全文获取类型
收费全文 | 1669篇 |
免费 | 64篇 |
国内免费 | 9篇 |
专业分类
化学 | 1375篇 |
晶体学 | 19篇 |
力学 | 20篇 |
数学 | 112篇 |
物理学 | 216篇 |
出版年
2024年 | 3篇 |
2023年 | 15篇 |
2022年 | 18篇 |
2021年 | 24篇 |
2020年 | 16篇 |
2019年 | 42篇 |
2018年 | 30篇 |
2017年 | 19篇 |
2016年 | 54篇 |
2015年 | 45篇 |
2014年 | 45篇 |
2013年 | 87篇 |
2012年 | 121篇 |
2011年 | 126篇 |
2010年 | 57篇 |
2009年 | 55篇 |
2008年 | 119篇 |
2007年 | 102篇 |
2006年 | 118篇 |
2005年 | 114篇 |
2004年 | 88篇 |
2003年 | 90篇 |
2002年 | 64篇 |
2001年 | 13篇 |
2000年 | 26篇 |
1999年 | 15篇 |
1998年 | 4篇 |
1997年 | 21篇 |
1996年 | 21篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 14篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1985年 | 21篇 |
1984年 | 14篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 16篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1977年 | 8篇 |
1976年 | 17篇 |
1975年 | 11篇 |
1973年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有1742条查询结果,搜索用时 15 毫秒
91.
Dr. Fenghua Ding Atsunori Doi Dr. Takafumi Ogawa Dr. Hiroki Ubukata Dr. Tong Zhu Dr. Daichi Kato Dr. Cédric Tassel Dr. Itaru Oikawa Dr. Naoki Inui Dr. Satoru Kuze Tsutomu Yamabayashi Dr. Kotaro Fujii Prof. Masatomo Yashima Prof. Xing Ou Dr. Zhijian Wang Prof. Xiaobo Min Prof. Koji Fujita Prof. Hitoshi Takamura Prof. Akihide Kuwabara Tianren Zhang Prof. Kent J. Griffith Prof. Zhang Lin Prof. Liyuan Chai Prof. Hiroshi Kageyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(15):e202401779
The Li3MX6 compounds (M=Sc, Y, In; X=Cl, Br) are known as promising ionic conductors due to their compatibility with typical metal oxide cathode materials. In this study, we have successfully synthesized γ-Li3ScCl6 using high pressure for the first time in this family. Structural analysis revealed that the high-pressure polymorph crystallizes in the polar and chiral space group P63mc with hexagonal close-packing (hcp) of anions, unlike the ambient-pressure α-Li3ScCl6 and its spinel analog with cubic closed packing (ccp) of anions. Investigation of the known Li3MX6 family further revealed that the cation/anion radius ratio, rM/rX, is the factor that determines which anion sublattice is formed and that in γ-Li3ScCl6, the difference in compressibility between Sc and Cl exceeds the ccp rM/rX threshold under pressure, enabling the ccp-to-hcp conversion. Electrochemical tests of γ-Li3ScCl6 demonstrate improved electrochemical reduction stability. These findings open up new avenues and design principles for lithium solid electrolytes, enabling routes for materials exploration and tuning electrochemical stability without compositional changes or the use of coatings. 相似文献
92.
Naoki Negishi Kazuhiko Ishihara Isao Shinohara 《Journal of polymer science. Part A, Polymer chemistry》1982,20(7):1907-1916
The hydrophobic interaction of amphiphilic copolymers, which contain 2-hydroxyethyl methacrylate(HEMA) and 1vinyl-2-pyrrolidone (VPy), with Methyl Orange (MO) was compared with that of HEMA-acrylamide (AAm) copolymers to deduce the correlation between their complexation ability in a photochromic azo dye and the photoviscosity effect in aqueous copolymer/dye complex solution. On the basis of the dialysis data and fluorometric analysis it appeared that the complexation dependence on HEMA content in the copolymers was due to the hydrophobic interaction between the polymer and the dye. For a comparable HEMA content AAm copolymers bound less MO than VPy copolymers. It was confiied by photoviscosity measurements that the conformation of the complex composed of photochromic azo dye and HEMA copolymer changed reversibly in response to the photo- and thermal isomerization of the dye. In HEMA-AAm copolymer systems the photoviscosity effect was small compared with that of HEMA-VPy copolymer systems. From these results it was concluded that the complexation ability of polymers due to the hydrophobic interaction was an important factor in producing a large photoinduced conformational change in water. 相似文献
93.
Highly regio-selective cyanation of vicinal (Z)-dibromoalkenyl silanes was achieved by a vinylic Rosenmund-von Braun reaction, significantly suppressing side-production of alkyne. The alkyne was generated by a halogen elimination side-reaction that is an intrinsic problem in metal-activation of vicinal dihaloalkenes. We have studied to overcome the problem, and finally found the combination of CuCN and O = PPh3 in toluene solvent effectively controlled the production of byproducts. The resultant single isomer has significance in potentially application as a multi-tunable synthetic scaffold. 相似文献
94.
95.
The determination of nanometer thick layers of poly(methyl methacrylate) coated on to the surface of poly(ethylene terephthalate) film has been investigated by high resolution pyrolysis gas chromatography without sample pretreatment or modification of the instrumentation used. A good linear relationship was observed between the quantity of the characteristic pyrolysate and the thickness of the poly(methyl methacrylate) layer; the detection limit was sufficient to enable the quantitation of poly(methyl methacrylate)-to-poly(ethylene terephthalate) film thickness ratios of 1:20000 in composite materials. 相似文献
96.
Sainer Siagian Khairul Basar Takashi Sakuma Haruyuki Takahashi Naoki Igawa Yoshinobu Ishii 《Solid State Ionics》2009,180(6-8):480-482
Diffuse neutron scattering from a powder AgCl was measured from 10 to 260 K. The correlation effects among thermal displacements of atoms were obtained from the diffraction data. The values of the correlation effects decrease rapidly with the increase of the inter-atomic distance. The values also decrease with the decrease of temperature. The similar tendency was also obtained in AgBr and CuI. The temperature dependence of the values of correlation effects agrees with the result by a simple Debye model of lattice vibrations. 相似文献
97.
Shin Kikuchi Naoki Kozuka Eiji Uchida Takafumi Ninomiya Haruyuki Tatsumi Hidekatsu Takeda Nobutada Tachi 《Physical Therapy Research》2008,11(1):23-27
Myotonic dystrophy (MyD) is a neuromuscular disease that is autosomal dominant and the most common form of muscular dystrophy affecting adults. The clinical features of MyD include a multisystemic disorder characterized by myotonia, progressive muscle weakness and wasting, cataracts, premature balding and mental retardation. The most severe type of MyD is classified as congenital MyD (CMyD). The muscle weakness in CMyD is very severe, but muscle development can be observed in the period of growth. However, no clinical case of this type has been reported yet. Therefore, we report on a girl with CMyD who had an increase in muscle strength over a four-year period. The girl with CMyD participated in this study from the age of 9 to the age of 12. The measurement of muscle strength was recorded as the maximum score of grip strength with the use of dynamometers. Grip strength was assessed once a year by the same two physical therapists. Grip strength of CMyD for each year was markedly weak when compared with the normal controls, but muscle strength changed within some specific growth areas. The muscle weakness in CMyD was remarkable, but the result showed that specific muscle strength of CMyD in childhood was actually increased. 相似文献
98.
Glyceraldehyde was transformed to threose, erythrose, and erythrose using electro-reduction as key reactions. 相似文献
99.
Kise N 《The Journal of organic chemistry》2004,69(6):2147-2152
The electroreductive cyclization of hept-6-en-2-one, octa-7-en-2-one, and 5-phenylpentan-2-one was investigated by ab initio (UHF/6-311++G**) and density functional (UB3LYP/6-311++G**) calculation methods. The high regio- and stereoselectivities previously reported for olefinic ketones (exo-trans) and 5-arylpentan-2-ones (endo-trans) were reconfirmed. These experimental results well agree with the computational outcome for the transition states in the intramolecular coupling of ketyl radicals generated by one-electron transfer to the ketones. 相似文献
100.
Tanaka Y Hoshino W Shimizu S Youfu K Aratani N Maruyama N Fujita S Osuka A 《Journal of the American Chemical Society》2004,126(10):3046-3047
When heated, bis-Cu(II) octaphyrin(1.1.1.1.1.1.1.1) is quantitatively split into two Cu(II) porphyrins both in solution and film states, which is accompanied by large absorption spectral changes. 相似文献