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121.
The radical allylation of an acyclic α-hydroxyketone with allyltributyltin under chelation-controlled conditions is reported. Several reaction conditions were explored, including radical initiators, solvents, and temperatures to improve the yield and the diastereomeric ratio. Some Lewis acids, like magnesium bromide etherate and zinc chloride, gave superior diastereomeric ratios (up to 100:1) and good yields. 相似文献
122.
1-Methyl-3-(benzotriazol-1-ylmethyl)indole (1) undergoes lithiation and 1,4-addition with a variety of alpha,beta-unsaturated ketones and aldehydes. Subsequent treatment with an acidic resin in refluxing 1,4-dioxane causes intramolecular cyclization followed by aromatization to furnish a wide range of 1,3-di-, 2,3-di-, and 1,2,3-trisubstituted carbazoles 6a-j and 8 in moderate to excellent yields. NMR study is described to discriminate between structures of types 6 and 8 on the basis of (1)H-(13)C long-range correlation. Treatment of 1 with styrenes in the presence of zinc bromide results in formal [3 + 2] cycloaddition to give cyclopent[b]indoles 14a-c in good yields. When 1 is first lithiated and reacts with electrophiles, the resulting alkylation products undergo similar [3 + 2] additions with styrenes to give 1-functionalized cyclopent[b]indoles 15 and 16with a high degree of stereoselectivity. 相似文献
123.
Csaba Várhelyi Ion Gănescu Didina Oprescu 《Monatshefte für Chemie / Chemical Monthly》1969,100(1):106-113
Zusammenfassung Es wurden 39 neue Komplexsalze durch doppelte Umsetzung aus wäßrig-alkohol. Lösungen der folgenden Reineckeat-Analoga: [Cr(NCS)4(o-Toluidin)2]–, [Cr(NCS)4(m-Toluidin)2]– und [Cr(NCS)4(p-Toluidin)2]– und Hexammin-, Monoacido-pentammin-und Diacido-tetrammin-kobalt(III)-komplexsalze erhalten.Es wurden in einigen Fällen Abweichungen in physikochemischen Eigenschaften, wie Farbtönung, Kristallform, Löslichkeit und papierchromatographischeR
F-Werte, bei den stellungsisomeren Salzen vom Typus: Kation·[Cr(NCS)4(Toluidin)2] und auch bei den Koordinationsisomerpaaren: [Co(DH)2(o-Toluidin)2][Cr(NCS)4(p-Toluidin)2] und [Co(DH)2(p-Toluidin)2] [Cr(NCS)4(o-Toluidin)2], usw. beobachtet.
Cobalt(III) ammine derivatives of some reineckate analogues with toluidines
39 new complex salts were prepared by double conversion of the reineckate analogues [Cr(SCN)4(o-toluidine)2]–, [Cr(SCN)4(m-toluidine)2]–, and [Cr(SCN)4(p-toluidine)2]– with the hexammine, monoacido-pentammine and diacido-tetrammine complexes of Co(III). In some of the position and coordination isomers deviations from the standard physico-chemical properties, i.e. color, crystal form, solubility and paper chromatographyR f-values were observed.相似文献
124.
Subhradeep Dutta Dr. Jae Hyun Kim Kamal Bhatt Dillon R. L. Rickertsen Dr. Khalil A. Abboud Dr. Ion Ghiviriga Prof. Dr. Daniel Seidel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(1):e202313247
A new strategy to access α-functionalized alicyclic amines via their corresponding imine-BF3 complexes is reported. Isolable imine-BF3 complexes, readily prepared via dehydrohalogenation of N-bromoamines in a base-promoted/18-crown-6 catalyzed process followed by addition of boron trifluoride etherate, undergo reactions with a wide range of organometallic nucleophiles to afford α-functionalized azacycles. Organozinc and organomagnesium nucleophiles add at ambient temperatures, obviating the need for cryogenic conditions. In situ preparation of imine-BF3 complexes provides access to α-functionalized morpholines and piperazines directly from their parent amines in a single operation. α-Functionalized morpholines can be elaborated further, for instance by installing a second substituent in the α′-position. 相似文献
125.
Christine Kunze Ion Neda Matthias Freytag Peter G. Jones Reinhard Schmutzler 《无机化学与普通化学杂志》2002,628(3):545-552
The reaction behaviour of 1, 3, 5‐triaza‐2σ3λ3‐phosphorin‐4, 6‐dionyloxy‐substituted calix[4]arenes towards mono‐ and binuclear rhodium and platinum complexes was investigated. Special attention was directed to structure and dynamic behaviour of the products in solution and in the solid state. Depending on the molar ratio of the reactands, the reaction of the tetrakis(triazaphosphorindionyloxy)‐substituted calix[4]arene ( 4 ) and its tert‐butyl‐derivative ( 1 ) with [(cod)RhCl]2 yielded the mono‐ and disubstituted binuclear rhodium complexes 2 , 3 , and 5 . In all cases, a C2‐symmetrical structure was proved in solution, apparently caused by a fast intramolecular exchange process between cone conformation and 1, 3‐alternating conformation. The X‐ray crystal structure determination of 5 confirmed [(calixarene)RhCl]2‐coordination through two opposite phosphorus atoms with a P ⃜P separation of 345 pm. The complex displays crystallographic inversion symmetry, and the Rh2Cl2 core is thus exactly planar. Reaction of 1 and of the bis(triazaphosphorindionyloxy)‐bis(methoxy)‐substituted tert‐butyl‐calix‐[4]arene ( 7 ) with (cod)Rh(acac) in equimolar ratio and subsequent reaction with HBF4 led to the expected cationic monorhodium complexes 5 and 8 , involving 1, 3‐alternating P‐Rh‐P‐coordination. The cone conformation in solution was proved by NMR spectroscopy and characteristic values of the 1J(PRh) coupling constants in the 31P‐NMR‐spectra. Reaction of equimolar amounts of 4 with (cod)Rh(acac) or (nbd)Rh(acac) led, by substitution of the labile coordinated acetylacetonato and after addition of HBF4, to the corresponding mononuclear cationic complexes 9 and 10 . Only two of the four phosphorus atoms in 9 and 10 are coordinated to the central metal atom. Displacement of either cycloocta‐1, 5‐diene or norbornadiene was not observed. For both compounds, the cone conformation was proved by NMR spectroscopy. Reaction of 4 with (cod)PtCl2 led to the PtCl2‐complex ( 11 ). As for all compounds mentioned above, only two phosphorus atoms of the ligand coordinate to platinum, while two phosphorus atoms remain uncoordinated (proved by δ31P and characteristic values of 1J(PPt)). NMR‐spectroscopic evidence was found for the existence of the cone conformation in the cis‐configuration of 11 . 相似文献
126.
Christine Kunze Detlef Selent Ion Neda Matthias Freytag Peter G. Jones Reinhard Schmutzler Wolfgang Baumann Armin Brner 《无机化学与普通化学杂志》2002,628(4):779-787
New calix[4]arene‐based bis‐phosphonites, bis‐phosphites and bis‐O‐acylphosphites were synthesized and characterized. Treatment of these P‐ligands with selected rhodium and platinum precursors led to mononuclear complexes that were satisfactorily characterized. The solid state structure of the dirhodium(I) complex 14 has been determined by X‐ray diffraction. The two rhodium centres are bridged by two chloro ligands; one rhodium atom is further coordinated by calix[4]arene phosphorus atoms and the other by cyclooctadiene. The new calix[4]arene P‐ligands were tested in the Rh(I) catalyzed hydroformylation of 1‐octene. All Rh(I) complexes catalyzed the reaction leading to high chemoselectivity with regard to the formation of aldehydes. Yields and n/iso‐selectivities depended on the reaction conditions. Average yields of 80 % and n/iso‐ratios of about 1.3 to 1.5 were observed. High yields of aldehydes can be achieved using the methoxy substituted P‐ligands at low Rh:ligand ratios. 相似文献
127.
128.
Bovine heart cytochrome c electrochemistry was investigated by cyclic voltammetry using gold electrodes modified by self-assembled monolayers of cysteine
and some of its derivatives, including glutathione. Glutathione shows a peculiar dependence of the facilitating ability on
the oxidation state of the sulfur functionality. Whereas the disulfide form acts as an efficient facilitator, the thiol form
is completely inactive. This behavior was accounted for by the lower stability of adsorbed thiol layers as compared to disulfide
layers. Apparently, small molecules of cysteine derivative form rather stable adsorbed layers with a high degree of dimer
formation. Conversely, reduced glutathione is not able to turn into the disulfide form in the adsorbed layer. Consequently,
only the layer produced by the adsorption of the disulfide form itself is stable enough for promoting direct electron transfer
reactions of cyt c.
Electronic Publication 相似文献
129.
4,5-Benzo-2-{[2-(dimethylamino)ethyl]methylamino}-3-methyl-1,3,2-oxazaphosphorinan-6-one – Preparation, Sulfuration, and Molecular Structure of a Tetracarbonyl Molybdenum Derivative The synthesis of the title compound 4 is described. It reacts with sulfur to yield the thiophosphoryl derivative 5 . The structure of the molybdenum(0) complex 6 , containing 4 as a bidentate ligand, was established by X-ray analysis and is compared to that of the related 2-{[2-(dimethylamino)ethyl]methyl-amino}-1,3,2-benzodioxaphosphole-tetracarbonylchromium(0)-complex 7 [1]. 6 , similarly to 7 , shows a nearly rectangular ?bite”? angle, with 4 functioning as a chelating ligand, coordinating to Mo(0) via P(III) and the nitrogen atom of the NMe2 group. The heterocyclic part of the ligand displays a distorted envelope configuration. 相似文献
130.
We examine the temperature fields of human enamel [Yu D, Fox JL, Hsu J, Lynn Powell G, Higuchi WI. Computer simulation of surface temperature profiles during CO2 laser irradiation of human enamel. Opt Eng 1993; 32(2)] during multi-modes CO2 laser irradiation. For this we use the integral transform method as well as direct and inverse Laplace transform [Oane M, Sporea D. Temperature profiles modeling in IR optical components during high power laser irradiation. Infrared Phys Technol 2001; 42(1): 31–40; Oane M, Sporea D. Study of heat transfer in IR optical components during CO2 laser irradiation. Proc SPIE 2001; 4430: 898–904; Oane M. Mathematical modeling of the thermal field distributions in solids under multiple laser irradiations. Proc SPIE 2003; 5227: 329–34; Oane M, Apostol I, Timcu A. Temperature field modeling in laser heated metals for laser cleaning of surfaces. Proc SPIE 2003; 5227: 323–8]. The enamel block is modeled as homogeneous cylinder in three dimensions. Results indicate that (i) the thermal field depends on multi-modes structure; (ii) heat transfer coefficient plays an important role in temperature distribution. 相似文献