全文获取类型
收费全文 | 187篇 |
免费 | 5篇 |
专业分类
化学 | 121篇 |
晶体学 | 6篇 |
力学 | 4篇 |
数学 | 19篇 |
物理学 | 42篇 |
出版年
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 14篇 |
2007年 | 14篇 |
2006年 | 14篇 |
2005年 | 10篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有192条查询结果,搜索用时 0 毫秒
161.
Takeshi Fukuda Kouji Fujimoto Mauro M. Murakami Kenji Kawabata Takeaki Miyamoto 《Macromolecular Symposia》1996,101(1):147-155
Three co-operative phenomena that are supposed to originate in the orientation-dependent interactions among polymer segments are discussed and attempted to be interpreted in terms of a common set of polymer models. 相似文献
162.
Kouji Maeda Akira Sonoda Hideo Miki Yusuke Asakuma Keisuke Fukui 《Crystal Research and Technology》2004,39(11):1006-1013
Single potassium dihydrogen phosphate (KDP) crystals were grown in a supersaturated solution containing an organic dye (sunset yellow FCF, brilliant blue FCF, and sky blue). The growth rate, morphology, and impurity dye distribution of faces, (100) and (101) in a KDP crystal were measured as dye concentration and the supersatutation of KDP were changed. Complete expressions for the effect of dye on all aspects of the growth of KDP crystals were discussed. The growth rates of (100) and (101) faces were well correlated by the empirical equation, and resulted in good estimation of the morphology. The distribution of dye in a KDP crystal was represented by the distribution model containing the minimum growth rate for coloring. The growth rate equation and distribution equation were expressed by functions of the supersaturation and dye concentration, and they could effectively provide the operational conditions with coloring the KDP crystal. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
163.
164.
Taku Matsuo Hiroshi Nakamura Hiroshi Sakaguchi Kouji Shimomura Isamu Yoshimatsu Keisuke Takuma 《Molecular Crystals and Liquid Crystals》2013,570(2):185-196
Remarkable electric field effects were observed with sensitized fluorescence intensities of a perylene derivative (BPDC), when rectangular AC waves (up to 10 V0-p ) were applied to nematic liquid crystal cells containing a sensitizer (C307 or AHDA) and an acceptor (BPDC) as the guest molecules. Measurements of the fluorescence lifetime of AHDA indicated that the rates of energy transfer from AHDA to BPDC were independent of the electric fields. The electric field effects completely changed the sign when the intensity variation detected at vertical direction was compared with that at the horizontal direction with respect to the liquid crystal cell. The observed electric field effects on the sensitized fluorescence were consequently suggested to come from the orientation control of transition dipole moment of BPDC through the molecular alignment of the liquid crystal. The suggestion was confirmed by the measurement of dichroic absorption of the donor-acceptor systems. 相似文献
165.
Shoma Mizutani Kenta Komori Prof. Dr. Tohru Taniguchi Prof. Dr. Kenji Monde Prof. Dr. Kouji Kuramochi Prof. Dr. Kazunori Tsubaki 《Angewandte Chemie (International ed. in English)》2016,55(33):9553-9556
A biomimetic synthesis of naturally occurring lactams rubrobramide, flavipucine, and isoflavipucine is described. The key step is a regioselective Darzens reaction between isobutyl glyoxal and an α‐bromo‐β‐ketoamide. The construction of the core tricyclic ring system of rubrobramide was achieved by a cascade reaction in a single step from an α,β‐epoxy‐γ‐lactam. Furthermore, the absolute configuration of naturally occurring (+)‐rubrobramide was determined by vibrational circular dichroism. (±)‐Flavipucine and (±)‐isoflavipucine were synthesized from an epoxyimide, which was prepared by reaction of isobutyl glyoxal with a protected α‐bromo‐β‐ketoamide. Deprotection of the epoxyimide and formation of the pyridone ring gave (±)‐flavipucine, which was converted into (±)‐isoflavipucine by thermal isomerization. 相似文献
166.
Suemori Y Fujii K Ogawa M Nakamura Y Shinohara K Nakagawa K Nagata M Iida K Dewa T Yamashita K Nango M 《Colloids and surfaces. B, Biointerfaces》2007,56(1-2):182-Optics
Bacterial photosynthetic membrane proteins, light-harvesting antenna complex (LH1), reaction center (RC), and their combined ‘core’ complex (LH1–RC) are functional elements in the primary photosynthetic events, i.e., capturing and transferring light energy and subsequent charge separation. These photosynthetic units (PSUs) isolated from Rhodospirillum rubrum (Rs. rubrum) were assembled onto an ITO electrode modified with 3-aminopropyltriethoxysilane (APS–ITO). The near IR absorption spectra of PSUs on the assembled electrodes were identical to those of solutions, indicating that the LH1 and LH1–RC core complexes were native on the electrode. Photocurrent response of PSUs on the electrode was examined upon illumination of the LH1 complex at 880 nm. The LH1–RC and a mixed assembly of LH1 and RC exhibited photocurrent response, but not LH1 only, consistent with the function of these PSUs, capturing light energy and transferring electron. This result provides useful methodology for building an artificial fabrication of PSUs on the electrode. 相似文献
167.
168.
Tanaka SY Tagashira N Chiba K Yasuda M Baba A 《The Journal of organic chemistry》2008,73(16):6312-6320
A highly practical reductive cross-aldol reaction of alpha-bromoaldehydes with various aldehydes has been developed using Ge(II)Cl 2 to produce aldehyde germanium(IV) aldolates, which were directly transformed to various multifunctionalized compounds. A remarkable change in stereoselectivity depended on the alpha-bromoaldehydes employed; secondary alpha-bromoaldehydes gave syn selectivities, while tertiary alpha-bromoaldehydes accomplished the synthesis of anti-selective aldol products with a quaternary carbon center. NMR studies and X-ray analysis strongly suggested the formation of germanium enolate in the reaction of alpha-bromoaldehyde 2h with GeCl 2-dioxane. Detailed mechanistic studies, including NMR analysis and ab initio calculations, revealed the generation of stable germanium aldolates, which was due to the remarkably low Lewis acidity of the germanium(IV). 相似文献
169.
Daigo Matsumoto Akira KotaniHideki Hakamata Kouji TakahashiFumiyo Kusu 《Journal of chromatography. A》2010,1217(17):2986-2989
Column switching HPLC with electrochemical detection (HPLC-ED), which consists of one pre-column and two electrochemical detectors subsequent to each analytical column, called HPLC-2ED, has been developed for determining isoflavones (daidzin, genistin, daidzein, and genistein) with high sensitivity. In the present HPLC-2ED, the eluted daidzin and genistin from the pre-column were separated on an analytical column using a methanol–water–phosphoric acid mixture (30:70:0.5) as the mobile phase (MP), and daidzein and genistein were separated on another analytical column using a methanol–water–phosphoric acid mixture (50:50:0.5). The way of the elute flow from the pre-column was changed by rotating the switching valve at 17 min. The difference in retention times of genistein between isocratic HPLC-ED and HPLC-2ED was 52.2 min. The detection limit (S/N = 3) per column injection (5 μL) of genistein was 0.5 pg. The sensitivity by the present method is superior to that of previously reported gradient HPLC-ED for the determination of isoflavones. 相似文献
170.
T Takeuchi Y Mizushina S Takaichi N Inoue K Kuramochi S Shimura Y Myobatake Y Katayama K Takemoto S Endo S Kamisuki F Sugawara 《Organic letters》2012,14(17):4303-4305
The total synthesis of (+)-Sch 725680, a member of the hydrogenated azaphilone family, has been accomplished. The synthesis confirmed the absolute configuration and biological activities of the natural product. A key reaction to construct a hydrogenated azaphilone core skeleton is a Ti-mediated aldol reaction. 相似文献