全文获取类型
收费全文 | 221篇 |
免费 | 14篇 |
国内免费 | 39篇 |
出版年
2022年 | 6篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 11篇 |
2012年 | 11篇 |
2011年 | 18篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 11篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2002年 | 5篇 |
2001年 | 6篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1991年 | 4篇 |
1987年 | 5篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1959年 | 3篇 |
1958年 | 4篇 |
1957年 | 5篇 |
1956年 | 2篇 |
1953年 | 2篇 |
1951年 | 3篇 |
1950年 | 2篇 |
1948年 | 2篇 |
1947年 | 4篇 |
排序方式: 共有274条查询结果,搜索用时 171 毫秒
271.
Early mouse embryos grown in tissue culture were treated with tunicamycin, an inhibitor of protein glycosylation or with αα' dipyridyl, an inhibitor of collagen secretion. Neither treatment blocked development of cleavage stage embryos nor did either interfere with blastocyst formation, hatching, or adhesion to the substratum at low concentrations. However, both treatments caused marked and specific changes in the morphology of the blastocyst outgrowth. Treatment of embryos with tunicamycin caused severe deterioration of the trophoblast layer and subsequent disintegration of the inner cell mass. Tunicamycin completely inhibited the incorporation of mannose into proteins. Treatment with αα' dipyridyl caused dose dependent retardation of the inner cell mass while the trophoblast cells were virtually unaffected. These alterations in morphogenesis occurred only in embryos treated at the blastocyst stage or later in development. Changes caused by α,α' dipyridyl could be partially reversed by addition of collagen to the culture. These findings might indicate the involvement of extracellular matrix macromolecules in embryonic organization. 相似文献
272.
Modelled effects of precipitation on ecosystem carbon and water dynamics in different climatic zones
DIETER GERTEN YIQI LUO GUERRIC Le MAIRE WILLIAM J. PARTON CINDY KEOUGH ENSHENG WENG CLAUS BEIER PHILIPPE CIAIS WOLFGANG CRAMER JEFFREY S. DUKES PAUL J. HANSON ALAN A. K. KNAPP SUNE LINDER DAN NEPSTAD LINDSEY RUSTAD ALWYN SOWERBY 《Global Change Biology》2008,14(10):2365-2379
The ongoing changes in the global climate expose the world's ecosystems not only to increasing CO2 concentrations and temperatures but also to altered precipitation (P) regimes. Using four well-established process-based ecosystem models (LPJ, DayCent, ORCHIDEE, TECO), we explored effects of potential P changes on water limitation and net primary production (NPP) in seven terrestrial ecosystems with distinctive vegetation types in different hydroclimatic zones. We found that NPP responses to P changes differed not only among sites but also within a year at a given site. The magnitudes of NPP change were basically determined by the degree of ecosystem water limitation, which was quantified here using the ratio between atmospheric transpirational demand and soil water supply. Humid sites and/or periods were least responsive to any change in P as compared with moderately humid or dry sites/periods. We also found that NPP responded more strongly to doubling or halving of P amount and a seasonal shift in P occurrence than that to altered P frequency and intensity at constant annual amounts. The findings were highly robust across the four models especially in terms of the direction of changes and largely consistent with earlier P manipulation experiments and modelling results. Overall, this study underscores the widespread importance of P as a driver of change in ecosystems, although the ultimate response of a particular site will depend on the detailed nature and seasonal timing of P change. 相似文献
273.
DAN JORGENSEN 《The Australian journal of anthropology》1983,14(1):57-65
Telefol men are reluctant to talk about conception, which they claim is ‘bad talk’. Despite this, they espouse a theory of conception, and this theory accords well with the general form of Telefol kinship. Telefol women are cognizant of the men's model, but have a further one of their own which differs from that of the men in regard to the respective contributions of the sexes and the domains in which these contributions are relevant. These domains may be glossed as kinship and cult, and this paper argues that it is the relation between these domains, as well as between women and men, that is the bone of contention. 相似文献
274.
Loss of spectral peaks in autoregressive spectral estimation 总被引:1,自引:0,他引:1