全文获取类型
收费全文 | 357篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 310篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 16篇 |
物理学 | 39篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 26篇 |
2011年 | 33篇 |
2010年 | 19篇 |
2009年 | 9篇 |
2008年 | 27篇 |
2007年 | 30篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 26篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有367条查询结果,搜索用时 15 毫秒
81.
Bo Zhu Yong He Naoki Asakawa Naoko Yoshie Haruo Nishida Yoshio Inoue 《Macromolecular rapid communications》2005,26(8):581-585
Summary: A new crystal morphology (δ form) of poly(3‐hydroxypropionate) (PHP) is found in cast and melt‐crystallized PHPs with low molecular weight, in which the PHP chains possibly adopt a 21 helix rather than the trans conformation found in the β or γ form. The fusion temperature‐ and the crystallization temperature‐dependent polymorphism are responsible for the dual morphologies and the unique growth kinetics of spherulites in the melt‐crystallized PHPs.
82.
We have prepared a hydrophilic molecularly imprinted polymer (MIP) for the hydrophobic compound bisphenol A (BPA) in aqueous solution using 3-acrylamido-N,N,N-trimethylpropan-1-aminium chloride (AMTC) as the functional monomer. Under redox-polymerization conditions, BPA forms an ion-pair with AMTC, which was confirmed by 1H-NMR titration. The imprinting effect in aqueous solution was evaluated by comparison of this material with the corresponding non-imprinted polymer (NIP) and with a control polymer (CP) bearing no AMTC. The MIP showed the highest activity among the three polymers, and the imprinting factors as calculated from the amount of BPA bound to the MIP divided by the amounts bound to NIP and CP, respectively, are 1.8 and 6.0. The MIP was selective for BPA in aqueous solution, while structurally related compounds are not recognized. Such a selectivity for a hydrophobic compound is rarely observed in aqueous medium because non-specific binding of BPA inevitably leads to hydrophobic interaction. Figure
A hydrophilic molecularly imprinted polymer (MIP) for bisphenol A (BPA) recognition was prepared in aqueous solution. The obtained MIP (BPA-MIP) showed good selectivity under aqueous conditions 相似文献
83.
Naoko Asakuma Hiroshi Hirashima Hiroaki Imai Toshimi Fukui Motoyuki Toki 《Journal of Sol-Gel Science and Technology》2003,26(1-3):181-184
Structural changes in sol-gel films with photo-irradiation were investigated using zinc oxide (ZnO) derived from zinc acetate. The exposure of the films to an ultraviolet lamp induced hexagonal ZnO crystals in a relatively dense amorphous structure. On the other hand, the formation of zinc metal was found in a porous gel film. The photo-induced crystallization and reduction are ascribed to the electronic excitation in the metastable non-crystalline states. 相似文献
84.
[reaction: see text] A 2-(2,6-diisopropylphenyl)iminomethylpyridine (1a)/CoCl(2).6H(2)O/Zn reagent has been developed as an effective instant catalyst for the intra- and intermolecular cyclotrimerization of alkynes to substituted benzenes, making the method extremely practical since the reagent, 1a/CoCl(2).6H(2)O/Zn, is inexpensive and easy to handle and the reaction is less sensitive to moisture and is reasonably general. 相似文献
85.
Nakanishi T Miyashita N Michinobu T Wakayama Y Tsuruoka T Ariga K Kurth DG 《Journal of the American Chemical Society》2006,128(19):6328-6329
Fullerene derivatives bearing long alkyl chains epitaxially adsorb on the basal plane of graphite forming well-ordered one-dimensional lamellae. Within the lamellae, the C60 moieties are organized in a zigzag-type fashion. The ordering is mainly governed by the substitution pattern and chain length of the alkyl chains. The electrochemical activity of the C60 groups is fully maintained in the surface-confined assemblies. 相似文献
86.
Sakai-Kato K Kato M Nakajima T Toyo'oka T Imai K Utsunomiya-Tate N 《Journal of chromatography. A》2006,1111(2):127-132
Positively charged starch derivatives were used to modify the inner surface of fused-silica capillaries by addition to running buffer, which were subsequently employed in capillary electrophoresis (CE). Capillaries coated with the cationic starch derivatives were shown to generate a stable, reversed electroosmotic flow (EOF) in the investigated pH range of 3-9. The presented coating procedure was fast, based on a simple rinsing protocol where the polymer created a physically adsorbed, cationic polymer layer. Among the additives studied, a quaternary ammonium starch derivative showed a fast EOF mobility and effectively suppressed the adsorption of proteins. The intra- and inter-day reproducibility of the coating referring to the EOF mobility were satisfactory with relative standard deviation (RSD) of 0.27 and 1.67%, respectively. The coating enabled separation of some protein mixtures including basic proteins within l3 min with efficiencies up to 280,000 plates/m. In addition, this cationic starch derivative possessed a good solubility (about 100mg/mL), and it does not significantly contribute to the background adsorption in the UV region of 190-400 nm. 相似文献
87.
Kobayashi S Shinohara H Tabata K Yamamoto N Miyai A 《Chemical & pharmaceutical bulletin》2006,54(12):1633-1638
The aim of this study was to elucidate the structure-activity relationship of bisphenol A (BPA) analogs using absolute hardness (eta) and absolute electronegativity (chi) (chemical hardness) and to design a non-estrogen active BPA. To determine the structure-activity relationships of BPA analogs, we investigated MCF-7 cell proliferation stimulated by BPA analogs and an eta-chi diagram based on the electronic structure of the BPA analogs. The results show that the actions of the environmental hormones BPA analogs have two chemical properties; (i) 'stereo structure-controlled' and (ii) 'electronic structure-controlled' estrogen-like chemical activities. Therefore, we designed and synthesized BPA analogs which do not possess these 2 characteristics, ((i) and (ii)), and demonstrate the non-estrogen activity of the analog. 相似文献
88.
Xin Huang Shintaro Nakagawa Xiang Li Mitsuhiro Shibayama Naoko Yoshie 《Angewandte Chemie (International ed. in English)》2020,59(24):9646-9652
Polymer networks usually contain numerous inhomogeneities that deteriorate their physical properties and should be eliminated to create reliable, high‐performance materials. A simple method is introduced for the production of nearly ideal networks from various vinyl polymers through controlled polymerization and subsequent crosslinking. Monodisperse star polymers with bromide end groups were synthesized by atom‐transfer radical polymerization and end‐linked with dithiol linkers using thiol–bromide chemistry. This simple procedure formed nearly ideal polymer networks, as revealed from elasticity of the formed gel and model conjugation reactions involving linear polymers. The versatility of this method was demonstrated by preparing networks of common vinyl polymers, including polyacrylates, polymethacrylate, and polystyrene. This method can be used to prepare multiple functional nearly ideal gels and elastomers and to explore fundamental aspects of polymer networks. 相似文献
89.
Adsolubilization of 2-naphthol into an adsorbed layer of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers (Pluronics) on hydrophilic silica has been investigated. Four kinds of Pluronics (P103, P105, P123, and F108) were used in order to understand the effect of the hydrophobicity of surfactant on the adsolubilization. The order of the adsorption in the saturation level was found to be P123 approximately P103 > P105 > F108, meaning that Pluronics with higher hydrophobicity can adsorb preferentially to the silica surface. Indeed, this order was parallel to the order of the adsolubilization amount of 2-naphthol. In the case of co-addition of the Pluronics and 2-naphthol, the adsolubilization amount increased gradually at lower surfactant concentration regions, reached a maximum, and then decreased with increasing concentration of the Pluronics. The maximum amount appeared at critical polymolecular micelle concentration of each Pluronics. On the other hand, the final decrement was not observed when 2-naphthol was added after replacement of the Pluronics supernatant by the Pluronics free solution. These results suggest that adsolubilization behavior is influenced by the existence of the polymolecular micellar aggregates in the solution phase. 相似文献
90.
Organocatalytic direct asymmetric aldol reactions in water 总被引:2,自引:0,他引:2
Mase N Nakai Y Ohara N Yoda H Takabe K Tanaka F Barbas CF 《Journal of the American Chemical Society》2006,128(3):734-735
We have developed direct asymmetric cross-aldol reactions that can be performed in water without addition of organic solvents. A bifunctional catalyst with a long hydrophobic alkyl chain efficiently catalyzed the reactions and afforded the desired aldol products in excellent yield with high enantiomeric excess, even when only an equal molar ratio of the donor and acceptor was used. These results reveal an effective design strategy for the development of aqueous organocatalytic systems. 相似文献