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991.
适合低PH范围测量的新型中性载体膜PH电极的研究 总被引:2,自引:0,他引:2
本文设计合成了一种在低PH范围对氢离子有很好Nernst响应的新型中性载体-N,N-二辛基菸酰胺,并把它制成PVC膜PH电极,测试了该电极的线性范围、选择性、稳定、重现性和内阻等各项性能参数,并试验了电极抗氢氟酸腐蚀的能力,该该电极用于氢氟酸的电离常数测定时获得了满意的结果。 相似文献
992.
Protein dynamics are the key to understanding their behavior. The static protein structure alone in most cases is insufficient to describe the vast array of complex functions they perform in vivo. Until recently there were relatively few techniques available to investigate the dynamic nature of these proteins. Mass spectrometry has recently emerged as a powerful biophysical method, capable of providing both structural and dynamic information. By utilizing the labile nature of amide hydrogens as a marker of the backbone dynamics in solution, combined with gas-phase dissociation techniques, we now have a high-resolution tool to locate these exchanging hydrogens within the sequence of the protein and to probe the functional importance of its structural elements. In this paper we describe several applications of these methodologies to illustrate the importance of dynamics to the biological functions of proteins. 相似文献
993.
聚合物 /无机纳米复合材料是当今材料研究中的热点。但由于无机纳米颗粒在聚合物中不易分散 ,有时用具有纳米层间距的片晶结构的无机矿物 ,如蒙脱土作填料 ,通过聚合时的热效应来撑开片晶达到蒙脱土的纳米级分散 ,制得所谓的插层聚合物〔1〕。插层型纳米复合材料不仅物理力学性能有很大提高 ,并且也为高分子凝聚态物理工作者提供了研究聚合物分子在二维空间受限情况的理想模型。由于在蒙脱土层间和层外的聚合物所处的环境不一样 ,它们的一些行为会有所不同。本文在用动态扭振法研究环氧树脂 /蒙脱土插层聚合物的等温固化行为时 ,观察到了该… 相似文献
994.
Shinji Watanabe Masaru Tanabe Mitsutoshi Jikei Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1995,33(14):2385-2391
New ethynylene-containing aromatic polymides were synthesized by the carbon–carbon crosscoupling polycondensation of aromatic diiodides with aromatic amide-bearing diethynyl compounds in the presence of a palladium catalyst, cuprous iodide, and an organic base. The polymers having sulfone linkages were soluble in various organic solvents and their weight average molecular weights were in the range of 12,500 and 26,500. The polymers with the highest inherent viscosity were obtained, when the monomer ratio of a diethynyl compound to a diiodide was 1.01. The polymers showed no detectable glass transition temperature and no weight loss up to around 300° C in nitrogen. The thermal crosslinking of the polymers occurred at 280°C through the existing internal ethynylene group. © 1995 John Wiley & Sons, Inc. 相似文献
995.
Polysulfonyl Amines. LXXII. Triphenylcarbenium and Triphenylphosphonium Di(fluorosulfonyl)amides: Two Crystal Structures with Ordered (FSO2)2N? Sites Treatment of HN(SO2F)2 in CH2Cl2 with Ph3P, Ph3PO or collidine (=B) affords the compounds Ph3PH⊕[(FSO2)2N]? ( 3 ), Ph3PO · HN(SO2F)2, and BH⊕[(FSO2)2N]? ( 7 ). The carbenium salt Ph3C⊕[(FSO2)2N]? ( 5 ), obtained by metathesis of Ph3CBr with [(C6H6)AgN(SO2F)2] in CH2Cl2, crystallizes from chloroform/petroleum ether as a monosolvate Ph3C⊕[(FSO2)2N]? · CHCl3 ( 6 ). In presence of a sterically hindered base, viz. collidine, 5 is a suitable reagent for the tritylation of molecules containing weakly activated H atoms (e. g.: MeCN → Ph3CCH2CN, acetone → tritylacetone; co-product: 7 ). The crystal structures of the ionic solids 3 (monoclinic, space group P21/n) and 6 (monoclinic, P21/c) were determined by X-ray diffraction at ?130°C; the structure refinements were not impaired by the notorious tendency of the (FSO2)2N moiety towards crystallographic disorder. As in the known structure of the tetraphenylarsonium salt, the anion of 3 and 6 adopts a staggered conformation of approximately C2 symmetry (averages of all values: S? N? S 121.4°, N? S 156.2, S? O 141.6, S? F 156.6 pm). The crystal packing of 6 displays a three-centre C? H(…?O)2 hydrogen bond between the CHCl3 molecule and two oxygen atoms of a single anion, resulting in a six-membered ring [R12(6) pattern; H …? O 234 and 262 pm]. The crystal of 3 contains one-dimensional arrays of alternating cations and anions connected by a three-centre P? H(…?O)2 bond [C(6) pattern; H …? O 237 and 254 pm]. The Ph3C⊕ cation of 6 is propeller-shaped, with three coplanar central bonds (mean C? C 144.5 pm) and interplanar angles of 52.7, 56.4 and 60.1° between the phenyl groups. 相似文献
996.
聚酰胺酰亚胺 (PAI)是一类已商业化的耐热高分子材料 ,具有与聚酰亚胺类似的耐热性能 ,但是改善了聚酰亚胺的溶解性、可加工性能 ,因此进一步开发综合性能优异、加工性能好的聚芳酰胺酰亚胺近年来成为研究热点之一[1~ 3 ] .PAI的经典制备方法为 :( 1 )偏苯三酸酰氯与芳香二胺的聚合反应 ;( 2 )含酰亚胺环的偏苯酸和异氰酸酯反应 .近年来聚酰胺酰亚胺又开发了以下途径制备 :( 1 )含亚胺环的二酸与芳香二胺一步缩聚反应 ;( 2 )含亚胺环的芳香二卤代物与二胺的催化羰基化反应等[4~ 6] .本研究组近期合成了一种新型芳香二胺 ,并合成了耐… 相似文献
997.
The interactions between nonionic surfactants such as polyoxyethylene cetyl ethers (C16EO20) and the polymer gelatin were investigated by rheological methods. Capillary viscosity measurements of diluted aqueous solutions confirmed the results of previous investigations [1]. C16EO20 caused an accelerated renaturation of the polypeptide gelatin.A strong variation of viscoelastic data was measured by vibration rheometry when gelatin was added to the lyotropic cubic liquid crystalline phases formed by the surfactant used. Loss module (E) and loss factor (tan ) increased with increasing content of the polymer indicating an obstruction of the coupling between the globular surfactant associates. 相似文献
998.
Takeshi Shimizu Junichi KusakaHaruaki Ishiyama Tadashi Nakata 《Tetrahedron letters》2003,44(27):4965-4968
The 6,6-spiroacetal segment of spirofungin A, an antifungal antibiotic isolated from Streptomyces violaceusniger Tü 4113, was efficiently prepared via the coupling reaction of the Weinreb amide and the alkyne which are readily available from the common intermediate. The synthesis includes the unsymmetrization through a stereoinversion at the C11 position and the transacetalization as the key steps. 相似文献
999.
The solid state thermal behavior of trans-[Co(bpb)(amine)2]NCS⋅H2O complexes where (bpb)=[N,N’-bis(2-pyridinecarboxamido-N)-1,2-benzene], and amine=pyrrolidine (prldn)(1), and benzylamine (bzlan) (2), and trans-[Co(bpb)(piperidine)2]ClO4⋅H2O (3) (mixed with KSCN), has been studied using thermoanalytical techniques, infrared spectroscopy, and pyrolysis coupled
to both infrared and mass spectrometry, PY/FTIR and PY/MS. The deamination-anation reaction is clearly observed for all three
complexes. The estimated values of E
a for the deamination-anation are: E
a(1)=246.8 kJ mol−1, E
a(2)=255.7 kJ mol−1, E
a(3)=234.7 kJmol−1. The trend in E
a values is rationalized based on the ligand field strength of the amines and the structural effects. A novel decarbonylation
of the amide CO group from the equatorial ligand is observed after the release of one amine molecule. This process has been
monitored for complex (1) by FTIR in the carbonyl region and by mass spectrometry for the detection of CO2 at 280°C. The activation energy of this process is estimated for complex (1) (662.5 kJ mol−1). The reaction scheme for the observed reactions is proposed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
1000.
M. P. Pasechnik I. M. Aladzheva E. I. Matrosov A. P. Pisarevskii Yu. T. Struchkov T. A. Mastryukova M. I. Kabachnik 《Russian Chemical Bulletin》1994,43(4):660-665
The crystalline complex [Ag(L
1)NO3]2 (A) was isolated by the interaction of (N,N-diethylcaibamoylmethyl)diphenylphosphine sulfide Ph2P(S)CH2C(O)NEt2 (L
1) with AgNO3 in different solvents at the ratios of metal:ligand = 11 and 12. According to the X-ray data, complexA is a center-symmetric dimer with bridge sulfur atoms. The cations of the metal are in a tetrahedral environment formed by two S atoms and the O atoms of CO and NO3 groups. The interaction ofL
1 with AgNO3 was studied in solution by IR spectroscopy, and the structures of the complexes formed are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 708–713, April, 1994.The authors are grateful to B. V. Lokshin and his coworkers for help in measurement of the Raman spectra and for useful discussion.The present investigation was financially supported by the Russian Foundation for Basic Research (Project 93-03-4351). 相似文献