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71.
Summary Uncooked white rice and cooked white rice were tested as vehicles for the V4 strain of oral Newcastle disease vaccine. The results of feeding experiments were evaluated by the measurement of haemagglutination inhibition antibodies against Newcastle disease virus. Little of the virus applied to uncooked white rice could be recovered, even immediately after mixing, whereas when the virus was applied to cooked white rice most of it could be recovered. In 4 separate experiments, chickens failed to respond serologically to vaccine supplied on uncooked white rice. In all of 4 experiments with cooked white rice, there were serological responses in vaccinated chickens, from 45% to 100% of the chickens developing titres sufficiently high to indicate protection against challenge with virulent virus. Development of haemagglutination inhibition antibodies in some control chickens indicated the ability of the vaccine virus for lateral spread or persistence in the environment.
Vacunacion Oral De Pollos Con La Cepa V4 Del Virus De La Enfermedad De Newcastle Utilizando Como Vehiculo Arroz Blanco Cocinado Y No Cocinado
Resumen Se utilizo arroz blanco sin cocinar y cocinado como vehículo para la vacuna oral con la cepa V4 de la enfermedad de Newcastle. Los resultados de los experimentos fueron evaluados mediante la determinación de los anticuerpos de inhibición-hemaglutinación contra el virus de la enfermedad de Newcastle. Poca cantidad del virus de la enfermedad de Newcastle pudo recuperarse en el arroz crudo, incluso inmediatamente despues de revolverlo, mientras que la mayoría del virus pudo recuperarse del arroz cocinado. En 4 experimentos separados, los pollos no respondieron serológicamente a la vacuna aplicada en arroz blanco crudo. En los 4 experimentos con arroz cocinado, se detectaron respuestas serológicas en los pollos vacunados; 45% a 100% de los pollos desarrollaron títulos suficientes como para resistir la descarga de virus virulento. El desarrollo de anticuerpos de inhibición-hemaglutinación en algunos de los pollos controles indicó la capacidad del virus vacunal para dispersarse lateralmente y persistir en el ambiente.
Vaccination Par Voie Orale De Poulets Avec La Souche V4 Du Virus De La Maladie De Newcastle Avec Comme Support Du Riz Blanc Cuit Et Du Riz Blanc Cru
Résumé Du riz blanc crû et du riz blanc cuit ont été testés en tant que supports de la souche de virus V4 du vaccin contre la maladie de Newcastle. Les résultats de ces expériences d'alimentation ont été évalués par la mesure des anticorps d'inhibition de l'hémagglutination du virus de la maladie de Newcastle.Seule une petite quantité du virus mélangé dans le riz blanc crû a pu être récupérée même immédiatement après le mélange. Par contre la majeur partie du virus a pu être récupérée lorsqu'il s'agissait du riz blanc cuit.Dans 4 expériences séparées, ils n'y avait pas de réponses sérologiques chez les poulets recevant du vaccin ajouté au riz blanc crû. Dans toutes les 4 expériences avec du riz blanc cuit, les réponses sérologiques ont été positives chez les poulets vaccines, 45p. 100 à 100p. 100 des poulets développant des titres suffisamment élevés pour démontrer une protection contre l'épreuve avec du virus virulent. Le développement des anticorps d'inhibition de l'hémagglutination chez quelques poulets témoins a montré la capacité de diffusion latérale ou la persistance dans l'environnement du virus.相似文献
72.
The increased number and complexity of the requirements for registration of agrochemicals are causing a steep rise in the costs of research and development and therefore in the price of agrochemicals. It now takes about 8–9 years for an agrochemical to be developed and marketed, at a probable cost of 10–20 million US dollars, and each of the individual tests required may cost up to US$ 500 000. A continuation of these trends would have serious consequences for industry, farmers, consumers and the developing countries. So far, the agrochemical industry has been able to continue to produce the new and improved materials necessary to combat changing pest attack: whether it can continue to do so may depend upon whether or not registration requirements are increased. Unnecessary requirements must be identified and eliminated, and any new demands must be fully justified in terms of the cost involved and of the ensuing benefits. However, if the search for greater safety were to be pushed to even greater lengths, so that costs exceed what the market will bear, the extra costs would have to be borne by the authorities and, ultimately, by the taxpayer. 相似文献
73.
Mannheimia (Pasteurella) haemolytica, the etiologic agent of bovine pneumonic mannheimiosis, produces an exotoxic leukotoxin. The leukotoxin (LktA) is a member of the RTX (repeats in toxin) family of bacterial cytolysins and is distinguished from other toxins by its unique target cell specificity to ruminant leukocytes occurring through binding to a specific receptor. We have demonstrated previously that the beta2 integrin LFA-1 is a receptor for LktA in bovine leukocytes and is involved in leukotoxin-induced biological effects. However the subunits within LFA-1 involved in binding to LktA, and post-binding signaling leading to cellular activation have not been well characterized. The purpose of our study was to pinpoint these precise subunits on bovine alveolar macrophages and to characterize their interaction with LktA. The results in this study indicate that although LktA can efficiently bind to the CD18 subunit of both LFA-1 and Mac-1, post-binding signaling events including elevation of intracellular calcium and CD18 tail phosphorylation are only observed through LFA-1. Furthermore, LktA also binds to the CD11a subunit of LFA-1. LktA binding to CD11a could be inhibited by a small molecule inhibitor of the I(inserted)-domain, the major ligand binding interface on CD11a. I-domain inhibition significantly blunts LktA-induced intracellular calcium elevation and tyrosine phosphorylation of the CD18 tail. Based on our results we suggest that LFA-1 serves as the functional leukotoxin receptor on bovine alveolar macrophages. 相似文献
74.
Zhang J Coulston RJ Jones ST Geng J Scherman OA Abell C 《Science (New York, N.Y.)》2012,335(6069):690-694
Although many techniques exist for preparing microcapsules, it is still challenging to fabricate them in an efficient and scalable process without compromising functionality and encapsulation efficiency. We demonstrated a simple one-step approach that exploits a versatile host-guest system and uses microfluidic droplets to generate porous microcapsules with easily customizable functionality. The capsules comprise a polymer-gold nanoparticle composite held together by cucurbit[8]uril ternary complexes. The dynamic yet highly stable micrometer-sized structures can be loaded in one step during capsule formation and are amenable to on-demand encapsulant release. The internal chemical environment can be probed with surface enhanced Raman spectroscopy. 相似文献
75.
A description of local pig feeding systems in village smallholder farms of Western Kenya 总被引:3,自引:3,他引:0
Mutua FK Dewey C Arimi S Ogara W Levy M Schelling E 《Tropical animal health and production》2012,44(6):1157-1162
We used face-to-face interviews to gather data on pig feeding practices in rural Busia District, Kenya. We visited 164 pig farms three times in the course of the study period. The pigs were weighed in kilograms during the visits. Feeds offered to pigs were described during the interviews. The most frequently fed feedstuffs were; ground maize or "ugali" (88%), kitchen leftovers (83%) and dried fish locally called "omena" (78%). Farmers provided pigs with water separately from the feeds. Sweet potatoes, "ugali" and cassava were available and could serve as good sources of energy for pigs in the district. Fruits and vegetables were also available and could potentially act as good sources of vitamins. Sweet potato vines, "omena" fish and slaughter blood were available and could provide pigs with proteins. The average daily gain (ADG) for pigs ≤ 5 months of age, pigs of 5.1-9.9 months of age and pigs of ≥ 10 months old was 94.5 (± 43), 127 (± 49.8) and 99 (± 92) g, respectively (p = 0.000). This study has outlined the different local pig feeds available in Busia district. We recommend two things: first, additional research on nutrient composition for the identified local feeds, and second, developing and validating simple local feed combinations that would achieve balanced local pig rations. 相似文献
76.
77.
Risk factors associated with occurrence of nematodes in free range pigs in Busia District,Kenya 总被引:1,自引:1,他引:0
Kagira JM Kanyari PN Githigia SM Maingi N Ng'ang'a JC Gachohi JM 《Tropical animal health and production》2012,44(3):657-664
Nematode infections are a serious constraint to pig production, especially where free range pig keeping is practiced. This
study investigated the epidemiology of nematodes in free range pigs in Busia District, Kenya. Three hundred and six pigs from
135 farms were sampled for faeces that were analysed for nematode eggs per gram (EPG) of faeces using the McMaster technique.
The nematode eggs were also identified to genus and species based on morphology. A questionnaire on risk factors was also
administered to the pig owners. The overall prevalence and mean nematode EPG were 84.2% and 2,355, respectively. The nematode
eggs were identified as those belonging to Oesophagostomum spp. (75%), Strongyloides ransomi (37%), Ascaris suum (18%), Metastrongylus spp. (11%), Trichuris suis (7%) and Physocephalus sexalatus (3%). The prevalence of nematodes was positively correlated (p < 0.05) with the amount of rainfall in the division of the pigs' origin (all nematodes except S. ransomi). The prevalence of nematodes was also associated with the age of the pigs. A lower burden of nematodes was associated (p < 0.05) with a history of deworming (A. suum) and the provision of night housing (S. ransomi and Metastrongylus spp.). In conclusion, this study has provided information on nematode infections and the associated risk factors for free
range pigs in Busia District, which can be used when implementing integrated control measures. 相似文献
78.
Graph-based analysis is a promising approach for analyzing the functional and structural connectivity of landscapes. In human-shaped
landscapes, species have become vulnerable to land degradation and connectivity loss between habitat patches. Movement across
the landscape is a key process for species survival that needs to be further investigated for heterogeneous human-dominated
landscapes. The common frog (Rana temporaria) was used as a case study to explore and provide a graph connectivity analysis framework that integrates habitat suitability
and dispersal responses to landscape permeability. The main habitat patches influencing habitat availability and connectivity
were highlighted by using the software Conefor Sensinode 2.2. One of the main advantages of the presented graph-theoretical
approach is its ability to provide a large choice of variables to be used based on the study’s assumptions and knowledge about
target species. Based on dispersal simulation modelling in potential suitable habitat corridors, three distinct patterns of
nodes connections of differing importance were revealed. These patterns are locally influenced by anthropogenic barriers,
landscape permeability, and habitat suitability. And they are affected by different suitability and availability gradients
to maximize the best possible settlement by the common frog within a terrestrial habitat continuum. The study determined the
key role of landscape-based approaches for identifying the “availability-suitability-connectivity” patterns from a local to
regional approach to provide an operational tool for landscape planning. 相似文献
79.
Samuel D. Fuhlendorf David M. Engle R. Dwayne Elmore Ryan F. Limb Terrence G. Bidwell 《Strength and Conditioning Journal》2012,65(6):579-589
This article examines the question of how well the rangeland management profession has served conservation of patterns and processes that support multiple ecosystem services. We examine the paradigms under which rangeland management operates and argue that our profession developed under the utilitarian paradigm with the primary goals of sustainable forage for livestock production. While optimization of multiple rangeland products and services has always been a consideration, a comprehensive set of principles have not be been developed to advance this concept. We argue that fire and grazing, often viewed as mere tools used for production goals, should rather be viewed as essential ecosystem processes. Rangeland management continues to operate under the utilitarian paradigm appropriate to societal values of the 20th century and by and large has failed to provide management guidance to reverse degradation of several highly valued ecosystem services. We support this argument with evidence that biodiversity has declined on rangelands in the past half century and that much of this decline is due to management goals that favor a narrow suite of species. The full suite of ecosystem services valued by society will only benefit by management for heterogeneity, which implies that there is no one goal for management and that landscape-level planning is crucial. Explicitly incorporating heterogeneity into state-and-transition models is an important advancement not yet achieved by our profession. We present new principles for rangeland management formed on the basis of conservation of pattern and process. While recognizing that many rangelands have significant deviations from historic plant communities and disturbance regimes, we suggest that management for conservation of pattern and process should focus on fire and grazing to the extent possible to promote a shifting mosaic across large landscapes that include patches that are highly variable in the amount of disturbance rather than the current goal of uniform moderate disturbance. 相似文献
80.
Barbara J. Daniels-Lake Robert K. Prange Jerzy Nowak Samuel K. Asiedu John R. Walsh 《American Journal of Potato Research》2005,82(5):389-397
Ethylene effectively inhibits sprouting of potatoes (Solanum tuberosum L.) during storage, but it often darkens fry color. The objective of the work described here was to determine if altering the concentration of ethylene applied would reduce the darkening while retaining adequate sprout inhibition. Trials were conducted over three consecutive years (1991–1992, 1992–1993, and 1993–1994). Tubers of cv Russet Burbank (ca 150–300 g) were stored at 9 C for 25 wk in closed chambers in a refrigerated room under continuous exposure to 0.4, 4, 40, or 400 µL L?1 ethylene gas delivered with the ventilation airstream (ca 0.5 air exchanges per h, for 6 h each day). Untreated control and chlorpropham-treated (CIPC) check tubers were stored under the same conditions but without ethylene supplementation. Sprout number, length, and biomass, fry color, loss of tuber mass, disease, and dry matter content were evaluated at 5-wk intervals. Dose-dependent effects (400>40>4>0.4 µL L?1) of ethylene on sprout growth and fry color were observed. The 400, 40, and 4 µL L?1 ethylene treatments inhibited sprout growth as effectively as CIPC, whereas in 0.4 µL L?1 ethylene sprouting was midway between CIPC and the untreated control. Sprout mass and maximum sprout length in all ethylene treatments were significantly lower (P<0.05) than in the untreated control. Compared with the initial value (57.3 Agtron reflectance units [ARu]), after 5 wk of storage fry color was up to 5 ARu darker in the ethylene treatments, but recovered steadily at the subsequent evaluation dates. At 25 wk of storage the fry color of tubers from the 40 and 4 µL L?1 ethylene treatments were, however, still darker than tubers stored with CIPC. Inhibition of sprout growth was slightly more effective in the 400 and 40 µL L?1 ethylene treatments than in 4 µL L?1, although there were no significant differences (P<0.01) in fry color between these treatments. In comparison with the other ethylene treatments, fry color in 0.4 µL L?1 ethylene was lighter, but inhibition of sprout growth was significantly (P<0.05) poorer. There were no differences in tuber disease incidence or dry matter content between the treatments. At 25 wk, the untreated tubers had ca 50% greater loss of tuber mass than any other treatment, attributable to their heavy sprouting. Loss of tuber mass in the ethylene treatments was not significantly different (P<0.001) from that in the CIPC treatment. 相似文献