全文获取类型
收费全文 | 223篇 |
免费 | 11篇 |
国内免费 | 5篇 |
专业分类
化学 | 204篇 |
晶体学 | 3篇 |
力学 | 4篇 |
数学 | 4篇 |
物理学 | 24篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 10篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 17篇 |
2011年 | 16篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 16篇 |
2007年 | 12篇 |
2006年 | 15篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1939年 | 1篇 |
排序方式: 共有239条查询结果,搜索用时 15 毫秒
51.
M Tada S Zhang S Malwadkar N Ishiguro J Soga Y Nagai K Tezuka H Imoto S Otsuka-Yao-Matsuo S Ohkoshi Y Iwasawa 《Angewandte Chemie (International ed. in English)》2012,51(37):9361-9365
Breaking news: A unique discontinuous property and an active phase of Ni/ordered Ce(2) Zr(2) O(x) (x=7-8) solid-solution catalysts were observed during methane steam reforming. The catalytic performance of Ni/Ce(2) Zr(2) O(x) strongly depended on the phase and oxygen content of the Ce(2) Zr(2) O(x) support. 相似文献
52.
E Pardo C Train H Liu LM Chamoreau B Dkhil K Boubekeur F Lloret K Nakatani H Tokoro S Ohkoshi M Verdaguer 《Angewandte Chemie (International ed. in English)》2012,51(33):8356-8360
Multiferroic materials: A novel class of multiferroics based on organic-inorganic hybrid materials is synthesized. The ferromagnetic properties originate from the coordination network, whereas the ferroelectricity results from the polar organic ions (see picture, M=magnetization and P=polarization). 相似文献
53.
Yoshimi Ohmae Natsuko I. Kobayashi Keitaro Tanoi Atsushi Hirose Takayuki Saito Akihiko Noda Naoko Iwata Akimasa Nakano Satoru Nakamura Tomoko M. Nakanishi 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):241-244
The mineral composition of frozen food of taro [Colocasia esculenta (L.) Schott] was analyzed to categorize the geographical production place of taro. The concentrations of Co and H2PO4
− were found to be useful to separate the producing place between Japan and China. The analysis was performed by instrumental
neutron activation analysis (INAA) and ion chromatography (IC). In the case of INAA, the samples were dried and sealed in
a vinyl bag and irradiated with thermal neutrons from JRR3M, installed at Japan Atomic Energy Agency (JAEA). The activated
samples were cooled down for a few weeks and the elements (Co, Cr, Fe, Rb, Zn) were determined. Cobalt concentration of frozen
taro from China was higher than that from Japan. The tendency was the same in the fresh sample of taro. When concentration
of H2PO4
− of frozen sample was measured, taro from Japanese product was higher than that of Chinese one, contrary to fresh sample.
This result might be caused by the leakage of H2PO4
− during freezing process, indicating that we should be careful to apply the discrimination indicators. In addition to Co,
there was a significant difference of Rb and Fe concentrations between frozen taro from Japan and China. 相似文献
54.
Lemos Judith L. S. Fontes Maria C. de A. Pereira Nei 《Applied biochemistry and biotechnology》2001,91(1-9):681-689
The use of purified xylan as a substrate for bioconversion into xylanases increases the cost of enzyme production. Consequently,
there have been attempts to develop a bioprocess to produce such enzymes using different lignocellulosic residues. Filamentous
fungi have been widely used to produce hydrolytic enzymes for industrial applications, including xylanases, whose levels in
fungi are generally much higher than those in yeast and bacteria. Considering the industrial importance of xylanases, the
present study evaluated the use of milled sugarcane bagasse, without any pretreatment, as a carbon source. Also, the effect
of different nitrogen sources and the C∶N ratio on xylanase production by Aspergillus awamori were investigated, in experiments carried out in solid-state fermentation. High extracellular xylanolytic activity was observed
on cultivation of A. awamori on milled sugarcane bagasse and organic nitrogen sources (45 IU/mL for endoxylanase and 3.5 IU/mL for β-xylosidase). Endoxylanase
and β-xylosidase activities were higher when sodium nitrate was used as the nitrogen source, when compared with peptone, urea,
and ammonium sulfate at the optimized C∶N ratio of 10∶1. The use of yeast extract as a supplement to the these nitrogen sources
resulted in considerable improvementin the production of xylanases, showing the importance of this organic nitrogen source
on A. awamori metabolism. 相似文献
55.
56.
Hashime Kanazawa Sadao Nishigaki Keitaro Senga 《Journal of heterocyclic chemistry》1984,21(4):969-974
Reactions of 6-arylidenehydrazino-1,3-dimethyluracil derivatives with N-bromosuccinimide leading to pyrazolo[3,4-d]pyrimidines, pyrimido[5,4-e]-as-triazines, and pyrimido[4,5-c]pyridazines are described. 相似文献
57.
A Reversible Fluorescent Probe for Real‐Time Live‐Cell Imaging and Quantification of Endogenous Hydropolysulfides
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Keitaro Umezawa Dr. Mako Kamiya Prof. Dr. Yasuteru Urano 《Angewandte Chemie (International ed. in English)》2018,57(30):9346-9350
The chemical biology of reactive sulfur species, including hydropolysulfides, has been a subject undergoing intense study in recent years, but further understanding of their “intact” function in living cells has been limited owing to a lack of appropriate analytical tools. In order to overcome this limitation, we developed a new type of fluorescent probe that reversibly and selectively reacts to hydropolysulfides. The probe enables live‐cell visualization and quantification of endogenous hydropolysulfides without interference from intrinsic thiol species such as glutathione. Additionally, real‐time reversible monitoring of oxidative‐stress‐induced fluctuation of intrinsic hydropolysulfides has been achieved with a temporal resolution on the order of seconds, a result which has not yet been realized using conventional methods. These results reveal the probe's versatility as a new fluorescence imaging tool to understand the function of intracellular hydropolysulfides. 相似文献
58.
Maria Antonieta Ferrara Josiane M. V. Mattoso Elba P. S. Bon Nei Pereira Jr. 《Applied biochemistry and biotechnology》2004,113(1-3):299-305
Although the quality of nitrogen source affects fermentation product formation, it has been managed empirically, to a large
extent, in industrial scale. Laboratory-scale experiments successfully use the high-cost proline as a nonrepressive source.
We evaluated urea as a substitute for proline in Saccharomyces cerevisiae ure2dal80 fermentations for asparaginase II production as a model system for nitrogen-regulated external enzymes. Maximum asparaginase
II levels of 265 IU/L were observed in early stationary-phase cells grown on either proline or urea, whereas in ammonium cells,
the maximum enzyme level was 157 IU/L. In all cases, enzyme stability was higher in buffered cultures with an initial pH of
6.5. 相似文献
59.
Photochemistry of γ,δ-Methano-α-enones Direct excitation (λ = 254 or ≥ 347 nm) converts the γ,δ-methano-α-enone (E)- 10 into the isomeric ether 23 and the isomeric diene-ketone 24 . Furthermore, on 1π,π*-excitation (λ = 254 nm) (E)- 10 undergoes an 1,3-homosigmatropic rearrangement yielding the enone (E)- 25 . In addition (E → Z)-isomerization of (E)- 10 and conversion of 10 to the isomeric furan 28 is observed. The isomerization (E)- 10 → 23 , 24 and (E)- 25 proceeds by photocleavage of the C(γ), C(δ)-bond, whereas the formation of 28 occurs by photocleavage the C(γ), C(δ)-bond together with that of the C(γ), C(δ′)-bond of 10 . On direct excitation the bicyclic diene-ether 23 yields the methano-enone 10 , the dieneketone 24 and the tricyclic ether 29 . Evidence is given, that the conversion 23 → 10 is a singulet process. On the other hand, the isomerization 23 → 24 and the intramolecular [2 + 2]-photocycloaddition 23 → 29 are shown to be triplet reactions. Irradiation (λ = 254 nm) of the homoconjugated ketone 24 yields the isomeric ketone 27 by an 1,3-acyl shift. The excitation of the (E)-enone 25 induces (E → Z)-isomerization and photoenolization to give the homoconjugated ketone 26 . 相似文献
60.
Kazuya Ogawa Tieqiao Zhang Keitaro Yoshihara Yoshiaki Kobuke 《Journal of the American Chemical Society》2002,124(1):22-23
Third-order nonlinear optical properties of two series of self-assembled porphyrin wires, one being terminated by zinc porphyrin and the other by free base porphyrin, were measured by femtosecond time-resolved optical Kerr effect. The hyperpolarizability values of the latter series were extremely large ranging from 10-30 to 10-29 esu, 10 times larger than the former. The behavior is accounted for by the contribution of terminal free base porphyrin to enhance the molecular polarization by acceptor nature toward central metalloporphyrin array. 相似文献