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81.
82.
旨在研究果园土壤有机质与土壤氮素养分的相关性与空间分布变化,为果园土壤的可持续利用提供依据。对庆阳苹果主产区30个果园土壤有机质含量和土壤氮素养分进行农化分析。结果表明:0~20 cm果园土壤有机质与全氮含量的相关关系为y=0.055x+0.140,相关系数R2=0.940,土壤有机质与碱解氮含量的相关关系为y=3.061x+26.65,相关系数R2=0.414,土壤全氮与碱解氮含量的相关关系为y=55.28x+18.83,相关系数R2=0.441;20~40 cm果园土壤的有机质与全氮含量的相关关系为y=0.045x+0.250,相关系数R2=0.721,土壤的有机质与土壤碱解氮含量的相关关系为y=2.237x+23.84,相关系数R2=0.158,土壤的全氮与碱解氮含量的相关关系为y=57.47x+5.141,相关系数R2=0.298。 相似文献
83.
Influences of processing parameters on tensile property, stability and bulk of core-and-effect air textured yarns of diacetate
and polyester filaments are mainly examined in this paper. When the air pressure is raised, the tenacity and breaking elongation
of textured yarns are reduced, Instability I and II tend to decrease at first and then increase, the core bulk declines markedly
at first and then changes slowly, whereas the overall bulk changes little at first and then goes up greatly. With increase
in texturing speed, the yarn tenacity and breaking elongation both drop initially then begin to increase, the core bulk and
overall bulk are almost linearly increased, while the yarn instability changes with an unclear trend. When the winding underfeed
ratio is increased, the yarn tenacity, breaking elongation and core bulk are reduced, but the yarn stability is slightly improved.
The wetting of the core component produces higher tenacity, breaking elongation, instability and bulk, compared with that
of the effect component or that of both, but the difference is insignificant. 相似文献
84.
Spandex has been successfully applied on modified worsted spinning system to produce spandex core spun yarn. However it’s
difficult to produce wool/spandex core-spun yarn on woolen spinning system with the same modified device because the drafting
device of the two systems is quite different. A new method is introduced to apply spandex on woolen spinning system in this
paper. Core-spun yarn produced in this way has good appearance and quality by comparing with normal yarn. A series of experiments
were carried out to study the influence of spandex drafting ratio and yarn twist factor on tensile properties and elasticity
of core-spun yarns. The results indicate that core-spun yarn with spandex drawing ratio of 2.5 and twist factor of 13.63 has
highest value of tenacity and breaking elongation. 相似文献
85.
86.
In present work, PET FDY has been used to blend with diacetate filaments by air texturing process and core-and-effect air-textured
yarns have been produced. The influences of both over-feeds of core and effect components on properties of textured yarns
were mainly examined. It was observed that a spun-like effect of diacetate filaments occurred during air texturing and there
were a little amount of free fiber ends besides loops on blended air textured yarns, while the number of free fiber ends changed
little with variation in over-feeds. The tenacity of textured yarns decreased with increase in over-feeds of effect or core
component. The breaking elongation increased with increase in over-feed of effect component, but decreased with increase in
over-feed of core component. The yarn stability improves when both over-feeds are increased. The effect of over-feeds on boiling
water shrinkage shows no clear trend. The core and average diameters are higher at high over-feed of effect component, but
the over-feed of core component exhibits little effect on yarn diameters. The number and size of loops are increase with increased
over-feed of effect component. 相似文献
87.
为保障枸杞产品质量安全,采果期不受化学农药干预,本研究通过室内毒力测定和田间药效试验评价了蒙古蒿挥发油的杀虫活性。结果表明,蒙古蒿挥发油对棉蚜的LC50为7.82mg/mL;对枸杞木虱的LD50为2.89μg/头;对西花蓟马的LC50为2.80mg/mL,均低于对照药剂印楝素提取物,其中胡椒酮、PPG2-甲醚和桉油烯醇起主要杀虫作用。利用响应面分析,蒙古蒿挥发油制备成8.5%蒙古蒿挥发油微胶囊剂,该制剂在质量浓度6kg/hm2条件下,药后1d,对枸杞蚜虫、西花蓟马和枸杞木虱的防效分别为75.95%、58.81%和32.14%,高于对照0.3%印楝素乳油,杀虫效果一直持续到21d。本研究将蒙古蒿挥发油微胶囊应用于枸杞园采果期防治主要害虫,持效期长,具有进一步开发成高效植物源农药的潜力。 相似文献
88.
小麦赤霉病是世界性病害,严重危害小麦生产,已成为我国粮食安全的重大威胁.国内外在小麦赤霉病抗源筛选、抗病基因发掘与克隆及抗赤霉病育种等方面取得重大进展.从抗赤霉病早期遗传研究、抗病基因/QTL挖掘、基因/QTL效应研究和抗病基因克隆等方面回顾了抗赤霉病遗传研究进展,并对基于表型选择和分子标记辅助的抗赤霉病育种成就进行了总结.在分析现有普通小麦抗源和外源抗性材料的育种利用局限的基础上,针对性地提出3点建议:一是加强对已育成和推广品种的抗性鉴定,筛选其中的抗病品种进行抗病基因研究;二是利用抗病基因的加性效应聚合现有品种携带的不同抗病基因,减少抗病基因与不利农艺性状的连锁累赘,培育抗赤霉病高产品种;三是加大外源基因的发掘、改造和利用. 相似文献
89.
90.