全文获取类型
收费全文 | 386篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 285篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 16篇 |
物理学 | 83篇 |
出版年
2022年 | 4篇 |
2021年 | 8篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 23篇 |
2012年 | 20篇 |
2011年 | 18篇 |
2010年 | 13篇 |
2009年 | 16篇 |
2008年 | 20篇 |
2007年 | 27篇 |
2006年 | 19篇 |
2005年 | 14篇 |
2004年 | 17篇 |
2003年 | 14篇 |
2002年 | 14篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 12篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1938年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有389条查询结果,搜索用时 15 毫秒
91.
Masaaki Ohba Dr. Ko Yoneda Gloria Agustí M. Carmen Muñoz Prof. Dr. Ana B. Gaspar Dr. José A. Real Prof. Dr. Mikio Yamasaki Dr. Hideo Ando Yoshihide Nakao Dr. Shigeyoshi Sakaki Prof. Dr. Susumu Kitagawa Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(26):4767-4771
The ins and outs of spin : Using the microporous coordination polymer {Fe(pz)[Pt(CN)4]} ( 1 , pz=pyrazine), incorporating spin‐crossover subunits, two‐directional magnetic chemo‐switching is achieved at room temperature. In situ magnetic measurements following guest vapor injection show that most guest molecules transform 1 from the low‐spin (LS) state to the high‐spin (HS) state, whereas CS2 uniquely causes the reverse HS‐to‐LS transition.
92.
Masaaki Ohba Ko Yoneda Gloria Agustí M.Carmen Muoz AnaB. Gaspar JosA. Real Mikio Yamasaki Hideo Ando Yoshihide Nakao Shigeyoshi Sakaki Susumu Kitagawa 《Angewandte Chemie (International ed. in English)》2009,48(26):4652-4652
Bidirectional chemo‐switching of magnetism occurs in a microporous coordination polymer containing spin‐crossover subunits, as described by M. Ohba, J. A. Real, S. Kitagawa, and co‐workers in their Communication on page 4767 ff. In situ magnetic measurements reveal that most guest molecules transform the framework spin state from diamagnetic low spin (red) to paramagnetic high spin (yellow), whereas the guest CS2 stabilizes the low‐spin state. These induced spin states are retained as a memory effect after the release of the guest.
93.
Dowden J Berridge G Moreau C Yamasaki M Churchill GC Potter BV Galione A 《Chemistry & biology》2006,13(6):659-665
Nicotinic acid adenine dinucleotide phosphate (NAADP, 1) is the most potent intracellular Ca2+ mobilizing agent in important mammalian cells and tissues, yet the identity of the NAADP receptor is elusive. Significantly, the coenzyme NADP is completely inactive in this respect. Current studies are restricted by the paucity of any chemical probes beyond NAADP itself, and importantly, none is cell permeant. We report simple nicotinic acid-derived pyridinium analogs as low molecular weight compounds that (1) inhibit Ca2+ release via the NAADP receptor (IC50 approximately 15 microM - 1 mM), (2) compete with NAADP binding, (3) cross the cell membrane of sea urchin eggs to inhibit NAADP-evoked Ca2+ release, and (4) selectively ablate NAADP-dependent Ca2+ oscillations induced by the external gastric peptide hormone agonist cholecystokinin (CCK) in murine pancreatic acinar cells. 相似文献
94.
Calculations employing the local density approximation combined with static and dynamical mean field theories (LDA+U and LDA+DMFT) indicate that the metal-insulator transition observed at 32 GPa in paramagnetic LaMnO3 at room temperature is not a Mott-Hubbard transition, but is caused by orbital splitting of the majority-spin eg bands. For LaMnO3 to be insulating at pressures below 32 GPa, both on-site Coulomb repulsion and Jahn-Teller distortion are needed. 相似文献
95.
Tetsuya Kida Atsunori Yamasaki Noboru Yamazoe 《Journal of solid state chemistry》2010,183(10):2426-2431
We carried out the partial substitution of the B-site in BaFeO3−δ perovskite with divalent cations to develop novel oxygen-permeable materials. We demonstrated that the partial substitution of Cu or Ni by more than 10% resulted in the stabilization of the cubic perovskite structure even at room temperature in a highly oxygen-permeable phase, as revealed by the X-ray diffraction (XRD) analysis. The Cu substitution was more effective for the stabilization, because the introduction of Cu in the lattice more effectively made the Goldschmidt tolerance factor (t) close to 1.0. Ni- and Cu-substituted BaFeO3−δ membranes showed higher oxygen permeabilities than their parent BaFeO3−δ membranes particularly at lower temperatures around 600-700 °C owing to the stabilization of the cubic phase. Among the fabricated membranes, a BaFe0.85Cu0.15O3−δ membrane (1.0 mm thickness) showed the highest oxygen permeation flux (1.8 cm3 min−1 cm−2 at 930 °C) under an air/He gradient. The results indicated that Cu-substituted BaFeO3-δ is promising as a material for Co-free membranes with high oxygen permeabilities. 相似文献
96.
97.
Satoshi Yamasaki Daisuke Nishiguchi Ken Kojio Mutsuhisa Furukawa 《Journal of Polymer Science.Polymer Physics》2007,45(7):800-814
The effects of the dynamic polymerization method and temperature on the molecular aggregation structure and the mechanical and melting properties of thermoplastic polyurethanes (TPUs) were successfully clarified. TPUs were prepared from poly (ethylene adipate) glycol (Mn = 2074), 4,4′‐diphenylmethane diisocyanate and 1,4‐butanediol by the one‐shot (OS) and the prepolymer (PP) methods in bulk at dynamic polymerization temperatures ranging from 140 to 230 °C. Glass‐transition temperatures (Tgs) of the soft segment and melting points (Tms) of the hard segment domains of OS‐TPUs increased and decreased, respectively, with increasing polymerization temperatures, but those of PP‐TPUs were almost independent of the polymerization temperature. Tgs of the soft segment and Tms of the hard segment domains of these TPUs polymerized above 190 °C were almost the same regardless of the polymerization method. Solid‐state nuclear magnetic resonance spectroscopy (NMR) analyses of OS‐ and PP‐TPUs showed that the relative proton content of fast decay components, which corresponds to the hard segment domains, in these TPUs decreased with increasing polymerization temperatures. These results clearly show that the degree of microphase separation becomes weaker with increasing polymerization temperatures. The temperature dependence of dynamic storage modulus and loss tangent of OS‐TPUs coincided with those of PP‐TPUs at polymerization temperature above 190 °C. The apparent shear viscosity for OS‐ and PP‐TPUs polymerized above 190 °C approached a Newtonian behavior at low shear rates regardless of the polymerization method. These results indicate that TPUs polymerized at higher temperatures form almost the same molecular aggregation structures irrespective of the dynamic polymerization method. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 800–814, 2007 相似文献
98.
The reaction of excited oxygen atom, O(1D2), with propylene has been studied under helium pressure up to 150 atm. The identified oxides and their limiting fractional yields are as follows: propylene oxide 0.22, propionaldehyde 0.22, acetone 0.11, allylalcohol 0.20, acrolein 0.02 and acetaldehyde 0.06. The mechanism of primary attack of O(1D2) on olefin is inferred on the basis of these figures. 相似文献
99.
Edna N. Yamasaki 《European Polymer Journal》2003,39(3):609-616
Linear homopolymers and randomly cross-linked homopolymer networks of 2-(dimethylamino)ethyl methacrylate of various molecular weights (MWs) were synthesized by group transfer polymerization in the bulk. 1-methoxy-1-(trimethylsiloxy)-2-methyl propene was used as the initiator, while tetrabutylammonium bibenzoate served as the catalyst. Ethylene glycol dimethacrylate was the cross-linker used for the network synthesis at an 8-fold molar excess with respect to the initiator. Gel permeation chromatography in tetrahydrofuran was used to characterize the linear homopolymers in terms of their MW and molecular weight distribution (MWD). Although the experimental MWs did not match the theoretical MWs, they were reasonably close to them. The MWDs were rather broad with polydispersity indices ranging between 1.5 and 1.9. The monomer conversion was relatively high, ranging from 97% to 74% for theoretical degrees of polymerization (DPs) from 5 to 500. No polymerization was observed for an attempted DP of 1000. Networks with molar ratios of monomer to initiator (nominal DPs) from 5 to 200 were prepared, while an attempted synthesis with a nominal DP of 500 did not yield a network. The networks were characterized in terms of their degree of swelling in water and the effects of DP, pH, salt concentration and temperature were investigated. 相似文献
100.
Yoshitake Y Misaka J Abe M Yamasaki M Eto M Harano K 《Organic & biomolecular chemistry》2003,1(7):1240-1249
Carboxylic acid host compounds (3) having a phenanthrene-condensed bicyclo[2.2.1]hept-2-en-7-one skeleton have been synthesized by the [4 + 2]pi cycloaddition of phencyclone (1a) with 2-alkenoic acids (2) and their inclusion behavior was investigated. The endo [4 + 2]pi cycloadducts (3) enclathrated alcohols and ethers besides aromatics and ketones. The X-ray crystallographic analysis of the inclusion compound (3ac-dioxane) of the endo [4 + 2]pi cycloadduct (3ac) of phencyclone and trans 2-butenoic acid (2c) indicated that dioxanes are located at the opposite side of the bridged carbonyl of the bicyclo[2.2.1]hept-2-en-7-one moiety, in which the O-H...O and C-H...O hydrogen bonds play an important role in the inclusion complex formation. Similarly, a pair of 3-pentanone molecules were included in the endo [4 + 2] pi cycloadduct (3ae) of 1a and cinnamic acid (2e). In both cases, the hosts are linked by the edge-to-face interaction between the phenanthrene and phenyl rings and the "bidentate" C-H...O hydrogen bonds between the phenanthrene-ring hydrogens and the bridged carbonyl or the carboxylic carbonyl group. The endo [4 + 2] pi cycloadduct (3bl) of tetracyclone (1b) and acrylamide (2l) also showed a wide-range inclusion behavior, in which alcohols are included by making a hydrogen-bond loop with the amide groups. The inclusion behavior of the carboxylic acid Diels-Alder hosts is discussed on the basis of the single crystal X-ray analysis, thermal analysis and semiempirical molecular orbital calculation data. 相似文献