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21.
Increasing demands for cost-effectiveness in surveillance for human health hazards from animal origins can be met by introducing risk-based principles. This e.g. implies targeting subpopulations with higher risk of infection compared to the whole population. Furthermore, historical data from surveillance can be collated and used to assess future risk of infection. To demonstrate the effectiveness of combining these two approaches, we used a model called “Discounting historical evidence”. It depends mainly on the annual risk of introduction (PIntro) and the surveillance system sensitivity (SSe) (ability to detect infection if present). The model implies simulations that reiterate for a number of years. For each year the output is updated with the confidence on absence in infection. Trichinella spiralis infection in pigs is used as an example. In Denmark, more than 20 million pigs are tested annually. Despite more than 70 years of testing no pigs have been found positive for Trichinella. Hence, PIntro is low. SSe can be estimated from the maximum number of infected carcasses expected under the specified design prevalence, and the sensitivity of the test applied. According to our assessment, the current prevalence of Trichinella in Danish pigs is less than one case per million, which we interpret as negligible risk. Based on this, a risk-based surveillance programme for Trichinella is designed that targets all out-door reared pigs as well as all sows and boars (current total 610,000 slaughtered annually). These subpopulations are judged to have higher risk of getting Trichinella. Again, SSe and PIntro are estimated and the model results show that risk-based surveillance can be applied without jeopardizing human health. Finally, we incorporate wildlife surveys and test quality assurance in the programme. The results of the simulation model were included in an application to the European Commission concerning Denmark's status as a region with negligible risk of Trichinella. In July 2007, the European Commission granted status as “negligible risk” to Danish pigs and pork.  相似文献   
22.
In this study, strength and frictional properties of pecan was determined as a functional of moisture content. A pecan was loaded between two parallel plates to determine the rupture force, deformation, power and firmness required to initiate pecan rupture and determined static and dynamic friction. The tests were carried out at five moisture contents of 5.23?%, 10.36?%, 15.78?%, 20.08?% and 25.42?% db and three axes (X, Y, Z). Physical characteristics of the pecan such as mass, dimensions (length, thickness and width), geometric mean diameter, sphericity, volume, and shell thickness were determined. The force required to initiate nut rupture decreased from 112.321 to 98.723 N, from 82.872 to 63,988 N and from 80.093 to 62.758 N for the length, suture and width orientations of loading with an increase in moisture content. The highest toughness (20.460 Jmm??3) was obtained at moisture content of 25.42?% db. The firmness decreased to a minimum value when moisture content was increased from 5.23 to 10.36?% db and later increased as moisture content was increased further from 10.36 to 25.42?% db. The static and dynamic coefficients of friction on various surfaces, namely, plywood, mild steel and galvanized metal also increased linearly with increase in moisture content. The plywood surface offered the maximum friction followed by mild metal and galvanized metal.  相似文献   
23.
Literature data about glycosides from sponges (Porifera, Demospongiae) are reviewed. Structural diversity, biological activities, taxonomic distribution and biological functions of these natural products are discussed.  相似文献   
24.
Different vegetal biomass resources such as Picea abies bark, Castanea sativa chestnuts shell and Asclepias syriaca plant were considered to provide a source of natural bioactive compounds, which can be properly used in several directions such as: plant growth regulators and amendments in bioremediation. Having in mind a complex processing biomass technology, these raw materials are used in a first step to separate bioactive compounds by an aqueous extraction. The obtained extracts containing polyphenols were tested in germination tests to evaluate their influence on cadmium bioaccumulation in oat plant (Avena sativa). It was observed that the mentioned extracts modulated cadmium bioaccumulation, photosynthesizing pigments biosynthesis, plant growth and its development depending on metal ion concentration (5, 12.5, 25 mg/L), and extracts composition determined by vegetal raw material and their total polyphenols content (130, 122, 114 mg/L related to gallic acid). FTIR spectra and histo-anatomical cross section of the roots certify that P. abies bark and A. syriaca plant extracts amendments stimulated cadmium bioaccumulation, promoting the translocation of heavy metals to the aerial part of the plant, meanwhile chestnuts shell extract reduced the mobility of cadmium determining in situ inactivation of heavy metal ions.  相似文献   
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Seven of nine colostrum‐deprived calves, free from infection with bovine virus diarrhoea virus (BVDV), were vaccinated with Rispoval? RS‐BVD on two occasions, 21 days apart, while the other two were kept as BVDV infection controls. The virus neutralizing (VN) serum antibodies induced by vaccination were tested for their ability to neutralize 18 European BVDV isolates, including laboratory reference strains and recent field isolates, both cytopathic and non‐cytopathic biotypes as well as genotypes I and II. The strains were isolated in Belgium, France, Germany and the United Kingdom. While there were large variations in the vaccine‐induced VN titres of the individual calves against all the strains, e.g. the titres against Osloss NCP, the European reference strain ranged from 1.7 to 6.7 (1 : log2), serum from each animal was capable of neutralizing between nine and all 18 of the strains tested. Nevertheless, from the results of this study, it can be concluded that in colostrum‐deprived BVDV seronegative calves, Rispoval? RS‐BVD can stimulate the production of VN antibodies capable of neutralizing a wide range of antigenically diverse European isolates of BVDV, including genotypes I and II.  相似文献   
27.
Asterosaponins are a class of steroid oligoglycosides isolated from starfish with characteristic structures and diverse biological activities. In this review, we have attempted to combine the most important data concerning asterosaponins and give a list of these secondary metabolites with their structural peculiarities. The purpose of this review is to provide a brief but as complete as possible principal information about their chemical structures, taxonomic distribution in the marine environment, distribution in different geographical areas and depths, some properties, biological activities, and functions. Some other rare steroid metabolites from starfish, closely related in structures and probably biogenesis to asterosaponins, are also discussed.  相似文献   
28.
Journal of Soils and Sediments - The sediment dynamics of (peri-)glacial catchments can be highly variable and complex. Understanding these dynamics and their underlying causes is not only of...  相似文献   
29.
Soil crusting and infiltration on steep slopes in northern Thailand   总被引:13,自引:0,他引:13  
Predicting the rate at which rain infiltrates on steep slopes is very uncertain. There is no consistent information in the literature. We have therefore related infiltrability to slope gradient under field conditions by experimenting on a gravelly loamy soil occupying the upper half of a cultivated convex hill in northern Thailand. Fifteen 1 m × 1 m plots with slope gradients ranging from 16 to 63% were established, and simulated rain was allowed to fall on them at controlled rates and for fixed times. We obtained the following results. The surface fell 0.4–7.2 mm due to compaction and soil loss. The proportions of crust (0–40%) and embedded gravel (10–60%), the runoff coefficient (0.05–0.78 mm mm?1), the mean sediment concentrations (0–5.6 g l?1), and soil detachment (10–313 g m?2) were more pronounced on the gentle slopes than on the steep ones. The steady final infiltration rate (1–107 mm hour?1) increased sharply with increasing slope gradient. Microaggregates tended to behave like sand and become tightly packed on gentle slopes (packing crust). These results suggest that the vertical component of kinetic energy, which is greater on gentle slopes, has a dominant role. Nevertheless, the differences in compaction and in sediment concentration could not be ascribed to the vertical component of kinetic energy alone. On steep slopes the horizontal component of the kinetic energy is transformed into shear stress, hampering the development of crusts so that water can still infiltrate. On steeper slopes, the water film was thinner, thereby limiting the role of splash. We conclude that the relationship between slope gradient and infiltrability depends on the nature of the soil and must be examined in the light of surface crusting processes.  相似文献   
30.
Ultrasonography and radiography are commonly used for staging of lymphoma in horses, however there is little published information on imaging characteristics for horses with confirmed disease. The purpose of this retrospective, case series study was to describe ultrasonographic and radiographic findings for a group of horses with a confirmed diagnosis of lymphoma. A total of 13 horses were sampled. Lymphadenopathy (8/13), peritoneal effusion (6/13), splenic (6/13), and hepatic (5/13) lesions were the most frequently identified. The predominant splenic and hepatic ultrasonographic lesions were hypoechoic nodules, organomegaly, and changes in echogenicity. Digestive tract lesions were detected in three horses and these included focal thickening and decreased echogenicity of the small (2/13) and large intestinal (2/13) wall. Thoracic lesions were predominantly pleural effusion (4/13), lymphadenopathy (4/13), and lung parenchymal changes (3/13). Enlarged lymph nodes were detected radiographically (4/13) and/or ultrasonographically (2/13) in the thorax and ultrasonographically in the abdomen (7/13) and in the caudal cervical region (4/13). Findings supported the use of abdominal and thoracic ultrasonography for lymphoma staging in horses. Ultrasound landmarks for localizing cecal and caudal deep cervical lymph nodes were also provided.  相似文献   
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