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991.
L. I. Demina L. G. Kuz’mina S. V. Demin N. A. Shokurova V. I. Zhilov A. Yu. Tsivadze 《Russian Journal of Inorganic Chemistry》2017,62(11):1536-1543
The complex formation of lithium with benzo-15-crown-5 (B15C5) was investigated. The complexes LiB15C5H2OX, where X = Cl? (1), I? (2), (3), (5), and LiBF4B15C5 (4) were synthesized and studied by IR spectroscopy. Complexes 1–4 were examined by X-ray diffraction. According to IR spectroscopy data, the crown ether conformation changes upon dissolution. The interaction of the extracted complex with the solvent was identified. 相似文献
992.
L. S. Skogareva S. Yu. Kottsov T. O. Shekunova A. E. Baranchikov O. S. Ivanova A. D. Yapryntsev V. K. Ivanov 《Russian Journal of Inorganic Chemistry》2017,62(9):1141-1146
It has been shown for the first time that the use of hydrogen peroxide allows precipitation of rare earth orthophosphates (La–Tb) from phosphoric acid solutions at temperatures below 100°C. Either anhydrous or hydrated orthophosphates with monazite or rhabdophane structure, respectively, can be obtained depending on rare earth element position in lanthanide series and precipitation conditions (orthophosphoric acid and hydrogen peroxide concentration). Hydrated orthophosphates with rhabdophane structure can be prepared by precipitation with hydrogen peroxide for all studied rare earth elements. 相似文献
993.
M. O. Agafonkina N. P. Andreeva Yu. I. Kuznetsov S. F. Timashev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(8):1414-1421
The adsorption of substituted 1,2,3-benzotriazoles (R-BTAs) onto copper is measured via ellipsometry in a pure borate buffer (pH 7.4) and satisfactorily described by Temkin’s isotherm. The adsorption free energy (?ΔG a 0 ) values of these azoles are determined. The (?ΔG a 0 ) values are found to rise as their hydrophobicity, characterized by the logarithm of the partition coefficient of a substituted BTA in a model octanol–water system (logP), grows. The minimum concentration sufficient for the spontaneous passivation of copper (C min) and a shift in the potential of local copper depassivation with chlorides (E pt) after an azole is added to the solution (i.e., ΔE = E pt in ? E pt backgr characterizing the ability of its adsorption to stabilize passivation) are determined in the same solution containing a corrosion additive (0.01М NaCl) for each azole under study. Both criteria of the passivating properties of azoles (logC min and ΔE) are shown to correlate linearly with logP, testifying to the role played by surface activity of this family of organic inhibitors in protecting copper in an aqueous solution. 相似文献
994.
E. Yu. Tyulyaeva N. G. Bichan T. N. Lomova A. S. Semeikin 《Russian Journal of Inorganic Chemistry》2017,62(12):1576-1583
The spectral (UV–Vis, IR, and NMR 1H) properties and the state of oxorhenium(V) complexes with 5,15-bis(4′-methoxyphenyl)-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphin H2P (O=Re(X)P) in protic solvents have been studied depending on the axial trans-ligand X– (X = Cl, OPh, or OH). The O=Re(Cl)P, O=Re(OPh)P, and O=Re(OH)P in AcOH and CF3COOH are subjected to reaction of substitution their axial ligands with solvent molecules or anions, while remaining stable to the dissociation of M–N bonds and to oxidation both to the macrocyclic ligand and to the central metal cation. Quantitative parameters of the coordination of molecular oxygen by O=Re(Cl)P in 17.4–18.2 M H2SO4 to form O=Re(O2)P+ · Cl– have been obtained, these parameters being independent of the initial H2SO4 concentration. The character of peripheral functional substituents in H2P has been shown to be responsible for the stability of the studied oxo complexes to chemical oxidation in aerated acids. 相似文献
995.
Bing Liang Shujuan Yu Jie Li Fan Wang Gaolin Liang Ao Zhang Chunyong Ding 《Tetrahedron letters》2017,58(19):1822-1825
A novel catalyst-free Csp3-H aryloxylation approach allowing for rapid installation of a wide range of aryloxyl groups regioselectively at the C-4 position of Tanshinone IIA under simple and mild conditions was developed. This unique protocol exhibited atom-/step-economy, low cost, high efficiency and robust functional-group tolerance, which will greatly facilitate to diversify the A-ring of the bioactive natural product. 相似文献
996.
A metal-free protocol for the selective cleavage of unstrained C–C single bonds was developed. Under the catalysis of KI and in the presence of NaHCO3, the readily available α-chloro-β-hydroxy ketones underwent bond breaking and sulfonylation smoothly to afford β-ketosulfones with high efficiency and broad substrate scope. Mechanism investigations, both experimental and theoretical, showed that a retro-aldol cleavage/nucleophilic substitution sequence might be involved. 相似文献
997.
Wei Cheng Ming Ji Xiaodan Li Jinwei Ren Fuling Yin Leen van Ofwegen Siwang Yu Xiaoguang Chen Wenhan Lin 《Tetrahedron》2017,73(17):2518-2528
Chemical investigation of the gorgonian coral Junceella fragilis resulted in the isolation of a new norditerpenoid fragilolide A (1), sixteen new briarane diterpenoids fragilolides B-Q (2–17), together with frajunolides H and N, and three known norcembranoids scabrolide D, sinuleptolide and 5-epi-sinuleptolide. The structures of new compounds were determined on the basis of extensive spectroscopic analysis, including the experimental and calculated ECD data and single-crystal X-ray diffraction for the configurational assignments. The structure of fragilolide A featured an unprecedented 4,13- and 7,11-fused tetracyclic norcembranoid, while the biogenetic relationships of the briarane analogues were postulated. Frajunolide H exerted significant inhibition against a panel of tumor cell lines, and six briarane diterpenoids (3, 6, 8, 12, 16, and frajunolide N) exhibited the inhibitory effects against the HBeAg express of hepatitis B virus in HepAD38 cells. In addition, sinuleptolide and 5-epi-sinuleptolide exerted the effects to inhibit NO production in RAW264.7 macrophage cells, in addition to the activation of ARE and the inhibition of NF-κB expression. 相似文献
998.
V. V. Sergeev Yu. V. Kos 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(11):2131-2136
The saturated vapor pressure over solutions of methacrylic acid is measured tensimetrically in acetonitrile, benzene, hexane, 1,2-dichloroethane, and acetic acid is measured tensimetrically at 290–350 K. The composition of equilibrium phases, the activity coefficients of the components, and the thermodynamic functions of the mixing (H E , G E , S E ) of the investigated solutions are calculated from the temperature dependence data. 相似文献
999.
A. Yu. Vasil’kov D. A. Migulin A. V. Naumkin Ya. V. Zubavichus A. V. Budnikov O. G. Ellert Yu. V. Maksimov A. M. Muzafarov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(11):2188-2194
New hybrid materials based on Pt, Fe, and Pt–Fe nanoparticles stabilized in a matrix of polymethylsilsesquioxane nanogel and ultrahigh molecular weight polyethylene (UHMWPE) were prepared. Metal vapor synthesis was used to produce mono- and bimetallic nanoparticles. It was shown that organosilicon nanogel effectively stabilizes Pt nanoparticles with an average size of 0.9 nm. Using the nanogel results in the formation of superparamagnetic Fe particles 3–5 nm in size that consist of ferromagnetic Fe0 core and antiferromagnetic shells of Fe oxides. It is established that using an organosilicon matrix in the formation of Pt-Fe/UHMWPE systems helps reduce the average particle size of Fe in the material from 6.5 to 4.5 nm and narrow their particle size distribution. The composition, magnetic and electronic characteristics of the nanocomposites are studied via transmission electron microscopy, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, XANES, and EXAFS. 相似文献
1000.
J. M. Ashurov L. Yu. Izotova B. T. Ibragimov N. S. Mukhamedov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(1):106-110
Two crystalline polymorphic forms of α-(N-benzoxazolin-2-one)acetic acid (BAA) are prepared by changing the temperature of its crystallization from solution in ethanol. Crystallographic data of the α-form are determined: a = 12.7769(17) Å, b = 8.2574(9) Å, c = 16.7390(19) Å, β = 105.087(13)°, space group C2/c, V = 1705.2(4) Å3, and Z = 8, while those of β form are a = 5.2854(4) Å, b = 5.9880(4) Å, c = 13.4509(5) Å, β = 94.666(4)°, space group P21, V = 424.30(4) Å3, and Z = 2. It is found that BAA molecules of the α form combine into infinite one-dimensional chains arranged along axis b by means of O?H···O and C?H···O hydrogen bonds, and these chains are crosslinked via C?H···O hydrogen bonds to form a threedimensional structure. The β form has another system of hydrogen bonds, one of which is bifurcated (O4···O2, O4···O3), and the π–π-interactions between the benzoxazolinone fragments of BAA molecules combined into a chain also arranged along axis b are observed. Calorimetric analysis shows that the polymorphic transition from the α form to the β form occurs at 129°C. 相似文献