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61.
Comparative flow cytometric estimation of nuclear DNA content in oil palm (Elaeis guineensis Jacq) tissue cultures and seed-derived plants 总被引:1,自引:0,他引:1
Flow cytometric analysis performed on two different crosses of dura×pisifera oil palm gave an accurate estimation of nuclear DNA content. The genome size of Elaeis guineensis was found to be 2C=3.76±0.09 pg and therefore ca. 3.4×109 bp. Embryogenic calli and plants showed the same ploidy level, but the measured 2C DNA values differed significantly. No
variation in the ploidy level between three different types of calli originating from foliar explants, namely nodular compact
callus, fast-growing callus and friable callus was observed. Since fast-growing callus (FGC), already identified as a source
of `mantled' phenotype variants, did not show any difference in their ploidy level, these results are consistent with the
hypothesis of an epigenetic origin for this type of somaclonal variant.
Received: 17 February 1997 / Revision received: 13 May 1997 / Accepted: 22 May 1997 相似文献
62.
Kathelyne Craenen R. Ortiz 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(3):497-505
Use of resistant host genotypes is an important component of an integrated approach to control black sigatoka, a disease
caused by the fungus Mycosphaerella fijiensis Morelet. The objective of the present research was to determine the role of the major gene for black sigatoka resistance
(bs
1
) in the host response to this disease. Euploid hybrids with a known genotype for the bs
1
locus were derived from triploid-diploid crosses of two French plantains and a diploid wild banana, and were assessed for
their host response to black sigatoka in plant and ratoon crops in the humid forest zone of Nigeria. Host response was determined
at flowering by recording the number of standing leaves, the youngest leaf with symptoms, the youngest leaf spotted, the total
leaf area attacked by black sigatoka, and an index of the leaves spotted. An analysis of frequency distribution in each segregating
population showed that almost all the traits displayed a normal distribution across ploidy level. This suggests that additive
gene action plays an important role in the host-plant response to the fungus. Heritability, repeatibility, and intraclass
correlations were calculated. The environment and the genotype-by-environment interaction significantly affected the host
response to black sigatoka, which explains the low repeatibility of all traits. The intrafamily variation was larger than
the interfamily variation, and most of the genetic variation in each family depended on the individual genotypes, regardless
of their ploidy. The additive effect of, and the intralocus interaction at, the bs
1
locus on host response to black sigatoka were established by a one-way analysis of variance and regression analyses. Intralocus
interaction in the bs
1
locus apparently regulates the appearance of symptoms on the leaf surface, whereas the additive effect and the intralocus
interaction of the bs
1
locus affect disease development in the host plant. Therefore, the gene action(s) at the bs
1
locus may provide durable resistance to black sigatoka by slowing down disease development in the host plant.
Received: 18 September 1996 / Accepted: 4 April 1997 相似文献
63.
G. Barcaccia A. Mazzucato A. Belardinelli M. Pezzotti S. Lucretti M. Falcinelli 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(4):516-524
Moving gene(s) responsible for the apomictic trait into crop plants that naturally reproduce through a sexual process would
open up new areas in plant breeding and agricultural systems. Kentucky bluegrass (Poa pratensis L.) is one of the most important forage and turf grasses in temperate climates. It reproduces through facultative aposporous
parthenogenesis, but the reproductive behaviour ranges naturally from nearly obligate apomixis to complete sexuality. In addition
to apomictic reproduction, sexual hybridization may take place. Selfing may also occur, and occasionally reduced egg cells
may develop through parthenogenesis generating (poly)haploids. The inheritance of parental genomes was assessed in Kentucky
bluegrass progenies by employing RAPD markers in combination with flow cytometry (FCM). Nine progenies from different crosses
carried out between completely sexual and highly apomictic genotypes were evaluated in order to probe the reproductive behaviour
of the mother plants and to distinguish the different classes of aberrant plants. Not only were maternals and balanced BII hybrids recorded, but so were (poly)triploid BIII hybrids, selfs, and (poly)haploids. The application of these techniques demonstrated that FCM analysis accurately distinguishes
the n, 2n, and 3n ploidy levels of progenies, and that RAPD markers unequivocally recognize progenies of apomictic and hybrid
origin. The occurrence of aneusomaty was documented in one of the selected sexual genotypes, whose crossed progeny plants
manifested two distinct classes of ploidy. The nomenclature BI was adopted to refer to hybrids with a hypodiploid nuclear condition. On the whole, the FCM analysis confirmed most of the
RAPD data. The combined evaluation of DNA markers and DNA contents proved to be an efficient screening tool for scoring maternal
plants, assessing the genetic origin of aberrant plants, and quantifying the inheritance of parental genomes in Kentucky bluegrass.
Hybrid populations from sexual×apomictic matings that segregate for the mode of reproduction represent a valuable basis for
attempting to identify molecular markers linked to the apomixis gene(s).
Received: 11 November 1996/Accepted: 22 November 1996 相似文献
64.
Effect of ploidy and homozygosity on transgene expression in primary tobacco transformants and their androgenetic progenies 总被引:5,自引:0,他引:5
A. Beaujean R. S. Sangwan M. Hodges B. S. Sangwan-Norreel 《Molecular & general genetics : MGG》1998,260(4):362-371
Expression of a transgene is rarely analysed in the androgenetic progenies of the transgenic plants. Here, we report differential
transgene expression in androgenetic haploid and doubled haploid (DH) tobacco plants as compared to the diploid parental lines,
thus demonstrating a gene dosage effect. Using Agrobacterium-mediated transformation, and bacterial reporter genes encoding neomycin phosphotransferase (nptII) and β-glucuronidase (uidA/ GUS), driven respectively by the mas 1′ and mas 2′ promoters, we have generated more than 150 independent transgenic (R0) Nicotiana tabacum plants containing one or more T-DNA copies. Transgene analyses of these R0, their selfed R1 lines and their corresponding haploid progenies showed an obvious position effect (site of T-DNA insertion on chromosome)
on uidA expression. However, transgene (GUS) expression levels were not proportional to transgene copy number. More than 150 haploids
and doubled haploids, induced by treatment with colchicine, were produced from 20 independent transgenic R0 plants containing single and multiple copies of the uidA gene. We observed that homozygous DH plants expressed GUS at approximately 2.9-fold the level of the corresponding parental
haploid plants. This increase in transgene expression may be attributed mainly to the increase (2-fold) in chromosome number.
Based on this observation, we suggest a strong link between chromosome number (ploidy dosage effect) and transgene expression.
In particular, we demonstrate the effect on its expression level of converting the transgene from the heterozygous (in R0 plants) to the homozygous (DH) state: e.g. an increase of 50% was observed in the homozygous DH as compared to the original
heterozygous diploid plants. We propose that ploidy coupled with homozygosity can result in a new type of gene activation,
creating differences in gene expression patterns.
Received: 27 April 1998 / Accepted: 12 August 1998 相似文献
65.
Histochemical identification of primordial germ cells in diandric and digynic triploid mouse embryos
Diandric and digynic triploid mouse embryos were isolated in the morning on day 10 of gestation. The embryos were separated from their extraembryonic membranes, and the latter were analysed cytogenetically by G-banding to establish the ploidy and sex chromosome constitution of these embryos. The diandric triploid embryos were produced by the technique of nuclear micromanipulation. Females were mated with male mice with a morphologically distinguishable "marker" chromosome to confirm the diandric status of these embryos. Digynic triploid and normal diploid embryos were isolated from LT/Sv strain females. These females spontaneously ovulate both primary and secondary oocytes, which are fertilisable and give rise to digynic triploid and normal diploid embryos, respectively. All the embryos were serially sectioned and processed in order to demonstrate the presence of alkaline phosphatase enzyme activity. This histochemical technique allowed primordial germ cells to be readily recognised, due to their characteristic location, cellular morphology, and staining appearance. Primordial germ cells were found in all the embryos studied, being located within the visceral yolk sac, at the base of the allantois, and/or in association with the wall or mesentery of the hindgut. The total number of germ cells present was established in nine diandric triploids and in five digynic triploids. The findings presented here represent the first demonstration that primordial germ cells can differentiate in either diandric or digynic triploid mammalian embryos. 相似文献
66.
S. R. Rivard M. Cappadocia G. Vincent N. Brisson B. S. Landry 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,78(1):49-56
Summary Green mesophyll protoplasts of the dihaploid potato line 1982 (Solanum tuberosum L.) were fused with herbicide-bleached mesophyll protoplasts of the dihaploid potato line 679 using a polyethylene glycol protocol. Heterokaryons were identified under a fluorescence microscope using the dual fluorescence of carboxyfluorescein-stained, herbicide-bleached protoplasts and the autofluorescence of green mesophyll protoplasts. About 20% of the protoplasts survived the fusion treatment, and the fusion frequency was 3%–4%. Unfused and fused protoplasts were mass cultured for 6 weeks after which vigorously growing calli were selected and transferred to shoot regeneration medium. Somatic hybrids were identified by a combination of five isozyme markers, and the ploidy level was determined by flow cytometry. Out of 15 calli that regenerated shoots, 6 plants derived from 2 different calli were identified as hexaploid somatic hybrids, while one morphologically deviant plant from a third callus was identified as a mixoploid that had lost some enzyme markers after 4 months of culturing. 相似文献
67.
Summary
Vicia faba callus line (VFS 1), isolated from expiants of immature embryo, grew satisfactorily onMurashige andSkoog complete medium with 1.38 M 2,4-D, or with 0.92 M 2,4-D to which 1.0 M kinetin was added. It also grew well on the B 5 modified medium containing 2.3 M 2,4-D and 25.0 M kinetin. On the last of these media the cultures grew more uniformly and without necrosis. They also showed diminishing variation in polyploidy in favour of diploids and corresponding aneuploids (hypodiploids).After being cultured for nearly three years on MS containing 1.38 M 2,4-D, 8–33% of cultures of VFS 1 were able to regenerate roots when transferred to either MS half strength with 5.37 M NAA, or to a medium without 2,4-D, or else to media with the addition of kinetin only (in various concentrations). 相似文献
68.
The cellular amounts and cellular activities of acetyl CoA carboxylase (ACC; EC 6.4.1.2.) were determined in the first leaves of diploid, tetraploid and hexaploid species of Triticum (wheat). Per leaf the ACC activities were very similar in T. monococcum (2 ), T. dicoccum (4 ) and T. aestivum (6 ). The ACC activity per chloroplast also showed little variation between species of different ploidy but since chloroplast number increases with ploidy, the ACC activities and ACC amounts per cell also increased with ploidy. These cellular increases in ACC amounts associated with increases in gene dosage were highly co-ordinated in the diploids T. monococcum and T. tauschii and their respective autotetraploids so the specific activity of ACC was highly conserved in these plants. The relevance of these findings to attempts to genetically manipulate lipid biosynthesis in chloroplasts is discussed.Abbreviation ACC
acetyl CoA carboxylase
We are very grateful to Dr. Kevin Pyke and Miss Jo Marrison for many helpful discussions and to Dr. Collin Law for the generous gift of seeds. 相似文献
69.
重楼属的细胞分类研究 总被引:5,自引:1,他引:4
本文报道5种重楼植物的核型:凌云重楼(P. cronquistii);南重楼(P. vietnamensis);金线重楼(P. delavayi);长柱重楼(P. forrestii);和平伐重楼(P. vaniotii)。讨论了重楼属植物的核型结构和倍性的变异,以及杂合性、多态性、B染色体等染色体的结构变异。并将重楼属植物的核型归纳成三个主要的基本类型。1. 4t型,基本核型为2n=2x=10=6m+4t,分布于南部热带亚热带的多叶重楼P. polyphylla等13种的核型属于这一类型;2.2st型,基本核型为2n=2x=10=6m+2st+2t,分布于北温带的P. verticilata等5种属于这一类型;3.4st型,核型为2n=2x=10=6m+4st,仅有巴山重楼P. bashanensis的核型属这一类型。每个类型中各个种之间在染色体的结构上又表现出一定的差异。根据植物的染色体核型的演化规律,对三个类型核型的演变作了探讨。 相似文献
70.
The taxonomic status ofEupatorium chinese var.oppositofolium andE. glehni (=E. chinense subsp.sachalinense) inE. chinense complex semsu Kitamura has long been controversial. In this paper, the degree of divergence between diploids of these two
taxa was examined by means of morphological studies including principal component analysis, the electrophoretic analysis of
esterase isozyme variation and observations on habitats. The data obtained through the examinations indicate these two taxa
are diverged enough to be recognized as distinct biological species. Since the polyploidE. chinense var.oppositifolium is more or less intermediate in morphology between the two diploid taxa, it is considered to have masked the distinction
between the two diploid taxa. Also, electrophoretic evidence suggests that polyploidE. chinense var.oppositifolium is not a hybrid or hybrid derivative withE. glehni as a parental species. Possible origin of polyploidE. chinense varoppositifolium is also discussed. 相似文献