全文获取类型
收费全文 | 1571篇 |
免费 | 94篇 |
国内免费 | 3篇 |
专业分类
化学 | 1214篇 |
晶体学 | 19篇 |
力学 | 21篇 |
数学 | 57篇 |
物理学 | 357篇 |
出版年
2023年 | 17篇 |
2022年 | 18篇 |
2021年 | 35篇 |
2020年 | 27篇 |
2019年 | 40篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 38篇 |
2015年 | 43篇 |
2014年 | 53篇 |
2013年 | 76篇 |
2012年 | 89篇 |
2011年 | 98篇 |
2010年 | 58篇 |
2009年 | 45篇 |
2008年 | 98篇 |
2007年 | 91篇 |
2006年 | 70篇 |
2005年 | 78篇 |
2004年 | 56篇 |
2003年 | 44篇 |
2002年 | 42篇 |
2001年 | 44篇 |
2000年 | 32篇 |
1999年 | 26篇 |
1998年 | 25篇 |
1997年 | 13篇 |
1996年 | 19篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 21篇 |
1992年 | 25篇 |
1991年 | 22篇 |
1990年 | 16篇 |
1989年 | 26篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 17篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 10篇 |
1979年 | 15篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1974年 | 12篇 |
1973年 | 9篇 |
排序方式: 共有1668条查询结果,搜索用时 15 毫秒
101.
Osamu Takimura Hiroyuki Fuse Katsuzi Murakami Kazuo Kamimura Yukiho Yamaoka 《应用有机金属化学》1996,10(9):753-756
Uptake and reduction of arsenate [AS(V)] by Dunaliella sp. cells were determined to investigate the metabolic processes of arsenic in the alga. Cellular uptake of arsenic by Dunaliella sp. cells was markedly affected by the form of arsenic in the medium. The content of arsenic taken up by Dunaliella sp. cells increased rapidly with time on addition of As(V) to the medium. However, in the case of addition of arsenite [As(III)], the gradient of arsenic uptake by Dunaliella sp. cells was low, and arsenic content was small. In the water-soluble fraction of arsenic taken up by Dunaliella sp. cells with exposure to As(V), arsenic was in the forms of organic arsenic, As(V) and As(III). The content of As(V) in the water-soluble fraction increased with exposure time. The content of As(III) also increased with time, but remained constant after 5 h of exposure. On the other hand, organic arsenic content was small and did not increase with time. It was found that Dunaliella sp. takes up As(V) and readily reduces it to As(III) 相似文献
102.
Tairin Kawasaki Naoki Ishida Masahiro Murakami 《Angewandte Chemie (International ed. in English)》2020,59(41):18267-18271
A convenient method is reported to specifically acylate phenolic hydroxyl groups through a radical pathway. When a mixture of an aldehyde and a phenol in ethyl acetate is irradiated with blue light in the presence of iridium and nickel bromide catalysts at ambient temperature, phenoxyl and acyl radicals are transiently generated in situ and cross‐couple to furnish an ester. Aliphatic hydroxy groups remain untouched under the reaction conditions. 相似文献
103.
Fe K‐Edge X‐ray Absorption Fine Structure Determination of γ‐Al2O3‐Supported Iron‐Oxide Species
下载免费PDF全文
![点击此处可从《Chemphyschem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Atsuko Tomita Dr. Takeshi Miki Takeru Tango Tatsuro Murakami Hideyuki Nakagawa Dr. Yutaka Tai 《Chemphyschem》2015,16(9):2015-2020
The structure of FeOx species supported on γ‐Al2O3 was investigated by using Fe K‐edge X‐ray absorption fine structure (XAFS) and X‐ray diffraction (XRD) measurements. The samples were prepared through the impregnation of iron nitrate on Al2O3 and co‐gelation of aluminum and iron sulfates. The dependence of the XRD patterns on Fe loading revealed the formation of α‐Fe2O3 particles at an Fe loading of above 10 wt %, whereas the formation of iron‐oxide crystals was not observed at Fe loadings of less than 9.0 wt %. The Fe K‐edge XAFS was characterized by a clear pre‐edge peak, which indicated that the Fe?O coordination structure deviates from central symmetry and that the degree of Fe?O?Fe bond formation is significantly lower than that in bulk samples at low Fe loading (<9.0 wt %). Fe K‐edge extended XAFS oscillations of the samples with low Fe loadings were explained by assuming an isolated iron‐oxide monomer on the γ‐Al2O3 surface. 相似文献
104.
Risa Mutoh Hiroyuki Mino Reiko Murakami Tatsuya Uzumaki Masahiro Ishiura 《Applied magnetic resonance》2011,40(4):525-534
Site-directed spin labeling electron spin resonance (ESR) was applied to investigate the local environment of the cyanobacterial circadian clock protein KaiB. We prepared five cysteine residue-substituted mutants of KaiB labeled with maleimide spin label (MSL). By comparing the ESR spectra of KaiBs carrying MSL at different positions (Thr64, Lys67, Tyr94, Gly98, and Ala101), local conformational changes were identified. The ESR spectra of MSL-T64C and MSL-K67C showed the relatively slow motion of MSL characterized by τ?=?79 and 59?ns at 4°C, respectively. The spectra of MSL-Y94C, MSL-G98C and MSL-A101C showed relatively fast motion characterized by τ?=?8.0, 4.1 and 3.1?ns at 4°C, respectively. These differences were explained by the local environments of the position in KaiB. On incubation at 40°C for 24?h, all ESR spectra of the labeled KaiBs changed, which can be explained by the structural relaxation of KaiB. 相似文献
105.
106.
107.
Electronic states of P donors in Si nanocrystals (nc-Si) embedded in insulating glass matrices have been studied by electron spin resonance. Doping of P donors into nc-Si was demonstrated by the observation of optical absorption in the infrared region due to intraconduction band transitions. P hyperfine structure (hfs) was successfully observed at low temperatures. The observed splitting of the hfs was found to be much larger than that of the bulk Si:P and depended strongly on the size of nc-Si. The observed strong size dependence indicates that the enhancement of the hyperfine splitting is caused by the quantum confinement of P donors in nc-Si. 相似文献
108.
Novel ferromagnetism in Ca(1-x)La(x)B(6) is studied in terms of the Ginzburg-Landau theory for excitonic-order parameters, taking into account symmetry of the wave functions. We found that the minima of the free energy break both inversion and time-reversal symmetries, while the product of these two remains preserved. This explains various novelties of the ferromagnetism and predicts a number of magnetic properties, including the magnetoelectric effect, which can be tested experimentally. 相似文献
109.
Applying Kontsevich's iterated integral for tangles, we get an isotopy invariant of tangles. We give a method to compute the integral of a tangle combinatorially from modified integrals of some simple tangles. We localize the integral by moving the end points of the tangle to an extreme configuration, and modify the integral so that it is convergent. By using a similar technique, we generalize Kontsevich's invariant to a framed tangle. 相似文献
110.