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81.
Gregorio Sánchez David J Meseguer José Pérez Gregorio López 《Inorganica chimica acta》2004,357(3):677-683
The hydroxo complex [NBu4]2[Ni2(C6F5)4(μ-OH)2] reacts with ammonium O,O′-dialkyldithiophosphates, O-alkyl-p-methoxyphenyldithiophosphonate acids and ammonium O-alkylferrocenyldithiophosphonates in dichloromethane under mild conditions to give, respectively, [NBu4][Ni(C6F5)2{S(S)P(OR)2}] (R=Me (1), Et (2), iPr (3)) and [NBu4][Ni(C6F5)2{S(S)P(OR)Ar}] (Ar=p-MeOC6H4, R=Me (4), Et (5), iPr (6); Ar=ferrocenyl; R=Me (7), Et (8), iPr (9)). The monothiophosphonate nickel complexes [NBu4][Ni(C6F5)2{S(S)P(OR)(ferrocenyl)}] (R=Et (10), iPr (11)) are obtained by reaction of the hydroxo complex with O-alkylferrocenyldithiophosphonate acids. Analytical (C, H, N, S), conductivity, and spectroscopic (IR, 1H, 19F and 31P NMR, and FAB-MS) data were used for structural assignments. A single-crystal X-ray diffraction study of [NBu4][Ni(C6F5)2{S(S)P(OMe)(p-MeOC6H4)}] (4) and [NBu4][Ni(C6F5)2{S(O)P(OEt)(ferrocenyl)}] (10) shows that in both cases the coordination around the nickel atom es essentially square planar with NiC2S2 and NiC2SO central cores, respectively. 相似文献
82.
Bis(pyridine) complexes of molybdenum and tungsten, [M(η3-allyl)Cl(CO)2(NC5H5)2] (M=Mo; 3-Mo, M=W; 3-W), reacted with an equimolar amount of lithiated amidinate, Li[(PhN)2CR] (R=H; 4a-Li, R = CH3; 4b-Li), to yield corresponding amidinato(pyridine) complexes, [M(η3-allyl){(PhN)2CR}(CO)2(NC5H5)] (M=Mo, R=H; 5a-Mo, M=Mo, R=CH3; 5b-Mo, M=W, R=H; 5a-W), as a yellow solid. The dissociation of pyridine ligand from the central metal in complexes 5a was observed in a polar solvent such as acetonitrile. In these cases, although the formation of amidinato(acetonitrile) complexes, [M(η3-allyl){(PhN)2CH}(CO)2(NCMe)] (M=Mo; 6a-Mo, M=W; 6a-W), was suggested spectroscopically, isolation of complexes 6a was not successful but the re-formation of pyridine complexes 5a was observed. In the reactions of complexes 5a with PEt3 and with P(OMe)3, the substitution reactions easily took place to give [M(η3-allyl){(PhN)2CH}(CO)2(PEt3)] (M=Mo; 7a-Mo, M=W; 7a-W) and [M(η3-allyl){(PhN)2CH}(CO)2{P(OMe)3}] (M=Mo; 8a-Mo, M=W; 8a-W), respectively. These complexes were characterized spectroscopically as well as, in some cases, by X-ray analyses. 相似文献
83.
Pieter Steenhuis Stephanie Herder Suyin Gelis Thomas Braulke Stephan Storch 《Traffic (Copenhagen, Denmark)》2010,11(7):987-1000
CLN7 is a polytopic lysosomal membrane protein deficient in variant late infantile neuronal ceroid lipofuscinosis, a neurodegenerative lysosomal storage disorder. In this study fluorescence protease protection assays and mutational analyses revealed the N‐ and C‐terminal tails of CLN7 in the cytosol and two N‐glycosylation sites at N371 and N376. Both partially and non‐glycosylated CLN7 were correctly transported to lysosomes. To identify lysosomal targeting motifs, we generated CD4‐chimera fused to the N‐ and C‐terminal domains of CLN7. Lysosomal localization of the chimeric proteins requires a consensus acidic dileucine‐based motif in the N‐terminus and two tandem tyrosine‐based signals in the C‐terminus. Mutation of these sorting motifs resulted in cell surface redistribution of CD4 chimeras. However, the dileucine‐based motif is of critical importance for lysosomal localization of the full‐length CLN7 in different cell lines. Cell surface biotinylation revealed that at equilibrium 22% of total CLN7 is localized at the plasma membrane. Mutation of the dileucine motif or the co‐expression of dominant‐negative mutant dynamin K44A led to a further increase of CLN7 at the plasma membrane. Our data demonstrate that CLN7 contains several cytoplasmic lysosomal targeting signals of which the N‐terminal dileucine‐based motif is required for the predominant lysosomal targeting along the indirect pathway and clathrin‐mediated endocytosis of CLN7. 相似文献
84.
A series of cationic, half-sandwich ruthenium complexes with the general formula [(η6-p-cymene)RuCl(MeSC6H42-NCHAr)][PF6] (3a-h), have been prepared from the reaction of [(η6-p-cymene)RuCl2]2 with various N,S-donor Schiff base ligands derived from 2-(methylthio)aniline and several substituted benzaldehydes. The related aniline complex [(η6-p-cymene)RuCl(MeS-C6H4-2-NH2)][PF6] (4) was synthesized from 2-(methylthio)aniline. All of the ruthenium complexes were characterized by IR, 1H NMR, and UV/Vis spectroscopies. The molecular structure of complex 4 was determined by X-ray crystallography. 相似文献
85.
Normen Szesni 《Inorganica chimica acta》2006,359(2):617-632
Bis(alkoxy)allenylidene complexes, [(CO)5MCCC(OR′)OR], as well as mono(alkoxy)allenylidene complexes, [(CO)5MCCC(OR′)Ph], of chromium and tungsten are accessible from propynones [HCCC(O)Ph] or propynoic acid esters [HCCC(O)OR; R = Et, (−)-menthyl, endo-bornyl] by the following reaction sequence: (a) deprotonation of the alkynes, (b) reaction with [(CO)5M-THF] (M = Cr, W), and (c) alkylation of the resulting alkynyl metallate, [(CO)5MCCC(O)R], with Meerwein salts. Vinylidene complexes, [(CO)5MCC(R′)C(O)OR], are formed as a by-product by Cβ-alkylation of the alkynyl metallate. Dimethylamine displaces one alkoxy substituent of the bis(alkoxy)allenylidene complexes to give dimethylamino(alkoxy)allenylidene complexes, [(CO)5MCCC(OR)NMe2]. The analogous reaction of dimethylamine with a mono(alkoxy)-substituted allenylidene complex affords the aminoallenylidene complex [(CO)5CrCCC(NMe2)Ph]. When the amine is used in large excess, the α,β-unsaturated aminocarbene complex [(CO)5CrC(NMe2)C(H)C(NMe2)Ph] is additionally formed by addition of the amine across the CαCβ-bond of the allenylidene ligand. The reaction of [(CO)5MCCC(OEt)2] with dimethyl ethylenediamine offers access to bis(amino)allenylidene complexes, in which Cγ is part of a five-membered heterocycle. Photolysis of bis(alkoxy)allenylidene complexes in the presence of triphenylphosphine yields tetracarbonyl- and tricarbonyl{bis(phosphine)}allenylidene complexes. Diethylaminopropyne inserts into the CβCγ bond of [(CO)5MCCC(OEt)OMethyl] to give alkenylallenylidene complexes. Subsequent acid-catalyzed intramolecular cyclization affords a pyranylidene complex. 相似文献
86.
Etelka?Farkas Yiffat?Katz Sudhakar?Bhusare Reuven?Reich Gerd-Volker?R?schenthaler Martin?K?nigsmann Eli?BreuerEmail author 《Journal of biological inorganic chemistry》2004,9(3):307-315
Overactive matrix metalloproteinases (MMPs) are associated with a variety of disease states. Therefore, their inhibition is a highly desirable goal. Yet, more than a decade of worldwide activity has not produced even one clinically useful inhibitor. Because of the crucial role of zinc in the activity of the enzyme, the design of inhibitors is usually based upon a so-called zinc binding group (ZBG). Yet, many of the hitherto synthesized potent inhibitors failed clinically, presumably because they bind stronger to metals other than zinc. We have developed in vivo potent inhibitors based on the carbamoylphosphonic group as a putative ZBG. In this paper we report stability constants for Ca(II), Mg(II), Zn(II) and Cu(II) complexes of two potent, in vivo active, MMP inhibitors, cyclopentylcarbamoylphosphonic acid (1) and 2-(N,N-dimethylamino)ethylcarbamoylphosphonic acid (2). Precipitation prevented the determination of stability constants for iron(III) complexes of 1 and 2. For comparison with carbamoylphosphonates 1 and 2, we synthesized 2-cyclohexyl-1,1-difluoroethylphosphonic acid (3), which does not inhibit MMP, and determined the stability constants of its complexes with Mg(II), Ca(II) and Zn(II). Comparison with the values obtained from the complexes of 1 and 2 with those from 3 indicates participation of the C=O group in the metal binding of the former compounds. The complex stability orders for both 1 and 2 are Ca(II)<Mg(II)<Zn(II)<Cu(II). In addition, the results indicate that at pH>8 the dimethylamino group of compound 2 can also participate in the binding of the transition metals Cu and Zn. On the other hand, the amino group in carbamoylphosphonic acid 2 lowers the stability of the complexes with metals favoring oxygen ligands (Ca, Mg and Fe) and increases the selectivity towards Zn. These results are helpful for rationalizing the results observed on our MMP inhibitors hitherto examined, and are expected to be useful for the design of new selective inhibitors.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00775-004-0524-5 相似文献
87.
Robert C. Jennings Flavio M. Garlaschi Paolo D. Gerola Rachel Etzion-Katz Giorgio Forti 《BBA》1981,638(1):100-107
Lowering the pH of the incubation medium to pH 5.4 leads to grana formation morphologically similar to that induced by metal cations. The same phenomenon is observed in EDTA-washed chloroplasts, indicating that it is not due in part to electrostatic ‘masking’ by residual cations associated with the membranes. Digitonin fractionation studies have indicated that the distribution of the major chlorophyll-protein complexes between granal and stromal membrane regions is similar at pH 5.4 in the absence of Mg2+, and at pH 7.4 in the presence of Mg2+. Chlorophyll fluorescence induction studies have indicated that the primary photochemistry of Photosystem II (PS II) is stimulated by lowering the pH to 5.4, just as it is upon metal cation addition at higher pH values. The failure to observe such an increase at pH 5.4 by measuring electron transport to ferricyanide is attributed to a combination of an inhibition by this pH of electron transport at a site after Q reduction and an increase in the number of PS II centres detached from the plastoquinone pool. We conclude that the stacked configuration of chloroplast membranes leads to increased PS II primary photochemistry, which is most simply explained in terms of a redistribution of excitation energy towards PS II. 相似文献
88.
David A. Jacques Jill Trewhella 《Protein science : a publication of the Protein Society》2010,19(4):642-657
The last decade has seen a dramatic increase in the use of small‐angle scattering for the study of biological macromolecules in solution. The drive for more complete structural characterization of proteins and their interactions, coupled with the increasing availability of instrumentation and easy‐to‐use software for data analysis and interpretation, is expanding the utility of the technique beyond the domain of the biophysicist and into the realm of the protein scientist. However, the absence of publication standards and the ease with which 3D models can be calculated against the inherently 1D scattering data means that an understanding of sample quality, data quality, and modeling assumptions is essential to have confidence in the results. This review is intended to provide a road map through the small‐angle scattering experiment, while also providing a set of guidelines for the critical evaluation of scattering data. Examples of current best practice are given that also demonstrate the power of the technique to advance our understanding of protein structure and function. 相似文献
89.
Novel calix[4]pyrrole bearing vic-dioxime ligand (LH2) of the general formula, R1R2C2N2O2H2 (where, R1 = C6H5- and R2 = C39H50N5-) has been synthesized by the reaction of anti-chlorophenylglyoxime with 3-aminophenylcalix[4]pyrrole at room temperature. The mononuclear Cu(II), Ni(II) and Co(II)complexes of this vic-dioxime ligand were prepared and their structures were confirmed by elemental analysis, FT-IR, TGA and magnetic susceptibility measurements; the HMBC, DEPT, 1H and 13C NMR spectra of the LH2 ligand were also reported. The electrochemical property of the complexes was investigated in DMSO by cyclic voltammetry at 200 mV s−1 scan rate. The cyclic voltammetric measurements clearly indicated that Co(LH)2·2H2O complex differs from the Ni(LH)2 and Cu(LH)2 complexes upon the exhibition of quasi-reversible one-electron transfer reduction process in the negative region instead of an irreversible process. 相似文献
90.
Kaushik Ghosh Nidhi Tyagi Pramod Kumar Udai P. Singh Nidhi Goel 《Journal of inorganic biochemistry》2010,104(1):9-18
A new family of tridentate ligands PhimpH (2-((2-phenyl-2-(pyridin-2-yl)hydazono)methyl)phenol), N-PhimpH (2-((2-phenyl-2-(pyridin-2-yl)hydrazono)methyl)napthalen-1-ol), Me-PhimpH (2-(1-(2-phenyl-2-(pyridine-2-yl)hydrazono)ethyl)phenol) have been synthesized and characterized. The ligands PhimpH and N-PhimpH after deprotonation react with manganese(II) and manganese(III) starting materials affording [Mn(Phimp)2] (1), [Mn(Phimp)2](ClO4) (2), [Mn(N-Phimp)2] (3), [Mn(N-Phimp)2](ClO4) (4). Complexes [Mn(Phimp)2] (1) and [Mn(N-Phimp)2] (3) convert to [Mn(Phimp)2]+ (cation of 2) and [Mn(N-Phimp)2]+ (cation of 4) respectively upon oxidation. Ligand Me-PhimpH stabilized only manganese(III) centre resulting [Mn(Me-Phimp)2](ClO4) (5). The molecular structures of [Mn(Phimp)2], 1 and [Mn(Phimp)2](ClO4), 2 were determined by single crystal X-ray diffraction. X-ray crystal structures of 1 and 2 have revealed the presence of distorted octahedral MnN4O2 coordination sphere having meridionally spanning ligands. Electrochemical studies for the complexes showed Mn(II)/Mn(III), (E1/2 = 0.14-0.40 V) and Mn(III)/Mn(IV), (E1/2 = 0.80-1.06 V) couples vs. Ag/AgCl. The redox properties were exploited to examine superoxide dismutase (SOD) activity using Mn(II)/Mn(III) couple. The complexes 1, 2, 4 and 5 have been revealed to catalyze effectively the dismutation of superoxide () in xanthine-xanthine oxidase-nitro blue tetrazolium assay and IC50 values were found to be 0.29, 0.39, 1.12 and 0.76 μM respectively. DNA interaction studies with complex 2 showed binding of DNA in a non-intercalative pathway. Complexes 1, 2 and 4 exhibited nuclease activity in presence of H2O2 and inhibition of activity was noted in presence of KI. 相似文献