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101.
The thermolysis of a pentacoordinate fluorodisilane bearing an 8-(dimethylamino)-1-naphthyl group in the presence of 2,3,4,5,6-pentaphenylfulvene or 14-phenyldibenzofulvene affords a silylene-fulvene adduct bearing a zwitterionic structure attributable to the silaylide, but it spontaneously undergoes subsequent intramolecular cyclization reaction between the silicon atom and the aromatic carbon atom in the fulvene moiety followed by a sigmatropic proton migration to form a neutral silicon-containing six- or five-membered ring product. 相似文献
102.
Y. Aratono C. Sagawa M. Nakashima M. Nakada K. Hojou M. Saeki 《Hyperfine Interactions》1992,70(1-4):905-908
The chemical reactions induced by 40 keV He+ ions in α-Fe2O3 and Fe3O4 were investigated by the conversion electron Mössbauer spectroscopy(CEMS). Magnetite(Fe3O4) was formed upon the bombardment of α-Fe2O3, whereas no change was observed in Fe3O4. The initial G value for Fe3O4 formation is estimated to be 3.5×10?4 for 100 nm depth from the surface. The application of CEMS and sputtering technique to ion bombardment chemistry is discussed. 相似文献
103.
Dr. Shunta Nakamura Dr. Hayato Sakai Dr. Masaaki Fuki Rikuto Ooie Dr. Fumitaka Ishiwari Prof. Dr. Akinori Saeki Prof. Dr. Nikolai V. Tkachenko Prof. Dr. Yasuhiro Kobori Prof. Dr. Taku Hasobe 《Angewandte Chemie (International ed. in English)》2023,62(8):e202217704
We newly synthesized a series of homo- and hetero-tetracene (Tc) oligomers to propose a molecular design strategy for the efficient exciton transport in linear oligomers by promoting correlated triplet pair (TT) dissociation and controlling sequential exciton trapping process of individual doubled triplet excitons (T+T) by intramolecular singlet fission. First, entropic gain effects on the number of Tc units are examined by comparing Tc-homo-oligomers [(Tc)n: n=2, 4, 6]. Then, a comparison of (Tc)n and Tc-hetero-oligomer [TcF3-(Tc)4-TcF3] reveals the vibronic coupling effect for entropic gain. Observed entropic effects on the T+T formation indicated that the exciton migration is rationalized by number of possible TT states increased both by increasing the number of Tc units and by the vibronic levels at the terminal TcF3 units. Finally, we successfully observed high-yield exciton trapping process (trapped triplet yield: ΦTrT=176 %). 相似文献
104.
Yotaro Morishima Toru Kitani Takaomi Kobayashi Yasuhiro Saeki Shun-ichi Nozakura Takeshi Ohno Shunji Kato 《Photochemistry and photobiology》1985,42(5):457-464
Abstract— Anionic polyelectrolytes functionalized with the 5-deazaflavin group (dFl) were synthesized. The lifetime of the triplet excited dFl in the polyelectrolytes with a 2-mol% dFl content (AdFl-2) was about 10 times longer than that of a low molecular weight analog (AdFl-M). 2-Mercaptoethanol (RSH) reduced the triplet dFl with the rate constant of k red = 2.01 × 108 M −1 s−1 for AdFl-M and k red = 4.4 × 107 M −1 s−1 for AdFl-2. A zwitterionic viologen (SPV) oxidized the triplet dFl with the rate constant of k red = 3.69 × 109 M −1 s−1 for AdFl-M and k ox = 7.4 × 108 M−1 s−1 for AdFl-2. The smaller rate constants for the polymer system were discussed in terms of the hindering effect of the macromolecular microenvironment. The back electron transfer was shown to be drastically slowed in the AdFl-2-SPV system as a result of the intensive electrostatic effect of the polyelectrolytes. The buildup of the viologen radicals was studied under the steady-state illumination of the three component systems including viologen and RSH. The dFl group was demonstrated to serve as a very efficient photosensitizer in the oxidative cycle in case back electron transfer was retarded. This is the case of the AdFl-2-SPV system which gave the quantum yield of about 0.4 for the SPV− buildup. By comparison, the AdFl-2-MV2 + system resulted in a much slower buildup of MV +radicals. 相似文献
105.
Disilanyl Double‐Pillared Bisternaphthyl (SiDPBT): Synthesis and Interfused Packing Structures with Herringbone and π‐Stack Motifs 下载免费PDF全文
Dr. Waka Nakanishi Naoto Matsuyama Daisuke Hara Akinori Saeki Dr. Shunpei Hitosugi Prof. Shu Seki Prof. Hiroyuki Isobe 《化学:亚洲杂志》2014,9(7):1782-1785
A silacyclophane molecule with two disilanyl pillars and two oligoarylene units was synthesized. The molecule was packed in a single crystal with a new motif interfusing π‐stack and herringbone packing structures. The hole transporting ability of the solid was revealed by using the flash‐photolysis time‐resolved microwave conductivity method. The molecular structure, albeit a singly‐bonded arylene macrocycle, was rigidified by the unique packing array, which favorably contributed to the hole transporting ability of the solid via the small reorganization energy through the charge transport. 相似文献
106.
Saeki D Sugiura S Kanamori T Sato S Mukataka S Ichikawa S 《Langmuir : the ACS journal of surfaces and colloids》2008,24(23):13809-13813
We developed a microfluidic device to form monodisperse droplets with high productivity by anisotropic elongation of a thread flow, defined as a threadlike flow of a dispersed liquid phase in a flow of an immiscible, continuous liquid phase. The thread flow was anisotropically elongated in the depth direction in a straight microchannel with a step, where the microchannel depth changed. Consequently, the elongated thread flow was given capillary instability (Rayleigh-Plateau instability) and was continuously transformed into monodisperse droplets at the downstream area of the step in the microchannel. We examined the effects of the flow rates of the dispersed phase and the continuous phase on the droplet formation behavior, including the droplet diameter and droplet formation frequency. The droplet diameter increased as the fraction of the dispersed-phase flow rate relative to the total flow rate increased and was independent of the total flow rate. The droplet formation frequency proportionally increased with the total flow rate at a constant dispersed-phase flow rate fraction. These results are explained in terms of a mechanism similar to that of droplet formation from a cylindrical liquid thread flow by Rayleigh-Plateau instability. The microfluidic device described was capable of forming monodisperse droplets with a 160-microm average diameter and 3-microm standard deviation at a droplet formation frequency of 350 droplets per second from a single thread flow. The highest total flow rate achieved was 6 mL/h using the present device composed of a straight microchannel with a step. We also demonstrated parallel droplet formation by anisotropic elongation of multiple thread flows; the process was applied to form W/O and O/W droplets. The highly productive droplet formation process presented in this study is expected to be useful for future industrial applications. 相似文献
107.
Y. Kobayashi S. Saeki M. Yoshida D. Nagao M. Konno 《Journal of Sol-Gel Science and Technology》2008,45(1):35-41
This paper describes a method for fabricating spherical submicron-sized silica particles that contained magnetite nanoparticles
(magnetite/silica composite particles). The magnetite nanoparticles with a size of ca. 10 nm were prepared according to the Massart method, and were surface-modified with carboxyethylsilanetriol. The fabrication
of magnetite/silica composite particles was performed in water/ethanol solution of tetraethoxyorthosilicate with ammonia catalyst
in the presence of the surface-modified magnetite nanoparticles. The magnetite/silica composite particles with a size of ca. 100 nm were successfully prepared at 0.05 M TEOS, 15 M water, and 0.8 M ammonia with injection of the magnetite nanoparticle
colloid at 2 min after the initiation of hydrolysis reaction of TEOS. Magnetite concentration in the composite particles could
be raised to 17.3 wt.% by adjustment of the injected amount of the magnetite colloid, which brought about the saturation magnetization
of 7.5 emu/g for the magnetite/silica composite particles. 相似文献
108.
Odo J Kimura A Matsu-Ura A Ohnishi Y Saeki Y Yoshida A Hayashi K Inoguchi M Ueki T 《Chemical & pharmaceutical bulletin》2010,58(12):1576-1581
The scavenging effects of metal complexes of thiacalix[4]arenetetrasulfonate (Me-TCAS[4], Me=H?, Fe3(+), Mn3(+), Mn2(+), Cu2(+), and Zn2(+)) on superoxide anion radicals (O??) generated from the xanthine-xanthine oxidase system were investigated by the nitroblue tetrazolium (NBT) method and electron spin resonance (ESR) spin-trapping method using 5,5-dimethyl-1-pyrroline-N-oxide as a trapping reagent. As a reference, calix[4]arenetetrasulfonate (H?)-CAS[4]), calix[6]arenehexasulfonate (H?-CAS[6]) and calix[8]areneoctasulfonate (H?-CAS[8]) were also examined. The results by the NBT method indicated that Fe3(+)- and Mn3(+)-TCAS[4] exhibited the highest O?? scavenging activity among Me-TCAS[4] and H?-CAS[n] (n = 4, 6, 8) in this study. The IC?? values of Fe3(+)- and Mn3(+)-TCAS[4] for O?? scavenging activity were estimated to be 5.3 and 7.8 μM, respectively, and were almost the same as those of tannin acid, catechin and their derivatives, which are known as very effective scavengers of O??. Scavenging activities were in the order of Fe3(+)- and Mn3(+)-TCAS[4]>Mn2(+)-, Cu2(+)-, and Zn(2+)-TCAS[4]>H(2)-TCAS[4] and H?-CAS[n] (n=4, 6, 8). Each activity of Me-TCAS[4] (Me=Fe3(+), Mn3(+), Mn2(+), Cu2(+), and Zn2(+)) was higher than that of the corresponding metal ion, indicating that H?-TCAS[4] has the ability to raise the activity of the metal ion itself by forming a complex. Also, the ESR spin-trapping method revealed that Fe3(+)- and Mn3(+)-TCAS[4] showed high O?? scavenging activities, similarly to the results by the NBT method. 相似文献
109.
Si-Si Liu Fei Jin Yi-Shi Liu Yoshiko Murakami Yukihiko Sugita Takayuki Kato Xiao-Dong Gao Taroh Kinoshita Motoyuki Hattori Morihisa Fujita 《Molecules (Basel, Switzerland)》2021,26(18)
Glycosylphosphatidylinositol (GPI) anchor modification is a posttranslational modification of proteins that has been conserved in eukaryotes. The biosynthesis and transfer of GPI to proteins are carried out in the endoplasmic reticulum. Attachment of GPI to proteins is mediated by the GPI-transamidase (GPI-TA) complex, which recognizes and cleaves the C-terminal GPI attachment signal of precursor proteins. Then, GPI is transferred to the newly exposed C-terminus of the proteins. GPI-TA consists of five subunits: PIGK, GPAA1, PIGT, PIGS, and PIGU, and the absence of any subunit leads to the loss of activity. Here, we analyzed functionally important residues of the five subunits of GPI-TA by comparing conserved sequences among homologous proteins. In addition, we optimized the purification method for analyzing the structure of GPI-TA. Using purified GPI-TA, preliminary single particle images were obtained. Our results provide guidance for the structural and functional analysis of GPI-TA. 相似文献
110.
X Ding X Feng A Saeki S Seki A Nagai D Jiang 《Chemical communications (Cambridge, England)》2012,48(71):8952-8954
Phthalocyanine covalent organic frameworks with different central metals are synthesized, and the AA-stacking structure of the 2D polymer sheets results in periodic phthalocyanine π-columns. The central metals control the π-electronic functions, including the improvement of light absorbance, the ease of carrier transport, and the photocurrent gain. 相似文献