全文获取类型
收费全文 | 257篇 |
免费 | 14篇 |
专业分类
271篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 18篇 |
2012年 | 17篇 |
2011年 | 14篇 |
2010年 | 17篇 |
2009年 | 9篇 |
2008年 | 16篇 |
2007年 | 16篇 |
2006年 | 10篇 |
2005年 | 17篇 |
2004年 | 14篇 |
2003年 | 5篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1967年 | 3篇 |
1966年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有271条查询结果,搜索用时 15 毫秒
1.
2.
Massimo Maffei Marco Mucciarelli Silvano Scannerini 《Biochemical Systematics and Ecology》1993,21(8):765-784
The effect of some environmental factors on the lipid metabolism was studied in two chemotypes of Rosmarinus officinalis L. Epicuticular hydrocarbons (EH), epicuticular fatty acids (EFA), whole leaf fatty acids (WLFA) and essential oils (EO) were extracted and analysed by GC-MS during winter 1991–1992 and related to temperature and moisture variations. Leaf fresh and dry wts were determined along with some morphophysiological parameters such as specific leaf weight (SLW) and specific leaf area (SLA). Leaf areas were calculated by image analysis and statistically processed as for chemical data. The results indicated that in R. officinalis the response to some environmental factors, with particular reference to temperature and moisture, was an increase in epicuticular hydrocarbons and a decrease in epicuticular fatty acids, leaf fatty acids and essential oils. Qualitative changes in the chemical composition of the above lipid classes were found to be correlated with temperature changes. From a chemosystematic viewpoint, a clear separation between the two chemotypes was achieved only when epicuticular hydrocarbons and essential oils were considered as chemosystematic characters. 相似文献
3.
Lamberto Maffei Enrico Meschini Floriano Papi 《Ethology : formerly Zeitschrift fur Tierpsychologie》1983,62(2):151-156
Since birds use the earth's magnetic field for compass orientation when astronomical cues are lacking and it has recently been suggested that the pineal body is part of their magnetic compass, test releases have been performed in overcast conditions with pigeons deprived of the pineal body. On the whole, both experimental and control birds were capable of homeward orientation, though the bearings of experimental were rather more scattered. No differences in homing speed or success were recorded. Thus, the pineal body does not appear to play an important role in the homing of pigeons. 相似文献
4.
Naresh Loudya Douglas P F Maffei Jocelyn Bdard Sabri Mohd Ali Paul F Devlin R Paul Jarvis Enrique Lpez-Juez 《The Plant cell》2022,34(8):3028
Chloroplast biogenesis requires synthesis of proteins in the nucleocytoplasm and the chloroplast itself. Nucleus-encoded chloroplast proteins are imported via multiprotein translocons in the organelle’s envelope membranes. Controversy exists around whether a 1-MDa complex comprising TIC20, TIC100, and other proteins constitutes the inner membrane TIC translocon. The Arabidopsis thaliana cue8 virescent mutant is broadly defective in plastid development. We identify CUE8 as TIC100. The tic100cue8 mutant accumulates reduced levels of 1-MDa complex components and exhibits reduced import of two nucleus-encoded chloroplast proteins of different import profiles. A search for suppressors of tic100cue8 identified a second mutation within the same gene, tic100soh1, which rescues the visible, 1 MDa complex-subunit abundance, and chloroplast protein import phenotypes. tic100soh1 retains but rapidly exits virescence and rescues the synthetic lethality of tic100cue8 when retrograde signaling is impaired by a mutation in the GENOMES UNCOUPLED 1 gene. Alongside the strong virescence, changes in RNA editing and the presence of unimported precursor proteins show that a strong signaling response is triggered when TIC100 function is altered. Our results are consistent with a role for TIC100, and by extension the 1-MDa complex, in the chloroplast import of photosynthetic and nonphotosynthetic proteins, a process which initiates retrograde signaling.Complementary mutations in TIC100 of the chloroplast inner envelope membrane cause reductions or corrective improvements in chloroplast protein import, and highlight a signaling role.IN A NUTSHELLBackground: Plants harvest energy from the sun and CO2 from the air and convert them into the energy-rich molecules they, and eventually us, are made of. Plants do this, photosynthesis, in bodies called chloroplasts inside their cells. Chloroplasts, made of protein and membrane material, were, before plants evolved, free-living bacteria, but the synthesis of most of their proteins occurs outside them, using information carried by the cell’s nuclear DNA, so most proteins have to be brought into developing chloroplasts, across the double membrane surrounding them, through dedicated, selective channels, formed by TOC (outer) and TIC (inner envelope) proteins. The identity of those channels matters as it helps determine versions of chloroplasts suited for particular environments. Which TIC proteins constitute the inner envelope channel has been a matter of controversy.Question: A mutant Arabidopsis plant called cue8 is slow-to-green (young leaves begin almost white) and shows delayed chloroplast and plant development. We looked for the molecular identity of the CUE8 gene. We also caused further mutations in this mutant and searched whether any corrected the defects in cue8.Findings: We found the mutated gene causing the cue8 defects is the TIC100 gene. This is one essential component of the “TIC 1-MDa complex,” one of the two versions of the TIC import complex under debate. That complex is made of several proteins, all present at reduced levels in cue8. In laboratory assays in which proteins are imported into isolated chloroplasts, cue8 performed worse than normal plants for a photosynthetic and a housekeeping chloroplast protein. A corrective, “suppressor” mutant was identified, and it carried a second mutation in TIC100, one physically complementary to the first one. Both the single and the double (suppressed) mutant still were slow-to-green, which evidences a signaling role for import defects to the nucleus, making photosynthetic genes active or not.Next steps: Surprisingly the grasses, including the cereals, have one core protein of the TIC 1 MDa complex but not the rest (including TIC100). We don’t know how their TIC channels operate. We also need to learn how the information on the defect in protein import, which occurs at the chloroplast envelope, is relayed to the cell’s nucleus (but we do have some clues). 相似文献
5.
6.
7.
8.
V KW Wong T Li B YK Law E DL Ma N C Yip F Michelangeli C KM Law M M Zhang K YC Lam P L Chan L Liu 《Cell death & disease》2013,4(7):e720
Autophagy is an important cellular process that controls cells in a normal homeostatic state by recycling nutrients to maintain cellular energy levels for cell survival via the turnover of proteins and damaged organelles. However, persistent activation of autophagy can lead to excessive depletion of cellular organelles and essential proteins, leading to caspase-independent autophagic cell death. As such, inducing cell death through this autophagic mechanism could be an alternative approach to the treatment of cancers. Recently, we have identified a novel autophagic inducer, saikosaponin-d (Ssd), from a medicinal plant that induces autophagy in various types of cancer cells through the formation of autophagosomes as measured by GFP-LC3 puncta formation. By computational virtual docking analysis, biochemical assays and advanced live-cell imaging techniques, Ssd was shown to increase cytosolic calcium level via direct inhibition of sarcoplasmic/endoplasmic reticulum Ca2+ ATPase pump, leading to autophagy induction through the activation of the Ca2+/calmodulin-dependent kinase kinase–AMP-activated protein kinase–mammalian target of rapamycin pathway. In addition, Ssd treatment causes the disruption of calcium homeostasis, which induces endoplasmic reticulum stress as well as the unfolded protein responses pathway. Ssd also proved to be a potent cytotoxic agent in apoptosis-defective or apoptosis-resistant mouse embryonic fibroblast cells, which either lack caspases 3, 7 or 8 or had the Bax-Bak double knockout. These results provide a detailed understanding of the mechanism of action of Ssd, as a novel autophagic inducer, which has the potential of being developed into an anti-cancer agent for targeting apoptosis-resistant cancer cells. 相似文献
9.
Biochemical and Histochemical Localization of Monoterpene Biosynthesis in the Glandular Trichomes of Spearmint (Mentha spicata) 总被引:1,自引:0,他引:1 下载免费PDF全文
The primary monoterpene accumulated in the glandular trichomes of spearmint (Mentha spicata) is the ketone (−)-carvone which is formed by cyclization of the C10 isoprenoid intermediate geranyl pyrophosphate to the olefin (−)-limonene, hydroxylation to (−)-trans-carveol and subsequent dehydrogenation. Selective extraction of the contents of the glandular trichomes indicated that essentially all of the cyclase and hydroxylase activities resided in these structures, whereas only about 30% of the carveol dehydrogenase was located here with the remainder located in the rest of the leaf. This distribution of carveol dehydrogenase activity was confirmed by histochemical methods. Electrophoretic analysis of the partially purified carveol dehydrogenase from extracts of both the glands and the leaves following gland removal indicated the presence of a unique carveol dehydrogenase species in the glandular trichomes, suggesting that the other dehydrogenase found throughout the leaf probably utilizes carveol only as an adventitious substrate. These results demonstrate that carvone biosynthesis takes place exclusively in the glandular trichomes in which this natural product accumulates. 相似文献
10.
Silencing of aphid genes by dsRNA feeding from plants 总被引:4,自引:0,他引:4