全文获取类型
收费全文 | 51篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
52篇 |
出版年
2020年 | 1篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 4篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2000年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1992年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有52条查询结果,搜索用时 15 毫秒
41.
ORGANIC ACID SYNTHESIS IN RESPONSE TO EXCESS CATION ABSORPTION IN VACUOLATE AND NON-VACUOLATE SECTIONS OF CORN AND BARLEY ROOTS 总被引:2,自引:0,他引:2
- 14CO2 fixation into organic acids in tips and proximal sectionsof both corn and barley roots was studied as a function of thenature and concentration of the salt in the external solution.
- In comparison with the level of 14CO2 fixation by vacuolateproximal sections in KCI, incorporation was markedly enhancedin K2SO4 and diminished in CaCk. By contrast, non-vacuolateroot tips were indifferent to the type of external salt withrespect to UCO2 incorporation into organic acids.
- The effectof salt type on organic acid formation from 14CO2was most pronouncedat relatively high concentrations.
- The conclusion was reachedthat organic acid synthesis in responsetoexcess cation uptakeis the result of cation movement into thevacuole, and thattransport into the vacuole is mediated bythe low-affinity componentof the dual mechanisms involved inion absorption.
42.
MASAHIRO FUJISHIMA HISAHIRO SAWABE KENJI IWATSUKI 《The Journal of eukaryotic microbiology》1990,37(2):123-128
To identify the surface features of Holospora obtusa during its differentiation from the reproductive short form to the infectious long form, bacteria of four different buoyant densities were isolated by Percoll density gradient centrifugation of homogenates of host cells or isolated macronuclei, and examined with a scanning electron microscope. Bacteria of buoyant density 1.09 g/ml were reproductive short forms as well as cells at various stages in the elongation process including fully elongated ones. Bacteria of buoyant densities 1.11 g/ml and 1.13 g/ml were premature long forms and those of 1.16 g/ml were mature infectious long forms. Bacteria of buoyant density 1.09 g/ml had an entirely rough surface while those of buoyant densities 1.11 g/ml and 1.13 g/ml were smooth and had wale-like stripes on their surface. A small tapered tip was observed at one end of the bacteria of buoyant density 1.13 g/ml. Bacteria of buoyant density 1.16 g/ml had an entirely smooth surface, but one end always showed a rough surface; this locally differentiated surface of the special tip of the infectious long form may be responsible for both the nuclear and species specificities of the infectivity of H. obtusa. These observations indicate that the surface of H. obtusa changes during differentiation and the special tip develops in bacteria of buoyant density 1.13 g/ml. 相似文献
43.
This work tests two models to account for the effects of depletion of stromal inorganic phosphate (Pi ), which results in down-regulation of light capture via the exciton quenching (qE ) mechanism and has been proposed to act in feedback regulation of the light reactions. In both models, antenna down-regulation is activated by acidification of the lumen, despite the fact that linear electron flow (LEF) (and associated proton flux) is decreased upon Pi depletion. In one model, an imbalance of ATP or NADPH activates cyclic electron transfer around photosystem I (CEF1), increasing proton influx to the lumen. In the second, the effective conductivity of the CFO -CF1 ATP synthase to protons ( g H + ) is decreased, retarding proton efflux from the lumen. Sequestering of Pi by mannose infiltration increased sensitivities of qE and pmf to LEF. The effects were attributable to decreases in g H + , but not to CEF1 and were largely reversed by subsequent Pi feeding. Rapid recovery of g H + in the dark suggested that dark-labile metabolic pools are responsible for regulation of the ATP synthase. Overall, these results support models where accumulation of Benson–Calvin cycle intermediates or lowering of stromal Pi below its K M at the ATP synthase, retards proton efflux from the lumen, leading to build-up of pmf and subsequent down-regulation of photosynthetic light capture. 相似文献
44.
The queens of many social insects produce pheromones that influence the behaviour and physiology of colony members. Pheromones produced by queens have long been considered as the prime factor inhibiting the differentiation of new reproductive individuals. A volatile pheromone consisting of a blend of n‐butyl‐n‐butyrate and 2‐methyl‐1‐butanol comprises a queen pheromone that inhibits the differentiation of female neotenic reproductives (secondary queens) of a termite Reticulitermes speratus. 2‐Methyl‐1‐butanol is the first chiral molecule to be identified as a primer pheromone in social insects, which presents the intriguing question of whether enantiomeric composition plays a role in caste regulation. In the present study, we report that the (R)‐ and (S)‐enantiomers and the racemic mixture of 2‐methyl‐1‐butanol show significant inhibitory effects on the differentiation of new female neotenics in combination with n‐butyl‐n‐butyrate, whereas no significant difference in inhibitory activity is observed among them. These results suggests that termites recognize 2‐methyl‐1‐butanol as a queen signal but they do not distinguish between the stereostructures of the enantiomers. 相似文献
45.
YOSHIHIKO CHIBA YASUHIRO SHINKAWA MAKOTO YOSHII AKIRA MATSUMOTO KENJI TOMIOKA SUSUMU Y. TAKAHASHI 《Physiological Entomology》1992,17(3):213-218
Abstract. Two forms of mosquitoes in the Culex pipiens complex, C.p.pallens and C.p.molestus , were compared for the insemination-dependency of entrained female circadian activity in LD 16:8h. When virgin, Pallens is nocturnal and molestus is, in addition, diurnal. Insemination and injection of extracts of the male accessory gland affects virgin activity in that nocturnality is strengthened in both mosquitoes, and the diurnal activity of molestus is depressed. This was so whether the treatments were intra- or interspecific. These findings are compared with those already published for other mosquitoes. A coherent view is proposed that the mosquito, nocturnal/crepuscular, nocturnal and diurnal, or diurnal, has potentially a similar entrained waveform which is affected by insemination in a common way, and by lighting conditions in species specific ways. 相似文献
46.
TARO FUCHIKAWA KENTA MATSUBARA TAKAHISA MIYATAKE KENJI MATSUURA 《Physiological Entomology》2012,37(3):303-308
Daily activity rhythms are widespread characteristics among many organisms and are usually related to one or more physical environmental variables, such as light and temperature. Even organisms that are not obviously exposed to wide fluctuations in environmental variables, such as troglodytic and endogeic species, exhibit some daily activity patterns. Termites inhabit underground areas or tree trunks where little or no fluctuation in light occurs. In the present study, the activity rhythms of field colonies of the subterranean termite Reticulitermes speratus Kolbe (Blattodea: Termitidae) are examined, during all four seasons, by monitoring their acoustic emissions using a newly‐modified method. Nest temperature affects termite activity significantly during all four seasons. By contrast, no significant effect of time is observed during the different seasons, with the exception of autumn. Activity and nest temperature are negatively correlated in summer and autumn, although thay are are positively correlated during winter and spring. The greatest activity occurs at 23–25 °C. The experimental observations suggest that the activity of R. speratus termite colonies is affected mainly by ambient temperature, in a manner that is based on optimum temperature. 相似文献
47.
48.
Changes in Cell Length During Action Potentials in Chara 总被引:2,自引:0,他引:2
Changes in cell length during excitation in Chara were recordedsimultaneously with extracellular action potentials. Cells stimulatedin artificial pond water (APW) gave a diphasic change in celllength ; that is, a transient shortening followed by a delayedextension. When a cell was stimulated 13 min after aprevious shortening, the extension phase was not evident, andthe amplitude of the shortening was always larger than the previousone. Cells stimulated in moist air gave shortenings with muchlarger amplitudes and much greater durations compared with thosein APW. From such marked differences in both amplitude and durationbetween the two types of shortening it is suggested that theshortening might be caused mainly by an osmotic water movementduring excitation. Net water loss during a single action potentialwas calculated from the cell shortening to be 1.076 nl cm2per impulse or 59800 pmol cm2 per impulse, which couldbe caused by a local enhancement of ionic concentration justoutside the plasmalemma of about 0.74 mN. 相似文献
49.
MASAMI YAMAO HIDEKI SHIMIZU OSAMU NAKAMURA KENJI SOH NOBUYUKI HAMADA KATSUMI KOGA KATSUYA HAYASHI 《Development, growth & differentiation》1977,19(1):41-45
Amino acid incorporation was studied with cell-free extracts and ribosomes prepared from pupal ovaries at different ages of Bombyx mori. Poly(U)-directed 3H-phenylalanine incorporation attained a maximum rate at a certain stage of development, but soon dropped to a low level and was replaced by 3H-leucine incorporation, which was due to endogenous mRNA. The latter incorporation occurred at the stage when actual protein synthesis takes place in the ovaries. “Run-off” of the ribosomes which had a high endogenous activity resulted in an enhancement of the poly(U)-dependent activity. The results indicate that the protein synthesis in the ovary is mainly controlled at the level of mRNA. This was further supported by the fact that the relative amount of an ovarian poly(A)-containing “mRNA” fraction increased in parallel with the endogenous activity. 相似文献
50.
Flowering system of heterodichogamous Juglans ailanthifolia 总被引:1,自引:0,他引:1