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31.
This article describes procedures for studying parameters connected with the genotype-by-environment interactions appearing in a mixed model derived from the randomization principle. It considers estimation of these parameters and of their meaningful functions. A test for the overall no-interaction hypothesis is described, and relevant tests for some implied hypotheses concerning individual parametric functions are considered. Useful data transformations are proposed that allow the graphic presentation of interesting features of the genotype-by-environment interactions. The theoretical considerations are illustrated by an analysis of the results of a series of trials with pea varieties.  相似文献   
32.

? Key message

Long-term strict protection of woodland communities may lead to their compositional simplification and homogenisation.

? Context

In the past, it has often been postulated that structures and processes typical for natural forests should be mimicked by silvicultural activities in the case of managed tree stands.

? Aims

To determine which features and traits of natural woodland communities (alongside typical old-growth attributes) should be imitated in managed forests, as well as which should not (and for what reasons).

? Methods

Tree data from five permanent study plots (of a total area of 15.44 ha) established in 1936 in the core area of the Bia?owie?a National Park (NE Poland) are used to calculate several quantitative indices describing the temporal dynamics (in terms of stand structure and composition) of eight major woodland community types.

? Results

Most structural attributes revealed rather high stability over time. In contrast to these, during the observation period, noticeable changes in the composition of particular Bia?owie?a woodland communities have been taking place, related to declining occurrence and reduced roles characteristic for a large number of tree species.

? Conclusion

In many ways, natural forests can serve as an important model for managed forest stands. However, in certain circumstances, silvicultural treatments counteracting natural developmental trends may appear to be indispensable, especially when more diverse and stable tree species composition (at a given spatial and temporal scale) is indicated or desirable.
  相似文献   
33.
A total of 80 Russian tortoises brought in Poland were examined for presence of Salmonella. Salmonella was detected in 15 out of all the animals tested (18.75%). Of the total of 56 strains, 30 (53.57%) belonged to Salmonella enterica subsp. enterica (I) and 26 to Salmonella enterica subsp. salamae (II). The predominant serotype within subspecies I was S. Newport, which is one of the most serotypes causing salmonellosis in humans and warm-blooded animals. In vitro determination of the susceptibility of Salmonella to the 10 medicinal preparations showed that all tested strains were sensitive to norfloxacin, sulfamethoxazole with trimethoprim, florfenicol, gentamicin, tetracycline and ampicillin, resistance was noted only to amoxicillin with clavulanic acid (12 strains), and intermediate sensitivity to colistin (7 strains), enrofloxacin (2 strains) and cephalexin (5 strains). These studies confirmed that Russian tortoises are a significant reservoir for Salmonella and may represent a potential source of infection for humans.  相似文献   
34.
A previous investigation of thechemical characteristics of precipitation in theWielkopolski National Park has shown its high acidity,which sometimes drops below pH 3.0. This paper dealswith the leaching of potassium and sodium ions by acidrain from typical soils of the study area. Laboratoryexperiments were conducted on undisturbed soil cores(15 cm in diameter, 50 cm high) with acid solutions of pH 3.0, pH 2.0 and with water of pH 5.6 (control). The sprinkling lasted 30 days simulating a rainfall of 400 mm. The eluates were analysed daily. Soil propertiesand forms of potassium and sodium were determinedbefore and after treatment. The investigations showthat quite significant amounts of K+ andNa+ can be leached from the soil: in the very acidtreatment (pH 2.0) about 4 mg K+ and 3 mgNa+ per kg of soil. The leaching of these elementswas smaller in the pH 3.0 and 5.6 treatments.Differences in the dynamics of the process are shownin the leaching curves. In the case of potassium theirshapes are smooth when pH is 5.6 and 3.0, while at pH2.0 the curves rise sharply. The leaching curves inthe case of sodium do not show sharp peaks, whichmeans that the leaching is slow and equalised.  相似文献   
35.
Soil testing is used to help make fertilizer recommendations for greater yields and profits. But the increase of soil‐sampling density raises costs of sample collection and analyses. The aim of this study was to compare grid‐cell sampling densities (1, 2, and 4 ha) in terms of the estimation accuracy of macronutrients (P, K, Mg) availability and pH and to investigate how sampling density affects the amount of fertilizers and lime recommended and correctly applied to winter wheat (Triticum aestivum L.). The distribution of liming requirements and available nutrients were quite similar for the 1‐ and 2‐ha grids but notably different for the 4‐ha grid. However, the whole‐field average values of pH and P, K, and Mg concentrations in soil obtained for different sampling densities were very similar, thus placing, respectively, the soil of the studied area in the same class of liming needs and nutrient availability. The range and estimation errors of these parameters decreased with sampling‐grid size increase. The amount of lime and fertilizers to be applied on the field and the portion of a field correctly limed or fertilized depended on the soil chemical property considered. If one treats the 1‐ha grid as the reference and the most correct soil‐sampling approach, 2‐ha grid offered the greatest part of the field to be adequately fertilized with lime, P, and K. However, fertilization with Mg was much more appropriate if the recommendation was based on 4‐ha, than on a 2‐ha soil‐sampling grid. To gain an insight into soil variation and soil process occurring at small scale, laboratory and geostatistical analyses on individual soil samples may be necessary in some cases. Possibly, such costly research can deliver relevant information which could be then applied into farmer's practice.  相似文献   
36.
The work investigates the possibility of the protective action of kaempferol on phosphatidylcholine liposome membranes exposed to the pro-oxidative action of diphenyltin dichloride (DPhT) and triphenyltin chloride (TPhT) induced by UV radiation (lambda = 253.7 nm). The concentrations of kaempferol and its equimolar mixtures with DPhT and TPhT were determined so that they induce 50% inhibition in oxidation of liposomes irradiated with UV. They are 11.6, 10.0, and 4.5 microM/L, which constitute the following sequence of antioxidative activity: kaempferol/triphenyltin > kaempferol/diphenyltin > kaempferol. This relationship is confirmed by the results on the antiradical ability of kaempferol and its mixtures with DPhT and TPhT toward the free radical 2,2-diphenyl-1-picrylhydrazyl. Similar sequences obtained in both studies suggest a possible mechanism of the antiradical action of the mixtures as free radical scavengers. Kaempferol's ability, then documented, to form complexes with phenyltins indicates (a) a possible way to liquidate the peroxidation caused by the free radical forms of phenyltins and (b) the stabilizing role of chelating in the antioxidative action of the kaempferol/phenyltins. The differentiation in the action of the compounds studied may, among others, result from different localizations in the liposome membrane, which is indicated by the results of the fluorometric studies.  相似文献   
37.
Disappearance of pyrimethanil residues on tomato plants   总被引:6,自引:0,他引:6  
The objective of this work was to estimate the disappearance of pyrimethanil, the active ingredient of Mythos 300 SC, at present, commonly used for the protection of greenhouse vegetables against diseases of fungal origin. Disappearance trends of the chemical deposits were studied on tomato plants grown in commercial greenhouses sprayed with a homogeneous 0.15% aqueous solution of the plant protection product. It was found that, on average, pyrimethanil residues on ripening fruits dropped by half and reached detection limit level in 5.7 and 13.7 days after Mythos 300 SC application, respectively. Pyrimethanil residues on tomato leaves dropped by half within 4.0 days and reached detection limit level in the first 10.5 days. Therefore, in conditions of high infection pressure, there is a need to repeat the fungicide application as early as after 3 or 4 days after previous application of Mythos 300 SC.  相似文献   
38.
New Forests - Cultivation of seedlings in trays requires the use of specifically developed substrates. This study presents the results of the analyses of selected physical and mechanical parameters...  相似文献   
39.
Results presented in this paper come from two long-term fertilization experiments carried out in Skierniewice (since 1923) and _ yczyn (since 1960). The top layer of soil in Skierniewice contains a little more clay and silt (17%) than at _ yczyn (14%), but the climatic conditions are alike - the mean for many years shows the precipitation of 520mm and temperature 7,9°C. Soil samples for the determination of microelements were collected in the years 1999 and 2000 from the control plots (Ca) and from combinations corresponding to 3 fertilization systems: mineral (CaNPK), organic (Ca + FYM) and mixed organic-mineral (CaNPK + FYM). The contents of B, Cu, Zn, Mn were determined in 4 extract solutions: 0,01mol CaCl2, EDTA, 1mol HCl and HF (total contents). The paper presents average results for the last two years. The following amounts of microelements (%) in relation to the total contents in particular extract solutions were obtained: CaCl 2 m Cu 0,4< Zn 2,2< Mn 3,5 < B 5,0; EDTA - B 2,4 < Mn 5,7 < Zn 9,0 < Cu 13,9; HCl - B 7,8 < Cu 37,3 < Zn 37,6< Mn 72,5. The soil contents of readily soluble forms of Mn were significantly higher in non-limed than in limed soil, while the amounts of B, Cu and Zn were higher in limed soils as some amounts of Cu and Zn were present in lime fertilizers. In the system of mineral fertilization, some amounts of boron and zinc were introduced to the soil together with fertilizers, however, they were insufficient in view of nutritional requirements. On the other hand, in the organic-mineral system the amounts of introduced boron were adequate, copper and zinc twice higher and manganese four times higher. The use of mineral fertilization alone for 26 years, leads to soil depletion of zinc and copper and the use of manure alone enriches soil in those components.  相似文献   
40.
The negative impact on the environment caused by intensive agriculture has been extensively discussed for years. In particular, excessive nitrogen application has been associated with biodiversity loss. Many studies have shown the potential to reduce the use of nitrogen without any impact on crop yield. Maintaining crop yield has been the goal, whereas crop quality has not been considered. In this paper, we investigate the effect of the level of soil organic carbon (SOC) and nitrogen fertiliser application on winter wheat (Triticum aestivum) yield and its quality. We show that the absence of nitrogen fertiliser decreased both yield and quality parameters of cereal grain. Quality parameters, such as protein and gluten contents, zeleny value, falling number and hardness were strongly positively influenced by nitrogen fertiliser application. The SOC level had no significant effect on these grain quality parameters. As a result, in the absence of nitrogen fertiliser, grain was not suitable for baking bread. We recommend that in the debate on the potential to limit the use of nitrogen in agricultural production, its impact on grain quality should be taken into consideration, especially at low levels of SOC.  相似文献   
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