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1.
Soil and human health: a review   总被引:24,自引:0,他引:24  
Soil can affect human health in several ways leading either to specific diseases or to more general ill health. Some illnesses are caused by people's eating soil (geophagia), or by their inhaling it which can lead to malignancy if the soil contains asbestiform minerals; pathogens in the soil can lead to tetanus and infestations of hookworm, and particles may enter the body through abrasions and cause a form of elephantiasis. Radon from the soil is implicated in some cancers, and poorly drained soil has been linked recently with infant mortality. Most examples of ill health associated with the soil are caused by concentrations of elements in food or water that are either deficient or toxic. These elements include aluminium, arsenic, cadmium, copper, fluorine, iodine, lead, selenium, thallium and zinc. Their concentrations might reflect the natural condition of the soil, or the effects of people's actions, such as pollution. In isolated subsistence communities that grow their own food, distinct relations between elements and the aetiology of diseases can be identified. Examples include Keshan disease caused by selenium deficiency, and itai-itai disease caused by excess cadmium. Some of the relations between soil and health are uncertain and the causes putative, and they require further research to validate them. They include the association of heart disease with poor acid soil, as in the glaciated regions of northern Europe and the coastal plain of the eastern United States of America. Even for well-defined relations it is evident that many are more complex than was originally thought, however, and greater understanding will require multidisciplinary investigation.  相似文献   
2.
A 9-year-old male Appenzeller mountain dog had progressive severe ataxia and central vestibular syndrome that was localized clinically to the brain stem. The cerebrospinal fluid characteristics were suggestive of hemorrhage into the subarachnoid space. On computed tomography (CT), hyperattenuating masses were found in the left lateral ventricle extending into the cerebrum, and another involving the cerebellum and brainstem. The hyperattenuation of the masses in noncontrast images and the absence of contrast enhancement were consistent with hemorrhage. The dog underwent euthanasia. A metastatic hemangiosarcoma in the brain, causing acute bleeding in the left lateral ventricle and the brainstem, was found. A solitary mass in the left myocardium was thought to be the primary site. CT characteristics of intracranial hemorrhage are reviewed.  相似文献   
3.
The isotope 15N was used to study the rate of exchange between unlabelled NH4-hydrobiotite and labelled solution NH4. Most of the isotopic dilution occurred within 10 minutes of adding the solution to the solid, but even after 13 days less mineral-NH4 had exchanged with isotope than was removed by several extractions with KC1 solution. NH4 remaining in the mineral after extraction with KC1, conventionally named ‘fixed ammonium’, contained some isotope which was sorbed without release of unlabelled NH4; the fixed ammonium was, therefore, not isotopically exchangeable. The sorption was shown to result from incomplete ammonium saturation of hydrobiotite, isotope slowly replacing interlayer cations trapped by lattice collapse. The rate of sorption was initially controlled by a temperature-dependent diffusion process for which the activation energies were between 9 and 13 kcal/ mole. In the later stages of the reaction the rate became progressively slower than predicted by the diffusion equation, and analysis of the kinetics suggested that, ultimately, exchange of cations at the sorption sites was the rate-limiting process.  相似文献   
4.
Disjunctive kriging is a technique for estimating values of spatially distributed random variables by combining data non-linearly and with minimum variance. Data are transformed using Hermite polynomials to a normal distribution, and the resultant transformation is assumed to produce a stationary bivariate normal distribution for all pairs of data. Conditional probabilities that the true values exceed or are less than a specified critical threshold can then be calculated. For soil survey both the estimated values of soil properties and their associated probabilities can be mapped isarithmically as aids to decisions on land management.
The technique is described and illustrated from two case studies. The pH, exchangeable potassium and available phosphorus are mapped over 77 ha of the Broom's Barn Farm, and in the eastern Border Region of Scotland the available copper and cobalt in the topsoil are mapped. The estimates are similar to those obtained by simple (linear) kriging. The conditional probabilities were estimated for values falling short of the minimum recommended thresholds, and maps of them showed where farmers would be advised to remedy or forestall deficiencies in lime and plant nutrients and to take prophylactic measures for their livestock.  相似文献   
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Phenothiazine and thiabendazole were studied for their ability to antagonize venoconstriction induced by ergonovine, and the biogenic amine serotonin, in the isolated dorsal pedal vein of cattle. The two compounds are commercially available, approved for usage in cattle and have been reported to reverse some of the toxic effects associated with the intake of Acremonium coenophialum-infested fescue forage by cattle. Neither compound had any antagonistic activity against venoconstriction induced by ergonovine. However, thiabendazole did have some activity against venoconstriction induced by serotonin. Ergot alkaloids are known to cause venoconstriction through effects on biogenic amine receptors, including serotonergic receptors, and since thiabendazole has anti-serotonin activity, part of the reported beneficial effects of thiabendazole in alleviating fescue toxicity may be due to the anti-serotonin activity of the drug. Further work is needed to determine if phenothiazine and thiabendazole have any effect on other types of alkaloids that are present in A. coenophialum-infested fescue.  相似文献   
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In an attempt to reduce postoperative incontinence associated with excisional prostatectomy and the recurrence of prostatic disease after less radical surgeries, a new technique for subtotal prostatectomy was developed using an ultrasonic surgical aspirator. During laparotomy, a longitudinal incision was made in the ventral surface of each lobe of the prostate gland. Biopsies for histology and culture were taken. Through the ventral incisions, the ultrasonic surgical aspirator  相似文献   
9.
Determining the extent of dispersal in exploited marine fishes is essential for understanding their population dynamics and optimising management. The West Australian dhufish, Glaucosoma hebraicum, is a highly sought‐after, large and long‐lived reef‐dwelling species, endemic to south‐western Australia. Stock assessments indicate that this indicator species is overexploited. The fishery is managed using a zone‐based system, which implicitly assumes a high degree of demographic independence among zones. While tagging studies indicate limited movement of adult G. hebraicum, there is no understanding of the spatial scale of dispersal of its larvae and thus the true extent of interdependence of management zones. We analysed 13 microsatellite DNA loci to characterise the extent of gene flow, and conducted particle tracking simulations to model larval transport in this species. Genetic data demonstrated that some local recruitment was likely, but that on a broad scale gene flow between the management zones was extensive, and the entire fishery represents a single genetic stock. Hydrodynamic modelling predicted that the majority of dhufish larvae recruit from within the management zone where they are spawned, and that inter‐annual variation in current velocities has limited effect on the extent of larval transport. Because management zones are likely to be largely independent in terms of both larval and adult recruitment, heavy localised fishing pressure has the potential to reduce the abundance and reproductive capacity of this species in highly fished areas, but it should have limited impact on neutral genetic diversity.  相似文献   
10.
Objective— To report long-term outcome after arthroscopic removal of fragmentation of the extensor process of the distal phalanx in horses.
Study Design— Case series.
Animals— Adult horses (n=13).
Methods— Medical records (2003–2004) of horses that had arthroscopic debridement of fragmentation of the extensor process of the distal phalanx were reviewed. Inclusion criteria included: lameness localized to the foot, fragmentation of the extensor process of the distal phalanx debrided arthroscopically, and a follow-up period of ≥4 years.
Results— Of the 13 horses, lameness was resolved in 11 (85%) initially but distal interphalangeal joint pain recurred in 2 (15%) within 1 year of surgery. Three (23%) other horses were retired because of lameness at other sites during the follow-up period resulting in 46% (6/13) being not lame and in full work after 4 years. Substantial changes were identified at surgery in the contralateral joint of 7 horses, even when fragments were only present unilaterally.
Conclusions— Arthroscopic debridement of fragmentation of the extensor process of the forelimb distal phalanx has a good short-term prognosis for resolution of lameness and return to work but a more guarded prognosis for long-term soundness.
Clinical Relevance— These results allow for more accurate prognostication preoperatively and may support early debridement of fragmentation of the extensor process of the distal phalanx.  相似文献   
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