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1.
Possible involvement of jasmonates in various morphogenic events   总被引:23,自引:0,他引:23  
Jasmonates (jasmonic acid and related compounds) seem to be involved in various morphogenic events of plants, such as tuberization (potato, yam and Jerusalem artichoke), tuberous root formation (sweet potato), bulb formation (onion and garlic), determination of plant structure (soybean) and thigmomorphogenesis (coiling of tendrils of Bryonia dioica ). The involvement of jasmonates in tuberization in these plants was inferred from their ability to induce tubers in vitro, and from changes in the levels of endogenous jasmonates during the growth of the plants, which can account for the initiation of tuberization. As to potato tuberization, jasmonic acid (JA) and its methyl ester (JA-Me) have strong tuber-inducing activity. These compounds seem to exert their tuber-inducing effects by elicting the expansion of cells, because JA and JA-Me are capable of causing the expansion of cells in potato tubers. The JA-induced expansion of cells is attributable to both an increase in osmotic pressure due to the accumulation of sucrose and changes in cell wall architecture that appear to affect the extensibility of the wall. And, moreover, the synthesis of cellulose might be indispensable for the JA-induced expansion. The tuberization and the expansion of cells induced by JA always involve the reorientation of cortical microtubules (MTs), suggesting that JA controls the direction of cell expansion by changing the arrangement of MTs. However, the reorientation of MTs itself seems to be insufficient for the induction of expansion of cells.
Involvement of jasmonates in bulb formation and tuberous root formation is presumed from the fact that JA is able to induce these in vitro. The exact nature of the control that the jasmonates exert on morphogenesis remains to be elucidated.  相似文献
2.
激光辐照洋葱种子的生物学效应初探   总被引:19,自引:7,他引:12  
采用He-Ne激光和CO2激光辐照洋葱两个品种的湿种子,采用随机区组设计,重复3次,利用生物统计学的方法,从个体水平上初步考查诱变L1代的生物学效应。结果表明:在出苗率、苗高、叶数、须根长、须根数、苗重、须根重等性状表现出不同处理所引起的生物学效应差异,激光种类不同,引起须根长的变异达到5%的显著差异,激光剂量不同引起须根数变异显著,苗高和苗重的变异达到极显著。  相似文献
3.
The hypothesis that inoculation of transplants with vesicular-arbuscular mycorrhizal (VAM) fungi before planting into saline soils alleviates salt effects on growth and yield was tested on lettuce (Lactuca sativa L.) and onion (Allium cepa L.). A second hypothesis was that fungi isolated from saline soil are more effective in counteracting salt effects than those from nonsaline soil. VAM fungi from high- and low-salt soils were trap-cultured, their propagules quantified and adjusted to a like number, and added to a pasteurized soil mix in which seedlings were grown for 3–4 weeks. Once the seedlings were colonized by VAM fungi, they were transplanted into salinized (NaCl) soil. Preinoculated lettuce transplants grown for 11 weeks in the saline soils had greater shoot mass compared with nonVAM plants at all salt levels [2 (control), 4, 8 and 12 dS m–1] tested. Leaves of VAM lettuce at the highest salt level were significantly greener (more chlorophyll) than those of the nonVAM lettuce. NonVAM onions were stunted due to P deficiency in the soil, but inoculation with VAM fungi alleviated P deficiency and salinity effects; VAM onions were significantly larger at all salt levels than nonVAM onions. In a separate experiment, addition of P to salinized soil reduced the salt stress effect on nonVAM onions but to a lesser extent than by VAM inoculation. VAM fungi from the saline soil were not more effective in reducing growth inhibition by salt than those from the nonsaline site. Colonization of roots and length of soil hyphae produced by the VAM fungi decreased with increasing soil salt concentration. Results indicate that preinoculation of transplants with VAM fungi can help alleviate deleterious effects of saline soils on crop yield.  相似文献
4.
Phosphorus efficiency of plants   总被引:12,自引:2,他引:10  
Plant species differ in their P efficiency,i.e. the P content in soil needed to reach their maximum yield. The differences in external P requirements can be atributed to either a lower internal P requirement for optimum growth or higher uptake efficiency of the plant. The objective of this research was to investigate the reasons for different P efficiencies of seven plant species.Onion, ryerass, wheat, rape, spinach, tomato and bean were grown in a P-deficient subsoil fertilized with 0, 2, 5, 10, 20, 40 and 80 mg P 100 g–1. All species showed a strong yield increase due to P fertilization. To reach 80% of maximum yield onion and tomato needed 17 and 11 mg P 100 g–1 respectively, corresponding to a soil solution concentrations of 6.9 and 5.7 mol P l–1, whereas ryegrass, wheat and rape needed about 5 mg P 100g–1 corresponding to only 1.4 mol P l–1 in soil solution. These differences in external P requirement cannot be explained by differences in their internal P requirement since onion, with the highest external P requirement, only contained 0.14% P in the shoot at 80% of maximum yield, while wheat, as the most P efficient species, contained 0.28%.P efficiency was related to the uptake efficiency of the plant which is determined by both root-shoot ratio and absorption rate per unit of root (influx). Species of low efficiency such as onion, tomato and bean had low influx rates and low root-shoot ratios, whereas species of medium to high efficiency had either high influx rates (rape and spinach) or high root-shoot ratios (ryegrass and wheat). The combination of both high influx rate and high root-shoot ratio was not found in any of the species studied.  相似文献
5.
秋水仙素结合组织培养技术诱导大葱多倍体的研究   总被引:9,自引:0,他引:9  
该文研究了秋水仙素不同浓度不同时间处理大葱愈伤组织的诱导效果,发现随着处理时间和浓度的增加,愈伤组织死亡率增加,多倍体细胞诱导率在一定范围内随处理时间和浓度增加升高,但浓度超过一定量诱导率则相反,以0.06%的秋水仙素处理72h多倍体细胞诱导率最佳,且不对愈伤组织产生严重伤害,获得的变异材料与正常二倍体相比,其叶片变粗,生长迟缓,气孔器变大,经鉴定为多倍体。  相似文献
6.
离子胁迫诱导洋葱鳞茎内表皮细胞凋亡   总被引:8,自引:0,他引:8  
通过不同浓度离子胁迫诱导剂(NaCl、CaCl2)对洋葱鳞茎内表皮细胞进行不同时间的处理,发现0.1M、0.5M的NaCl和CaCl2处理2小时即可诱导出细胞凋亡现象,随处理时间延长直至10小时,细胞核凋亡的形态学变化和凋亡小体更加明显,基因组DNA降解更加梯状条带化。本实验对离子诱导的洋葱鳞茎内表皮细胞凋亡现象做了较系统的描述,为植物细胞凋亡的研究及细胞凋亡实验教学提供了经济、快捷、有效的诱导方法。  相似文献
7.
 The bulb onion, Allium cepa L., is a diploid (2n=2x=16) plant with a huge nuclear genome. Previous genetic and cytogenetic analyses have not supported a polyploid origin for onion. We developed a low-density genetic map of morphological markers, randomly amplified polymorphic DNAs (RAPD), and restriction fragment length polymorphisms (RFLP) as a tool for onion improvement and to study the genome organization of onion. A mapping population of 58 F3 families was produced from a single F1 plant from the cross of two partially inbred lines (Brigham Yellow Globe 15-23 and Alisa Craig 43). Segregations were established for restoration of male fertility in sterile cytoplasm, complementary light-red bulb color, 14 RAPDs, 110 RFLPs revealed by 90 anonymous cDNA clones, and 2 RFLPs revealed by a cDNA clone of alliinase, the enzyme responsible for the characteristic Allium flavors. Duplicated RFLP loci were detected by 21% of the clones, of which 53% were unlinked (>30 cM), 5% loosely linked (10–30 cM), and 42% tightly linked (<10 cM). This duplication frequency is less than that reported for paleopolyploids but higher than for diploid species. We observed 40% dominant RFLPs, the highest yet reported among plants. Among duplicated RFLP loci, 19% segregated as two loci each with two codominant alleles, 52% segregated as one locus with codominant alleles and one locus with only a dominant fragment, and 29% segregated as two loci with only dominant fragments. We sequenced cDNAs detecting duplicated RFLPs; 63% showed homology to known gene families (e.g., chlorophyll binding proteins, ubiquitin, or RuBISCO), and 37% were unique clones showing significant homology to known genes of low-copy number or no homology to database sequences. Duplicated RFLPs showing linkage could be due to retroviral-like sequences in adjacent coding regions or intrachromosomal, as opposed to whole genome, duplications. Previous cytological analyses and this genetic map support intrachromosomal duplication as a mechanism contributing to the huge onion genome. Received: 3 July 1997 / Accepted: 8 August 1997  相似文献
8.
激光辐照洋葱L1代的生理效应研究   总被引:7,自引:0,他引:7  
采用CO2和He-Ne两种激光的三种剂量,分别辐照两个洋葱品种的湿种子,采用生理生化的方法,从过氧化氢酶、叶绿素、总糖总量等三个方面考查研究洋葱L1各处理的生物学效应。结果表明:He-Ne激光辐照洋葱L1代的过氧化氢酶、叶绿素、总糖含量的变异大于CO2激光辐照,可作为激光诱导变洋葱育种参考。  相似文献
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