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471.
The refractive indices of LiNb1?yTayO3 single crystals grown by the Czochralski method were determined in the wavelength range 5893 to 10600 Å at 20 ± 0.5°C. The results indicate that a single crystal (0.95 < y < 0.96) has zero birefringence. Such composition is independent of the wavelength. 相似文献
472.
Claudia E. Murar Mamiko Ninomiya Satomi Shimura Ufuk Karakus Onur Boyman Jeffrey W. Bode 《Angewandte Chemie (International ed. in English)》2020,59(22):8425-8429
Chemical protein synthesis allows the construction of well‐defined structural variations and facilitates the development of deeper understanding of protein structure–function relationships and new protein engineering strategies. Herein, we report the chemical synthesis of interleukin‐2 (IL‐2) variants on a multimilligram scale and the formation of non‐natural disulfide mimetics that improve stability against reduction. The synthesis was accomplished by convergent KAHA ligations; the acidic conditions of KAHA ligation proved to be valuable for the solubilization of the hydrophobic segments of IL‐2. The bioactivity of the synthetic IL‐2 and its analogues were shown to be equipotent to recombinant IL‐2 and exhibit improved stability against reducing agents. 相似文献
473.
Yamasaki K Sakuma Y Sasaki J Matsumoto K Anzai K Matsuoka K Honda C Tsukada M Endo K Enomoto S 《Analytical and bioanalytical chemistry》2011,401(8):2531-2538
The excretion of essential trace elements, namely, Se, Sr, As, Mn, Co, V, Fe, and Zn into the bile of Se-deficient (SeD) Wistar
male rats was studied using the multitracer (MT) technique, and instrumental neutron activation analysis (INAA). Normal and
Se-control (SeC) rat groups were used as reference groups to compare the effects of Se levels on the behaviors of the essential
trace elements. The excretion (% dose) of Se, Sr, As, Mn, Co, and V increased with Se levels in the liver. The biliary excretion
of Mn and As dramatically enhanced for SeC rats compared with SeD rats, while that of V accelerated a little for SeC rats.
The radioactivity levels of 59Fe and 65Zn in the MT tracer solution were insufficient to measure their excretion into bile. The role of glutathione and bilirubin
for biliary excretion of the metals was discussed in relation to Se levels in rat liver. 相似文献
474.
Keisuke Ichihara Prof. Hidetoshi Kawai Yuka Togari Emi Kikuta Hitomi Kitagawa Prof. Seiji Tsuzuki Dr. Kenji Yoza Prof. Masamichi Yamanaka Prof. Kenji Kobayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3685-3692
Remarkably enhanced stability of the self‐assembled hydrogen‐bonded heterocapsule 1?2 by the encapsulation of 1,4‐bis(1‐propynyl)benzene 3 a was found with Ka=1.14×109 M ?1 in CDCl3 and Ka2=1.59×108 M ?2 in CD3OD/CDCl3 (10 % v/v) at 298 K. The formation of 3 a @( 1?2 ) was enthalpically driven (ΔH°<0 and ΔS°<0) and there was a unique inflection point in the correlation between ΔH° versus ΔS° as a function of polar solvent content. The ab initio calculations revealed that favorable guest–capsule dispersion and electrostatic interactions between the acetylenic parts (triple bonds) of 3 a and the aromatic inner space of 1?2 , as well as less structural deformation of 1?2 upon encapsulation of 3 a , play important roles in the remarkable stability of 3 a @( 1?2 ). 相似文献
475.
Masamichi Kobayashi Fumitoshi Kaneko 《Journal of Dispersion Science and Technology》2013,34(4-5):319-350
Molecular-level structures of lipids and related organic long-chain compounds were investigated by means of vibrational spectroscopic and X-ray diffraction methods. Various spectroscopic techniques applicable to structural studies of lipid systems were developed. Various types of solid-state phase transformations were found in even- and odd-numbered saturated fatty acids and their molecular mechanisms were considered. Crystal structures of some modifications of a series of cis-mono-unsaturated fatty acids were determined by the three-dimensional X-ray analysis and new types of molecular conformation as well as of subcell arrangement of the cis-mono-unsaturated acyl chains were found. An order-disorder type phase transformation accompanied with a partial melting at the interface of the molecular layers was found in some modifications of cis-mono-unsaturated fatty acids. Molecular conformations and crystal structures of the polymorphs of methyl oleate and triglycerides containing an oleoyl chain at the 2-position were investigated on the basis of the spectroscopic data. 相似文献
476.
Riichi Miyamoto Yukiko Ando Chie Kurusu Hong‐zhi Bai Kazuki Nakanishi Masamichi Ippommatsu 《Journal of separation science》2013,36(12):1890-1896
Reproducible fabrication of the hierarchically porous monolithic silica in a large volume exceeding 1000 mL has been established. By the hydrothermal enlargement of the fully accessible small pores to exceed 50 nm in diameter, the capillary force emerged on solvent evaporation was dramatically reduced, which allowed the preparation of crack‐free monoliths with evaporative solvent removal under an ambient pressure. The local temperature inhomogeneity within a reaction vessel in a large volume was precisely controlled to cancel the heat evolved by the hydrolysis reaction of tetramethoxysilane and that consumed to melt ice cubes dispersed in the solution, resulting in large monolithic silica pieces with improved structural homogeneity. Homogeneity of the pore structure was confirmed, both on macro‐ and mesoscales, using SEM, mercury intrusion, and nitrogen adsorption/desorption measurements. Furthermore, the deviations in chromatographic performance were examined by evaluating multiple smaller monolithic columns prepared from the monolithic silica pieces cut from different parts of a large monolith. All the daughter columns thus prepared exhibited comparable performances to each other to prove the overall homogeneity of the mother monolith. Preliminary results on high‐speed separation of peptides and proteins by the octadecylsilylated silica monolith of the above production have also been demonstrated. 相似文献
477.
478.
Masamichi Tsuboi Teruki Ikeda Toyotoshi Ueda 《Journal of Raman spectroscopy : JRS》1991,22(11):619-626
A general method is presented for determining the shape and orientation of the Raman tensor of a molecule in a uniaxial crystal using a Raman microscope. First, equations are derived to connect the Raman tensor components (αxx, αyy, etc.) of a molecule to the Raman tensor components (αaa, αcc, etc.) of a crystal that is composed of molecules in a uniaxial arrangement, with an orientation specified by the two angles χ and θ. Next, a method is presented to obtain a correct set of values of the intensity ratios Iac/Iaa and Icc/Iaa from observed values of the intensity ratios measured with a Raman microscope. To augment the experimental data, the depolarization ratio ρ (for a completely random molecular orientation) is plotted as a function of r1 = αxx/αzz and r2 = αyy/αzz, so that a possible set of r1 and r2 values can be found from an observed value of ρ. The method has been applied to an aspartame IIA crystal (P41). A set of values of r1, r2, χ and θ has been determined for each of the following Raman fundamentals: 1741 cm−1 (ester CO stretch), 1667 cm−1 (amide I), 1275 cm−1 (amide III) and 1204 cm−1 (C Cphenyl stretch), excited at 488.0 nm. 相似文献
479.
Masamichi Kobayashi Tohru Kobayashi Yonghae Cho Fumitoshi Kaneko 《Macromolecular Symposia》1986,5(1):1-20
Various types of molecular assembly of long-chain compounds in solid states were investigated by means of infrared absorption, Raman and Brillouin spectroscopic methods. As for the polymorphism in even-numbered n-fatty acids, three monoclinic modifications, B, C, and E, all consisting of the orthorhombic polyethylene sublattice, give rise to their characteristic infrared and Raman spectra. A dynamical equilibrium between cis and trans conformations of the hydrogen-bonded carboxyl groups in modification C, which is related to the high-temperature stable character of this phase, is reflected to a dramatic change with temperature in the low-frequency Raman spectra. A new type of reversible solid state phase transition was found between two A-type (triclinic) modifications of myristic, palmitic, and stearic acids. The γ→α phase transition of oleic acid was found to be caused by a conformational disordering of polymethylene chains at the lamellar interfacial region. Two basic polytype structures, Mon and Orth II, of stearic acid B were investigated, and it was found that the low-frequency phonon frequencies (below 50 cm−1) were strongly influenced by the polytype structure. Based on the spectroscopic considerations, Orth II was predicted as the thermodynamically stable phase around room temperature compared with Mon, and the stability is responsible for the vibrational free energy term. Some experimental findings which support this prediction were obtained. The values of the stiffness tensor elements of Mon and Orth II, measured by Brillouin scattering, indicate that the mechanical behavior of bulk crystals is very dependent on the polytype structure. The relationship between the mobility of chain molecules and the width of the spectral bands was investigated in a quantitative manner for the case of n-alkane molecules entrapped in the urea inclusion adducts. The changes in the half-width for the polarization components of various Raman bands on the transition from the orthorhombic to the hexagonal phase are interpreted in terms of the correlation functions of the Raman tensor related to the rotational motion of the alkane molecules around the chain axes. 相似文献