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111.
112.
Prolonged summer droughts due to climate change are expected for this century, but little is known about the effects of drying and wetting on biogenic trace‐gas fluxes of forest soils. Here, the response of CO2, N2O, NO, and CH4 fluxes from temperate forest soils towards drying–wetting events has been investigated, using undisturbed soil columns from a Norway spruce forest in the “Fichtelgebirge”, Germany. Two different types of soil columns have been used for this study to quantify the contribution of organic and mineral horizons to the total fluxes: (1) organic horizons (O) and (2) organic and mineral soil horizons (O+M). Three drying–wetting treatments with different rewetting intensities (8, 20, and 50 mm of irrigation d–1) have been compared to a constantly moist control to estimate the influence of rainfall intensity under identical drying conditions and constant temperature (+15°C). Drought significantly reduced CO2, N2O, and NO fluxes in most cycles. Following rewetting, CO2 fluxes quickly recovered back to control level in the O columns but remained significantly reduced in the O+M columns with total CO2 fluxes from the drying–wetting treatment ranging approx. 80% of control fluxes. Fluxes of N2O and NO remained significantly reduced in both O and O+M columns even after rewetting, with cumulative fluxes from drying–wetting treatments ranging between 20% and 90% of the control fluxes, depending on gas and cycle. Fluxes of CH4 were small in all treatments and seem to play no significant role in this soil. No evidence for the release of additional gas fluxes due to drying–wetting was found. The intensity of rewetting had no significant effect on the CO2, N2O, NO, and CH4 fluxes, suggesting that the length of the drought period is more important for the emission of these gases. We can therefore not confirm earlier findings that fluxes of CO2, N2O, and NO during wetting of dry soil exceed the fluxes of constantly moist soil. 相似文献
113.
Antibiotic resistance in Escherichia coli and Enterococcus spp. isolates from commercial broiler chickens receiving growth-promoting doses of bacitracin or virginiamycin 下载免费PDF全文
Alexandre Thibodeau Sylvain Quessy Evelyne Guvremont Alain Houde Edward Topp Moussa Sory Diarra Ann Letellier 《Canadian journal of veterinary research》2008,72(2):129-136
Antibacterial agents such as zinc bacitracin (ZB) and virginiamycin (VG) are used as growth promoting agents (GP) in broiler chicken production. The objective of this study was to evaluate the effect of the use of ZB and VG on the emergence of antibacterial resistance in a commercial broiler chicken farm. Three trials were conducted using 3 different diets: one without antibacterial agents, one containing VG, and one with ZB. Escherichia coli and Enterococcus spp. strains were isolated and tested for their susceptibility to various antibacterial agents. The occurrence of the resistance genes vatD, ermB, and bcrR in Enterococcus spp. isolates was determined by polymerase chain reaction (PCR). Comparative quantification of vatD and bcrR genes in total deoxyribonucleic acid (DNA) extracts from litter was done by SYBR Green Real-Time PCR (QPCR). Escherichia coli and Enterococcus spp. isolates from diet groups had different levels of resistance to various antibacterial agents over time. These GPs did not select for specific antibacterial agent resistance (AAR) in Enterococcus spp. The use of GPs seemed to lower the percentage of E. coli isolates resistant to some antibacterial agents. The presence of the bcrR gene could not explain all resistant phenotypes to ZB. Genes other than vatD and ermB might be involved in the resistance to VG in Enterococcus spp. Use of GPs was not associated with presence of the bcrR gene in DNA extracts from litter, but use of VG was associated with vatD presence. 相似文献
114.
115.
Objective To study the dexamethasone (DXM) concentration at different time points in various compartments of the canine eye following topical application of DXM-21-isonicotinate and oxytetracycline hydrochloride
Animals studied Thirty dogs to be euthanized for reasons not related to this study were selected and their ocular health status evaluated. Selected animals were treated with DXM-oxytetracycline ointment and euthanized after 6, 11 or 16 h.
Procedure The concentration of DXM was determined in the following compartments of the eye: third eyelid, cornea, aqueous humor, iris, lens, vitreous body and choroid/retina. The DXM concentration in the eye was measured by radioimmunoassay. The applied amount of DXM was 0.04 mg in 0.2 mL ointment. Dogs were treated once with Corti Biciron® eye ointment (DXM-21-isonicotinate and oxytetracycline hydrochloride, S & K Pharma, Perl, Germany) and were euthanized 6, 11 and 16 h after treatment.
Results At 6 h following topical application the mean DXM concentration was highest in the anterior structures of the eye (third eyelid: 18 ng/g, cornea: 36 ng/g). The concentration in the posterior structures was below detection level. A decreased DXM concentration in the anterior structures was measured 11 and 16 h after treatment.
Conclusion It could be demonstrated that therapeutically relevant concentrations of DXM after a single topical administration are only achieved in anterior structures of the eye. A dosing interval of 6–11 h is recommended to achieve therapeutic drug concentration in those structures. The posterior structures of the eye are not reached by topical administration. 相似文献
Animals studied Thirty dogs to be euthanized for reasons not related to this study were selected and their ocular health status evaluated. Selected animals were treated with DXM-oxytetracycline ointment and euthanized after 6, 11 or 16 h.
Procedure The concentration of DXM was determined in the following compartments of the eye: third eyelid, cornea, aqueous humor, iris, lens, vitreous body and choroid/retina. The DXM concentration in the eye was measured by radioimmunoassay. The applied amount of DXM was 0.04 mg in 0.2 mL ointment. Dogs were treated once with Corti Biciron
Results At 6 h following topical application the mean DXM concentration was highest in the anterior structures of the eye (third eyelid: 18 ng/g, cornea: 36 ng/g). The concentration in the posterior structures was below detection level. A decreased DXM concentration in the anterior structures was measured 11 and 16 h after treatment.
Conclusion It could be demonstrated that therapeutically relevant concentrations of DXM after a single topical administration are only achieved in anterior structures of the eye. A dosing interval of 6–11 h is recommended to achieve therapeutic drug concentration in those structures. The posterior structures of the eye are not reached by topical administration. 相似文献
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117.
Zusammenfassung Es wurde untersucht, welche Faktoren die Empfindlichkeit von ?pfeln für Druckstellen unmittelbar nach der CA/ULO-Lagerung
(CA = Controlled Atmosphere, ULO = Ultra Low Oxygen) beeinflussen.
Früchte der Sorten ‘Golden Delicious’ und ‘Jonagold’ wurden nach der CA/ULO-Lagerung für fünf Tage bei vier verschiedenen
Nachlagerungsbedingungen (kühl in und ohne Folienbeutel, warm in und ohne Folienbeutel) aufbewahrt. Direkt nach der Auslagerung,
ein Tag und fünf Tage sp?ter wurden die ?pfel mittels zwei Apparaturen unterschiedlichen Belastungen ausgesetzt, um Druckstellen
zu erzeugen. Weitere gemessene Parameter waren die Fruchtfleischfestigkeit, der Gelbwert, der Gewichtsverlust, der Zellbruchpunkt
und die Schalenbruchfestigkeit.
Das Ausma? der Druckstellen nahm mit steigender Belastung der Früchte zu. Die warm gelagerten Früchte zeigten mit zunehmender
Zeit der Nachlagerung eine geringere Druckstellenempfindlichkeit. Die kühl gelagerten Früchte der Sorte ‘Golden Delicious’
zeigten eine Zunahme der Druckstellenempfindlichkeit im Verlauf der Nachlagerung, die der Sorte ‘Jonagold’ eine Abnahme oder
keine Ver?nderung.
Ein Zusammenhang zwischen der Druckstellenempfindlichkeit und der Fruchtfleischfestigkeit, dem Zellbruchpunkt oder der Schalenbruchfestigkeit
wurde nicht festgestellt.
相似文献
118.
From 2001 to 2005 the influence of the dwarfed apple rootstocks M 9 (clone: Burgmer 984), Fleuren 56, Supporter 1, P 16, P 22, J-TE-F, J-TE-E and M 27 on growth, yield and fruit size of the apple variety ‘Boskoop, Herr’ was investigated on the locations Auweiler, Dresden-Pillnitz, Osnabrück and Wurzen in Germany. All rootstocks induced a less vegetative growth as the rootstock M 9. In comparison with M 9 the crown volume of the trees ranged from 93% (Supporter 1) to 48% (P 22). The highest yield potential showed the rootstock P 16. Her specific yield (kg/m3) was 41% higher than the specific yield of M 9. J-TE-F produced the lowest specific yield. 相似文献
119.
Fruits of European plum (Prunus domestica L.) show high rates of transpiration. Consequently, they are highly perishable fruit. In the present study, the potential of an edible coating (Versasheen®-based with sorbitol as plasticizer) to improve storage life and keeping quality was evaluated on fruit of the plum cultivars ‘Jojo’ and ‘Tophit plus’. Plums were picked at commercial harvest date and stored at 2?±?0.5?°C (90?±?2% rh) for up to 28?d plus 2?d at 20?°C to simulate shelf life. Every seventh day, plums were analysed for transpiration, colour changes and laser light backscattering imaging (LLBI) at a wavelength of 785?nm to non-destructively investigate variations in quality properties of plums. Finally, fruit flesh firmness, soluble solids content, and titratable acidity were determined destructively. Results indicated that coating of fruit of both cultivars increased their surface resistance against water vapour transfer resulting in lower transpiration rates and thus lower mass losses compared to controls. Consequently, coating of fruit considerably delayed the decrease in flesh firmness. Moreover, edible coating retarded the increase of FWHM785 in coated plums. In this context, FWHM785 proved as a rapid and non-destructive tool to monitor changes in mechanical properties in heavily coloured plums. Results highlight that edible coatings successfully extend post-harvest life of plums. 相似文献
120.