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排序方式: 共有74条查询结果,搜索用时 245 毫秒
11.
Chantret N Salse J Sabot F Bellec A Laubin B Dubois I Dossat C Sourdille P Joudrier P Gautier MF Cattolico L Beckert M Aubourg S Weissenbach J Caboche M Leroy P Bernard M Chalhoub B 《Journal of molecular evolution》2008,66(2):138-150
We study here the evolution of genes located in the same physical locus using the recently sequenced Ha locus in seven wheat genomes in diploid, tetraploid, and hexaploid species and compared them with barley and rice orthologous regions. We investigated both the conservation of microcolinearity and the molecular evolution of genes, including coding and noncoding sequences. Microcolinearity is restricted to two groups of genes (Unknown gene-2, VAMP, BGGP, Gsp-1, and Unknown gene-8 surrounded by several copies of ATPase), almost conserved in rice and barley, but in a different relative position. Highly conserved genes between wheat and rice run along with genes harboring different copy numbers and highly variable sequences between close wheat genomes. The coding sequence evolution appeared to be submitted to heterogeneous selective pressure and intronic sequences analysis revealed that the molecular clock hypothesis is violated in most cases. 相似文献
12.
A major locus expressed in the male gametophyte with incomplete penetrance is responsible for in situ gynogenesis in maize 总被引:3,自引:0,他引:3
Barret P Brinkmann M Beckert M 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2008,117(4):581-594
In flowering plants, double fertilization occurs when the egg cell and the central cell are each fertilized by one sperm cell. In maize, some lines produce pollen capable of inducing in situ gynogenesis thereby leading to maternal haploids that originate exclusively from the female plant. In this paper, we present a genetic analysis of in situ gynogenesis in maize. Using a cross between non-inducing and inducing lines, we identified a major locus on maize chromosome 1 controlling in situ gynogenesis (ggi1, for gynogenesis inducer 1). Fine mapping of this locus was performed, and BAC physical contigs spanning the locus were identified using the rice genome as anchor. Genetic component analysis showed that (a) a segregation distortion against the inducer parent was present at this locus, (b) segregation resulted only from male deficiency and (c) there was a correlation between the rate of segregation distortion and the level of gynogenetic induction. In addition, our results showed that the genotype of the pollen determined its capacity to induce the formation of a haploid female embryo, indicating gametophytic expression of the character with incomplete penetrance. We propose the occurrence of a gametophytic-specific process which leads to segregation distortion at the ggi1 locus associated with gynogenetic induction with incomplete penetrance. 相似文献
13.
Molecular modelling of the GIR1 branching ribozyme gives new insight into evolution of structurally related ribozymes
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Twin-ribozyme introns contain a branching ribozyme (GIR1) followed by a homing endonuclease (HE) encoding sequence embedded in a peripheral domain of a group I splicing ribozyme (GIR2). GIR1 catalyses the formation of a lariat with 3 nt in the loop, which caps the HE mRNA. GIR1 is structurally related to group I ribozymes raising the question about how two closely related ribozymes can carry out very different reactions. Modelling of GIR1 based on new biochemical and mutational data shows an extended substrate domain containing a GoU pair distinct from the nucleophilic residue that dock onto a catalytic core showing a different topology from that of group I ribozymes. The differences include a core J8/7 region that has been reduced and is complemented by residues from the pre-lariat fold. These findings provide the basis for an evolutionary mechanism that accounts for the change from group I splicing ribozyme to the branching GIR1 architecture. Such an evolutionary mechanism can be applied to other large RNAs such as the ribonuclease P. 相似文献
14.
A new continuous line of goldfish somatic cells, designated SJU-1 has been continuously subcultured over a 39-month period. Best growth was obtained at 20°C over a pH range of 6.8–7.2. The minimal and optimal seed inocula, in terms of per cent cell increase, were determined to be 1.1 × 106 and 2.5 × 106 , respectively. The susceptibility of the SJU-1 line to infectious pancreatic necrosis virus offers an available assay system for goldfish in vivo and goldfish cells in vitro interferon studies. Chromosomal analyses of the line were also carried out. 相似文献
15.
The range of genetic variation of spontaneous chromosome doubling frequency of maize haploid plantlets derived from in vitro
anther culture was evaluated. When regeneration is obtained by direct embryo-genesis, bypassing the callus phase, it appears
that the frequency of spontaneous doubling may exceed 40 of the regenerated plantlets. This high frequency may be one consequence
of the use of doubled haploid lines derived from anther culture and spontaneous chromosome doubling. We also report an increase,
by more than 50, of the productivity of diploid fertile regenerated plantlets produced by colchicine supplemented medium during
the cold shock pretreatment of the microspores inside the anthers. Optimization of the treatments and the anther culture procedure
are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
17.
Caroline Tassy Anne Partier Michel Beckert Catherine Feuillet Pierre Barret 《Plant Cell, Tissue and Organ Culture》2014,119(1):171-181
The feasibility of map-based cloning in wheat has been demonstrated recently, opening new perspectives for a better understanding of wheat plant biology and for accelerating wheat improvement in the coming decades. To validate the function of candidate genes, an efficient transformation system is needed. Here, we have performed two methods for wheat transformation using particle bombardment that ensures the production of transgenic plants with simple integration patterns for research purposes and stable transgene expression for accurate and rapid validation of gene function. To establish this method, we used the bar and pmi selectable genes either as part of whole plasmids, gene cassettes (obtained by PCR or purified on agarose gels), or as dephosphorylated cassettes. The analysis of about 300 transgenic plants showed that the use of gene cassettes or dephosphorylated gene cassettes leads to a majority (50–60 %) of simple integration events. This is significantly higher than the number of simple events obtained with whole plasmids (9–25 %). Moreover, the decrease of the quantity of DNA from 500 to 5 ng/µl for PCR-amplified cassettes used for transformation increased the number of single integration events. The transformation efficiency remained stable at 2.5 %, and a higher number of plants expressing the transgenes were obtained with the dephosphorylated cassette. No correlation was observed between the complexity of the events and stability of expression of the transgene, suggesting that plasmid sequences could be involved on transgene silencing. The inheritability of the transgene was demonstrated in T1 and T2 generations. These results show that biolistic transformation of dephosphorylated gene cassettes provides an easy and efficient route to produce backbone vector-free transgenic wheat carrying and expressing intact and single transgenes. 相似文献
18.
Significance of nucleotide sequence alignments: a method for random sequence permutation that preserves dinucleotide and codon usage 总被引:10,自引:0,他引:10
The similarity of two nucleotide sequences is often expressed in terms of
evolutionary distance, a measure of the amount of change needed to
transform one sequence into the other. Given two sequences with a small
distance between them, can their similarity be explained by their base
composition alone? The nucleotide order of these sequences contributes to
their similarity if the distance is much smaller than their average
permutation distance, which is obtained by calculating the distances for
many random permutations of these sequences. To determine whether their
similarity can be explained by their dinucleotide and codon usage, random
sequences must be chosen from the set of permuted sequences that preserve
dinucleotide and codon usage. The problem of choosing random dinucleotide
and codon-preserving permutations can be expressed in the language of graph
theory as the problem of generating random Eulerian walks on a directed
multigraph. An efficient algorithm for generating such walks is described.
This algorithm can be used to choose random sequence permutations that
preserve (1) dinucleotide usage, (2) dinucleotide and trinucleotide usage,
or (3) dinucleotide and codon usage. For example, the similarity of two
60-nucleotide DNA segments from the human beta-1 interferon gene
(nucleotides 196-255 and 499-558) is not just the result of their nonrandom
dinucleotide and codon usage.
相似文献
19.
Human skin was fixed in Davidson's solution (95% alcohol, 35; formalin, 20; glacial acetic acid, 10; and distilled water, 35—parts by volume) and sections prepared through paraffin embedding in the usual manner. Stock stains were: I(BS)—Biebrich scarlet, 1 gm in 100 ml of 50% alcohol to which 0.3 gm of phosphotungstic acid and 5 ml of glacial acetic acid were added—and II(FG)—fast green, 0.5 gm in 85 ml of 50% alcohol to which 0.3 gm of phosphotungstic acid, 0.3 gm of phosphomolybdic acid, and 15 ml of glacial acetic acid were added. Experimental staining solutions were prepared in the following proportions of stock BS to stock FG—1:1, 2:1, 3:1, 1:2 and 1:3. Sections were brought to 50% alcohol and stained for 15, 20, 25 and 30 min in each of the five BS-FG mixtures, rinsed in 50% alcohol, then dehydrated in 70%, 95%, and absolute alcohol, 2 min each; cleared in xylene, and covered in balsam. The 2:1 (optimum proportion) combination of BS with FG, acting for 20 min, yielded 97% sex chromatin-positive nuclei in female material. If sections were stained in stock solution BS for 2 min, they could be differentiated by a 20 min treatment in the mordanting component of stock FG (without dye) to give a one-color stain. Such stains gave about the same percentage of sex chromatin-positive nuclei as those obtained by the regular two-color procedure. These modifications are simpler, more rapid, and yield results comparable to previously employed techniques. 相似文献
20.
Optimization of maize microspore isolation and culture conditions for reliable plant regeneration 总被引:1,自引:0,他引:1
Summary The effects of different factors were investigated in the process of isolated microspore culture of Zea mays L., Using donor plants grown in standard conditions and an efficient isolation technology, homogeneous populations of viable microspores at specific developmental stages were obtained and tested in culture. The cytological evolution of the microspores during the first week of culture was monitored using a DNA-specific fluorochrome. It was found that developmental stages of microspores, number of days of pretreatment at 7°C of the tassel, and culture density greatly influenced the number of microspore-derived embryos. Optimal conditions required for embryo and plant production are described.Abbreviations ISO
isolation medium
- MS
Murashige and Skoog
- Na2EDTA
ethylene diaminetetraacetic aciddisodium salt
- AS
androgenic structures
- CFA
correspondence factorial analysis
- FDA
fluorescein diacetate
- IM
induced microspores 相似文献