全文获取类型
收费全文 | 879篇 |
免费 | 98篇 |
出版年
2021年 | 13篇 |
2018年 | 13篇 |
2017年 | 6篇 |
2016年 | 21篇 |
2015年 | 42篇 |
2014年 | 27篇 |
2013年 | 37篇 |
2012年 | 49篇 |
2011年 | 41篇 |
2010年 | 30篇 |
2009年 | 30篇 |
2008年 | 35篇 |
2007年 | 58篇 |
2006年 | 32篇 |
2005年 | 27篇 |
2004年 | 42篇 |
2003年 | 35篇 |
2002年 | 23篇 |
2001年 | 17篇 |
2000年 | 29篇 |
1999年 | 18篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 13篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 21篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 15篇 |
1985年 | 11篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 19篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1974年 | 7篇 |
1973年 | 11篇 |
1972年 | 6篇 |
1966年 | 5篇 |
1961年 | 5篇 |
1942年 | 6篇 |
排序方式: 共有977条查询结果,搜索用时 15 毫秒
31.
A fundamental question concerning group-living species is what factors influence the evolution of sociality. Although several studies link adult social bonds to fitness, social patterns and relationships are often formed early in life and are also likely to have fitness consequences, particularly in species with lengthy developmental periods, extensive social learning, and early social bond-formation. In a longitudinal study of bottlenose dolphins (Tursiops sp.), calf social network structure, specifically the metric eigenvector centrality, predicted juvenile survival in males. Additionally, male calves that died post-weaning had stronger ties to juvenile males than surviving male calves, suggesting that juvenile males impose fitness costs on their younger counterparts. Our study indicates that selection is acting on social traits early in life and highlights the need to examine the costs and benefits of social bonds during formative life history stages. 相似文献
32.
33.
34.
B. Lakshminarayanan C.M. Guinane P.M. O'Connor M. Coakley C. Hill C. Stanton P.W. O'Toole R.P. Ross 《Journal of applied microbiology》2013,114(3):886-898
Aims
To isolate and characterize bacteriocins produced by predominant species of lactic acid bacteria from faeces of elderly subjects.Methods and Results
Screening over 70 000 colonies, from faecal samples collected from 266 subjects, using the indicator organisms Lactobacillus bulgaricus LMG 6901 and Listeria innocua DPC 3572, identified 55 antimicrobial‐producing bacteria. Genomic fingerprinting following ApaI digestion revealed 15 distinct strains. The antimicrobial activities associated with 13 of the 15 strains were sensitive to protease treatment. The predominant antimicrobial‐producing species were identified as Lactobacillus salivarius, Lactobacillus gasseri, Lactobacillus acidophilus, Lactobacillus crispatus and Enterococcus spp. A number of previously characterized bacteriocins, including ABP‐118 and salivaricin B (from Lact. salivarius), enterocin B (Enterococcus faecium), lactacin B (Lact. acidophilus), gassericin T and a variant of gassericin A (Lact. gasseri), were identified. Interestingly, two antimicrobial‐producing species, not generally associated with intestinally derived microorganisms were also isolated: Lactococcus lactis producing nisin Z and Streptococcus mutans producing mutacin II.Conclusion
These data suggest that bacteriocin production by intestinal isolates against our chosen targets under the screening conditions used was not frequent (0·08%).Significance and Impact of the Study
The results presented are important due to growing evidence indicating bacteriocin production as a potential probiotic trait by virtue of strain dominance and/or pathogen inhibition in the mammalian intestine. 相似文献35.
36.
Zhinxin Zhao Roberto Gambari Kenneth Ka-Ho Lee Stanton Hon-Lung Kok Raymond Siu-Ming Wong Fung-Yi Lau Johnny Cheuk-On Tang Kim-Hung Lam Chor-Hing Cheng Desmond Kwok Po Hau Chung-Hin Chui Wai-Yeung Wong Wai-Kwok Wong 《Bioorganic & medicinal chemistry letters》2013,23(8):2373-2376
We explore the possible cellular cytotoxic activity of an amphiphilic silicon(IV) phthalocyanine with axially ligated rhodamine B under ambient light experimental environment as well as its in vivo antitumour potential using Hep3B hepatoma cell model. After loading into the Hep3B hepatoma cells, induction of cellular cytotoxicity and cell cycle arrest were detected. Strong growth inhibition of tumour xenograft together with significant tumour necrosis and limited toxicological effects exerted on the nude mice could be identified. 相似文献
37.
38.
Anil Chekuri Katarzyna Zientara‐Rytter Angel Soto‐Hermida Shyamanga Borooah Marina Voronchikhina Pooja Biswas Virender Kumar David Goodsell Caroline Hayward Peter Shaw Chloe Stanton Donita Garland Suresh Subramani Radha Ayyagari 《Aging cell》2019,18(6)
Late‐onset retinal degeneration (L‐ORD) is an autosomal dominant macular degeneration characterized by the formation of sub‐retinal pigment epithelium (RPE) deposits and neuroretinal atrophy. L‐ORD results from mutations in the C1q‐tumor necrosis factor‐5 protein (CTRP5), encoded by the CTRP5/C1QTNF5 gene. To understand the mechanism underlying L‐ORD pathology, we used a human cDNA library yeast two‐hybrid screen to identify interacting partners of CTRP5. Additionally, we analyzed the Bruch's membrane/choroid (BM‐Ch) from wild‐type (Wt), heterozygous S163R Ctrp5 mutation knock‐in (Ctrp5S163R/wt), and homozygous knock‐in (Ctrp5S163R/S163R) mice using mass spectrometry. Both approaches showed an association between CTRP5 and HTRA1 via its C‐terminal PDZ‐binding motif, stimulation of the HTRA1 protease activity by CTRP5, and CTRP5 serving as an HTRA1 substrate. The S163R‐CTRP5 protein also binds to HTRA1 but is resistant to HTRA1‐mediated cleavage. Immunohistochemistry and proteomic analysis showed significant accumulation of CTRP5 and HTRA1 in BM‐Ch of Ctrp5S163R/S163R and Ctrp5S163R/wt mice compared with Wt. Additional extracellular matrix (ECM) components that are HTRA1 substrates also accumulated in these mice. These results implicate HTRA1 and its interaction with CTRP5 in L‐ORD pathology. 相似文献
39.
40.