全文获取类型
收费全文 | 166篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 142篇 |
力学 | 9篇 |
数学 | 2篇 |
物理学 | 16篇 |
出版年
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 1篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 14篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有169条查询结果,搜索用时 281 毫秒
161.
We have reported the degradation of arsenobetaine [(CH3)3As+CH2COO?] to inorganic arsenic by microorganisms from various marine origins such as sediments. However, there was no information as to the fate of the ingested arsenobetaine within the body of the microorganisms before excretion. In this study, arsenobetaine and sediments were added to two culture media (1/5 Zobell 2216E and a solution of inorganic salts) and aerobically incubated at 25°C in the dark. Despite the degradation and complete disappearance of arsenobetaine from the filtrates of the incubation mixtures, the major arsenic compound from the microorganisms harvested from the mixtures was identified by HPLC as arsenobetaine throughout the incubation period. The presence of arsenobetaine was further confirmed by TLC and fast atom bombardment mass spectrometry (FAB MS). A minor arsenical also present in the incubated microorganisms, dimethylarsinic acid, was detected. 相似文献
162.
A Ejima H Terasawa M Sugimori S Ohsuki K Matsumoto Y Kawato H Tagawa 《Chemical & pharmaceutical bulletin》1989,37(8):2253-2255
The camptothecin analogues (+-)-7-ethyl-10-methoxy-20-deoxyaminocamptothecin (2) and (+-)-7-ethyl-10-hydroxy-20-deoxyaminocamptothecin.HCl (3) were synthesized from indolizine compound 4 via Friedl?nder condensation to construct a pentacyclic ring system, and were tested in a P388 mouse antileukemia assay. Compounds 2 and 3 were more active and less toxic than (+)-camptothecin (1), and therefore had higher therapeutic ratios. 相似文献
163.
Imahori H Ueda M Kang S Hayashi H Hayashi S Kaji H Seki S Saeki A Tagawa S Umeyama T Matano Y Yoshida K Isoda S Shiro M Tkachenko NV Lemmetyinen H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(36):10182-10193
We have systematically examined the substituent effects of meso-tetraphenylporphyrins on film structures and the photoelectrochemical properties of the composite clusters of free-base porphyrin and C(60) electrophoretically deposited on nanostructured SnO(2) electrodes. The photocurrent generation efficiency was found to correlate with the complexation ability of the porphyrin for C(60). Basically, the incident photon-to-current efficiency (IPCE) value was increased with increasing relative amounts of the porphyrin versus C(60) in the films. The unique molecular arrangement of the porphyrin with the simple, specific substituents (i.e., methoxy groups at the meta-positions of the meso-phenyl rings of tetraphenylporphyrins (3,5-OMeTPP; TPP=tetraphenylporphyrin)) and C(60) on SnO(2) electrodes resulted in the largest IPCE value (ca. 60 %) among this type of photoelectrochemical device. The rapid formation of the composite clusters and microcrystals from the combination of 3,5-OMeTPP and C(60) in a mixed solvent is unique as the association is accelerated by intermolecular interactions (i.e., hydrogen-bonding and CH-pi interactions) between the methoxy groups of the porphyrins and the porphyrin/C(60), in addition to the pi-pi interactions between the porphyrins/C(60) and C(60) molecules. Both the films and single crystals composed of the porphyrin and C(60) exhibited remarkably high electron mobility (7x10(-2) and 0.4 cm(2) V(-1) s(-1)), which is comparable to the value for highly efficient bulk heterojunction solar cells. Our experimental results have successfully demonstrated the importance of nanostructured electron- and hole-transporting pathways in bulk heterojunction solar cells. Such a finding will provide basic and valuable information on the design of molecular photovoltaics at the molecular level. 相似文献
164.
Nagashima K Yanagida T Tanaka H Seki S Saeki A Tagawa S Kawai T 《Journal of the American Chemical Society》2008,130(15):5378-5382
Heterostructured transition metal oxide nanowires are potential candidates to incorporate rich functionalities into nanowire-based devices. Although the oxide heterointerface plays a crucial role in determining the physical properties, the effects of the heterointerface on the oxide nanowire's properties have not been clarified. Here we investigate for the first time the significant role of the heterointerface in determining the transport properties of well-defined MgO/titanate heterostructured nanowires by combining a technique for in situ formation of a oxide heterointerface and microwave conductivity measurement. Variation of the heterointerface strongly affects the nanowire's transport properties due to the crystallinity and the atomic interdiffusion at the oxide heterointerface. Thus, the precise in situ formation of a well-defined heterointerface is crucial to create oxide heterostructured nanowires with the desired transport properties. 相似文献
165.
The direct formation of multisegment nanowires consisting of polymer domains by ion beam irradiation is investigated. Cross-linking reactions in the ion tracks result in localized gelation, giving isolated nanowires on substrates. It is demonstrated that the morphology of the final nanostructure is customized by appropriate selection of the ion fluence, combination of polymers, and the solvent employed for development. Octopus-like nanostructures consisting of a tangled hydrophilic polymer core and splayed hydrophobic polymer segments are successfully produced as an example of the process. The present technique provides universal feasibility for the formation of nanostructures based on "any" polymer materials in which radiation induces cross-linking reactions. 相似文献
166.
Fratiloiu S Grozema FC Koizumi Y Seki S Saeki A Tagawa S Dudek SP Siebbeles LD 《The journal of physical chemistry. B》2006,110(12):5984-5993
The electronic structure and optical properties of charged oligofluorenes were studied experimentally and theoretically. Measurements of the optical absorption spectra of charged oligofluorenes in dilute solutions have been performed by using the pulse radiolysis technique. In addition, optical absorption spectra of radical cations and anions in a solid matrix were measured after gamma-irradiation at 77 K. The optical absorption spectra were measured in the range of 440-2100 nm (0.6-2.8 eV) and compared with results from time-dependent density functional theory (TDDFT) calculations. The calculated charge induced deformations and charge distribution do not indicate the occurrence of polaronic effects. The potential energy profiles for rotation around the inter-unit bond show that oligofluorenes are nonplanar in their neutral state, while they tend to more planar structures in their charged state. The optical absorption spectra of charged oligofluorenes are dependent on the angle between neighboring units. TDDFT absorption energies shift to lower values with increasing chain length, which suggests that the charge delocalizes along the oligomer chain. 相似文献
167.
Yamagami R Kobayashi K Saeki A Seki S Tagawa S 《Journal of the American Chemical Society》2006,128(7):2212-2213
We report the first direct observation of charge transport dynamics using time-resolved microwave conductivity and transient absorption spectroscopy techniques on the photolysis of an anthraquinone-bound DNA complex. 相似文献
168.
169.
Takuya Hashimoto Kazunari Takagi Kenji Tsuda Michiyoshi Tanaka Kaori Yoshida Hiroaki Tagawa Masayuki Dokiya 《ChemInform》2001,32(10):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献