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11.
12.
Rosemarie Swanson 《Bulletin of mathematical biology》1984,46(2):187-203
The structure of the genetic code is related to a Gray code, which is a plausible theoretical model for an amino acid code.
The proposed model implies that the most important factor in shaping the code was the effects of mistakes in translation,
not effects of mutations. Another possible implication is that the preservation of stiffness and flexibility at appropriate
places in a protein chain is as important in protein structure as the appropriate placement of hydrophilic (external) and
hydrophobic (internal) residues. Other results are a simple conceptualization of the relationships among the 20 amino acids
and their relations to their codons. The detailed relationships are summarized in the following ‘similarity alphabet’: ala,
thr, gly, pro, ser; asp, asn, glu, gln, lys; his, arg, trp, tyr, phe; leu, met, ile, val, cys; (ATGPS DNEQK HRWYF LMIVC in
the one-letter code). This alphabet falls into four groups of amino acids: small, external, large, internal. The approximate
relation of the groups to their codons is expressed as: the first base of a codon controls size—a purine means a small amino
acid, a pyrimidine means large; the middle base controls cloisterednes—purine means external, pyrimidine means internal. These
relationships express the minimum change principle upon which the code appears to be founded. 相似文献
13.
Sultana H Rivero F Blau-Wasser R Schwager S Balbo A Bozzaro S Schleicher M Noegel AA 《Traffic (Copenhagen, Denmark)》2005,6(10):930-946
Data from mutant analysis in yeast and Dictyostelium indicate a role for the cyclase-associated protein (CAP) in endocytosis and vesicle transport. We have used genetic and biochemical approaches to identify novel interacting partners of Dictyostelium CAP to help explain its molecular interactions in these processes. Cyclase-associated protein associates and interacts with subunits of the highly conserved vacuolar H(+)-ATPase (V-ATPase) and co-localizes to some extent with the V-ATPase. Furthermore, CAP is essential for maintaining the structural organization, integrity and functioning of the endo-lysosomal system, as distribution and morphology of V-ATPase- and Nramp1-decorated membranes were disturbed in a CAP mutant (CAP bsr) accompanied by an increased endosomal pH. Moreover, concanamycin A (CMA), a specific inhibitor of the V-ATPase, had a more severe effect on CAP bsr than on wild-type cells, and the mutant did not show adaptation to the drug. Also, the distribution of green fluorescent protein-CAP was affected upon CMA treatment in the wildtype and recovered after adaptation. Distribution of the V-ATPase in CAP bsr was drastically altered upon hypo-osmotic shock, and growth was slower and reached lower saturation densities in the mutant under hyper-osmotic conditions. Taken together, our data unravel a link of CAP with the actin cytoskeleton and endocytosis and suggest that CAP is an essential component of the endo-lysosomal system in Dictyostelium. 相似文献
14.
L De Colibus AF Sonnen KJ Morris CA Siebert P Abrusci J Plitzko V Hodnik M Leippe E Volpi G Anderluh RJ Gilbert 《Structure (London, England : 1993)》2012,20(9):1498-1507
Pore-forming proteins insert from solution into membranes to create lesions, undergoing a structural rearrangement often accompanied by oligomerization. Lysenin, a pore-forming toxin from the earthworm Eisenia fetida, specifically interacts with sphingomyelin (SM) and may confer innate immunity against parasites by attacking their membranes to form pores. SM has important roles in cell membranes and lysenin is a popular SM-labeling reagent. The structure of lysenin suggests common ancestry with other pore-forming proteins from a diverse set of eukaryotes and prokaryotes. The complex with SM shows the mode of its recognition by a protein in which both the phosphocholine headgroup and one acyl tail are specifically bound. Lipid interaction studies and assays using viable target cells confirm the functional reliance of lysenin on this form of SM recognition. 相似文献
15.
16.
Abraitiene A Zhao Y Hammond R 《Biochemical and biophysical research communications》2008,368(3):470-475
Transient expression of engineered reporter RNAs encoding an intron-containing green fluorescent protein (GFP) from a Potato virus X-based expression vector previously demonstrated the nuclear targeting capability of the 359 nucleotide Potato spindle tuber viroid (PSTVd) RNA genome. To further delimit the putative nuclear-targeting signal, PSTVd subgenomic fragments were embedded within the intron, and recombinant reporter RNAs were inoculated onto Nicotiana benthamiana plants. Appearance of green fluorescence in leaf tissue inoculated with PSTVd-fragment-containing constructs indicated shuttling of the RNA into the nucleus by fragments as short as 80 nucleotides in length. Plant-to-plant variation in the timing of intron removal and subsequent GFP fluorescence was observed; however, earliest and most abundant GFP expression was obtained with constructs containing the conserved hairpin I palindrome structure and embedded upper central conserved region. Our results suggest that this conserved sequence and/or the stem-loop structure it forms is sufficient for import of PSTVd into the nucleus. 相似文献
17.
18.
Sucrose (2,5–1000 mmol l–1), labeled with [14C]sucrose, was taken up by the xylem when supplied to one end of a 30-cm-long leaf strip of Zea mays L. cv. Prior. The sugar was loaded into the phloem and transported to the opposite end, which was immersed in diluted Hoagland's nutrient solution. When the Hoagland's solution at the opposite end was replaced by unlabeled sucrose solution of the same molarity as the labeled one, the two solutions met near the middle of the leaf strip, as indicated by radioautographs. In the dark, translocation of 14C-labeled assimilates was always directed away from the site of sucrose application, its distance depending on sugar concentration and translocation time. When sucrose was applied to both ends of the leaf strip, translocation of 14C-labeled assimilates was directed toward the lower sugar concentration. In the light, transport of 14-C-labeled assimilates can be directed (1) toward the morphological base of the leaf strip only (light effect), (2) toward the base and away from the site of sucrose application (light and sucrose effect), or (3) away from the site of sucrose application independent of the (basipetal or acropetal) direction (sucrose effect). The strength of a sink, represented by the darkened half of a leaf strip, can be reduced by applying sucrose (at least 25 mmol l–1) to the darkened end of the leaf strip. However, equimolar sucrose solutions applied to both ends do not affect the strength of the dark sink. Only above 75 mmol l–1 sucrose was the sink effect of the darnened part of the leaf strip reduced. Presumably, increasing the sucrose concentration replenishes the leaf tissue more rapidly, and photosynthates from the illuminated part of the leaf strip are imported to a lesser extent by the dark sink.Supported by Deutsche Forschungsgemeinschaft 相似文献
19.
C. A. Morris C. D. K. Bottema N. G. Cullen S. M. Hickey A. K. Esmailizadeh B. D. Siebert W. S. Pitchford 《Animal genetics》2010,41(6):589-596
A QTL study of live animal and carcass traits in beef cattle was carried out in New Zealand and Australia. Back‐cross calves (385 heifers and 398 steers) were generated, with Jersey and Limousin backgrounds. This paper reports on weights of eight organs (heart, liver, lungs, kidneys, spleen, gastro‐intestinal tract, fat, and rumen contents) and 12 fat composition traits (fatty acid (FA) percentages, saturated and monounsaturated FA subtotals, and fat melting point). The New Zealand cattle were reared and finished on pasture, whilst Australian cattle were reared on grass and finished on grain for at least 180 days. For organ weights and fat composition traits, 10 and 12 significant QTL locations (P < 0.05), respectively, were detected on a genome‐wide basis, in combined‐sire or within‐sire analyses. Seven QTL significant for organ weights were found at the proximal end of chromosome 2. This chromosome carries a variant myostatin allele (F94L), segregating from the Limousin ancestry, and this is a positional candidate for the QTL. Ten significant QTL for fat composition were found on chromosomes 19 and 26. Fatty acid synthase and stearoyl‐CoA desaturase (SCD1), respectively, are positional candidate genes for these QTL. Two FA QTL found to be common to sire groups in both populations were for percentages of C14:0 and C14:1 (relative to all FAs) on chromosome 26, near the SCD1 candidate gene. 相似文献
20.
Gillian A. Lowe Garth Lipps Roger C. Gibson Sharon Halliday Amrie Morris Nelson Clarke Rosemarie N. Wilson 《PloS one》2014,9(4)