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991.
Ezequiel?P.?M.?LeivaEmail author C.?G.?Sánchez 《Journal of Solid State Electrochemistry》2003,7(9):588-592
In the present work, an important point concerning the NEMCA effect is addressed. We analyse the reasons why the changes in the work function of the gas exposed catalyst-electrode surface are one to one related to the changes in the catalyst working electrode potential E with respect to a reference electrode. It is concluded that this is due to the unique properties of the catalyst/solid electrolyte interface: the structure of the double layer in this region is very different from that in liquid electrolytes, being the potential difference at this interface mainly determined by the specific adsorption of the mobile species in the solid electrolyte.
相似文献
Ezequiel P. M. LeivaEmail: |
992.
Chunli Zhang Xueshen Liu Peizhu Ding Yueying Qi 《Journal of mathematical chemistry》2006,39(3-4):451-463
Asymptotic boundary condition (ABC) of laser-atom interaction presented recently is applied to transform the initial value problem of the time-dependent Schrödinger equation (TDSE) in infinite space into the initial and boundary value problem in the finite space, and then the TDSE is discretized into linear canonical equations by substituting the symmetry difference quotient for the 2-order partial derivative. The canonical equation is solved by symplectic algorithm. The ground state and the equal weight coherent superposition of the ground state and the first excited state have been taken as the initial conditions, respectively, while we calculate the population of bound states, the evolution of average distance and the high-order harmonic generation (HHG). The conversion efficiency of HHG can be enhanced by initial coherent superposition state and moderate laser intensities 相似文献
993.
By adopting the convention that shared double bonds in polycyclic conjugated hydrocarbons contribute with one -electron and unshared ones with two -electrons, a partition of -electrons in each ring (-electron content, EC) can be obtained by averaging over all Kekulé structures, which are assumed to have equal weights. This affords a simple measure of local aromaticity that is comparable with other such local aromaticity indices in polycyclic benzenoids. 相似文献
994.
Sergey?P.?BabailovEmail author Dmitry?A.?Mainichev Lubov?D.?Nikulina Svetlana?S.?Petrova 《Journal of inclusion phenomena and macrocyclic chemistry》2005,51(1-2):73-78
Earlier the intramolecular inversion of the 18-crown-6 molecules was found in the complex ion pairs [Ln(ptfa)2 (18-crown-6)]+ [Ln(ptfa)4]− (H2O)4 where Ln = La(1), Ce (2), Pr (3), Nd (4), and ptfa is 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione. In this work the peculiarities of the molecular structure and dynamics were studied for [Eu(ptfa)2 (18-crown-6)]+ [Eu(ptfa)4]− (H2O)4 (5) by NMR spectroscopy techniques. Through VT-NMR spectra analysis the temperature dependence was obtained for the rate constant. The free energy ΔG‡(320) of 18-crown-6 ring inversion activation was found to be 65 ± 5 kJ mol−1 for 5 in CDCl3. This result is comparable with the earlier data [S.P. Babailov and D.A. Mainichev: J. Inclusion Phenom. Macrocyclic Chem. 43, 187–193 (2002)] for complexes 2, 3, 4 in deuterated toluene (ΔG‡(320)=65 ± 9, 64 ± 9, 64 ± 9 kJ mol−1 respectively). It was found by relaxation NMR spectroscopy that the effective distance between Ln and protons of the crown molecule is 4.5 ± 0.2 Å. The analysis of structural parameters testifies that the crown ether and chelated anions are in the first coordination sphere of a Ln cation. Obtained geometrical parameters show that the complex cations of Eu, Ce and Pr have similar spatial structures.This revised version was published online in July 2005 with a corrected issue number. 相似文献
995.
I. Kiricsi S. Kh. Akopyan A. V. Mikhailov H. F?rster 《Reaction Kinetics and Catalysis Letters》1990,42(1):145-150
Formation of alkenylcarbenium ions has been proved during transformation of allyl alcohol on zeolite HZSM-5.
HZSM-5.相似文献
996.
Summary A practicable method was developed for the routine determination of formaldehyde in air. Formaldehyde is sampled in small sampling tubes filled with Chromosorb P, coated with 2,4-dinitrophenylhydrazine (= DNPH). The sorbent is extracted with acetonitrile, and the different DNPhydrazones were separated by reversed-phase HPLC. UV-detection at = 345 nm was compared with electrochemical detection. The detection limit was 100 pg for UV- and 50 pg for electrochemical detection with a linear range of more than 3 decades, respectively. For the determination of formaldehyde in air the detection limit is 10 ppb with an average recovery of 99.3% and an estimated relative standard deviation S of 1.5%. This method was compared with the sampling by impingers using the same separation and detection method.
Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday 相似文献
Einige neue Aspekte einer HPLC-Methode zur Spurenbestimmung von Formaldehyd in Luft
Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday 相似文献
997.
998.
Addition of dimethyl phosphite to racemic 3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene-2-carboxaldehyde gives almost exclusively one diastereomer of the corresponding α-hydroxyphosphonate (d.r. ?96:4). Its absolute configuration (S, Rp)-(R, Sp) was established by X-ray diffraction. 相似文献
999.
Monodisperse thermosensitive particles prepared by emulsifier-free emulsion polymerization with microwave irradiation 总被引:2,自引:0,他引:2
The emulsifier-free emulsion polymerization of styrene (St) and N-isopropylacrylamide (NIPAAm) was successfully carried out with microwave irradiation, and the monodisperse thermoresponsive
poly(styrene-co-N-isopropylacrylamide) (poly(St-co-NIPAAm)) particles with diameters in the range 100–130 nm were prepared. The morphology, size and size distribution of the
poly(St-co-NIPAAm) particles were characterized by transmission electron microscopy, scanning electron microscopy (SEM) and photon correlation
spectroscopy (PCS), respectively. The results showed that poly(St-co-NIPAAm) particles had spherical morphology, and the poly(St-co-NIPAAm) particles prepared by emulsifier-free emulsion polymerization with microwave irradiation were smaller, more uniform
than those obtained with conventional heating. The hydrodynamic diameters of poly(St-co-NIPAAm) particles were decreased as the temperature increased from 25 °C to 40 °C, and poly(St-co-NIPAAm) particles collapsed remarkably at 32 °C, which is the lower critical solution temperature of the poly(N-isopropylacrylamide). The morphology of the assembled poly(St-co–NIPAAm) particles was observed by SEM, it was found that monodisperse poly(St-co-NIPAAm) particles could assemble to form the two-dimensional order structures. 相似文献
1000.
A series of fifteen complexes of the type [Fe(RRNCS2)3] with symmetric (R=R=n- C6H13, n-C8H17, CH2–CH=;CH2, C6H5, C6H11 and C6H5CH2), unsymmetric (R = CH3; R = n-C4H9, C6H11, C6H5 and R = C2H5; R = n-C4H9, C6H11, C6H5 and i-C3H7) and ring substituents (RNR=pyrrolidyl and piperidyl) have been synthesized and their magnetic moments and Mössbauer spectra recorded from room temperature (RT) to liquid nitrogen temperature (LNT). Room temperature Mössbauer spectra of all the complexes exhibit an asymmetric doublet, which could be resolved into two doublets, each corresponding to low and high spin states in equilibrium. The crystal structure of tris(N, N-diallyldithiocarbamato)iron(III) shows it to be monoclinic with trigonally distorted octahedral geometry and space group C2/c. Fe–S stretching vibrations in the far i.r. region also show equilibria, HS LS. Depending on the nature of the alkyl group substituent, variable temperature magnetic moment and Mössbauer spectral studies, all the complexes may be divided into three groups; high spin complexes exhibiting spin-crossover (6A1g 2T2g), high spin complexes exhibiting spin transition (6A1g 4T1g) and intermediate spin complexes showing spin transition (4A1g 2T2g). On the basis of areas of the two doublets corresponding to high and low spin states, their percent contributions were calculated. Furthermore, magnetic moments of the equilibrium mixture calculated on the basis of respective areas compare well with the experimentally determined eff values. EQ values for both high and low spin states show linear decrease with increasing temperature. 相似文献