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71.
红杂18是以红213为母本,黄苗试材9375为父本,配制成适宜罐藏加工和长途运销的番茄一代杂种。具有高抗TMV、中抗CMV、果实硬度高、抗裂、耐压、耐贮运、果实加工性状优良等特点。已在新疆、甘肃、宁夏、广西、云南等省区的加工番茄生产基地和远运外销生产基地推广649.8hm2。 相似文献
72.
During 11 breeding seasons, 351 7- to 10-day-old horse embryos were nonsurgically transferred into recipients that ovulated between 3 and 10 days earlier. Pregnancy rates at 14 and 40 days and foaling rates were 77.8% (273/351), 69.2% (243/351), and 64.4% (226/351), respectively. Pregnancy loss between 14 and 40 days was 11% and between 40 days and delivery was 7%. The transfer of quality grade 3 to 4 embryos resulted in a significantly lower pregnancy rate at 14 days compared with the transfer of grade 1 to 2 embryos (46.2% vs. 79%; P < .05). Eight-day-old embryos resulted in significantly lower pregnancy losses than day 9 or 10 embryos, as occurred for embryos between 400 and 1200 μm compared with embryos <400 μm. Embryos recovered from mares >20 years resulted in a significantly higher pregnancy loss rate than those recovered from younger mares. The same happened for embryos coming from mares affected by reproductive pathologies compared with healthy mares performing sport activity. None of the evaluated parameters influenced recipients' foaling rate significantly. 相似文献
73.
Summary Using visual selection for off-types and image analysis to select against maturation mutants, a line combining improved late
blight resistance and yield was isolated in an in vitro mutagenesis programme from a population of 2101 putative mutants.
The adventitious regenerants from mutagenesis treatment, including spontaneous mutants (somaclonal variants), were subjected
to serial subculture of the apical bud in vitro and two cycles of apical cuttings in vivo to breakdown chimeras. The selected
line was stable in trials over five years; others were unstable or failed to combine improvement in late blight resistance
with high yield. Leaf and tuber image analysis was used to characterize selected lines. Lines that differed most from cv.
Golden Wonder in yield and late blight resistance were more easily distinguished from the control by image analysis. The role
of image analysis in negative selection and in determination of the relatedness of mutants to the control is discussed. 相似文献
74.
M. S. Radwan M. M. F. Abdalla G. Fischbeck A. A. Metwally D. S. Darwish 《Plant Breeding》1988,100(4):289-298
Six populations of faba bean (Vicia faba L.) were developed through various selection schemes to examine the influence of selection In improving tolerance to Orobanche crenata (Forsk.) in local faba bean stocks. All populations trace their origin to 209 farmers’ seed lots that were collected from Egypt. The entries of each population were grown during the 1982/1983 season in the Orobanche nursery located at Giza in Egypt. Comparison among means of the selected, populations showed that more progress in improving Orobanche tolerance could be achieved from combined selection between and within lots. Between-lots selection was less efficient than single-plant selection. Results, of this study show that considerable progress could be achieved from selection for Orobanche tolerance in local faba bean germplasm. There was sufficient residual genetic variation in the selected populations to expect substantial progress from further selection for most tolerance traits. 相似文献
75.
76.
海氏桨角蚜小蜂Eretmocerus hayati是烟粉虱Bemisia tabaci的优势寄生蜂,了解寄生蜂的交配行为有利于完善其规模化繁殖技术。通过对海氏桨角蚜小蜂的首次交配及再次交配、配偶选择等行为学观察,以及多次交配对雌蜂繁殖量影响的生物学试验,明确了该蜂的交配过程包括求偶、交尾前期、交尾和交尾后期;雌蜂在整个生活史中未观察到再次交配;雄蜂可在首次交配后迅速进行再次交配,首次交配后1 h内的再次交配率为83.3%,62.5%的个体可在2 h内完成第3次交配,再次交配的行为持续时间显著低于首次交配;雄蜂的交配次数对自身寿命及其配偶的寄生量无显著影响;此外,在配偶选择中,处女蜂倾向于接受有交配经历的雄蜂,多头雄蜂间存在竞争行为进而干扰交配成功率。 相似文献
77.
Experiments were conducted with early segregating generations of a selected narrow-leaf lupin cross to determine the effectiveness of selection for yield based on alternative criteria. F2 plants were selected on the basis of seed yield and several other yield-related characters to generate separate F3 populations. Randomly selected plants from each population were grown over the summer (off-season) in a glasshouse to generate F4 populations. Analyses of relationships between F2 plant measurements and F3 progeny mean yields revealed significant correlations only for those characters with the highest heritabilities - flowering time, 100 seed weight and harvest index. However, selection for the earliest flowering F2 plants followed by selection within this group of plants with the highest number of pod bearing branches would result in the greatest increase in F3 mean yield. The F2-derived F4 populations with the highest seed yields were those obtained by selection for total plant dry weight, number of pod bearing branches and number of pods per plant. Improvement in commercial crop yield should therefore be obtained through selection in early generations for those characters contributing to the greatest number of pods per unit area. A scheme involving selection for early flowering and high number of pod bearing branches in the F2 combined with replicated yield tests in the F4 is proposed. 相似文献
78.
利用12个微卫星标记对鲤(Cyprinus carpio)的4个野生群体 [清水江鲤、太湖鲤、黄河鲤(C.carpio haematopterus)和黑龙江鲤(C.carpio amurensis)] 和2个选育群体 [福瑞鲤(C.carpio var. FFRC)和松浦镜鲤(C. carpio var. specularis 'Song-pu')] 共208尾个体进行遗传分析。结果显示,12个位点共检测到341个等位基因,平均等位基因数为28.67,其中1个位点(HLJ1127)检测到正向选择压力;选育群体的遗传多样性参数普遍低于野生群体,其中松浦镜鲤群体的各项参数均值最低(Na=6.82,Ho=0.54,PIC=0.50),清水江鲤群体的各项参数均值最高(Na=21.25,Ho=0.80,PIC=0.91);分子方差分析显示,整体遗传变异主要来自群体内,但群体间呈极显著遗传分化(P<0.01);基于群体Nei's遗传距离的UPGMA聚类树和PCoA分析表明,鲤4个野生群体间遗传距离较近,而与2个人工选育群体间遗传距离较远;基于个体遗传结构及PCoA分析显示部分野生个体遗传结构比较混杂,而选育个体的遗传结构则相对单一。研究表明,中国鲤野生资源具有较高的遗传多态性,而人工选育群体维持着较纯的遗传种质。 相似文献
79.
清洁发展机制(CDM)对中国农村沼气工程经济性影响 总被引:2,自引:0,他引:2
按中国农村户用沼气池的不同适用对象分类对其运行成本分别进行了研究,并分析了其不同的温室气体减排效果以及在清洁发展机制(CDM)下出售这些减排权(CERs)可以带来的额外经济效益,对改善沼气工程直接经济效益的措施进行了讨论。结果表明:沼气工程直接经济效益不高,在清洁发展机制(CDM)下通过出售减排权(CERs),经济性可得到改善。沼气项目对于燃煤的农户将具有市场竞争力和投资吸引力。 相似文献
80.