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991.
Structures of Ionic Di(arenesulfonyl)amides. 3. Four Sodium Di(arenesulfonyl)amides: Lamellar Layers Exhibiting Short C–H…O(nitro), C–H…F–C, or C–I…I–C Interlayer Contacts Low‐temperature X‐ray crystal structures are reported for NaN(SO2C6H4‐4‐X)2 · n H2O, where X = NO2 and n = 3 ( 1 , monoclinic, space group P21, Z = 2), X = F and n = 3 ( 2 , monoclinic, P21/c, Z = 4), X = F and n = 1 ( 3 , orthorhombic, Pccn, Z = 8), or X = I and n = 1 ( 4 , monoclinic, P21/c, Z = 4). The four compounds are examples of layered inorgano‐organic solids where the inorganic component is comprised of metal cations, N(SO2)2 groups and H2O molecules and the outer regions are formed by the 4‐substituted phenyl rings of the folded anions. In the two‐dimensional coordination networks, the cations adopt either an octahedral [Na(O–S)2(OH2)4] ( 1 , 2 ) or a distorted monocapped octahedral [NaN(O–S)4(OH2)2] ( 3 , 4 ) environment. Taking into account the differing crystal symmetries within the two pairs of compounds, it is remarkable that the trihydrates 1 / 2 and the monohydrates 3 / 4 each display chemically identical and nearly isometric Na–O or Na–O/N networks. In the crystal packings, parallel layers are connected through weak hydrogen bonds C–H…O(nitro) ( 1 ) or C–H…F ( 2 , 3 ), or through short “type I” I…I contacts ( 4 ). There is good evidence that the strikingly distinct crystal symmetries in the halogenated homologues 3 / 4 are determined by the specific complementarity requirements of the interlayer binding centres. 相似文献
992.
993.
L. Jones Tarcius Doss A. K. Pani S. Padhy 《Numerical Methods for Partial Differential Equations》1997,13(4):393-416
Based on a Landau-type transformation, both continuous and discrete in time L2-Galerkin methods are applied to a single-phase Stefan-type problem in one space dimension. Optimal rates of convergence in Lℵ, L∞, and H1-norms are derived and computational results are presented. © 1997 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 13: 393–416, 1997 相似文献
994.
Harald Grger Davoud Tehranfar Jürgen Martens Jens R. Goerlich Holger Thnnessen Peter G. Jones Reinhard Schmutzler 《Heteroatom Chemistry》1997,8(3):207-215
The addition of dimethylphosphine oxide and its trimethylsiloxyphosphorus(III) derivative, generated in situ, to 3-thiazolines was found to yield dimethyl 4-thiazolidinylphosphine oxides via three different synthetic routes. The structures of two products were confirmed by X-ray analysis; common features include approximate envelope conformations of the five-membered rings and hydrogen bonding of the form N–H· · ·O=P. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8 : 207–215, 1997. 相似文献
995.
996.
E. D. T. Atkins M. J. Hill N. A. Jones S. J. Cooper 《Journal of Polymer Science.Polymer Physics》1998,36(13):2401-2412
Chain-folded lamellar crystals of nylon 2 4 have been prepared from dilute solution by addition of poor solvent. Two crystal structures are observed at room temperature: a monoclinic form I, precipitated at elevated temperature, and a less-defined, orthorhombic form II, precipitated at room temperature. The unit cell parameters for both forms are similar to those reported for its isomer, nylon 3. Nylon 2 4 form II is a liquid–crystal-like or disordered phase, consisting of hydrogen-bonded sheets in poor register in the hydrogen bond direction. Form I crystals have two characteristic interchain spacings of 0.41 nm and 0.39 nm at room temperature and on heating, exhibit a structural transformation and a Brill temperature (250°C) characteristic of many other even–even nylons. Nylon 2 4 is a member of the nylon 2 Y and nylon 2N 2(N+1) families, and the form I crystals show behavior commensurate with both. We propose they contain a proportion of intersheet hydrogen bonds at room temperature, similar to that for the nylon 2 Y family, and the short dimethylene alkane segments mean that the structure consists of hydrogen-bonded a-sheets, with an amide unit in each fold, similar to that of nylon 4 6. The fold geometry and sheet structure is compared with chain-folded apβ-sheet polypeptides and nylon 3. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2401–2412, 1998 相似文献
997.
M. Carmen Blanco Eduardo J. Fernndez Peter G. Jones Antonio Laguna Jos M. Lpez-de-Luzuriaga M. Elena Olmos 《Angewandte Chemie (International ed. in English)》1998,37(21):3042-3043
The covalent radius of Au I is about 0.07 Å smaller than that of AgI. This was determined from the crystal structures of the isostructural complexes [N(PPh3)][{Au(C6F5)3(μ-PPh2)}2M] (M=Au (structure shown in the picture), Ag). These mixed AuIII–M phosphides were synthesized from [Au(C6F5)3(PPh2H)], the first gold complex to contain a secondary phosphane. 相似文献
998.
Polysulfonylamines. XCIV. Molecules with Unusually Long N(sp2)–Si(sp3) Bonds: Synthesis and Crystal Structures of 1,2-Benzenedisulfonylaminosilanes The following compounds were obtained by metathesis of silver 1,2-benzenedisulfonimide (AgZ) with the appropriate chlorosilanes: ZSiMe3 ( 4 ), ZSinPr3, ZSiMe2nBu, ZSiMe2(CMe2–CHMe2) ( 7 ), (Z)2SiMe2 ( 8 ). In the crystal structures of 4 (monoclinic, space group P21/n), 7 (monoclinic, P21/c) and 8 (monoclinic, P21/n), which were determined by low-temperature X-ray diffraction, the molecules adopt the N-silyl form and display unusually long bonds between the trigonal-planar N and the tetrahedrally coordinated Si atoms ( 4 : 182.6, 7 : 184.1, 8 : 177.8 and 180.5 pm). For 7 in CDCl3 solution, 1H and 13C NMR data indicate N,O-silylotropy. The solid state structures of molecules 4 and 7 strongly suggest that the N–Si bond lengthening in N,N-disulfonylated aminosilanes is mainly induced by the π-acceptor character of the SO2 groups and not by the occasionally observed coordination expansion of the Si atom through short intramolecular O…Si contacts. 相似文献
999.
By reaction of N-(N′,N′,N″,N″-tetramethyl)guanidinyl-substituted phosphines with diorganochlorophosphines, organodichlorophosphines, p-tolylsulfenylchloride and phenylselenylchloride a variety of stable phosphonium chlorides with a P–E (E = P, S, Se) bond were obtained. In one case, performing this reaction in the presence of sodium tetraphenylborate led to the corresponding phosphonium tetraphenylborate. All compounds were characterised by multinuclear NMR and elemental analysis. The selenophosphonium chloride 4 a of the trihydrate was further characterised by a single crystal X-ray analysis. The P–Se bond is very long [193.0(3), 193.3(3) pm in two independent fomula units]. The water molecules and the chloride anions form hydrogen bonded layers. 相似文献
1000.
Jens Mahnke Andreas Zanin Wolf-Walther du
Mont Frank Ruthe Peter G. Jones 《无机化学与普通化学杂志》1998,624(9):1447-1454
The New P -Phosphanylphosphaalkene 1-Bis(trimethylsilyl)methylidene-2,2-diisopropyldiphosphane: First Reactions at its P=C and P–P Bonds (Me3Si)2C=PCl ( 1 ) reacts with the trichlorosilylphosphanes RR′PSiCl3 (R and R′ = t-Bu or i-Pr) providing the new P-dialkylphosphanylphosphaalkenes (Me3Si)2C=P–P-i-Pr2 ( 2 ) and (Me3Si)2C=P–P(t-Bu)(i-Pr) ( 3 ) as well as the known (Me3Si)2C=P–P-t-Bu2 ( 4 ). The P=C double bond of 2 can be protected reversibly by a [2 + 4]-cycloaddition with cyclopentadiene resulting in the formation of a P-phosphanyl-phosphanorbornene derivative 5 . The [2 + 4]-cycloaddition of 2 with 2,3-dimethylbutadiene provides the cyclic diphosphane 6 . Reactions of 2 with sulfur and selenium were followed by 31P and 77Se nmr: Chalcogen insertion into the P–P bond leads to the products (Me3Si)2C=P–X–P-i-Pr2 9 a (X = S) and 9 b (X = Se). Subsequent σ3λ3 → σ4λ5 oxidation steps of 9 a with S and of 9 b with Se lead to compounds (Me3Si)2C=P–X–P(=X)-i-Pr2 10 a (X = S) and 10 b (X = Se), which contain phosphinic acid functions with the phosphaalkene moieties attached to S or Se. 10 a and 10 b were not isolated in a pure state. However, trapping 10 b from an enriched solution by [2 + 4]-cycloaddition with cyclopentadiene allowed the isolation of the P-diseleno-phosphinato-phosphanorbornene 12 . The constitution of new compounds 2 , 3 , 5 , 6 and 12 was confirmed by elemental analyses, nmr and mass spectra. The structures of cycloadducts 5 and 6 were determined by X-ray diffraction analysis. 相似文献