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通过2种常用化肥对固氮鱼腥藻(Anabaena azotica Ley),球胞鱼腥藻(Anabaena sphaerica Born),多变鱼腥藻(Anabaena variabilio Kutzing)影响的研究。结果表明,尿素和碳酸氢铵在低浓度(20mg/L以下)表现为促进,当浓度为80mg/L时,则显著抑制其种群生长;且高浓度时,尿素和碳酸氢铵对3种藻产生较强影响,处理96h时的EC50值分别为54.0,67.0,85.7mg/L及73.7,63.1,92.2mg/L。 相似文献
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Scarcity of simple and reliable methods of estimating soil organic carbon (SOC) turnover and lack of data from long-term experiments make it difficult to estimate attainable soil C sequestration in tropical improved fallows. Testing and validating existing and widely used SOC models would help to determine attainable C storage in fallows. The Rothamsted C (RothC) model, therefore, was tested using empirical data from improved fallows at Msekera in eastern Zambia. This study (i) determined the effects of nitrogen fixing tree (NFT) species on aboveground organic C inputs to the soil and SOC stocks, (ii) estimated annual net organic C inputs to the soil using the RothC, and (iii) tested the performance of RothC model using empirical data from improved fallows. Soil samples (0–20 cm) were collected from coppicing and non-coppicing fallow experiments in October 2002 for determination of SOC by LECO CHN-1000 analyser. Data on surface litter, maize and weed biomasses, and on weather, were supplied by the Zambia/ICRAF Agroforestry Project. Measured SOC stocks to 20 cm depth ranged from 32.2 to 37.8 t ha−1 in coppicing fallows and 29.5 to 30.1 t ha−1 in non-coppicing fallows compared to 22.2–26.2 t ha−1 in maize monoculture systems. Coppicing fallows accumulated more SOC (680–1150 g m−2 year−1) than non-coppicing fallows (410–789 g m−2 year−1). While treatments with NFTs accumulated more SOC than NFT-free systems, SOC stocks increased with increasing tree biomass production and tree rotation. For food security and C sequestration, coppicing fallows are a potentially viable option. 相似文献
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本研究以东祁连山高寒草地常见的7种禾本科牧草为材料,通过分离培养的方法研究了其根际细菌的数量和分布,重点研究了其有固氮作用的细菌数量和分布。结果发现,7种植物根际均存在大量的细菌,总数在2.50×106~17.07×106 cfu/g,不同植物根际细菌的数量和分布不同,以高原早熟禾根际细菌数量最多,冰草和赖草根际细菌最少,其余禾草居中;根际固氮菌的数量和分布也因牧草种类不同而不同。7种供试植物根际分离到固氮菌201株。且细菌和PGPR菌株的数量均呈现“根系表面(RP)>根际土壤(RS)>根内(HP)”的分布趋势,表现出强烈的根际效应。 相似文献
78.
Kristell Hergoualc'h Jean-Michel Harmand Patrice Cannavo Ute Skiba Robert Oliver Catherine Hnault 《Soil biology & biochemistry》2009,41(11):2343-2355
Soil moisture and gaseous N-flux (N2O, N2) dynamics in Costa Rican coffee plantations were successively simulated using a mechanistic model (PASTIS) and two process-based models (NGAS and NOE). Two fertilized (250 kg N ha−1 y−1) coffee plantations were considered, namely a monoculture and a system shaded by the N2 fixing legume species Inga densiflora. In situ N2O fluxes were previously measured in these plantations. NGAS and NOE used specific microbial activities for the soils. To parameterize NGAS, we estimated N mineralization via in situ incubations and the contribution of heterotrophic soil respiration to total soil respiration. Potential denitrification rates and the proportion of denitrified N emitted as N2O were measured in the laboratory to define the values of NOE parameters, as well as nitrification rates and related N2O production rates for parameterizing both models. Soil moisture and both NGAS and NOE N2O fluxes were best modelled on an hourly time step. Soil moisture dynamics were satisfactorily simulated by PASTIS. Simulated N2O fluxes by both NGAS and NOE (3.2 and 2.1 kg N ha−1 y−1 for NGAS; 7.1 and 3.7 kg N ha−1 y−1 for NOE, for the monoculture and shaded plantations respectively) were within a factor of about 2 of the observed annual fluxes (4.3 and 5.8 kg N ha−1 y−1, for the monoculture and shaded plantations respectively). Statistical indicators of association and coincidence between simulated and measured values were satisfactory for both models. Nevertheless, the two models differed greatly in describing the nitrification and denitrification processes. Some of the algorithms in the model NGAS were apparently not applicable to these tropical acidic Andosols. Therefore, more detailed information about microbial processes in different agroecosystems would be needed, notably if process-oriented models were to be used for testing strategies for mitigating N2O emissions. 相似文献
79.
氮磷钾对红花草固氮根瘤菌生长及种植后土壤肥力的影响 总被引:2,自引:0,他引:2
为了发展有机水稻,以红花草-有机水稻轮作培肥水田土壤肥力,研究氮、磷、钾对红花草固氮根瘤菌生长及种植后土壤肥力的影响,为红花草的合理种植、培肥地力提供依据。2012—2013 2年稻后茬种植红花草,过冬前分别单独施用不同用量的氮肥、磷肥、钾肥,以不施肥为对照,探讨不同肥料不同用量对红花草产草量、固氮根瘤菌数量、固氮根瘤菌重量的影响及种植后的土壤肥力变化状况。研究结果表明:红花草前期补施氮、磷、钾,氮素对红花草的影响较大,在施氮75 kg/hm2(N 46%)时,产草量最高,固氮根瘤菌数量最多,固氮根瘤菌重量大;种植后土壤全氮变化表现为不同施氮量增幅随肥料用量增加而增加,施磷、施钾各处理增幅随肥料用量增加而先降后升;土壤速效磷变化为施氮、施磷各处理增幅随肥料用量增加而增加,施钾各处理增幅趋势表现不明显;土壤速效钾变化表现为施氮、施磷各处理增幅变化趋势是随肥料用量增加先升后降,在施氮150 kg/hm2(N 46%)、施磷300 kg/hm2(P2O5 12%)时,土壤速效钾增幅达最大;土壤有机质变化表现为增幅随肥料用量增加而增加。所以,种植红花草,前期适当补施氮、磷、钾,可以提高红花草产草量,有效提高土壤肥力。 相似文献
80.
为了研究氮素转化菌对茶树根际土壤微生态环境的影响,本试验以山东泰安2年生茶树根际土壤为研究对象,设置枯草芽孢杆菌(T1)和褐球固氮菌(T2)两个接种处理,以不接种为对照(CK)。采用培养计数法与末端限制性片段长度多态性技术(T-RFLP),测定不同时期根际土壤中细菌、真菌、放线菌、氨化细菌、固氮菌、硝化细菌的数量及接种后微生物多样性的变化。同时测定接种后土壤中养分含量的变化。结果表明,接种60βd后T1和T2处理细菌数量显著高于CK,但对真菌及放线菌的影响不显著。整个试验过程氨化细菌和固氮菌数量高于CK,氨化细菌以T1处理最多,固氮菌以T2处理最多,硝化细菌数量始终是CK显著高于T1和T2处理。基于T-RFLP图谱分析,与对照组相比,菌剂组均增加了土壤微生物多样性和丰富度,各物种在数量上的均匀程度变大。在土壤养分方面,T1、T2菌剂处理组铵态氮浓度显著高于对照组,硝态氮含量低于对照。在速效P方面,T1、T2含量比CK分别显著提高了8%、25%。在速效K方面,T1、T2含量显著高于CK,提高了15%和11%。枯草芽孢杆菌和褐球固氮菌菌剂改善了茶树根际土壤微生态环境,提高了土壤养分,表现出正面效应,是一种生态安全性较高的生物菌剂。 相似文献