全文获取类型
收费全文 | 304篇 |
免费 | 64篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 11篇 |
2012年 | 12篇 |
2011年 | 12篇 |
2010年 | 23篇 |
2009年 | 9篇 |
2008年 | 14篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 11篇 |
2003年 | 3篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 13篇 |
1998年 | 20篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 17篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1968年 | 3篇 |
1964年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有368条查询结果,搜索用时 31 毫秒
1.
2.
Stitt M 《Plant physiology》1987,84(2):201-204
The control of the fructose 2,6-bisphosphate (Fru2,6P2) concentration and its possible role in controlling carbohydrate synthesis and degradation are discussed. This regulator metabolite is involved in the fine tuning of photosynthetic metabolism, and in controlling photosynthetic partitioning, and may also be involved in the response to hormones, wounding, and changing water relations. Study of the mechanisms controlling Fru2,6P2 concentrations could reveal insights into how these responses are mediated. However, the detailed action of Fru2,6P2 requires more attention, especially in respiratory metabolism where the background information about the compartmentation of metabolism between the plastid and cytosol is still inadequate, and the potential role of pyrophosphate has to be clarified. 相似文献
3.
Richard C. Leegood Carlos A. Labate Steven C. Huber H. Ekkehard Neuhaus Mark Stitt 《Planta》1988,176(1):117-126
Glycerol induced a limitation on photosynthetic carbon assimilation by phosphate when supplied to leaves of barley (Hordeum vulgare L.) and spinach (Spinacia oleracea L.). This limitation by phosphate was evidenced by (i) reversibility of the inhibition of photosynthesis by glycerol by feeding orthophosphate (ii) a decrease in light-saturated rates of photosynthesis and saturation at a lower irradiance, (iii) the promotion of oscillations in photosynthetic CO2 assimilation and in chlorophyll fluorescence, (iv) decreases in the pools of hexose monophosphates and triose phosphates and increases in the ratio of glycerate-3-phosphate to triose phosphate, (v) decreased photochemical quenching of chlorophyll fluorescence, and increased non-photochemical quenching, specifically of the component which relaxed rapidly, indicating that thylakoid energisation had increased. In barley there was a massive accumulation of glycerol-3-phosphate and an increase in the period of the oscillations, but in spinach the accumulation of glycerol-3-phosphate was comparatively slight. The mechanism(s) by which glycerol feeding affects photosynthetic carbon assimilation are discussed in the light of these results.Abbreviations Chl
chlorophyll
- C
i
intercellular concentration of CO2
- P
phosphate
- PGA
glycerate-3-phosphate
- Pi
orthophosphate
- triose-P
sum of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate 相似文献
4.
5.
6.
7.
The febrile responses of Sprague-Dawley rats to semi-purified human endogenous pyrogen were studied at a thermoneutral ambient temperature (26 degrees C) and in the cold (3 degrees C). It was found that while rats developed typical monophasic febrile responses at thermoneutrality, febrile responses were absent in the cold-exposed rats. Experiments were conducted to determine whether this lack of febrile responses in cold-exposed rats was due to an inability of these animals to generate or retain heat in the cold. Thermogenesis and vasoconstriction were stimulated in cold-exposed rats by selectively cooling the hypothalamus, using chronically implanted thermodes. It was shown that, using this stimulus, metabolic rate could be increased by more than 50 percent and body temperature could be driven up at a rate of 5 degrees C/hour in rats exposed to the cold. Therefore, it was concluded that the lack of febrile responses of cold-exposed rats to pyrogen is in no way due to a physical or physiological inability to retain heat. Instead, it appears that in some manner cold exposure suppresses the sensitivity or responsiveness of the rat to pyrogenic stimuli. 相似文献
8.
9.
The febrile responses of male Sprague-Dawley rats to a semi-purified endogenous pyrogen (EP) derived from human monocytes are markedly enhanced 3 days after the animals are intravenously injected with a variety of immunoadjuvants. The present study was designed to investigate the site within the body at which these substances act to produce this febrile-enhancing phenomenon. Stainless steel microinjection cannula guide tubes were implanted within the region of the organum vasculosum lamina terminalis (OVLT) of the rats and control febrile dose-response curves to EP were established. Minute quantities of the immunoadjuvants zymosan, lipopolysaccharide endotoxin, and the synthetic adjuvant peptide, muramyl dipeptide, were microinjected into the OVLT region and 3 days later, the febrile responses of the animals were retested. In each case the febrile response elicited by a standard dose of EP was more than doubled, the slope of the fever dose-response curve was tripled, and the dose threshold was lowered by a factor of four to five. These responses are identical with those produced when much larger amounts of these immunoadjuvants are injected intravenously, and, thus, we conclude that the site of action of these substances in enhancing fever in response to EP resides in or near the OVLT region. It is proposed that EP stimulates a type of reticuloendothelial cell residing within the OVLT to release prostaglandin E, which in turn crosses the blood-brain barrier to effect the changes in the thermoregulatory neurons of the preoptic anterior hypothalamic area that result in fever. 相似文献
10.
The molecular evolution of mammalian Y-linked DNA sequences is of special
interest because of their unique mode of inheritance: most Y- linked
sequences are clonally inherited from father to son. Here we investigate
the use of Y-linked sequences for phylogenetic inference. We describe a
comparative analysis of a 515-bp region from the male sex- determining
locus, Sry, in 22 murine rodents (subfamily Murinae, family Muridae),
including representatives from nine species of Mus, and from two additional
murine genera--Mastomys and Hylomyscus. Percent sequence divergence was
< 0.01% for comparisons between populations within a species and was
0.19%-8.16% for comparisons between species. Our phylogenetic analysis of
12 murine taxa resulted in a single most- parsimonius tree that is highly
concordant with phylogenies based on mitochondrial DNA and allozymes. A
total evidence tree based on the combined data from Sry, mitochondrial DNA,
and allozymes supports (1) the monophyly of the subgenus Mus, (2) its
division into a Palearctic group (M. musculus, M. domesticus, M.
spicilegus, M. Macedonicus, and M. spretus) and an Oriental group (M.
cookii++, M. cervicolor, and M. caroli), and (3) sister-group relationships
between M. spicilegus and M. macedonicus and between M. cookii and M.
cervicolor. We argue that Y- chromosome DNA sequences represent a valuable
new source of characters for phylogenetic inference.
相似文献