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991.
Oskar?NuykenEmail author Steffen?Jungermann Valerie?Wiederhirn Erwin?Bacher Klaus?Meerholz 《Monatshefte für Chemie / Chemical Monthly》2006,137(7):811-824
Summary. Synthesis of crosslinkable small and large organic molecules having OLED properties will be presented. Three strategies for
the construction of multilayer devices will be described. In the first case small, well-defined OLED-molecules are functionalized
with oxetanes as crosslinker. The second case deals with polymers having OLED active units in the main chain and pendant crosslinkers
and finally it was shown that styrene polymers with pendant OLED functions and crosslinkers can be applied for the construction
of such multilayer and multicolour devices. 相似文献
992.
Han X Balakrishnan VK VanLoon GW Buncel E 《Langmuir : the ACS journal of surfaces and colloids》2006,22(21):9009-9017
The reaction of fenitrothion with a series of alpha-nucleophile oximates having pK(a) values in the range of 7.7-11.8 was studied both in the absence and presence of cetyltrimethylammonium (CTA(+)) surfactants. Reaction with CTA-oximates was found to proceed through two pathways: S(N)2(P) and S(N)2(C); an S(N)Ar pathway was not observed. Accordingly, the observed rate constants were dissected into the two corresponding S(N)2(P) and S(N)2(C) pathways. Use of the pseudophase ion exchange (PPIE) model for micellar catalysis in the CTA(+) system allowed evaluation of micellar second-order rate constant (k(2m)) parameters and binding constants, (K(S)). K(S) values for CTA-oximates were found to vary with the counterion, and the rate enhancement depended on a combination of K(S) and k(2m) values. k(2m)/k(2w) values ranged from 0.0025 to 0.64, suggesting that a concentration effect is mainly responsible for the rate enhancement. In the absence of surfactant, an alpha-effect (i.e., k(alpha)/k(normal)) varying from 8 to 450 was observed for the oximate reaction, decreasing with increasing pK(a). It is proposed that differential solvation (transition-state imbalance) is a cause of the alpha-effect in this system. 相似文献
993.
Salzmann CG Hallbrucker A Finney JL Mayer E 《Physical chemistry chemical physics : PCCP》2006,8(26):3088-3093
Raman spectra of recovered ordered H(2)O (D(2)O) ice XIII doped with 0.01 M HCl (DCl) recorded in vacuo at 80 K are reported in the range 3600-200 cm(-1). The bands are assigned to the various types of modes on the basis of isotope ratios. On thermal cycling between 80 and 120 K, the reversible phase transition to disordered ice V is observed. The remarkable effect of HCl (DCl) on orientational ordering in ice V and its phase transition to ordered ice XIII, first reported in a powder neutron diffraction study of DCl doped D(2)O ice V (C. G. Salzmann, P. G. Radaelli, A. Hallbrucker, E. Mayer, J. L. Finney, Science, 2006, 311, 1758), is demonstrated by Raman spectroscopy and discussed. The dopants KOH and HF have only a minor effect on hydrogen ordering in ice V, as shown by the Raman spectra. 相似文献
994.
Schmittel M Lin HW Thiel E Meixner AJ Ammon H 《Dalton transactions (Cambridge, England : 2003)》2006,(33):4020-4028
Homoleptic and heteroleptic ruthenium trisphenanthrolines were prepared with azacrown ethers attached to the 4,7-positions of the phenanthrolines to maximise the electronic communication between the ruthenium and the crown ethers as complexation sites. Redox and spectral data were processed to explain the non-steady trends in the absorption and emission spectra in the series. Addition of Ba2+ entailed large shifts in the redox potential (up to 370 mV) and in the emission spectra (up to 87 nm). Due to the crowded situation of the azacrown ether units in, this complex showed a non-linear behaviour both in the redox and emission properties upon loading with Ba2+ that is postulated to originate from the intermediate formation of sandwich type complexes. 相似文献
995.
Tuytten R Lemière F Esmans EL Herrebout WA van der Veken BJ Dudley E Newton RP Witters E 《Journal of the American Society for Mass Spectrometry》2006,17(8):1050-1062
In-source collision induced dissociation was applied to access second generation ions of protonated guanosine. The in-source gas-phase behavior of [BH2]+-NH3 (m/z 135, C5H3N4O+) was investigated. Adduct formation and reactions with available solvent molecules (H2O and CH3OH) were demonstrated. Several addition/elimination sequences were observed for this particular ion and solvent molecules. Dissociation pathways for the newly formed ions were developed using a QqTOF mass spectrometer, permitting the assignment of elemental compositions of all product ions produced. Reaction schemes were suggested arising from the ring-opened intermediate of the protonated base moiety [BH2]+, obtained from fragmentation of guanosine. The mass spectral data revealed that the in-source CH3OH-reaction product underwent more complex fragmentations than the comparable ion following reaction with H2O. A rearrangement and a parallel radical dissociation pathway were discerned. Apart from the mass spectrometric evidence, the fragmentation schemes are supported by density functional theory calculations, in which the reaction of the ring-opened protonated guanine intermediate with CH3OH and a number of subsequent fragmentations were elaborated. Additionally, an in-source transition from the ring-opened intermediate of protonated guanine to the ring-opened intermediate of protonated xanthine was suggested. For comparison, a low-energy collision induced dissociation study of xanthosine was performed. Its dissociation pathways agreed with our assumption. 相似文献
996.
Hyphenation of infrared spectroscopy (IR) to liquid chromatography (LC) has been applied to study chemical changes in poly(bisphenol A)carbonate (PC) as a result of degradation. Especially coupling of LC to FTIR through solvent elimination is a sensitive approach to identify changes in functionality observed in the LC chromatograms as has been demonstrated by coupling of liquid chromatography under critical conditions (LCCC) to IR. Furthermore, an example is shown in which two-dimensional liquid chromatography, i.e. LCCCxSEC, was coupled to IR by means of a flow cell. This resulted in data sets containing most probably valuable data, but extracting relevant information from these large data sets is not straightforward at all. Therefore, multivariate data analysis (MVDA) of SEC-FTIR data was used to extract relevant data from large data sets. This approach revealed chemical differences due to degradation that could not be detected by other means. Spectral features could be identified that allowed to quantitatively predict the degradation of poly(bisphenol A)carbonate as a function of degradation conditions. 相似文献
997.
Li B Adams E Van Schepdael A Hoogmartens J 《Rapid communications in mass spectrometry : RCM》2006,20(3):393-402
Six unknown compounds present in bulk gentamicin samples have been identified by ion-pairing reversed-phase liquid chromatography coupled with ion trap mass spectrometry. The structures of these unknown compounds were deduced by comparison of their fragmentation patterns with those of the available related substances and gentamicin reference substances. Seven other unknown components were partially identified. 相似文献
998.
Erwin Tegtmeier 《Metaphysica》2009,10(2):185-198
The three alternative ontological theories of time are introduced as well as the three basic temporal phenomena. The different ontological analyses by the different theories are compared and examined. A relational theory of time is advocated as a result of the examination, and an influential misrepresentation and emendation of it by McTaggart is criticized and diagnosed as hyperdynamism. Finally, the problem of the direction of time is addressed. The physicist’s solutions are rejected, and an ontological solution is offered. 相似文献
999.
Let G be a graph and S⊆V(G). For each vertex u∈S and for each v∈V(G)−S, we define to be the length of a shortest path in 〈V(G)−(S−{u})〉 if such a path exists, and ∞ otherwise. Let v∈V(G). We define if v⁄∈S, and wS(v)=2 if v∈S. If, for each v∈V(G), we have wS(v)≥1, then S is an exponential dominating set. The smallest cardinality of an exponential dominating set is the exponential domination number, γe(G). In this paper, we prove: (i) that if G is a connected graph of diameter d, then γe(G)≥(d+2)/4, and, (ii) that if G is a connected graph of order n, then . 相似文献
1000.
Computational analyses of mammalian lactate dehydrogenases: Human, mouse, opossum and platypus LDHs 总被引:1,自引:0,他引:1
Computational methods were used to predict the amino acid sequences and gene locations for mammalian lactate dehydrogenase (LDH) genes and proteins using genome sequence databanks. Human LDHA, LDHC and LDH6A genes were located in tandem on chromosome 11, while LDH6B and LDH6C genes were on chromosomes 15 and 12, respectively. Opossum LDHC and LDH6B genes were located in tandem with the opossum LDHA gene on chromosome 5 and contained 7 (LDHA and LDHC) or 8 (LDH6B) exons. An amino acid sequence prediction for the opossum LDH6B subunit gave an extended N-terminal sequence, similar to the human and mouse LDH6B sequences, which may support the export of this enzyme into mitochondria. The platypus genome contained at least 3 LDH genes encoding LDHA, LDHB and LDH6B subunits. Phylogenetic studies and sequence analyses indicated that LDHA, LDHB and LDH6B genes are present in all mammalian genomes examined, including a monotreme species (platypus), whereas the LDHC gene may have arisen more recently in marsupial mammals. 相似文献