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61.
Shoichi Katsuta Tokutaro Kimura Yoshihiro Kudo Ryozo Nakagawa Yasuyuki Takeda Mikio Ouchi 《Journal of inclusion phenomena and macrocyclic chemistry》1998,31(2):89-98
The overall extraction constants (Kex) of uni- andbivalent metal picrates with 15-(2,5-dioxahexyl)-15-methyl-16-crown-5(L16C5) were determined between benzene and water at 25°C. TheKex values were analyzed into the constituent equilibriumconstants, i.e., the extraction constant of picric acid, the distributionconstant of the crown ether, the stability constant of the metalion–crown ether complex in water, and the ion-pair extraction constantof the complex cation with the picrate anion. The Kex valuedecreases in the orders Ag+ > Na+ >Tl+ > K+ > Li+ andPb2+ > Ba2+ > Sr2+ for theuni- and bivalent metals, respectively, which are the same as those observedfor 16C5. The extraction selectivity was found to be governed by theselectivity of the ion-pair extraction of the L16C5–metal picratecomplex rather than by that of the complex formation in water. Theextraction ability of L16C5 is smaller for all the metals than that of 16C5,which is mostly attributed to the higher lipophilicity of L16C5. Differencesin the extraction selectivity between L16C5 and 16C5 were observed for thebivalent metals but little for the univalent metals. The side-arm effect onthe extraction selectivity was interpreted on the basis of the negativecorrelation between the effect on the complex stability constant in waterand that on the ion-pair extraction constant. 相似文献
62.
Prof. Dr. Tomoaki Tanase Dr. Kanako Nakamae Haruka Miyano Prof. Dr. Yasuyuki Ura Prof. Dr. Yasutaka Kitagawa Dr. Shiho Yada Prof. Dr. Tomokazu Yoshimura Prof. Dr. Takayuki Nakajima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(47):12078-12103
A series of the octapalladium chains supported by meso-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2 (meso-dpmppm) ligands, [Pd8(meso-dpmppm)4(L)2](BF4)4 (L=none ( 1 ), solvents: CH3CN ( 2 a ), dmf ( 2 b ), dmso ( 2 c ), RN≡C: R=Xyl ( 3 a ), Mes ( 3 b ), Dip ( 3 c ), tBu ( 3 d ), Cy ( 3 e ), CH3(CH2)7 ( 3 f ), CH3(CH2)11 ( 3 g ), CH3(CH2)17 ( 3 h )) and [Pd8(meso-dpmppm)4(X)2](BF4)2 (X=Cl ( 4 a ), N3 ( 4 b ), CN ( 4 c ), SCN ( 4 d )), were synthesized by using 2 a as a stable good precursor, and characterized by spectroscopic (IR, 1H and 31P NMR, UV-vis-NIR, ESI-MS) measurements and X-ray crystallographic analyses (for 1 , 2 a , b , 3 a , b , e , f , 4 a – d ). On the basis of DFT calculations on the X-ray determined structure of 2 b ( [2b-Pd8]4+ ) and the optimized models [Pd8(meso-Ph2PCH2P(H)CH2P(H)CH2PH2)4(CH3CN)2]4+ ( [Pd8Ph8]4+ ) and [Pd8(meso-H2PCH2P(H)CH2P(H)CH2PH2)4(CH3CN)2]4+ ( [Pd8H8]4+ ), with and without empirically calculating dispersion force stabilization energy (B3LYP-D3, B3LYP), the formation energy between the two Pd4 fragments is assumed to involve mainly noncovalent interactions (ca. −70 kcal/mol) with four sets of interligand C−H/π interactions and Pd⋅⋅⋅Pd metallophilic one, while electron shared covalent interactions are almost canceled out within the Pd8 chain. All the compounds isolated are stable in solution and exhibit characteristic absorption at ∼900 nm, which is assignable to a spin allowed HOMO to LUMO transition, and shows temperature dependent intensity change with variable absorption coefficients presumably due to coupling with some thermal vibrations. The structures and electronic states of the Pd8 chains are found finely tunable by varying the terminal capping ligands. In particular, theoretical calculations elucidated that the HOMO-LUMO energy gap is systematically related to the central Pd−Pd distance (2.7319(6)–2.7575(6) Å) by two ways with neutral ligands L ( 1 , 2 , 3 ) and with anionic ligands X ( 4 ), which are reflected on the NIR absorption energy of 867–954 nm. The isocyanide terminated Pd8 complexes ( 3 ) further reacted with excess of RNC (6 eq) to afford the Pd4 complexes, [Pd4(meso-dpmppm)2(RNC)2](BF4)2 ( 13 ), and the cyclic voltammograms of 2 a (L=CH3CN), 3 , and 13 (R=Xyl, Mes, tBu, Cy) demonstrated wide range redox behaviors from 2{Pd4}4+ to 2{Pd4}0 through 2{Pd4}2+↔{Pd8}4+, {Pd8}3+, and {Pd8}2+ strings. The oxidized complexes, [Pd4(meso-dpmppm)2(RNC)3](BF4)4 ( 16 ), were characterized by X-ray analyses, and the two-electron reduced chain of [Pd8(meso-dpmppm)4](BF4)2 ( 7 ) was analyzed by spectroscopic and electrochemical techniques and DFT calculations. Reactions of 2 a with 1 equiv. of aromatic linear bisisocyanide (BI) in CH2Cl2 deposited insoluble coordination polymers, {[Pd8(meso-dpmppm)4(BI)](BF4)4}n ( 5 ), and interestingly, they were soluble in acetonitrile, 31P{1H} and 1H DOSY NMR spectra as well as SAXS curves suggesting that the coordination polymers may exist in acetonitrile as dynamically 1D self-assembled coordination polymers comprising ca. 50 units of the Pd8 rod averaged within the timescale. 相似文献
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64.
Prof. Tomoaki Tanase Miho Tanaka Mami Hamada Yuka Morita Dr. Kanako Nakamae Prof. Yasuyuki Ura Prof. Takayuki Nakajima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(35):8219-8224
A new linear tetraphosphine containing a PNP phosphazane bridge, rac-bis[(diphenylphosphinomethyl)phenylphosphino]phenylamine (rac-dpmppan), was synthesized and utilized to support a series of Pd/Pt mixed metal tetranuclear chains, [Pd4−nPtn(μ-rac-dpmppan)2(XylNC)2](PF6)2 (XylNC=xylyl isocyanide; n=0: Pd4 ( 1 ), 1: PtPd3 ( 2 ), 2: PtPd2Pt ( 3 ), 2: Pt2Pd2 ( 4 ), 3: Pt2PdPt ( 5 )), in which the number and positions of additional Pt atoms were successfully controlled depending on the respective synthetic procedures using transformations from 1 to 3 through 2 and from 4 to 5 by redox-coupled exchange reactions. The 31P{1H} NMR and ESI mass spectra and X-ray diffraction analyses revealed almost identical tetranuclear structures, with slight contraction of metal-metal bonds according to incorporation of Pt atoms. The electronic absorption spectra of 1 – 5 exhibited characteristic bands at 635–510 nm with an energy propensity depending on the number and positions of Pt centres, which were assigned to HOMO (dσ*σσ*) to LUMO (dσ*σ*σ*) transition by theoretical calculations. The present results demonstrated that the electronic structures of Pd/Pt mixed-metal tetranuclear complexes are finely tuned as orbital-overlapping alloyed metal chains by atomically precise Pt incorporation in the Pd4 chain. 相似文献
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Abstract The non-linear dielectric relaxation spectroscopy has been recently developed and applied to soft materials such as polymers. We have applied this new method to the S*C phases of some ferroelectric liquid crystals. Under a weak AC electric field, the original and third order harmonic frequency components of electric displacement are proportional to the first and third powers of the applied electric field, respectively. The linear spectrum obtained from the original frequency component shows the relaxation of Debye type and the third order non-linear spectrum shows the relaxation with an extended form of Debye type to the non-linear case. The third order non-linear dielectric increment is found to be negative, which implies that the dielectric non-linearity of the liquid crystal in the S*C phase is due to the saturation of molecular dipole moments induced by the applied electric field. The temperature dependence of the linear and third order non-linear spectra in the S*C phase are also studied. Both spectra do not change their forms much through the whole temperature range of the S*C phase. In the vicinity of the SA–S*C transition temperature, the critical behaviour is more remarkable in the third order spectrum than in the linear one. 相似文献
69.
Polymerizations of cyclooctene, 5-methyl, 5-chloro-, and 5-methoxycyclooctenes were studied. Cyclooctene (CO) and 5-methylcyclooctene (MCO) provided high polymers in 80% yield with the use of WCl6/AlEti.B Clu5 or WCl6/AlEtCl2 catalyst. 5-Chlorocyclooctene gave oligomer in 50% yield with WCl6/AlEt2Cl catalyst. Neither polymer nor oligomer was produced from 5-methoxycyclooctene. These polymers were found to be produced through a ring-opening mechanism. The ratio of cis to trans structure in poly(CO) and poly(MCO) was determined by measurements of the decoupled ′H-NMR spectrum. Poly(CO) containing more than 50% trans structure was a crystalline solid at room temperature, while the polymer containing 30% of trans structure did not crystallize at room temperature. Poly(MCO) was amorphous, regardless of the content of trans structure. Poly(CO) and poly(MCO) obtained with MoCU/AlEtaCl or MoCU/AlEtCb catalyst contained no carbon-carbon double bond, and a vinyl polymerization mechanism was expected for this system. 相似文献
70.
Abstract Three types of nematogenic compound, 4-[2-(trans-4-alkylcyclohexyl)ethyl]-4′-alkyltolanes, 2-fluoro-4-[2-(trans-4-alkylcyclohexyl)ethyl]-4′-alkyltolanes and 4-[2-(trans-4-alkylcyclohexyl)ethyl]-4′-halogenotolanes, have been synthesized and their transition temperatures and enthalpies determined. Their bulk viscosity and birefringence have been estimated from those of mixtures with other liquid-crystalline compounds. These compounds have been found to be excellent materials for twisted nematic displays, because of their wide nematic temperature range, high birefringence (Δn = 0·26), and low viscosity (η = 21 cP at 20°C). Several related compounds having other central linkages, namely -CH2O-, a single bond or -COO-, in place of the 1,2-ethylene group, have also been studied. 相似文献