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91.
A bioenergetics model of the entire life cycle of the three‐spined stickleback,gasterosteus aculeatus 下载免费PDF全文
Charlène Leloutre Alexandre R. R. Péry Jean‐Marc Porcher Rémy Beaudouin 《Ecology of Freshwater Fish》2018,27(1):116-127
A whole life‐cycle bioenergetic model based on the dynamic energy budget (DEB) theory was proposed for the three‐spined stickleback (Gasterosteus aculeatus). To develop this model, experiments on growth and reproduction were performed: adult and juvenile growth, size at first reproduction and amount of eggs spawned by females were monitored under different feeding levels and temperatures. The DEB parameters were estimated, using Bayesian statistics, based on the data produced during these experiments and on other data found in the literature. The model fitted accurately the different data used for the calibration process and, in addition, predicted accurately the data sets used to assess its predictability. Our bioenergetic model of the whole life cycle of the three‐spined stickleback accounting for environmental variations could contribute in many ways to improved ecological assessment: supporting change of scale from individual to populations; developing new biomarkers of exposure and effect; analysing ecotoxicity tests with biology‐based models. 相似文献
92.
黑龙江省水稻种质资源农艺性状与产量关系的分析 总被引:2,自引:0,他引:2
为明确黑龙江省主要水稻种质资源农艺性状与产量之间的关系,更高效的选育水稻新品种,以139份水稻种质资源为材料,采用描述性分析、相关分析、通径分析等方法对影响产量的主要农艺性状进行了试验研究。结果表明,黑龙江省水稻种质资源比较丰富,12个农艺性状的变异系数均≥11%,并且稳定性很好;分蘖株数、每穗粒数、有效穗数、剑叶宽度与产量呈正相关关系,谷粒形状与产量呈负相关关系;10个农艺性状可以归为4个主成分,其累计贡献率为68.759%。 相似文献
93.
为了探索莱芜市土地利用变化规律,论文分别基于Markov模型与GM(1,1)模型对莱芜市进行了2015-2050年土地利用变化预测,分析讨论了预测结果。结果表明:(1)2种预测模型得出各地类变化趋势一致,短期内相应年份预测值吻合度高,说明短期内预测结果可信,中长期预测的趋势可作参考。(2)耕地在2015-2020年之间基本保持不变,2020-2050年呈小幅度减少趋势;而园地、林地、草地自始至终都为减少趋势,其中草地的减少幅度最大;城镇村及工矿用地、交通运输用地为增加趋势,其中城镇村及工矿用地增幅最大;水域及水利设施用地、其他土地略有减少,幅度很小。2种模型预测的短期内预测结果是可信的,可为莱芜市土地利用规划提供科学依据,预测方法可为土地利用变化预测提供参考。 相似文献
94.
Golam Ahmed David Takuwa Inonge T. Chibua Zibisani Bagai Lebogang Morekisi Hilary Shoniwa 《Communications in Soil Science and Plant Analysis》2016,47(4):512-520
An ultrasonic method using two approaches, A and B, along with a reference Environmental Protection Agency (EPA) Method 3050B [i.e., a mixture of 30 mL of nitric acid–hydrochloric acid–hydrogen peroxide–water (HNO3-HCl-H2O2-H2O)] were contrasted for leaching of a plant matrix. The trace metals were arsenic, cadmium, cobalt, chromium, copper, mercury, manganese, nickel, lead, selenium, and zinc (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se and Zn) and quantified by ICP-OES followed by an investigation into residue formation and the impact of digestion time. Approach B was the most accurate and precise with percent recoveries ranging between 99 and 120%, whereas ultrasonic approach A and the USEPA method 3050B gave similar results with poor accuracies and precisions. In the optimization of the digestion time using approach B, the total metal recovery was fairly the same over a period of 120 min except for Cr and Cu, which showed slight variations. 相似文献
95.
近50年菏泽市暴雨气候特征 总被引:2,自引:1,他引:1
为了揭示菏泽市暴雨气候特征,笔者利用菏泽市9个气象站50年的暴雨资料进行了研究。选取1960—2009年历年3—11月菏泽市9个站的逐日(20:00—20:00)降水资料,采用多种统计方法分析菏泽市多年暴雨气候规律。结果表明:菏泽市暴雨年际变化及年代际变化离差较大,60年代暴雨较多,之后较少,2000年之后又呈增长趋势。并且在1974年和2003年发生明显突变。1974年以前和2003年以来暴雨发生次数较多,1975—2002年期间暴雨发生次数较少。暴雨发生有明显的区域性,区域分布呈东南向西北递减的趋势,并且南北易受不同系统影响。本研究对做好暴雨预报,开拓气象服务,防灾减灾有一定参考作用。 相似文献
96.
为了更好揭示湖北省双季稻生育期特征, 定量评估气象因子对双季稻产量影响, 选取双季稻产区 4个代表站气象因子和产量资料, 运用动态统计气候影响评估模式分析气象因素变化对产量影响效应。结果表明: 早稻播种 4月 2日, 成熟 7月 18日, 生育期 108天; 晚稻播种 6月 20日, 成熟 10月 22日, 生育期 125天。早、 晚稻的生育期长度变化有所差别, 江夏、 监利早稻生育期长度呈延长趋势, 阳新、 孝感则呈缩短趋势; 江夏、 阳新和孝感晚稻生育期长度呈缩短趋势, 监利则相反。动态统计气候评估模式评估发现受地理、 水文条件影响, 气温对双季稻生育期影响最大, 气温、 日照在双季稻关键生育期变化对产量形成有利, 而降水则相反, 气温升高和降水量减少有利产量形成。 相似文献
97.
应用分层抽样技术估计北部湾底拖网渔业产量 总被引:1,自引:0,他引:1
传统的按行政单元逐级上报的渔业产量调查方法在数据获取过程中受人为因素的干扰,而全面普查的方法受限于时间和经费,相比而言,抽样调查是一种科学合理的方法。本研究于2007年8月对北部湾底拖网产量进行了调查,以全体底拖网渔船为抽样总体,按功率段划分了抽样层次,按比例分配了抽样单元数,分别以生产渔船总数和总功率数推算总产量,并比较了这两种方法的方差。结果表明,用每kW平均产量估计总产量的变异系数为1.13%,用单船平均产量估计总产量的变异系数为14.65%。同时由于渔业抽样调查的难点在于总体船数的掌握,建议统计推断时,采用单位渔捞努力量渔获量(CPUE)推算总体渔获量。 相似文献
98.
早实核桃不同品种抗旱性综合评价 总被引:3,自引:0,他引:3
以12 个早实核桃品种苗木为试材,采用自然干旱胁迫及复水的方法,测定了复水后各品种与抗旱性有关的生长指标、生理生化指标、光合指标及叶绿素荧光指标。对复水后各指标进行主成分分析,筛选出影响抗旱性的5 个主要指标,利用隶属函数对早实核桃品种的抗旱性进行了综合评价。结果表明:12 个早实核桃品种抗旱性强弱依次为:辽核1 号 > 中林5 号 > 新早丰 > 温185 > 鲁光 > 中林1 号 > 辽核4 号 > 扎343 > 强特勒 > 香玲 > 西林2 号 > 西扶1 号。此评价结果与大田试验结果基本一致。 相似文献
99.
J.-P. Rossi J.-C. Samalens D. Guyon I. van Halder H. Jactel P. Menassieu D. Piou 《Forest Ecology and Management》2009
Bark beetles are notorious pests of natural and planted forests causing extensive damage. These insects depend on dead or weakened trees but can switch to healthy trees during an outbreak as mass-attacks allow the beetle to overwhelm tree defences. Climatic events like windstorms are known to favour bark beetle outbreaks because they create a large number of breeding sites, i.e., weakened trees and for this reason, windthrown timber is generally preventively harvested and removed. In December 1999, the southwest of France was struck by a devastating windstorm that felled more that 27 million m3of timber. This event offered the opportunity to study large-scale spatial pattern of trees attacked by the bark beetle Ips sexdentatus and its relationship with the spatial location of pine logs that were temporally stored in piles along stand edges during the post-storm process of fallen tree removal. The study was undertaken in a pure maritime pine forest of 1300 ha in 2001 and 2002. We developed a landscape approach based on a GIS and a complete inventory of attacked trees. During this study more than 70% of the investigated stands had at least one tree attacked by I. sexdentatus . Spatial aggregation prevailed in stands with n≥15 attacked trees. Patches of attacked trees were identified using a kernel estimation procedure coupled with randomization tests. Attacked trees formed patches of 500–700 m2 on average which displayed a clumped spatial distribution. Log piles stemming from the sanitation removals were mainly distributed along the large access roads and showed an aggregated spatial pattern as well. The spatial relationship between patches of attacked trees and log pile storage areas was analyzed by means of the Ripley’s statistic that revealed a strong association at the scale of the studied forest. Our results indicated that bark beetle attacks were facilitated in the vicinity of areas where pine logs were stored. The spatial extent of this relationship was >1000 m. Similar results were obtained in 2001 and 2002 despite differences in the number and spatial distribution of attacked trees. The presence of a strong “facilitation effect” suggests that log piles should be removed quickly in order to prevent outbreaks of bark beetles. 相似文献
100.