全文获取类型
收费全文 | 172篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
化学 | 103篇 |
晶体学 | 4篇 |
力学 | 3篇 |
数学 | 10篇 |
物理学 | 56篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 11篇 |
2013年 | 1篇 |
2012年 | 15篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有176条查询结果,搜索用时 15 毫秒
41.
Taweecheep Pornchanok Naloka Kallayanee Matsutani Minenosuke Yakushi Toshiharu Matsushita Kazunobu Theeragool Gunjana 《Applied biochemistry and biotechnology》2019,189(1):144-159
Applied Biochemistry and Biotechnology - High temperature and high ethanol concentrations obviously affect vinegar fermentation. The thermotolerant and ethanol-resistant strains are expected to... 相似文献
42.
43.
A concise total synthesis of xestodecalactone A, utilizing a Diels-Alder strategy is described. The focal Diels-Alder reaction relied on an "ynoate" dienophile to rapidly assemble the required resorcylinic acid scaffold. During this study, Diels-Alder cycloaddition reactions involving 1,3-disubstituted nonequivalent allene dienophiles were studied, and some surprising results were encountered. 相似文献
44.
Yagai S Nakajima T Kishikawa K Kohmoto S Karatsu T Kitamura A 《Journal of the American Chemical Society》2005,127(31):11134-11139
Hydrogen-bonded disk-shaped aggregates (rosettes) composed of azobenzene-appended melamine and barbiturate or cyanurate are investigated in view of their hierarchical organization and photoresponsive behavior by (1)H NMR and UV/vis spectroscopies, dynamic light scattering, and gelation behavior in aliphatic solvents and liquid crystalline behavior in bulk state. In the bulk state the rosette possessing a sterically bulky tridodecyloxyphenyl substituent in the barbiturate component stacks in an offset arrangement to form a rectangular columnar mesophase, whereas in aliphatic solvents it does not hierarchically organize into higher-order columnar aggregates. This drawback is improved by exchanging the barbiturate component into a more sterically nondemanding N-dodecylcyanurate component. The resulting new rosette stacks in a face-to-face arrangement to form a hexagonal columnar mesophase in the bulk state and hierarchically organizes into elongated fibrous aggregates in cyclohexane, which eventually leads to the formation of organogel. Dynamic light scattering and UV-vis experiments upon UV-irradiation of the columnar aggregates in cyclohexane revealed that the dissociation and the reformation of columnar aggregates can be controlled by the trans-cis isomerization of the azobenzene moiety. Molecular modeling indicates that the rosette possessing cis-azobenzene side chains loses its planarity. Using this photoinduced morphological change of the rosette, photoresponsive organogel is created by the use of a disk-shaped supramolecule the first time. 相似文献
45.
The ether extract of the females of white-spotted longicorn beetle Anoplophora malasiaca showed activity as contact sex pheromone to males. The extract was fractionated, and a pheromonal activity was revealed only when three fractions; n-hexane, n-hexane/EtOAc 9:1, and EtOAc were blended. The relative structures of gomadalactone A, B, and C, three active components isolated from the EtOAc fraction, were determined by spectroscopic studies to be (1S∗,4R∗,5S∗)-5-hydroxy-4-[(E)-7-hydroxy-4-methylhept-3-enyl]-4,8-dimethyl-3-oxabicyclo[3.3.0]octan-7-en-2,6-dione, (1R∗,4R∗,5R∗)-5-hydroxy-4-[(E)-7-hydroxy-4-methylhept-3-enyl]-4,8-dimethyl-3-oxabicyclo[3.3.0]octan-7-en-2,6-dione, and (1S∗,4R∗,5S∗,8S∗)-5-hydroxy-4-[(E)-7-hydroxy-4-methylhept-3-enyl]-4,8-dimethyl-3-oxabicyclo[3.3.0]octan-2,6-dione, respectively. 相似文献
46.
Yuichi Hashimoto Toshiharu Ohta Koichi Shudo Toshihiko Okamoto 《Tetrahedron letters》1979,20(18):1611-1614
O-Acetates of 4-hydroxy and 4-hydroxy-7-methoxy-2H-1,4-benzoxazin-3-ones reacted with nucleophiles such as phenols, indoles and ethanethiol. The major reaction center is the positively-charged nitrogen atom. In the reaction with 2-methylindole, 6-position of the benzoxazinone ring is another major reaction center. 相似文献
47.
Keiji Itoh Masashi Sonobe Masaaki Sugiyama Kazuhiro Mori Toshiharu Fukunaga 《Journal of Non》2008,354(2-9):150-154
(Li2S)50(GeS2)50 glass was characterized by high-energy X-ray diffraction. The results were compared with previous neutron diffraction data. Moreover, Reverse Monte Carlo (RMC) modeling was performed using the X-ray and neutron data in order to obtain a three-dimensional structural model. The RMC model showed that the Ge–S framework structure was formed mainly by the connection of corner-sharing GeS4 tetrahedra. Furthermore, many lithium ions were coordinated by three non-bridging sulfurs and one bridging sulfur. 相似文献
48.
49.
Hirata H Itoh T Hosokawa K Deng Y Susaki H 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,175(2):177-184
This article describes a systematic method for determining the cutoff frequency of the low-pass window function that is used for deconvolution in two-dimensional continuous-wave electron paramagnetic resonance (EPR) imaging. An evaluation function for the criterion used to select the cutoff frequency is proposed, and is the product of the effective width of the point spread function for a localized point signal and the noise amplitude of a resultant EPR image. The present method was applied to EPR imaging for a phantom, and the result of cutoff frequency selection was compared with that based on a previously reported method for the same projection data set. The evaluation function has a global minimum point that gives the appropriate cutoff frequency. Images with reasonably good resolution and noise suppression can be obtained from projections with an automatically selected cutoff frequency based on the present method. 相似文献
50.
Takeda Y Yoshino T Uoto K Terasawa H Soga T 《Chemical & pharmaceutical bulletin》2002,50(10):1398-1400
A new method for the synthesis of 7-deoxytaxane analogues has been established through hydrogenation of Delta(6,7)-taxane derivatives. Among several catalysts examined, Pd-C was found to be a most effective catalyst for the preparation of target compound. 相似文献