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   3184篇
  免费   164篇
  2023年   21篇
  2021年   12篇
  2020年   52篇
  2019年   83篇
  2018年   108篇
  2017年   143篇
  2016年   119篇
  2015年   99篇
  2014年   88篇
  2013年   970篇
  2012年   78篇
  2011年   72篇
  2010年   109篇
  2009年   98篇
  2008年   81篇
  2007年   67篇
  2006年   69篇
  2005年   51篇
  2004年   53篇
  2003年   59篇
  2002年   56篇
  2001年   54篇
  2000年   47篇
  1999年   40篇
  1998年   38篇
  1997年   47篇
  1996年   26篇
  1995年   28篇
  1994年   29篇
  1993年   29篇
  1992年   29篇
  1991年   27篇
  1990年   23篇
  1989年   12篇
  1988年   27篇
  1987年   19篇
  1986年   17篇
  1985年   36篇
  1984年   27篇
  1983年   38篇
  1982年   27篇
  1981年   28篇
  1980年   19篇
  1979年   27篇
  1978年   25篇
  1977年   19篇
  1976年   23篇
  1975年   16篇
  1974年   21篇
  1972年   9篇
排序方式: 共有3348条查询结果,搜索用时 22 毫秒
101.
ABSTRACT

Soon after its formation, the Communist Party of Great Britain (CPGB) was tasked by the Communist International with assisting their Irish comrades to develop their organisation. This article outlines the relations between British and Irish communists from 1920 to 1941 and argues that, notwithstanding the selfless work of some British communists, the CPGB on the whole exhibited a patronising and paternalistic demeanour towards the Irish that failed to consider the latter’s perspective on an equal footing to its own, even in their own affairs. This attitude, combined with its position within the heart of the British Empire, is indicative of ‘cultural imperialism’.  相似文献   
102.
103.
104.
105.
Telepresence-enabled exploration of deep sea environments has developed over the past 30 years, providing access to archaeologists, scientists, and the general public to sites otherwise inaccessible due to depth. Pioneered through the inception of the JASON Project in the late 1980 s, telepresence missions have expanded to two dedicated ships of exploration, NOAA Ship Okeanos Explorer and exploration vessel Nautilus, and has been implemented on a series of opportunistic missions on other vessels. This paper chronicles the history of the use of telepresence for the exploration of shipwrecks in deep water as well as how this capability has allowed the public to engage with such missions. Broadening the scope of who can explore the deep sea, telepresence has also expanded what is observed and documented in the deep, which speaks to humanity’s use of the maritime world and an archaeology of discard through our material disposed of into the deep sea.  相似文献   
106.
Haig, D.W., October 2017. Permian (Kungurian) Foraminifera from Western Australia described by Walter Parr in 1942: reassessment and additions. Alcheringa 42, 37–66. ISSN 0311-5518.

Exceptionally well-preserved siliceous agglutinated Foraminifera originally recorded by Walter Parr in 1942 are redescribed and illustrated by rendered multifocal reflected-light images. Significant new observations are made on wall texture and apertural morphology. The specimens are from the Quinnanie Shale and lower Wandagee Formation in the Merlinleigh Sub-basin of the Southern Carnarvon Basin, a marginal rift that splayed from the East Gondwana interior rift. During the Early Permian, a restricted shallow sea inundated the rift. The formations are part of sequence III of the Byro Group and belong within the Kungurian Stage (Cisuralian, Lower Permian). Of the 14 agglutinated species described by Parr, six are retained under their original names, viz., Hyperammina coleyi Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar], H. rudis Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar], Ammodiscus nitidus Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar], A. wandageeensis Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar], Tolypammina undulata Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar] and Reophax tricameratus Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar]; one is transferred to a different species, viz., Thurammina texana Cushman &; Waters, 1928a Cushman, J.A. &; Waters, J.A., 1928a. Some Foraminifera from the Pennsylvanian and Permian of Texas. Contributions from the Cushman Laboratory for Foraminiferal Research 4, 3155. [Google Scholar]; six are placed with other genera, viz., Thuramminoides pusilla (Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar]), Teichertina teicherti (Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar]), Sansabaina acicula (Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar]), Tolypammina? adhaerens (Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar]), Kunklerina subasper (Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar]), Trochamminopsis subobtusa (Parr, 1942 Parr, W.J., 1942. Foraminifera and a tubicolous worm from the Permian of the North-West Division of Western Australia. Journal of the Royal Society of Western Australia 27, 97115. [Google Scholar]); and a species of Ammobaculites Cushman, 1910 Cushman, J.A., 1910. A monograph of the Foraminifera of the North Pacific Ocean. Part 1. Astrorhizidae and Lituolidae. United States National Museum, Bulletin 71(1), 134 pp. [Google Scholar] identified by Parr is now left in open nomenclature. From Parr's material, eight additional species are described: two new species, viz., Hyperammina parri sp. nov. and Gaudryinopsis raggatti sp. nov.; rare representatives of Aaptotoichus quinnaniensis Haig, 2003 Haig, D.W., 2003. Palaeobathymetric zonation of foraminifera from lower Permian shale deposits of a high-latitude southern interior sea. Marine Micropaleontology 49, 317334. 10.1016/S0377-8398(03)00051-3[Crossref], [Web of Science ®] [Google Scholar]; and very rare species of Lagenammina Rhumbler, 1911 Rhumbler, L., 1911. Die Foraminiferen (Thalamophoren) der Plankton-Expedition, Erster Teil, Die allgemeinen Organizationsverhaltnisse der Foraminiferen. Ergebnisse der Plankton-Expedition der Humboldt-Stiftung, Kiel u. Leipzig, 3L.c. (1909), 1331. [Google Scholar], Giraliarella Crespin, 1958 Crespin, I., 1958. Permian foraminifera of Australia. Bureau Mineral Resources, Geology and Geophysics, Bulletin 48, 1207. [Google Scholar], Glomospira Rzehak, 1885 Rzehak, A., 1885. Bemerkungen über einige Foraminiferen der Oligocän Formation. Verhandlungen des Naturforschenden Vereins in Brünn 1884(23), 123129. [Google Scholar], Hormosinella Shchedrina, 1969 Shchedrina, Z.G., 1969. O nekotorykh izmeneniyakh v sisteme semeystv Astrorhizidae i Reophacidae (Foraminifera). Voprosy Mikropaleontologii 11, 157170. [Google Scholar], and Reophax Denys de Montfort, 1808 Denys de Montfort, P., 1808. Conchyliologie Systématique et Classification Méthodique des Coquilles, Volume 1. F. Schoell, Paris, 409. 10.5962/bhl.title.10571[Crossref] [Google Scholar], all of which are left in open nomenclature. Hyperammina rudis is the type species of Hyperamminita Crespin, 1958 Crespin, I., 1958. Permian foraminifera of Australia. Bureau Mineral Resources, Geology and Geophysics, Bulletin 48, 1207. [Google Scholar], a genus now considered a junior subjective synonym of Hyperammina Brady, 1878 Brady, H.B., 1878. On the reticularian and radiolarian Rhizopoda (Foraminifera and Polycystina) of the North Polar Expedition of 1875–76. Annals and Magazine of Natural History, ser. 1(6), 425440. 10.1080/00222937808682361[Taylor &; Francis Online] [Google Scholar]. Thuramminoides pusilla is considered a senior subjective synonym of T. sphaeroidalis Plummer, 1945 Plummer, H.J., 1945. Smaller Foraminifera in the Marble Falls, Smithwick, and Lower Strawn strata around the Llano Uplift in Texas. The University of Texas, Publication 4401, 209271. [Google Scholar], the type species of Thuramminoides Plummer, 1945 Plummer, H.J., 1945. Smaller Foraminifera in the Marble Falls, Smithwick, and Lower Strawn strata around the Llano Uplift in Texas. The University of Texas, Publication 4401, 209271. [Google Scholar]. Imagery is presented confirming that the simple cylindrical canals through the wall of Teichertia teicherti differ from the branching canals in Crithionina rotundata Cushman, 1910 Cushman, J.A., 1910. A monograph of the Foraminifera of the North Pacific Ocean. Part 1. Astrorhizidae and Lituolidae. United States National Museum, Bulletin 71(1), 134 pp. [Google Scholar], type species of Oryctoderma Loeblich &; Tappan, 1961 Loeblich, A.R. &; Tappan, H., 1961. Remarks on the systematics of the Sarkodina (Protozoa), renamed homonyms and new and validated genera. Proceedings of the Biological Society of Washington 74, 213234. [Google Scholar]. The collection contains some of the earliest representatives of the revised family Verneuilinoididae Suleymanov, 1973 Suleymanov, I.S., 1973. Nekotorye voprosy sistematiki semeystva Verneuilinidae Cushman 1927 v svyazi s usloviyami obitaniya. Dokladari Uzbekiston SSR. Fanlar Akademiyasining, Tashkent 1973, 3536. [Google Scholar], herein elevated from subfamily rank, and considered to include Pennsylvanian–Cisuralian representatives of Mooreinella Cushman &; Waters, 1928a Cushman, J.A. &; Waters, J.A., 1928a. Some Foraminifera from the Pennsylvanian and Permian of Texas. Contributions from the Cushman Laboratory for Foraminiferal Research 4, 3155. [Google Scholar], Aaptotoichus Loeblich &; Tappan, 1982 Loeblich, A.R. &; Tappan, H., 1982. A revision of mid-Cretaceous textularian foraminifers from Texas. Journal of Micropalaeontology 1, 5569. 10.1144/jm.1.1.55[Crossref] [Google Scholar], Digitina Crespin &; Parr, 1941 Crespin, I. &; Parr, W.J., 1941. Arenaceous Foraminifera from the Permian rocks of New South Wales. Journal and Proceedings of the Royal Society of New South Wales 74, 300311. [Google Scholar], Gaudryinopsis Podobina, 1975 Podobina, V.M., 1975. Foraminifery Verkhnego Mela i Paleogena zapadno-Sibirskoy nizmennosti, ikh znachenie dlya stratigrafii. Tomsk University Press, Tomsk, 264. [Google Scholar], Caronia Brönnimann, Whittaker &; Zaninetti, 1992 Brönnimann, P., Whittaker, J.E. &; Zaninetti, L., 1992. Brackish water foraminifera from mangrove sediments of southwestern Viti Levu, Fiji Island, Southwest Pacific. Revue de Paléobiologie 11, 1365. [Google Scholar] (=Palustrella Brönnimann, Whittaker &; Zaninetti, 1992 Brönnimann, P., Whittaker, J.E. &; Zaninetti, L., 1992. Brackish water foraminifera from mangrove sediments of southwestern Viti Levu, Fiji Island, Southwest Pacific. Revue de Paléobiologie 11, 1365. [Google Scholar]) and Verneuilinoides Loeblich &; Tappan, 1949 Loeblich, A.R. &; Tappan, H., 1949. New Kansas Lower Cretaceous Foraminifera. Journal of the Washington Academy of Sciences 39, 9092. [Google Scholar].

David W. Haig [] Centre for Energy Geoscience, School of Earth Sciences, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia.  相似文献   
107.
108.
We investigated the contribution of freshwater resources to the diet of seven Late Mesolithic hunter-gatherers (ca. 5300–7000 BC) from Northern France and Luxembourg using stable isotope ratios. In addition to the carbon and nitrogen stable isotope ratios (δ13C, δ15N), we explored the potential of the sulphur isotopic ratios (δ34S) to detect and quantify the proportion of protein derived from aquatic foodstuff. In only two sites, animal remains from an associated settlement were available and subsequently examined to decipher the isotopic differential between terrestrial and freshwater resources. The quantification of their relative contribution was simulated using a Bayesian mixing model. The measurements revealed a significant overlap in δ13C values between freshwater and terrestrial resources and a large range of δ15N values for each food category. The δ34S values of the aquatic and terrestrial animals were clearly distinct at the settlement in the Seine valley, while the results on fish from Belgium demonstrated a possible overlap in δ34S values between freshwater and terrestrial resources. Local freshwater ecosystem likely contributed to ca. 30–40 % of the protein in the diet of the individuals found in the Seine settlement. Out of this context, the isotopic signature and thus contribution of the available aquatic foods was difficult to assess. Another potential source of dietary protein is wild boar. Depending on the local context, collagen δ34S values may contribute to better assessment of the relative contribution of freshwater and terrestrial resources.  相似文献   
109.
The animal remains found at the fourteenth–fifteenth century Hof van Leugenhaeghe are crucial to reconstruct the life of the noble inhabitants, as all buildings were destroyed with the construction of a later estate on the property called the Blauwhof. The diet confirms the high social status of this nobility with the suspected consumption of pig skulls, a possible sign of wealth in late-medieval Flanders. Other signs of a noble diet are found as well: juvenile cattle, a diverse spectrum of game, partridge and grey heron. The observed pattern of a wealthy diet is consistent with the zooarchaeological assemblages found at other noble sites in late-medieval Flanders.  相似文献   
110.
Invasive vegetation species can lead to major changes in the geomorphology of coastal systems. Within temperate estuaries in the southern hemisphere, especially Australia and New Zealand, the cordgrass Spartina spp. has become established. These species are highly invasive, and their prolific growth leads to the development of supratidal environments in formerly intertidal and subtidal environments. Here, we quantified the impact of Spartina invasion on the geomorphology and sequestration capacity of carbon in the sediments of Anderson Inlet, Victoria, Australia. Spartina was first introduced to the area in the 1930s to aid in land reclamation and control coastal erosion associated with coastal development. We found that Spartina now dominates the intertidal areas of the Inlet and promotes accretion (18 mm/year) causing the formation of over 108 ha of supratidal islands over the past 100 years. These newly formed islands are calculated to potentially contain over 5.5 million tonnes of CO2 equivalent carbon. Future management of the inlet and other Spartina‐dominated environments within Australian presents a dilemma for resource managers; on the one hand, Spartina is highly invasive and can outcompete native tidal marshes, thereby warranting its eradication, but on the other hand it is likely more resilient to rising sea levels and has the potential for carbon sequestration. Whether or not the potential advantages outweigh the significant habitat change that is anticipated, any management strategies will likely require additional research into costs and benefits of all ecosystem services provided by Spartina including in relation to nutrient cycling, shoreline stabilisation, and biodiversity as well as in response to the longevity of carbon found within the sediments.  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