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21.
根据海南岛的气候特点,采取了特定的技术措施,育苗用水加FeCl3处理、二次过滤;亲蚶排放时,单独设置作精池;附着基质选择非酸性海泥;培养耐高温的饵料。另外,还做了亲蚶和稚贝倒池培养实验,结果证明:12小时倒池一次,亲贝培养效果最好;2天倒池一次,稚贝培养效果最好。  相似文献   
22.
“长荡湖1号”A系和B系是分别以成活率和大规格为主要选育指标建立的两个相互独立的中华绒螯蟹(Eriocheirsinensis)选育品系,为评估“长荡湖1号”偶数年群体(偶数年繁殖孵化)选育第二代(G2)的选育效果,本实验以未选育群体作为对照组,比较了两选育品系和对照组在实际池塘养殖条件下的生长、性腺发育和养殖性能。结果显示:(1)两选育品系A系和B系在扣蟹、成蟹养殖阶段的最终平均体质量均高于对照组,其中B系雌体与对照组具有显著差异(P<0.05);无论雌体还是雄体, B系最终平均体质量均略高于A系,但无显著差异(P>0.05);(2)各组实验蟹雌雄个体在成蟹阶段的生殖蜕壳高峰期分别为2021年8月10~30日和8月30日~9月20日,各组成蟹完成生殖蜕壳后性腺迅速发育,并且性腺发育后期,对照组GSI最高、B系的GSI最低;(3)就成活率而言,三组蟹在扣蟹和成蟹阶段的成活率大小顺序为:A系>对照组>B系,差异不显著(P>0.05);而在产量、大规格蟹比例和饲料系数方面,两选育品系均优于对照组。综上,经过两代配套系选育,“长荡湖1号”A系和B系均获得良好的选...  相似文献   
23.
遥感在森林精准培育中的应用现状与展望   总被引:1,自引:0,他引:1  
周凯  曹林 《遥感学报》2021,25(1):423-438
随着社会经济快速发展及人口增长,中国木材供需矛盾突出,对外依存度高。面对有限的土地资源,迫切需要更为高效、高质量地培育森林资源,在定向培育和集约经营等的各个环节实现培育技术精准化。现代遥感技术所构建的多平台、多角度、多模式立体观测体系及定量分析方法是森林精准培育的关键技术。以遥感技术为核心所构建的从土壤类型分析、土地适应性评价、生态环境模拟到林木育种、灌溉施肥、林木长势监测、病虫害防治等一体化、精准化的森林精准培育新体系,将全面支撑现代林业的整体提质增效和森林质量精准提升。本文首先介绍了RGB相机、多光谱、高光谱、激光雷达、热红外和荧光传感器在森林精准培育中应用现状,并对其应用特点及测量指标进行了综合比较;然后,重点介绍了遥感在林木良种选育、营养胁迫监测诊断及水肥精准喷灌以及森林病虫害防治与健康评估这3个森林精准培育重要方向上的应用,并分析了各应用方向的共性需求;最后,从3个方面,即多源遥感信息融合,人工智能、物联网及3S技术集成,以及遥感数据与生理生态模型和辐射传输模型等的集成应用,分析了未来遥感技术在森林精准培育中的发展趋势及应用前景。  相似文献   
24.
Bayesian and restricted maximum likelihood(REML) approaches were used to estimate the genetic parameters in a cultured turbot Scophthalmus maximus stock. The data set consisted of harvest body weight from 2 462progenies(17 months old) from 28 families that were produced through artificial insemination using 39 parent fish. An animal model was applied to partition each weight value into a fixed effect, an additive genetic effect, and a residual effect. The average body weight of each family, which was measured at 110 days post-hatching, was considered as a covariate. For Bayesian analysis, heritability and breeding values were estimated using both the posterior mean and mode from the joint posterior conditional distribution. The results revealed that for additive genetic variance, the posterior mean estimate( δ_a~2=9 320) was highest but with the smallest residual variance,REML estimates( δ_a~2=8 088) came second and the posterior mode estimate( δ_a~2=7 849) was lowest. The corresponding three heritability estimates followed the same trend as additive genetic variance and they were all high. The Pearson correlations between each pair of the three estimates of breeding values were all high,particularly that between the posterior mean and REML estimates(0.996 9). These results reveal that the differences between Bayesian and REML methods in terms of estimation of heritability and breeding values were small. This study provides another feasible method of genetic parameter estimation in selective breeding programs of turbot.  相似文献   
25.
白腹鹞(Circus spilonotus)又叫东方泽鵟,在阿勒泰地区布尔津县(47°46'N, 86°49'E)有多次记录,现确定为新疆新纪录种(或亚种)。但是,在2015年5~7月繁殖期观察,发现它可能与雌性白头鹞(Circus aeruginosus)杂交。两者无论是在形态与行为,还是在地理分布隔离方面,都存在疑团,其分类地位值得商榷。  相似文献   
26.
姚文捷 《地理科学》2015,35(9):1140-1147
通过引入区位熵的方法,构建生猪养殖产业集聚演化的环境效应模型,旨在从理论层面揭示出生猪养殖污染本身的特殊性和内在的规律性。以嘉兴市辖区为样本的研究表明,生猪养殖污染集聚程度与生猪养殖产业集聚程度存在的倒U型曲线关系,本质上是生产的环境负外部性效应,以及对其实施纠正措施的演化轨迹。生猪养殖生产的环境负外部性效应曲线在污染治理政策的作用下,随着产业集聚程度的提高由向右上方倾斜而逐渐向下弯曲;在受到耕地资源约束时,会向上平移;在因下弯而减轻的污染集聚程度被因上移而增加的污染集聚程度所抵消并盖过时,污染治理政策则有可能是失效的。因此,生猪养殖污染治理政策的实施,必须将城镇化推进所引起的耕地资源的变化考虑在内。  相似文献   
27.
Two experiments were performed to assess the effect of photoperiod and temperature on spawning of Panulirus ornatus. In experiment 1, sexually mature lobsters taken from the wild during summer were held at one of two photoperiods, winter (13 Light: 11 Dark) and summer (14.5 Light:9.5 Dark). Additionally, lobsters were also exposed to either summer (29°C) or winter (24°C) average water temperatures. Spawning was significantly greater when animals were exposed to summer photoperiod than to winter photoperiod, irrespective of temperature. Although a higher percentage of lobsters spawned when placed under a higher temperature, this trend was not statistically significant. In experiment 2, sexually mature lobsters were taken from the wild during winter and exposed to the same two photoperiods as in experiment 1, at a summer equivalent temperature of 29°C. Breeding started earlier and was more successful at the summer photoperiod. Time to first breeding was 17 weeks after exposure to summer photoperiod, compared with less than 1 week in experiment 1, and did not occur until individuals had moulted. Moulting occurred in 81% of lobsters, primarily after an increase in temperature to 29°C. The time between moulting and mating was varied and there was no significant difference in moult frequency between the two experimental photoperiods. After the lobsters had moulted, breeding success was reached earlier if photoperiod was lengthened. Results suggest photoperiod is the primary cue for the onset of gonad maturity and mating activity, with temperature playing a less important role. Physiological rest and possibly a moult may be required between breeding seasons before spawning can occur. Furthermore, temperature may be an important cue for pre‐reproduction moulting.  相似文献   
28.
Daily phytoplankton production was estimated at the sea surface in the southern Benguela Current during January, March, April and October 1978 by different methods of calculation. Actual daily production (P24 meas) was obtained from a series of short-term (3—4 h) incubations spanning 24 hours. Daily production was also extrapolated from single measurements during daylight by the "time factor" and "light factor" methods of calculation. These estimates (P24 calc) vary considerably from P24 meas, but on average they underestimate daily production. Estimates by the "light factor" method are generally lower and more variable than those from the "time factor" method. Differences in amplitude and timing of fluctuations in the rate of net production during daylight make it impossible to calculate reliable factors for correcting diel variations in photosynthesis when estimating daily production from short-term measurements. It is suggested that the effects of diel variation in production are likely to be less significant in the euphotic zone as a whole than at the sea surface alone.  相似文献   
29.
用紫色蚌和非紫色蚌制取细胞小片,分别插入紫色蚌和非紫色蚌外套膜内,探究三角帆蚌(Hyriopsis cumingii)无核珍珠颜色与制片蚌、育珠蚌的关系;用不同类型制片蚌的不同部位制取细胞小片,分别插入育珠蚌外套膜内,进一步探究珍珠颜色与制片蚌珍珠质颜色的关系。结果表明,以紫色蚌为制片蚌,所产的珍珠为紫色系,珍珠紫色深浅与细胞小片所对应部位的制片蚌珍珠质紫色深浅呈正相关。以非紫色蚌为制片蚌,所产的珍珠有白色系和黄色系,珍珠黄色深浅与细胞小片所对应部位的制片蚌珍珠质黄色深浅呈正相关。三角帆蚌外套膜无核珍珠颜色是由提供细胞小片的制片蚌珍珠质颜色所决定,而与育珠蚌无关。该结论支持珍珠囊表皮细胞来自于移植细胞小片的观点。该结果表明,通过定向选育纯紫、纯白色贝壳珍珠质三角帆蚌新品系,即可培育出纯紫、纯白色无核珍珠。  相似文献   
30.
大泷六线鱼人工繁殖及育苗技术初步研究   总被引:2,自引:0,他引:2  
总结了2009 ~2010年关于大泷六线鱼(Hexagrammos otakii)人工繁殖及育苗技术的研究结果,论述了大泷六线鱼苗种繁育的关键技术.通过对亲鱼强化培育和促熟,创新发明人工平面授精技术和网箱吊式孵化技术,加强饵料的合理搭配与投喂、水质调控技术等措施,突破了大泷六线鱼人工繁殖的技术难点,明显提高了受精率、孵化率和苗种成活率,解决了人工繁殖大泷六线鱼苗种生产问题.在水温16~ 17℃,盐度31,光照500 ~ 1000 1x的培育条件下,大泷六线鱼鱼苗经过90 ~ 100 d的培育,全长生长至5 ~6cm.2009和2010年分别培育出全长5 cm以上大泷六线鱼鱼苗4.1万尾、11.4万尾,苗种成活率分别达到41.7%、43.2%,在国内首次实现了大泷六线鱼人工规模化繁育.  相似文献   
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