全文获取类型
收费全文 | 200篇 |
免费 | 2篇 |
出版年
2016年 | 2篇 |
2013年 | 3篇 |
2011年 | 3篇 |
2010年 | 5篇 |
2009年 | 12篇 |
2008年 | 2篇 |
2007年 | 8篇 |
2006年 | 4篇 |
2005年 | 10篇 |
2002年 | 2篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1985年 | 4篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1971年 | 6篇 |
1968年 | 3篇 |
1965年 | 2篇 |
1959年 | 2篇 |
1958年 | 3篇 |
1957年 | 3篇 |
1956年 | 3篇 |
1955年 | 4篇 |
1954年 | 2篇 |
1953年 | 2篇 |
1952年 | 4篇 |
1951年 | 5篇 |
1950年 | 2篇 |
1948年 | 2篇 |
1938年 | 1篇 |
1937年 | 2篇 |
1932年 | 1篇 |
1919年 | 1篇 |
排序方式: 共有202条查询结果,搜索用时 31 毫秒
1.
2.
LESTER R. G. CANNON 《Zoologica scripta》1987,16(4):297-303
Umagilla pacifica sp.n. and U. karlingi sp.n. are described. A revised definition of the genus Umagilla Wahl, 1909 is given and Notothrix Hickman, 1955 is reduced to a synonym of Umagilla . The nature of the hard or sclerotic structures associated with the female system, especially the bursa, of umagillids is discussed and compared to similar structures in other turbellarians. Syndesmis evelinae Marcus, 1968, S. glandulosa Hyman, 1960, S. compacta Komschlies & Vande Vusse, 1980, S. mamillata Komschlies & Vande Vusse, 1980 and s. alcalai Komschlies & Vande Vusse, 1980 are all transferred to Syndisyrinx . 相似文献
3.
R. J. C. CANNON 《Biological reviews of the Cambridge Philosophical Society》1996,71(4):561-636
4.
5.
NICOLAS RAY 《Molecular ecology resources》2005,5(1):177-180
pathmatrix is a tool used to compute matrices of effective geographical distances among samples using a least‐cost path algorithm. This program is dedicated to the study of the role of the environment on the spatial genetic structure of populations. Punctual locations (e.g. individuals) or zones encompassing sample data points (e.g. demes) are used in conjunction with a species‐specific friction map representing the cost of movement through the landscape. Matrices of effective distances can then be exported to population genetic software to test, for example, for isolation by distance. pathmatrix is an extension to the geographical information system (GIS) software arcview 3.x. 相似文献
6.
7.
K.R. GEHLSEN M.E. HADLEY N. LEVINE C.G. RAY M.J.C. HENDRIX 《Pigment cell & melanoma research》1992,5(5):219-223
Melanocyte stimulating hormone (α-MSH, α-melanotropin),Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Ly-Pro-Val-NH2, regulates melanogenesis within epidermal melanocytes of many animals. An MSH analogue ([Nle4,D-Phe7]α-MSH) that exhibits superpotency and prolonged biological activity has been synthesized, biologically characterized, and is presently in clinical trials to determine its possible clinical use in tanning of the skin. It also has potential for the diagnosis, localization, and chemotherapy of melanoma. The effects of this analogue on the growth, metastatic behavior, and invasive potential of a melanotic variant of Cloudman S-91 murine melanoma are reported here. In an intracutaneous murine model of melanoma cell tumor growth, the analogue did not increase primary tumor growth (size) after the period of administration of the peptide hormone analogue and did not affect spontaneous lung metastases. Survival times for the control and melanotropin-treated groups were similar, suggesting that overall tumor burden was not affected by treatment with the hormone analogue. Last, melanoma cell invasion through a human amniotic basement membrane in vitro was not enhanced compared to untreated cells. 相似文献
8.
9.
10.
Novel strategies for assessing and managing the risks posed by invasive alien species to global crop production and biodiversity 总被引:3,自引:0,他引:3
RICHARD BAKER RAY CANNON PAUL BARTLETT IAN BARKER 《The Annals of applied biology》2005,146(2):177-191
International actions to combat the threat posed by invasive alien species (IAS) to crops and biodiversity have intensified in recent years. The formulation of 15 guiding principles on IAS by the Convention on Biological Diversity (CBD) stimulated the International Plant Protection Convention (IPPC) to review its role in protecting biodiversity. IPPC standards now demonstrate clearly that the risks posed by any organism that is directly or indirectly injurious to cultivated or uncultivated plants can be assessed and managed under the IPPC. Since the IPPC, unlike the CBD, constitutes an international legal instrument recognised by the World Trade Organization, greater protection from the introduction of IAS is now available. However, phytosanitary measures can only be enacted if they can be justified by risk analysis and we outline some novel strategies to improve the assessment and management of the risks posed by IAS, highlighting some of the key challenges which remain. 相似文献