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排序方式: 共有290条查询结果,搜索用时 15 毫秒
31.
Ferreira LS Rodrigues MS Converti A Sato S Carvalho JC 《Biotechnology and bioengineering》2012,109(2):444-450
Arthrospira platensis was cultivated in tubular photobioreactor in order to evaluate growth and biomass production at variable photosynthetic photon flux density (PPFD = 60, 120, and 240 μmol photons m(-2)s(-1)) and employing three different systems for cell circulation, specifically an airlift, a motor-driven pumping and a pressurized system. The influence of these two independents variables on the maximum cell concentration (X(m)), cell productivity (P(x)), nitrogen-to-cell conversion factor (Y(X/N) ), photosynthetic efficiency (PE), and biomass composition (total lipids and proteins), taken as responses, was evaluated by analysis of variance. The statistical analysis revealed that the best combination of responses' mean values (X(m) = 4,055 mg L(-1), P(x) = 406 mg L(-1)day(-1), Y(X/N) = 5.07 mg mg(-1), total lipids = 8.94%, total proteins = 30.3%, PE = 2.04%) was obtained at PPFD = 120 μmol photons m(-2)s(-1); therefore, this light intensity should be considered as the most well-suited for A. platensis cultivation in this photobioreactor configuration. The airlift system did not exert any significant positive statistical influence on the responses, which suggests that this traditional cell circulation system could successfully be substituted by the others tested in this work. 相似文献
32.
Oliveira RP Basso LC Junior AP Penna TC Del Borghi M Converti A 《Biological trace element research》2012,145(1):71-80
Most of the metals released from industrial activity, among them are cadmium (Cd) and nickel (Ni), inhibit the productivity
of cultures and affect microbial metabolism. In this context, the aim of this work was to investigate the capacity of sugar
cane vinasse to mitigate the adverse effects of Cd and Ni on cell growth, viability, budding rate and trehalose content of
Saccharomyces cerevisiae, likely because of adsorption and chelating action. For this purpose, the yeast was grown batch-wise in YED medium supplemented
with selected amounts of vinasse and Cd or Ni. The negative effects of Cd and Ni on S. cerevisiae growth and the mitigating one of sugar cane vinasse were quantified by an exponential model. Without vinasse, the addition
of increasing levels of Cd and Ni reduced the specific growth rate, whereas in its presence no reduction was observed. Consistently
with the well-proved toxicity of both metals, cell viability and budding rate progressively decreased with increasing their
concentration, but in the presence of vinasse the situation was remarkably improved. The trehalose content of S. cerevisiae cells followed the same qualitative behavior as cell viability, even though the negative effect of both metals on this parameter
was stronger. These results demonstrate the ability of sugar cane vinasse to mitigate the toxic effects of Cd and Ni. 相似文献
33.
The objective of the paper is to show the very important biophysical concepts that have been developed with polysaccharides.
In particular, an attempt will be made to relate “a posteriori” the fundamental aspects, both experimental and theoretical,
with some industrial applications of polysaccharide-based materials. The overview of chain conformational aspects includes
relationships between topological features and local dynamics, exemplified for some naturally occurring carbohydrate polymers.
Thus, by using simulation techniques and computational studies, the physicochemical properties of aqueous solutions of polysaccharides
are interpreted. The relevance of conformational disorder–order transitions, chain aggregation, and phase separation to the
underlying role of the ionic contribution to these processes is discussed. We stress the importance of combining information
from analysis of experimental data with that from statistical–thermodynamic models for understanding the conformation, size,
and functional stability of industrially important polysaccharides. The peculiar properties of polysaccharides in industrial
applications are summarized for the particularly important example of nanoparticles production, a field of growing relevance
and scientific interest. 相似文献
34.
Identification of olive (Olea europaea) seed and pulp proteins by nLC-MS/MS via combinatorial peptide ligand libraries 总被引:1,自引:0,他引:1
Esteve C D'Amato A Marina ML García MC Citterio A Righetti PG 《Journal of Proteomics》2012,75(8):2396-2403
Different types of extraction protocols are described for identifying proteins in seed and pulp of olive (Olea europea), by employing both conventional extraction methods and capture with ProteoMiner as well as with in house-made combinatorial peptide ligand libraries (HM-CPLLs) at pH 7.4 and at pH 2.2. Thanks to the use of CPLLs, able to dramatically amplify the signal of low-abundance species, a quite large number of compounds has been indeed identified: 61 in the seed (vs. only four reported in current literature) and 231 in the pulp (vs. 56 described so far), the deepest investigation up to the present of the olive proteome. In the seed, it highlights the presence of seed storage proteins, oleosins and histones. In the pulp, the allergenic thaumatin-like protein (Ole e 13) was confirmed, among the other 231, as the most abundant protein in the olive pulp. The present research has also been undertaken with the aim of identifying proteins in olive oil and ascertaining the relative contribution of seed and pulp proteins in their presence, if any, in oils. 相似文献
35.
* Cadmium (Cd) stress increases cell metabolic demand for sulfur, reducing equivalents, and carbon skeletons, to sustain phytochelatin biosynthesis for Cd detoxification. In this condition the induction of potentially acidifying anaplerotic metabolism in root tissues may be expected. For these reasons the effects of Cd accumulation on anaplerotic metabolism, glycolysis, and cell pH control mechanisms were investigated in maize (Zea mays) roots. * The study compared root apical segments, excised from plants grown for 24 h in a nutrient solution supplemented, or not, with 10 microM CdCl(2), using physiological, biochemical and (31)P-nuclear magnetic resonance (NMR) approaches. * Cadmium exposure resulted in a significant decrease in both cytosolic and vacuolar pH of root cells and in a concomitant increase in the carbon fluxes through anaplerotic metabolism leading to malate biosynthesis, as suggested by changes in dark CO2 fixation, metabolite levels and enzyme activities along glycolysis, and mitochondrial alternative respiration capacity. This scenario was accompanied by a decrease in the net H(+) efflux from the roots, probably related to changes in plasma membrane permeability. * It is concluded that anaplerotic metabolism triggered by Cd detoxification processes might lead to an imbalance in H(+) production and consumption, and then to cell acidosis. 相似文献
36.
Analysis of grape berry cell wall proteome: a comparative evaluation of extraction methods 总被引:1,自引:0,他引:1
Negri AS Prinsi B Scienza A Morgutti S Cocucci M Espen L 《Journal of plant physiology》2008,165(13):1379-1389
Different methods were tested for the extraction of proteins from the cell wall-enriched fraction (CWEf) obtained from a sample formed by skin and seeds of ripe berries of Vitis vinifera L. cv. Cabernet Sauvignon. The CWEf was isolated using a disruptive approach that involves tissue homogenization and precipitation by centrifugation. To extract proteins, the CWEf was treated with CaCl(2) and LiCl in two successive steps or, alternatively, with phenol. The efficiency of the protocols was evaluated by measuring protein yield and by analyzing two-dimensional gel electrophoresis (2-DE) gels for the highest detectable spot number and the greatest spot resolution. The phenol method was also adopted for the extraction of proteins from the cytosolic fraction (CYf). The comparison of 2-DE reference maps of protein extracts from CWEf and CYf indicated the presence of both common traits and unique characteristics. To survey this aspect some spots detected in both fractions or present in only one fraction were analyzed by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Of the 47 spots identified, some were found to be cell wall proteins, while others were proteins not traditionally considered as localized in the apoplastic space. The data presented here provide initial information regarding the apoplastic proteome of grape berry tissues, but also raise the issue of the technical problems that characterize the isolation of cell wall proteins from these very hardy tissues. 相似文献
37.
Orelle C Gubellini F Durand A Marco S Lévy D Gros P Di Pietro A Jault JM 《Biochemistry》2008,47(8):2404-2412
ATP-binding cassette (ABC) transporters are involved in the transport of a wide variety of substrates, and ATP-driven dimerization of their nucleotide binding domains (NBDs) has been suggested to be one of the most energetic steps of their catalytic cycle. Taking advantage of the propensity of BmrA, a bacterial multidrug resistance ABC transporter, to form stable, highly ordered ring-shaped structures [Chami et al. (2002) J. Mol. Biol. 315, 1075-1085], we show here that addition of ATP in the presence of Mg2+ prevented ring formation or destroyed the previously formed rings. To pinpoint the catalytic step responsible for such an effect, two classes of hydrolysis-deficient mutants were further studied. In contrast to hydrolytically inactive glutamate mutants that behaved essentially as the wild-type, lysine Walker A mutants formed ring-shaped structures even in the presence of ATP-Mg. Although the latter mutants still bound ATP-Mg, and even slowly hydrolyzed it for the K380R mutant, they were most likely unable to undergo a proper NBD dimerization upon ATP-Mg addition. The ATP-driven dimerization step, which was still permitted in glutamate mutants and led to a stable conformation suitable to monitor the growth of 2D crystals, appeared therefore responsible for destabilization of the BmrA ring structures. Our results provide direct visual evidence that the ATP-induced NBD dimerization triggers a conformational change large enough in BmrA to destabilize the rings, which is consistent with the assumption that this step might constitute the "power stroke" for ABC transporters. 相似文献
38.
Attilio Converti Adriana Del Borghi Raffaella Gandolfi Alessandra Lodi Francesco Molinari Emilio Palazzi 《Biotechnology and bioengineering》2002,77(2):232-237
The reactivity and thermostability of a novel mycelium-bound carboxylesterase from lyophilized cells of Aspergillus oryzae are explored in organic solvent. Ethanol acetylation was selected as reference esterification reaction. High carboxylesterase activity cells were used as biocatalyst in batch esterification tests at 12.5 < S(o) < 125 mmol L(-1), 5.0 < X(o) < 30 g L(-1), 0.49 < log P < 4.5 and 30 < T < 80 degrees C, as well as in residual activity tests after incubation at 40 < T < 90 degrees C. The starting rates of product formation were used to estimate with the Arrhenius model the apparent activation enthalpies of the enzymatic reaction (29-33 kJ mol(-1)), the reversible unfolding (56-63 kJ mol(-1)), and the irreversible denaturation (22 kJ mol(-1)) of the biocatalyst. 相似文献
39.
F. Geuna H. Hartings A. Scienza 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(3):375-383
The degree of polymorphism present in 5′ untranslated regions of stilbene synthase (StSy)-like loci was assessed. A ligation-mediated polymerase chain reaction (LM-PCR) cloning strategy was adopted to isolate sequences
located immediately upstream of StSy coding regions. Among several clones, 13 randomly chosen fragments were analyzed at the
sequence level. Four of the analyzed fragments appeared of particular interest. Two carried sequences reminiscent of micro-satellites,
while the remaining fragments contained direct repeats. Oligonucleotides constructed against the specific DNA sequence of
these clones disclosed a complex banding pattern when used in polymerase chain reaction (PCR)-analysis of 22 ancient varieties
of grapevine. A total of 40 polymorphic bands could be identified and used to calculate coefficients of genetic similarity
(GS) between varieties. GS values were used in cluster analysis to differentiate the 22 varieties. The data obtained are in
good agreement with available information concerning the relationships between the varieties considered. This suggests the
use of the method we have developed in fingerprinting studies of Vitis vinifera germ plasma.
Received: 11 April 1996 / Accepted: 14 March 1997 相似文献