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991.
Avia E. Rubin Ayelet-Chen Werdiger Mathias Blum Ulrich Gisi Helge Sierotzki Dietrich Hermann Yigal Cohen 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(2):339-351
Wild type (WT) field isolates of Bremia lactucae failed to germinate in vitro or infect lettuce leaves in the presence of CAA (carboxylic acid amide) fungicides. Minimal
inhibitory concentrations (MIC) for mandipropamid, dimethomorph, benthiavalicarb and iprovalicarb were 0.005, 0.5, 0.5 and
5 μg ml−1, respectively. Mutagenesis experiments showed that spores exposed to EMS (ethyl methane sulphonate) or UV irradiation (254 nm)
could infect lettuce leaves in the presence of up to 100 μg ml−1 CAA. The proportion of infected leaves relative to the number of spores inoculated (infection frequency) was inversely related
to the concentration of CAA used, ranging between 0 and 160 per 1 × 106 spores. Resistant mutants (RM) lost their resistance within 1–14 reproduction cycles on CAA-treated plants. Crosses were
made between RMxWT isolates and RMxRM isolates with an attempt to obtain stable homozygous resistant off-springs. Such crosses
yielded few resistant but unstable progeny isolates. Mutagenic treatments given to hybrid isolates also failed to produce
stable resistance. Previous gene sequencing data showed that stable resistance to CAAs is based on a single SNP in the cellulose synthase 3 (CesA3) gene of Plasmopara viticola. Therefore, we sequenced a 582 bp DNA fragment of Ces3A of WT, RM and hybrid isolates of B.lactucae. No mutation in this gene fragment was found. We conclude that mutagenic agents like EMS or UV may induce resistance to CAA
in Bremia lactucae but this resistance is not stable and not linked to mutations in CesA3 gene. 相似文献
992.
Yan-Xiang Qi Xin Zhang Jin-Ji Pu Xiao-Mei Liu Ying Lu He Zhang Hui-Qiang Zhang Yan-Chao Lv Yi-Xian Xie 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(1):83-95
Twenty-two isolates of Corynespora cassiicola obtained from cucumber, papaya, eggplant, tomato, bean, Vigna, sesame and Hevea rubber (Hevea brasiliensis) were analysed by morphological features, the differences of the ribosomal DNA internal transcribed spacer (rDNA-ITS) region
sequence and the inter simple sequence repeat (ISSR) technique. Variability of morphological features was observed among the
isolates. Pathogenicity tests showed that isolates from different hosts attacked Hevea rubber. Sequences of two outgroup taxa, C. proliferata and C. citricola, were downloaded from GenBank. The phylogenetic trees were constructed by using the rDNA-ITS region sequences from 24 Corynespora
spp. isolates. In this analysis, the 24 sequences grouped into two clusters (A and B). Cluster A consists of sequences from
all isolates of C. cassiicola; whereas cluster B consists of the two outgroup taxa, C. proliferata and C. citricola. However, the ITS region is conservative, and is not fit for studying differences among isolates. A total of 114 DNA fragments
was amplified with 16 ISSR primers, among which 102 were polymorphic (89.5%). A dendrogram was created by the unweighted pair-group
method with arithmetic averaging (UPGMA) analysis, and 22 isolates grouped into three clusters (C, D and E). Cluster C is
composed of all of the Hevea rubber isolates, whereas cluster D is composed of nine isolates: four from papaya, five from cucumber, eggplant, bean, vigna
and sesame. Cluster E is composed of two isolates from cucumber and tomato. These analyses showed that the genetic diversity
was very rich among the tested isolates. There are no correlations between the morphological characteristics or rDNA-ITS region
sequences of the 22 isolates and their host or geographical origin, but there is a link between ISSR clusters and their host
origins. ISSR markers appear to be useful for intra-species population study in C. cassiicola. 相似文献
993.
Nadia Korolev Mukhiddin Mamiev Tirza Zahavi Yigal Elad 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(4):591-608
Plots in two vineyards in the Golan Heights, Israel were treated with six botryticides during three growing seasons with 3
applications per season. Applications of fenhexamid, pyrimethanil and cyprodinil + fludioxonil were effective, resulting in
52–65% and 53–63% mean reduction in grey mould incidence and severity, respectively. Carbendazim, fluazinam and iprodione
were ineffective or slightly effective. Five hundred and sixteen B. cinerea isolates were collected from infected berries or trapped from the air in the vineyards, and profiles of sensitivity to benomyl,
fenhexamid, fluazinam, fludioxonil, iprodione and pyrimethanil were established for each of the isolates based on a mycelial
growth test. Seventy-four percent of the isolates were sensitive to the six tested fungicides, and the other 26% of the isolates
were classified into 10 phenotypes characterized by resistance to one or more fungicides. Resistant isolates showed fitness
parameters similar or reduced in comparison to sensitive isolates. Resistance to benzimidazoles and to dicarboximides was
the most frequent (up to 25%) and apparently pre-existed in the populations tested. Increased frequency of benzimidazole resistance,
but not dicarboximide resistance, was observed following the 3 years of applications of the fungicides. High level resistance
to pyrimethanil was present at a frequency of about 2% in both vineyards in the first 2 years of the sampling survey and reached
10% in the third year at Site 2. A few isolates were resistant to fenhexamid or fludioxonil (0.8 or 0.2%, respectively). No
strong resistance to fluazinam was detected, although numerous, less sensitive isolates, presumably possessing multi-drug
resistance traits, were recovered at higher frequency from the plots treated with fluazinam than from the untreated plots. 相似文献
994.
Piérri Spolti Luana Schneider Rosa M. V. Sanhueza Jean C. Batzer Mark L. Gleason Emerson Medeiros Del Ponte 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(1):21-29
Sooty blotch and flyspeck is caused by numerous species of fungi that colonize the surface of apple fruit and thereby lower
its market value. Although this disease poses a substantial threat to apple growers’ profitability in some regions, reliable
and cost-effective methods for epidemiological and disease control studies have not been validated, nor are they widely available.
We modified a standard area diagram to aid sooty blotch and flyspeck severity assessments and quantified its impact on accuracy
and precision of visual estimates. Samples of ‘Fuji’ and ‘Mutsu’ fruit were photographed both from the top and laterally.
Severity was assessed from a sub-sample of 160 images using image analysis software. Validation of the diagram was performed
by eight raters who independently assessed severity in two series of selected images representing the lateral view and the
top view, initially unaided and subsequently with the aid of the scale. Severity estimates ranged from 0.4% to 98% (most fruit
had <10% severity). Accuracy and precision of the estimates were significantly improved when using the diagrammatic scale;
concordance correlation coefficient values increased from 0.81 to 0.95. A strong tendency to underestimate severity for the
mid-range to high levels was minimized when using the aid, which also improved reproducibility of the estimates among raters.
In addition to strengthening evidence that a standard area diagram can be used reliably in sooty blotch and flyspeck studies,
we expanded its application to disease assessment in the peduncle region, which enhances the usefulness of the method for
evaluating efficacy of management practices. 相似文献
995.
Rasa Jomantiene Yan Zhao Ing-Ming Lee Robert Edward Davis 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(1):97-107
Phytoplasmas infecting sour cherry and lilac in Lithuania were found to represent two lineages related to clover phyllody
phytoplasma (CPh), a subgroup 16SrI-(R/S)C (formerly 16SrI-C) strain exhibiting rRNA interoperon sequence heterogeneity. 16S
rDNAs amplified from the cherry bunchy leaf (ChBL) and lilac little leaf (LcLL) phytoplasmas were identical or nearly identical
to those of operon rrnA and operon rrnB, respectively, of CPh. There was no evidence of 16S rRNA interoperon sequence heterogeneity in either LcLL or ChBL phytoplasma.
Based on collective RFLP patterns of 16S rDNA, ChBL was classified in subgroup 16SrI-R, and LcLL was classified in new subgroup
16SrI-S. The ribosomal protein (rp) gene sequences from LcLL phytoplasma were identical to those of CPh, and strain LcLL was
classified in rp subgroup rpI-C. By contrast, rp gene sequences from ChBL phytoplasma differed from those of subgroup rpI-C;
based on RFLP patterns of rp gene sequences, ChBL was classified in new rp subgroup rpI-O. Single nucleotide polymorphisms
(SNPs), designated here by a new SNP convention, marked members of rp subgroup rpI-C, and distinguished LcLL and CPh from
ChBL and other non-rpI-C phytoplasmas in group 16SrI. The results raise questions concerning phytoplasma biodiversity assessment
based on rRNA genes alone and encourage the supplemental use of a single copy gene in phytoplasma identification and classification,
while drawing attention to a possible role of horizontal gene transfer in the evolutionary history of these lineages. 相似文献
996.
Warrick R. Nelson Tonja W. Fisher Joseph E. Munyaneza 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(1):5-12
Three haplotypes of the recently discovered bacterium species “Candidatus Liberibacter solanacearum” are described and related to geographic ranges. The first two are associated with Zebra Chip/Psyllid
Yellows of potatoes and other solanaceous plants, vectored by the tomato/potato psyllid Bactericera cockerelli in North and Central America and New Zealand. The third is associated with diseased carrots in Finland and vectored by the
carrot psyllid Trioza apicalis. The haplotypes are described by SNPs on the 16s rRNA, 16s/23s ISR and 50s rplJ and rplL ribosomal protein genes. These SNPs
are inherited as a package across the three genes. Haplotype “a” has been found primarily from Honduras and Guatemala through
western Mexico to Arizona and California, and in New Zealand. Haplotype “b” is currently known from eastern Mexico and northwards
through Texas to south central Washington. These haplotypes show some range overlap in Texas, Kansas and Nebraska. The haplotypes
are not yet known to elicit biological differences in the plant or insect hosts. These apparently stable haplotypes suggest
separate bacterial populations of long standing. 相似文献
997.
Odile Carisse Catherine Meloche William W. Turechek 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(3):349-365
The spatial pattern of apple scab was characterized using 10 years of disease incidence and lesion density data collected
in managed orchards located in Quebec, Canada. Distributional analyses indicated that scab incidence was better characterized
by the beta-binomial than the binomial distribution in 53 and 65% of the data sets at the leaf and shoot scales, respectively.
Median values of the beta-binomial parameter θ, a measure of small-scale aggregation, were near 0 (0.003 and 0.028) at both
sampling scales, indicating that disease incidence was close to being randomly distributed (low degree of aggregation). For
lesion density, the negative binomial distribution fitted the data better than the Poisson distribution in 86% of the data
sets at the leaf scale. The median value of the index of dispersion k was 0.068, indicating that aggregation was present. For all apple scab measurements, the power law models provided a good
fit to the data. The estimated slope and intercept parameters were significantly greater than 1 and 0, respectively, suggesting
that spatial heterogeneity changed systematically with disease incidence. Results of a covariance analysis showed that spatial
heterogeneity of scab incidence at both scales and lesion density was not dependent upon shoot type but that spatial heterogeneity
of scab incidence and lesion density at the leaf scale was influenced by the sampling period. A hierarchical analysis showed
that scab incidence at the tree scale increased as a saturation-type curve with respect to incidence at the leaf or shoot
scales. A similar relationship was observed for incidences at the shoot and leaf scales. An effective sample size model based
on the binary power law parameters (Madden and Hughes, Phytopathology 89:770–781, 1999) gave the best fit to the leaf and shoot data, respectively. The incidence-lesion density relationship at both scales was
well described by a complementary log-log (CLL) and log transformation model ( Radj2 = 0.97 and Radj2 = 0.94 ) \left( {R_{{adj}}^2 = 0.97\,and\,R_{{adj}}^2 = 0.94} \right) , however, the models tended to underestimate lesion density. The information of the spatial relations of apple scab within
and between hierarchical scales acquired from this study can be used in developing and evaluating practical disease management
strategies and to improve apple scab assessments for fungicide or cultivar susceptibility trials. 相似文献
998.
Otmar Spring Thines Marco Stefanie Wolf Reinhard Zipper 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(3):519-527
Sequencing of partial cox2 (part of the mitochondrial cytochrome-c-oxydase (COX) gene) was performed with samples from the oomycete genus Pustula, the white blister rusts of Asteraceae and related families. Sequence comparison uncovered several single nucleotide polymorphisms
(SNPs) between P. spinulosa and host specific strains of Pustula isolated from Senecio vulgaris, Tragopogon pratensis and cultivated sunflower, Helianthus annuus. Based on these differences, specific primers were designed for PCR-based detection of white blister rust strains pathogenic
to sunflower. The specificity of the primers was confirmed by cross testing with DNA from various oomycetes occurring in the
same locality. The limit of detection for DNA of P. helianthicola was 10 pg. This allowed detection with DNA from single sporangia and single oospores. The PCR-based experiments allowed detection
of the presence of sunflower white blister rust in soil samples from fields on which infected plants had been cultivated several
months before. Moreover, the molecular tools were successfully applied to trace the pathogen in asymptomatic tissue of infected
plants, demonstrating the systemic nature of Pustula on sunflower. 相似文献
999.
Monique L. Sakalidis Jane D. Ray Vincent Lanoiselet Giles E. StJ. Hardy Treena I. Burgess 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(3):379-391
Members of the Botryosphaeriaceae, in particular Lasiodiplodia theobromae, Neofusicoccum parvum, N. mangiferum and Botryosphaeria dothidea, commonly cause stem cankers, dieback and stem end rot of mangoes worldwide. In the current study, eight taxa of Botryosphaeriaceae
were identified as canker-associated fungi, pathogens, potential pathogens or endophytes of mangoes in the Kimberley, Australia.
These include Neoscytalidium novaehollandiae, Ne. dimidiatum, Pseudofusicoccum adansoniae, P. ardesiacum, P. kimberleyense, Lasiodiplodia sp. 1, L. iraniensis and L. pseudotheobromae. The pathogenicity of a selection of these species toward fruit and branches was tested. All were pathogenic to mango in comparison
to the control, with Lasiodiplodia spp. being the most pathogenic. It appears that either geographic isolation or the unique growing conditions in the Kimberley
may have provided an effective barrier to the acquisition or establishment of known botryosphaeriaceous pathogens. Wounds
caused by mechanical pruning may provide an entry point for infection, whilst severe pruning may increase plant stress. 相似文献
1000.
Maria Teresa Melillo Paola Leonetti Antonella Leone Pasqua Veronico Teresa Bleve-Zacheo 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(4):489-502
Nitric oxide (NO) has been shown to be an essential regulatory molecule in plant response to pathogen infection in synergy
with reactive oxygen species (ROS). At the present, nothing is known about the role of NO in disease resistance to nematode
infection. We used a resistant tomato cultivar with different sensitivity to avirulent and virulent populations of the root-knot
nematode Meloidogyne incognita to investigate the key components involved in oxidative and nitrosative metabolism. We analyzed the superoxide radical production,
hydrogen peroxide content, and nitric oxide synthase (NOS)-like and nitrate reductase activities, as potential sources of
NO. A rapid NO accumulation and ROS production were found at 12 h after infection in compatible and incompatible tomato-nematode
interactions, whereas the amount of NO and ROS gave different results 24 and 48 h after infection amongst compatible and incompatible
interactions. NOS-like arginine-dependent enzyme rather than nitrate reductase was the main source of NO production, and NOS-like
activity increased substantially in the incompatible interaction. We can envisage a functional overlap of both NO and ROS
in tomato defence response to nematode invasion, NO and H2O2 cooperating in triggering hypersensitive cell death. Therefore, NO and ROS are key molecules which may help to orchestrate
events following nematode challenge, and which may influence the host cellular metabolism. 相似文献