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排序方式: 共有191条查询结果,搜索用时 31 毫秒
1.
Neil A. Bryant Adam S. Rash Alana L. Woodward Elizabeth Medcalf Maud Helwegen Franziska Wohlfender Fatima Cruz Claudia Herrmann Kerstin Borchers Ashish Tiwari Thomas M. Chambers J. Richard Newton Jennifer A. Mumford Debra M. Elton 《Veterinary microbiology》2011,147(1-2):19-27
Like other influenza A viruses, equine influenza virus undergoes antigenic drift. It is therefore essential that surveillance is carried out to ensure that recommended strains for inclusion in vaccines are kept up to date. Here we report antigenic and genetic characterisation carried out on equine influenza virus strains isolated in North America and Europe over a 2-year period from 2008 to 2009. Nasopharyngeal swabs were taken from equines showing acute clinical signs and submitted to diagnostic laboratories for testing and virus isolation in eggs. The sequence of the HA1 portion of the viral haemagglutinin was determined for each strain. Where possible, sequence was determined directly from swab material as well as from virus isolated in eggs. In Europe, 20 viruses were isolated from 15 sporadic outbreaks and 5 viruses were isolated from North America. All of the European and North American viruses were characterised as members of the Florida sublineage, with similarity to A/eq/Lincolnshire/1/07 (clade 1) or A/eq/Richmond/1/07 (clade 2). Antigenic characterisation by haemagglutination inhibition assay indicated that the two clades could be readily distinguished and there were also at least seven amino acid differences between them. The selection of vaccine strains for 2010 by the expert surveillance panel have taken these differences into account and it is now recommended that representatives of both Florida clade 1 and clade 2 are included in vaccines. 相似文献
2.
In weekly intervals water samples of bulk precipitation and different Karst waters from the vadose and phreatic zone of two hydrogeologically and hydrochemically different Karst catchment areas in Upper Franconia (F.R.G.) were taken. Water samples and additional soil, residual loam and sinter samples were analyzed for benzo(a)pyrene, fluoranthene, benzo(ghi)perylene by HPTLC and α-BHC, lindane by GC. Furthermore, partition coefficients of these micropollutants between carbonate water and top soil material, residual loam and dolomite were determined. The calculation of effective equilibrium coefficients between soil water and soil of ambient Rendolls revealed that the thin soil layer of Karst terrains acts as major pollutant sink. Furthermore, co-precipitation of pollutants can occur during the precipitation of dissolved humic material. However, due to rapid percolation of soil and Karst waters 0.3 to 3.3 % of the deposited contaminants can reach the groundwater. 相似文献
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5.
Laetitia Herrmann Lambert Bräu Agnès Robin Henri Robain Wanpen Wiriyakitnateekul Didier Lesueur 《Archives of Agronomy and Soil Science》2016,62(7):1041-1048
Rubber tree is a very important crop in Thailand, representing an essential source of income for farmers. In the past two decades, rubber tree plantations have been greatly expanding in unfavorable areas, where climate conditions are difficult and soil fertility is very poor. To optimize latex yields, mineral fertilizers have been widely used. A better understanding of the roles of the biological compartment in soil fertility is essential to determine alternative management practices to sustain soil fertility and optimize latex yields. Arbuscular mycorrhizal fungi (AMF) are widely recognized as beneficial for plants, mainly through their role in improving plant nutrient uptake. The objective of this study was to assess the AMF populations in rubber tree plantations and the impact of both soil characteristics and plantation age on these communities. Our results showed that all rubber trees were highly colonized, regardless of the soil structure and nutrient contents. AMF colonization was not affected by the age of the trees, suggesting that maintaining the symbiosis is likely to be beneficial at all stages. A better understanding and management of the microbial communities would contribute to maintaining or restoring soil fertility, leading to a better tree growth and optimized latex yield. 相似文献
6.
The number of genotypes investigated per population is important for the reliability of diversity studies. The objective of
this study was to determine the sample size for the identification of differences among populations of an outcrossing autotetraploid
species, alfalfa (Medicago sativa), using codominantly coded SSR markers. One hundred and twenty genotypes from each of two closely related populations were
analysed with two markers. Twenty random subsamples for each of three sample sizes (10, 20 and 40 genotypes) were built. Compared
to the populations with 120 genotypes, alleles that were no longer present in subsamples with 40 genotypes were mainly rare,
whereas abundant alleles were also excluded in subsamples with 10 genotypes. F
ST values for pairs of subsamples between the two populations were always significantly different based on 40 genotypes, whereas
for 10 genotypes more than half of the pairs were not significantly different. We concluded that 40 genotypes are a reasonable
sample size for diversity studies with closely related populations of tetraploid alfalfa investigated with SSR markers. Twenty
genotypes may be an economical alternative for large scale studies, but 10 genotypes were a too low number for reliable results. 相似文献
7.
Stefan Patzold Franz Michael Mertens Ludger Bornemann Britta Koleczek Jonas Franke Hannes Feilhauer Gerhard Welp 《Precision Agriculture》2008,9(6):367-390
Crop protection seldom takes into account soil heterogeneity at the field scale. Yet, variable site characteristics affect
the incidence of pests as well as the efficacy and fate of pesticides in soil. This article reviews crucial starting points
for incorporating soil information into precision crop protection (PCP). At present, the lack of adequate field maps is a
major drawback. Conventional soil analyses are too expensive to capture soil heterogeneity at the field scale with the required
spatial resolution. Therefore, we discuss alternative procedures exemplified by our own results concerning (i) minimally and
non-invasive sensor techniques for the estimation of soil properties, (ii) the evidence of soil heterogeneity with respect
to PCP, and (iii) current possibilities for incorporation of high resolution soil information into crop protection decisions.
Soil organic carbon (SOC) and soil texture are extremely interesting for PCP. Their determination with minimally invasive
techniques requires the sampling of soils, because the sensors must be used in the laboratory. However, this technique delivers
precise information at low cost. We accurately determined SOC in the near-infrared. In the mid-infrared, texture and lime
content were also exactly quantified. Non-invasive sensors require less effort. The airborne HyMap sensor was suitable for
the detection of variability in SOC at high resolution, thus promising further progress regarding SOC data acquisition from
bare soil. The apparent electrical conductivity as measured by an EM38 sensor was shown to be a suitable proxy for soil texture
and layering. A survey of arable fields near Bonn (Germany) revealed widespread within-field heterogeneity of texture-related
ECa, SOC and other characteristics. Maps of herbicide sorption and application rate were derived from sensor data, showing
that optimal herbicide dosage is strongly governed by soil variability. A phytoassay with isoproturon confirmed the reliability
of spatially varied herbicide application rates. Mapping areas with an enhanced leaching risk within fields allows them to
be kept free of pesticides with related regulatory restrictions. We conclude that the use of information on soil heterogeneity
within the concept of PCP is beneficial, both economically and ecologically. 相似文献
8.
Henrich Herrmann 《Forstwissenschaftliches Centralblatt》1915,37(2):51-60
Ohne Zusammenfassung 相似文献
9.
K Krawielitzki U Hennig T Zebrowska J Kowalczyk U Herrmann 《Archives of Animal Nutrition》1990,40(1-2):17-23
An experiment was carried out using pigs weighing approximately 30 kg. The animals were fitted with two re-entrant cannulas in duodenum and ileum. During a 5 day period the passage of digesta through duodenum and ileum as well as the excretion by urine and faeces was estimated, taking an aliquot of 5% for N analysis. Transit of digesta amounted to 12.4 ... 13.2. kg/d in the duodenum and 2.7 ... 3.6 kg/d in the ileum. The appertaining N passage rates were 36.8 ... 42.4 resp. 8.7 ... 11.2 g N/d, corresponding to 108 ... 120% and 27 ... 32% of the N intake. The transit rate of duodenal digesta was highest immediately after feeding (1.4 ... 1.5 kg/h), decreased thereafter strongly, reaching a second lower maximum of 0.85 ... 1.0 kg/h 2 ... 3 h after feeding and then going down to 0.3 ... 0.4 kg/h just before the next feeding. The daily mean value was about 500 g/h. Endogenous N content of duodenal digesta varied between 10% after feeding and 50% 6 ... 12 h after feeding, with an average of 18.1%. In contrast the endogenous N content of ileal digesta was relatively constant amounting about 42% during the whole day. These findings correspond with those found by other authors using other rations and other live weights of the pigs. They refer to a clear diurnal rhythm of digesta transit and to the enormous dynamics of absorption and secretion processes in the intestinal tract of pigs during digestion.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
10.
Production of Haploid Sugar Beet (Beta vulgaris L.) by Culturing Unpollinated Ovules 总被引:4,自引:0,他引:4
The culture of unpollinated ovules is shown to be a suitable system for the production of haploid sugar beet (Beta vulgaris L.). The yield of haploids depended upon the genotype and varied between 0 and 13 % with a mean of 1.0 %. Haploid plants could be produced from approximately 50 % of all genotypes examined. The majority of the haploids isolated (about 90%) maintained the haploid genome level during the in vitro culture and propagation; 10% of the haploid clones showed a spontaneous doubling to the diploid genome level. 相似文献