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101.
Izod K Liddle ST Clegg W Harrington RW 《Dalton transactions (Cambridge, England : 2003)》2006,(28):3431-3437
The secondary phosphines Ar(C6H4-2-CH2NMe2)PH [Ar = mes (3), Tripp (4)] may be isolated in good yields from reactions between Li(C6H4-2-CH2NMe2) and the respective dichlorophosphine, followed by reduction with LiAlH4 [mes = 2,4,6-Me3C6H2, Tripp = 2,4,6-Pri3C6H2]. Metalation of either 3 or 4 with BunLi gives the corresponding lithium compound; the lithium derivative of 3 was isolated as the separated ion pair complex [Li(12-crown-4)2][(mes)(C6H4-2-CH2NMe2)P].THF (5). The lithium complexes Ar(C6H4-2-CH2NMe2)PLi undergo metathesis reactions with either NaOBut or KOBut to give the heavier alkali metal phosphides {Ar(C6H4-2-CH2NMe2)P}M.1/2OEt2 [Ar = mes, M = Na (8), K (9); Ar = Tripp, M = K (10)]. Metathesis reactions between 9 and LaI3(THF)4 give only intractable products; in contrast, a metathesis reaction between 10 and LaI3(THF)4 yields the heteroleptic complex {(Tripp)(C6H4-2-CH2NMe2)P}2LaI (11). Compound 11 reacts cleanly with K{N(SiMe3)2} to give {(Tripp)(C6H4-2-CH2NMe2)P}2La{N(SiMe3)2} (14). Compounds 3-5, 8-11 and 14 have been characterised by multi-element NMR spectroscopy; in addition, compounds 5, 11 and 14 have been studied by X-ray crystallography. 相似文献
102.
Argent SP Adams H Riis-Johannessen T Jeffery JC Harding LP Clegg W Harrington RW Ward MD 《Dalton transactions (Cambridge, England : 2003)》2006,(42):4996-5013
The coordination chemistry of a series of di- and tri-nucleating ligands with Ag(I), Hg(I) and Hg(II) has been investigated. Most of the ligands contain two or three N,N'-bidentate chelating pyrazolyl-pyridine units pendant from a central aromatic spacer; one contains three binding sites (2 + 3 + 2-dentate) in a linear sequence. A series of thirteen complexes has been structurally characterised displaying a wide range of structural types. Bis-bidentate bridging ligands react with Ag(I) to give complexes in which Ag(I) is four-coordinate from two bidentate donors, but the complexes can take the form of one-dimensional coordination polymers, or dinuclear complexes (mesocate or helicate). A tris-bidentate triangular ligand forms a complicated two-dimensional coordination network with Ag(I) in which Ag...Ag contacts, as well as metal-ligand coordination bonds, play a significant role. Three dinuclear Hg(I) complexes were isolated which contain an {Hg2}2+ metal-metal bonded core bound to a single bis-bidentate ligand which can span both metal ions. Also characterised were a series of Hg(II) complexes comprising a simple mononuclear four-coordinate Hg(II) complex, a tetrahedral Hg(II)4 cage which incorporates a counter-ion in its central cavity, a trinuclear double helicate, and a trinuclear catenated structure in which two long ligands have spontaneously formed interlocked metallomacrocyclic rings thanks to cyclometallation of two of the Hg(II) centres. 相似文献
103.
Aldridge S Kays DL Al-Fawaz A Jones KM Horton PN Hursthouse MB Harrington RW Clegg W 《Chemical communications (Cambridge, England)》2006,(24):2578-2580
The reaction of (eta(5)-C5H5)Fe(CO)2B(C6F5)2 with CO has been shown to proceed via ligand substitution at the metal with accompanying transfer of the boryl fragment (via C-H insertion) to the Cp ring, thereby generating the zwitterion [eta(5)-C5H4B(C6F5)2H]Fe(CO)3 in quantitative yield. 相似文献
104.
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106.
Although it is known that growing cracks will interact with pores, it is unclear whether the magnitude of this effect is sufficient to influence the fracture energy. To study this, experiments have been carried out where cracks have been grown through simple distributions of pores in poly(methyl methacrylate). These show that the applied force required to grow the crack between two pores can be greater than that required to grow the crack in the pore-free material. Direct observation during crack growth shows that this increase in applied force is associated with the crack front becoming curved. Based on these observations, the effect of equiaxed pores on the fracture energy of brittle materials has been quantitatively described. The analysis predicts how the relative fracture energy should be influenced by the pore volume fraction, and that it should be independent of the size of the pores or the fracture energy of the matrix. These predictions give good agreement with experimental measurements in different ceramic materials, in which the microstructure of the matrix surrounding the pores does not change with pore volume fraction. 相似文献
107.
William Clegg Dale R. Harbron Brian P. Straughan 《Journal of chemical crystallography》1990,20(1):17-22
The crystal structure of [Zn(O2CC(CH3)CHCH3)0.54(O2CC6H5)1.46]x has been determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system, space group P21/c witha=10.311(1),b=13.170(1),c=19.000(2) Å,=91.895(7)°,V=2578.7 Å3,Z=4,D
x=1.525g cm–3, (Mo K)=0.71073 Å,=1–95 mm–1, F(000)=1206,T=295K,R=0.046 for 4548 unique reflections. The two different carboxylates are randomly scrambled along a one dimensional polymer, made up of binuclear units connected by a syn-anti carboxylate bridge. Each binuclear unit contains three syn-syn carboxylates which bridge two zinc atoms. Vibrational data indicate that [Zn(O2CC(CH3)CHCH3)2]x has the same polymeric structure; orientation of tiglate is the same as for the mixed ligand compound. Recrystallization of mixed carboxylate species produces either an alteration in carboxylate ligand ratio, or a total separation of the two carboxylates, giving two different compounds. 相似文献
108.
Skabara PJ Pozo-Gonzalo C Lardiés Miazza N Laguna M Cerrada E Luquin A González B Coles SJ Hursthouse MB Harrington RW Clegg W 《Dalton transactions (Cambridge, England : 2003)》2008,(23):3070-3079
A series of new metal (M) dithiolene complexes bearing terthiophene (3, 12, M = Ni; 4, M = Pd; 5, 6, M = Au) and 2,5-bis(para-methoxyphenyl)thiophene units (14, M = Ni; 15, 16, M = Au; 17, M = Pd) have been synthesised in 38-99% yield. The electrochemical properties of the materials have been characterised by cyclic voltammetry and UV-vis spectroelectrochemistry. The nickel complexes possess low oxidation potentials (-0.12 to -0.25 V vs Ag/AgCl) due to the electron-rich dithiolene centres and all complexes display ligand-based redox activity. The terthiophene derivatives have been polymerised by electrochemical oxidation to give stable films with, in the case of poly(3), broad absorption characteristics. Charge transfer materials have been isolated from 14 and 16 with conductivities in the range 9 x 10(-6) to 7 x 10(-8) S cm(-1). 相似文献
109.
Hanford KL Mitchem L Reid JP Clegg SL Topping DO McFiggans GB 《The journal of physical chemistry. A》2008,112(39):9413-9422
Aerosol optical tweezers are used to simultaneously characterize and compare the hygroscopic properties of two aerosol droplets, one containing inorganic and organic solutes and the second, referred to as the control droplet, containing a single inorganic salt. The inorganic solute is either sodium chloride or ammonium sulfate and the organic component is glutaric acid. The time variation in the size of each droplet (3-7 microm in radius) is recorded with 1 s time resolution and with nanometre accuracy. The size of the control droplet is used to estimate the relative humidity with an accuracy of better than +/-0.09%. Thus, the Kohler curve of the multicomponent inorganic/organic droplet, which characterizes the variation in equilibrium droplet size with relative humidity, can be determined directly. The measurements presented here focus on high relative humidities, above 97%, in the limit of dilute solutes. The experimental data are compared with theoretical treatments that, while ignoring the interactions between the inorganic and organic components, are based upon accurate representations of the activity-concentration relationships of aqueous solutions of the individual salts. The organic component is treated by a parametrized fit to experimental data or by the UNIFAC model and the water activity of the equilibrium solution droplet is calculated using the approach suggested by Clegg, Seinfeld and Brimblecombe or the Zdanovskii-Stokes-Robinson approximation. It is shown that such an experimental strategy, comparing directly droplets of different composition, enables highly accurate measurements of the hygroscopic properties, allowing the theoretical treatments to be rigorously tested. Typical deviations of the experimental measurements from theoretical predictions are shown to be around 1% in equilibrium size, comparable to the variation between the theoretical frameworks considered. 相似文献
110.
Zhu BX Zhang QL Zhang YQ Zhu T Clegg JK Lindoy LF Wei G 《Inorganic chemistry》2008,47(21):10053-10061
The interaction of the diastereopure N,N'-bis(acetylacetone)cyclohexanediimine ligands, L(1)(1R,2R), L(2)(1S,2S), and their 1:1 mixture, with Zn(II) chloride has been investigated. Four new coordination polymers, [ZnL(1)Cl2 x H2O]n (1), [ZnL(2)Cl2 x H2O]n (2), [ZnL(2)Cl2]n (3), and [Zn6(L(2))6Cl12 x 2 H2O]n (4), each consisting of an infinite single helical chain displaying different pitches and/or handedness have been isolated. The complexed Schiff base ligands are present in their deprotonated enol forms, and the nitrogen atoms, which do not coordinate, are protonated because of proton transfer from the adjacent enol oxygen (coupled with concomitant N-H...O bond formation); each bound ligand is thus pseudo-zwitterionic. The respective zinc centers are bound to two chloro ligands and two oxygen donors from acacH-imine units belonging to different N,N'-bis(acetylacetone)cyclohexanediimine ligands such that the coordination at each zinc is distorted tetrahedral. Compounds 1 and 2, prepared from enantiopure L(1) and L(2), respectively, are enantiomers with similar structures, with the helical pitch in each being 17.0 A. Overall, the structure of 3 may be described as a one-dimensional helical chain with a pitch of 17.3 A, with each period corresponding to two L(2) ligands and two metal centers. The structure of [(Zn6L(2)6Cl12) x 2 H2O]n (4) contains six Zn(II) centers connected via six L(2) ligands to form a "bowed" helical repeat unit, with the pitch of the helix corresponding to 43.5 A. Supramolecular (intra- and intermolecular) aspects of all these unusual polymeric structures are discussed. Finally, the synthesis and characterization of an unprecedented six zinc-node discrete supramolecular assembly, [Zn6(L(1))3(L(2))3Cl12] (5), incorporating a 78-membered metallacycle, is also reported. 相似文献