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991.
Hoffmann R Obloh H Tokuda N Yang N Nebel CE 《Langmuir : the ACS journal of surfaces and colloids》2012,28(1):47-50
The crystalline form of sp(3)-hybridized carbon, diamond, offers various electrolyte-stable surface terminations. The H-termination-selective attachment of nitrophenyl diazonium, imaged by AFM, shows that electrochemical oxidation can control the fractional hydrogen/oxygen surface termination of diamond on the nanometer scale. This is of particular interest for all applications relying on interfacial electrochemistry, especially for biointerfaces. 相似文献
992.
Sound speeds have been measured for aqueous solutions of five tetrapeptides and five pentapeptides at T=298.15 K. The partial molar isentropic compressions at infinite dilution, $K_{S,2}^{\circ}$ , were derived for the peptides using conventional methods. The results were compared with those calculated using group additivity methods, with the amino acid side-chain contributions derived using $K_{S,2}^{\circ}$ data reported previously for some tripeptides of sequence gly-X-gly, where X represents an amino acid, and also for some N-acetyl amino acid amides. The tripeptides are the preferred model compounds for the estimation of the side-chain contributions to $K_{S,2}^{\circ}$ of a polypeptide. Our study also confirms that simple group additivity schemes are not feasible for the estimation of $K_{S,2}^{\circ}$ values for polypeptides and unfolded proteins. 相似文献
993.
Samples of a poly(ethylene oxide) trisiloxane surfactant, water, and decane have been investigated using pulsed field gradient
NMR (PGSE NMR) and small-angle neutron scattering (SANS) to determine the solution structure. The surfactant/water weight
ratio has been kept constant at a value of 3/2, with variation of the oil (decane) content. In the neutron scattering measurements
the temperature was varied from 23 °C up to the phase separation limit for these systems. The combined NMR and SANS data show
that on addition of decane, the system exists as a hexagonal phase of cylindrical decane-containing micelles at all temperatures
investigated. The addition of decane changes significantly the values for the structure parameters in the system, inducing
an increase in periodicity of 12–15 ?. By substitution of decane with its deuterated equivalent, decane-d22, it was possible to obtain detailed information on the structural organization of the oil component in this ternary mixture. 相似文献
994.
GA Senchyk VO Bukhan'ko AB Lysenko H Krautscheid EB Rusanov AN Chernega M Karbowiak KV Domasevitch 《Inorganic chemistry》2012,51(15):8025-8033
A series of new silver(I)-containing MOFs [Ag(2)(tr(2)ad)(2)](ClO(4))(2) (1), [Ag(2)(VO(2)F(2))(2)(tr(2)ad)(2)]·H(2)O (2), [Ag(2)(VO(2)F(2))(2)(tr(2)eth)(2)(H(2)O)(2)] (3), and [Ag(2)(VO(2)F(2))(2)(tr(2)cy)(2)]·4H(2)O (4) supported by 4-substituted bifunctional 1,2,4-triazole ligands (tr(2)ad = 1,3-bis(1,2,4-triazol-4-yl)adamantane, tr(2)eth = 1,2-bis(1,2,4-triazol-4-yl)ethane, tr(2)cy = trans-1,4-bis(1,2,4-triazol-4-yl)cyclohexane) were hydrothermally synthesized and structurally characterized. In these complexes, the triazole heterocycle as an N(1),N(2)-bridge links either two adjacent Ag-Ag or Ag-V centers at short distances forming polynuclear clusters. The crystal structure of compound 1 is based on cationic {Ag(2)(tr)(4)}(2+) fragments connected in a 2D rhombohedral grid network with (4,4) topology. The neighboring layers are tightly packed into a 3D array by means of argentophilic interactions (Ag···Ag 3.28 ?). Bridging between different metal atoms through the triazole groups assists formation of heterobimetallic Ag(I)/V(V) secondary building blocks in a linear V-Ag-Ag-V sequence that is observed in complexes 2-4. These unprecedented tetranuclear {Ag(2)(VO(2)F(2))(2)(tr)(4)} units (the intermetal Ag-Ag and Ag-V distances are 4.24-4.36 and 3.74-3.81 ?, respectively), in which vanadium(V) oxofluoride units possess distorted trigonal bipyramidal environment {VO(2)F(2)N}ˉ, are incorporated into 1D ribbon (2) or 2D square nets (3, 4) using bitopic μ(4)-triazole ligands. The valence bond calculation for vanadium atoms shows +V oxidation state in the corresponding compounds. Thermal stability and photoluminescence properties were studied for all reported coordination polymers. 相似文献
995.
Berillo D Mattiasson B Galaev IY Kirsebom H 《Journal of colloid and interface science》2012,368(1):226-230
In this study, it was found that macroporous hydrogels were formed when self-assembly of fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Phe-Phe) peptides was induced using glucono-δ-lactone (GdL) in apparently frozen samples. Formed cryogels exhibited a heterogeneous structure with pore walls of densely packed fibres of assembled dipeptides and pores in the range 10-100 μm. Hydrogels formed from the same composition above the freezing point exhibited a homogenous structure without any apparent porosity. The formed gels were characterised using microscopy techniques, CD-spectroscopy and stress sweeps. The cryogels exhibited less mechanical strength than the hydrogels that might be due to the heterogeneous structure of the former. It appeared that the self-assembled peptide both in the cryo- and hydrogel maintained the β-sheet structure commonly attributed to these. 相似文献
996.
Sengupta S Ebeling D Patwardhan S Zhang X von Berlepsch H Böttcher C Stepanenko V Uemura S Hentschel C Fuchs H Grozema FC Siebbeles LD Holzwarth AR Chi L Würthner F 《Angewandte Chemie (International ed. in English)》2012,51(26):6378-6382
Conductive tubes: Self-assembled nanotubes of a bacteriochlorophyll derivative are reminiscent of natural chlorosomal light-harvesting assemblies. After deposition on a substrate that consists of a non-conductive silicon oxide surface (see picture, brown) and contacting the chlorin nanowires to a conductive polymer (yellow), they show exceptional charge-transport properties. 相似文献
997.
J Prinz R Gaspari CA Pignedoli J Vogt P Gille M Armbrüster H Brune O Gröning D Passerone R Widmer 《Angewandte Chemie (International ed. in English)》2012,51(37):9339-9343
Scratching the surface: The high selectivity of PdGa catalysts towards the partial hydrogenation of acetylene was previously attributed to the separation of Pd atomic sites at the surfaces. The atomic structures of PdGa surfaces are determined by means of a combined experimental and computational approach, allowing investigation of the catalytic dissociation of hydrogen. The two opposite (111) and ${{\left( {\bar 1\bar 1\bar 1} \right)}}$ surfaces show a very different arrangement of catalytic centers. 相似文献
998.
999.
The electron ionization of helium droplets doped with methane clusters is investigated for the first time using high-resolution mass spectrometry. The dominant ion products ejected into the gas phase are the unprotonated (CH(4))(n)(+) cluster ions along with the protonated ions, CH(5)(+)(CH(4))(n-1). The mass spectra show clear evidence for magic numbers, which are broadly consistent with icosahedral shell closings. However, unusual features were observed, including different magic numbers for CH(5)(+)(CH(4))(n-1) (n=55, 148) when compared to (CH(4))(n)(+) (n=54, 147). Possible interpretations for some of these differences are proposed. Products of the type [C(2)H(x)(CH(4))(n)](+), which result from ion-molecule chemistry, are also observed and these too show clear magic number features. Finally, we report the first observation of (CH(4))(n)(2+) dications from methane clusters. The threshold for dication survival occurs at n≥70 and is in good agreement with a liquid droplet model for fission of multiply charged ions. Furthermore, we present evidence showing that these dications are formed by an unusual two-step mechanism which is initiated by charge transfer to generate a monocation and is then followed by Penning ionization to generate a dication. 相似文献
1000.
B Andreasen DM Tanenbaum M Hermenau E Voroshazi MT Lloyd Y Galagan B Zimmernann S Kudret W Maes L Lutsen D Vanderzande U Würfel R Andriessen R Rösch H Hoppe G Teran-Escobar M Lira-Cantu A Rivaton GY Uzunoğlu DS Germack M Hösel HF Dam M Jørgensen SA Gevorgyan MV Madsen E Bundgaard FC Krebs K Norrman 《Physical chemistry chemical physics : PCCP》2012,14(33):11780-11799
The present work is the fourth (and final) contribution to an inter-laboratory collaboration that was planned at the 3rd International Summit on Organic Photovoltaic Stability (ISOS-3). The collaboration involved six laboratories capable of producing seven distinct sets of OPV devices that were degraded under well-defined conditions in accordance with the ISOS-3 protocols. The degradation experiments lasted up to 1830 hours and involved more than 300 cells on more than 100 devices. The devices were analyzed and characterized at different points of their lifetimes by a large number of non-destructive and destructive techniques in order to identify specific degradation mechanisms responsible for the deterioration of the photovoltaic response. Work presented herein involves time-of-flight secondary ion mass spectrometry (TOF-SIMS) in order to study chemical degradation in-plane as well as in-depth in the organic solar cells. Various degradation mechanisms were investigated and correlated with cell performance. For example, photo-oxidation of the active material was quantitatively studied as a function of cell performance. The large variety of cell architectures used (some with and some without encapsulation) enabled valuable comparisons and important conclusions to be drawn on degradation behaviour. This comprehensive investigation of OPV stability has significantly advanced the understanding of degradation behaviour in OPV devices, which is an important step towards large scale application of organic solar cells. 相似文献