全文获取类型
收费全文 | 404篇 |
免费 | 45篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 15篇 |
2019年 | 4篇 |
2018年 | 14篇 |
2017年 | 21篇 |
2016年 | 22篇 |
2015年 | 33篇 |
2014年 | 49篇 |
2013年 | 32篇 |
2012年 | 43篇 |
2011年 | 36篇 |
2010年 | 25篇 |
2009年 | 21篇 |
2008年 | 19篇 |
2007年 | 13篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 10篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1994年 | 2篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
排序方式: 共有449条查询结果,搜索用时 574 毫秒
61.
62.
63.
64.
Anagaw Atickem Getachew Simeneh Afework Bekele Tariku Mekonnen Claudio Sillero‐Zubiri Russell A. Hill Nils Chr. Stenseth 《African Journal of Ecology》2017,55(4):632-639
The African wolf (Canis lupus lupaster) was first identified in 2011 in the Ethiopian highlands, with its status as a new species confirmed in 2015. We studied the diet of a confirmed African wolf population in the Menz‐Guassa Community Conservation Area of central Ethiopia from scat samples collected by den sites from August to November 2010. Rodents were found to be the principal food items occurring in 88.1% of scats (n = 101), followed by plant material (34.7%) and insects (21.8%). Information on reported livestock predation and ensuing conflict with the agro‐pastoral community was obtained through a questionnaire survey. Interview respondents listed the African wolf as the most serious predator of livestock, accounting for 74.6% of the reported kills (n = 492) and 78.9% of the economic loss. Over 70% of reported livestock predation occurred during the dry season (January–April). Better livestock management during this period may significantly reduce conflict. As sympatric Ethiopian wolves primarily feed on rodents, further studies on the foraging ecology, niche overlap and interspecific interactions between the two species should be studied to determine the extent of competition between the two species. 相似文献
65.
Patterns of seasonality and group membership characterize the gut microbiota in a longitudinal study of wild Verreaux's sifakas (Propithecus verreauxi) 下载免费PDF全文
Andrea Springer Claudia Fichtel Gabriel A. Al‐Ghalith Flávia Koch Katherine R. Amato Jonathan B. Clayton Dan Knights Peter M. Kappeler 《Ecology and evolution》2017,7(15):5732-5745
The intestinal microbiota plays a major role in host development, metabolism, and health. To date, few longitudinal studies have investigated the causes and consequences of microbiota variation in wildlife, although such studies provide a comparative context for interpreting the adaptive significance of findings from studies on humans or captive animals. Here, we investigate the impact of seasonality, diet, group membership, sex, age, and reproductive state on gut microbiota composition in a wild population of group‐living, frugi‐folivorous primates, Verreaux's sifakas (Propithecus verreauxi). We repeatedly sampled 32 individually recognizable animals from eight adjacent groups over the course of two different climatic seasons. We used high‐throughput sequencing of the 16S rRNA gene to determine the microbiota composition of 187 fecal samples. We demonstrate a clear pattern of seasonal variation in the intestinal microbiota, especially affecting the Firmicutes‐Bacteroidetes ratio, which may be driven by seasonal differences in diet. The relative abundances of certain polysaccharide‐fermenting taxa, for example, Lachnospiraceae, were correlated with fruit and fiber consumption. Additionally, group membership influenced microbiota composition independent of season, but further studies are needed to determine whether this pattern is driven by group divergences in diet, social contacts, or genetic factors. In accordance with findings in other wild mammals and primates with seasonally fluctuating food availability, we demonstrate seasonal variation in the microbiota of wild Verreaux's sifakas, which may be driven by food availability. This study adds to mounting evidence that variation in the intestinal microbiota may play an important role in the ability of primates to cope with seasonal variation in food availability. 相似文献
66.
Background
The evolutionary history of the Asian colobines is less understood. Although monophyly of the odd-nosed monkeys was recently confirmed, the relationships among the langur genera Presbytis, Semnopithecus and Trachypithecus and their position among Asian colobines remained unclear. Moreover, in Trachypithecus various species groups are recognized, but their affiliations are still disputed. To address these issues, mitochondrial and Y chromosomal sequence data were phylogenetically related and combined with presence/absence analyses of retroposon integrations. 相似文献67.
Edward T. Mee Neil Berry Claire Ham Ulrike Sauermann Maria T. Maggiorella Frédéric Martinon Ernst J. Verschoor Jonathan L. Heeney Roger Le Grand Fausto Titti Neil Almond Nicola J. Rose 《Immunogenetics》2009,61(5):327-339
The restricted diversity of the major histocompatibility complex (MHC) of Mauritian cynomolgus macaques provides powerful
opportunities for insight into host-viral interactions and cellular immune responses that restrict lentiviral infections.
However, little is known about the effects of Mhc haplotypes on control of SIV in this species. Using microsatellite-based
genotyping and allele-specific PCR, Mhc haplotypes were deduced for 35 macaques infected with the same stock of SIVmac251.
Class I haplotype H6 was associated with a reduction in chronic phase viraemia (p = 0.0145) while a similar association was observed for H6 class II (p = 0.0063). An increase in chronic phase viraemia, albeit an insignificant trend, was observed in haplotype H5-positive animals.
These results further emphasise the value of genetically defined populations of non-human primates in AIDS research and provide
a foundation for detailed characterisation of MHC restricted cellular immune responses and the effects of host genetics on
SIV replication in cynomolgus macaques.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
68.
Roman A. Siddiqui Ulrike Sauermann Janine Altmüller Michael Nothnagel Jacques Fellay Christiane Stahl-Hennig Michael Krawczak 《American journal of human genetics》2009,85(2):228-1226
AIDS has changed from a mostly male-specific health problem to one that predominantly affects females. Although sex differences in HIV-1 susceptibility are beyond doubt, the extent to which sex affects the onset and progression of AIDS has remained elusive. Here, we provide evidence for an influence of X chromosomal variation on the course of retroviral infection, both in HIV-1-infected patients and in the rhesus macaque model of AIDS. A two-stage, microsatellite-based GWAS of SIV-infected monkeys revealed MHC class I markers and a hitherto-unknown X chromosomal locus as being associated with a nominal score measuring progression to AIDS (Fisher''s exact p < 10−6). The X chromosomal association was subsequently confirmed in HIV-1-infected patients with published SNP genotype data. SNP rs5968255, located at human Xq21.1 in a conserved sequence element near the RPS6KA6 and CYLC1 genes, was identified as a significant genetic determinant of disease progression in females (ANOVA p = 8.8 × 10−5), but not in males (p = 0.19). Heterozygous female carriers of the C allele showed significantly slower CD4 cell decline and a lower viral load at set point than TT homozygous females and than males. Inspection of HapMap revealed that the CT genotype is significantly more frequent among Asians than among Europeans or Africans. Our results suggest that, in addition to the individual innate and adaptive immunity status, sex-linked genetic variation impacts upon the rate of progression to AIDS. Elucidating the mechanisms underlying this sex-specific effect will promote the development of antiretroviral therapies with high efficacy in both sexes. 相似文献
69.
70.
《Arthropod Structure & Development》2017,46(2):274-286
Because of the poor knowledge of the morphology of the female reproductive organs of most brachyuran crabs, this study investigated two Atlantic representatives of the family Leucosiidae, Ilia nucleus (Linnaeus, 1758) and Persephona mediterranea (Herbst, 1794), using histological methods and magnetic resonance imaging (MRI). While the vagina conforms to the concave type, the arrangement of the two chambers of the seminal receptacle differs strongly from that of other eubrachyuran sperm storage organs. Both chambers are oriented laterally within the crab's body. This is in contrast to the dorso-ventral orientation described in most other known brachyuran crabs. The lateral chamber is covered by cuticle, whereas the medial chamber is covered by a holocrine glandular epithelium. The oviduct connection is located ventrally, posterior to the vagina. The oviduct orifice is characterized by a transition from the epithelium lining the oviduct to the seminal receptacle's holocrine glandular epithelium. Moreover, muscle fibres are attached to the oviduct orifice and to the sternal cuticle. This musculature can be interpreted as an important feature in the fertilization and egg-laying process by supporting and controlling the inflow of eggs into the seminal receptacle lumen. The results of this study are compared to the morphology of the seminal receptacle of another leucosiid crab, Ebalia tumefacta (Montagu, 1808), and to those of other known eubrachyuran crabs. 相似文献