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941.
Ozao R. Ochiai M. Yoshida H. Ichimura Y. Inada T. 《Journal of Thermal Analysis and Calorimetry》2001,64(3):923-932
Gamma-alumina membrane was prepared from anodic (amorphous) alumina (AA) obtained in a sulphuric acid electrolyte. The transformation
scheme, i.e., the crystallization to form metastable alumina polymorphs and the final transition to α-Al2O3 with heating was studied by TG-DTA and X-ray diffraction (XRD) using fixed time (FT) method. When heating at a constant rate,
the crystallization occurred at 900°C or higher and the final formation of α-Al2O3 occurred at 1250°C or higher, which temperatures were higher than the case of using anodic (amorphous) alumina prepared from
oxalic acid electrolyte. Relative content of S of the products was obtained by transmission electron microscope (TEM)-energy
dispersive spectroscopy (EDS). The proposed thermal change of anodic alumina membrane prepared from sulphuric acid is as follows:
1. At temperatures lower than ca 910°C: Formation of a quasi-crystalline phase or a polycrystalline phase (γ-, δ- and θ-Al2O3);
2. 910–960°C: Progressive crystallization by the migration of S toward the surface within the amorphous or the quasi-crystalline
phase, forming S-rich region near the surface;
3. 960°C: Change of membrane morphology and the quasi-crystalline phase due to the rapid discharge of gaseous SO2;
4. 960–1240°C: Crystallization of γ-Al2O3 accompanying δ-Al2O3; and
5. 1240°C: Transition from γ-Al2O3 (+tr. δ-Al2O3) into the stable α-Al2O3.
The amorphization which occurs by the exothermic and the subsequent endothermic reaction suggests the incorporation of SO3 groups in the quasi-crystalline structure.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
942.
H. Yoshida Y. Houshito K. Mashiko K. Masaka S. Nakamura 《Journal of Thermal Analysis and Calorimetry》2001,64(2):453-458
Phase transition process of polyester from phenanthrene, poly(oxyheptamethyleneoxy-2,7-phenantrenedicarbonyl), a main chain
type liquid crystalline polymer, was investigated by simultaneous DSC-XRD measurements using the synchrotron radiation facility
(PF). Three exothermic DSC peaks were observed during cooling from the isotropic liquid state. These DSC peaks were assigned
to the transition from the isotropic liquid to the smectic A, that from the smectic A to C, and that from the smectic C to
the crystalline state, respectively, as determined by XRD profiles. The rate of transition from the smectic A to C was very
slow compared with the liquid crystalline transition and the crystallization. From the DSC-XRD results, the thermal expansion
along c-axis in the crystal and smectic phases are 4.1×10−4 and 1.4×10−3 nm K−1 , respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
943.
H. Yoshida G. Z. Zhang T. Kitamura T. Kawai 《Journal of Thermal Analysis and Calorimetry》2001,64(2):577-583
The mixing state of poly(vinylidene fluoride) (PVDF) and two amorphous polymers,poly(methyl methacrylate) (PMMA) and poly(isopropyl
methacrylate) (PiPMA) were investigated from the viewpoint of crystallization dynamics using simultaneous DSC-FTIR method.
The crystallization rate (R
*) and the growth rate of trans-gauche-trans-gauche’ (TGTG’) conformation (Rc
*) depended on both the blend content (φ) and the crystallization temperature for PVDF/PMMA. The temperature and φ dependency
of R
* and Rc
* were almost the same for PVDF/PMMA. However, R
* and Rc
* depended scarcely on f for PVDF/PiPMA, and the temperature dependency of R
* differed from that of Rc
* for PVDF/PiPMA. These results showed that PVDF and PMMA were miscible on molecular level, and that PVDF/PiPMA was immiscible
and the concentration fluctuation existed in the PVDF-rich phase.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
944.
A S Ratnayake W Y Yoshida S L Mooberry T K Hemscheidt 《The Journal of organic chemistry》2001,66(26):8717-8721
A new alkaloid, nomofungin, has been isolated from the fermentation broth of an unidentified endophytic fungus obtained from the bark of Ficus microcarpa L. The structure of nomofungin was determined by application of spectroscopic methods. The absolute stereochemistry of nomofungin was assigned by using the exciton chirality method. Nomofungin disrupts microfilaments in cultured mammalian cells and is moderately cytotoxic with minimum inhibitory concentrations (MICs) of 2 and 4.5 microg/mL against LoVo and KB cells, respectively. The ring system of nomofungin is unprecedented. 相似文献
945.
Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides having two different substituents at the 2-position, which were synthesized from unsymmetrical ketones and (R)-(−)-chloromethyl p-tolyl sulfoxide in three steps, with cyanomethyllithium gave optically active 2-amino-1-cyano-5,5-disubstituted-1,3-cyclopentadienes with very high asymmetric induction from the sulfoxide chiral center. The products were converted to the enantiomerically pure 4,4-disubstituted 2-cyclopentenones by heating with phosphoric acid in acetic acid. 相似文献
946.
Phase transitions of hexatriacontane (C36) and octacosane (C28), both as the solution grown single crystal (SGC) and polycrystalline aggregates (MCC) prepared by cooling at 1 K min–1 from the isotropic liquid state, were measured by the simultaneous DSC-FTIR method. MCC of C36 showed the freezing of the high temperature stable phase, which had a slight lower order of the lattice vibration mode comparing with the room temperature stable phase. MCC of C28 demonstrated thermo-reversible phase transition, however, had a binomial distribution of crystal stability of the monoclinic phase.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
947.
Yoshida H. Masuzaki M. Ooyama S. Ando R. Kamada K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1999,27(3):682-687
High-power broad-band millimeter-wave radiation is emitted from a plasma in a strong Langmuir turbulence state driven by an intense relativistic electron beam. We measured directivity and spectrum of this radiation with a filter-bank spectrometer, a heterodyne spectrometer, and a filter-waveguide-combination spectrometer covering 18-140 GHz. The directivity measurement indicated that the radiation was relativistically beamed. The observed spectra were nearly flat up to about 40 GHz and declined steeply above 40 GHz. Discussion is given on the experimental results in connection with the collective Compton boosting model proposed by Benford and Weatherall (1992) 相似文献
948.
949.
Luís A. S. De A. Prado Eduardo Radovanovic Heloise O. Pastore Inez V. P. Yoshida Iris L. Torriani 《Journal of polymer science. Part A, Polymer chemistry》2000,38(9):1580-1589
Poly(phenylsilsesquioxane) (PPSQ) polymers that were obtained from different synthetic routes were comparatively studied. The polymers were characterized by infrared and solid‐state 29Si NMR spectroscopies. According to the results of X‐ray diffraction and thermogravimetric analyses, the materials richest in silanol showed a less organized network and lower weight loss temperature. The morphology of the products was influenced by the preparation conditions. PPSQ, with a morphology rich in spherical particles, was achieved with an n‐hexadecyltrimethylammonium bromide template in the reaction medium, whereas the morphology of this polymer obtained in the absence of the template was featureless. Small‐angle X‐ray scattering analyses revealed that the PPSQ samples showed a predominance of surface‐fractal behavior. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1580–1589, 2000 相似文献
950.
Masanori Taguchi Ikuyoshi Tomita Yasuhiko Yoshida Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2001,39(4):495-499
An end‐π‐allylnickel macroinitiator ( 3 ) was prepared by the reaction of poly(ethylene glycol) allenyl methyl ether with an excess amount (5 equiv) of [(π‐allyl)NiOCOCF3]2 ( 1 ) in the presence of PPh3 ([PPh3]/[ 1 ] = 1). The resulting macroinitiator was used as an initiator for the polymerization of 1‐phenylethyl isonitrile ( 4a ) to give a block copolymer [poly(ethylene glycol)‐block‐poly( 4a )]. The molecular weight and composition of the block copolymers were controlled by the molecular weight of 3 and the ratio of 4a to 3 . © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 495–499, 2001 相似文献