全文获取类型
收费全文 | 1398篇 |
免费 | 192篇 |
出版年
2022年 | 14篇 |
2021年 | 29篇 |
2020年 | 17篇 |
2019年 | 36篇 |
2018年 | 43篇 |
2017年 | 34篇 |
2016年 | 47篇 |
2015年 | 66篇 |
2014年 | 65篇 |
2013年 | 75篇 |
2012年 | 87篇 |
2011年 | 77篇 |
2010年 | 77篇 |
2009年 | 53篇 |
2008年 | 68篇 |
2007年 | 78篇 |
2006年 | 69篇 |
2005年 | 58篇 |
2004年 | 58篇 |
2003年 | 40篇 |
2002年 | 49篇 |
2001年 | 26篇 |
2000年 | 44篇 |
1999年 | 28篇 |
1998年 | 21篇 |
1997年 | 9篇 |
1996年 | 18篇 |
1995年 | 10篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 19篇 |
1991年 | 22篇 |
1990年 | 21篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 15篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1980年 | 9篇 |
1977年 | 12篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1973年 | 8篇 |
1972年 | 9篇 |
1971年 | 5篇 |
1969年 | 9篇 |
1967年 | 7篇 |
排序方式: 共有1590条查询结果,搜索用时 31 毫秒
51.
Fuentes Antón S. Reyes E. Sánchez de la Cruz D. Rodríguez Sánchez A. García Dávila I. Sánchez J. Sánchez 《Aerobiologia》2021,37(4):809-824
Aerobiologia - The purpose of this study is to contribute to the knowledge about fungal spores in the atmosphere of the city of Salamanca (Middle West Spain), through the comparative study of... 相似文献
52.
53.
54.
55.
Philip Cooper Alan W. Walker Jorge Reyes Martha Chico Susannah J. Salter Maritza Vaca Julian Parkhill 《PloS one》2013,8(10)
Background
The soil-transmitted helminth (STH), Trichuris trichiura colonises the human large intestine where it may modify inflammatory responses, an effect possibly mediated through alterations in the intestinal microbiota. We hypothesised that patent T. trichiura infections would be associated with altered faecal microbiota and that anthelmintic treatment would induce a microbiota resembling more closely that observed in uninfected individuals.Materials and Methods
School children in Ecuador were screened for STH infections and allocated to 3 groups: uninfected, T. trichiura only, and mixed infections with T. trichiura and Ascaris lumbricoides. A sample of uninfected children and those with T. trichiura infections only were given anthelmintic treatment. Bacterial community profiles in faecal samples were studied by 454 pyrosequencing of 16 S rRNA genes.Results
Microbiota analyses of faeces were done for 97 children: 30 were uninfected, 17 were infected with T. trichiura, and 50 with T. trichiura and A. lumbricoides. Post-treatment samples were analyzed for 14 children initially infected with T. trichiura alone and for 21 uninfected children. Treatment resulted in 100% cure of STH infections. Comparisons of the microbiota at different taxonomic levels showed no statistically significant differences in composition between uninfected children and those with T. trichiura infections. We observed a decreased proportional abundance of a few bacterial genera from the Clostridia class of Firmicutes and a reduced bacterial diversity among children with mixed infections compared to the other two groups, indicating a possible specific effect of A. lumbricoides infection. Anthelmintic treatment of children with T. trichiura did not alter faecal microbiota composition.Discussion
Our data indicate that patent human infections with T. trichiura may have no effect on faecal microbiota but that A. lumbricoides colonisation might be associated with a disturbed microbiota. Our results also catalogue the microbiota of rural Ecuadorians and indicate differences with individuals from more urban industrialised societies. 相似文献56.
57.
Hernández-Ledesma Ana Laura Rodríguez-Méndez Adriana Jheny Gallardo-Vidal Lilia Susana García-Gasca Teresa Alatorre-Cruz Julia María García-Solís Pablo López Reyes Julián Solís-Saínz Juan Carlos 《Molecular biology reports》2020,47(12):9667-9676
Molecular Biology Reports - Although cognitive impairment (CI) is classically associated with aging, it has been proposed that neurological pathologies may increase the risk to suffer CI. Despite... 相似文献
58.
Reyes Babiano Gwenael Badis Cosmin Saveanu Abdelkader Namane Antonia Doyen Antonio Díaz-Quintana Alain Jacquier Micheline Fromont-Racine Jesús de la Cruz 《Nucleic acids research》2013,41(20):9461-9470
Ribosome biogenesis requires >300 assembly factors in Saccharomyces cerevisiae. Ribosome assembly factors Imp3, Mrt4, Rlp7 and Rlp24 have sequence similarity to ribosomal proteins S9, P0, L7 and L24, suggesting that these pre-ribosomal factors could be placeholders that prevent premature assembly of the corresponding ribosomal proteins to nascent ribosomes. However, we found L7 to be a highly specific component of Rlp7-associated complexes, revealing that the two proteins can bind simultaneously to pre-ribosomal particles. Cross-linking and cDNA analysis experiments showed that Rlp7 binds to the ITS2 region of 27S pre-rRNAs, at two sites, in helix III and in a region adjacent to the pre-rRNA processing sites C1 and E. However, L7 binds to mature 25S and 5S rRNAs and cross-linked predominantly to helix ES7Lb within 25S rRNA. Thus, despite their predicted structural similarity, our data show that Rlp7 and L7 clearly bind at different positions on the same pre-60S particles. Our results also suggest that Rlp7 facilitates the formation of the hairpin structure of ITS2 during 60S ribosomal subunit maturation. 相似文献
59.
Chiral sulfoxides/N‐oxides (R)‐ 1 and (R,R)‐ 2 are effective chiral promoters in the enantioselective allylation of α‐keto ester N‐benzoylhydrazone derivatives 3a , 3b , 3c , 3d , 3e , 3f , 3g to generate the corresponding N‐benzoylhydrazine derivatives 4a , 4b , 4c , 4d , 4e , 4f , 4g , with enantiomeric excesses as high as 98%. Representative hydrazine derivatives 4a , 4b were subsequently treated with SmI2, and the resulting amino esters 5a , 5b with LiOH to obtain quaternary α‐substituted α‐allyl α‐amino acids 6a , 6b , whose absolute configuration was assigned as (S), with fundament on chemical correlation and electronic circular dichroism (ECD) data. Chirality 25:529–540, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
60.