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961.
R.G.?Song M.?Yamaguchi O.?Nishimura K.?Shimokawa N.?Kushibiki M.?SuzukiEmail author 《Applied Physics A: Materials Science & Processing》2004,78(6):867-875
We have studied the effect of copper nanoparticles produced by laser ablation on the ring-opening polymerization of 1,1,3,3-tetraphenyl-1,3-disilacyclobutane (TPDC). The particle size and distribution of laser-ablated, copper nanoparticles were controlled by laser-ablation conditions such as ambient pressure, laser fluence, and distance between target and substrate. Laser-ablated, copper nanoparticles induced polymerization of TPDC effectively, resulting in formation of poly(diphenylsilylenemethylene) (PDPhSM) thin films. The polymerization efficiency depended mainly on the particle size and the surface concentration of copper nanoparticles deposited on the TPDC films by laser ablation. No clear tendency was observed between oxidation of Cu nanoparticles and polymerization efficiency. This technique enables us to easily fabricate PDPhSM thin films and may become a new method for fabricating polymer–metal nanocomposites. PACS 81.05.Lg; 82.35.Np; 82.50.Hp 相似文献
962.
Ochiai M Miyamoto K Shiro M Ozawa T Yamaguchi K 《Journal of the American Chemical Society》2003,125(43):13006-13007
The isolation, characterization, and reaction of the active species hydroxy(phenyl)iodonium ion with hypervalent bonding are reported. Reaction of iodosylbenzene with HBF(4)-Me(2)O in the presence of equimolar 18-crown-6 in dichloromethane afforded the hydroxy-lambda(3)-iodane complex PhI(OH)BF(4).18-crown-6 as stable yellow prisms. X-ray structure analysis indicated that both the close contacts between the iodine(III) and the three adjacent oxygen atoms of 18-crown-6, and the hydrogen bonding OH.O(crown ether) will be responsible for the increased stability of the complex as compared to the uncomplexed PhI(OH)BF(4). The crown ether complex is highly reactive and serves as a versatile oxidant even in water: thus, the complex undergoes oxidative transformations of a variety of functional groups such as olefins, alkynes, enones, silyl enol ethers, sulfides, and phenols under mild conditions. 相似文献
963.
Konno T Haneishi K Hirotsu M Yamaguchi T Ito T Yoshimura T 《Journal of the American Chemical Society》2003,125(31):9244-9245
Treatment of fac(S)-[Rh(aet)3] (aet = 2-aminoethanethiolate) with aqueous HBF4 in air led to the protonation at coordinated thiolato groups to give a rhodium(III) dimer, [{Rh(aet)2(Haet)}{Rh(aet)(Haet)2}](BF4)3 ([1](BF4)3). On the other hand, similar treatment of fac(Se)-[Rh(aes)3] (aes = 2-aminoethaneselenolate) produced a dinuclear rhodium(III) complex, [Rh2(selenocystamine)3](BF4)6 ([2](BF4)6), because of the autoxidation of coordinated selenolato groups by air. The crystal structures of [1](BF4)3, DeltaDelta-[1](BF4)3, and [2](BF4)6 were determined by X-ray crystallography. In [1]3+ two RhIII octahedrons are connected through a strong triple thiol-thiolate S-H...S hydrogen bond, while two RhIII octahedrons are directly joined by a triple diselenide bond in [2]6+. The cyclic voltammetry indicated that in acidic media the RhIII center in fac(Se)-[Rh(aes)3] is more easily oxidized to RhIV than that in fac(S)-[Rh(aet)3], which is responsible for the formation of coordinated diselenide bonds. 相似文献
964.
3+3]Cycloalkyne dimers linked by an azo group: a stable cis-azo compound forms polymeric aggregates by nonplanar pi-pi interactions 总被引:1,自引:0,他引:1
Saiki Y Sugiura H Nakamura K Yamaguchi M Hoshi T Anzai J 《Journal of the American Chemical Society》2003,125(31):9268-9269
We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV-vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene structure isomerizes readily. 相似文献
965.
Fukami T Yamaguchi K Tozuka Y Moribe K Oguchi T Yamamoto K 《Chemical & pharmaceutical bulletin》2003,51(2):227-229
The crystal structure of inclusion complex between ursodeoxycholic acid (UDCA), and phenanthrene has been determined. UDCA molecules formed hydrogen bond network to provide the channel structure along b axis, and phenanthrene molecules were accommodated in the cavity with a stoichiometry of 1 : 1 molar ratio. The channel structure observed in the UDCA-phenanthrene complex was significantly different from that of inclusion complex previously reported for deoxycholic acid (DCA) and cholic acid (CA). Because of the mesh-like hydrogen bond network, channel framework of UDCA could have less flexibility than that of DCA and CA. The difference of molecular state of phenanthrene was clearly observed in solid-state fluorescence measurement. 相似文献
966.
Naraso N Nishida J Ando S Yamaguchi J Itaka K Koinuma H Tada H Tokito S Yamashita Y 《Journal of the American Chemical Society》2005,127(29):10142-10143
Aromatic ring-condensed TTF derivatives exhibited excellent p-type FET performances in thin films. Introduction of fused benzene and pyrazine rings to the TTF skeleton was effective to enhance the intermolecular interactions and stability to oxygen. Ordered molecular alignment was confirmed by XRD studies. A pi-stacking structure was observed in the single crystal of diquinoxalinoTTF. 相似文献
967.
Kajitani T Masu H Kohmoto S Yamamoto M Yamaguchi K Kishikawa K 《Journal of the American Chemical Society》2005,127(4):1124-1125
Achiral rodlike molecules possessing an ester group generated a chiral smectic liquid crystal phase. 相似文献
968.
Yamaguchi S Yoshimura I Kohira T Tamaru S Hamachi I 《Journal of the American Chemical Society》2005,127(33):11835-11841
This study has successfully demonstrated that the cooperative action of artificial receptors with semi-wet supramolecular hydrogels may produce a unique and efficient molecular recognition device not only for the simple sensing of phosphate derivatives, but also for discriminating among phosphate derivatives. We directly observed by confocal laser scanning microscopy that fluorescent artificial receptors can dynamically change the location between the aqueous cavity and the hydrophobic fibers upon guest-binding under semi-wet conditions provided by the supramolecular hydrogel. On the basis of such a guest-dependent dynamic redistribution of the receptor molecules, a sophisticated means for molecular recognition of phosphate derivatives can be rationally designed in the hydrogel matrix. That is, the elaborate utilization of the hydrophobic fibrous domains, as well as the water-rich hydrophilic cavities, enables us to establish three distinct signal transduction modes for phosphate sensing: the use of (i) a photoinduced electron transfer type of chemosensor, (ii) an environmentally sensitive probe, and (iii) an artificial receptor displaying a fluorescence resonance energy transfer type of fluorescent signal change. Thus, one can selectively sense and discriminate the various phosphate derivatives, such as phosphate, phospho-tyrosine, phenyl phosphate, and adenosine triphosphate, using a fluorescence wavelength shift and a seesaw type of ratiometric fluorescence change, as well as a simple fluorescence intensity change. It is also shown that an array of the miniaturized hydrogel is promising for the rapid and high-throughput sensing of these phosphate derivatives. 相似文献
969.
Hori M Eades J Hayano RS Pirkl W Widmann E Yamaguchi H Torii HA Juhász B Horváth D Suzuki K Yamazaki T 《Physical review letters》2005,94(6):063401
Cold, two-body antiprotonic helium ions p 4He2+ and p 3He2+ with 100-ns-scale lifetimes, occupying circular states with the quantum numbers ni=28-32 and li=ni-1 have been observed. They were produced by cooling three-body antiprotonic helium atoms in an ultra-low-density helium target at temperature T approximately 10 K by atomic collisions, and then removing their electrons by inducing a laser transition to an autoionizing state. The lifetimes of p 3He2+ against annihilation induced by collisions were shorter than those of p 4He2+, and decreased for larger-ni states. 相似文献
970.
Minghui?Hu Yukio?Yamaguchi Tatsuya?OkuboEmail author 《Journal of nanoparticle research》2005,7(2-3):187-193
Two-dimensional (2D) hexagonally close-packed arrays of water-dispersed gold nanoparticles (NPs) on highly hydrophilic sputter-deposited SiO2 surfaces were fabricated via an evaporation-induced self-assembly process. Using a non-ionic amphiphilic glycol derivative with the thiol head group, 1-mercapto-3,6,9-trioxodecane, as a stabilization ligand, high-concentration Au NPs were stably dispersed in water, and self-assembled into μm-sized well-ordered 2D arrays on SiO2 surfaces during the solvent evaporation on SiO2 surfaces. Due to the non-ionic character of the ligand, the particle–particle interactions may only depend on the capillary and van der Waals forces, and not on the electric double-layer forces that change with ion/electrolyte concentrations during the solvent evaporation. This study provides an approach to fabrication of close-packed 2D arrays of water-dispersed NPs instead of using toxicological organic solvent or complex water-organic phase transfer process. Meanwhile, this approach will make it easier to study their self-assembly mechanisms in a variety of solvents by simplifying ambiguous particle–particle interactions.This revised version was published online in August 2005 with a corrected issue number. 相似文献