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991.
Koji Tsunekawa Fumio Kondo Teruhiko Okada Guo-Gang Feng Lei Huang Naohisa Ishikawa Shoshiro Okada 《BMC neuroscience》2013,14(1):1-11
Background
Domoic acid (DA) is an excitatory amino acid analogue of kainic acid (KA) that acts via activation of glutamate receptors to elicit a rapid and potent excitotoxic response, resulting in neuronal cell death. Recently, DA was shown to elicit reactive oxygen species (ROS) production and induce apoptosis accompanied by activation of p38 mitogen-activated protein kinase (MAPK) in vitro. We have reported that WDR35, a WD-repeat protein, may mediate apoptosis in several animal models. In the present study, we administered DA to rats intraperitoneally, then used liquid chromatography/ion trap tandem mass spectrometry (LC-MS/MS) to identify and quantify DA in the brains of the rats and performed histological examinations of the hippocampus. We further investigated the potential involvement of glutamate receptors, ROS, p38 MAPK, and WDR35 in DA-induced toxicity in vivo.Results
Our results showed that intraperitoneally administered DA was present in the brain and induced neurodegenerative changes including apoptosis in the CA1 region of the hippocampus. DA also increased the expression of WDR35 mRNA and protein in a dose- and time-dependent manner in the hippocampus. In experiments using glutamate receptor antagonists, the AMPA/KA receptor antagonist NBQX significantly attenuated the DA-induced increase in WDR35 protein expression, but the NMDA receptor antagonist MK-801 did not. In addition, the radical scavenger edaravone significantly attenuated the DA-induced increase in WDR35 protein expression. Furthermore, NBQX and edaravone significantly attenuated the DA-induced increase in p38 MAPK phosphorylation.Conclusion
In summary, our results indicated that DA activated AMPA/KA receptors and induced ROS production and p38 MAPK phosphorylation, resulting in an increase in the expression of WDR35 in vivo. 相似文献992.
The Raman and IR. spectra of solid diamminediiodidezinc (II) with 15N and 2H isotopic substitution have been measured. The spectra have been interpreted assuming C2v symmetry for the Zn(NH3)2I2 complex structure. The skeletal stretching metal-ligand modes vs(ZnN), vas(ZnN), vs(ZnI), vas(ZnI) as well as the three bending modes δ(NZnN), δ(IZnI) and δ(IZnN) were assigned by comparison with the spectra of Zn(NH3)2C12 and Zn(NH3)2Br2, and by the observed isotopic shifts of the frequencies. A normal coordinate analysis for the whole complex was carried out using the Local Symmetry Force Field Model. 相似文献
993.
Souichi Ishikawa 《Few-Body Systems》2013,54(1-4):479-482
The triple-alpha (3α) process, in which three 4He nuclei are transformed into a 12C nucleus, is studied in terms of a three-alpha (3-α) model. The reaction rate of the process is calculated via an inverse process, 3-α photodisintegration of a 12C nucleus. Both of 3-α bound and -continuum states are calculated by a Faddeev method with accommodating the long range Coulomb interaction. Results of the 3α reaction rate are about 103 times larger than a standard rate from the Nuclear Astrophysics Compilation of Reaction Rates (NACRE) at a low temperature (T = 107 K), which means our results are remarkably smaller than recent three-body calculations by the method of continuum-discretized coupled-channel. 相似文献
994.
For calcium in the phases IV and V, we estimated the superconducting transition temperature T c by the use of the Allen–Dynes formula. Setting the effective screened Coulomb repulsion constant μ* at 0.1 in the formula, we obtained T c =23.42 K at 100 GPa for Ca-IV and T c =15.87 K at 120 GPa for Ca-V. In order to clarify the origin of such high values of T c , first, we investigated the band character of electrons and found that the high T c is not necessarily related to the so called s–d transfer. Then we analyzed the electron–phonon coupling at each phonon mode in Ca-V where the highest T c in elements has been experimentally observed. As a result, we discovered that an optical mode at the Γ point has the strongest electron–phonon coupling. Such phonon mode can exist only in the complex crystal structure of Ca-V, and the result shows that the high T c seems to be closely linked with the complex crystal structures like Ca-IV and Ca-V. 相似文献
995.
Yumiko Takahashi Atsuo Iida Yoichi Takanishi Toyokazu Ogasawara Ken Ishikawa Hideo Takezoe 《Molecular Crystals and Liquid Crystals》2013,570(1):853-860
Abstract Direct observation of the local layer response of an antiferroelectric liquid crystal to the step form electric field has been carried out by a time resolved synchrotron X-ray micro diffraction measurement. When an electric field was changed from high voltage to OV, corresponding to the ferroelectric to antiferroelectric phase transition, the local layer transformed from the bookshelf to the quasi-bookshelf structure within 0.3 ms. The horizontal chevron structure was found in both the phases, though the decrease in the horizontal chevron angle was observed during a period of 0.2 ms after turning off the electric field. In the antiferroelectric to ferroelectric phase transition process (from OV to high voltage), the layer structure transformed to the bookshelf within 0.04 ms. 相似文献
996.
Yoichitakanishi Mitsutaka Yoshimoto Ken Ishikawa Hideo Takezoe 《Molecular Crystals and Liquid Crystals》2013,570(1):619-625
Abstract Novel liquid crystal compounds with extraordinary large birefringence have been studided from the viewpoint of optical anisotropy. A large birefrinence was obtained in the compounds compared with that in 5CB, while the orientational order parameters determined by FT-IR measurement are almost the same. From the calculated results of molecular polarizability, it is concluded that the large optical anisotropy is mainly caused by the electric anisotropy. 相似文献
997.
998.
Shigeru Ishikawa Tokio Yamabe 《Applied Physics A: Materials Science & Processing》2014,114(4):1339-1346
We evaluated the adsorption energy of a hydrogen molecule in nanocarbons consisting of graphene sheets. The nanocarbon shapes were a pair of disks with separation 2d, a cylinder with radius d, and a truncated sphere with radius d. We obtained the adsorption energy in the form of a 10–4 Lennard–Jones function with respect to 1/d. The values of the potential depth (D) and equilibrium distance (d e), respectively, were 94 meV and 2.89 Å for the disk pair, 158 meV and 3.14 Å for the cylinder, and 203 meV and 3.37 Å for the sphere. When d=d e, the adsorption energy of the disk pair (cylinder) became deeper than ?0.9D, and it approached ?D when the radius (length) increased to more than twice its separation (radius). The adsorption energy of the sphere was increased from ?D to ?0.5D when the radius of the opening increased from 0 to d e. These results suggest that porous carbon materials can increase the adsorption energy by up to ~200 meV if the carbon atoms are arranged on a spherical-like surface with ~7 Å separation. This may lead to practical hydrogen storage for fuel cells. 相似文献
999.
Ryota Ishii Rei Fukuta Fumitaro Ishikawa Masafumi Matsushita Hiroaki Ohfuji Toru Shinmei 《高压研究》2020,40(1):140-147
ABSTRACTDeep-ultraviolet continuous-wave photoluminescence spectroscopy is performed for nano-polycrystalline diamond (NPD) synthesized by a high pressure high-temperature technique. NPD exhibits clear deep-ultraviolet emissions, which originate from intrinsic excitonic transitions assisted by a momentum-conserving phonon with a photon. Surprisingly, the peak emission energy is about 30?meV higher than that of the single-crystalline diamond. Raman scattering spectroscopy indicates that the energy difference should originate from the excitonic properties of the NPD and not the phonon. Hence, NPD has a large bandgap compared to single-crystalline diamond. 相似文献
1000.
Misa Ishikawa Yoshimi Sueishi Nobuyuki Endo Shigeru Oowada Masashi Shimmei Hirotada Fujii Yashige Kotake 《国际化学动力学杂志》2012,44(9):598-603
Scavenging rates of cyclodextrin‐solubilized lipophilic antioxidants, namely catechin, epicatechin, epigallocatechin gallate, and resveratrol, against alkoxyl (RO?) radical were measured with the use of electron paramagnetic resonance (EPR) spin‐trapping method. Results indicated that the scavenging rates of catechin and resveratrol were notably dependent on the solubilizer used, i.e., native β‐cyclodextrin (β‐CD) or heptakis(2,6‐di‐O‐methyl)‐β‐cyclodextrin (DM‐β‐CD). But, epicatechin and epigallocatechin gallate showed almost no dependence on the cyclodextrin used. Catechin's scavenging rate in β‐CD was 66% lower than in DM‐β‐CD; in contrast, resveratrol in β‐CD showed 45% higher rate than in DM‐β‐CD. Based on the reported solution‐NMR structure of the inclusion complex of these antioxidants, it was concluded that the scavenging rate is decreased when the cyclodextrin cavity preferentially encapsulates the antioxidant‐function bearing group, i.e., O‐ and p‐quinolinol group in catechin and resveratrol, respectively. The depth of inclusion of the functional group determines the extent of the scavenging rate difference, suggesting that the cavity wall of the cyclodextrin acts like a barrier that hinders the approach of attacking free radicals. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 598–603, 2012 相似文献