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911.
Metabolomics for the Authentication of Natural Extracts Used in Flavors and Fragrances: the Case Study of Violet Leaf Absolutes from Viola odorata 下载免费PDF全文
Laure Saint‐Lary Céline Roy Jean‐Philippe Paris Jean‐François Martin Olivier P. Thomas Xavier Fernandez 《化学与生物多样性》2016,13(6):737-747
Natural extracts used in fine fragrances (alcoholic perfumes) are rare and precious. As such, they represent an interesting target for fraudulent practices called adulterations. Absolutes, important materials used in the creation of perfumes, are obtained by organic solvent extraction of raw plant materials. Because the nonvolatile part of these natural extracts is not normalized and scarcely reported, highlighting potential adulterations present in this fraction appears highly challenging. For the first time, we investigated the use of nontargeted UHPLC‐ToFMS metabolomics for this purpose, considering Viola odorata l ., a plant largely used in the perfume industry, as a model. Significant differences in the metabolic fingerprints of the violet leaf absolutes were evidenced according to geographical locations, and/or adulterations. Additionally, markers of the geographical origin were detected through their molecular weight/most probable molecular formula and retention time, while adulterations were statistically validated. In this study, we thus clearly demonstrated the efficiency of UHPLC‐ToFMS‐based metabolomics in accelerating both the identification of the origin of raw materials as well as the search for potential adulterations in absolutes, natural products of high added value. 相似文献
912.
Souria Malki Gilles De Luca Marie Laure Fardeau M. Rousset Jean Pierre Belaich Z. Dermoun 《Archives of microbiology》1997,167(1):38-45
The presence of one periplasmic [NiFe] hydrogenase, one periplasmic [Fe] hydrogenase, and one cytoplasmic NADP-reducing hydrogenase
has been previously established in Desulfovibrio fructosovorans. In the present work, marker-exchange mutagenesis was performed to determine the function of the tetrameric NADP-reducing
hydrogenase encoded by the hndA, B, C, and D genes. The mutations performed were not lethal to the cells, although the H2-dependent NADP reduction was completely abolished. The double-mutated DM4 (ΔhynABC, ΔhndD) strain was still able to grow on hydrogen plus sulfate as the sole energy source. The growth may have occurred under these
culture conditions because of the presence of the remaining [Fe] hydrogenase. The cells grew differently on various substrates
depending on whether fructose, lactate, or pyruvate was used in the presence of sulfate. The (hnd mutant growth rates were 25–70% lower than those of the wild-type strain, although the molar growth yield remained unchanged.
By contrast, mutants devoid of both [NiFe] hydrogenase and NADP-reducing hydrogenase had 24-38% lower growth yields and showed
a corresponding drop in the growth rates. We concluded that each of the three hydrogenases may contribute to the energy supply
in D. fructosovorans and that the loss of one enzyme might be compensated for by another. However, the loss of two hydrogenases affected the phosphorylation
accompanying the metabolism of fructose, lactate, and pyruvate.
Received: 17 September 1996 / Accepted: 5 November 1996 相似文献
913.
The O-glycosylated Stalk Domain Is Required for Apical Sorting of Neurotrophin Receptors in Polarized MDCK Cells 总被引:15,自引:2,他引:13 下载免费PDF全文
Charles Yeaman Annick H. Le Gall Anne N. Baldwin Laure Monlauzeur Andre Le Bivic Enrique Rodriguez-Boulan 《The Journal of cell biology》1997,139(4):929-940
Delivery of newly synthesized membrane-spanning proteins to the apical plasma membrane domain of polarized MDCK epithelial cells is dependent on yet unidentified sorting signals present in the luminal domains of these proteins. In this report we show that structural information for apical sorting of transmembrane neurotrophin receptors (p75NTR) is localized to a juxtamembrane region of the extracellular domain that is rich in O-glycosylated serine/threonine residues. An internal deletion of 50 amino acids that removes this stalk domain from p75NTR causes the protein to be sorted exclusively of the basolateral plasma membrane. Basolateral sorting stalk-minus p75NTR does not occur by default, but requires sequences present in the cytoplasmic domain. The stalk domain is also required for apical secretion of a soluble form of p75NTR, providing the first demonstration that the same domain can mediate apical sorting of both a membrane-anchored as well as secreted protein. However, the single N-glycan present on p75NTR is not required for apical sorting of either transmembrane or secreted forms. 相似文献
914.
Dehaye Laure Duval Manuel Viguier Delphine Yaxley Jennifer Job Dominique 《Plant molecular biology》1997,35(5):605-621
Besides biotin-dependent carboxylases, which play key roles in basic metabolism, SBP65 (seed biotinylated protein of 65 kDa of apparent molecular mass), an atypical biotinylated protein, has been described in pea plants. This seed-specific protein is devoid of any carboxylase activity, and shares many physiological and molecular features with late embryogenesis-abundant (Lea) proteins. In a first step toward understanding the role of this peculiar protein, we have demonstrated the role of abscisic acid (ABA) and of the osmotic environment on its expression using northern blot analysis from immature embryos cultured in vitro and germinating mature seeds. Moreover, the cloning and characterization of its gene (referred to as sbp gene) allowed us to define various potential cis-acting elements within the promoter region to account for the observed strict seed-specific expression. The results described in this paper are consistent with a model in which ABA regulates, at least in part, expression of this gene. However, unlike most lea genes, ABA regulation of the sbp gene seems to occur in a very restricted fashion, being confined only to particular stages of embryo development. Such a strict spatial and temporal expression pattern is dependent on the osmotic environment of the developing embryos and on tissue-specific factors, presumably preventing biotin depletion in cells requiring this essential cofactor for basic metabolic activity. 相似文献
915.
Randy D. Blakely Laure Ory-Lavollee Reid C. Thompson Joseph T. Coyle† 《Journal of neurochemistry》1986,47(4):1013-1019
This study was undertaken to explore in synaptosomal preparations the disposition of N-acetyl-aspartyl-glutamate (NAAG), an endogenous acidic dipeptide neurotransmitter candidate. Radiolabel from N-acetyl-aspartyl[3H]glutamate was taken up rapidly into an osmotically sensitive compartment by rat brain synaptosomal preparations in a sodium-, temperature-, and time-dependent manner. HPLC analysis of the accumulated radiolabel indicated that the bulk of the tritium cochromatographed with glutamic acid and not with NAAG. In contrast, [14C]NAAG, labeled on the N-terminal acetate, was not taken up by the synaptosomal preparation. All effective inhibitors of synaptosomal, Na+-dependent [3H]glutamate uptake were found to exhibit similar potency in inhibiting uptake of tritium derived from [3H]NAAG. However, certain alpha-linked acidic dipeptides, structurally similar to NAAG, as well as the potent convulsant quisqualic acid inhibited synaptosomal transport of [3H]NAAG but were ineffective as inhibitors of [3H]glutamate transport. Together with a demonstration of disparities between the regional accumulation of radiolabel from [3H]NAAG and high-affinity [3H]glutamate uptake, these data suggest the presence in brain of a specific peptidase targeting carboxy-terminal glutamate-containing dipeptides that may be coupled to the Na+-dependent glutamate transporter. These findings provide a possible mechanism for NAAG inactivation subsequent to its release from nerve endings. 相似文献
916.
Summary In Fanconi anemia (FA) cells the duration of the G2 phase of the cell cycle prolonged. Such a slowing of the G2 phase can be induced in normal cells by irradiation with rays during S phase, which also further increases the duration of G2 in FA cells. The addition of caffeine during the last 7h of culture shortens the G2 phase in both nonirradiated and irradiated FA cells. In nonirradiated normal cells it may have no effect or may increase G2 phase duration, but in irradiated normal reduces the slowing of G2 induced by the radiation. This suggests that FA cells recognize and repair preexisting DNA lesions during G2 phase and that caffeine inhibits this process. The principal anomaly in FA may be a deficient repair during S phase, as manifest in the prolonged postreplication repair period during G2 phase required to repair the larger number of lesions passing through S phase. 相似文献
917.
The radius of gyration of crotamine is determined by the small angle x-ray scattering technique. Several molecular solutions have been studied to correct for concentration effects. The apparent molecular radius of gyration is also determined as a function of pH. An important change between pH 9.5 and 12.5 is attributed to a dominant effect of molecular aggregation. 相似文献
918.
Mulualem T. Kassa Sabrina Haas Edgar Schliephake Clare Lewis Frank M. You Curtis J. Pozniak Ilona Krämer Dragan Perovic Andrew G. Sharpe Pierre R. Fobert Michael Koch Ian L. Wise Paul Fenwick Simon Berry James Simmonds Delphine Hourcade Patrice Senellart Laure Duchalais Olivier Robert Jutta Förster Julian B. Thomas Wolfgang Friedt Frank Ordon Cristobal Uauy Curt A. McCartney 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2016,129(8):1507-1517
919.
Molecular and Cellular Analysis of Human Immunodeficiency Virus-Induced Apoptosis in Lymphoblastoid T-Cell-Line-Expressing Wild-Type and Mutated CD4 Receptors 总被引:2,自引:1,他引:1 下载免费PDF全文
Laure Moutouh Jrme Estaquier Douglas D. Richman Jacques Corbeil 《Journal of virology》1998,72(10):8061-8072
We have previously shown that the presence of the CD4 cytoplasmic tail is critical for human immunodeficiency virus (HIV)-induced apoptosis (J. Corbeil, M. Tremblay, and D. D. Richman, J. Exp. Med. 183:39–48, 1996). We have pursued our investigation of the role of the CD4 transduction pathway in HIV-induced apoptosis. To do this, wild-type and mutant forms of the CD4 cytoplasmic tail were stably expressed in the lymphoblastoid T-cell line A2.01. Apoptosis was prevented when CD4 truncated at residue 402 was expressed; however, cells expressing mutated receptors that do not associate with p56lck (mutated at the dicysteine motif and truncated at residue 418) but which conserved proximal domains of the cytoplasmic tail underwent apoptosis like wild-type CD4. The differences between wild-type and mutated receptors in the induction of apoptosis were not related to levels of p56lck or NF-κB activation. Initial signaling through the CD4 receptor played a major role in the sensitization of HIV-infected T cells to undergo apoptosis. Incubation of HIV-infected cells with monoclonal antibody (MAb) 13B8-2, which binds to CD4 in a region critical for dimerization of the receptor, prevented apoptosis without inhibiting HIV replication. Moreover, the apoptotic process was not related to Fas-Fas ligand interaction; however, an antagonistic anti-Fas MAb (ZB-4) enhanced apoptosis in HIV-infected cells without inducing apoptosis in uninfected cells. These observations demonstrate that CD4 signaling mediates HIV-induced apoptosis by a mechanism independent of Fas-Fas ligand interaction, does not require p56lck signaling, and may involve a critical region for CD4 dimerization. 相似文献
920.
Charalambos Magoulas Ada Loverre-Chyurlia Sumaia Abukashawa Laure Bally-Cuff Donal A. Hickey 《Journal of molecular evolution》1993,36(3):234-242
Summary Previous studies have demonstrated that the expression of the -amylase gene is repressed by dietary glucose in Drosophila melanogaster. Here, we show that the -amylase gene of a distantly related species, D. virilis, is also subject to glucose repression. Moreover, the cloned amylase gene of D. virilis is shown to be glucose repressible when it is transiently expressed in D. melanogaster larvae. This cross-species, functional conservation is mediated by a 330-bp promoter region of the D. virilis amylase gene. These results indicate that the promoter elements required for glucose repression are conserved between distantly related Drosophila species. A sequence comparison between the amylase genes of D. virilis and D. melanogaster shows that the promoter sequences diverge to a much greater degree than the coding sequences. The amylase promoters of the two species do, however, share small clusters of sequence similarity, suggesting that these conserved cis-acting elements are sufficient to control the glucose-regulated expression of the amylase gene in the genus Drosophila.Offprint requests to: D.A. Hickey 相似文献