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21.
Daniel Keunecke Walter Sonderegger Karol Pereteanu Thomas Lüthi Peter Niemz 《Wood Science and Technology》2007,41(4):309-327
Despite the exceptional position of yew among the gymnosperms concerning its elastomechanical properties, no reference values
for its elastic constants apart from the longitudinal Young’s modulus have been available from literature so far. Hence, this
study’s objective was to determine the Young’s moduli E
L, E
R and E
T and the shear moduli G
LR, G
LT and G
RT of yew wood. For that purpose, we measured the ultrasound velocities of longitudinal and transversal waves applied to small
cubic specimens and derived the elastic constants from the results. The tests were carried out at varying wood moisture contents
and were applied to spruce specimens as well in order to put the results into perspective. Results indicate that E
L is in the same order of magnitude for both species, which means that a high-density wood species like yew does not inevitably
have to have a high longitudinal Young’s modulus. For the transverse Young’s moduli of yew, however, we obtained 1.5–2 times,
for the shear moduli even 3–6 times higher values compared to spruce. The variation of moisture content primarily revealed
differences between both species concerning the shear modulus of the RT plane. We concluded that anatomical features such
as the microfibril angle, the high ray percentage and presumably the large amount of extractives must fulfil important functions
for the extraordinary elastomechanical behaviour of yew wood which still has to be investigated in subsequent micromechanical
studies. 相似文献
22.
23.
The long-term study objective was to determine the suitability of selected species of genus Pinus (Pinus sylvestris, Pinus nigra and Pinus mugo) for use as bioindicators of environmental pollution. In these experiments a new methodology of evaluation of mitotic abnormalities was established and its potential for common use tested. The study confirmed three species of genus Pinus as suitable bioindicators. The results also indicate that trees may show adaptive changes in response to severe pollution stress. 相似文献
24.
25.
OBJECTIVE: To determine whether administration of the nonsteroidal anti-inflammatory drugs meloxicam or carprofen to healthy dogs that were subsequently anesthetized and subjected to painful electrical stimulation has adverse effects on renal function as measured by glomerular filtration rate (GFR) and evaluation of serum concentrations of urea and creatinine. ANIMALS: 6 male and 6 female healthy young-adult Beagles. PROCEDURE: A study was conducted in accordance with a randomized crossover Latin-square design. One of 3 treatments (saline [0.9% NaCl] solution, 0.2 mg of meloxicam/kg, or 4.0 mg of carprofen/kg) was administered i.v. 1 hour before anesthesia was induced by use of drugs in accordance with a standard anesthetic protocol (butorphanol tartrate and acepromazine maleate as preanesthetic medications, ketamine hydrochloride and diazepam for induction, and maintenance with isoflurane). Anesthetized dogs were subjected to intermittent electrical stimulation for 30 minutes. Direct, mean arterial blood pressure; heart rate; and respiratory rate were monitored. End-tidal isoflurane concentration was maintained at 1.5 times the minimum alveolar concentration. The GFR, as measured by plasma clearance of 99mTc-diethylenetriaminepentaacetic acid, and serum concentrations of serum and creatinine were determined 24 hours after induction of anesthesia. RESULTS: Neither meloxicam nor carprofen significantly affected GFR or serum concentrations of urea and creatinine, compared with values for the saline treatment. CONCLUSIONS AND CLINICAL RELEVANCE: When administered 1 hour before onset of anesthesia and painful electrical stimulation, meloxicam or carprofen did not cause clinically important alterations of renal function in young healthy dogs. 相似文献
26.
Shane W. Bateman DVM DVSc. Karol A. Mathews DVM DVSc Anthony C.G. Abrams-Ogg DVM DVSc 《Journal of Veterinary Emergency and Critical Care》1998,8(1):29-45
Diagnosis of Disseminated Intravascular coagulation (DIC) is controversial in both human and veterinary medicine. This article reviews the available literature in human and veterinary medicine regarding the etiology, pathophysiology, and diagnosis of DIC with emphasis on the diagnosis of DIC in dogs. Controversy surrounding the diagnosis of DIC arises from the complex nature of the disease itself, in addition to the absence of a consensus strategy for laboratory testing. The available literature indicates that dogs diagnosed with DIC possessed various hemostatic function testing abnormalities, typically possessed an underlying disease that predisposed to DIC, but may or may not have had clinically identifiable hemorrhage or thrombosis. Additionally, the hemostatic function testing utilized in diagnosis is not uniform. Generalizations about the usefulness of individual assays or diagnostic strategies cannot be formulated because of the marked diversity of the types of cases studied, as well as the small number of cases reported in the literature. (Vet Emerg & Crit Care, 1998; 8: 29–45) 相似文献
27.
28.
RA McKENZIE KG REICHMANN CK DIMMOCK PJ DUNSTER JO TWIST 《Australian veterinary journal》1988,65(6):165-167
Two calves given a mean of 16.1 g and 16.4 g ripe Castanospermum australe seeds/kg body weight daily for 13 and 16 days respectively developed haemorrhagic gastroenteritis. The first calf died. The second calf had mild myocardial degeneration and necrosis and mild nephrosis at necropsy. Two calves given a mean of 16.8 g unripe C. australe seeds/kg body weight daily for 18 days remained clinically normal and had mild gastritis at necropsy. The activity of alpha-glucosidase was reduced in the mononuclear cells of peripheral blood and in skeletal muscle. This was attributed to the presence of the indolizidine alkaloid, castanospermine, in the seeds. The toxin causing the gastroenteritis and other lesions is unknown. 相似文献
29.
Naturally occurring and experimental Stachys arvensis (staggerweed) toxicity in lambs in New Zealand
Stachys arvensis (staggerweed) is a common, widely distributed weed of cultivated and waste land with the potential to intoxicate sheep. Two naturally occurring outbreaks of suspected staggerweed toxicity in the lower North Island were investigated. Affected lambs had been recently moved onto staggerweed-contaminated Brassica spp. crops. In total, 150/1,200 (13%) lambs developed hindlimb paresis, a fine generalised muscular tremor, and hunched posture. When forced to move, many became recumbent. Most lambs recovered within 48 h of removal from staggerweed, although a few developed clinical signs again when transported 2–3 weeks later. Grossly, affected lambs had large amounts of staggerweed plant material and seeds within the rumen. Histopathology showed mild, multifocal degeneration of the white matter tracts of the central nervous system (CNS), most commonly in the ventral funiculi of the spinal cord, and acute, mild to moderate, multifocal degeneration of skeletal muscles. Creatine kinase (CK) activity in serum was mildly to markedly elevated in affected lambs. In a feeding trial, ten 10-month-old Romney lambs were randomly assigned to equal treatment and control groups. Treated lambs were drenched with a liquid extract of staggerweed once daily for 7 days. Three of five treated lambs developed mild exercise intolerance, and 1/5 displayed mild paresis of the hindlimbs, slightly crouched hindlimb stance, and shortened gait, on days 6 and 7. Histologically, 4/5 treated lambs had degeneration in white matter tracts of the CNS, indistinguishable from those seen in the lambs in the outbreak, and in 1/5 lambs there was scattered regeneration of skeletal muscle. CK activity in serum in treated lambs was not significantly higher than that in control lambs. None of the control lambs developed significant clinical signs, histological changes or increases in CK activity in serum. The clinical signs and lesions observed in both the outbreaks and feeding trial were similar to those previously described in studies in Australia, with the exception that myodegeneration was more prominent in the outbreaks in New Zealand. Further characterisation of the pathogenesis of staggerweed toxicity and its potential role as a food safety hazard will be facilitated through identification of the toxic principle(s). 相似文献
30.
Karol PJ 《Science (New York, N.Y.)》1984,226(4681):1425-1427
Interaction mean free paths are calculated for projectile fragments from relativistic heavy-ion interactions in emulsions and plastic. There are important discrepancies between emulsion results and those from other techniques. "Anomalous" secondaries (anomalons) may prove to be interpretable by conventional nuclear physics: short mean free paths may be due to convoys of collinear light fragments from peripheral interactions (for example, with neutrons) or from low-excitation particle-unbound fragments that decay in flight. 相似文献