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921.
Tulyasheva M Rasulev BF Tojiboev AG Turgunov KK Tashkhodjaev B Abdullaev ND Shakhidoyatov KM 《Molecules (Basel, Switzerland)》2005,10(9):1209-1217
The new compounds (Z)-ethyl 2-cyano-2-(3H- and 2-methyl-3H-quinazoline-4-ylidene) acetate (1 and 2, respectively) were synthesized by multi-step reactions. The structures in a solution have been determined by (1)H-NMR spectroscopy and in the crystal form by X-ray analysis. Molecule 1 crystallized in a primitive monoclinic cell, space group capital ER, P2(1/c). The cell dimensions are a=7.970(6) A, b=7.061(2) A, c=20.537(7) A, beta=97.69(5) degrees , V=1145.3(10) A(3). Molecule 2 crystallized in a triclinic cell, space group P-1, the cell dimensions are a=8.196(5) A, b=8.997(6) A, c=9.435(4) A, alpha=74.22(4) degrees, beta=89.75(4) degrees , gamma=74.07(5) degrees , V=641.9(6) A(3). In both compounds the presence of intra-molecular NH---O=C hydrogen bonding between the nitrogen atom in position 3 of the quinazoline ring and a carbonyl group of the ethyl cyanoacetate residue was proven by quantum-chemical, (1)H-NMR and X-ray methods. 相似文献
922.
Synthesis and X-Ray Structure Analysis of the 8π-Electron-Ring-System S4N4O2Sn2(CH3)6 and the Magnetic Properties of S4N4O2 and S8N8O4 S4N4O2 reacts with N[Sn(CH3)3]3 in a molar ratio of 1:1 to an eight-membered trimethyltin-substituted 8π-electron skeleton, S4N4O2Sn2(CH3)6. In contrast to known 6π-electronsystems this compound has tin atoms which are tetracoordinated. This was demonstrated on the basis of an x-ray analysis. S4N4O2Sn2(CH3)6 · 1/2 C6H6 crystallizes in the space group P21/c with a = 1396.0(4), b = 1190.3(4), c = 1256.7(3) pm, and β = 103.46(2)°. It was shown that the ability of coordination at the tin atom depends on the electron density. The magnetic properties of S4N4O2 and S8N8O4 were investigated by the Faraday method. The high diamagnetism in these ring compounds is caused by the π-electrons. 相似文献
923.
Abstract— The thiopyronin-sensitized photooxidation of guanosine was investigated, using flash photolysis techniques. The reaction kinetics of three short-lived intermediates (the triplet state, the reduced radical, and the oxidized radical) were followed by spectroscopy. The influence of guanosine concentration on the reaction rate shows that only the oxidized radical (reaction 7) of thiopyronin is affected by guanosine. This suggests that the primary step in the photodynamic destruction of DNA is the oxidation of guanosine by the oxidized radical of thiopyronin (reaction 9). This mechanism is discussed in terms of the redox potentials of the donor and the acceptor for three different cases: (1) where the oxidation potential of the donor is more negative than that of the triplet state, the acceptor being the triplet state ( FT ); (2) where the oxidation potential of the donor is between the potentials of the triplet state and the oxidized radical, the acceptor being the oxidized radical (Fox ); and (3) where the oxidation potential of the donor is more positive than the reduction potential of both the triplet state and the oxidized radical; in this case no electron exchange takes place. The thiopyronin-guanosine system is an example of the second case. 相似文献
924.
F. P. Sidel'kovskaya V. A. Ponomarenko M. G. Zelenskaya A. V. Ignatenko O. D. Trifonova É. A. Abdula-Zade A. G. Kechina L. A. Sinitsyna 《Russian Chemical Bulletin》1976,25(3):587-593
1. | Some new -oxides were synthesized, which contain a lactam ring in the substituent and have the general structure: where R = H, CH3; OC OC2H5, and Z = CH2, CH2OCH2, (CH2)2OCH2. |
2. | It was shown on the example of the synthesized glycidyl ethers that they are capable of forming polymeric products under the influence of nucleophilic agents, and also of adding water, ammonia, and diethylamine under mild conditions. |
925.
Zusammenfassung Bei Einwirkung von H2S und Aminen bzw. NH3 auf Acetophenon bzw. Propiophenon entstehen in Gegenwart elementaren Schwefels Bis-[1-phenylalkyl-(1)]-polysulfide, ohne Zusatz von Schwefel in der Hauptsache Bis-[1-phenylalkyl-(1)-]-disulfide. Die Struktur der linearen Di- und Polysulfide wurde durch Chlorolyse und Vergleich mit auf anderem Wege hergestellten Polysulfiden ermittelt.Die Reaktionen verlaufen über Ketimine als Zwischenstufe. Diese Intermediärprodukte wurden synthetisiert und geben bei der H2S-Behandlung gleichfalls Bis-[1-phenylalkyl-(1)]-disulfide. Die Frage des Auftretens von Enaminen bei Verwendung von Morpholin als Aminkomponente wird diskutiert.Teil der Dissertation vonK. Halcour, T. H. Aachen, 1961. 相似文献
926.
A. P. Kilimov M. A. Svechnikova V. I. Shevchenko V. V. Smirnov F. V. Kvasnyuk-Mudryi S. B. Zotov 《Chemistry of Heterocyclic Compounds》1967,3(2):467-471
Data for the characteristic bands of cyclic ethers are reviewed. The infrared spectra of a number of 2-mono- and 2, 5-di-substituted
derivatives of tetrahydrofuran are investigated. Absorption bands at about 900 cm−1 are related to pulsation vibrations, and those at about 1200 cm−1 to antisymmetric skeletal vibrations, of the tetrahydrofuran ring. It is shown that to confirm the presence of a tetrahydrofuran
ring in a molecule, it is necessary to take into account not only the band of valence antisymmetric vibrations of the group
C-O-C (ν
C-O-C
as
1075 cm−1), but also bands due to ring pulsation vibrations (ring symmetric valence vibrations ν
sk
s
∼ 900 cm1). 相似文献
927.
The effect of substituted hydroxybenzophenone, benzotriazole and organic metal complexes on the photooxidation of PP films has been studied. It has been established that NiDBTC added in 1.0 wt. % is the most effective photostabilizer.While in the case of other stabilizers there is a slight increase in the Co content even during the induction period, with the application of NiDBTC practically no oxidation can be observed before the stabilizer completely disappears. This means that NiDBTC inhibits the photooxidation of the polymer even in low concentration.
, - . , Ni, 1,0 . %. . , Ni , . , Ni .相似文献
928.
Rh(π-C3H5)(PF3)3 (I), reacts with trifluoroacetic acid to form propene and [Rh(CF3COO)(PF3)2]2 (II). I reacts with t-butyl bromide to give [RhBr(PF3)2]2 and a mixture of propene and 2-methyl-1-propene and with n-propyl bromide to give propene and [RhBr(PF3)2]2. Rh(π-C3H5)(PPh3)2 (III), and t-butyl bromide yield propene and 2-methyl-1-propene. In these reactions a mechanism involving β-hydrogen abstraction and hydrogen migration via the metal to carbon is proposed. When III reacts with Me3SnCl the Me3Sn—moiety migrates intact to the π-allyl group. I reacts with acetyl chloride to give propene, [RhCl(PF3)2]2 and the carbonyl rhodium complex Rh2Cl2(PF3)3(CO). II does not apparently undergo phosphine ligand exchange unlike the analogous halogeno-bridged dimers. 相似文献
929.
The optically active methylphenyl-α-naphthylsilane racemises quickly in tetrahydrofuran in the presence of LiAlH4.Kinetic results show a different behaviour of the hydride depending on its concentration. Activation parameters have been obtained and mechanisms proposed. 相似文献
930.
. .
Air regeneration of a coked silica-alumina catalyst for the synthesis of pyridines and picolines has been studied. The results are discussed in relation to changes in porosity and structure occuring during thermal treatment.相似文献