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991.
Kaoru Taketani Kenji Mishima Takashi Ino Tamaki Yoshioka Suguru Muto Takahiro Morishima Hirohiko M. Shimizu Takayuki Oku Junichi Suzuki Takenao Shinohara Kenji Sakai Hiromi Sato Katsuya Hirota Yoshie Otake Masaaki Kitaguchi Masahiro Hino Yoshichika Seki Yoshihisa Iwashita Masako Yamada Masahiro Ichikawa Takanori Sugimoto Shinsuke Kawasaki Sachio Komamiya Yoshio Kamiya Hidetoshi Otono Satoru Yamashita Peter Geltenbort 《Physica B: Condensed Matter》2009,404(17):2643-2645
We obtained highly polarized very cold neutrons through a quadrupole magnet with a large aperture. When neutrons go through a quadrupole magnet, parallel-spin neutrons are attracted to the magnet axis and anti-parallel-spin neutrons are repelled off the axis. Therefore, the neutrons through a sufficiently long quadrupole magnet have completely parallel-spin. At the downstream of the quadrupole magnet, we placed another quadrupole magnet to divide neutrons into two regions depending on their spin directions. We obtained the neutron polarization from the integrated count of the two regions and found it was 99.88±0.09 (stat.)±0.05 (syst.)%. 相似文献
992.
Long-Time Exudation of Plasticizer from Swollen Rubber Vulcanizates: (I) Diffusivity during Swelling
Yoshio Hoei 《Journal of Macromolecular Science: Physics》2013,52(3):580-591
This series of two papers attempt to obtain appropriate estimates of diffusivity during extensive swelling/exudation of plasticizer in vulcanized rubbers and make clearer the difference in their behaviors in terms of diffusivity and time taken to reach equilibrium. Therefore, two mutually consistent kinetic models for extensive absorption/desorption are presented first. A particular treatment of the models is an incorporation of characteristic parameters into the theoretical diffusion coefficient, based on the Flory–Rehner theory. In this first paper, using the model for swelling (or absorption), we confirm that it can provide realistic diffusion coefficients by analyzing experimental data on the swelling of several standard rubber vulcanizates immersed in plasticizer (i.e., dioctyl phthalate), taken from the literature. In the second paper, the counterpart for exudation will provide both diffusivities during extensive exudation and time periods taken to reach equilibrium using the corresponding data. The results have a great difference from those of the swelling case, with the cause being explained. 相似文献
993.
Yoshio Hoei 《Journal of Macromolecular Science: Physics》2013,52(3):592-601
In the first paper in this series, two mutually consistent kinetic models were put forth to evaluate concentration-dependent diffusion coefficients of plasticizer during the extensive swelling and exudation processes of several typical rubber vulcanizates containing it. According to the model for swelling, the diffusivities were estimated using experimental data taken from the literature. In this paper the counterpart for exudation is applied to the exudation data of the same systems and diffusivities and exudation times taken to reach equilibrium are both estimated. The predicted results are compared with those of the swelling case. The results of both cases are used to account for the remarkable difference between the swelling/exudation behaviors and the lengthy exudation time as compared with the corresponding swelling time. 相似文献
994.
YANGHui LUTian-hong YoshioMasaki 《高等学校化学研究》2004,20(5):617-623
The effect of the improvement of commercial activated carbon(AC) on its specific capacitance and high rate capability of double layer(dl) charging/discharging process has been studied. The improvement of AC was carried out via a secondary activation under steam in the presence of catalyst NiCl2, and the suitable condition was found to be a heat treatment at about 875 ℃ for 1 h. Under those conditions, the discharge specific capacitance of the improved AC increases up to 53. 67 F/g, showing an increase of about 25% as compared with that of as-received AC. The good rectangular-shaped voltammograms and A.C. impedance spectra prove that the high rate capability of the capacitor made of the improved AC is enhanced significantly. The capacitance resistance (RC) time constant of the capacitor containing the improved AC is 1.74 s, which is much lower than that of the one containing as-received AC(an RC value of 4. 73 s). It is noted that both kinds of AC samples show a similar specific surface area and pore size distribution, but some changes have taken place in the carbon surface groups, especially a decrease in the concentration of surface carbonyl groups after the improvement, which have been verified by means of X-photoelectron spectroscopy. Accordingly, it is suggested that the decrease in the concentration of surface carbonyl groups for the improved AC is beneficial to the organic electrolyte ion penetrating into the pores, thus leading to the increase in both the specific capacitance and high rate capability of the supercapacitor. 相似文献
995.
Katsuhiro Maeda Seiji Okada Eiji Yashima Yoshio Okamoto 《Journal of polymer science. Part A, Polymer chemistry》2001,39(18):3180-3189
Two novel phenylacetylene derivatives bearing diethylaminomethyl groups at the meta position on phenyl groups [3‐(N,N‐diethylaminomethyl)phenyl]acetylene ( 1 ) and [3,5‐bis(N,N‐diethylaminomethyl)phenyl]acetylene ( 2 ) were synthesized and polymerized with [Rh(nbd)Cl]2 (nbd: norbornadiene). Both monomers gave highly cis–transoidal stereoregular polymers that exhibited an induced circular dichroism (ICD) in the UV–visible region, probably because of a prevailing one‐handed helical conformation upon complexation with optically active carboxylic acids such as mandelic acid and lactic acid. The sign of the Cotton effects reflected the absolute configuration of the chiral acids. Therefore, these polymers can be used as a novel probe for determining the configuration of chiral acids. The polymers were stable in the presence of chiral acids in solution. The poly‐ 1 complexed with chiral acids exhibited a split‐type ICD, whereas the poly‐ 2 complexed with chiral acids showed a different, non‐split‐type ICD. The ICD pattern of the poly‐ 1 /chiral acids complexes dramatically changed with an increase in the concentration of the chiral acids, thus showing a non‐split‐type ICD similar to those of the poly‐ 2 /chiral acid complexes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3180–3189, 2001 相似文献
996.
Mamoru Fujitsuka Keisuke Matsumoto Osamu Ito Takashi Yamashiro Yoshio Aso Tetsuo Otsubo 《Research on Chemical Intermediates》2001,27(1-2):73-88
Photoinduced charge separation (CS) and charge recombination (CR) processes of octathiophene-C60 and dodecathiophene-C60 dyad molecules (8T-C60 and 12T-C60, respectively) have been investigated by time-resolved absorption spectroscopy in the visible and near-IR regions. In toluene, 18T*-C60 and 112T*-C60 showed energy transfer to 1C*-moiety predominantly, while 60 contribution of CS was small. In various polar solvents, on the other hand, CS states were predominantly formed from both singlet-excited oligothiophene and 1C6*0-moiety because of lower CS level in polar environments. The CR process generating both the triplet state of oligothiophene and the ground state was confirmed in anisole and anisole/toluene mixture within a few nanoseconds. In more polar solvents (dielectric constant (∈s) > 7), CS states showed two components decay: Slow decay component showed lifetime in the hundred nanosecond-region, while fast component decayed within a few nanoseconds. For the mechanism of the long-living CS state in polar solvents (∈s > 7), equilibrium between the CS state and the triplet state was proposed. Furthermore, effects of length of oligothiophene on the CS and CR processes were discussed on the basis of the free energy changes. 相似文献
997.
The OH proton chemical shifts of methanol referred to the CH3 proton in the methanol — benzene-d6 system have been measured from room temperature up to the supercritical region. MD simulations have also been performed at the same composition as experiment at 575 K. The chemical shift results in the supercritical region are in good agreement with those of pure methanol at the same density within experimental errors. The results of NMR and MD simulation suggest that the hydrogen-bonded structure of methanol is practically not affected by addition of benzene molecules. 相似文献
998.
Shinji Watanabe Atsushi Kobayashi Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1994,32(5):909-915
New polyarylates and aromatic polyethers were synthesized from 1,2-bis(4-hydroxyphenyl)-1,2-diphenylethylene, and aromatic dicarboxylic acid chlorides and aromatic dihalides, respectively. The polyarylates having inherent viscosities of 0.28–1.05 dL/g were synthesized by either the two-phase method or the high-temperature solution method. All the polymers were easily soluble in N-methyl-2-pyrrolidone, N,N-dimethylformamide, pyridine, m-cresol, 1,4-dioxane, and 1,1,2,2-tetrachloroethane. They have glass transition temperatures in the range of 217–250°C and showed no weight loss below 315°C in both air and nitrogen atmospheres. Aromatic polyethers with inherent viscosities of 0.85–1.21 dL/g were obtained by the polycondensation of 1,2-bis(4-hydroxyphenyl)-1,2-diphenylethylene and aromatic difluorides in the presence of potassium carbonate. These polymers having glass transion temperatures of 193–220°C were also soluble in the aforementioned solvents and stable up to around 350deg;C in both atmospheres. © 1994 John Wiley & Sons, Inc. 相似文献
999.
Crystals of two new phases, which were recently found in the system CaO-Al2O3-MgO lying on the join connecting calcium hexaaluminate (CaAl12O19) of the magnetoplumbite structure and spinel (MgAl2O4), were grown by the floating zone method. The stoìchìometrìc formulas for these two phases can be given as Ca2Mg2Al28O46 (CAM-I) and CaMg2Al16O27 (CAM-II). On the basis of the stacking sequence revealed by high-resolution electron microscopy, the structure models were made, and further, the structure refinement was conducted by using single crystal X-ray diffraction data. It was shown that both phases have magnetoplumbite-related structures composed of two types of structure units, M(CaAl12O19; magnetoplumbite unit) and S (Mg2Al4O8; spinel unit), and that the stacking sequences are (M2S)n for CAM-I (c = 79.810 Å) and (MS)n for CAM-II (c = 31.288 Å). In the terminology of hexagonal ferrite structure system, CAM-I is of the "X-type structure" with space group R
m and CAM-II is of the "W-type structure" with P
m 2 symmetry. 相似文献
1000.
Fumihiko Akutsu Kenichi Takahashi Yoshio Kasashima Mari Inoki Kiyoshi Naruchi 《Macromolecular rapid communications》1995,16(7):495-501
Novel poly(arylene ether)s with a rigid and zigzag 4,4″-o-terphenyldiyl structure, introduced into the polymer backbone were synthesized by nucleophilic displacement reaction of 4,4″-dihydroxy-o-terphenyl with several activated aromatic dihalides in virtually quantitative yields. The poly(arylene ether)s having high molecular weight show both good solubility in common organic solvents and high thermal stability up to 545°C. They are amorphous with glass transition temperatures of 160–200°C. 相似文献