shell features and are placed in the new tribe Anoriostomatini within the subfamily Agnesiinae. In contrast to the other members of the latter subfamily these genera represent a lineage in which the apertural slit was lost during evolution. This fact supports the opinion that the presence or absence of the apertural slit does not necessarily have significance for high-level taxonomy. Morphology of the gerontic whorl in Anoriostoma sinistra and Garraspira imtsitata suggests their limited mobility during the last ontogenetic stage. 相似文献
990.
Katsumi Ueno Guang R. Shi Shu-Zhong Shen 《Alcheringa: An Australasian Journal of Paleontology》2013,37(2):257-273
Fusulinoideans from the Metadoliolina dutkevitchi-Monodiexodina sutchanica Zone of the lower part of the Chandalaz Formation in the Senkina Shapka section in South Primorye, Far East Russia, are described. The fusulinoidean zone is assigned to the early Midian (=Capitanian: late Middle Permian) based mainly on the morphologie and biostratigraphic characteristics of Metadoliolina dutkevitchi. Previously, a Midian age has been established for the Metadoliolina dutkevitchi-Monodiexodina sutchanica Zone by the coexistence of Lepidolina species. However, the occurrence of Lepidolina with the two zonal species in this area has not been verified by the illustration of Lepidolina specimens. We examined a fusulinoidean-bearing sample from the Metadoliolina dutkevitchi-Monodiexodina sutchanica Zone, and three fusulinoidean species, Monodiexodina sutchanica, Pseudofusulina sp. and Metadoliolina dutkevitchi, are de-scribed and illustrated. 相似文献