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981.
模体是蛋白质二级结构上的一种特征序列,激酶底物通常具有一类特征性的模体,识别底物模体对鉴定激酶底物具有重要意义。为了快速鉴定激酶底物模体,将全细胞蛋白质酶解液作为肽段文库的来源,采用碱性磷酸酶去除肽段的固有磷酸化后构建了用于筛选激酶底物模体的肽段文库。该肽段文库是大量非磷酸化肽段的混合物,将此混合肽段与酪蛋白激酶2和三磷酸腺苷作用30 min后,通过固定化金属离子亲和色谱法富集磷酸化肽段,采用反相液相色谱-串联质谱分析,成功地鉴定到472条非冗余底物肽段,包含451个非冗余磷酸化位点,并由此得到底物模体S/T-D/E-x-D/E。该法能够快速准确地筛选出激酶底物模体,对研究激酶-底物识别以及信号转导过程具有重要意义。 相似文献
982.
The unfolding of bovine heart cytochrome c induced by urea and guanidine hydrochloride was first studied through intrinsic fluorescence emission spectra and fluorescence phase diagram and the results showed that both of them separately followed a two‐state model. As the simplest sample of the unfolding of protein molecules induced by denaturants, an equation was presented to show the effect of the denaturant concentrations in denaturation solution on the residual activity ratios of bovine heart cytochrome c in their two‐state unfolding. There are two characteristic unfolding parameters K and m in this equation. The former is the thermodynamic equilibrium constant of the unfolding of bovine heart cytochrome c induced by denaturants, the latter is the number of denaturant molecules associated with a bovine heart cytochrome c molecule during the unfolding procedure, and through them the distribution and transition of native and completely unfolded bovine heart cytochrome c conformations under different concentrations of urea or guanidine hydrochloride in denaturation solution can be accurately described. 相似文献
983.
Fluorescence spectroscopy, Fourier transform infrared (FT‐IR) spectroscopy, circular dichroism (CD) and FT‐Raman spectroscopy were employed to analyze the binding of the asiatic acid (AA) to bovine serum albumin (BSA) under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by AA was the result of the formation of BSA‐AA complex. The fluorescence quenching mechanism of BSA by AA was a static quenching procedure. According to the Van′t Hoff equation, the thermodynamic parameters enthalpy change (ΔH0) and entropy change (ΔS0) for the reaction were evaluated to be ?12.55 kJ·mol?1 and 67.08 kJ·mol?1, respectively, indicating that hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The influence of AA on the conformation of BSA has also been analyzed on the basis of FT‐IR, CD and FT‐Raman spectra. 相似文献
984.
The unfolding of bovine heart cytochrome c induced by urea and guanidine hydrochloride was studied through their intrinsic fluorescence emission spectra, fluorescence phase diagrams, fluorescence quenching, size‐exclusion chromatographies, native polyacrylamide gel electrophoreses and deactivation profiles. The results showed that during their unfolding in urea and guanidine hydrochloride solutions, bovine heart cytochrome c molecules existed only in a unimolecular form and their bi‐molecular and/or poly‐molecular aggregates and aggregate precipitates were not formed all along. When the urea and guanidine hydrochloride concentrations in denaturation solution were separately about 6.0 and 3.0 mol/L, they could be completely deactivated and almost all of the tryptophan residues originally embedded in the interior of their molecules were exposed to the surface of their molecules. Different from the unfolding of the most often used horse heart cytochrome c, that of bovine heart cytochrome c induced by urea and guanidine hydrochloride was separately a completely co‐operative procedure and followed a two‐state model. 相似文献
985.
Shin Ichi Kuroda 《中国化学快报》2011,22(12):1505-1508
A series of poly(2-acetoxyethyl methacrylate)/polystyrene(PAEMA/PS) latex interpenetrating polymer networks(LIPNs) were prepared by seeded soap-free emulsion polymerization of styrene on the crosslinked PAEMA seed particles using an oil-soluble initiator.These PAEMA/PS LIPNs showed a well-defined phase-separated structure with PS phase dispersing in continuous PAEMA phase.The domain size of PS phase was found to depend on the crosslinking degree of PAEMA seed particles and the amount of second-stage styrene monomer. 相似文献
986.
Choi JJ Bealing CR Bian K Hughes KJ Zhang W Smilgies DM Hennig RG Engstrom JR Hanrath T 《Journal of the American Chemical Society》2011,133(9):3131-3138
The assembly of colloidal nanocrystals (NCs) into superstructures with long-range translational and orientational order is sensitive to the molecular interactions between ligands bound to the NC surface. We illustrate how ligand coverage on colloidal PbS NCs can be exploited as a tunable parameter to direct the self-assembly of superlattices with predefined symmetry. We show that PbS NCs with dense ligand coverage assemble into face-centered cubic (fcc) superlattices whereas NCs with sparse ligand coverage assemble into body-centered cubic (bcc) superlattices which also exhibit orientational ordering of NCs in their lattice sites. Surface chemistry characterization combined with density functional theory calculations suggest that the loss of ligands occurs preferentially on {100} than on reconstructed {111} NC facets. The resulting anisotropic ligand distribution amplifies the role of NC shape in the assembly and leads to the formation of superlattices with translational and orientational order. 相似文献
987.
A series of four novel 8-hydroxyquinoline-substituted boron-dipyrromethene derivatives, namely 4,4-difluoro-8-(5-(8-hydroxyquinoline))-3,5-dimethyl-4-bora-3a,4a-diaza-s-indacene (1), 4,4-difluoro-8-(5-(8-hydroxyquinoline))-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (2), 4,4-difluoro-8-(5-azastyryl-(8-hydroxyquinoline))-3,5-dimethyl-4-bora-3a,4a-diaza-s-indacene (3), and 4,4-difluoro-8-(5-azastyryl-(8-hydroxyquinoline))-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (4), have been synthesized and characterized by a series of spectroscopic methods. The molecular structures of 1 and 2 have been determined by single-crystal X-ray diffraction analyses. The two methyl substituents attached at C-1 and C-7 positions of boron-dipyrromethene (Bodipy) in compound 2 was revealed to prevent the free rotation of the 8-hydroxyquinoline (8-HQ) moiety, resulting in an almost vertical 8-HQ-Bodipy configuration of this compound. This is obviously different from those for 1 with the dihedral angle between 8-hydroxyquinoline and Bodipy moieties of 65.44 and 66.79° due to the lack of methyl substituents in the latter compound. The intense fluorescence from the Bodipy subunit of these compounds was revealed to gradually get diminished along with either decreasing or increasing the pH value under acidic and basic conditions, respectively, in particular for 1, 2, and 4 because of the photoinduced intramolecular electron transfer from excited Bodipy moiety to 8-HQ unit and just an opposite process. This renders these compounds the first OFF-ON-OFF type of pH-dependent fluorescent sensors. Nevertheless, both the intrinsic fluorescence of these compounds and their fluorescent quenching properties along with the change in the pH value have been found to depend on the steric configuration as well as the linking group between 8-hydroxyquinoline and Bodipy moieties, revealing the effect of molecular structure on their fluorescence properties. 相似文献
988.
989.
GY Zhu BC Wong A Lu ZX Bian G Zhang HB Chen YF Wong WF Fong Z Yang 《Chemical & pharmaceutical bulletin》2012,60(8):1029-1036
From the roots of Ardisia brevicaulis DIELS, two new alkylphenol derivatives, named ardisiphenol E (2) and F (3), have been isolated together with a known alkylphenol, ardisiphenol D (1). The structures of 1-3 were elucidated by chemical and spectroscopic techniques. Compounds 1 and 2 exhibited strong cytotoxicities on two human non-small-cell lung cancer cell lines (H1299 and A549). We found that compounds 1 and 2 upregulated mRNA and protein expressions of endoplasmic reticulum (ER) stress markers including C/EBP homologous protein (CHOP), binding immunoglobulin protein (Bip) and inositol-requiring enzyme 1 (IRE1) indicating 1 and 2 are novel natural ER stress inducers. Treatments with 1 and 5?μM of 1 or 2 triggered G1 arrest in H1299 and A549 cells with concomitant downregulation of ubiquitin fusion degradation protein 1 (Ufd1) and S-phase kinase-associated protein 2 (Skp2) proteins and the accumulation of p27, the key axes of ER stress-mediated G1 arrest. Compounds 1 and 2 also induced apoptosis at high concentrations (10, 20?μM) which was shown to be coupled with the upregulation of CHOP and Bim, the activation of caspase-9, caspase-3 and poly(ADP-ribose) polymerase (PARP) cleavage. These results indicate that compounds 1 and 2 induce ER stress that subsequently causes G1 arrest and apoptosis in human non-small-cell lung cancer cells and they may have potential anticancer effects. 相似文献
990.
Thiogermanates, {[Ni(phen)(3)](2)Ge(4)S(10)}·xSol (Sol = 4MeOH·12H(2)O (1) and 24H(2)O (2)) were prepared and characterized by single-crystal structure analysis. There are large quantities of the solvent molecules that cocrystallize with the anions and cations and form a strong hydrogen bonding network (O-H···S and O···H-O-H···O). Reversible yellow-pink color change with fast speed was found for these compounds, when the crystals were immersed in alcohol solvents and water alternately. The time of the solvent-induced color change relates to the molecular size and structure of the alcohols. The smaller the molecule is, the faster the color change will be. The fastest color change was found by using the methanol solvent that took only about one second. The color change also relates to the ratio of water/alcohol. The solvatochromism phenomenon is accompanied with a rapid solvent-induced recrystallization that is verified by the XRD patterns. 相似文献