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201.
Zusammenfassung Im Anschluß an frühere Untersuchungen konnte aus einer Siedefraktion eines Schieferölraffinates nach Anwendung verschiedener chromatographischer Verfahren eine Reihe von Verbindungen isoliert und mit spektroskopischen Methoden charakterisiert werden.Die nachfolgende Aufzählung der Verbindungsklassen erfolgt in der Reihenfolge ihres mengenmäßigen Vorkommens: 2,2-Dithienyle, 2-Phenylthiophene, Thionaphthene, Thiophene, Dithienyl-methane,-äthane und-propane, Naphthaline, Benzole, Alkane, Alkene, Thiophthene, Diphenyle, Fluorene, tricyclische Aromaten, sowie tricyclische Schwefel-und Sauerstoffheteroaromaten. Die aromatischen Ringsysteme waren fast ausschließlich alkylsubstituiert.
Herrn Prof. Dr.K. Jentsch mit den besten Wünschen zum 60. Geburtstag gewidmet.
4. Mitt.:M. Pailer undH. Begutter 相似文献
Studies of shale oils with high sulphur content. 5
In continuation of earlier investigations, a series of compounds were isolated from a distillate fraction of a shale oil raffinate after the application of various chromatographic procedures, and characterized by spectroscopic methods.The following compound types are arranged in order of their abundance: 2,2-dithienyls, 2-phenylthiophenes, thionaphthenes, thiophenes, dithienylmethanes,-ethanes and-propanes, naphthalenes, benzenes, alkanes, alkenes, thiophthenes, diphenyls, fluorenes, tricyclic aromatics, tricyclic sulphur and oxygen heterocycles. The aromatic ring systems were almost invariably alkyl substituted.
Herrn Prof. Dr.K. Jentsch mit den besten Wünschen zum 60. Geburtstag gewidmet.
4. Mitt.:M. Pailer undH. Begutter 相似文献
202.
D. G. Middleton J. R. M. Annand C. Barbieri P. Barneo P. Bartsch D. Baumann J. Bermuth D. Bosnar H. P. Blok R. Böhm M. Ding M. O. Distler D. Elsner J. Friedrich C. Giusti D. I. Glazier P. Grabmayr S. Grözinger T. Hehl J. Heim W. H. A Hesselink E. Jans F. Klein M. Kohl L. Lapikás I. J. D. MacGregor I. Martin J. C. McGeorge H. Merkel P. Merle F. Moschini U. Müller Th. Pospischil G. Rosner H. Schmieden M. Seimetz A. Süle H. de Vries Th. Walcher D. P. Watts M. Weis B. Zihlmann 《The European Physical Journal A - Hadrons and Nuclei》2006,30(2):469-469
203.
Mahlert C Sieber SA Grünewald J Marahiel MA 《Journal of the American Chemical Society》2005,127(26):9571-9580
Streptogramin B antibiotics are cyclic peptide natural products produced by Streptomyces species.In combination with the synergistic group A component, they are "last line of defense" antimicrobial agents against multiresistant cocci. The racemization sensitivity of the phenylglycine (Phg(7)) ester is a complex challenge in total chemical synthesis of streptogramin B molecules. To provide fast and easy access to novel streptogramin antibiotics, we introduce a novel chemoenzymatic strategy in which diversity is generated by standard solid phase protocols and stereoselectivity by subsequent enzymatic cyclization. For this approach, we cloned, overproduced, and biochemically characterized the recombinant thioesterase domain SnbDE TE of the pristinamycin I nonribosomal peptide synthetase from Streptomyces pristinaespiralis. SnbDE TE catalyzes regioselective ring closure of linear peptide thioester analogues of pristinamycin I as well as stereoselective cyclization out of complex in situ racemizing substrate mixtures, enabling synthesis of Streptogramin B variants via a dynamic kinetic resolution assay. A remarkable substrate tolerance was detected for the enzymatic cyclization including all the seven positions of the peptide backbone. Interestingly, SnbDE TE was observed to be the first cyclase from a macrolactone forming NRPS which is additionally able to catalyze macrolactamization of peptide thioester substrates. An N-methylated peptide bond between positions 4 and 5 is mandatory for a high substrate turnover. The presented strategy is potent to screen for analogues with improved activity and guides our understanding of structure--activity relationships in the important class of streptogramin antibiotics. 相似文献
204.
205.
Energy and hole transfer between dyes attached to titania in cosensitized dye-sensitized solar cells
Hardin BE Sellinger A Moehl T Humphry-Baker R Moser JE Wang P Zakeeruddin SM Grätzel M McGehee MD 《Journal of the American Chemical Society》2011,133(27):10662-10667
Cosensitization of broadly absorbing ruthenium metal complex dyes with highly absorptive near-infrared (NIR) organic dyes is a clear pathway to increase near-infrared light harvesting in liquid-based dye-sensitized solar cells (DSCs). In cosensitized DSCs, dyes are intimately mixed, and intermolecular charge and energy transfer processes play an important role in device performance. Here, we demonstrate that an organic NIR dye incapable of hole regeneration is able to produce photocurrent via intermolecular energy transfer with an average excitation transfer efficiency of over 25% when cosensitized with a metal complex sensitizing dye (SD). We also show that intermolecular hole transfer from the SD to NIR dye is a competitive process with dye regeneration, reducing the internal quantum efficiency and the electron lifetime of the DSC. This work demonstrates the general feasibility of using energy transfer to boost light harvesting from 700 to 800 nm and also highlights a key challenge for developing highly efficient cosensitized dye-sensitized solar cells. 相似文献
206.
Gröger K Baretić D Piantanida I Marjanović M Kralj M Grabar M Tomić S Schmuck C 《Organic & biomolecular chemistry》2011,9(1):198-209
Two novel guanidiniocarbonyl pyrrole-pyrene conjugates 3 and 4 as spectroscopic probes for ds-polynucleotides were synthesized and their interaction with different ds-DNAs/RNAs studied. Compared to a previously reported first set of conjugates (1 and 2) the significant extension and increased rigidity of the central part of the structure resulted in a switch of DNA binding mode from intercalative (previously studied derivatives 1 and 2 with a nonbinding and flexible linker) to minor groove binding of the two novel guanidiniocarbonyl-pyrrole-pyrene conjugates 3 and 4. These two compounds interact strongly with ds-DNAs, but only weakly with ds-RNA. The newly incorporated heterocyclic moieties within the central part of the structure of 3 and 4 were able to control by steric and hydrogen-bonding effects the alignment of the molecules within various, structurally different forms of DNA minor grooves, whereby even small differences in the position of the attached pyrene within the groove were reflected in different fluorimetric responses. In addition, 3 and 4 revealed intriguing in vitro selectivity among various human tumour cell lines. 相似文献
207.
Jennings JR Liu Y Wang Q Zakeeruddin SM Grätzel M 《Physical chemistry chemical physics : PCCP》2011,13(14):6637-6648
Replacing the nonyl groups on the solar cell dye Ru(4,4'-carboxylic acid-2,2'-bipyridine)(4,4'-dinonyl-2,2'-bipyridine)(NCS)(2) (Z-907) with amino groups results in a marked decrease in solar cell performance. This is despite the fact that the amino derivative (Z-960) has more favourable light absorption characteristics than Z-907 when used with thick nanocrystalline TiO(2) layers. Electron transfer to the electrolyte from the exposed fluorine-doped tin oxide (FTO) substrate is particularly fast in cells employing the Z-960 dye if a compact TiO(2) blocking layer is not used. The kinetics of electron transfer from the nanocrystalline TiO(2) layer in DSCs employing Z-960 are comparable to those of bare TiO(2) and ca. 2 to 5 times faster than for cells employing Z-907. The faster charge recombination in cells employing Z-960 lowers open-circuit photovoltage and results in very significant charge collection losses that lower short-circuit photocurrent. Voltammetric measurements show that surface modification of FTO electrodes with Z-960 results in slightly more facile charge transfer to acceptor species in triiodide/iodide electrolytes in the dark. A simpler molecule, p-aminobenzoic acid, more dramatically catalyses this charge transfer reaction. Conversely, chemical modification of FTO electrodes with Z-907 or p-toluic acid retards charge transfer kinetics. Similar results are obtained for nanocrystalline TiO(2) electrodes modified with these benzoic acid derivatives. These results strongly imply that surface adsorbed molecules bearing amino groups, including dye molecules, can catalyse charge recombination in dye-sensitized solar cells. 相似文献
208.
Homoallylic substrates such as (E)-6-arylhex-3-enyl alcohols, N-tosylamides, and thiols undergo smooth cross-coupling with various aldehydes in the presence of 10 mol % Sc(OTf)(3) and 30 mol % TsOH to afford the trans-fused hexahydro-1H-benzo[f]isochromenes, N-tosyloctahydrobenzo[f]isoquinolines, and hexahydro-1H-benzo[f]isothiochromenes, respectively. However, the cross-coupling of (Z)-olefins such as 6-arylhex-3-enyl alcohols, N-tosylamides, and thiols with aldehydes affords the corresponding hexahydro-1H-benzo[f]isochromenes, N-tosyloctahydrobenzo[f]isoquinolines, and hexahydro-1H-benzo[f]isothiochromenes with complete cis selectivity via intramolecular Prins-, aza-Prins-, and thia-Prins/Friedel-Crafts cyclizations, respectively. Though the Prins cyclization proceeds smoothly under the influence of Sc(OTf)(3), high conversions and enhanced reaction rates are achieved using a mixture of Sc(OTf)(3) and TsOH (1:3). 相似文献
209.
Grünker R Senkovska I Biedermann R Klein N Lohe MR Müller P Kaskel S 《Chemical communications (Cambridge, England)》2011,47(1):490-492
A flexible Metal-Organic Framework Zn(4)O(BenzTB)(3/2) (DUT-13) was obtained by combination of a tetratopic linker and Zn(4)O(6+) as connector. The material has a corundum topology and shows the highest pore volume among flexible MOFs. 相似文献
210.
Padmanaban M Müller P Lieder C Gedrich K Grünker R Bon V Senkovska I Baumgärtner S Opelt S Paasch S Brunner E Glorius F Klemm E Kaskel S 《Chemical communications (Cambridge, England)》2011,47(44):12089-12091
A modular approach for the synthesis of highly ordered porous and chiral auxiliary (Evans auxiliary) decorated metal-organic frameworks is developed. Our synthesis strategy, which uses known porous structures as model materials for incorporation of chirality via linker modification, can provide access to a wide range of porous materials suitable for enantioselective separation and catalysis. Chiral analogues of UMCM-1 have been synthesized and investigated for the enantioseparation of chiral compounds in the liquid phase and first promising results are reported. 相似文献