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81.
C. C. Hsu P. H. Geil Hideki Miyaji Kenjiro Asai 《Journal of Polymer Science.Polymer Physics》1986,24(10):2379-2401
Glassy isotactic propylene (PP) films of thickness up to 0.3 mm were obtained by an ultraquenching technique. The structure and properties of the as-quenched and subsequently crystallized samples were characterized by various techniques. Electron microscopy indicates the glass has no structure larger than 25 Å. X-ray diffraction shows PP crystallizes from the glass into a smectic structure at ca. ?20°C and then transforms to monoclinic microcrystals at ca. 40°C; a nodular structure (80 to 100 Å in diameter) was observed on the surface. The transformation temperature increases with the film thickness. Annealing above the α-relaxation temperature results in an increase in the nodule size. A correspondence was found between the diameter of the nodules observed on the surface and long spacings obtained by small-angle X-ray scattering from the bulk. Dynamic mechanical spectra show the presence of two relaxation-like peaks at ca. ?10°C and 10°C for the as-ultraquenched samples. X-ray scattering, differential scanning calorimetry (DSC), and torsion pendulum measurements show PP crystallizes from the glass at a temperature, depending on the rate of heating, that corresponds to the lower relaxation peak temperature. 相似文献
82.
83.
Yoshihisa Miyamoto Hideki Miyaji Kenjiro Asai 《Journal of Polymer Science.Polymer Physics》1980,18(3):597-606
The anisotropy of the crystalline relaxation (α relaxation) in oriented poly(vinylidene fluoride) in crystal form II has been studied. The dielectric increment Δε is analyzed on the basis of the two-site model. A linear relation between Δε/χξ and cos2θ is obtained, where χ is the degree of crystallinity, ξ is the ratio of the internal field to the applied field, and θ is the angle between the applied electric field and the molecular axis. The dipole moment changes direction only along the molecular axis in the relaxation in crystal form II; the molecular motion cannot be explained by chain rotation around the molecular axis. Possible models for the α relaxation are proposed: change in conformation with internal rotation can occur in the crystalline chains, and defects in the crystalline regions play an important role in the α relaxation. 相似文献
84.
Summary The coagulation of ferric oxide sol by several organic solvents, such as ethyl alcohol, has been studied. It has been observed
that the coagulation takes place when the dielectric constant of medium is lowered to a certain critical value for coagulation
by the addition of any organic solvent. The lowering of dielectric constant of medium is accompanied by the contraction of
electrical double layer around sol particle, which leads to coagulation.
With 1 figure and I table 相似文献
Zusammenfassung Koagulation eines Ferrioxidsols durch verschiedene organische L?sungsmittel findet statt, wenn die Dielektrizit?tskonstante bis auf einen „kritischen” Wert durch Zufügung irgendeines organischen L?sungsmittels vermindert wird. Die Erniedrigung der DK des Mediums bedingt die Kontraktion der elektrischen Doppelschichten der Solpartikel, so da? Koagulation erfolgt.
With 1 figure and I table 相似文献
85.
86.
Kawaguchi M Okabe T Okudaira S Hanaoka K Fujikawa Y Terai T Komatsu T Kojima H Aoki J Nagano T 《Journal of the American Chemical Society》2011,133(31):12021-12030
Nucleotide pyrophosphatases/phosphodiesterases (NPPs) are ubiquitous membrane-associated or secreted ectoenzymes that have a role in regulating extracellular nucleotide and phospholipid metabolism. Among the members of the NPP family, NPP1 and -3 act on nucleotides such as ATP, while NPP2, -6, and -7 act on phospholipids such as lysophosphatidylcholine and sphingomyelin. NPP6, a recently characterized NPP family member, is a choline-specific glycerophosphodiester phosphodiesterase, but its functions remain to be analyzed, partly due to the lack of highly sensitive activity assay systems and practical inhibitors. Here we report synthesis of novel NPP6 fluorescence probes, TG-mPC and its analogues TG-mPC(3)C, TG-mPC(5)C, TG-mPENE, TG-mPEA, TG-mPhos, TG-mPA, TG-mPMe, and TG-mPPr. Among the seven NPPs, only NPP6 hydrolyzed TG-mPC, TG-mPC(3)C, and TG-mPENE. TG-mPC was hydrolyzed in the cell lysate from NPP6-transfected cells, but not control cells, showing that it is suitable for use in cell-based NPP6 assays. We also examined the usefulness of TG-mPC as a fluorescence imaging probe. We further applied TG-mPC to carry out high-throughput NPP6 inhibitor screening and found several NPP6-selective inhibitors in a library of about 80,000 compounds. Through structure-activity relationship (SAR) analysis, we identified a potent and selective NPP6 inhibitor with an IC(50) value of 0.21 μM. Our NPP6-selective fluorescence probe, TG-mPC, and the inhibitor are expected to be useful to elucidate the biological function of NPP6. 相似文献
87.
Sasakura K Hanaoka K Shibuya N Mikami Y Kimura Y Komatsu T Ueno T Terai T Kimura H Nagano T 《Journal of the American Chemical Society》2011,133(45):18003-18005
Hydrogen sulfide (H(2)S) has recently been identified as a biological response modifier. Here, we report the design and synthesis of a novel fluorescence probe for H(2)S, HSip-1, utilizing azamacrocyclic copper(II) ion complex chemistry to control the fluorescence. HSip-1 showed high selectivity and high sensitivity for H(2)S, and its potential for biological applications was confirmed by employing it for fluorescence imaging of H(2)S in live cells. 相似文献
88.
Yasuo Saruyama Hideki Miyaji Kenjiro Asai 《Journal of Polymer Science.Polymer Physics》1979,17(7):1163-1170
Extra meridional reflections (00l: l = 3, 5, 13, 15, 21) were observed in drawn polyoxymethylene (POM). The 003, 0015, and 0021 x-ray diffraction intensities increase on annealing, while the 005 and 0013 intensities decrease. It is concluded that crystalline regions are of two kinds: in the first, which generates the 003, 0015, and 0021 reflections, the molecular conformation is slightly distorted from the uniform helix by intermolecular steric hindrance between the CH2 groups; and in the second, which generates 005 and 0013 reflections, the molecular conformation is distorted in another way. The second form is converted into the first by annealing. The displacements in the c direction of the CH2 groups and the oxygen atoms from the uniform helix in the first form are about 1.0% and 0.75% of the interval between a CH2 group and an oxygen atom along helix axis of the POM crystal; thus the correct conformation in the stable state is known. The nature of distortion in the second region is not clarified but several characteristics are offered. 相似文献
89.
90.
A recent article by K. K. Tam in this journal stated results on the values of the activation energy for which a nonlinear eigenvalue problem, which arises in the steady-state theory of thermal ignition, has multiple solutions. This report points to an error contained therein and gives the corrected values of the activation energy for which multiplicity occurs.
Zusammenfassung Eine vor kurzem erschienene Arbeit in dieser Zeitschrift von K. K. Tam stellte Ergebnisse für die Werte der Aktivierungsenergie fest, für die ein nichtlineares Eigenwert-Problem, das in der stationären Theorie der thermischen Zündung entsteht, vielfache Lösungen hat. Dieser Bericht weist auf einen darin enthaltenen Fehler hin und gibt die korrigierten Werte der Aktivierungsenergie, für die es vielfache Lösungen gibt.相似文献