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141.
Marianna Jagercikova Sophie Cornu Didier Bourlès Olivier Evrard Christine Hatté Jérôme Balesdent 《Journal of Soils and Sediments》2017,17(2):408-422
Purpose
Vertical transfer of solid matter in soils (bioturbation and translocation) is responsible for changes in soil properties over time through the redistribution of most of the soil constituents with depth. Such transfers are, however, still poorly quantified.Materials and methods
In this study, we examine matter transfer in four eutric Luvisols through an isotopic approach based on 137Cs, 210Pb(xs), and meteoric 10Be. These isotopes differ with respect to chemical behavior, input histories, and half-lives, which allows us to explore a large time range. Their vertical distributions were modeled by a diffusion-advection equation with depth-dependent parameters. We estimated a set of advection and diffusion coefficients able to simulate all isotope depth distributions and validated the resulting model by comparing the depth distribution of organic carbon (including 12/13C and 14C isotopes) and of the 0–2-μm particles with the data.Results and discussion
We showed that (i) the model satisfactorily reproduces the organic carbon, 13C, and 14C depth distributions, indicating that organic carbon content and age can be explained by transport without invoking depth-dependent decay rates; (ii) translocation partly explains the 0–2-μm particle accumulation in the Bt horizon; and (iii) estimates of diffusion coefficients that quantify the soil mixing rate by bioturbation are significantly higher for the studied plots than those obtained by ecological studies.Conclusions
This study presents a model capable of satisfactorily reproducing the isotopic profiles of several tracers and simulating the distribution of organic carbon and the translocation of 0–2-μm particles.142.
Vronique S. Lesage Brigitte Bouchet Larbi Rhazi Khalil Elmorjani Grard Branlard Didier Marion 《Journal of Cereal Science》2011,53(2):231-238
Wheat endosperm texture is correlated with one major locus, Ha, located on the short arm of chromosome 5D, which comprises several genes among which are two puroindoline genes, Pina and Pinb. In this study, we used two near-isogenic lines, the hard-textured line lacking Pina and the soft-textured line containing both Pina and Pinb wild-type genes. Hard and soft endosperms were observed at four kernel developmental stages, from 180 °Cd to 750 °Cd. Puroindolines were located within protein bodies at the onset of prolamin accumulation by transmission electron microscopy and immunolabelling. Ab initio modeling showed a closer structural relationship between puroindolines and 2S storage proteins from dicots than between puroindolines and other cysteine-rich wheat proteins, i.e. LTP and amylase inhibitors. Compared to the soft line, storage protein polymers in the hard line exhibited higher molecular mass (increase of from 6 to 93%) and polydispersity indices (increase of from 26 to 63%) over the course of the 4-year experiment. This suggests that puroindolines might impact the aggregation of storage proteins. Finally, these data pave the way for investigation of the role of protein–protein interactions in the texture of wheat endosperm. 相似文献
143.
西非Sudanian热带林地11个树种地上生物量异速生长预测 总被引:1,自引:0,他引:1
Louis Sawadogo Patrice Savadogo Daniel Tiveau Sidzabda Djibril Dayamba Didier Zida Yves Nouvellet Per Christer Oden Sita Guinko 《林业研究》2010,21(4):475-481
Allometric models are necessary for estimating biomass in terrestrial ecosystems. Generalized allometric relationship exists
for many tropical trees, but species- and region-specific models are often lacking. We developed species-specific allometric
models to predict aboveground biomass for 11 native tree species of the Sudanian savanna-woodlands. Diameters at the base
and at breast height, with species means ranging respectively from 11 to 28 cm and 9 to 19 cm, and the height of the trees
were used as predictor variables. Sampled trees spanned a wide range of sizes including the largest sizes these species can
reach. As a response variable, the biomass of the trees was obtained through destructive sampling of 4 754 trees during wood
harvesting. We used a stepwise multiple regression analysis with backward elimination procedure to develop models separately
predicting, total biomass of the trees, stem biomass, and biomass of branches and twigs. All species-specific regression models
relating biomass with measured tree dimensions were highly significant (p < 0.001). The biomass of branches and twigs was less predictable compared to stem biomass and total biomass, although their
models required fewer predictors and predictor interactions. The best-fit equations for total above-ground biomass and stem
biomass had R
2 > 0.70, except for the Acacia species; for branches including twig biomass, R2-values varied from 0.749 for Anogeissus leiocarpa to 0.183 for Acacia macrostachya. The use of these equations in estimating available biomass will avoid destructive sampling, and aid in planning for sustainable
use of these species. 相似文献
144.
Sidzabda Djibril Dayamba Patrice Savadogo Didier Zida Louis Sawadogo Daniel Tiveau Per Christer Oden 《林业研究》2010,21(4):445-450
Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried
out to assess the effects of season of burning, and different vertical probe positions on maximum fire temperature and temperature
residence time above 60°C which is considered lethal for plant tissues. Seasons of burning considered were: an early season
fire set at the beginning of the dry season (beginning of December), mid-season fire set at the peak of the dry season (mid-January),
and a late season fire at the end of the dry season (end of March). The effects of these fires on the germination of buried
seeds of three socio-economically valuable tree species were also examined. Results indicated significant differences in maximum
fire temperature and residence time with respect to season of burning and vertical probe position (p < 0.001). The highest and longest lasting temperatures were observed at 20 cm above ground during early fire and at the soil
surface during mid-season and late fires. This, in turn, affected germination responses of seeds buried at different soil
depths. Implications of these findings in the current management practices are discussed. 相似文献
145.
Q fever is a zoonotic disease caused by the ubiquitous pathogen Coxiella burnetii responsible for acute and chronic clinical manifestations. Farm animals and pets are the main reservoirs of infection, and transmission to human beings is mainly accomplished through inhalation of contaminated aerosols. This illness is associated with a wide clinical spectrum, from asymptomatic or mildly symptomatic seroconversion to fatal disease. In humans Q fever can manifest as an acute disease (mainly as a self-limited febrile illness, pneumonia, or hepatitis) or as a chronic disease (mainly endocarditis), especially in patients with previous valvulopathy and to a lesser extent in immunocompromised hosts and in pregnant women. In contrast in animals, Q fever is in most cases, strikingly asymptomatic. The definite diagnosis of Q fever is made based on a significant increase in serum antibody titers, the determination of which often requires considerable time, and therefore patients must be monitored for a certain period. The treatment is effective and well tolerated, but must be adapted to the acute or chronic pattern with the tetracyclines to be considered the mainstay of antibiotic therapy. Several actions have been proposed to prevent and reduce the animal and environmental contamination. Vaccination of animals in infected flocks, as well as in uninfected ones close to them, with an efficient vaccine can prevent abortions and shedding of the bacteria. 相似文献
146.
Gaby Van Galen DVM MSc DECEIM Helene Amory DVM PhD DECEIM Evita Busschers DVM DACVS Dominique Cassart DVM PhD Marco De Bruijn DVM DECEIM Vincent Gerber DVM PhD DECEIM John Keen DVM MSc DECEIM Laurence Lefere DVM Christel Marcillaud Pitel DVM Celia Marr DVM PhD DECEIM Jessica‐M. V. Müller DVM DECEIM Xavier Pineau DVM Claude Saegerman PhD Charlotte Sandersen DVM PhD DECEIM Didier Serteyn DVM PhD DECVAA Sara Torfs DVM Lucia Unger DVM Denis Verwilghen DVM MSc DECVS Dominique‐Marie Votion DVM PhD 《Journal of Veterinary Emergency and Critical Care》2010,20(5):528-532
Background – Atypical myopathy is an acute, severe rhabdomyolysis occurring in grazing horses. In the beginning of October 2009, a new outbreak occurred in several European countries. Geographic, demographic and clinical data of the reported cases in the month October 2009 are described. Key Findings – The survival rate in this outbreak was 25%. The most frequently observed clinical signs were congested mucous membranes, dyspnea, tachycardia, depression, weakness, stiffness, recumbency, trembling, sweating, and myoglobinuria. Nonsurvivors were significantly more likely to be recumbent than survivors. Prognostic factors, symptomatic treatment, and preventive measures are discussed. Significance – Differences were encountered during the described outbreak of atypical myopathy in October 2009 compared with previous outbreaks reported. Equine practitioners should be aware that previous epidemiological studies have shown that after a high prevalence in the autumn, new cases are likely to occur in the following spring. 相似文献
147.
Christian Hartmann Roland Poss Andrew D. Noble Apichart Jongskul Emmanuel Bourdon Didier Brunet Grgory Lesturgez 《Soil & Tillage Research》2008,99(2):245-253
In many coarse textured soils, limited root development and biomass production are attributed to adverse physical conditions in the subsoil. The current study was undertaken on an Arenic Acrisol located in Northeast Thailand (i) to assess whether subsoil physical characteristics influence crop rooting depth, and (ii) to compare the benefits associated with conventional tillage with that of localised subsoil loosening on crop performance and selected soil attributes. Control plots consisted of disk ploughing; the implemented treatments were conventional deep-ripping and localised slotting below the planting line. A crop rotation consisting of a legume followed by maize was established annually to assess the impact of these treatments on crop performance. In the control treatment, root development was restricted to the topsoil (0–20 cm) due to high subsoil bulk density (>1.6 Mg m−3). After deep-ripping, no improvement was observed in bulk density, rooting depth and in crop performance. The implementation of a slotting treatment systematically improved root development in the slotted subsoil, root impact frequency increasing from <0.2 to 0.6–0.8 (P = 0.01) despite no change in the bulk densities of the subsoil. This systematic improvement in root development could be explained by (i) reduced slumping that enable root development prior to recompaction and/or (ii) preferential drainage in the slot and therefore decreased resistance to root penetration. In a dry year maize yield was improved by 78% (P = 0.01); the deep-rooting legume Stylosanthes was tested only a wet year and its biomass production increased by >40% (P = 0.03). This study highlights the detrimental impact of subsoil compaction on root development and the potential role of slotting in coarse textured soils as a long-term management tool in addressing adverse subsoil physical characteristics that limit deep-rooting. 相似文献
148.
Didier ES Bowers L Stovall ME Kuebler D Mittleider D Brindley PJ Didier PJ 《Folia parasitologica》2005,52(1-2):173-181
Microsporidia are a cause of emerging and opportunistic infections in humans and animals. Although two drugs are currently being used to treat microsporidiosis, concerns exist that albendazole is only selective for inhibiting some species of microsporidia that infect mammals, and fumagillin appears to have been found to be toxic. During a limited sequence survey of the Vittaforma corneae genome, a partial gene encoding for the ParC topoisomerase IV subunit was identified. The purpose of this set of studies was to determine if fluoroquinolones, which target topoisomerase IV, exert activity against Encephalitozoon intestinalis and V. corneae in vitro, and whether these compounds could prolong survival of V. corneae-infected athymic mice. Fifteen fluoroquinolones were tested. Of these, norfloxacin and ofloxacin inhibited E. intestinalis replication by more than 70% compared with non-treated control cultures, while gatifloxacin, lomefloxacin, moxifloxacin, and nalidixic acid (sodium salt) inhibited both E. intestinalis and V. corneae by at least 60% at concentrations not toxic to the host cells. These drugs were tested in vivo also, where gatifloxacin, lomefloxacin, norfloxacin, and ofloxacin prolonged survival of V. corneae-infected athymic mice (P < 0.05), whereas moxifloxacin and nalidixic acid failed to prolong survival. Therefore, these results support continued studies for evaluating the efficacy of the fluoroquinolones for treating microsporidiosis and for characterizing the target(s) of these fluoroquinolones in the microsporidia. 相似文献
149.
Chetboul V Sampedrano CC Gouni V Concordet D Lamour T Ginesta J Nicolle AP Pouchelon JL Lefebvre HP 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2005,19(6):837-844
Right ventricular myocardial (RVM) motion is poorly documented. The objective of this study was to determine the variability of RVM velocities by tissue Doppler imaging (TDI) in healthy dogs (study 1), to analyze RVM motion in a large healthy canine population (study 2), and to compare the results with those obtained for the left ventricular free wall. Six healthy Beagle Dogs were monitored in study 1, and 64 healthy dogs of 14 different breeds were monitored in study 2. Velocities were recorded in 2 segments (basal and apical) of the right and left myocardial walls. In study 1, 36 TDI examinations were performed for 4 days, whereas a single TDI examination was performed on each dog in study 2. All velocity profiles included 1 positive systolic wave and 2 negative diastolic waves. The lowest intraday and interday coefficient of variation values of the right TDI variables were observed at the base (3.5-16.1%). The variability of the right apical velocities was much higher, with most coefficient of variation values > 15%. RVM velocities were higher in the basal than in the apical segments (P < .001) and were higher than the left velocities of the corresponding segment (P < .01). Body weight and breed had an effect on only a few right and left TDI variables. TDI provides a repeatable and reproducible method for evaluating basal RV function in the dog. These data also demonstrate the heterogeneity of the myocardial velocities between the left and the right ventricles and between the base and the apex. 相似文献
150.