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91.
N. Yoshikawa S. Yamabe N. Kanehisa T. Inoue H. Takashima K. Tsukahara 《Journal of Physical Organic Chemistry》2011,24(11):1110-1118
Electronic structures of binuclear ruthenium complexes [Ru2(terpy)2(tppz)]4+ ( 1A ) and [Ru2Cl2(L)2(tppz)]2+ {L = bpy ( 2A ), phen ( 3A ), and dpphen ( 4A )} were studied by density functional theory calculations. Abbreviations of the ligands (Ls) are bpy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline, dpphen = 4,7‐diphenyl‐1,10‐phenanthroline, terpy = 2,2′:6′,2″‐terpyridine, and tppz = tetrakis(2‐pyridyl)pyrazine. Their mononuclear reference complexes [Ru(terpy)2]2+ ( 1B ) and [RuClL(terpy)]+ {L = bpy ( 2B ), phen ( 3B ), and dpphen ( 4B )} were also examined. Geometries of these mononuclear and binuclear Ru(II) complexes were fully optimized. Their geometric parameters are in good agreement with the experimental data. The binuclear complexes were characterized by electrospray ionization mass spectrometry, UV–Vis spectroscopy, and cyclic voltammograms. Hexafluorophosphate salts of binuclear ruthenium complexes of 3A and 4A were newly prepared. The crystal structure of binuclear complex 1A (PF6)4 was also determined. Orbital interactions were analyzed to characterize the metal‐to‐ligand charge‐transfer (MLCT) states in these complexes. The Cl? ligand works to raise the orbital energy of the metal lone pair, which leads to the low MLCT state. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
92.
Nishida A Yamada M Kanazawa T Takashima Y Ouchi K Okada H 《Chemical & pharmaceutical bulletin》2010,58(11):1480-1486
To evaluate the usability of silk protein (sericin, SC) as a sustained-release material, the physicochemical properties of SC and the release profiles of model drugs from SC gel, sponge and film were studied. Heat aids the dissolution of SC. The molecular weight of SC tended to decrease as the heating temperature and heating time increased. The gel and sponge formed by SC were moldable and consisted of high molecular weight SC polymers (250 kDa and about 400 kDa). SC film was easily broken and exhibited elastic distortion. The addition of moisture-retaining plasticizer (glycerin and sorbitol) improved the film-forming characteristics of SC. The results suggested that SC is practical as a moldable gel and sponge, and as a tensible film. To evaluate the release profiles of small molecules, fluorescein isothiocyanate-dextran ((1) FD4, 4 kDa and (2) FD70, 70 kDa) were used as two model drugs with significantly different molecular weights, and fluorescein isothiocyanate-albumin ((3) FA, 66 kDa) was used as a charged drug. Each was formulated in SC gel, sponge and film. In each preparation, the release rate of the model drugs tended to be FA相似文献
93.
Ryuta Mizutani Akihisa Takeuchi R. Yoshiyuki Osamura Susumu Takekoshi Kentaro Uesugi Yoshio Suzuki 《Micron (Oxford, England : 1993)》2010,41(1):90-95
To estimate the spatial resolution of microtomographs, a test object on the submicrometer scale was prepared by focused ion beam milling and subjected to microtomographic analysis. Since human tissues are composed of cells and extracellular matrices with micrometer and submicrometer structures, it is important to investigate the three-dimensional spatial resolution of microtomographs used to visualize microstructures of human tissues. The resolutions along the direction within the tomographic slice plane (in-plane resolution) and perpendicular to it (through-plane resolution) were determined from the modulation transfer function of square-wave patterns. The in-plane resolution was estimated to be 1.2 μm from the modulation transfer function of the non-zoom image. In contrast, the zoom image gave the in-plane resolution of 0.8 μm. This in-plane resolution is comparable to the through-plane resolution, which was estimated to be 0.8 μm. Although the two-dimensional radiographs were taken with the pixel width of half the X-ray optics resolution, these three-dimensional resolution analyses indicated that the zoom reconstruction should be performed to achieve the in-plane resolution comparable to the X-ray optics resolution. The submicrometer three-dimensional analysis was applied in the structural study of human cerebral tissue stained with high-Z elements and the obtained tomograms revealed that the microtomographic analysis allows visualization of the subcellular structures of the cerebral tissue. 相似文献
94.
Shuhei Furukawa Kenji Hirai Keiji Nakagawa Yohei Takashima Ryotaro Matsuda Takaaki Tsuruoka Mio Kondo Rie Haruki Daisuke Tanaka Hirotoshi Sakamoto Satoru Shimomura Osami Sakata Susumu Kitagawa 《Angewandte Chemie (International ed. in English)》2009,48(10):1697-1697
A porous copper coordination framework grew epitaxially as a single crystal on the surface of a single crystal of a porous zinc coordination framework, as described by S. Kitagawa and co‐workers in their Communication on page 1766 ff. The picture shows the structural relationship between the copper and zinc frameworks, which has been unveiled by synchrotron surface X‐ray diffraction measurements; in‐plane rotational epitaxial growth compensates for the different lattice constants of the two crystals.
95.
Masaki Takashima 《Fluid Dynamics Research》1996,17(6):293-310
The stability against small disturbances of the pressure-driven plane laminar motion of an electrically conducting fluid under a transverse magnetic field is investigated. Assuming that the outer regions adjacent to the fluid layer are electrically non-conducting and not ferromagnetic, the appropriate boundary conditions on the magnetic field perturbations are presented. The Chebyshev collocation method is adopted to obtain the eigenvalue equation, which is then solved numerically. The critical Reynolds number Rc, the critical wave number αc, and the critical wave speed cc are obtained for wide ranges of the magnetic Prandtl number Pm and the Hartmann number M. It is found that except for the case when Pm is sufficiently small, the magnetic field has both stabilizing and destabilizing effects on the fluid flow, and that for a fixed value of M the fluid flow becomes more unstable as Pm increases. 相似文献
96.
Prof. Dr. Taku Shoji Sho Takagaki Yukino Ariga Akari Yamazaki Mutsumi Takeuchi Prof. Dr. Akira Ohta Dr. Ryuta Sekiguchi Dr. Shigeki Mori Prof. Dr. Tetsuo Okujima Prof. Dr. Shunji Ito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(9):1931-1935
In this paper, we describe an efficient and atom-economical synthesis of highly functionalized pyrroles, pentafulvenes, and pyrrolopyridines by [2+2] cycloaddition–retroelectrocyclization of N-substituted propargylamines with tetracyanoethylene, followed by the treatment of the resulting tetracyanobutadiene derivatives with silica gel. In this reaction, silica gel plays an important role to promote the intramolecular cyclization to afford the heterocyclic products from the tetracyanobutadiene intermediates. The products were obtained selectively depending on the substituent on the nitrogen atom of the starting propargylamines. 相似文献
97.
H. Kawamura H. Tagomori N. Matsuoka Y. Takashima S. Tawaki N. Momoshima 《Journal of Radioanalytical and Nuclear Chemistry》1999,242(3):717-720
Microwave digestion was applied as pretreatment of environmental samples for the determination of lead isotope ratios by ICP-MS.
Microwave digestion decomposed the samples easily and rapidly without lead contamination. The lead isotope ratios could be
measured directly by ICP-MS without tedious lead purification, because the influence of the matrix elements on measurements
of lead isotope ratios is small enough to be ignored. 相似文献
98.
HYDROGEN PEROXIDE MEDIATES UV-INDUCED IMPAIRMENT OF ANTIGEN PRESENTATION IN A MURINE EPIDERMAL-DERIVED DENDRITIC CELL LINE 总被引:3,自引:0,他引:3
Gisela Caceres-Dittmar Kiyoshi Ariizumi Shan Xu Felix J. Tapia Paul R. Bergstresser Akira Takashima 《Photochemistry and photobiology》1995,62(1):176-183
Abstract— Ultraviolet-B (290–320 nm) radiation is known to impair the antigen-presenting cell (APC) function of Langerhans cells (LC), skin-specific members of the dendritic cell (DC) family. We sought to address mechanisms of this effect, focusing on the role played by hydrogen peroxide. For this purpose, we used a newly established murine DC line, XS52, which resembles epidermal LC in several respects. The APC capacity of XS52 cells, using two different CD4* T cell clones as responders, was inhibited significantly (>50%) by exposure to UV radiation (unfiltered FS20 sunlamps) at relatively small fluences (50–100 J/m2 ). Ultraviolet radiation also inhibited growth factor-dependent proliferation of XS52 cells. On the other hand, cell surface phenotype was relatively well preserved after irradiation; expression levels of B7-1 and B7-2 were reduced slightly, while other molecules ( e.g. Ia, CD54, CD1 la and CD18) were not affected. With respect to the role played by hydrogen peroxide, pretreatment with purified catalase (900 U/mL) prevented UV-induced inhibition of APC function. Short-term exposure to 3 miM H2 02 or f-butyl H2 02 mimicked UV radiation by inhibiting APC function. Finally, intrinsic catalase activity was substantially lower in XS52 cells compared with Pam 212 keratinocytes. These results indicate that the generation of hydrogen peroxide alone is sufficient to produce some, but not all, of the deleterious effects of UV radiation on DC derived from the skin. 相似文献
99.
Ryuta Maruyama Mohd. Maniruzzaman Seigou Kawaguchi Koichi Ito 《Macromolecular Symposia》2002,179(1):133-140
Aqueous micellar polymerization of amphiphilic poly(ethylene oxide) macromonomers carrying p-vinylphenylheptyl end-group has been found to persist to proceed after turning-off of the UV-irradiation. Simulation of the kinetics revealed a high propagation rate constant coupled with a low termination constant, supporting a living-like polymerization at the initial stage. Micellar copolymerization with equimolar styrene also proceeded after UV-irradiation. Polymer molecular weights in MALLS-SEC were also found to evolve with time after irradiation. 相似文献
100.