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261.
We consider solutions ψ to equations of the form
in a sector Ω ofR
2. The basic assumptions are that the limitsa
ij(x)→δij,b
i(x)→0,c
i→E at infinity are achieved at certain rates and thatg decays faster than ψ. We then discuss the possible patterns of exponential decay for ψ in Ω.
NSERC University Research Fellow.
Research partially supported by USNEF grant MCS-83-01159. 相似文献
262.
263.
Synthesis,Characterization, and Theoretical Investigation of Two‐Coordinate Palladium(0) and Platinum(0) Complexes Utilizing π‐Accepting Carbenes 下载免费PDF全文
Dr. Sudipta Roy Dr. Kartik Chandra Mondal Dipl.‐Chem. Jann Meyer Dipl.‐Chem. Benedikt Niepötter Christian Köhler Dr. Regine Herbst‐Irmer Prof. Dr. Dietmar Stalke Dr. Birger Dittrich Dr. Diego M. Andrada Prof. Dr. Gernot Frenking Prof. Dr. Herbert W. Roesky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9312-9318
An elegant general synthesis route for the preparation of two coordinate palladium(0) and platinum(0) complexes was developed by reacting commercially available tetrakis(triphenylphosphine)palladium/platinum with π‐accepting cyclic alkyl(amino) carbenes (cAACs). The complexes are characterized by NMR spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction. The palladium complexes exhibit sharp color changes (crystallochromism) from dark maroon to bright green if the C‐Pd‐C bond angle is sharpened by approximately 6°, which is chemically feasible by elimination of one lattice THF solvent molecule. The analogous dark orange‐colored platinum complexes are more rigid and thus do not show this phenomenon. Additionally, [(cAAC)2Pd/Pt] complexes can be quasi‐reversibly oxidized to their corresponding [(cAAC)2Pd/Pt]+ cations, as evidenced by cyclic voltammetry measurements. The bonding and stability are studied by theoretical calculations. 相似文献
264.
Microstructure models at the grain size level open new potentials for the numerical investigation of micromechanical damage and fracturing. This paper presents a strategy to model heterogeneous brittle structures composed of binder and aggregate using the Discrete Element Method (DEM). A discretisation concept for both components was developed and implemented using spherical particles as discrete elements. The aggregate grains were modelled by clusters of these particles. Special routines were developed to generate specimens, to simulate laboratory tests and to analyse these simulations. Methods were developed to calibrate homogeneous and heterogeneous material by the determination of appropriate constitutive laws and their corresponding parameters. The simulation strategy allows to distinguish in detail between inter- and intra-granular microfracturing, between shear- and tensile-cracking and between microcracks within or between the different components of the heterogeneous material. Exemplarily, selected simulation results are presented for MgO-concrete. 相似文献
265.
Douradinha B van Dijk M van Gemert GJ Khan SM Janse CJ Waters AP Sauerwein RW Luty AJ Silva-Santos B Mota MM Epiphanio S 《Journal of immune based therapies and vaccines》2011,9(1):6-5
Background
The induction of sterile immunity and long lasting protection against malaria has been effectively achieved by immunization with sporozoites attenuated by gamma-irradiation or through deletion of genes. For mice immunized with radiation attenuated sporozoites (RAS) it has been shown that intrahepatic effector memory CD8+ T cells are critical for protection. Recent studies have shown that immunization with genetically attenuated parasites (GAP) in mice is also conferred by liver effector memory CD8+ T cells.Findings
In this study we analysed effector memory cell responses after immunization of GAP that lack the P52 protein. We demonstrate that immunization with p52 -GAP sporozoites also results in a strong increase of effector memory CD8+ T cells, even 6 months after immunization, whereas no specific CD4+ effector T cells response could be detected. In addition, we show that the increase of effector memory CD8+ T cells is specific for the liver and not for the spleen or lymph nodes.Conclusions
These results indicate that immunization of mice with P. berghei p52 -GAP results in immune responses that are comparable to those induced by RAS or GAP lacking expression of UIS3 or UIS4, with an important role implicated for intrahepatic effector memory CD8+ T cells. The knowledge of the mediators of protective immunity after immunization with different GAP is important for the further development of vaccines consisting of genetically attenuated sporozoites. 相似文献266.
da Silva AR Herbst MH Ferreira AB da Silva AM Visentin LC 《Molecules (Basel, Switzerland)》2011,16(2):1192-1200
The compound (10E)-2,2-dimethyl-3,4-dihydro-2H-benzo[g]chromene-5,10-dione-10-oxime (1) was synthesized from a-lapachone and hydroxylamine chloride in alkaline medium. Single-crystals suitable for X-ray diffraction measurements were grown from an ethanol solution, and the crystal structure of the title molecule is reported for the first time. The title molecule was also characterized by 1H- and 13C-NMR in CDCl? solution, FTIR and MS. The crystal structure of 1 shows an E stereochemistry and dimers formed through classical hydrogen bonds. 相似文献
267.
We prove that the Hamiltonian of the model describing a spin which is linearly coupled to a field of relativistic and massless
bosons, also known as the spin-boson model, admits a ground state for small values of the coupling constant λ. We show that
the ground-state energy is an analytic function of λ and that the corresponding ground state can also be chosen to be an analytic
function of λ. No infrared regularization is imposed. Our proof is based on a modified version of the BFS operator theoretic
renormalization analysis. Moreover, using a positivity argument we prove that the ground state of the spin-boson model is
unique. We show that the expansion coefficients of the ground state and the ground-state energy can be calculated using regular
analytic perturbation theory. 相似文献
268.
Sabine Herbst Nana Masada Sabrina Pfennig Christian H. Ihling Dermot M. F. Cooper Andrea Sinz 《Analytical and bioanalytical chemistry》2013,405(29):9333-9342
Calmodulin (CaM) is a highly conserved intracellular Ca2+-binding protein that exerts important functions in many cellular processes. Prominent examples of CaM-regulated proteins are adenylyl cyclases (ACs), which synthesize cAMP as a central second messenger. The interaction of ACs with CaM represents the link between Ca2+-signaling and cAMP-signaling pathways. Thereby, different AC isoforms stimulated by CaM, comprise diverse mechanisms of regulation by the Ca2+ sensor. To extend the structural information about the detailed mechanisms underlying the regulation of AC8 by CaM, we employed an integrated approach combining chemical cross-linking and mass spectrometry with two peptides representing the CaM-binding regions of AC8. These experiments reveal that the structures of CaM/AC8 peptide complexes are similar to that of the CaM/skeletal muscle myosin light chain kinase peptide complex where CaM is collapsed around the target peptide that binds to CaM in an antiparallel orientation. Cross-linking experiments were complemented by investigating the binding of AC8 peptides to CaM thermodynamically with isothermal titration calorimetry. There were no hints on a complex, in which both AC8 peptides bind simultaneously to CaM, refining our current understanding of the interaction between CaM and AC8. Figure
The interactions between calmodulin and two peptides, derived from the N- and C-termini of adenylyl cyclase 8, were analyzed by chemical cross-linking and mass spectrometry 相似文献
269.
Antonio C. A. da Costa Nazareth F. da Fonseca Sheyla S. de Carvalho Fernanda C. S. C. dos Santos Luana Barki Denise S. de Freitas Marcelo H. Herbst Márcia T. S. Lutterbach 《Central European Journal of Chemistry》2013,11(11):1729-1739
This paper investigates the behavior of paper strips containing iron-gall inks prepared with tannins from different sources, subjected to natural and thermally-induced aging. Results indicate that inks containing initial concentrations of ferrous sulphate ranging from 0.2 to 10.0 g are amenable to treatment with calcium phytate, and thata good correlation exists between the recovery of excess iron and the initial concentration. Infrared spectra showed an absorption band at 1,750 cm?1, typical of esther, solely in the samples prepared with a condensed tannin. The condensed nature of this tannin produced a different oxidation pattern, with iron removal inferior to those observed from inks produced with hydrolisable tannins. When tannic acid was used ferrous iron removals ranged from 0.050 to 1.800 g, decreasing to 0.5 g in the presence of copper; the same behavior was observed for the remaining hydrolisable tannins, with a lower recovery from the condensed tannin. The adopted natural aging procedure released a higher amount of ferrous iron compared to ASTM thermal aging. This was probably due to the marked effect of humidity, not considered in the thermal procedure. A series of archaeometric possibilities were used to help elucidate the degradation of cellulose strips impregnated with iron-gall inks. 相似文献
270.
Benedikt Niepötter Dr. Regine Herbst‐Irmer Dr. Daniel Kratzert Dr. Prinson P. Samuel Dr. Kartik Chandra Mondal Prof. Dr. Herbert W. Roesky Paul Jerabek Prof. Dr. Gernot Frenking Prof. Dr. Dietmar Stalke 《Angewandte Chemie (International ed. in English)》2014,53(10):2766-2770
An experimental and theoretical charge density study confirms the interpretation of (cAAC)2Si as a silylone to be valid. Two separated VSCCs present in the non‐bonding region of the central silicon are indicative for two lone pairs. In the experiment, both the two crystallographically independent Si? C bond lengths and ellipticities vary notably. It is only the cyclohexyl derivative that shows significant differences in these values, both in the silylones and the germylones. Only by calculating increasing spheres of surrounding point charges we were able to recover the changes in the properties of the charge density distribution caused by weak intermolecular interactions. The nitrogen–carbene‐carbon bond seems to have a significant double‐bond character, indicating a singlet state for the carbene carbon, which is needed for donor acceptor bonding. Thus the sum of bond angles at the nitrogen atoms seems to be a reasonable estimate for singlet versus triplet state of cAACs. 相似文献