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791.
Rajesh Kumar A. K. Gupta M. P. Kaushik 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):765-771
A new rapid, efficient, solvent-free, microwave-assisted, and high-yielding method for the synthesis of N,N-dialkyl-P-alkylphosphonamidic anhydrides has been developed. The method involves the use of 4-dimethylaminopyridine and water under microwave irradiation. The reaction of N,N-dialkylaminoalkyl/phenyl phosphonochloridates 2a–h with 4-dimethylaminopyridine (DMAP) gave pyridinium salts, which were converted into N,N-dialkyl-P-alkylphosphonamidic anhydrides 4a–h. 相似文献
792.
Shital K. Chattopadhyay Kaushik Sarkar Latibuddin Thander Shankar P. Roy 《Tetrahedron letters》2007,48(35):6113-6116
A route to two epimeric hitherto unknown 2-piperidinylglycine derivatives, as precursors of carbocyclic β-lactam derivatives, has been developed, which features diastereoselective addition of allyl metal reagents to an N-allylimine derivative of Garner’s aldehyde and ring-closing metathesis as key steps. 相似文献
793.
Some bis(η5-cyclopentadienyl) N-aryl-ditbiocarbamato chloro oxotungsten (VI) complexes of the type (C5H5)2 WO (S2CNHR) Cl (R =o-, m-, p-tolyl and Ph) have been prepared by the reaction of stoichiometric amounts of bis (η5-cyclo-pentadienyl) oxotungsten(VI) dichloride with sodium salts of dithiocarbamic acids in refluxing tetrahydrofuran. The
corresponding indenyl complexes of the type (C9H7)2WO (S2CNHR) Cl were similarly synthesised by refluxing equimolar quantities of bis (η5-indenyl) oxotungsten(VI) dichloride and sodium dithiocarbamate in tetrahydrofuran. Infrared spectral studies demonstrate
that in these complexes dithiocarbamate ligands are bidentate. Electronic spectra, magnetic susceptibility and elemental analysis
have also been carried out for the complexes. 相似文献
794.
Aerobic oxidation of the Mn(II) complex [Mn(Papy3)(H2O)](ClO4) (1, PaPy3- is the anion of the designed ligand N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamide) in acetonitrile affords the (mu-oxo)dimanganese(III) complex [(Mn(PaPy3))2(mu-O)](ClO4)2 (3) in high yield. The unsupported single oxo bridge between the two high-spin Mn(III) centers in 3 is readily cleaved upon addition of proton sources such as phenol, acetic acid, and benzoic acid, and complexes of the type [Mn(PaPy3)(L)](ClO4) (5, L = PhO-; 6, L = AcO-; 7, L = BzO-) are formed. The basicity of the bridge is evident by the fact that simple addition of methanol to a solution of 3 in acetonitrile affords the methoxide complex [Mn(PaPy3)(OMe)](ClO4) (4). The structures of 3-5 and 7 have been determined. Passage of NO through a solution of 3 in acetonitrile produces the [Mn-NO]6 nitrosyl [Mn(PaPy3)(NO)](ClO4) (2) via reductive nitrosylation. Complexes 4-7 also afford the [Mn-NO]6 nitrosyl 2 upon reaction with NO. In the latter case, the anionic O-based ligands (such as MeO- and PhO-) act as built-in bases and promote reductive nitrosylation of the Mn(III) complexes. 相似文献
795.
PtIV and PdII complexes [Pt(L)2Cl2] and [Pd(HL)Cl2] [HL = salicyclaldehyde morpholine N-thiohydrazone (HL1), benzaldehyde morpholine N-thiohydrazone (HL2), acetophenone morpholine N-thiohydrazone (HL3), p-methylacetophenone morpholine N-thiohydrazone (HL4), cinnamaldehyde morpholine N-thiohydrazone (HL5), cyclohexanone morpholine N-thiohydrazone (HL6), benzaldehyde aniline N-thiohydrazone (HL7), benzaldehyde N-(methyl, cyclohexyl)-thiohydrazone (HL8) and benzaldehyde N-(ethyl, cyclohexyl)-thiohydrazone (HL9)] were prepared in MeOH and characterized by elemental analysis, i.r., electronic, 1H-n.m.r. and 13C-n.m.r. spectral data. For some of the complexes cyclic voltammetric and thermal studies were carried out. The in vitro antitumor activity of some complexes was measured. 相似文献
796.
Tris-N(ethyl, m-tolyl) dithiocarbamato complexes of arsenic(III), antimony(III) and bismuth(III) abbreviated as As(S2CNRR′)3 Sb(S2CNRR′)3 and Bi(S2CNRR′)3, respectively, where R C2H5 and R′ m-C6H4CH3, have been synthesized. These complexes have been characterized on the basis of elemental analyses, molecular weight determinations, conductance measurements and infrared spectral studies. Thermal studies of these complexes have been carried out in nitrogen and air to determine their modes of decomposition. Kinetic parameters, such as apparent activation energy and order of reaction, have been determined by the graphical method of Coats and Redfern [1]. 相似文献
797.
Neeraj Soni Shivendra Singh Shubham Sharma Gayatri Batra Kush Kaushik Chethana Rao Navneet C. Verma Bhaskar Mondal Aditya Yadav Chayan K. Nandi 《Chemical science》2021,12(10):3615
The structure–function relationship, especially the origin of absorption and emission of light in carbon nanodots (CNDs), has baffled scientists. The multilevel complexity arises due to the large number of by-products synthesized during the bottom-up approach. By performing systematic purification and characterization, we reveal the presence of a molecular fluorophore, quinoxalino[2,3-b]phenazine-2,3-diamine (QXPDA), in a large amount (∼80% of the total mass) in red emissive CNDs synthesized from o-phenylenediamine (OPDA), which is one of the well-known precursor molecules used for CND synthesis. The recorded NMR and mass spectra tentatively confirm the structure of QXPDA. The close resemblance of the experimental vibronic progression and the mirror symmetry of the absorption and emission spectra with the theoretically simulated spectra confirm an extended conjugated structure of QXPDA. Interestingly, QXPDA dictates the complete emission characteristics of the CNDs; in particular, it showed a striking similarity of its excitation independent emission spectra with that of the original synthesized red emissive CND solution. On the other hand, the CND like structure with a typical size of ∼4 nm was observed under a transmission electron microscope for a blue emissive species, which showed both excitation dependent and independent emission spectra. Interestingly, Raman spectroscopic data showed the similarity between QXPDA and the dot structure thus suggesting the formation of the QXPDA aggregated core structure in CNDs. We further demonstrated the parallelism in trends of absorption and emission of light from a few other red emissive CNDs, which were synthesized using different experimental conditions.Herein we unveil the presence of a molecular fluorophore quinoxalino[2,3-b]phenazine-2,3-diamine (QXPDA) in a colossal amount in red emissive CNDs synthesized from o-phenylenediamine, a well-known precursor molecule used for CND synthesis. 相似文献
798.
Sachin U. Sonavane 《Tetrahedron letters》2007,48(34):6048-6050
A one-pot, rapid and general method for the synthesis of symmetrical disulfides based on reaction of sulfur with sodium sulfide in the presence of didecyldimethylammonium bromide (DDAB) as a phase transfer catalyst is reported. Reaction with a variety of alkyl halides, at room temperature, afforded the disulfides in good to excellent isolated yields in a short time. 相似文献
799.
The enthalpy of formation at 298.15 K of the polymer Al13O4(OH)28(H2O)3+8 and an amorphous aluminium trihydroxide gel was studied using an original differential calorimetric method, already developed for adsorption experiments, and aluminium-27 NMR spectroscopy data. ΔHf “Al13” (298.15 K) = ? 602 ± 60.2 kJ mole?1 and ΔHf Al(OH)3 (298.15 K) = ? 51 ± 5 kJ mole?1. Using theoretical values of ΔGR “Al13” and ΔGR Al(OH)3, we calculated ΔGf “Al13” (298.15 K) = ? 13282 kJ mole?1; ΔSf “Al13” (298.15 K) = + 42.2 kJ mole?1; ΔGf Al(OH)3 (298.15 K) = ? 782.5 kJ mole?1; and ΔSf Al(OH)3 (298.15 K) = + 2.4 kJ mole?1. 相似文献
800.
Summary Clean and rapid analytical separation of microgram quantities of Ge(IV), Sn(II), Pb(II) and Zn(II), Cd(II), Hg(II) from their mixed solution has been made possible by ascending thin-layer chromatography using the solvent systems: (a)Isobutyl alcohol: Conc. HCl: Et-Me ketone and (b) Isobutyl alcohol: CH3COOH. For the evaluation of different metal ions, the resulting delineated spots as viewed in U.V. light were scooped out with the help of micro-vacuum cleaner and the collected material transferred to the paper set on the ring oven. Separate rings were obtained for individual metal ions and the computation of results having been made by ring colorimetry, using PTC and other chromogenic reagents.
Bestimmung von Ge(IV), Sn(II), Pb(II) und Zn(II), Cd(II), Hg(II) durch Ring-Colorimetrie nach Trennung durch Dünnschicht-Chromatographie
Détermination de Ge(IV), Sn(II), Pb(II) et de Zn(II), Cd(II), Hg(II) par colorimétrie annulaire après séparation par chromatographie sur couche mince相似文献