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21.
Inbred lines of white clover (Trifolium repens L.) have been produced utilising the rare self-fertility (Sf) allele. Twenty-two
lines of four distinct groups have been maintained through five generations of selfing by single seed descent. Fourteen lines
were used in crosses to produce F1s. Both parents and hybrids were analysed for a range of morphological characters. Positive heterosis for dry matter production
was observed in half the hybrids. No other trait showed significant heterosis. The degree of heterosis appears to be related
to the extent of variation in morphological characters between the parental lines, some combinations of lines yielding heterotic
hybrids in all cases, others in none. The majority of the F1 hybrids are superior in terms of dry matter production to eight control varieties.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
22.
Summary A total of 749 genotypes from a number of white clover (trifolium repens L.) cultivars and populations, many collected from dryland areas, were cloned and grown in field titles. Several morphological characters, including leaf size, number and diameter of large nodal roots (taproots), and proportion of root weight that was classified as taproot were measured. There was large variation between lines and genotypes for all characters measured, and differences between genotypes within lines are also reported. Broad sense heritability estimates were higher (>0.5) for leaflet width, petiole length and stolon diameter, than for all root character heritability estimates which were between 0.2 and 0.4. 相似文献
23.
E. Arseniuk 《Plant Breeding》1989,103(4):310-318
The effect of induced autotetraploidy on the response of red clover to Sclerotinia clover rot (SCR) was studied under laboratory, glasshouse and field conditions. To assess the response in the laboratory, the detached leaf technique was employed, whereas in the glasshouse and in the field, 6—14 weeks old seedlings and adult plants, respectively, were artificially inoculated with the pathogen grain inoculum. The results of the studies showed that great genotypic variability occurs within diploid (2×)and tetraploid (4×)red clover in response to that disease. Generally, tetraploid red clover, in comparison to diploid, is more resistant to SCR. The laboratory, glasshouse and field experiments showed that the effect of induced autotetraploidy on SCR resistance is positive. The hardening of plant with light and temperature enlarged the differences in reponse to SCR between ploidy levels, family pairs and individual strains with every testing method. Other factors, like plant age and flowering time, influencing red clover response to SCR are also discussed. 相似文献
24.
Summary Seedlings of Trifolium repens showed considerable variation with regard to the morphology and growth of their calli, and their ability for in vitro differentiation of shoots. One of the lines selected for regeneration in primary callus cultures also showed shoot formation from protoplasts. Somatic embryogenesis in callus cultures of T. pratense and T. arvense occurred only in selected seedling lines. This paper highlights the importance of screening a large number of plants within a cultivar of outbreeding species to achieve reproducible plant regeneration from tissue culture. 相似文献
25.
Growth of full-sib families of an F1 interspecific hybrid between Trifolium ambiguum M.Bieb and T. repens L, and two generations of backcross hybrids (BC1F2 and BC2F1) with T. repens as the recurrent parent, were compared to their parental species. Plants were grown in a N-free medium and inoculated with
Rhizobium leguminosarum biovar trifolii rhizobia effective on T. ambiguum or T. repens. Hybridisation produced progeny that nodulated with rhizobia from either T. ambiguum or T. repens, but plant growth varied. Mean weights of T. repens and
hybrids, particularly F1 and BC1F2, were higher when inoculated with a mixture of strains isolated from field grown T. repens than with the New Zealand inoculant strain for T. repens. When inoculated with the mix of rhizobia from T. repens, mean weights were 242, 189, 132, 125, and 100 mg/plant for T. repens, BC2F1, BC1F2, F1 and T. ambiguum, respectively. However, although the mean weight of BC2F1 lines was significantly less than T. repens, there was considerable variation in individual full-sib families indicating the potential to select within
BC2F1 hybrids for high plant growth/symbiotic nitrogen fixation. The weight of T. ambiguumplants inoculated with the New Zealand inoculant strain for hexaploid T. ambiguum was similar to T. repens inoculated with the mix of rhizobia from T. repens (253 and 242 mg/plant, respectively). Mean fresh weights of F1 hybrid plants were similar when inoculated with rhizobia for T. ambiguum or T. repens (125 and 130 mg/plant, respectively). However, weight of T. repens, BC1F2 and BC2F1 hybrids inoculated with rhizobia for T. ambiguum were all less than 90 mg/plant. There was a
significant relationship between plant fresh weight and ethylene production. The results indicate that measuring weights of
inoculated plants growing in N-free media is a rapid initial method of screening a range of plant germplasm for plant growth/symbiotic
nitrogen fixation rates.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
26.
A.H. Marshall T.P.T. Michaelson-Yeates M.T. Abberton A. Williams H.G. Powell 《Euphytica》2002,126(2):195-201
Interspecific hybridisation with Trifolium nigrescens Viv. is a possible strategy to improve the reproductive potential of white clover (Trifolium repens L.). Following the development of a fertile F1 hybrid, three generations of backcrossing have been carried out usingT. repens as the recurrent parent. Vegetative characteristics, stolon growth and seed yield components of the backcross (BC) 2 and
3 generations, as well as the parental species were measured on spaced plants grown in the field. Leaf size and plant spread
of the BC2 and BC3 generations were less than T. repens but there was no difference in plant fresh weight. Numbers of inflorescences per plant and florets per inflorescence of the
backcrosses were greater than T. repens however this was not reflected indifferences in seed yield per plant asT. repens had more seeds per floret and per plant than the backcrosses. Differences in stolon length, the proportion of flowering nodes
and the pattern of axillary bud development were observed between T. repens and the backcrosses. Significant variation among the BC 3 generation for vegetative and reproductive traits was observed.
Individual plants among the BC 3 generation were identified that combine high forage yield, substantial inflorescence production
and good fertility, and these will form the basis of further selection.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
27.
Summary A collection of subterranean clover lines singled out from populations of the species Trifolium brachycalycinum and T. subterraneum collected in Sicily, Italy, was examined at two localities for flowering time and at one locality for oestrogen content and seed yield. The structure and variation of the populations of the two species were compared. The relationship between flowering time of the populations and some environmental features of their collection sites was examined to assess whether the maturity requirements of the two species were similar and to frame selection models focused on developing varieties of appropriate maturity. Populations of T. subterraneum were, on average, more complex than those of T. brachycalycinum, being characterized by higher number of lines per population and greater intra-population variation for flowering time, oestrogen content and seed yield. Furthermore, populations of T. subterraneum were, on average, about 15 days earlier than sympatric populations of T. brachycalycinum. Both the greater variation and the relative earliness of T. subterraneum occurred irrespective of the environments of origin of the populations. Inferences are drawn on the adaptive advantages that such features confer to T. subterraneum. Mean flowering time of the populations increased on increasing annual rainfall and altitude of the collection sites. However, the changes in maturity appeared almost exclusively related to variations in rainfall in T. subterraneum, while in T. brachycalycinum the effect of altitude was greater and that of rainfall less marked than in the former species. 相似文献
28.
Paolo Annicchiarico 《Euphytica》1993,71(1-2):131-141
Summary A set of Ladino white clover ecotypes including the last available landraces and some natural populations collected from old permanent meadows, together with some white clover varieties of various origins, were evaluated as monocultures for dry matter (DM) and seed yield assessed in separate field experiments. Other agronomic traits were also recorded. The best performing variety, Espanso, was significantly outyielded by some ecotypes for DM and seed production. Compared to landraces, natural populations yielded on average far less seed but as much DM and tended towards higher persistence indicating that domestication of the native Ladino at the farm level only improved seed yield of the crop. Natural populations showed, besides lower values of most seed yield components, a distinct canopy architecture characterized by smaller leaves, longer internodes and denser stolons. Seed weight proved the best character discriminating between the two ecotype groups. Significant variation for most traits was found both among landraces, in which it was mostly relatable to differences among provenances, and among natural populations. The relations between the main multivariate patterns of phenotypic variation and a set of environment collecting variables suggested that evolutive adaptation to different agronomic practices was a major determinant of the overall variation found in landraces. Evidence is provided that a relevant part of the variation observed among ecotypes for some important traits could be genetic.Abbreviations DM
dry matter
- DMY
dry matter yield
- NRH
number of ripe heads
- NFH
number of florets per head
- PL
petiole length
- LS
leaf size
- IL
internode length
- NS
number of stolons
- PRO
protein content
- SY
seed yield
- TSW
thousand seed weight
- NSF
number of seeds per floret
- PCA
principal components analysis
- PC
principal component 相似文献
29.
K. H. Chorlton I. D. Thomas D. W. Bowen Z. Bulínska-Radmoska M. Gorski 《Genetic Resources and Crop Evolution》1996,43(1):69-77
Summary The Plant Genetic Resources Unit (PGRU) of the Institute of Grassland and Environmental Research, Welsh Plant Breeding Station (IGER, WPBS), UK, and the Plant Genetic Resources Section of the Plant Breeding and Acclimatization Institute (PBAI), Poland, carried out a joint collecting expedition in Poland between 25 August and 7 September 1990. The expedition was unique in that it was the first time that vegetative sampling had been applied to the perennial forage grass and legume populations of south east Poland. The expedition focused on seminatural vegetation in agriculturally managed situations and detailed collection site data on management systems was obtained from landowners.Samples were collected from 62 sites. Vegetative collections of Lolium spp. (37 populations) and Trifolium spp. (56 populations), and seed collections of Festuca spp. (32 populations) were made by the IGER team (Table 2). The PBAI team made 59 separate seed collections, mainly of Leguminosae.The expedition covered four geographical subregions of south east Poland. (See Fig. 1). These were the Nizina Mazowiecka south of Warszawa, the Wyzyna Malopolska with the town of Kielce at its centre and the Beskidy Zachodnie and Beskidy Wschodnie regions of the Carpathian mountains.A diverse range of habitats was sampled covering a broad range of altitude agricultural management systems and ecological conditions. Polish agriculture is faced with the problems of a rapid orientation to a market economy and it is likely that the diverse range of habitats encoutered will be reduced as agricultural practices change. This will lead to genetic erosion of the unique forage grass and legume populations to be found in Poland.Abbreviations ECP/GR
European Co-operative Programme on Crop Genetic Resources
- IGER
Institute of Grassland and Environmental Research
- PBAI
Plant Breeding and Acclimatization Institute
- PGRU
Plant Genetic Resources Unit
- WPBS
Welsh Plant Breeding Station 相似文献
30.
Fernanda Bortolini Miguel Dall’Agnol Maria Teresa Schifino-Wittmann 《Genetic Resources and Crop Evolution》2006,53(5):1081-1087
White clover is one of the most important forage legume species worldwide, playing an important role in Southern Brazil temperate
cultivated pastures. This work was aimed to characterize the genetic variability of the USDA white clover core collection
formed by 78 accessions representing 50 countries, together with two very well known cultivars (Huia and Ladino Regal), using
RAPD (Random Amplified Polymorphic DNA) markers to produce genetic fingerprints. There were used DNA bulks formed by the extraction
and mixture of 20 random individuals from each accession. Twenty four primers were used, which revealed from 3 to 29 bands,
forming a total of 371 polymorphic bans and only one monomorphic, ranging from 50 to 3098 bp. The results showed a genetic
similarity among the accessions, ranging from 0.18 to 0.58 (Jaccard’s index), with an average of 0.24, allowing the identification
of each individual accession using just three primers. The results also showed a large genetic variability within the white
clover core collection, probably due to its reproduction mode and ploidy level, which could be used in plant breeding program. 相似文献