全文获取类型
收费全文 | 146篇 |
免费 | 18篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2012年 | 11篇 |
2011年 | 8篇 |
2010年 | 10篇 |
2009年 | 15篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 6篇 |
2005年 | 14篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1954年 | 2篇 |
排序方式: 共有164条查询结果,搜索用时 15 毫秒
121.
Extracts of stems of growing shoots of Populus deltoides and P. trichocarpa, and developing capsules of P. deltoides were analysed for gibberellins (GAs) by gas chromatography-mass spectrometry. The following known GAs were identified by comparison of their Kovats retention indices (KRIs) and mass spectra with those of standards: GA1, GA8, GA9, GA19, GA20, 16 beta,17-dihydro-17-hydroxy GA20, GA23, GA28, GA29, GA34, GA44, and GA97. Several of these have not been previously reported from Populus. In addition, two new GAs were identified as 12 beta-hydroxy GA53 (GA127) and 16 beta,17-dihydro-17-hydroxy GA53 and their structures were confirmed by partial synthesis. Evidence was found of 16,17-dihydro-16,17-dihydroxy GA9, 16,17-dihydro-16,17-dihydroxy GA12, 12-hydroxy GA14, and GA34-catabolite by comparison of mass spectra and KRIs with published data. Several putative GAs (hydroxy- and dihydroxy-GA12-like) were also found. The catabolites of active GAs or of key precursors, hydroxylated at C-2 in stems and either C-2, C-12, C-17, or C-16,17 in capsules, were the major proportion of the GAs. 相似文献
122.
Background
Based on sensitivity analysis of the MacDonald-Ross model, it has long been argued that the best way to reduce malaria transmission is to target adult female mosquitoes with insecticides that can reduce the longevity and human-feeding frequency of vectors. However, these analyses have ignored a fundamental biological difference between mosquito adults and the immature stages that precede them: adults are highly mobile flying insects that can readily detect and avoid many intervention measures whereas mosquito eggs, larvae and pupae are confined within relatively small aquatic habitats and cannot readily escape control measures. 相似文献123.
124.
Sequences throughout the basic beta-1,3-glucanase mRNA coding region are targets for homology dependent post-transcriptional gene silencing 总被引:3,自引:0,他引:3
125.
A strong linear correlation was found between the log-transformed load and retention of nitrogen and phosphorus in riparian buffer zones (r=0.99 and 0.997, respectively). Analyses of N and P budgets in four riparian forests of varying age (two grey alder stands in Estonia and two riparian deciduous forests in USA) show a significant efficiency. Despite the different input load (72.9–110.4 kg N ha−1 year−1 and 2.5–3.0 kg P ha−1 year−1), the outputs into streams from the alder stands systems were comparably low (9.0–13.2 and 0.38–0.62 kg ha−1 year−1). The older forests from the USA showed less efficiency. Plant uptake of both N and P in younger stands was significantly higher than in older forests. Methods to determine the buffer zones' and buffer strips' width and their efficiency are presented. The testing of efficiency assessment in a watershed in Estonia demonstrated an expected efficiency of buffers. 相似文献
126.
Gibberellins (GA) A1, A19, and A20 were identified in shoot cylinders containing the apical meristems from sorghum (Sorghum bicolor L.). Extracts were purified by sequential SiO2 partition chromatography and reversed-phase C18 high performance liquid chromatography and biologically active (dwarf rice cv Tan-ginbozu microdrop assay) fractions were subjected to gas chromatography-selected ion monitoring. Based on the use of [3H]GA and [2H](d2)GA internal standards, amounts of GA1, GA19, and GA20 were estimated to be 0.7, 8.8, and 1.5 namograms per gram dry weight of tissue, respectively. 相似文献
127.
Seed and 4-chloroindole-3-acetic acid regulation of gibberellin metabolism in pea pericarp. 总被引:5,自引:1,他引:4 下载免费PDF全文
In this study, we investigated seed and auxin regulation of gibberellin (GA) biosynthesis in pea (Pisum sativum L.) pericarp tissue in situ, specifically the conversion of [14C]GA19 to [14C]GA20. [14C]GA19 metabolism was monitored in pericarp with seeds, deseeded pericarp, and deseeded pericarp treated with 4-chloroindole-3-acetic acid (4-CI-IAA). Pericarp with seeds and deseeded pericarp treated with 4-CI-IAA continued to convert [14C]GA19 to [14C]GA20 throughout the incubation period (2-24 h). However, seed removal resulted in minimal or no accumulation of [14C]GA20 in pericarp tissue. [14C]GA29 was also identified as a product of [14C]GA19 metabolism in pea pericarp. The ratio of [14C]GA29 to [14C]GA20 was significantly higher in deseeded pericarp (with or without exogenous 4-CI-IAA) than in pericarp with seeds. Therefore, conversion of [14C]GA20 to [14C]GA29 may also be seed regulated in pea fruit. These data support the hypothesis that the conversion of GA19 to GA20 in pea pericarp is seed regulated and that the auxin 4-CI-IAA can substitute for the seeds in the stimulation of pericarp growth and the conversion of GA19 to GA20. 相似文献
128.
Genetic Regulation of Development in Sorghum bicolor: V. The ma(3) Allele Results in Gibberellin Enrichment 总被引:1,自引:0,他引:1 下载免费PDF全文
Sorghum bicolor genotypes, near isogenic with different alleles at the third maturity locus, were compared for development, for responsiveness to GA3 and a GA synthesis inhibitor, and occurrence and concentrations of endogenous GAs, IAA, and ABA. At 14 days the genotype 58M (ma3Rma3R) exhibited 2.5-fold greater culm height, 1.75-fold greater total height, and 1.38-fold greater dry weight than 90M (ma3ma3) or 100M (Ma3Ma3). All three genotypes exhibited similar shoot elongation in response to GA3, and 58M showed GA3-mediated hastening of floral initiation when harvested at day 18 or 21. Both 90M and 100M had exhibited hastening of floral initiation by GA3 previously, at later application dates. Tetcyclacis reduced height, promoted tillering, and delayed flowering of 58M resulting in plants which were near phenocopies of 90M and 100M. Based on bioassay activity, HPLC retention times, cochromatography with 2H2-labeled standards on capillary column GC and matching mass spectrometer fragmentation patterns (ions [m/z] and relative abundances), GA1, GA19, GA20, GA53, and GA3 were identified in extracts of all three genotypes. In addition, based on published Kovats retention index values and correspondence in ion masses and relative abundances, GA44 and GA17 were detected. Quantitation was based on recovery of coinjected, 2H2-labeled standards. In 14 day-old-plants, total GA-like bioactivity and GA1 concentrations (nanograms GA/gram dry weight) were two- to six-fold higher in 58M than 90M and 100M in leaf blades, apex samples, and whole plants while concentrations in culms were similar. Similar trends occurred if data were expressed on a per plant basis. GA1 concentrations for whole plants were about two-fold higher in 58M than 90M and 100M from day 7 to day 14. Concentrations of ABA and IAA did not vary between the genotypes. The results indicate the mutant allele ma3R causes a two- to six-fold increase in GA1 concentrations, does not result in a GA-receptor or transduction mutation and is associated with phenotypic characteristics that can be enhanced by GA3 and reduced by GA synthesis inhibitor. These observations support the hypothesis that the allele ma3R causes an overproduction of GAs which results in altered leaf morphology, reduced tillering, earlier flowering, and other phenotypic differences between 58M and 90M or 100M. 相似文献
129.
Masayoshi Nakayama Hisakazu Yamane Noboru Murofushi Nobutaka Takahashi Lewis N. Mander Hideharu Seto 《Journal of Plant Growth Regulation》1991,10(1-4):115-119
[2H2]Gibberellin A24 (GA24) and [2H4]-GA9 were applied to the apices of normal-type cucumber (Cucumis sativus L. cv. Yomaki) seedlings treated with uniconazole, an inhibitor of GA biosynthesis. The metabolites from these feeds were identified by full-scan gas chromatography-mass spectrometry (GC-MS) to confirm the conversions of [2H2]GA24 to [2H2]GA9 and of [2H4]GA9 to [2H4]GA4. The results show that GA4 is biosynthesized from GA24 via GA9. In a cucumber hypocotyl elongation bioassay using cv. Yomaki, prohexadione (DOCHC), an inhibitor of 2-oxoglutaratedependent dioxygenase, inhibited the hypocotyl elongation caused by application of GA9, while DOCHC enhanced the elongation caused by application of GA4. These results indicate that GA4 is a physiologically active GA and that the activity of GA9 is due to its conversion to GA4 in cucumber shoots. 相似文献
130.
Masayoshi Nakayama Hisakazu Yamane Noboru Murofushi Nobutaka Takahashi Lewis N. Mander Hideharu Seto 《Journal of Plant Growth Regulation》1991,10(1):115-119
[2H2]Gibberellin A24 (GA24) and [2H4]-GA9 were applied to the apices of normal-type cucumber (Cucumis sativus L. cv. Yomaki) seedlings treated with uniconazole, an inhibitor of GA biosynthesis. The metabolites from these feeds were identified by full-scan gas chromatography-mass spectrometry (GC-MS) to confirm the conversions of [2H2]GA24 to [2H2]GA9 and of [2H4]GA9 to [2H4]GA4. The results show that GA4 is biosynthesized from GA24
via GA9. In a cucumber hypocotyl elongation bioassay using cv. Yomaki, prohexadione (DOCHC), an inhibitor of 2-oxoglutaratedependent dioxygenase, inhibited the hypocotyl elongation caused by application of GA9, while DOCHC enhanced the elongation caused by application of GA4. These results indicate that GA4 is a physiologically active GA and that the activity of GA9 is due to its conversion to GA4 in cucumber shoots. 相似文献