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61.
Teresa Fuertes‐Mendizbal Igor Setin Jos M. Estavillo M. Begoa Gonzlez‐Moro 《植物养料与土壤学杂志》2010,173(6):907-919
An experiment was carried out to determine how the late application of nitrogen (N) fertilizer affects the use of pre‐anthesis carbon reserves during the grain‐filling period of pot‐grown wheat with no water shortage. Increasing doses (equivalent to 0, 140, and 180 kg N ha–1) of N fertilizer were applied, either in two amendments (stages GS20 and GS30) or in three amendments (stages GS20, GS30, and GS37, according to Zadoks scale). The management of fertilizer by combining an increased N rate with late N application was able to stimulate canopy development, to raise photosynthetic capacity and carbohydrate accumulation during the vegetative stages, and to increase grain yield. Based on the dynamics of carbohydrate accumulation in the ear, three phases were differentiated during the grain‐filling period, whose temporary pattern remained stable regardless of the fertilizer management. The net remobilization of carbohydrates started 12 d after anthesis from the leaves and 28 d after anthesis from roots and stems. The increase of the N dose with late N application allowed on one hand a lower use of the pre‐anthesis carbon reserves in favor of greater de novo photosynthesis during the grain‐filling period, and on the other hand greater relative contribution of the leaf and ear C reserves to remobilization towards the grain. Further splitting the dose increased only the relative contribution of ear C reserves. The stem contribution seemed to be independent of N applied whereas the root contribution tended to diminish with late N application. 相似文献
62.
棉株现蕾后即从营养生长进入生殖生长,但仍是营养生长占优势,以增大营养体为主。这一阶段的田间管理重点是在壮苗早发的基础上,采取合理的促控措施,调节棉株地上部和地下部、营养生长和生殖生长的关系,实现发棵稳长。发棵是高产的基础,稳长是高产的保证。 相似文献
63.
[目的]探究不同播种期对薏苡生长及产量的影响,选出适宜播种期。[方法]采用5个不同播种期、实行田间小区试验的方法。种植方式以窝行距60 cm×60 cm进行种植,每种种植期设3个小区,随机区组排列,小区面积80 m2。苗期以每穴4苗进行定苗。根据生长期进行两次追肥和除草,以及有关生长数据采集,测产验收。[结果]种植期对薏苡产量和生长都有很大的影响。播种期晚,将导致无效分蘖增多,侧枝减少,穗粒数降低,空瘪率高,千粒重减小,大籽粒所占百分率逐渐降低,最终产量降低,质量差。[结论]为了获得高产,播种期应选在清明节之前。 相似文献
64.
高寒草地西北针茅生长发育特征及与气象因子的关系 总被引:2,自引:0,他引:2
利用1999~2009年连续11年的定位观测数据,研究了高寒草地西北针茅的生长发育特征与气象因子的关系。结果表明,在3月中旬,如果气温升高,返青日会推迟,这主要因为高温促使土壤水分蒸发,而土壤干旱阻碍返青;返青后,如果≥0℃的积温不足或累计日照时数不足,针茅的抽穗期会推迟;开花期的当日平均气温在10~20℃,如果抽穗-... 相似文献
65.
[目的]研究围产期小尾寒羊血清T-SOD活性和MDA含量的变化。[方法]选择20只年龄在2~5岁之间的小尾寒羊,其中10只为待产母羊,10只为空怀母羊,分别于产前20d、产前10d、产前1d、产后1d、产后10d、产后20d颈静脉采血,测定血清T-SOD活性和MDA含量。[结果]围产期小尾寒羊在整个围产期内血清中T-SOD活性呈先下降后逐渐升高的动态变化,其中,在产前1d出现最低值且围产期小尾寒羊T-SOD活性均低于空怀小尾寒羊;围产期小尾寒羊在整个围产期内血清中MDA含量呈先上升后逐渐下降的动态变化,其中,在产后1d出现最低值且围产期小尾寒羊MDA含量均高于空怀小尾寒羊。[结论]怀孕和分娩对小尾寒羊T-SOD活性和MDA含量有一定的影响。 相似文献
66.
67.
半荒漠地区灌木饲料林营造技术研究 总被引:5,自引:0,他引:5
孙德祥 《干旱区资源与环境》1995,9(2):74-79
本文对半荒漠地区灌木饲料林的树种选择、经营管理等问题进行了初步探讨,给出了花棒、杨柴、柠条、沙柳、毛条、毛柳、白沙蒿、油蒿8个半荒漠地区灌木饲料林树种的造林适宜立地类型、最适造林季节、最佳造林密度、最适收获期以及最佳平茬年龄。 相似文献
68.
E. M. Van Hees-Boukema J. C. Zadoks 《European journal of plant pathology / European Foundation for Plant Pathology》1986,92(2):71-80
Urediospores ofPuccinia recondita f.sp.tritici were applied to wheat seedlings. Inoculated plants were placed in a growth chamber to expose the spores to dry periods from zero to nine days at near-optimal temperatures (ca 18 °C). The dry period was followed by a wet period varying from 2 to 24 hours for germination of spores and infection of plants. Infection results were subjected to analysis of variance. The main effects dry period, wet period, and temperature were highly significant. The dry period×wet period interaction was significant. The interaction implied that the effects of post-detachment, ripening of germinable spores appeared in their resulting infectivity. There were two forms of post-detachment ripening, a slow ripening during the dry period and a faster ripening during the wet period. The two forms of ripening showed a non-additive compensatory interaction. The effect of post-detachment ripening on infectivity of germinated spores was more pronounced at 15 than, at 18 or 20 °C; the effect was strongest during the first day of the dry period. At dry periods of over 6 days, infectivity of germinated spores decreased, especially at the higher temperatures. Prolonged exposure, of spores to a dry period apparently damages the spores even though they are still able to germinate.Samenvatting Uredosporen van de bruine roest van tarwe (Puccinia recondita f.sp.tritici) werden over het eerste blad van tarwekiemplanten verstoven. De aldus geïnoculeerde planten werden in een klimaatkamer geplaatst bij ca. 18 °C om de sporen bloot te stellen aan droge perioden van 0 tot 9 dagen. De droge perioden werden gevolgd door natte perioden van 2 tot 24 uur om de sporen te laten kiemen en de planten te infecteren. Na de natte periode werden de planten bij verschillende temperature geplaatst om de latente periode en de vorming van sporenhoopjes te bepalen. De hoofdeffecten op de vorming van sporenhoopjes waren zeer significant: duur van de droge periode, duur van de natte periode en temperatuur. Twee vormen van sporenrijping werden gevonden bij rijping vnn sporen, die los op het blad lagen (rijping, buiten de sporenhoopjes), een langzame rijping tijdens de droge periode en een snelle rijping tijdens de natte periode. Deze twee vormen van rijping vertoonden statistische interactie met enige wederzijdse compensatie. Het effect van deze sporenrijping (buiten de sporenhoopjes) op de infectiviteit van gekiemde sporen was bij 15 °C duidelijker dan bij 18 en 20 °C; het effect was het sterkst tijdens de eerste dag van de droge periode. Bij droge periodes langer dan 6 dagen daalde de infectiviteit, vooral bij de hogere temperaturen. 相似文献
69.
I. Vloutoglou B.D.L. Fitt J.A. Lucas 《European journal of plant pathology / European Foundation for Plant Pathology》1999,105(6):585-595
Controlled environment studies were conducted to determine the effects of inoculum density, temperature, leaf wetness and light regime on the infection of linseed by Alternaria linicola. The % cotyledons and leaves with symptoms, and the disease severity (% leaf area with symptoms) increased linearly when the inoculum density increased from 1×103 to 1×105 conidiaml–1. The first symptoms appeared on cotyledons and leaves 4 and 6 days after inoculation, respectively. Eight hours of leaf wetness were sufficient to initiate the disease at 25°C but not at 15°C, when 10-h periods of leaf wetness were required. % leaf area with symptoms was lower at 15°C than that at 25°C irrespective of the leaf wetness periods tested. Interruption of a continuous leaf wetness period by a 12-h dry period, occurring at any time between 1 and 18h after inoculation, decreased the % cotyledons with symptoms and the disease severity, with the greatest reductions (60% and 100%, respectively) being observed when the dry period began 6h after inoculation. A. linicola conidia were able to exploit successive 12-h periods of leaf wetness cumulatively to infect linseed plants. Disease incidence and severity were positively correlated with the dark period following inoculation, but they were negatively related to the length of the initial light period. Our findings suggest that infection of linseed by A. linicola and further development of symptoms can occur under unfavourable environmental conditions. 相似文献
70.
lntroductionTherearemanystudiesonOrientaIWhiteStorks.Thestudysubjectsincludepopulation,distribution,migration,ecology,historicstatusandconservation,captivepropagation,reproductivebioIogyandbe-haviors,etc.KyDkoArchibaIdandBernardSchmitt(1991)reportedthecomparisonbetWeentheorientaIWhiteStorkandtheEuropeanWhiteStork.TheyalsodescribedspeciaIbehaviorsofiIlCIattering"anddi-videdinto3styIes.ThesearethreatbiIIcIattering",courtshipbilIclattering"andcontactbilIclattering".TheyexpIainedthefem… 相似文献