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71.
为了筛选得到对稻瘟病菌Magnaporthe grisea具有较高抑菌活性的新型化合物,根据稻瘟病菌中1,3,8-三羟基萘酚还原酶(3HNR)的结构信息,设计合成了系列2-硝基-1-芳乙烯(2a~2e)和2-溴-2-硝基-1-芳乙烯(3a,3b)目标化合物,并测试了其对3HNR和稻瘟病菌的抑制活性,同时运用分子对接方法对目标化合物与3HNR可能的结合模式进行了分析。结果表明:大部分目标化合物对3HNR都有很好的抑制作用(IC503的抑制活性最好,IC50值为0.53 μmol/L。在50 μg/mL下,目标化合物对稻瘟病菌的生长具有不同程度的抑制作用,其中2e、3a和3b的抑制率高于96%;3a和3b的EC50值分别为16.4和11.6 μg/mL。分子对接方法分析结果表明,硝基苯乙烯骨架结构与稻瘟病菌的3HNR活性空腔的氨基酸残基有较好的相互作用,其中化合物3中的溴原子可与3HNR中Tyr223和Tyr178的羟基形成氢键,从而解释了化合物3对3HNR有较好抑制作用的原因。  相似文献   
72.
To evaluate the effect of nitrogen, light, and water interaction on the biomass of cabbage the experiment was performed at three light intensities, three water stresses, and four nitrogen levels for four replicates using hydroponic technique in green house. The results showed that the biomass of the edible parts of cabbage at H1L3 was significantly higher than in weak light intensity and water stress treatments under the same nitrogen supply. An optimal yield was reached at 60% of the traditional nitrogen application in the presence of adequate high light intensity and normal water content. Decreased nitrate reductase and low capacity of nitrogen assimilation were observed when the nitrate–nitrogen (NO3-N) levels were increased from N2 to N4 with normal water content. Under severe water stress (H3), the plants have a high content of soluble sugars and a low content of amino acids in low NO3? levels (N1 to N3). Modulating the relationship between water stresses, light intensity, and nitrogen supply levels could increase the biomass and may promote the quality of a certain plant.  相似文献   
73.
Black gram (Vigna mungo L.) var. Shyam plants were raised in refined sand at four levels of molybdenum (Mo), i.e., low (0.002 µM) to excess (2 µM) for 70 days. The molybdenum deficiency symptoms appeared as interveinal chlorosis of young and middle leaves. Compared to control (0.2 µM Mo), total dry matter, seed yield and seed protein decreased at low and excess Mo. The concentration of Mo in leaves and seed as well as activity of nitrate reductase increased with an increase in Mo supply. Low and excess Mo deteriorated the quality of seeds by lowering the content of starch, sugars, protein, and nitrogen and increasing electrical conductivity of seed leachate. Molybdenum deficiency and excess both resulted in production of lightweight immature seeds, poor in vigor and germination potential. The values of sufficiency and threshold of toxicity in leaves were 0.078 and 2.15 µg Mo g?1 dry matter of black gram.  相似文献   
74.
The growth of maize seedlings was stimulated by shoot‐applied 5‐aminolevulinic acid 2 days after treatment at 90 and 120 μmol L?1. The effects of 5‐aminolevulinic acid on the activity of nitrate reductase (EC 1.6.6.2) and nitrite reductase (EC 1.7.7.1) and the chlorophyll, ammonium, heme and total free amino acid content were investigated by using maize seedlings to clarify the involvement of nitrogen metabolism and heme synthesis in the growth stimulation. 5‐Aminolevulinic acid increased the level of nitrate reductase activity at 90 μmol L?1 and the ammonium and heme content at 90 and 120 μmol L?1 2 days after treatment. The total amino acid content increased by 90 and 150 μmol L?1 5‐aminolevulinic acid 2 and 3 days after treatment, respectively. However, no significant change was observed in the activity of nitrite reductase or the chlorophyll content after the 5‐aminolevulinic acid treatment. These results suggest that the enhancement of nitrogen metabolism by nitrate reductase activation is involved in the 5‐aminolevulinic acid‐induced stimulation of maize seedling growth. The activation of nitrate reductase might be related to an increase in the heme content following the 5‐aminolevulinic acid treatment.  相似文献   
75.
木糖还原酶氧化木糖生成木糖醇,处于木糖代谢的节点位置。酿酒酵母自身不具有木糖还原酶,不能利用木糖生产乙醇。因此,可以在酿酒酵母体内引入木糖还原酶基因xyl1,完善木糖代谢流,提高酿酒酵母的木糖利用率和乙醇得率。本研究利用PCR方法,根据木糖还原酶基因xyl1序列相似的特点,设计1对引物,以休哈塔假丝酵母基因组DNA和质粒PKT0150为模板,克隆得到了木糖还原酶基因xyl1,长度为1110 bp,有3个碱基缺失,ORF位于11-982位,全长为972 bp,编码323个氨基酸,缺失的3个碱基TTG位于ORF后10、11、12位。结果表明该片段为HDYXHT-20335木糖还原酶基因序列,为构建利用木糖高产乙醇的酵母菌奠定一定基础。  相似文献   
76.
膜下滴灌对水稻根系形态及生理性状的影响   总被引:2,自引:0,他引:2  
为探明水稻在膜下滴灌灌溉方式下根系生长发生的变化,设置小区试验与传统淹灌进行对比,以粳稻品种“T-04”和“T-43”为材料,研究了膜下滴灌灌溉方式对水稻根系形态、根系氧化力和硝酸还原酶的影响.结果表明:土表下20 cm深度,膜下滴灌水稻的根系长度、表面积、体积和平均直径都高于传统淹灌,并且差异具有统计学意义.土表下40 cm,膜下滴灌对水稻根系形态影响不具有统计学意义;水稻根系氧化力都是呈先增大,后减小的趋势,水稻根系氧化力最大期因品种而异.分蘖期膜下滴灌对水稻根系氧化力的影响因品种而异,但在拔节孕穗期、齐穗期和乳熟期,膜下滴灌水稻根系氧化力高于传统淹灌,并且差异具有统计学意义,膜下滴灌水稻后期根系具有较强的抗衰老能力;膜下滴灌水稻根系硝酸还原酶活性高于传统淹灌,但在分蘖期和乳熟期的差异不具有统计学意义,在拔节孕穗期和齐穗期差异具有统计学意义.  相似文献   
77.
In alginate-assimilating bacteria, alginate is depolymerized to unsaturated monosaccharide by the actions of endolytic and exolytic alginate lyases (EC 4.2.2.3 and EC 4.2.2.11). The monosaccharide is non-enzymatically converted to 4-deoxy-l-erythro-5-hexoseulose uronic acid (DEH), then reduced to 2-keto-3-deoxy-d-gluconate (KDG) by a specific reductase, and metabolized through the Entner–Doudoroff pathway. Recently, the NADPH-dependent reductase A1-R that belongs to short-chain dehydrogenases/reductases (SDR) superfamily was identified as the DEH-reductase in Sphingomonas sp. A1. We have subsequently noticed that an SDR-like enzyme gene, flred, occurred in the genome of an alginolytic bacterium Flavobacterium sp. strain UMI-01. In the present study, we report on the deduced amino-acid sequence of flred and DEH-reducing activity of recombinant FlRed. The deduced amino-acid sequence of flred comprised 254 residues and showed 34% amino-acid identities to that of A1-R from Sphingomonas sp. A1 and 80%–88% to those of SDR-like enzymes from several alginolytic bacteria. Common sequence motifs of SDR-superfamily enzymes, e.g., the catalytic tetrad Asn-Lys-Tyr-Ser and the cofactor-binding sequence Thr-Gly-x-x-x-Gly-x-Gly in Rossmann fold, were completely conserved in FlRed. On the other hand, an Arg residue that determined the NADPH-specificity of Sphingomonas A1-R was replaced by Glu in FlRed. Thus, we investigated cofactor-preference of FlRed using a recombinant enzyme. As a result, the recombinant FlRed (recFlRed) was found to show high specificity to NADH. recFlRed exhibited practically no activity toward variety of aldehyde, ketone, keto ester, keto acid and aldose substrates except for DEH. On the basis of these results, we conclude that FlRed is the NADH-dependent DEH-specific SDR of Flavobacterium sp. strain UMI-01.  相似文献   
78.
为了探讨草莓中单脱氢抗坏血酸还原酶(Monodehydroascorbate reductase,MDHAR)和谷胱甘肽还原酶(Glutathione reductase,GR)基因的功能,采用同源克隆的方法从‘丰香’草莓中克隆得到cDNA全长序列,并采用实时定量PCR方法对其在不同组织和不同发育阶段果实中的表达模式进行分析。结果表明:草莓MDHAR基因cDNA(FaMDHAR,GenBank登录号:KP025946)全长1 305 bp,编码434个氨基酸,分子量约为47 kD,含有保守的FAD结合结构域,定位于细胞质中。GR基因cDNA(FaGR,GenBank登录号:JQ339738)开放阅读框全长1 491 bp,编码496个氨基酸,分子量为53 kD,定位于细胞质中。FaMDHAR在各组织中均有表达,在成熟果实中表达量最高,叶和花次之,根中最低;在果实发育过程中FaMDHAR在绿果期有相对较高的表达,随后急剧增加,到白熟期最高,之后下降并维持在相对稳定水平。FaGR在叶和花中表达较高,在成熟果实中较低;在果实发育过程中,表达量从小绿期呈现增加趋势,至转红果期达最高,随后逐渐下降,在成熟果实中较低。果实发育过程中酶活性变化呈现出与各自基因表达量相似的变化规律。经过4 ℃低温处理24 h后的草莓叶片中,FaMDHAR相对表达量较对照显著增加,而FaGR无显著变化。草莓中FaMDHAR和FaGR表达存在时空差异,并对低温逆境响应存在差异。  相似文献   
79.
Differences in virulence between Fusarium sulphureum and Fusarium sambucinum were compared. Changes in reactive oxygen species production and metabolism in inoculated slices of potato tubers were also compared. The result showed that Fusarium infection induced significant production of ROS, lipid peroxidation and loss of cell membrane integrity, but low activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX). Compared to F. sambucinum, F. sulphureum led larger lesion diameters on potato tubers and slices. It resulted in more superoxide anion (O2-) and earlier peak of hydrogen peroxide (H2O2), but lower activity of catalase (CAT) and APX, and accompanied with higher malondialdehyde (MDA) content and lower cell membrane integrity. These findings suggested that overproduction of ROS involved in the pathogenicity of Fusarium in potato tubers.  相似文献   
80.
以陕西省黄陵县轩辕庙院内千年树龄黄帝手植柏(古侧柏)嫩枝为外植体进行茎段组织培养试验研究。经过初代培养和继代增殖培养,研究了不同植物生长调节剂种类及浓度、活性炭在组培各阶段的作用,并测定不同年龄段侧柏组织培养前后的硝酸还原酶活性。结果表明:最适启动培养基为1/2MS+6-BA 0.2 mg/L+NAA 0.1 mg/L+椰乳100 mL/L,适宜的继代培养基为1/2或1/4MS+ 6-BA 0.4 mg/L+NAA 0.1 mg/L+椰乳100 mL/L;活性炭对增殖无显著作用;古侧柏组织培养后硝酸还原酶活性可达到幼嫩水平。  相似文献   
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