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排序方式: 共有251条查询结果,搜索用时 250 毫秒
41.
A new fluorescent chemosensor for cadmium(II) based on a pyrene‐appended piperidone derivative and its β‐cyclodextrin complex
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Sumathi Poomalai Tamil Selvan Govindaraj Suganthi Soundrapandian Mosae Selvakumar Paulraj Israel Vijayaraj Muthu Vijayan Enoch 《Luminescence》2018,33(3):538-544
We report, in this article, a piperidin‐4‐one derivative carrying pyrenyl fluorescent reporter groups which acts as a Cd2+ ion sensor. The compound is synthesized and characterized using IR and NMR spectral techniques. The compound forms an inclusion complex with β‐cyclodextrin. It selectively binds to Cd2+ ions in water and aqueous β‐cyclodextrin media. The stoichiometry of the host–guest complex of the compound with β‐cyclodextrin is 1:2. The ligand–metal ion binding stoichiometry is 1:1 both in water and in β‐cyclodextrin. The linear concentration range of detection of the metal ion is reported. Cyclodextrin complex formation does not affect the metal ion selectivity of the compound. 相似文献
42.
Uchiyama Hirofumi Iwai Atsushi Dohra Hideo Ohnishi Toshiyuki Kato Tatsuya Park Enoch Y. 《Applied microbiology and biotechnology》2018,102(10):4467-4475
Applied Microbiology and Biotechnology - Killer toxin resistant 6 (Kre6) and its paralog, suppressor of Kre null 1 (Skn1), are thought to be involved in the biosynthesis of cell wall... 相似文献
43.
Use of gap repair in fission yeast to obtain novel alleles of specific genes. 总被引:3,自引:0,他引:3
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We have adapted a method for making libraries of mutations in any specific gene for use in the fission yeast Schizosaccharomyces pombe . This elegant and simple method consists of PCR amplification of the gene of interest, followed by co-transformation of fission yeast with the PCR fragment and a linearized plasmid vector prepared such that the ends of the vector share DNA sequence with the ends of the PCR fragment. Homologous recombination between the vector and the PCR fragment occurs at a high frequency and results in a collection of yeast transformants, most harboring a mutated allele of the original gene within the vector of choice. This library can then be screened or selected for phenotypes of interest. 相似文献
44.
Effects of molybdate, tungstate, and selenium compounds on formate dehydrogenase and other enzyme systems in Escherichia coli 总被引:20,自引:12,他引:8
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The role of selenium and molybdenum in the metabolism of Escherichia coli was explored by growing cells in a simple salts medium and examining the metabolic consequences of altering the concentration of molybdenum and selenium compounds in the medium. The addition of tungstate increased the molybdate deficiency of this medium, as reflected by lowered levels of enzyme systems previously recognized to require compounds of molybdenum and selenium for their formation [formate-dependent oxygen reduction, formate dehydrogenase (FDH) (EC 1.2.2.1), and nitrate reductase (EC 1.9.6.1)]. The requirement for selenium and molybdenum appears to be unique to the enzymes of formate and nitrate metabolism since molybdate- and selenite-deficient medium had no effect on the level of several dehydrogenase and oxidase systems, for which the electron donors were reduced nicotinamide adenine dinucleotide, succinate, d- or l-lactate, and glycerol. In addition, no effect was observed on the growth rate or cell yield with any carbon source tested (glucose, glycerol, dl-lactate, acetate, succinate, and l-malate) when the medium was deficient in molybdenum and selenium. dl-Selenocystine was about as effective as selenite in stimulating the formation of formate dehydrogenase, whereas dl-selenomethionine was only 1% as effective. In aerobic cells, an amount of FDH was formed such that 3,200 or 3,800 moles of formate were oxidized per min per mole of added selenium (added as dl-selenocystine or selenite, respectively). 相似文献
45.
Enoch S. Huang Patrice Koehl Michael Levitt Rohit V. Pappu Jay W. Ponder 《Proteins》1998,33(2):204-217
The ab initio folding problem can be divided into two sequential tasks of approximately equal computational complexity: the generation of native-like backbone folds and the positioning of side chains upon these backbones. The prediction of side-chain conformation in this context is challenging, because at best only the near-native global fold of the protein is known. To test the effect of displacements in the protein backbones on side-chain prediction for folds generated ab initio, sets of near-native backbones (≤ 4 Å Cα RMS error) for four small proteins were generated by two methods. The steric environment surrounding each residue was probed by placing the side chains in the native conformation on each of these decoys, followed by torsion-space optimization to remove steric clashes on a rigid backbone. We observe that on average 40% of the χ1 angles were displaced by 40° or more, effectively setting the limits in accuracy for side-chain modeling under these conditions. Three different algorithms were subsequently used for prediction of side-chain conformation. The average prediction accuracy for the three methods was remarkably similar: 49% to 51% of the χ1 angles were predicted correctly overall (33% to 36% of the χ1+2 angles). Interestingly, when the inter-side-chain interactions were disregarded, the mean accuracy increased. A consensus approach is described, in which side-chain conformations are defined based on the most frequently predicted χ angles for a given method upon each set of near-native backbones. We find that consensus modeling, which de facto includes backbone flexibility, improves side-chain prediction: χ1 accuracy improved to 51–54% (36–42% of χ1+2). Implications of a consensus method for ab initio protein structure prediction are discussed. Proteins 33:204–217, 1998. © 1998 Wiley-Liss, Inc. 相似文献
46.
Enoch G. Achigan-Dako Jörg Fuchs Adam Ahanchede Frank R. Blattner 《Plant Systematics and Evolution》2008,276(1-2):9-19
The occurrence and extent of genome size variation within species is controversially discussed and thorough analyses are rare. Given the large morphological variation in Lagenaria siceraria (bottle gourds) and its wide distribution in Africa we here analysed (1) the genome size variation within cultivars of L. siceraria, (2) the correlation between genome size and morphological traits, and (3) the geographical patterns of DNA content within the species. We measured 2C-values of 366 individuals from 117 accessions of L. siceraria (2n = 22) from Africa, America and Asia via flow cytometry with propidium iodide as DNA stain. We found that 2C-value in L. siceraria (0.683–0.776 pg/2C) is about two times lower than previously reported and varies by about 12% among all accessions. Moreover, our results indicated a clear correlation of genome size with two different seed or usage types and with growing elevations in West Africa. Within the seed types genome size varies by 6.6 and 7.5%, respectively. The genome size differences in seed types of L. siceraria might indicate differences in their evolutionary history and necessitates a re-evaluation of the phylogenetic relationships within L. siceraria while the correlation between 2C-value and the elevation of the collecting sites might indicate an adaptation of genome size to an unknown ecological parameter connected to altitude. 相似文献
47.
In this study, human α-1,4-N-acetylglucosaminyltransferase (α4GnT) fused with GFPuv (GFPuv-α4GnT) was expressed using both a transformed cell system and silkworm larvae. A Tn-pXgp-GFPuv-α4GnT cell line, isolated after expression vector transfection, produced 106 mU/ml of α4GnT activity in suspension culture.
When Bombyx mori nucleopolyhedrovirus containing a GFPuv-α4GnT fusion gene (BmNPV-CP
−/GFPuv-α4GnT) bacmid was injected into silkworm larvae, α4GnT activity in larval hemolymph was 352 mU/ml, which was 3.3-fold higher
than that of the Tn-pXgp-GFPuv-α4GnT cell line. With human calnexin (CNX) or human immunoglobulin heavy chain-binding protein (BiP, GRP78) coexpressed under
the control of the ie-2 promoter, α4GnT activity in larval hemolymph increased by 1.4–2.0-fold. Moreover, when BmNPV-CP
−/GFPuv-α4GnT bacmid injection was delayed for 3 h after BmNPV-CP
−/CNX injection, the α4GnT activity increased significantly to 922 mU/ml, which was 8.7-fold higher than that of the Tn-pXgp-GFPuv-α4GnT cell line. Molecular chaperone assisted-expression in silkworm larvae using the BmNPV bacmid is a promising tool for
recombinant protein production. This system could lead to large-scale production of more complex recombinant proteins. 相似文献
48.
Three forms of recombinant protein complexes comprising the human prorenin (hPro) and (pro)renin receptor (hPRR) (hPRR/prorenin)
were successfully expressed in the silkworm larvae using Bombyx mori nucleopolyhedrovirus (BmNPV) bacmids. They were localized in the fat body cells and formed a prorenin-bound hPRR complex.
The expressed levels of hPro and hPRR were similar judging from Western blotting. The hPRR/prorenin complex containing 40 μg
of hPRR (yield, 43%) and 30 μg of hPro (yield, 34%) was purified from 15 silkworm larvae by a series of purification using
anti-FLAG and Strep-Tactin affinity chromatography. The renin activity of the purified hPRR/prorenin complex was 3.8-fold
that of the mixture of hPRR and hPro expressed individually in vitro judging from the renin assay. These results show that
the unstable transmembrane protein, hPRR, was coexpressed stably with ligand, hPro, and formed a stable protein, hPRR/prorenin
complex that showed a high catalytic active form. 相似文献
49.
Ogata Makoto Nakajima Makoto Kato Tatsuya Obara Takakiyo Yagi Hirokazu Kato Koichi Usui Taichi Park Enoch Y 《BMC biotechnology》2009,9(1):1-13
Background
Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine, with therapeutic applications in several autoimmune and inflammatory diseases. Oral administration of this cytokine alone, or in combination with disease-associated autoantigens could confer protection form the onset of a specific autoimmune disease through the induction of oral tolerance. Transgenic plants are attractive systems for production of therapeutic proteins because of the ability to do large scale-up at low cost, and the low maintenance requirements. They are highly amenable to oral administration and could become effective delivery systems without extensive protein purification. We investigated the ability of tobacco plants to produce high levels of biologically-active viral and murine IL-10.Results
Three different subcellular targeting strategies were assessed in transient expression experiments, and stable transgenic tobacco plants were generated with the constructs that yielded the highest accumulation levels by targeting the recombinant proteins to the endoplasmic reticulum. The best yields using this strategy in T1 plants were 10.8 and 37.0 μg/g fresh leaf weight for viral and murine IL-10, respectively. The recombinant proteins were purified from transgenic leaf material and characterized in terms of their N-glycan composition, dimerization and biological activity in in vitro assays. Both molecules formed stable dimers, were able to activate the IL-10 signaling pathway and to induce specific anti-inflammatory responses in mouse J774 macrophage cells.Conclusion
Tobacco plants are able to correctly process viral and murine IL-10 into biologically active dimers, therefore representing a suitable platform for the production for these cytokines. The accumulation levels obtained are high enough to allow delivery of an immunologically relevant dose of IL-10 in a reasonable amount of leaf material, without extensive purification. This study paves the way to performing feeding studies in mouse models of autoimmune diseases, that will allow the evaluation the immunomodulatory properties and effectiveness of the viral IL-10 in inducing oral tolerance compared to the murine protein. 相似文献50.
Alexandre Hainard Natalia Tiberti Xavier Robin Veerle Lejon Dieudonné Mumba Ngoyi Enock Matovu John Charles Enyaru Catherine Fouda Joseph Mathu Ndung'u Frédérique Lisacek Markus Müller Natacha Turck Jean-Charles Sanchez 《PLoS neglected tropical diseases》2009,3(6)