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Resistance to DMI fungicides is a problem in both agriculture and medicine. Several mechanisms of resistance exist, but, as yet, few have been characterised in field resistant strains of plant pathogens. One approach to evaluating the role of mutations in the sterol 14α demethylase (14DM) target site requires cloning this gene and confirming its identity by complementation in an appropriate mutant. The azole‐resistant mutant, Erg 40, of Ustilago maydis which is totally blocked at the 14α demethylation step in sterol biosynthesis seems to be suitable for such expression studies. Transformation of Erg 40 with a plasmid containing the yeast 14α demethylase (CYP51A1) gene removed the block in sterol biosynthesis and generated azole‐sensitive transformants. Detailed analysis of these transformants failed to detect the presence of the yeast gene and suggested, instead, that changes in sterol biosynthesis resulted simply from the transformation protocol and not from the incorporation of extracellular DNA. Subsequent sequence analysis has revealed a mutation in the 14α demethylase gene of Erg 40. The results suggest that azole resistance in Erg 40 is not simply controlled by this mutation but involves some additional regulatory function, and consequently Erg 40 is not suitable for complementation studies with CYP51A1 genes. © 2000 Society of Chemical Industry 相似文献
43.
Maize production in temperate countries is threatened by late wilt, caused by Magnaporthiopsis maydis. Plant infection occurs early after sowing, but symptoms appear from flowering onwards. The disease is mainly controlled by genetic resistance, which is often partially expressed in the field. Development of disease symptoms is also highly dependent on environmental conditions. This study looked at whether production and growth of susceptible maize are affected by M. maydis under environmental conditions that are suboptimal for disease development. In addition, the effect of water availability on disease development under optimal conditions was determined. Pot experiments were conducted in an open-air enclosure in 2013, 2015 and 2016. Under unfavourable conditions for disease (low air temperature and relatively high air humidity), aboveground symptoms did not appear in the plants despite growth and production variables being clearly altered by the fungus. When air temperatures and humidity were optimal for disease development (air temperatures relatively high and humidity rather low), leaf symptoms on inoculated plants became apparent but with secondary importance compared to decreases in growth and production. The pathogen also affected the root:aboveground biomass ratio to a greater extent when the plants were under good water conditions than under deficit irrigation. Under optimal conditions and with good soil water content, the infected crop may end its cycle without symptoms, with the disease undetected, although reductions in yield and aboveground biomass can occur. 相似文献
44.
玉米作为重要的粮、饲、工兼用作物, 是重要的战略资源, 在国民经济中具有举足轻重的作用。但在实际生产过程中, 玉米受多种病虫害的威胁, 其中由玉蜀黍平脐蠕孢Bipolaris maydis引起的玉米小斑病严重影响玉米产量与品质, 是制约玉米高产与稳产的重要因素之一。近些年该病害的发病频率与严重程度均呈快速增长的态势, 对我国玉米安全生产构成巨大的潜在威胁。本文综述了玉米小斑病发生概况, 包括发生时期和引起的主要症状; 概括了玉米小斑病菌的侵染过程和相关功能基因的致病机制; 总结了抗玉米抗小斑病基因的定位、克隆与功能分析方面的研究进展, 玉米小斑病的防治措施等, 并对未来研究提出了一些建议和展望, 以期为玉米小斑病可持续治理提供理论参考和研究思路。 相似文献
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46.
低浓度玉米小斑病菌C小种毒素培养滤液诱导寄主抗性的研究 总被引:1,自引:0,他引:1
利用低浓度玉米小斑病菌C小种毒素培养滤液作为激发子诱导玉米获得抗病性。以一对同核异质玉米B37自交系为试材,采用离体叶片接种法检测适宜诱导抗性的低浓度玉米小斑病菌C小种毒素培养滤液作为激发子诱导玉米抗病性的适宜诱导浓度,测定与抗病性相关酶的变化。经用1∶50和1∶60的低浓度玉米小斑病菌C小种毒素培养滤液预处理植株,再接种高浓度(1∶10)毒素培养滤液处理的病斑面积分别为(0.30±0.14)和(0.36±0.17)mm2,而对照为(2.70±0.24)mm2,是处理的7.5~9倍,差异极显著。经0~72 h的动态检测,以1∶60预处理效果为最佳,与对照相比,苯丙氨酸解氨酶(PAL)活性平均提高了23.4%,过氧化物酶(POD)活性平均提高了65.9%,有害物质丙二醛(MDA)的含量平均降低了28.2%。叶片内部所产生的生化反应与叶片表面的抗性病理反应相吻合,证实低浓度玉米小斑病菌C小种毒素滤液本身能够成功地作为激发子来诱导寄主-玉米获得抗性。 相似文献
47.
The influence of invasive plant species on native community composition is well-documented, but less is known about underlying mechanisms. Especially scarce is knowledge about effects on biotic interactions such as relationships between native plants and their pollinators. In this study we investigate if pollen transfer from the invasive and highly pollen productive Carpobrotus spp. affects seed production and/or seed quality in three native species. We monitored pollinator movements and pollen loads on pollinators and native stigmas, and in a field pollination experiment we investigated the effect of invasive pollen on reproduction. Invasive pollen adhered to pollinators, pollinators switched from Carpobrotus spp. to natives, invasive pollen was transferred to native stigmas, and it affected seed production in one species. Although all possible steps for interference with seed production were found to be qualitatively taken, invasive pollen has probably little impact on the native community because the frequency of invasive pollen transfer to natives was low. However, pollination interactions may change with plant abundance and our study provides evidence that pollen transfer from Carpobrotus spp. to natives does occur and have the potential to affect seed production. We found the species identity of shared pollinators to be of importance, higher flower constancy and lower capacity of pollen adherence are likely to result in less invasive pollen transfer. 相似文献
48.
玉米 Y 型雄性不育系的分组问题研究初报 总被引:1,自引:0,他引:1
用专门能恢复 T 组,S 组或 C 组的专效性恢复系分别对 Y 型不育系测交,仅有 T 组的恢复系对 Y 型表现恢复。用玉米小斑病 T 小种的病菌毒素对各组不育系接种,仅 Y 型和 T 型不育系表现感病。一系列自交系对 T型与 Y 型不育系有完全相同的恢保关系。初步确定 Y 型不育系应归类于 T 组,并对 Y 型不育系的来源、不育系的分组问题 相似文献
49.
目的探讨玉米须蚕茧提取物对糖尿病小鼠模型的降糖作用.方法采用尾静脉注射小剂量的四氧嘧啶造小鼠糖尿病模型,观察不同剂量的玉米须蚕茧提取物对小鼠血糖的影响.结果玉米须蚕茧提取物对该模型有较好的降糖作用,低剂量组血糖质量浓度为(139.46±40.97)cg/L,中剂量组血糖质量浓度为(142.00±46.65)cg/L,高剂量组血糖质量浓度为(144.23±36.89)cg/L,给药组血糖均与模型组血糖有显著差别(P〈0.05).结论玉米须蚕茧提取物对本糖尿病模型有较好的治疗作用. 相似文献
50.
[Objective]The aim was to introduce T-DNA into watermelon for its molecular marker research.[Method]Based on the method of foreign DNA introduced to Arabidopsis thaliana via dipping flowers,the stigma smear was used to transfer T-DNA into watermelon and its molecular marker research was carried out.[Result]The ideal transformed species was ZXG01078 for the highest fruit setting rate and the most deviant seedlings.The best concentration of kanamycin for treating watermelon seeds was 500-700 mg/L with differences among the species.The best position was spire leaf or young leaf and the best concentration of kanamycin for treating the watermelon leaf was 4 000-8 000 mg/L with no significant difference among species.The steadily variation appearing of growing pointless and conjoined twin seedlings indicated that the normal growth had been interfered by foreign DNA in the progeny.[Conclusion]This study had provided basis for the further research on watermelon. 相似文献