全文获取类型
收费全文 | 3248篇 |
免费 | 211篇 |
国内免费 | 151篇 |
专业分类
3610篇 |
出版年
2024年 | 17篇 |
2023年 | 70篇 |
2022年 | 150篇 |
2021年 | 259篇 |
2020年 | 179篇 |
2019年 | 224篇 |
2018年 | 206篇 |
2017年 | 141篇 |
2016年 | 208篇 |
2015年 | 263篇 |
2014年 | 350篇 |
2013年 | 341篇 |
2012年 | 336篇 |
2011年 | 289篇 |
2010年 | 146篇 |
2009年 | 114篇 |
2008年 | 107篇 |
2007年 | 86篇 |
2006年 | 43篇 |
2005年 | 37篇 |
2004年 | 22篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有3610条查询结果,搜索用时 15 毫秒
101.
Haiye Luan Baojian Guo Yuhan Pan Chao Lv Huiquan Shen Rugen Xu 《Plant Growth Regulation》2018,85(3):399-409
Waterlogging is one of the major stresses limiting crop production worldwide. The understanding of the mechanisms of plant adaptations to waterlogging stress helps improve plant tolerance to stress. In this study, physiological responses and morpho-anatomical adaptations of seven different barley genotypes were investigated under waterlogging stress. The results showed that the waterlogging-tolerant varieties (TX9425, Yerong, TF58) showed less reduction in plant height, SPAD (soil–plant analyses development analyses) value, tillers, shoot and root biomasses than did the waterlogging-sensitive varieties (Franklin, Naso Nijo, TF57). Under waterlogging stress condition, the tolerant genotypes also showed a much larger number of adventitious roots than did the sensitive genotypes. More intercellular spaces and better integrated chloroplast membrane structures were observed in the leaves of the waterlogging-tolerant cultivars, which is likely due to increased ethylene content, decreased ABA content and less accumulation of O2.?. The ability to form new adventitious roots and intercellular spaces in shoots can also be used as selection criteria in breeding barley for waterlogging tolerance. 相似文献
102.
103.
Improved production of citric acid by Yarrowia lipolytica using oleic acid as the oxygen‐vector and co‐substrate 下载免费PDF全文
Xiaoyan Liu Jiaxing Xu Jun Xia Jinshun Lv Zhen Wu Yuanfang Deng 《Engineering in Life Science》2016,16(5):424-431
Yarrowia lipolytica is able to secrete large amounts of citric acid (CA), which is greatly affected by the dissolved oxygen concentration (DOC) in the fermentation medium. In this study, oleic acid was selected as oxygen‐vector to improve DOC during CA fermentation. When 2% (v/v) of oleic acid was added to the culture broth, higher DOC (>42.1%) was determined throughout the CA synthesis phase. The yield of CA reached a maximum of 32.1 g/L (25.4% higher than the control) and the biomass was 8.8 g/L. The substrate uptake rate, products formation rate and key enzyme activities were also determined, and the results indicated that CA synthesis was strengthened with oleic acid addition. Furthermore, it was detected that oleic acid could be assimilated by the cells, which means that oleic acid could be served both as oxygen‐vector and co‐substrate for CA synthesis by Y. lipolytica. In a bioreactor with working volume of 3 L, the highest concentration of CA reached to 36. 4 g/L in the presence of 2% (v/v) oleic acid after 192 h of fermentation. These results confirmed that oleic acid could be applied in the large‐scale production of CA by Y. lipolytica. 相似文献
104.
105.
Qingqing Feng Lu Han Xu Tan Yali Zhang Tianyi Meng Jun Lu Jie Lv 《Current microbiology》2016,73(6):924-929
106.
107.
108.
Isolation and characterization of phenanthrene-degrading <Emphasis Type="Italic">Sphingomonas paucimobilis</Emphasis> strain ZX4 总被引:3,自引:0,他引:3
Phenanthrene-degrading bacterium strain ZX4 was isolated from an oil-contaminated soil, and identified as Sphingomonas paucimobilis based on 16S rDNA sequence, cellular fatty acid composition, mol% G + C and Biolog-GN tests. Besides phenanthrene, strain ZX4 could also utilize naphthalene, fluorene and other aromatic compounds. The growth on salicylic acid and catechol showed that the strain degraded phenanthrene via salicylate pathway, while the assay of catechol 2, 3-dioxygenase revealed catechol could be metabolized through meta-cleavage pathway. Three genes, including two of meta-cleavage operon genes and one of GST encoding gene were obtained. The order of genes arrangement was similar to S-type meta-pathway operons. The phylogenetic trees based on 16S rDNA sequence and meta-pathway gene both revealed that strain ZX4 is clustered with strains from genus Sphingomonas. 相似文献
109.
110.
We assessed SLC27A1, a candidate gene for milk production traits in Chinese Holstein cattle. DNA was extracted from the blood of 48 top Chinese Holstein Cattle selected according to phenotypic character and mixed into DNA pool for SNP detection. We tested blood samples of these cattle for SNPs in exon 3 and the 3'-flanking region of the SLC27A1 gene by using polymerase chain reaction-single-stranded conformation polymorphism (PCR-SSCP) and DNA sequencing. We found 2 polymorphic sites: 112T>C, a synonymous mutation, in exon 3 (SNP(1)), and 64G>A in the 3'-UTR (SNP(2)). We also determined the genotypes of 330 Chinese Holstein cattle by using PCR-restriction fragment length polymorphism (RFLP). We found 3 genotypes each at SNP(1) (TT, TC, and CC) and SNP(2) (GG, GA, and AA). The association among the different genotypes at these 2 sites and milk production traits was analyzed using a least-squares procedure. The results showed that cows with genotype CC had higher milk yields than those with genotype TC (0.01 < p < 0.05). No significant difference was detected among the 3 SNP(2) genotypes in terms of milk production traits. Our results provide evidence that the C allele have potential effects on milk yield trait. 相似文献