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81.
Distribution and accumulation of cassava brown streak viruses within infected cassava (Manihot esculenta) plants
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Cassava brown streak disease (CBSD), caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), ranks among the top seven biological threats to global food security. The disease poses a significant threat to cassava production in East and Central Africa (ECA). In Uganda, overall CBSD incidence increased by c. 20% since it re‐emerged in 2004, and the disease persistently reduces cassava yields and storage root qualities. The spread of CBSD has been studied spatially in fields in different agroecologies. However, within‐host distribution and accumulation of CBSV and UCBSV in naturally infected cassava plants is unknown. Therefore, within‐host CBSV and UCBSV distribution was studied to correlate CBSD symptoms with virus titre in organs of infected cassava. Leaf, stem and storage root samples, with and without symptoms, were collected from 10 genotypes of field‐grown cassava. Presence of CBSV and UCBSV was detected by RT‐PCR and virus levels determined by qRT‐PCR. CBSV was present in 100% of CBSD samples with symptoms, with 45·3% positive for presence of both CBSV and UCBSV. Tolerant cassava genotypes were infected with CBSV alone and accumulated higher titre in roots than in aerial organs. Susceptible genotypes were co‐infected with CBSV and UCBSV and exhibited variation in virus titre in each organ. Across genotypes, virus titre was lowest in the youngest leaves and highest in mature non‐senescing leaves. This information provides insight into the relationship between CBSV, UCBSV and their cassava host, and is valuable for CBSD resistance breeding, epidemiology studies and CBSD control. 相似文献
82.
BACKGROUND: Limiting the use of fungicides is due to become an important issue in managing Erysiphe necator (Schwein) Burrill infections in vineyards. The authors determined how three fungicides currently used by vine growers could be managed to control the early stages of an E. necator‐induced epidemic. RESULTS: Leaf‐disc bioassays and field experiments suggested that the protectant quinoxyfen induced minor disruption in E. necator development, but compounds with protectant and curative properties (tebuconazole and trifloxystrobin) caused significant, although different, disruption during E. necator‐induced epidemics. Bioassays showed that each of the antifungals were most effective at different stages of fungal development, tebuconazole before sporulation and trifloxystrobin after sporulation of the colonies. Results from the bioassay also highlighted likely occurrences in the field, where several stages of fungal development are encountered simultaneously. CONCLUSION: The present findings were complementary: leaf‐disc tests showed when the fungicides were most effective at inhibiting E. necator infection cycles; the field trial provided results in terms of incidence and severity of disease on bunches without reference to the pathogenic cycle development. A protection strategy combining the different types of fungicide under study is suggested. Copyright © 2010 Society of Chemical Industry 相似文献
83.
Marina Novo Silvia Romo Manuel Rey María Jesús Prado María Victoria González 《Euphytica》2010,175(1):109-121
Fruit set in kiwifruit is strongly dependent on pollination, which is limited by the lack of efficient male pollen donors,
among other factors. We searched for molecular markers that could be polymorphic in relation to flowering time in order to
classify male kiwifruit plants to discard those that are not likely to perform as efficient pollen donors. Random amplified
polymorphic DNA (RAPD) and modified amplified fragment length polymorphism (AFLP) markers were generated using 41 male kiwifruit
plants in two flowering groups, early- and late-flowering males (with respect to the female cultivar ‘Hayward’). One RAPD
and nine modified-AFLP markers polymorphic between male plants exhibiting different flowering time were identified, sequenced
and analysed in databases. Unweighted pair group method with arithmetic average (UPGMA) clustering and multidimensional scaling
showed that these markers could be used to classify the male plants into flowering groups. Analysis of molecular variance
(AMOVA) agreed with this classification, showing that most of the genetic variation is found between flowering groups. Sequence
analysis based on a database search revealed that the polymorphism PolM contains a 7-nucleotide long element involved in the
repression of the phytochrome A gene, that Pol4 is a partial sequence of a phytochrome B gene, and that sequences Pol3, Pol5,
Pol7, and Pol9 show high identity with ESTs from kiwifruit buds treated with hydrogen cyanamide. Clustering analysis supported
the previous classification of males into flowering groups, making it feasible to predict male plants’ flowering times with
respect to the cultivar ‘Hayward’ based upon these molecular markers. 相似文献
84.
The structural changes of Hungarian agriculture in 1989 led to many mountain horticultural farms being abandoned. These structural changes have modified land use patterns which often resulted in decreasing slope stability in mountainous farms. Mahonia aquifolium has been cultivated in Hungary for over half a century for ornamental purposes; however its possible application in shallow slope stabilization has not been discussed. This paper presents the first results on the root morphology, and root tensile strength of M. aquifolium and determines its efficiency for soil protection in horticultural farming practice. Measurements were carried out on M. aquifolium seedlings from cultivated (C) and non-cultivated (NC) soil conditions. The C and NC specimens were measured and compared for root area ratio (RAR) and root tensile strength (TR). These results were then compared with other species for which data was available. Results showed that M. aquifolium plants from C soil conditions had a significantly higher mean RAR with depth than M. aquifolium plants from NC soil conditions. The mean TR results showed no significant difference between M. aquifolium plants from C and NC environments. The study also showed that M. aquifolium's root structure is comparable as soil protection with the other species although a higher degree of soil reinforcement by roots was obtained with C M. aquifolium specimens. M. aquifolium roots could represent effective soil protection. Moreover the plant is well suited to the demands of small-scale horticultural farm practices under mountainous conditions. 相似文献
85.
Frias J Song YS Martínez-Villaluenga C González de Mejia E Vidal-Valverde C 《Journal of agricultural and food chemistry》2008,56(1):99-105
Food allergy has become a public health problem that continues to challenge both the public and the food industry. The objective of this research was the detection and quantification of the major human allergenic soy proteins and to study the reduction in immunoreactivity and improvement of amino acid content after fermentation of soybean flour. Fermentation was carried out in the solid state of cracked seeds inoculated with Aspergillus oryzae, Rhizopus oryzae, and Bacillus subtilis and in the liquid state of milled soybean flours fermented naturally by microorganisms present only in the seeds or by inoculation with Lactobacillus plantarum. ELISA and Western blot were used to quantify IgE antibody response, and HPLC was used to identify and quantify total amino acids. L. plantarum fermented soy flour showed the highest reduction in IgE immunoreactivity (96-99%) depending upon the sensitivity of the plasma used. Among the solid fermented products, the lowest reduction in immunoreactivity was obtained when mold strains, R. oryzae and A. oryzae, were used (66 and 68%, respectively, for human plasma 97.5 kUA/L). Among the solid fermented products, those inoculated with B. subtilis yielded a 81 and 86% reduction in immunoreactivity against both human plasma 97.5 IgE kUA/L and human pooled plasma samples, respectively. When soybean was subjected to liquid fermentation, most of the total amino acids increased significantly ( p < or = 0.05). In solid fermentation with R. oryzae, only Ala and Thr content improved. Fermentation can decrease soy immunoreactivity, and there is potential of developing nutritious hypoallergenic soy products. 相似文献
86.
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88.
Diego A. Luna-Vital Elvira González de Mejía Guadalupe Loarca-Piña 《Plant foods for human nutrition (Dordrecht, Netherlands)》2017,72(4):445-447
The aim was to evaluate the antineoplastic potential of a previously characterized peptide extract from the non-digestible fraction of common bean cv. Azufrado Higuera (AH) and its most abundant pure peptide GLTSK, in an azoxymethane/dextran sodium sulfate (AOM/DSS)-induced colitis-associated colon carcinogenesis Balb/c mice model. The healthy control (C-) had no induction and no treatment, and the induced control (C+) had induction but no treatment. Groups AH and GLTSK were administered 50 mg/kg-bw of AH or GLTSK, respectively. The administration of AH and GLTSK decreased (p < 0.05) the disease activity index (DAI) compared to C+ (5.8, 9.1, 11.8, respectively). Furthermore, AH reduced the number of evident neoplasms compared to group C+ (1.8, 5.9 neoplasms/mice, respectively). The results suggest that peptides from common bean cv. Azufrado Higuera could prevent colitis-associated colon carcinogenesis. 相似文献
89.
Journal of Soils and Sediments - We conducted this investigation in order to develop a simple method for the determination of bioavailable vanadium and its speciation within sediments. The... 相似文献
90.
Temperature-sensitive mutants of bluetongue virus were isolated and classified in 6 genetic recombination groups. The frequency of recombination varied both within and between groups. The 4 mutagens used viz. nitrous acid, N-methyl-N-nitroso-N-nitroguanidine, proflavine and 5-fluoro-uracil were found to differ in their efficacy. The period of incubation required for maximum recombination was 48 h at 28 degrees C. 相似文献