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71.
The chloroplast is the hallmark organelle of plants. It performs photosynthesis and is therefore required for photoautotrophic
plant growth. The chloroplast is the most prominent member of a family of related organelles termed plastids which are ubiquitous
in plant cells. Biogenesis of the chloroplast from undifferentiated proplastids is induced by light. The generally accepted
endosymbiont hypothesis states that chloroplasts have arisen from an internalized cyanobacterial ancestor. Although chloroplasts
have maintained remnants of the ancestral genome (plastome), the vast majority of the genes encoding chloroplast proteins
have been transferred to the nucleus. This poses two major challenges to the plant cell during chloroplast biogenesis: First,
light and developmental signals must be interpreted to coordinately express genetic information contained in two distinct
compartments. This is to ensure supply and stoichiometry of abundant chloroplast components. Second, developing chloroplasts
must efficiently import nuclear encoded and cytosolically synthesized proteins. A subset of proteins, including such encoded
by the plastome, must further be sorted to the thylakoid compartments for assembly into the photosynthetic apparatus.
Received 1 September 2000; received after revision 27 October 2000; accepted 1 November 2000 相似文献
72.
Rb targets histone H3 methylation and HP1 to promoters 总被引:78,自引:0,他引:78
Nielsen SJ Schneider R Bauer UM Bannister AJ Morrison A O'Carroll D Firestein R Cleary M Jenuwein T Herrera RE Kouzarides T 《Nature》2001,412(6846):561-565
73.
74.
Jumaa H Bossaller L Portugal K Storch B Lotz M Flemming A Schrappe M Postila V Riikonen P Pelkonen J Niemeyer CM Reth M 《Nature》2003,423(6938):452-456
75.
76.
Summary
3H-serine does not label retinal neurons selectively when injected intraocularly in rabbits, as would have been expected if it had been converted to neutrotransmitter glycine. The reason is unknown, but one possibility is that the conversion was blocked during the conditions of the experiment.This work was supported by the Swedish Medical Research Council (project No. 04X-2321) and the Faculty of Medicine, University of Lund. 相似文献
77.
78.
Karine Laulagnier Charlotte Javalet Fiona J. Hemming Mathilde Chivet Gaëlle Lachenal Béatrice Blot Christine Chatellard Rémy Sadoul 《Cellular and molecular life sciences : CMLS》2018,75(4):757-773
Amyloid beta peptide (Aβ), the main component of senile plaques of Alzheimer’s disease brains, is produced by sequential cleavage of amyloid precursor protein (APP) and of its C-terminal fragments (CTFs). An unanswered question is how amyloidogenic peptides spread throughout the brain during the course of the disease. Here, we show that small lipid vesicles called exosomes, secreted in the extracellular milieu by cortical neurons, carry endogenous APP and are strikingly enriched in CTF-α and the newly characterized CTF-η. Exosomes from N2a cells expressing human APP with the autosomal dominant Swedish mutation contain Aβ peptides as well as CTF-α and CTF-η, while those from cells expressing the non-mutated form of APP only contain CTF-α and CTF-η. APP and CTFs are sorted into a subset of exosomes which lack the tetraspanin CD63 and specifically bind to dendrites of neurons, unlike exosomes carrying CD63 which bind to both neurons and glial cells. Thus, neuroblastoma cells secrete distinct populations of exosomes carrying different cargoes and targeting specific cell types. APP-carrying exosomes can be endocytosed by receiving cells, allowing the processing of APP acquired by exosomes to give rise to the APP intracellular domain (AICD). Thus, our results show for the first time that neuronal exosomes may indeed act as vehicles for the intercellular transport of APP and its catabolites. 相似文献
79.
Charlotte Froese Fischer 《复旦学报(自然科学版)》2007,46(1)
1IntroductionThe error in a non-relativistic Hartree-Fock(HF)wavefunctionis due to correlationinthe motion of theelectrons.For this reason,the error in the energy is referred to as the correlation energy.For fewelectronsystems,this correlation can beinclu… 相似文献
80.
Payne BA Wilson IJ Hateley CA Horvath R Santibanez-Koref M Samuels DC Price DA Chinnery PF 《Nature genetics》2011,43(8):806-810
There is emerging evidence that people with successfully treated HIV infection age prematurely, leading to progressive multi-organ disease, but the reasons for this are not known. Here we show that patients treated with commonly used nucleoside analog anti-retroviral drugs progressively accumulate somatic mitochondrial DNA (mtDNA) mutations, mirroring those seen much later in life caused by normal aging. Ultra-deep re-sequencing by synthesis, combined with single-cell analyses, suggests that the increase in somatic mutation is not caused by increased mutagenesis but might instead be caused by accelerated mtDNA turnover. This leads to the clonal expansion of preexisting age-related somatic mtDNA mutations and a biochemical defect that can affect up to 10% of cells. These observations add weight to the role of somatic mtDNA mutations in the aging process and raise the specter of progressive iatrogenic mitochondrial genetic disease emerging over the next decade. 相似文献