全文获取类型
收费全文 | 382篇 |
免费 | 53篇 |
出版年
2021年 | 4篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 9篇 |
2014年 | 20篇 |
2013年 | 12篇 |
2012年 | 18篇 |
2011年 | 16篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 14篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 11篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1979年 | 3篇 |
1978年 | 12篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1974年 | 9篇 |
1973年 | 8篇 |
1972年 | 5篇 |
1971年 | 8篇 |
1970年 | 6篇 |
1969年 | 7篇 |
1967年 | 6篇 |
1966年 | 4篇 |
1965年 | 4篇 |
1964年 | 3篇 |
排序方式: 共有435条查询结果,搜索用时 570 毫秒
101.
Heather E. Watts Lisa M. Blankenship Stephanie E. Dawes Kay E. Holekamp 《Ethology : formerly Zeitschrift fur Tierpsychologie》2010,116(12):1199-1209
Competition among mammalian carnivores can be particularly intense and can influence population dynamics at lower trophic levels. One strategy employed by carnivores to minimize potentially costly interspecific competition is avoidance of dominant species. Recent research has highlighted the importance of consistent individual differences in behavior (i.e. temperament traits) in understanding behavioral variation during predator–prey interactions and intraspecific interactions. However, the importance of such individual differences to interspecific competition has received little attention. Here, we examined the responses of spotted hyenas (Crocuta crocuta) to their primary competitors, African lions (Panthera leo), to (1) determine whether hyenas avoid lions and (2) evaluate the potential importance of individual differences in behavior during interspecific competition. Spotted hyenas and lions co‐occur throughout much of Africa and are vigorous competitors. Whereas lions sometimes kill hyenas and steal their food, lions also represent a source of food for hyenas via scavenging. Using audio playback experiments, we found that hyenas do not uniformly avoid potential encounters with lions. Indeed, we noted considerable variation among individuals in their responses to lion roars, and this variation reflected consistent individual differences in risk‐taking and vigilance tendencies. Individual differences in vigilance behavior were specific to interactions with lions. We conclude that individual differences in behavior have the potential to play an important role in determining the nature and outcome of interspecific competition. 相似文献
102.
103.
John R Glossop Richard D Emes Richard D Emes Nicola B Nixon Nicola B Nixon Kim E Haworth Kim E Haworth Jon C Packham Jon C Packham Peter T Dawes Peter T Dawes Anthony A Fryer Anthony A Fryer Derek L Mattey Derek L Mattey William E Farrell William E Farrell 《Epigenetics》2014,9(9):1228-1237
Changes to the DNA methylome have been described in patients with rheumatoid arthritis (RA). In previous work, we reported genome-wide methylation differences in T-lymphocyte and B-lymphocyte populations from healthy individuals. Now, using HumanMethylation450 BeadChips to interrogate genome-wide DNA methylation, we have determined disease-associated methylation changes in blood-derived T- and B-lymphocyte populations from 12 female patients with seropositive established RA, relative to 12 matched healthy individuals. Array data were analyzed using NIMBL software and bisulfite pyrosequencing was used to validate array candidates. Genome-wide DNA methylation, determined by analysis of LINE-1 sequences, revealed higher methylation in B-lymphocytes compared with T-lymphocytes (P ≤ 0.01), which is consistent with our findings in healthy individuals. Moreover, loci-specific methylation differences that distinguished T-lymphocytes from B-lymphocytes in healthy individuals were also apparent in RA patients. However, disease-associated methylation differences were also identified in RA. In these cases, we identified 509 and 252 CpGs in RA-derived T- and B-lymphocytes, respectively, that showed significant changes in methylation compared with their cognate healthy counterparts. Moreover, this included a restricted set of 32 CpGs in T-lymphocytes and 20 CpGs in B-lymphocytes (representing 15 and 10 genes, respectively, and including two, MGMT and CCS, that were common to both cell types) that displayed more substantial changes in methylation. These changes, apparent as hyper- or hypo-methylation, were independently confirmed by pyrosequencing analysis. Validation by pyrosequencing also revealed additional sites in some candidate genes that also displayed altered methylation in RA. In this first study of genome-wide DNA methylation in individual T- and B-lymphocyte populations in RA patients, we report disease-associated methylation changes that are distinct to each cell type and which support a role for discrete epigenetic regulation in this disease. 相似文献
104.
Three forms of the iota-producing carrageenophyte,Eucheuma denticulatum, and four forms of the kappa-producing carrageenophyte,Kappaphycus alvarezii, obtained from seaweed farms in the Philippines have been grown in the laboratory under unialgal and axenic conditions. Comparison of media indicates that seed stocks of both species can be cultured using enriched seawater media ranging from ESS and SWMD-1 to inexpensive soil extract (Erdshreiber's) or holding in sterile seawater for up to three weeks. Micropropagation has been successful with at least two forms of each species resulting in clonal propagation from axenic explants within 4 to 8 weeks. Callus development and branch regeneration has also been induced in two forms of each species. The results indicate that culture facilities in the farming areas of the Philippines could maintain high-yielding and rapidly growing seed stock for the seaweed farmers. 相似文献
105.
C. P. Dawes 《Journal of applied phycology》1995,7(3):303-313
Suspended rope cultivation systems for Gracilaria or Gracilariopsis can be seeded from spores but vegetative propagation is used for those which are currently commercially successful. Such
systems and methods have been recently developed for the shallow lagoon areas around Lüderitz, Namibia and deeper open water
sites off the Araya Peninsula, Venezuela. Various sites, substrata, depths and seeding methods have been assessed and have
resulted in average commercial growth rates of about 3.5% per day. Netlon ‘Superope’ has been demonstrated to be more suitable
than laid rope as a substratum for outplanted vegetative Gracilaria gracilis in Namibia as it does not compress the thalli as they grow. An efficient method, using hooks, has been developed to ‘seed’
the Superope. There is a very low incidence of algal epiphytism: mainly Ceramium and Ulva sp. In Venezuela, pilot rope cultivation systems for Gracilariopsis tenuifrons proved successful and have good commercial prospects. 相似文献
106.
107.
Joan Dawes 《Journal of bacteriology》1976,127(2):1024-1025
Many members of the Enterobacteriaceae, but not other gram-negative organisms, apparently carry a specific recognition site for the T4 tail tube on their cytoplasmic membranes. 相似文献
108.
109.
110.