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81.
Abstract

Extract

Leguminous plants consist of two groups, amide-exporting and ureide-exporting plants. The former legumes export a large fraction of fixed-N in the form of amides (asparagine and glutamine), and the latter legumes in the form of ureides (allantoic acid and allantoin). Another characteristic of the nodules is the enrichment in 15N. There are two types of legumes: one characterized by the enrichment with 15N in N2-fixing nodules, in contrast to the other where the enrichment does not occur. The first investigation by Shearer et al. (1982) suggested that the nodules exporting fixed-N in the form of ureides were enriched in 15N unlike those exporting it in the form of amides. Soybeans, mungbean, and cowpea belong to the former group and groundnut, alfalfa, white clover to the latter. Although pea and faba bean were first classified into the latter group (Shearer et al. 1982), a recent investigation (Yoneyama 1988) showed that these nodules were also enriched in 15N.  相似文献   
82.
Abstract

The enrichment of 15N in the nodules of some N2-fixing leguminous plants is an interesting finding (Shearer et al. 1982). The extent of 15N enrichment differed depending on the plant species (Shearer et al. 1982; Yoneyama 1987) and bacterial strains (Steele et al. 1983), and in soybeans it was apparently related to the nitrogen fixation efficiency (Shearer et al. 1984)  相似文献   
83.
施肥对不同种植模式下春玉米光合特性的影响   总被引:2,自引:0,他引:2  
建立了一种密度与单作相同的超大宽窄行种植模式。通过小区试验,研究了该模式下施肥对春玉米单株叶面积、净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)及光响应曲线的影响,比较了该模式与单作模式玉米光合特性的异同。结果表明,随着施肥量的增加,Pn、Gs、Ci和单株叶面积都有增加趋势。间作玉米与单作玉米相比,玉米的单株叶面积表现为间作在生育前期小于单作,但在灌浆期及以后的生育时期单作下降较快,表现出间作明显大于单作;玉米叶片Pn生育前期单作较高,但生育后期间作明显高于单作。叶片光响应曲线及其拟合结果也表明,间作前期的最大净光合速率和表观量子效率均小于单作,生育后期大于单作。本试验表明,超大宽窄行种植模式有助于玉米生育后期光合条件的改善。  相似文献   
84.
85.
A bovine myeloid antimicrobial peptide antimicrobial peptide (BMAP‐28) is a member of the cathelicidin family and acts as a component of innate immunity. There are few reports of susceptibility difference of methicillin‐resistant Staphylococcus aureus (MRSA) and susceptible strains (MSSA) against BMAP‐28. This study aims to clarify how a few amino acid substitutions of BMAP‐28 are related to its antimicrobial activity using four analog peptides of BMAP‐28. We also compared cellular fatty acid components of MSSA and MRSA using gas chromatography. We found that a few amino acid substitutions of BMAP‐28 do not change antimicrobial activity. It was also revealed that the percentage of cis‐11‐eicosenoic acid in total detected fatty acids of MRSA was significantly higher than that of MSSA. In addition, the percentage of palmitic acid in total detected fatty acids of MRSA tended to be lower than that of MSSA. Our results will provide new information to deal with the question of differences in bacterial susceptibility against BMAP‐28.  相似文献   
86.
To detect N2-fixing bacteria in a plant without using culture methods, nifH gene segments were amplified with degenerate primers from DNA extracted from stems of sugarcane ( Saccharum officinarum L.) and leaves of pineapple ( Ananas comosus [L.] Merr.). Sequences of the nifH clones were homologous to those of bacteria in the genera Bradyrhizobium, Serratia , and Klebsiella. The bacteria with nifH sequences homologous to those of the three genera may be promising candidates for predominant endophytic diazotrophs in sugarcane and pineapple, because these sequences were commonly detected in samples from different host plants, which were collected at different locations. On the other hand, no nifH sequence related to Gluconacetobacter diazotrophicus , which is an endophytic N2-fixing bacterium and had been previously isolated from sugarcane, was detected in sugarcane. This indicates the absence or the presence of few G. diazotrophicus in the stems of the sugarcane plants used in the current study.  相似文献   
87.
Leguminous plants form nitrogen-fixing root nodules and the number of nodules is controlled by a self-regulating mechanism called autoregulation. However, signaling substances involved in nodule regulation have not been identified. In the present study, we used brassinolide, a most effective molecular species of plant hormone brassinosteroids, and brassinazole, an effective inhibitor of brassinosteroid biosynthesis to determine whether brassinolide played a role in systemic regulation of noduel formation in wild type soybean and its super-nodulating mutant. Foliar application or direct injection of brassinolide into the root base inhibited nodule formation and root development in the super-nodulating mutant (En6500), but not in the parent line (cv. Enrei). The internodes in the plants subjected to foliar application were significantly longer than those in the untreated plants. In contrast, the application of brassinazole on mature leaves or into the culture media resulted in the increase of the nodule number in Enrei. These treatments also inhibited internodal growth in Enrei. The results indicate that brassinosteroids may regulate the nodule number in soybean plants. The function of brassinosteroids for the systemic regulation of nodule formation was examined.  相似文献   
88.
Aqueous solutions of gellan gum with comparable molecular masses but with different acyl contents were investigated by atomic force microscopy and rheological measurements in the presence or absence of various cations. For a high-acyl sample, no continuous network structures were identified microscopically, except in the presence of Ca (2+), where structural inhomogeneity was the highest in terms of the height distribution of molecular assemblies. Rheological thermal hysteresis between sol-gel transitions was detected in the presence of K (+) and Ca (2+), particularly Ca (2+). The storage modulus at 20 degrees C was larger in the order Na (+) < Ca (2+) < K (+). For a low-acyl sample, continuous network structures were identified in the presence of each cation, involving greater thermal hysteresis than the corresponding data for the high-acyl sample. Structural homogeneity was the highest in the presence of K (+). Thermal hysteresis and elasticity of the system were discussed in terms of continuousness and homogeneity of network structures.  相似文献   
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