全文获取类型
收费全文 | 623篇 |
免费 | 51篇 |
出版年
2023年 | 9篇 |
2022年 | 16篇 |
2021年 | 25篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 11篇 |
2017年 | 10篇 |
2016年 | 22篇 |
2015年 | 32篇 |
2014年 | 33篇 |
2013年 | 60篇 |
2012年 | 57篇 |
2011年 | 57篇 |
2010年 | 34篇 |
2009年 | 32篇 |
2008年 | 45篇 |
2007年 | 28篇 |
2006年 | 29篇 |
2005年 | 34篇 |
2004年 | 27篇 |
2003年 | 25篇 |
2002年 | 24篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1971年 | 1篇 |
1969年 | 3篇 |
排序方式: 共有674条查询结果,搜索用时 15 毫秒
661.
662.
G. Mitchell Susan Soteriou Lynne Kenney Steve Towers Cara Schumer Lisa Dillin Kevin Gus 《Zoo biology》1988,7(1):1-13
The behaviors of three different adult male–adult female pairs of golden-bellied mangabeys (Cercocebus galeritus chrysogaster) were compared. Correlates of restricted social conditions and of the presence of offspring on adult behavior and direction of aggressive behaviors were noted. A captive pair displayed self-biting and other aberrant behaviors, a lone wild-caught pair showed redirected aggression related to sex, and a pair housed with its offspring showed close social proximity and protection of an infant. The implications of housing and experience for space and visitor exposure are discussed. Observer- vs. visitor-directed displays are seen as important measures of group and visitor effects. 相似文献
663.
Biological Trace Element Research - Neutron activation analysis was used for determining trace element content in hair of herbivorous animals. Pollutant deposition from the air onto foliage must be... 相似文献
664.
665.
666.
Serry Mohamed A. Stepp Cara E. Peterson Sean D. 《Biomechanics and modeling in mechanobiology》2023,22(1):339-356
Biomechanics and Modeling in Mechanobiology - Fundamental frequency patterns during phonation onset have received renewed interest due to their promising application in objective classification of... 相似文献
667.
Biological Invasions - Disturbances such as fire provide an opportunity for invasive plant species to exploit newly created niche space. Whether initial invaders facilitate, compete with, or do not... 相似文献
668.
669.
Jana M. U'Ren Rachel E. Gallery David R. Maddison Cara M. Gibson 《Mycological Research》2009,113(4):432-449
Fungi associated with seeds of tropical trees pervasively affect seed survival and germination, and thus are an important, but understudied, component of forest ecology. Here, we examine the diversity and evolutionary origins of fungi isolated from seeds of an important pioneer tree (Cecropia insignis, Cecropiaceae) following burial in soil for five months in a tropical moist forest in Panama. Our approach, which relied on molecular sequence data because most isolates did not sporulate in culture, provides an opportunity to evaluate several methods currently used to analyse environmental samples of fungi. First, intra- and interspecific divergence were estimated for the nu-rITS and 5.8S gene for four genera of Ascomycota that are commonly recovered from seeds. Using these values we estimated species boundaries for 527 isolates, showing that seed-associated fungi are highly diverse, horizontally transmitted, and genotypically congruent with some foliar endophytes from the same site. We then examined methods for inferring the taxonomic placement and phylogenetic relationships of these fungi, evaluating the effects of manual versus automated alignment, model selection, and inference methods, as well as the quality of BLAST-based identification using GenBank. We found that common methods such as neighbor-joining and Bayesian inference differ in their sensitivity to alignment methods; analyses of particular fungal genera differ in their sensitivity to alignments; and numerous and sometimes intricate disparities exist between BLAST-based versus phylogeny-based identification methods. Lastly, we used our most robust methods to infer phylogenetic relationships of seed-associated fungi in four focal genera, and reconstructed ancestral states to generate preliminary hypotheses regarding the evolutionary origins of this guild. Our results illustrate the dynamic evolutionary relationships among endophytic fungi, pathogens, and seed-associated fungi, and the apparent evolutionary distinctiveness of saprotrophs. Our study also elucidates the diversity, taxonomy, and ecology of an important group of plant-associated fungi and highlights some of the advantages and challenges inherent in the use of ITS data for environmental sampling of fungi. 相似文献
670.
Emanuela W. A. Weidlich Cara R. Nelson John L. Maron Ragan M. Callaway Benjamin M. Delory Vicky M. Temperton 《Restoration Ecology》2021,29(1)
Priority effects refer to the order or timing of species arrival, including how species that arrive early at a site either positively or negatively affect establishment, growth, or reproduction of species that arrive later. Despite the clear implications of priority effects for ecological restoration, there have been no reviews of how and where priority effects have been studied and the extent to which findings can be applied to restoration. Here, we systematically review the literature on priority effects by (1) synthesizing information from papers that compared simultaneous and nonsimultaneous planting or sowing; (2) discussing the mechanisms through which priority effects operate, (3) considering how these mechanisms might be manipulated to achieve restoration goals; and (4) highlighting future research needed to improve the use of priority effects in restoration. In a term‐targeted search, we found 43 studies that experimentally manipulated the order of arrival of different species. Overall, these concluded that even small delays in arrival time, as opposed to simultaneous arrival of species, can promote differences in subsequent community composition as well as ecosystem functions. There were very few studies on the long‐term stability of these priority effects, and the majority were conducted in temperate grasslands. Our findings suggest that creating alternative vegetation states via priority treatments is a promising avenue for restoration. However, for the concept to be best operationalized for restoration, we need research in more ecosystems that are priorities for restoration, and treatments that are followed over extended time periods. 相似文献