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111.
Reynardt Erasmus Johnnie van den Berg Peet Jansen van Rensburg Hannalene du Plessis 《Pest management science》2023,79(5):1860-1867
BACKGROUND
Tuta absoluta (Lepidoptera: Gelechiidae) is difficult to control by means of foliar insecticides, partly because of the endophytic feeding behavior of its larvae. The biopesticide spinosad is applied as a foliar spray for control of T. absoluta and has systemic properties when applied as a soil drench to the growing medium of tomato plants. The aims of this study were to determine the: (i) instar-dependent tolerance of larvae to spinosad; (ii) efficacy of spinosad drench application for the control of larvae; (iii) residual period of systemic activity of spinosad in leaves and fruit after drenching; and (iv) effect of spinosad drenching on tomato plant growth parameters.RESULTS
The estimated LC50 value (Lethal Concentration at which 50% of the larvae died) differed between instars. The LC50 for second-instar larvae (0.41 ppm) to spinosad was significantly lower than that for third- (0.64 ppm) and fourth-instar (0.63 ppm) larvae. The LC80 value (Concentration at which 80% of the larvae died) for fourth-instar larvae (2.48 ppm) was 2.6- and 1.7-fold higher than that for the second- and third-instar larvae, respectively. The spinosad concentration recorded in leaves at 25 days after treatment (DAT; 0.26 μg g−1) was significantly lower than that in leaves sampled at 3, 10 and 15 DAT. High larval mortalities were, however, recorded for the duration of the experiment, which lasted 25 days (equivalent to one T. absoluta generation).CONCLUSION
Systemic spinosad effectively controlled T. absoluta larvae over a prolonged period. However, drenching this insecticide violates the recommendation of the Insecticide Resistance Action Committee to avoid treating consecutive insect generations with the same mode of action and can therefore result in the evolution of insecticide resistance. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. 相似文献112.
Morphology of the Pelvis and Hind Limb of the Red Panda (Ailurus fulgens) Evidenced by Gross Osteology,Radiography and Computed Tomography 下载免费PDF全文
M. Makungu W. M. du Plessis H. B. Groenewald M. Barrows K. N. Koeppel 《Anatomia, histologia, embryologia》2015,44(6):410-421
The red panda (Ailurus fulgens) is a quadrupedal arboreal animal primarily distributed in the Himalayas and southern China. It is a species commonly kept in zoological collections. This study was carried out to describe the morphology of the pelvis and hind limb of the red panda evidenced by gross osteology, radiography and computed tomography as a reference for clinical use and identification of skeletons. Radiography of the pelvis and right hind limb was performed in nine and seven animals, respectively. Radiographic findings were correlated with bone specimens from three adult animals. Computed tomography of the torso and hind limb was performed in one animal. The pelvic bone had a wide ventromedial surface of the ilium. The trochlea of the femur was wide and shallow. The patella was similar to that seen in feline species. The medial fabella was not seen radiographically in any animal. The cochlea grooves of the tibia were shallow with a poorly defined intermediate ridge. The trochlea of the talus was shallow and presented with an almost flattened medial ridge. The tarsal sesamoid bone was always present. The lateral process of the base of the fifth metatarsal (MT) bone was directed laterally. The MT bones were widely spaced. The morphology of the pelvis and hind limb of the red panda indicated flexibility of the pelvis and hind limb joints as an adaptation to an arboreal quadrupedal lifestyle. 相似文献
113.
Efficacy of a novel formulation of metaflumizone plus amitraz for the treatment of sarcoptic mange in dogs 总被引:1,自引:0,他引:1
A novel spot-on formulation containing metaflumizone plus amitraz (ProMeris/ProMeris Duo for Dogs, Fort Dodge Animal Health, Overland Park, KS) was evaluated for efficacy against sarcoptic mange mites in naturally infested dogs. Sixteen dogs were allocated to two equal groups and were housed individually. Eight of the dogs were treated topically with metaflumizone plus amitraz at the proposed minimum dose rate (20mg/kg of each of metaflumizone and amitraz, at a dose volume of 0.133ml/kg) on Days 0 and 28. The other eight were treated with metaflumizone plus amitraz at the proposed minimum dose rate on Days 0, 14, 28 and 42. To enumerate Sarcoptes scabiei mites, skin scrapings were taken on each of Days 2, 14, 28, 42 and 56. Clinical signs of mange and the extent of sarcoptic lesions were evaluated on each dog when scrapings were made. Evaluation of the efficacy of the treatment was based on the absence of mites supported by the absence of clinical signs associated with canine sarcoptic mange. Treatment with metaflumizone plus amitraz at the minimum proposed dose rate at monthly (two treatments) or two-weekly (four treatments) intervals resulted in a rapid reduction of mites and improved clinical signs. The overall cure rates at Day 56, based on zero mite counts and/or resolution of clinical signs were 75% and 83% of dogs for the monthly and two-weekly regimens, respectively. 相似文献
114.
115.
The effects of intensive site management treatments at establishment on the production ecology of a stand of Eucalyptus grandis were evaluated in South Africa. Treatments mimicked common operational practices in the region, and included slash removal, slash conservation, slash burning, topsoil disturbance through mechanised harvesting and fertilisation. We calculated the carbon distribution in the standing biomass from allometric relationships. Fine root turnover and litterfall measurements were determined using sequential coring techniques and litter traps, respectively, and this data was used to construct a full model of biomass allocation among stand components. Differences in nutrient availability to young trees, brought about by the most extreme site management treatments, produced several small but significant changes in the elements of the system's production ecology: Absorbed photosynthetically active radiation (APAR) increased from 210 to 247 Mmol photons ha−1 over the 3-year monitoring period, apparent canopy quantum efficiency (α; defined as gross primary production per unit of APAR) from 0.026 to 0.029 mol C (mol photon)−1, and the fraction of carbon allocated to stem wood from 32.7% to 35.6% of net primary production. The magnitudes of these individual responses collectively described the increase in net primary productivity and the Type 1 timber volume response obtained. The biggest changes occurred in APAR, in contrast to published studies from higher rainfall environments where differences in nutrient availability caused greater changes in α than in APAR. 相似文献
116.
Shannon M. Carmody Kevin M. King Cynthia M. Ocamb Bart A. Fraaije Jon S. West Lindsey J. du Toit 《Plant pathology》2020,69(3):518-537
Light leaf spot, caused by the ascomycete Pyrenopeziza brassicae, is an established disease of Brassicaceae in the United Kingdom (UK), continental Europe, and Oceania (OC, including New Zealand and Australia). The disease was reported in North America (NA) for the first time in 2014 on Brassica spp. in the Willamette Valley of western Oregon, followed by detection in Brassica juncea cover crops and on Brassica rapa weeds in northwestern Washington in 2016. Preliminary DNA sequence data and field observations suggest that isolates of the pathogen present in NA might be distinct from those in the UK, continental Europe, and OC. Comparisons of isolates from these regions using genetic (multilocus sequence analysis, MAT gene sequences, and rep-PCR DNA fingerprinting), pathogenic (B. rapa inoculation studies), biological (sexual compatibility), and morphological (colony and conidial morphology) analyses demonstrated two genetically distinct evolutionary lineages. Lineage 1 comprised isolates from the UK, continental Europe, and OC, and included the P. brassicae type specimen. Lineage 2 contained the NA isolates associated with recent disease outbreaks in the Pacific Northwest region of the USA. Symptoms caused by isolates of the two lineages on B. rapa and B. juncea differed, and therefore “chlorotic leaf spot” is proposed for the disease caused by Lineage 2 isolates of P. brassicae. Isolates of the two lineages differed in genetic diversity as well as sensitivity to the fungicides carbendazim and prothioconazole. 相似文献
117.
118.
Tillage effects,soil quality and production potential of kikuyu–ryegrass pastures in South Africa 下载免费PDF全文
P. A. Swanepoel J. Habig C. C. du Preez H. A. Snyman P. R. Botha 《Grass and Forage Science》2017,72(2):308-321
Soil quality of tillage systems receives much attention worldwide, although few studies attempt to link soil quality to yield. Partial least‐squares regression analysis is a suitable method to construct predictive models around plural, highly collinear factors, such as soil quality and its effects on yield. This study aimed at identifying the soil quality properties which best model pasture herbage yield by relating soil quality indicators with variations in yield as a result of soil disturbance caused by tillage. The study was conducted on kikuyu (Pennisetum clandestinum) over‐sown with annual ryegrass (Lolium multiflorum) using different tillage methods. Tillage methods involved over‐sowing kikuyu with ryegrass using a minimum‐tillage seed drill, eradication of kikuyu with herbicide and ryegrass sown with a minimum‐tillage planter, shallow and deep disturbance, and a control. Most changes in soil quality indicators as a result of soil tillage were observed shortly after tillage and occurred mostly at the 0–100 mm soil layer. Few of these effects were still visible 420 d after tillage. Microbiological indicators changed most in response to the treatments, but unlike the chemical and physical indicators, microbiological indicators have no causal link to pasture production. The contribution of individual soil quality indicators to variance in pasture productivity could not be isolated and should thus be seen as complex processes which affect yield. Although mechanisms of how some soil quality indicators affect yield is clear, more research is required to determine mechanisms of how a combination of multiple soil quality indicators affects yield. 相似文献
119.
抗白粉病高产小麦新品种南农9918 总被引:14,自引:0,他引:14
将现代生物技术与常规育种技术相结合,以本所育成的高抗白粉病普通小麦-簇毛表6VS/6AL易位系与丰产适应性好的扬麦158杂交,再用扬麦158回交,通过连续多代抗白粉病鉴定、外源易位染色体分子、细胞遗传学追踪和农艺性状鉴定,选育出高抗白粉病的高产新品系南农99-18。经2年区域试验和1年生产试验,该品系均表现高抗白粉病,具有穗大,粒重的特点,较对照品种扬麦158增产1.88%-2.20%。2002年8月通过江苏省品种审定委员会审定,正式定名为南农9918。该品种较好地综合了簇毛麦高抗白粉病及扬表158的丰产适应性,适于长江中下游麦区种植。 相似文献
120.
Mendelson JR Lips KR Gagliardo RW Rabb GB Collins JP Diffendorfer JE Daszak P Ibáñez D R Zippel KC Lawson DP Wright KM Stuart SN Gascon C da Silva HR Burrowes PA Joglar RL La Marca E Lötters S du Preez LH Weldon C Hyatt A Rodriguez-Mahecha JV Hunt S Robertson H Lock B Raxworthy CJ Frost DR Lacy RC Alford RA Campbell JA Parra-Olea G Bolaños F Domingo JJ Halliday T Murphy JB Wake MH Coloma LA Kuzmin SL Price MS Howell KM Lau M Pethiyagoda R Boone M Lannoo MJ Blaustein AR Dobson A Griffiths RA 《Science (New York, N.Y.)》2006,313(5783):48