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901.
Light sensitivity and potential stability of electrically conducting polymers commonly used in solid contact ion-selective electrodes 总被引:1,自引:0,他引:1
Tom Lindfors 《Journal of Solid State Electrochemistry》2009,13(1):77-89
The results of a systematic study of the light sensitivity and long-term potential stability (30 days) of poly(pyrrole) (PPy),
poly(3-octylthiophene) (POT), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(aniline) (PANI) and plasticised poly(vinyl chloride)
(PVC) containing 20% (m/m) PANI are reported. Thin films were prepared either electrochemically or by the solution casting technique. This fundamental
study is of importance because conducting polymers (CP) are commonly used as ion-to-electron transduction materials in all-solid-state
solid contact ion-selective electrodes. The potential stability test done in 0.1 M KCl (pH 7.5) simulates the extreme situation
when the CP-based SC becomes in direct contact with water. Films prepared of a nanodispersion of PANI showed both good potential
stability and insensitivity to light even under illumination with very intensive light (>105 lx). In contrary, it was observed that POT is very light-sensitive. Upon illumination with intensive light, the potential
responses of POT films prepared by solution casting and electropolymerisation were 315 and 590 mV, respectively. A room light
sensitivity of approximately −10 to −15 mV was observed for these films. The other CPs in this study were insensitive to room
light (∼150 lx), but were light-sensitive under illumination with intensive light. The potential drift of PPy(Cl) is below
−10 μV/h (3–30 days), whereas the other most stable CPs in this study had a slightly higher potential drift. 相似文献
902.
Francoise Sauriol Dr. Elizabeth Wong Angela M. H. Leung Irja Elliott Donaghue Michael C. Baird Prof. Tebikie Wondimagegn Dr. Tom Ziegler Prof. 《Angewandte Chemie (International ed. in English)》2009,48(18):3342-3345
Caught in the act : An alkyl alkene ZrIV complex (see picture; Cp=C5H5) has been synthesized and characterized for the first time. The alkene bonding mode is highly asymmetric, and C2 is quite carbocationic. There is also evidence for rotation about the C1? C2 bond. This extremely unusual complex provides an exemplar of previously unknown intermediates in Ziegler–Natta and carbocationic polymerization reactions of alkenes.
903.
We prove that the semirings of 1-preserving and of 0,1-preserving endomorphisms of a semilattice are always subdirectly irreducible
and we investigate under which conditions they are simple. Subsemirings are also investigated in a similar way. 相似文献
904.
Triadic interactions have a very important role to play in games of animal conflict on complex networks, because triads are both the simplest groups in which asymmetric network phenomena can be studied and the groups beyond dyads in which analysis of population games is most likely to be tractable, especially when allowing for intrinsic variation. Here we demonstrate how analytical models of triadic games can yield novel insights into a variety of behavioral phenomena within networks, including coalition formation, eavesdropping, and victory displays. © 2008 Wiley Periodicals, Inc. Complexity, 2009 相似文献
905.
In order to gain deeper inside into the behavior of a Lorentz-force controlled flow behind a backward-facing step, measurements with a laser Doppler velocity profile sensor were undertaken. By varying the frequency of the sinusoidal Lorentz-force the influence on the turbulence statistics was studied. Moreover, phase resolved measurement data is presented. The results confirm the characteristic frequency determined on basis of the momentum thickness beforehand. The aim of this study is to understand the influence of the different incitation signals and to reduce the reattachment length. The statistical results show a dependency of the turbulence degree on the excitation frequency as well as a deformation of the flow profile behind the step. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
906.
Barluenga J García-Rodríguez J Martínez S Suárez-Sobrino AL Tomás M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(12):3201-3210
We examined the reactivity of dimethylaminodiazafulvene 1 toward Fischer alkenylcarbene 2 and alkynylcarbene 3 complexes. Diazafulvene 1 reacts with alkenylcarbenes 2 through a formal [6+3] heterocyclization in a regio- and stereoselective manner to afford dihydroimidazo[1,2-a]pyridines 4. Acid-promoted dimethylamine elimination in compound 4 c gives rise to the aromatic imidazo pyridine 5. A likely mechanism for this reaction is a 1,2-nucleophilic addition/[1,2]-shift metal-promoted cyclization sequence. On the other hand, diazafulvene 1 and alkynyl carbenes 3 undergo a [6+2] cyclization to afford pyrrolo[1,2-a]imidazole carbene complex 6 that can be readily oxidized to the corresponding esters 7. When enynylcarbenes 3 e-i are treated with diazafulvene 1, consecutive and diastereoselective [6+2]/cyclopentannulation cyclization reactions take place affording new polycyclic complex systems 8, 9, and 12 that can be appropriately demetallated to the corresponding imidazole-based polyfused systems 10, 11, and 13 respectively. Finally, enynylcarbenes 3 d,f undergo consecutive [6+2]/[5+1] cyclization reactions with diazafulvene 1 and tBuNC, respectively, to yield tetracyclic adducts 14 and 15. All these processes result in high yields and provide a route to the preparation of imidazopyridines and pyrroloimidazoles as well as other polycyclic molecules that contain imidazole groups, which are interesting from a pharmacological and biological point of view. 相似文献
907.
Waters T Huang X Wang XB Woo HK O'hair RA Wedd AG Wang LS 《The journal of physical chemistry. A》2006,110(37):10737-10741
Two polyoxometalate Keggin-type anions, alpha-PM12O40(3-) (M = Mo, W), were transferred to the gas phase by electrospray; their electronic structure and stability were probed by photoelectron spectroscopy. These triply charged anions were found to be highly stable in the gas phase with large adiabatic electron detachment energies of 1.7 and 2.1 eV for M = Mo and W, respectively. The magnitude of the repulsive Coulomb barrier was measured as approximately 3.4 eV for both anions, providing an experimental estimate for the intramolecular Coulomb repulsion present in these highly charged anions. Density functional theory calculations were carried out and compared with the experimental data, providing insight into the electronic structure and valence molecular orbitals of the two Keggin anions. The calculations indicated that the highest occupied molecular orbital and other frontier orbitals for PM12O40(3-) are localized primarily on the mu2-oxo bridging ligands of the polyoxometalate framework, consistent with the reactivity on the mu2-oxo sites observed in solution. It was shown that the HOMO of PW12O40(3-) is stabilized relative to that of PMo12O40(3-) by approximately 0.35 eV. The experimental adiabatic electron detachment energies of PM12O40(3-) (i.e., the electron affinities of PM12O40(2-)) are combined with recent calculations on the proton affinity of PM12O40(3-) to yield O-H bond dissociation energies in PM12O39(OH)2- as approximately 5.1 eV. 相似文献
908.
Granados AM Kreiker J de Rossi RH Fuertes P Torroba T 《The Journal of organic chemistry》2006,71(2):808-810
[reaction: see text] Tricyclic 4-ethyl-5-thioxo-3H,5H-bis[1,2]dithiolo[3,4-d][4,3-b]pyrrol-3-one and monocyclic 3H-1,2-dithiole-3-thione derivatives reacted with Fischer carbene complexes, giving 1,3-dithiin dithioortho esters through insertion of the carbenic carbon into the S-S bond next to the thiocarbonyl function of the substrate. 相似文献
909.
The dimethyltitanocene methylenation of N-acylamides derived from ortho-vinylanilines, ortho-allylaniline, and ortho-vinylbenzylamine provides the corresponding enamides, which upon exposure to the second generation Grubbs ruthenium catalyst give access to indoles, 1,4-dihydroquinolines, and 1,2-dihydroisoquinolines, respectively. This sequential protocol also allows the synthesis of dihydrobenzoazepines, although the ring-closing metathesis (RCM) step is complicated by the alkene isomerization processes. From certain substrates, the direct annulation is observed in the titanium-mediated step, which is likely to occur through an olefin metathesis-intramolecular olefination sequence. 相似文献
910.
Synthesis and characterization of novel mesoporous aluminosilicate MCM-41 containing aluminophosphate building units 总被引:1,自引:0,他引:1
Conesa TD Mokaya R Campelo JM Romero AA 《Chemical communications (Cambridge, England)》2006,(17):1839-1841
Novel MCM-41 aluminosilicate/aluminophosphate materials that exhibit good mesostructural ordering have been synthesized and characterised; the synthesis of these silicoaluminophosphates involved the use of gel mixtures containing amorphous mesoporous aluminosilicate and aluminophosphate phases as precursor. 相似文献