全文获取类型
收费全文 | 909篇 |
免费 | 77篇 |
国内免费 | 65篇 |
出版年
2023年 | 40篇 |
2022年 | 17篇 |
2021年 | 42篇 |
2020年 | 35篇 |
2019年 | 63篇 |
2018年 | 35篇 |
2017年 | 38篇 |
2016年 | 40篇 |
2015年 | 42篇 |
2014年 | 46篇 |
2013年 | 73篇 |
2012年 | 51篇 |
2011年 | 40篇 |
2010年 | 16篇 |
2009年 | 26篇 |
2008年 | 32篇 |
2007年 | 41篇 |
2006年 | 34篇 |
2005年 | 31篇 |
2004年 | 32篇 |
2003年 | 31篇 |
2002年 | 33篇 |
2001年 | 26篇 |
2000年 | 24篇 |
1999年 | 12篇 |
1998年 | 15篇 |
1997年 | 22篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1051条查询结果,搜索用时 15 毫秒
1.
J.G. Roddick 《Phytochemistry》1974,13(1):9-25
The literature relating to chemical, biochemical and biological aspects of the steroidal glycoalkaloid, α-tomatine, is reviewed. The alkaloid, which can be used as a starting compound for the synthesis of steroidal hormones, is toxic to a wide range of living organisms. The significance of tomatine to plants which elaborate it is discussed and some possible uses of the compound are mentioned. 相似文献
2.
Elizabeth Holt 《Dialectical Anthropology》2005,29(3-4):387-396
In this paper, I read Leïla Sebbar’s staging in her novel Shérazade: 17 ans, brune, frisée, les yeux verts of the resistance by children of North African and other immigrants in the early 1980s to the French state’s cartographic modes and documents of control. The paper will consider the many uses to which the map was put by the French state in its colonization of North Africa and particularly Algeria, and later in its attempts to control the banlieues its policies of citizenship and cartographic control yielded on the margins of Paris. In this context, I will explore the ways in which the novel’s characters, living clandestinely in a squatt, simultaneously resist, put to use, and even supercede state documents of control as they disrupt everyday life and conduct heists across the city of Paris. The paper will explore unofficial cartographies of Paris, from those afforded by the radios libres and alternative publications such as Libération and Sans Frontièrez, to oral and almost proverbial networks of knowledge criss-crossing the city of Paris, while also tracing the uses to which supplemental cartographic sketches and counterfeit identity cards are put in the pages of the novel. The paper will be in dialogue with theoretical and critical formulations of space, cartography, and state control put forward by Michel de Certeau, Henri Lefebvre, Michel Foucault, and Tom Conley. The paper will conclude with a consideration of the means and limits of resistance by the novel’s characters in the context of this body of theory and criticism. 相似文献
3.
We reviewed 2524 articles published from 1987 to 1995 in five international journals, Conservation Biology , Biological Conservation , Biodiversity and Conservation , Ecological Applications , and the Journal of Applied Ecology , to assess patterns and imbalances in biodiversity research in the following subject areas: locations where research was conducted, types of organisms studied, types of ecosystems studied, types of methodologies used, and types of stresses investigated. Biodiversity research was found to be narrowly focused with little deviation from its initial course set of being a discipline concerned largely with the implications of forest habitat loss on charismatic terrestrial megafauna; i.e. the 'founder effect' is very much in evidence. The 'sleeping dragon' of ignored marine biodiversity is really symptomatic of a wider problem, and can perhaps be referred to as a 'hibernating hydra' of many imbalances due to, for example, under-representations of research from developing nations, or on amphibians and invertebrates, alpine and arctic systems, sociological components and chemical stresses etc. It is time to take steps to actively awaken the creature so that conservation biology/applied ecology can become more pluralistic in scope. 相似文献
4.
J. R. AKEROYD F.L.S. S. M. WALTERS F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1987,95(4):223-226
AKEROYD, J. R. & WALTERS, S. M. 1987. Flora Europaea: the background to the revision of Volume One. Flora Europaea, published 1964-80, is a synthetic catalogue of Europe's vascular plants. Its publication has provided a relatively stable taxonomic and nomenclatural framework for the study of the flora of the continent, and has stimulated much further research and publication. The revision of the first volume of Flora Europaea, at Reading University, has been necessary in order to accommodate new information, to satisfy the continued demand for a complete Flora of Europe, and to update the original text. The revision is being carried out in cooperation with other European and Mediterranean floristic projects. 相似文献
5.
This is a literature review of 361 opportunistic fungal infections caused by the Zygomycetes. The clinical and laboratory diagnosis, pathogenesis, management, treatment, and outcome of infection are discussed. The Zygomycetes are a group of opportunistic fungi (orders Mucorales and Entomophthorales) which cause severe infections which may be fatal. Early clinical recognition, prompt diagnostic procedures, control of underlying disease and treatment with high doses of amphotericin B and aggressive surgery increases survival in an otherwise lethal infection. 相似文献
6.
W. B. RUDMAN 《Zoological Journal of the Linnean Society》1988,93(2):133-185
The genus Ceratosoma (Nudibranchia: Chromodorididae) is reviewed and seven species, including two new species, are recognized. Species of the genus are known only from the Indo-West Pacific and it is suggested that the external body shape is the most useful character in distinguishing species. 相似文献
7.
8.
In the last few years our knowledge of the structure and function of Photosystem II in oxygen-evolving organisms has increased significantly. The biochemical isolation and characterization of essential protein components and the comparative analysis from purple photosynthetic bacteria (Deisenhofer, Epp, Miki, Huber and Michel (1984) J Mol Biol 180: 385–398) have led to a more concise picture of Photosystem II organization. Thus, it is now generally accepted that the so-called D1 and D2 intrinsic proteins bind the primary reactants and the reducing-side components. Simultaneously, the nature and reaction kinetics of the major electron transfer components have been further clarified. For example, the radicals giving rise to the different forms of EPR Signal II have recently been assigned to oxidized tyrosine residues on the D1 and D2 proteins, while the so-called Q400 component has been assigned to the ferric form of the acceptor-side iron. The primary charge-separation has been meaured to take place in about 3 ps. However, despite all recent major efforts, the location of the manganese ions and the water-oxidation mechanism still remain largely unknown. Other topics which lately have received much attention include the organization of Photosystem II in the thylakoid membrane and the role of lipids and ionic cofactors like bicarbonate, calcium and chloride. This article attempts to give an overall update in this rapidly expanding field. 相似文献
9.
腐霉属分类性状评价及其中国的种 总被引:1,自引:0,他引:1
本文对腐霉属Pythium Pringsheim的研究历史作了简单的回顾,对该属的分类性状和系统进行了论述和评价,最后对中国已发现的55种腐霉,以检索表的方式进行了分类、检索。 相似文献
10.
甘草属植物化学和药理学研究进展 总被引:2,自引:0,他引:2
本文对近年发表的有关甘草属植物化学和药理学研究文献进行了综述,其中包括了得自本属植物的新的黄酮类、三萜类成分。文中以表格形式列出了各类成分的名称、结构、物理常数和植物来源,并对某些成分的生理活性作了归纳。 相似文献