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41.
Genetic diversity among 51 isolates of Rhizoctonia solani AG-3, representing potato and tobacco populations, was inferred from the sequences of the internal transcribed spacer (ITS) and 5.8S ribosomal RNA (rRNA) gene. The 5.8S rDNA sequence was completely conserved not only in AG-3, but across all the AG isolates examined, whereas the rDNA-ITS sequence was found to be variable among the isolates. The nucleotide sequence similarity in the ITS 1 region was high (96-100%) for isolates within each of the two populations, but was 91-92% for isolates from different populations. The AG-3 isolates had 56 to 91% sequence similarities in the ITS 1 region with R. solani isolates of the other AGs. Phylogenetic analysis based on the ITS-5.8S rDNA sequence data indicated that the different populations in AG-3 are distantly related to each other. Genetic divergence between the two populations was also supported by the results of DNA-DNA hybridization studies. This study suggests that AG-3 consists of two genetically isolated groups corresponding to separate subgroups: AG-3 PT (potato type) and AG-3 TB (tobacco type). Specific primer sets for the detection of the two AG-3 subgroups were developed from the aligned rDNA-ITS sequences. Received 22 April 1999/ Accepted in revised form 2 July 1999  相似文献   
42.
It is believed that some organic compounds form complexes with iron and aluminum and prevent the fixation of phosphate applied to soils.  相似文献   
43.
ABSTRACT:   Gnomefish Scombrops boops and Scombrops gilberti are commercially important fishes in Japan, but these species are often confused in the markets because of their morphological similarity. To identify these two species, we performed nucleotide sequencing and restriction fragment length polymorphism (RFLP) analysis on 16S ribosomal RNA (rRNA) gene and the control region in mitochondrial DNA. Five and 12 nucleotide substitutions were observed between species in the 777-bp 16S rRNA gene and 471-bp control region, respectively. Diagnostic restriction sites for discriminating between S. boops and S. gilberti were found in the 16S rRNA gene, but not in the control region. Polymerase chain reaction (PCR)–RFLP analysis using two enzymes, Eco NI and Mva I, clearly discriminated between S. boops and S. gilberti identified by meristic characters. The PCR–RFLP analysis identified most of the 168 Scombrops young caught in the coastal waters of the Izu and Miura peninsulas as S. boops , suggesting that S. gilberti juveniles are rare in this area.  相似文献   
44.
Ruminant animals are able to convert plant materials (grain and the human‐indigestible portion of carbohydrates) to milk and meat. In this conversion, most of the plant materials are digested by rumen fermentation and are changed to short‐chain fatty acids, microbial cells, and methane, which is released into the atmosphere. The relationships among feed, rumen fermentation, and milk production are poorly understood. Here we report a novel indicator of characteristics of rumen fermentation, theoretical turnover rate (TTOR) of the rumen liquid fraction. The TTOR was calculated from the presumed rumen volume (PRV) which is estimated by dividing the methane yield by the methane concentration of rumen fluid. The formula for the TTOR is: TTOR = PRV/body weight0.75. Our present analyses confirm that the TTOR as an indicator is capable of connecting feed, rumen fermentation, and milk production, because dry matter intake/TTOR showed a strong correlation with milk yield/TTOR. In addition, the TTOR may be related to ruminal pH, as we observed that the ruminal pH decreased as the TTOR increased. We propose that the TTOR is a factor characterizing rumen fermentation and a good indicator of the productivity of ruminants and dysbiosis of the rumen microbiome.  相似文献   
45.
We conducted two feeding experiments to evaluate the effects of supplementation with either cellooligosaccharide or kraft pulp on growth performance in grazing beef calves (Japanese Black) from 4 weeks pre‐weaning to 12 to 16 weeks post‐weaning. In Experiment 1 (20‐week duration), nine calves (2.9‐month‐old females) were assigned to either a control group (CON) or an experimental group (CEL) fed cellooligosaccharide at a rate of 10 g/day mixed with concentrate. Average daily weight gain tended to be greater in CEL than in CON, especially after 1 month of weaning. In Experiment 2 (16‐week duration), 10 calves (2.0‐month‐old females) were assigned to either a control group or an experimental group (KRA) fed kraft pulp at a rate of 10% replacement of total digestible nutrients with concentrate. The proportion of fibrolytic bacteria increased and that of methanogenic Archaea decreased in the rumen microbial community composition of KRA calves in Experiment 2, whereas the decrease in Fibrobacter and Archaea was observed in CEL calves at first 4 weeks in Experiment 1. We conclude that beta‐glucan prebiotic supplementation to grazing calves at pre‐weaning would affect rumen microbial composition and modified rumen fermentation characteristics, leading to a better rumen environment via different means.  相似文献   
46.
To enhance the photostability of wood against ultraviolet (UV) light, a UV absorbent, 2,2,4-trihydroxy-4-[2-hydroxy-3-(3-trimethoxysilylpropoxy)propoxy]benzophenone (BP), was applied to the reaction system for preparing SiO2 wood–inorganic composites by sol–gel reaction. The BP–SiO2 wood–inorganic composites obtained were examined for photostability by scanning electron microscope observations, color changes, and diffuse reflectance infrared fourier transform analyses. The results clearly indicated that compared with SiO2 composites, BP–SiO2 composites improved the photostability of wood. In addition, BP was stable against UV light without degradation so that the BP–SiO2 composite should provide sustainable and high photostability of treated wood.Part of this report was presented at the 51st Annual Meeting of the Japan Wood Research Society at Tokyo, April, 2001  相似文献   
47.
Heavy thinning may provide a feasible means to convert single-species coniferous plantations to broadleaved or mixed forests. To assess this possibility, we monitored tree seedling dynamics of other tree species, the understory microenvironment, and seed availability following heavy thinning (50 % by volume) in two hinoki (Chamaecyparis obtusa) plantations in Shikoku, southwestern Japan. Conventional (35 % by volume) and row thinning (50 % by volume) treatments were also applied at one of the sites. Diffuse transmittance in the understory dramatically increased after all thinning treatments then rapidly decreased, except after row thinning. Heavy thinning accelerated recruitment of small seedlings (with stems <30 cm high) at one of the sites. However, the densities of these seedlings declined sharply, and increases in the densities of larger seedlings recorded in subsequent surveys were very small. Furthermore, at the other site, recruitment of small seedlings under heavy thinning was equivalent to that under conventional thinning and lower than that under row thinning. Abundant species in the recruited seedlings were pioneer or subcanopy species found in the soil seed bank. Low seed rain density at both sites appeared to be responsible for the poor recruitment of canopy tree species. Our results suggest that heavy thinning had limited effects on the seedling recruitment of other tree species in these hinoki plantations due to insufficient seed rain and rapid canopy closure.  相似文献   
48.
49.
Pyrolysis behavior of levoglucosan (1,6-anhydro--d-glucopyranose), the major anhydromonosaccharide formed during cellulose pyrolysis, was studied at 250°–400°C under nitrogen. The pyrolysis products were found to change stepwise: levoglucosan MeOH-soluble fraction (lower-molecular-weight products and oligosaccharides) water-soluble fraction (polysaccharides) insoluble fraction (carbonized products). From the present experimental results, a pathway of cellulose pyrolysis via anhydromonosaccharide is proposed including polymerization to polysaccharides (a reversible reaction) as a key reaction to carbonized product formation.Part of this study was presented at the XIXth International Carbohydrate Symposium, San Diego, August 1998; and the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000  相似文献   
50.
Effects of side chain hydroxyl groups on pyrolytic β-ether cleavage of phenolic model dimers were studied with various deoxygenated dimers under pyrolysis conditions of N2/400°C/1 min. Although phenolic dimer with hydroxyl groups at the C α and C γ positions was much more reactive than the corresponding nonphenolic type, deoxygenation at the C γ -position substantially reduced the reactivity up to the level of the nonphenolic type. These results are discussed with the cleavage mechanism via quinone methide intermediate formation, which is activated through intramolecular hydrogen bonds between C α and C γ hydroxyl groups.  相似文献   
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