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991.
Can cultivars from participatory plant breeding improve seed provision to small-scale farmers? 总被引:1,自引:0,他引:1
Seed provision for small-scale farmers deals with multiple constraints. These include, on the supply side, high seed production
costs and poor adaptedness of the cultivars, and on the demand side, anticyclical demand and low and variable sales. Approaches
to improve seed provision to this sector of farmers have so far not been very successful. This paper discusses how well-adapted
cultivars developed through participatory plant breeding (PPB) initiatives create new opportunities for production and distribution
of quality seed. It reviews supply and demand-side issues, based on research and experiences with seed production. Given better
adaptation of PPB-cultivars, the diffusion of seed of PPB initiatives should not be a major bottleneck. But constraints in
the provision of quality seed from cultivars that are commonly used remain and need to be addressed. Major points of attention
are cost-effective seed production and distribution, high information linked transaction costs, and appropriate seed production
technology. Research on these issues is needed to understand farmers’ seed demand. At the same time, these issues need to
be taken into account in new seed production initiatives that apply integrated approaches. Long term commitment by farmers
to produce, distribute and use seeds is a condition. Even if seed production is not economically sustainable at household
or organization level, farmer-based seed systems generate benefits to society as a whole that justify long term public investment
to maintain them. 相似文献
992.
993.
Some iodoamino acids have been separated and determined by high pressure liquid chromatography on octadecylsilane reverse phase packing with a mobile phase consisting of methanol, potassium phosphate monobasic, and orthophosphoric acid at 44 degrees C. The method separates and quantitates mixtures of 3,5-diiodothyronine, liothyronine, isoliothyronine, and levothyroxine. The procedure provides an accurate, sensitive, and rapid estimation of decomposition and/or impurities in standards in approximately 30 min, at the less than 75 pmole level, using an ultraviolet detector at 254 nm. 相似文献
994.
995.
Influence of dietary protein level on body composition and energy expenditure in calorically restricted overweight cats 下载免费PDF全文
X. des Courtis A. Wei P. H. Kass A. J. Fascetti J. L. Graham P. J. Havel J. J. Ramsey 《Journal of animal physiology and animal nutrition》2015,99(3):474-482
High‐protein (HP) diets help prevent loss of lean mass in calorie‐restricted (CR) cats. However, it is not entirely known whether these diets also induce changes of energy expenditure during periods of CR. To investigate this issue, sixteen overweight cats were fed either a high‐protein [(HP), 54.2% of metabolizable energy (ME)] or a moderate‐protein [(MP), 31.5% of ME] diet at 70% of their maintenance energy intakes for 8 weeks, and energy expenditure, energy intake, body weight and composition, and serum metabolites and hormones were measured. While both groups of cats lost weight at a similar rate, only cats eating the HP diet maintained lean mass during weight loss. Indirect respiration calorimetry measurements revealed that both total and resting energy expenditure (kcal/d) significantly decreased during weight loss for both treatment groups. However, only cats eating the MP diet exhibited significant decreases of total and resting energy expenditures after energy expenditure was normalized for body weight or lean mass. Results from this study suggest that in addition to sparing the loss of lean mass, feeding HP diets to overweight cats in restricted amounts may be beneficial for preventing or minimizing decreases of mass‐adjusted energy expenditure during weight loss. 相似文献
996.
H. L. Ko P. R. Campbell M. P. Jobin-Décor K. L. Eccleston M. W. Graham M. K. Smith 《Euphytica》2006,150(3):387-395
Summary A transformation technique for the introduction of transgenes to control blackheart by particle bombardment has been developed for pineapple cv. Smooth Cayenne. Leaf callus cultures capable of high frequency organogenesis with a short regeneration time were used as explant material. Gus and gfp reporter genes were used to observe and determine transient and stable expression. The ppo gene, isolated from pineapple, was introduced to control blackheart. Co-transformation occurred with constructs containing the nptII gene conferring geneticin resistance. We have recovered 15 independent transgenic gus and gfp lines each from 8 separate experiments and 22 ppo lines from 11 experiments. Gus, gfp, ppo and nptII positive plants have been regenerated, which have been shown by Southern blot analysis to be stable transgenics containing multiple copies of the introduced genes. These results show that biolistic gene delivery in pineapple can be successfully achieved at an acceptable efficiency of 0.21–1.5% for genetic improvement of ’Smooth Cayenne’, the industry standard throughout the world. 相似文献
997.
H. L. Ko D. C. Cowan R. J. Henry G. C. Graham A. B. Blakeney L. G. Lewin 《Euphytica》1994,80(3):179-189
Summary The genetic relationships between rice varieties were analysed by using the polymerase chain reaction (PCR), with arbitrary oligonucleotide primers in the random amplified polymorphic DNA (RAPD) method. PCR with 22 arbitrary primers applied to 37 varieties produced 144 useful markers, of which 67% were polymorphic. Thus, with selected primers sufficient polymorphism could be detected to allow identification of individual varieties. Visual examination of electrophoresis gels and analysis of banding patterns confirmed that commercial Australian and USA lines and their relatives were very closely related, with similarity indices of 88–97%. Three varieties originating from more distant geographical centres were easily distinguished, producing variety-specific amplification profiles and expressing a lower similarity index of 80% to all other varieties tested. PCR offers a potentially simple, rapid and reliable method for rice genotype identification and recognition of lines that could contribute genetic diversity to new commercial varieties.Abbreviations PCR
Polymerase Chain Reaction
- RAPD
Random Amplified Polymorphic DNA 相似文献
998.
Graham J. King F. H. Alston I. Battle E. Chevreau C. Gessler J. Janse P. Lindhout A. G. Manganaris S. Sansavini H. Schmidt K. Tobutt 《Euphytica》1991,56(1):89-94
Summary A recently initiated collaborative project involving apple breeders in seven European countries is described. The objective is to improve the European apple crop by molecular-aided breeding to increase efficency and reduce the time-scale in breeding for resistance, tree habit and fruit quality. The strategy adopted provides a model for similar studies in fruit, forest and other woody species. The project is based on progenies from a small number of crosses involving many important agronomic genes. Replication of these reference progenies by vegetative propagation will enable studies to be carried out simultaneously in each country. By developing a range of molecular markers, including isozymes, RFLPs and sequence-tagged DNA probes, an integrated molecular map is being constructed for use in a wide range of breeding and genetic studies. Construction of a database recording many mapped molecular markers will enable efficient exploitation of data in future genetic, breeding and physiological studies of apple. Aspects of the adopted strategy, techniques and management are discussed in the context of mapping genes in perennial crop genomes. 相似文献
999.
The New Zealand hop breeding programme is based solely on the development of seedless triploid cultivars. This relies on the
use of tetraploid parents. While a sexually derived tetraploid parents have been used successfully, sexually derived tetraploids
offer a useful alternative. They may have a higher level of heterozygosity and are easier to obtain. Methods for the identification
of tetraploids from seedling populations by flow cytometry are described. Two studies were conducted; one on field-grown plants,
the other on plants grown in a glasshouse. Approximately 15%of seedlings in the two studies were identified as tetraploids
(2n = 4x = 40). Between 70 and 80% were identified as either diploid (2n =2x = 20) or triploid (2n = 3x = 30). Remaining plants were haploid, pentaploid or probably aneuploid. Within triploid and tetraploid populations from 40to
50% of seedlings were female, 30 to40% were monoecious, with the remainder being males and non-flowering plants. Sexually
derived tetraploid parents have been used successfully in the breeding programme, from which several promising triploid selections
have subsequently been made.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
1000.
H. Khabaz-Saberi R. D. Graham M. A. Pallotta A. J. Rathjen K. J. Williams 《Plant Breeding》2002,121(3):224-227
Manganese (Mn) deficiency is a major constraint of alkaline soils around the world, particularly for cultivation of durum wheat, which is more intolerant of low Mn levels than either common wheat or barley. Genetic variation for Mn efficiency exists in the current germplasm of durum wheat. Several restriction fragment length polymorphisms (RFLPs) previously shown to be linked to the Mel1 locus for Mn efficiency on chromosome 4HS of barley were tested on 88 selected F2 plants of the durum cross, ‘Stojocri 2’ (Mn efficient) בHazar’ (Mn inefficient). The Mel1‐linked RFLP marker Xcdo583a was closely linked to the trait and explained over 42% of the total variation for Mn efficiency in the ‘Stojocri 2’/‘Hazar’ F2 progeny. This marker has the potential to provide a valuable tool for the marker‐assisted selection of Mn‐efficient durum progeny derived from crosses with ‘Stojocri 2’. 相似文献