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71.
72.
Low‐molecular‐weight organic acids with one or more carboxylic groups are ubiquitous. In soils, they can originate from leaching of plants, litter decomposition, plant‐roots exudation, and microbial activity. Their presence in the soil may favor the formation of soluble organo‐metallic complexes that improve the transport of Zn, Cu, Fe, and Mn to plant‐root surfaces via diffusion. The current study sought to determine if some of the organic acids (OA) in soils and a cover‐crop residue influence the diffusive flux (DF) of Zn, Cu, Mn, and Fe. Two OA were added to two Oxisols (Typic Haplustox): a clayey Dark Red Latosol (DRL) and a sandy‐loam Red Yellow Latosol (RYL). Acetic and citric acid were added to achieve concentrations of 0, 250, 500, 1000, and 2000 mmol (m3 soil)–1. The effect of adding plant material (pearl millet) on the soil DF of the cationic micronutrients was also determined. Soil diffusive flux was evaluated by incubating positively charged and negatively charged exchange‐resin membranes with the soil in PVC diffusion chambers for 15 d. Desorption of Zn, Cu, Fe, Mn, and OA from the resins was performed with 0.5 mol l–1 HCl. The results demonstrated that the DF of the cationic micronutrients increased with the addition of organic acid. The DF of Zn and Mn occurred mostly towards the cationic resin, whereas the diffusive flux of Cu and Fe occurred mostly towards the anionic resin. Apparently, the dissolution of oxides and/or complexation of micronutrients adsorbed to the solid phase or in the soil solution contributed to the obtained results. Citric acid was more efficient than acetic acid in maintaining a larger DF value for Zn, Cu, and Fe. The addition of millet plant material to the soil increased the DF in the following order: Mn > Cu > Fe > Zn; Mn moved towards the cationic resin, and the other micronutrients moved towards the anionic resin. These findings suggest that organic compounds play an important role in the short‐distance transport of cationic micronutrients in highly weathered soils.  相似文献   
73.
The susceptibility of capybaras exposed to foot-and-mouth disease (FMD) virus by the intramuscular route and the rodents' close coexistence with cattle in FMD endemic ecosystems suggested that the species might play an important role in the virus' survival in the field.In the present study 2 capybaras and 2 cattle were exposed by contact to a capybara inoculated intramuscularly with FMD virus. Both pairs of exposed animals were then used as a contact source with another 2 cattle and 2 capybaras, respectively. All the animals became infected prior to the appearance of clinical lesions in the respective donor animals and developed generalized FMD clinical lesions. Specific neutralizing antibodies and antibodies to virus-infection-associated antigen (VIA) were also developed.Virus was isolated from feces and from throat swabs of 1 of the capybaras up to 17, but not at 23 days post-contact. Virus was isolated from the remaining animals up to 7–14 days post-contact.The results indicate that these rodents might transmit virus over long distances due to their migratory movements, but probably do not act as natural virus reservoirs.  相似文献   
74.
The zoonotic characteristic of Mycobacterium avium subsp. avium (MAA) represents a veterinary and economic problem in infected pigs. In this study, we analysed cell-mediated immunity six months after experimental infection by measuring interferon-γ (IFN-γ) production and by performing lymphocyte transformation tests after in vitro re-stimulation with the MAA-derived antigen. At the same time, IFN-γ-producing cells were characterised by flow cytometry. In MAA-infected animals, the production of IFN-γ increased in response to the MAA antigen in the blood, spleen and mesenteric lymph nodes. Similarly, a positive antigen-driven response was detected by the proliferation assay. In contrast, IFN-γ production and proliferation was undetectable after stimulation with the MAA antigen in uninfected control animals. These results indicate that both methods can be used for the identification of individual MAA-infected pigs. Using flow cytometry, we found that double-positive CD4(+)CD8(+) lymphocytes were the major T lymphocyte subset producing IFN-γ after in vitro re-stimulation.  相似文献   
75.
ABSTRACT: Vaccination of chickens has become routine practice in Asian countries in which H5N1 highly pathogenic avian influenza (HPAI) is endemically present. This mainly applies to layer and breeder flocks, but broilers are usually left unvaccinated. Here we investigate whether vaccination is able to reduce HPAI H5N1 virus transmission among broiler chickens. Four sets of experiments were carried out, each consisting of 22 replicate trials containing a pair of birds. Experiments 1-3 were carried out with four-week-old birds that were unvaccinated, and vaccinated at day 1 or at day 10 of age. Experiment 4 was carried out with unvaccinated day-old broiler chicks. One chicken in each trial was inoculated with H5N1 HPAI virus. One chicken in each trial was inoculated with virus. The course of the infection chain was monitored by serological analysis, and by virus isolation performed on tracheal and cloacal swabs. The analyses were based on a stochastic SEIR model using a Bayesian inferential framework. When inoculation was carried out at the 28th day of life, transmission was efficient in unvaccinated birds, and in birds vaccinated at first or tenth day of life. In these experiments estimates of the latent period (~1.0 day), infectious period (~3.3 days), and transmission rate parameter (~1.4 per day) were similar, as were estimates of the reproduction number (~4) and generation interval (~1.4 day). Transmission was significantly less efficient in unvaccinated chickens when inoculation was carried out on the first day of life. These results show that vaccination of broiler chickens does not reduce transmission, and suggest that this may be due to the interference of maternal immunity.  相似文献   
76.
Ellagic acid (EA), a plant-derived polyphenol, exhibits antioxidant, anti-inflammatory, and gastroprotective effects. Its gastroprotective mechanisms have not been fully elucidated nor have its effects on chronic ulcer previously been described. Toward these ends, the antiulcer activities of EA were evaluated in acute (ethanol and indomethacin) and chronic (acetic acid) ulcer models in Wistar rats. In this study, oral administration of EA significantly prevented the gastric ulceration caused by ethanol, indomethacin, and acetic acid treatments. Its gastroprotective mechanism in ethanol-induced ulcer were partly due to intensification in the endogenous production of nitric oxide, an antioxidant effect by replenishing depletion of endogenous nonprotein sulfhydryls and attenuation of tumor necrosis factor-α increase, whereas in indomethacin ulcer, it is partly due to a reduction in the plasma level of leukotriene B(4). In acetic acid ulcer, promotion of ulcer-healing effects was partly due to attenuation of the elevated levels of the inflammatory cytokines TNF-α, interferon-γ, and interleukins-4 and -6. These findings suggest that ellagic acid exerts its antiulcer activity by strengthening the defensive factors and attenuating the offensive factors.  相似文献   
77.
Summary At present, the collection of cultivated plants comprises in Czechoslovakia 40883 cultivars of field, vegetables and fruits, vine grape and ornamental plants. The collection has been located in the Research Institute of Crop Production, Praha-Ruzyn, which also renders the central coordination, and in 17 specialized Research Institutes and Breeding Stations which are responsible for investigation, maintenance, exploration of the collections of special crops. Continual research has assumed since 1951 when former collections of different research stations (amounting only 6000 cultivars) were united.The first efforts to collect cultivars by the different research and breeding stations were started in the SSR already at the beginning of this century. A part of the then collections coming from different research and breeding stations has been conserved up to present time and represents, together with later collected cultivars, a valuable gene pool of 2000 cultivars of Czechoslovak origin. The original Czechoslovak cultivars are represented by selections, lines or clones from land-races (wheat, barley, oat, legumes, flax, hop, self-pollinated fodders and vegetables), or populations (maize, oil plants, fodders vegetables and ornamental plants). The major part of the collection is represented by Czechoslovak cultivars coming from combination crossing.The old cultivars of vine grape, fruits and ornamental plants have been maintained since the beginning of this century in old plantations of the research institutes or they are registred by them. Also cultivars of wheat (Czech red wheats, Czech alternate wheats, South-Moravian awnless and awned wheats, Slovak awned wheats) and of barley (spring malting Haná barley, Haná is territory in middle Moravia) come from the same period. The oldest native as well as foreign cultivars of other agricultural crops originate from thirties being conserved at different degree of breeding intensity at the time of their cultivation.
Die Erhaltung der Landsorten von Kulturpflanzen in der SSR
Zusammenfassung Gegenwärtig umfaßt die Kollektion in der SSR 40883 Sorten von Feldfrüchten, Gemüse, Obst, Weinreben und Zierpflanzen. Die Kollektion befindet sich im Forschungsinstitut für Pflanzenbau Prag-Ruzyn, das für die zentrale Koordinierung zuständig ist, sowie in 17 spezialisierten Forschungsinstituten und Zuchtstationen, die für die Untersuchung und Erhaltung der Kollektionen spezieller Kulturpflanzen verantwortlich sind. Kontinuierliche wissenschaftliche Untersuchungen begannen im Jahr 1951, als die früheren Kollektionen verschiedener Forschungsstationen (nur etwa 6000 Sorten) vereinigt wurden.In der SSR bemühten sich bereits zu Beginn dieses Jahrhunderts verschiedene Forschungs- und Zuchtstationen um die Sammlung von Sorten. Ein Teil der damaligen, aus verschiedenen Forschungs- und Zuchtstationen stammenden Sammlungen wurde bis zur Gegenwart erhalten und stellt, zusammen mit später gesammelten Sorten, einen wertvollen Genpool von 2000 Sorten tschechoslowakischer Herkunft dar. Die tschechoslowakischen Originalsorten sind durch Linien oder Klone von Landsorten (Weizen, Gerste, Hafer, Leguminosen, Lein, Hopfen, selbstbefruchtende Futterpflanzen und Gemüse) oder Populationen (Mais, Ölfrüchte, Futterpflanzen, Gemüse und Zierpflanzen) vertreten. Den größten Teil der Kollektion bilden tschechoslowakische Sorten, die durch Kombinationszüchtimg entstanden sind.Die alten Sorten von Weinrebe, Obst und Zierpflanzen werden seit Beginn, dieses Jahrhunderts in alten Anpflanzungen von wissenschaftlichen Instituten erhalten und durch diese registriert. Auch Sorten von Weizen (böhmische Rotweizen, böhmische Wechselweizen, südmährische grannenlose und begrannte Weizen, slowakische begrannte Weizen) und Gerste (Sommerbraugerste Hanna; die Hanna ist ein Gebiet in Mittelmähren) stammen aus dem gleichen Zeitraum. Die ältesten einheimischen und ausländischen Sorten anderer landwirtschaftlicher Kulturpflanzen, die aus den dreißiger Jahren stammen, werden entsprechend dem Stand der Züchtung z. Z. ihres Anbaues erhalten.

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  相似文献   
78.
ABSTRACT

A greenhouse experiment was performed to evaluate macronutrients and boron deficiencies on vitexin bioproduction by sweet passion fruit leaves. Sand irrigated with nutrient solution was used as substrate in a complete randomized design, with eight treatments: 1) complete, 2) nitrogen-deficient(-N), 3) phosphorus-deficient(-P), 4) potassium-deficient(-K), 5) calcium-deficient(-Ca), 6) magnesium-deficient(-Mg), 7) sulfur-deficient(-S), and 8) boron-deficient(-B). After thirty days, the fourth fully expanded leaves were harvested. Under deficiency treatments, leaf dry matter concentrations of N, P, K, Ca, Mg, S, and B were 52, 53, 62, 76, 69, 31, and 80% lower than in complete treatment, respectively. Nitrogen, P, and K deficiency increased vitexin leaf concentration by 46, 16, and 18%, although Ca and B deficiencies decreased vitexin concentration by 22 and 33%, respectively, when compared to complete treatment. Magnesium and S deficiencies had no significant effect on vitexin concentration. In complete treatment, the concentration of nutrients and vitexin, in leaf dry matter were: 43.4 g kg? 1 of N, 2.47 g kg? 1 of P, 27.4 g kg? 1 of K, 15.6 g kg? 1 of Ca, 3.8 g kg? 1 of Mg, 5.28 g kg? 1 of S, 64 mg kg? 1 of B, and 5.57 mg kg? 1 of vitexin.  相似文献   
79.
The efficiency of diets with the inclusion of Spirulina for Siberian sturgeon weaning has been tested. Three isoproteic and isoenergetic diets were formulated with an increasing level of Indian strain Spirulina (SP 40%, SP 50% and SP 60%); the diets were tested against a control diet without microalgae. The results show that Spirulina inclusion improves growth and that an inclusion level of 50% gave the greatest growth rate, a better favourable feed conversion rate and the highest protein efficiency. The fatty acid composition of fillets showed differences between the experimental and control diets: an increase in the Spirulina level induces increases in palmitic and linoleic acids and a decrease in the myristic acid. The control diet was characterized by high levels of eicosapentaenoic and docosahexaenoic acids. At the end of the experiment, statistical differences appeared in the fatty acid profile of the sturgeon fillet, mainly concerning high content of monounsaturated fatty acid and polyunsaturated fatty acid in the sturgeon fillets. If the problems related to the high production costs are solved, Spirulina could prove a good partial substitute fish meal.  相似文献   
80.
A Carassius auratus complex from an artificial wetland in the Morava River basin is composed of triploid females. Based on body depth, sampled females could be divided into two groups: (i) high-dorsal (42.5% of standard length); and (ii) low-dorsal (36.1% of standard length). Both groups differed also in number of gill rakers (50.2 versus 45.4, respectively). In concordance with morphological differences, genetic analysis proved the existence of two haplotypes in examined individuals. The first haplotype is bound to the high-dorsal form with higher number of gill rakers. This is the most frequent haplotype in populations of the C. a gibelio form in the Czech Republic. The second haplotype is characteristic of the low-dorsal form with a lower number of gill rakers. This haplotype is close to haplotypes described in the C. a. langsdorfii form, which is known from Japan. and its occurrence within haplotypes specified in European territory is sporadic.  相似文献   
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