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31.
The primary role of the avian bursa of Fabricius is to provide an essential microenvironment for B-lymphocytes to diversify their immunoglobulin genes by gene hyperconversion. Infectious bursal disease (IBD) vaccination using intermediate plus vaccine strains can temporarily deplete the bursal follicles and interrupt the normal B-cell development, which is generally followed by B-cell repopulation and histological regeneration. To find evidence that functional restoration of the bursa of Fabricius occurs in addition to the histological regeneration, we have analysed the chB1 gene expression, which indicates active bursal B-lymphocytes, and also the surface expression of a carbohydrate structure Lewis(x), a marker which identifies those bursal B-lymphocytes that are undergoing gene hyperconversion. In ovo vaccination with an immune complex vaccine (IBDV-BDA) caused transient bursal destruction in both the SPF and the maternally protected broiler groups with differences evident in the starting time, the severity and the duration of the effect. After the depletion phase, signs of histological regeneration appeared together with chB1- and Lewis(x) expression indicating that B-lymphocytes were functionally active and the bursa of Fabricius was serving again as an efficient primary lymphoid organ providing an appropriate microenvironment for B-cell development.  相似文献   
32.
Slaughter plants have been undergoing radical transformations in recent years due to the need to increase efficiency and incorporate new technologies for the improvement of the infrastructure, animal welfare, and product quality. The aim of this study was to assess the cattle welfare status during the unloading, lairage, stunning, bleeding and quantify bruising incidence at a commercial slaughter plant in the northwest of Mexico. We monitored 8,118 cattle during the unloading, lairage, stunning, bleeding, and carcass bruise incidence. Our results showed that in the unloading stage, 2% of the cattle vocalized, 5% were prodded with an electric goad, and 4% either slipped or fell. In the lairage stage, 12% of the animals vocalized, 80% prodded with an electric goad, and 8% of the animals slipped or fell. In the stunning stage, 10% of the animals vocalized, 67% prodded with an electric goad, and 15% of the animals slipped or fell. Ninety-five percent of the animals were stunned with a single shot, and 51% of the animals were effectively desensitized. Ninety-two percent of the carcasses had some type of bruise. Although the slaughter plant had adequate infrastructure and stringent operational standards, in all of the stages except unloading handling had an impact on the welfare of the animals being slaughtered.  相似文献   
33.
OBJECTIVE: To determine the effectiveness of administering multiple doses of phenylbutazone alone or a combination of phenylbutazone and flunixin meglumine to alleviate lameness in horses. ANIMALS: 29 adult horses with naturally occurring forelimb and hind limb lameness. PROCEDURES: Lameness evaluations were performed by use of kinematic evaluation while horses were trotting on a treadmill. Lameness evaluations were performed before and 12 hours after administration of 2 nonsteroidal anti-inflammatory drug (NSAID) treatment regimens. Phenylbutazone paste was administered at approximately 2.2 mg/kg, PO, every 12 hours for 5 days, or phenylbutazone paste was administered at approximately 2.2 mg/kg, PO, every 12 hours for 5 days in combination with flunixin meglumine administered at 1.1 mg/kg, IV, every 12 hours for 5 days. RESULTS: Alleviation of lameness was greater after administration of the combination of NSAIDs than after oral administration of phenylbutazone alone. Improvement in horses after a combination of NSAIDs did not completely mask lameness. Five horses did not improve after either NSAID treatment regimen. All posttreatment plasma concentrations of NSAIDs were less than those currently allowed by the United States Equestrian Federation Inc for a single NSAID. One horse administered the combination NSAID regimen died of acute necrotizing colitis during the study. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of a combination of NSAIDs at the dosages and intervals used in the study reported here alleviated the lameness condition more effectively than did oral administration of phenylbutazone alone. This may attract use of combinations of NSAIDs to increase performance despite potential toxic adverse effects.  相似文献   
34.
REASONS FOR PERFORMING STUDY: Subjective neurological evaluation in horses is prone to bias. An objective method of spinal ataxia detection is not subject to these limitations and could be of use in equine practice and research. HYPOTHESIS: Kinematic data in the walking horse can differentiate normal and spinal ataxic horses. METHODS: Twelve normal and 12 spinal ataxic horses were evaluated by kinematic analysis walking on a treadmill. Each body position signal was reduced to a scalar measure of uncertainty then fuzzy clustered into normal or ataxic groups. Correct classification percentage (CCP) was then calculated using membership values of each horse in the 2 groups. Subsequently, a guided search for measure combinations with high CCP was performed. RESULTS: Eight measures of body position resulted in CCP > or = 70%. Several combinations of 4-5 measures resulted in 100% CCP. All combinations with 100% CCP could be obtained with one body marker on the back measuring vertical and horizontal movement and one body marker each on the right fore- and hindlimb measuring vertical movement. CONCLUSIONS AND POTENTIAL RELEVANCE: Kinematic gait analysis using simple body marker combinations can be used objectively to detect spinal ataxia in horses.  相似文献   
35.
36.
Heart muscle viability following hypoxia: protective effect of acidosis   总被引:8,自引:0,他引:8  
The mechanical performance of hypoxic heart muscle is further depressed by an acid pH. In contrast to preparations at normal or alkaline pH. however, hypoxic preparations at acid pH do not develop contracture and exhibit full recovery of mechanical activity upon reoxygenation.  相似文献   
37.
In Central Spain hedgerows are an important component of the landscape although many have been lost due to landscape planning and reallotment programmes. Loss of hedgerows can produce changes in environmental conditions that can be especially critical in summer, corresponding with the dry period in Mediterranean ecosystems. In order to show the effects of hedgerow removal on summer Mediterranean environmental conditions in rural landscapes, this paper describes a comparison of some key environmental conditions between areas where hedgerows are still present, compared to areas where they have been removed. Through a two-way ANOVA, it was found that temperatures in the hedgerows were significantly different from those in the fields, whilst air temperatures beneath the hedgerows were lower, and steadier, than those of surrounding areas. When temperatures of the fields were compared to those sites where hedgerows had been removed, significant differences in temperatures were detected belowground and sometimes at soil surface level but not at higher levels. The levels of soil water content and organic carbon were higher where hedgerows were still in place. These differences indicate potentially negative environmental impacts due to hedgerow removal. The implications of hedgerow conservation for environmental protection and for cropland productivity are discussed.  相似文献   
38.

Vegetables in the tropics are grown continuously throughout the year due to the favorable climate. Unfortunately, leafy vegetables are often damaged because of slugs and snails. These mollusks and other herbivores cause different levels of defoliation to plants which can significantly impact their growth, production, and quality of the harvested product. A study was carried out in order to artificially simulate the effect of a loss in foliar area caused by these pests. The impact of severe artificial defoliation in spinach plants (Spinacia oleracea) was evaluated in Tunja, Colombia. Under greenhouse conditions and after transplanting, the plants had 75% of their leaf area removed. This procedure was repeated weekly on newly emerging leaves while a control group of plants was left intact. 71 days after transplanting, the plants were harvested, and the leaf area and dry weight of the plants were measured with which some allometric variables were calculated to express growth. Variables such as the number of leaves, plant height, total dry weight, relative growth ratio, leaf weight ratio (LWR), and root to shoot ratio (R:S) were unaffected by defoliation while leaf area, leaf area ratio (LAR), and specific leaf area (SLA) were reduced with the partial removal of the leaf area. The partial defoliation resulted in an increased partial biomass of the leaves. These results suggest that spinach plants have a moderate tolerance to partial defoliation.

  相似文献   
39.
Secondary metabolites (SMs), such as alkaloids and raffinose oligosaccharides (RFOs), play important roles in plant physiology. Although alkaloid and RFO phenotypic variation has been reported for yellow lupin (Lupinus luteus L.), most evaluations have used a reduced number of accessions; thus, limiting the understanding of accumulation patterns and variation ranges. The main goal of this research was to assess alkaloid and RFO content in a diverse L. luteus sample to understand possible SM accumulation patterns across this legume species. Eighteen yellow lupin accessions were analyzed using high performance thin layer chromatography to provide insights on seed and leaf RFO and alkaloid phenotypic variation. Co-dominant markers (170) were used to examine genetic relationships among L. luteus accessions and possible accumulation patterns across closely related genotypes. Significant differences were observed for seed and leaf RFOs. Total seed RFO accumulation ranged from 79.738 to 131.079 mg g?1. Raffinose, stachyose, and verbascose were observed in all genotypes’ seeds, but at different RFO concentrations. Raffinose was the only RFO detected in leaves (2.793–0.4224 mg g?1). Total alkaloid accumulation ranged from 0.22 to 15.12 and 0.00 to 8.007 mg g?1 for seeds and leaves, respectively. Lupinine, sparteine, and gramine were observed in seeds and leaves, and showed a wide range of variation. Neighbor-Joining (NJ) analysis showed an apparent pattern of seed alkaloid accumulation, most likely due to domestication events. However, high RFO accumulating accessions were scattered across the NJ tree. Alkaloid and RFO significant phenotypic variation will not only help to understand the roles of these SMs in L. luteus, but also to uncover the genetic basis behind their accumulation.  相似文献   
40.
In this investigation, the photocatalytic activity of α-Bi4V2O11 in the degradation of 2-naphthol under simulated solar light was evaluated. Bismuth vanadate α-Bi4V2O11 was synthesized by the solid-state reaction method and by co-precipitation in aqueous media, with the aim of comparing their performance in the photodegradation of the aromatic pollutant. The latter method (co-precipitation) has not been previously reported for the synthesis of α-Bi4V2O11. Structural evolution of the oxides precursors was determined by X-ray diffraction. Morphology and optical properties of the solids were analyzed by scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (UV-vis), respectively. The results showed that at 800 °C, only α-Bi4V2O11 was formed in both preparations. The SEM micrographs revealed that the powders were composed of agglomerates with sizes between 0.8–2 μm for those synthesized by co-precipitation and 2–10 μm for those obtained by solid-state reaction. The optical properties indicated that α-Bi4V2O11 was activated with visible light during the photocatalytic process. The photocatalytic degradation of 2-naphthol was largely influenced at basic pH, degrading 79% of the contaminant in 240 min, with the powder obtained by co-precipitation; meanwhile, for the solid-state preparation, the degradation reached only 55%.  相似文献   
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