全文获取类型
收费全文 | 657篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
化学 | 554篇 |
晶体学 | 17篇 |
力学 | 4篇 |
数学 | 19篇 |
物理学 | 91篇 |
出版年
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 7篇 |
2016年 | 14篇 |
2015年 | 13篇 |
2014年 | 12篇 |
2013年 | 20篇 |
2012年 | 39篇 |
2011年 | 52篇 |
2010年 | 16篇 |
2009年 | 26篇 |
2008年 | 40篇 |
2007年 | 49篇 |
2006年 | 40篇 |
2005年 | 35篇 |
2004年 | 49篇 |
2003年 | 25篇 |
2002年 | 32篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有685条查询结果,搜索用时 0 毫秒
181.
Dr. Feng Dang Dr. Yuya Oaki Takao Kokubu Dr. Eiji Hosono Dr. Haoshen Zhou Prof. Dr. Hiroaki Imai 《化学:亚洲杂志》2013,8(4):760-764
Nanoporous MnO frameworks with highly dispersed Co nanoparticles were produced from MnCO3 precursors prepared in a gel matrix. The MnO frameworks that contain 20 mol % Co exhibited excellent cycle performance as an anode material for Li‐ion batteries. The solid–electrolyte interphase (SEI) formed in the frameworks through the electrochemical reaction mediates the active materials, such as MnO, Mn, and Li2O, during the conversion reaction in the charge–discharge cycle. The Co nanoparticles and SEI provide the electron and Li‐ion conductive networks, respectively. The ternary nanocomposites of the MnO framework, metallic Co nanoparticles, and embedded SEI are categorized as durable anode materials for Li‐ion batteries. 相似文献
182.
Prof. Hiroki Taniguchi Dr. Akihide Kuwabara Dr. Jungeun Kim Younghun Kim Dr. Hiroki Moriwake Prof. Sungwng Kim Takuya Hoshiyama Tsukasa Koyama Prof. Shigeo Mori Prof. Masaki Takata Prof. Hideo Hosono Prof. Yoshiyuki Inaguma Prof. Mitsuru Itoh 《Angewandte Chemie (International ed. in English)》2013,52(31):8088-8092
183.
Yoshioka Y Kawai H Sato T Yamaguchi K Saito I 《Journal of the American Chemical Society》2003,125(7):1968-1974
The G-selectivity for Cu(I)-mediated one-electron oxidation of 5'-TG(1)G(2)G(3)-3' and 5'-CG(1)G(2)G(3)-3' has been examined by ab initio molecular orbital calculations. It was confirmed that G(1) is selectively damaged by Cu(I) ion for both 5'-TG(1)G(2)G(3)-3' and 5'-CG(1)G(2)G(3)-3', being good agreement with experimental results. The Cu(I)-mediated G(1)-selectivity is primarily due to the stability of the Cu(I)-coordinated complex, [-XG(1)G(2)G(3)-,-Cu(I)(H(2)O)(3)](+). The Cu(I) ion coordinates selectively to N7 of G(2) of 5'-G(1)G(2)G(3)-3' rather than N7 of G(1). The G(2)-selective coordination induces the G(1)-selective trap of a hole that is created by one-electron oxidation and migrates to GGG triplet. Therefore, the radical cation of G(1) is selectively created in both 5'-TG(1)G(2)G(3)-3' and 5'-CG(1)G(2)G(3)-3', giving the G(1)-selective damage of 5'-G(1)G(2)G(3)-3'. 相似文献
184.
Nobuhiro Anzai Hiroko Kurihara Masato Sone Hidemitsu Furukawa Toshiyuki Watanabe Kazuyuki Horie Sandeep Kumar 《Liquid crystals》2006,33(6):671-679
We have found that the discotic nematic liquid crystal, hexakis(4-nonylphenylethynyl)benzene (HNEB), doped with the racemic chromium complex Cr(Ocacac)3, shows a novel straight-needle texture with hexagonal columnar alignments, changing to a curved-needle texture under irradiation of circularly polarized light (CPL). This novel phenomenon is specific to the mixture of HNEB and Cr(Ocacac)3. The formation of curved needles means that chiroselective photoinversion of racemic Cr(Ocacac)3 by CPL irradiation induces a needle direction change in a discotic liquid crystal. The change in chirality of Cr(Ocacac)3 in HNEB induced by CPL irradiation, and the resulting nano-segregation of its enantiomers during cooling from the isotropic to mesophase of HNEB, are considered to influence changes in the alignment of columns and/or small domains of column aggregates in the discotic liquid crystal. 相似文献
185.
Poly (4-vinyl phenol) (P4VPh) gels were prepared by crosslinking with a hydrophilic crosslinker [ethyleneglycoldiglycidylether (EGDGE)] and a hydrophobic one [diglycidyl 1,2-cyclohexane dicarboxylate (DGCHDC)], and the former gel was further modified by CH3I or C2H5I to partially convert the hydrogen of phenol OH to the corresponding alkyl groups. Swelling behaviors of P4VPh gels, thus modified, were investigated to see how the hydrophobic groups introduced to the crosslinker and the polymer substrate affect the super salt resistivity to inorganic ions and the high water content (>90%) that have been observed for the original P4VPh gel. Water content and salt resistivity were unexpectedly preserved even for the modified gels. Effects of the chemical modifications on the gel swelling were only observed in the presence of hydrophobic solutes, i.e., tetrabutyl ammonium chloride and ionic surfactants. All these results strongly suggest that hydration around the polymer substrate in the gel phase is specifically stabilized, probably because of the coexistence of the hydrophobic hydration and the π-hydrogen-bonding hydration around the phenol ring. 相似文献
186.
Hiroko Nakayama Kanae Hata Izumi Matsuoka Liqing Zang Youngil Kim Djongchi Chu Lekh Raj Juneja Norihiro Nishimura Yasuhito Shimada 《Molecules (Basel, Switzerland)》2020,25(24)
(1) Background: The obesity epidemic has been drastically progressing in both children and adults worldwide. Pharmacotherapy is considered necessary for its treatment. However, many anti-obesity drugs have been withdrawn from the market due to their adverse effects. Instead, natural products (NPs) have been studied as a source for drug discovery for obesity, with the goal of limiting the adverse effects. Zebrafish are ideal model animals for in vivo testing of anti-obesity NPs, and disease models of several types of obesity have been developed. However, the evidence for zebrafish as an anti-obesity drug screening model are still limited. (2) Methods: We performed anti-adipogenic testing using the juvenile zebrafish obesogenic test (ZOT) and mouse 3T3-L1 preadipocytes using the focused NP library containing 38 NPs and compared their results. (3) Results: Seven and eleven NPs reduced lipid accumulation in zebrafish visceral fat tissues and mouse adipocytes, respectively. Of these, five NPs suppressed lipid accumulation in both zebrafish and 3T3-L1 adipocytes. We confirmed that these five NPs (globin-digested peptides, green tea extract, red pepper extract, nobiletin, and Moringa leaf powder) exerted anti-obesity effects in diet-induced obese adult zebrafish. (4) Conclusions: ZOT using juvenile fish can be a high-throughput alternative to ZOT using adult zebrafish and can be applied for in vivo screening to discover novel therapeutics for visceral obesity and potentially also other disorders. 相似文献
187.
Elucidation of codoping effects on the solubility enhancement of Er3+ in SiO2 glass: striking difference between Al and P codoping 总被引:1,自引:0,他引:1
Saitoh A Matsuishi S Se-Weon C Nishii J Oto M Hirano M Hosono H 《The journal of physical chemistry. B》2006,110(15):7617-7620
The codoping effect mechanism of Al and P on the solubility enhancement of Er(3+) ion in SiO(2) glass was clarified by electron spin-echo envelope modulation spectroscopy. It turned out that doped P ions preferentially coordinate to the Er(3+) ion to form a "solvation shell structure", and the environment is similar to that in phosphate glass, while doped Al ions do not form such a selective solvation structure, taking octahedral coordination. This striking difference indicates that the primary roles of the P-doping and the Al-doping are attributed to "enthalpy of mixing" and to "entropy of mixing", respectively. 相似文献
188.
An interstitial hydroxyl radical (HO*) has been generated in bulk amorphous SiO2 (a-SiO2) loaded with interstitial H2O molecules and exposed to F2 laser light (hnu = 7.9 eV, lambda = 157 nm) at 77 K. F2 laser light dissociates an O-H bond of interstitial H2O into a pair of hydrogen atom (H0) and HO*. The resultant H0 disappears below 150 K, whereas HO* is detectable after thermal annealing at 200 K. The electron paramagnetic resonance (EPR) signal of the interstitial HO* recorded at 77 K is similar to that formed in amorphous ice, indicating that HO* is confined in an orthorhombic field by hydrogen bonding, probably with adjacent H2O molecules, silanol (SiOH) groups, and bridging oxygen atoms in the a-SiO2 network. 相似文献
189.
Masaaki Suzuki Hisashi Doi Hiroko Koyama Zhouen Zhang Takamitsu Hosoya Hirotaka Onoe Yasuyoshi Watanabe 《Chemical record (New York, N.Y.)》2014,14(3):516-541
Positron emission tomography is a noninvasive method for monitoring drug (or diagnostic) behavior and its localization on the target molecules in the living systems, including the human body, using a short‐lived positron‐emitting radionuclide. New methodologies for introducing representative short‐lived radionuclides, 11C and 18F, into the carbon frameworks of biologically active organic compounds have been established by developing rapid C‐[11C]methylations and C‐[18F]fluoromethylations using rapid Pd0‐mediated cross‐coupling reactions between [11C]methyl iodide (sp3‐hybridized carbon) and an excess amount of organotributylstannane or organoboronic acid ester having sp2(phenyl, heteroaromatic, or alkenyl), sp(alkynyl), or sp3(benzyl and cinnamyl)‐hybridized carbons; and [18F]fluoromethyl halide (iodide or bromide) and an organoboronic acid ester, respectively. These rapid reactions provide a firm foundation for an efficient and general synthesis of short‐lived 11C‐ or 18F‐labeled PET molecular probes to promote in vivo molecular imaging studies. 相似文献
190.
The hydrogen-bonded clusters of 2-fluoropyridine with water were studied experimentally in a supersonic free jet and analyzed with molecular orbital calculations. The IR spectra of 2-fluoropyridine-(H2O)(n) (n = 1 to 3) clusters were observed with a fluorescence detected infrared depletion (FDIR) technique in the OH and CH stretching vibrational regions. The frequencies of OH stretching vibrations show that water molecules bond to the nitrogen atom of 2-fluoropyridine in the clusters. The hydrogen-bond formation between aromatic CH and O was evidenced in the 1:2 and 1:3 clusters from the experimental and calculated results. The overtone vibrations of the OH bending mode in hydrogen-bonded water molecules appear in the IR spectra, and these frequencies become higher with the increase of the number of water molecules in the clusters. The band structure of the IR spectra in the CH stretching region changes depending on the number of coordinating water molecules. 相似文献