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101.
通过对小麦育种的F1、F2育种材料的抗病性分析,结果表明:凡是用抗病品种做为亲本的组合,其F1代表现抗病的几率远较其它组合为高,在抗病亲本具有免疫的情况下,其组合大部分表现显性,且在以后世代分离出免疫植株的几率也大。F2代后代分离免疫与高抗植株的多少与亲本的抗病性有着密切的关系。亲本的免疫或抗病的能力越强,后代出现免疫植株或高抗类型的植株几率越大。 相似文献
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Loblolly pine (Pinus taeda) seedlings from 12 full-sib families obtained from a six-parent half diallel mating design were challenged in a greenhouse
using two basidiospore inocula of the fusiform rust fungus (Cronartium quercuum f.sp. fusiforme) at extremely high spore density. Each basidiospore inoculum originated from a mixed gall collection of aeciospores obtained
from field-infected trees. Assessments at 4.5 months after inoculation showed that rust disease levels were high for every
full-sib family and were typically above 90% for most full-sib families for both inocula. However, disease (% galled) for
family E by A progeny, even at 9 months post inoculation, was lower, around 75%. A genetic model for interaction of two pairs
of genes was proposed to explain the observed infection levels (% galled) in this diallel based on a gene-for-gene hypothesis.
The putative genotypes of host parents and virulence compositions of mixed inocula were postulated. A bulk-segregant analysis
approach based on phenotype (gall vs. no gall) was used to search for dominant molecular markers associated with the potential
resistance genes in the host parents. A few candidate marker polymorphisms were observed between the gall vs. no gall bulks;
however, none of the candidates appropriately co-segregated with phenotype when tested across the progeny set. An alternative
model involving recessive resistance controlled by a single locus was also considered, but as with the two gene model, no
markers to support the appropriateness of the recessive resistance model were observed. 相似文献
105.
Cultivated groundnut (Arachis hypogaea L.) is an agronomically and economically important oilseed crop grown extensively throughout the semi-arid tropics of Asia, Africa and Latin America. Rust (Puccinia arachidis) and late leaf spot (LLS, Phaseoisariopsis personata) are among the major diseases causing significant yield loss in groundnut. The development of varieties with high levels of resistance has been constrained by adaptation of disease isolates to resistance sources and incomplete resistance in resistant sources. Despite the wide range of morphological diversity observed in the cultivated groundnut gene pool, molecular marker analyses have thus far been unable to detect a parallel level of genetic diversity. However, the recent development of simple sequence repeat (SSR) markers presents new opportunities for molecular diversity analysis of cultivate groundnut. The current study was conducted to identify diverse disease resistant germplasm for the development of mapping populations and for their introduction into breeding programs. Twenty-three SSRs were screened across 22 groundnut genotypes with differing levels of resistance to rust and LLS. Overall, 135 alleles across 23 loci were observed in the 22 genotypes screened. Twelve of the 23 SSRs (52%) showed a high level of polymorphism, with PIC values ≥0.5. This is the first report detecting such high levels of genetic polymorphism in cultivated groundnut. Multi-dimensional scaling and cluster analyses revealed three well-separated groups of genotypes. Locus by locus AMOVA and Kruskal–Wallis one-way ANOVA identified candidate SSR loci that may be valuable for mapping rust and LLS resistance. The molecular diversity analysis presented here provides valuable information for groundnut breeders designing strategies for incorporating and pyramiding rust and late leaf spot resistances and for molecular biologists wishing to create recombinant inbred line populations to map these traits.E.S. Mace and D.T. Phong contributed equally to this work. 相似文献
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M. L. Helander 《Forest Pathology》1994,24(3):171-180
Effects of simulated acid rain and heavy metals on the occurrence of Melampsoridium betulinum in naturally infected mountain-birch trees and seedlings (Betula pubescens subsp. tortuosa) were studied in a subarctic area where background polution levels are low. The short term (2 years) effects of copper, nickel and sulphuric acid, and long term (8 years) effects of nitric- and sulphuric-acid deposition on birch-rust infection were determined. 相似文献
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109.
Aster albescens is a medicinal plant. The rust caused by Aecidium asterum is a new record in China and an important disease of A. albescens in Feng Tong-zhai national reservation area. The percentages of diseased plant and the diseased leaf reach 100 and 28% respectively when the disease is serious. The disease results in leaf spot and leaf cast. Tuberculina persicina is a natural hyperparasite of A. asterum and is firstly reported in the world. The hyperparasite attacks aecium of A. asterum and hinderes the release of aeciospores. The symptom of the rust and the morphological characteristics of A.asterum is reported. The hyperparasitism of A. asterum and the morphological characteristics of the Tuberculina persicina are also reported. 相似文献
110.
Cowpea landraces belonging to Vigna
unguiculata (L.) Walp. subsp. unguiculata cv.-gr. unguiculata and cv.-gr. sesquipedalis collected from part of the Deccan Plateau and West Coast of India were evaluated to (i) identify the diverse source(s) of
variation for improved characters like pods/peduncle and seed index (ii) study the response of landraces for adaptation to
drought and heat stress and (iii) understand the breeding value of a landrace in the genetic improvement of a popular cowpea
cultivar. Landraces were evaluated for various morphological characters, pods/peduncle, seed index and other economically
important agronomic traits, rust resistance and drought and heat tolerance in different years and environments. Landraces
were found as an important source of genetic variability for pods/plant, pods/peduncle, better pod filling ability (seed index),
grain yield/plant as well as drought and heat tolerance and rust resistance. Hybridization between C 152 (cv.) and DWDCC 016
(landrace) resulted in release of new variation not present in the two parents. Thus the landrace, DWDCC 016, can be utilized
to improve cultivated varieties by transferring to them the economically valuable traits like pods/peduncle and seed index
thereby enhancing realisation of sink potential and ultimately grain yield in a sustainable way. 相似文献