全文获取类型
收费全文 | 1915篇 |
免费 | 167篇 |
国内免费 | 188篇 |
出版年
2024年 | 5篇 |
2023年 | 42篇 |
2022年 | 62篇 |
2021年 | 105篇 |
2020年 | 65篇 |
2019年 | 73篇 |
2018年 | 74篇 |
2017年 | 58篇 |
2016年 | 86篇 |
2015年 | 91篇 |
2014年 | 145篇 |
2013年 | 176篇 |
2012年 | 130篇 |
2011年 | 78篇 |
2010年 | 61篇 |
2009年 | 86篇 |
2008年 | 75篇 |
2007年 | 80篇 |
2006年 | 97篇 |
2005年 | 75篇 |
2004年 | 91篇 |
2003年 | 95篇 |
2002年 | 74篇 |
2001年 | 43篇 |
2000年 | 43篇 |
1999年 | 31篇 |
1998年 | 34篇 |
1997年 | 29篇 |
1996年 | 30篇 |
1995年 | 13篇 |
1994年 | 23篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 5篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1979年 | 2篇 |
排序方式: 共有2270条查询结果,搜索用时 15 毫秒
1.
2.
A hierarchical breeding design was used to determine if winter flounder Pseudopleuronectes americanus embryos and yolk-sac larvae sired by Georges Bank males developed and grew larger than fish sired by Passamaquoddy Bay males, and to examine parental contributions to variations in fertilization success, time to 50% hatch, hatch success and larval morphological development. Significant stock effects were detected for time to hatch and larval development. Eggs fertilized by Passamaquoddy Bay males reached 50% hatch significantly earlier than eggs fertilized by Georges Bank males. Larvae sired by Georges Bank males were significantly larger during larval development for four of the six traits measured at 12 days post-hatch: head depth, jaw length, myotome height and body area. Embryo and larval development were strongly influenced by maternal contributions; there were significant maternal variance components for the majority of the variables measured. Paternal variance components were significant for fertilization success, time to hatch, larval jaw length and larval head depth, however, they acted principally through parental interactions. This information has important implications for the long-term sustainable development of winter flounder for aquaculture purposes as well as for understanding winter flounder genetic variation in the wild. 相似文献
3.
Ronald E. Koes Cornelis E. Spelt Jos N. M. Mol Anton G. M. Gerats 《Plant molecular biology》1987,10(2):159-169
Chalcone synthase (CHS) genes in Petunia hybrida comprise a multigene family containing at least 7 complete members in the strain Violet 30 (V30). Based on a high sequence homology in both coding and non-coding sequence, a number of CHS genes can be placed into two subfamilies. By restriction fragment length polymorphism (RFLP) analysis it was shown that both chromosomes II and V carry one of these subfamilies, in addition to the other CHS genes identified so far. Members of a subfamily were found to be closely linked genetically. Analysis of the Petunia species that contributed to the hybrid nature of P. hybrida (P. axillaris, P. parodii, P. inflata and P. violacea) shows that none of the CHS gene clusters is specific for either one of the parents and therefore did not arise as a consequence of the hybridization. The number of CHS genes within a subfamily varies considerably among these Petunia species. From this we infer that the CHS subfamilies arose from very recent gene duplications. 相似文献
4.
Summary A method for isolating high quality DNA from wholeEuglena cells is described. The procedure consists in: the weakening of the cell pellicle in glycerol avoiding the mechanical disruption of cells and shearing damage in DNA molecules; the decondensation ofEuglena compact chromatin directly inside the cells; the complete dissociation of cells and nucleoproteins in sarkosyl detergent; the optional digestion of proteins and RNA with DNase-free enzymes and the final purification of DNA by isopycnic banding in CsCl gradients. Degradation of DNA is prevented all along the extraction procedure by glycerol, antioxydants, EDTA and sarkosyl detergent. Using the enzymatic digestion step, DNA containing few single-stranded nicks is obtained with a yield approaching 100%. DNA with no single-stranded nick could be obtained with a 35% yield when the enzymatic digestion step was omitted. In both cases, the double-stranded DNA has an average molecular weight equal or greater than 6×107. It is free of contaminants and could be easily digested with restriction enzymes. After digestion with Eco RI and size-fractionation in agarose gel this DNA has permitted specific hybridization of the rDNA sequences with a radioactive rRNA probe.Abbreviations Kbp
kilobasepairs
- Kb
kilobases 相似文献
5.
Ronald E. Koes Cornelis E. Spelt Jos N. M. Mol Anton G. M. Gerats 《Plant molecular biology》1988,10(4):375-385
Chalcone synthase (CHS) genes in Petunia hybrida comprise a multigene family containing at least 7 complete members in the strain Violet 30 (V30). Based on a high sequence homology in both coding and non-coding sequence, a number of CHS genes can be placed into two subfamilies. By restriction fragment length polymorphism (RFLP) analysis it was shown that both chromosomes II and V carry one of these subfamilies, in addition to the other CHS genes identified so far. Members of a subfamily were found to be closely linked genetically. Analysis of the Petunia species that contributed to the hybrid nature of P. hybrida (P. axillaris, P. parodii, P. inflata and P. violacea) shows that none of the CHS gene clusters is specific for either one of the parents and therefore did not arise as a consequence of the hybridization. The number of CHS genes within a subfamily varies considerably among these Petunia species. From this we infer that the CHS subfamilies arose from very recent gene duplications. 相似文献
6.
7.
8.
9.
10.
Kaijiro Anzai Shunsuke Kobayashi Narumi Kitamura Yuri Kanai Hiromichi Nakajima Yoshioki Suehiro Sataro Goto 《Journal of neurochemistry》1986,47(3):673-677
We isolated a mouse genomic clone that hybridized with small RNA present in the cytoplasm of the brain. The RNA was about 150 nucleotides long. This RNA seemed to be specific to the brain, since it was not found in the liver or kidney. The clone DNA contained a sequence homologous to 82-nucleotide "identifier" core sequence of cDNA clones of rat. The sequence contained a split promoter for RNA polymerase III and was flanked by a 12-nucleotide direct repeat (ATAAATAATTTA). 相似文献