全文获取类型
收费全文 | 164篇 |
免费 | 5篇 |
专业分类
化学 | 82篇 |
力学 | 7篇 |
数学 | 17篇 |
物理学 | 63篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 6篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1974年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有169条查询结果,搜索用时 31 毫秒
121.
J.P. Albanese V. Alpe S. Aoki R. Arnold G. Baroni M. Barth J.H. Bartley D. Bertrand G. Bertrand-Coremans V. Bisi A.C. Breslin G. Carboni E. Chesi K. Chiba G.S. Cook M. Coupland G. Crosetti D.H. Davis Y. Yanagisawa 《Physics letters. [Part B]》1985,158(2):186-192
The associated production of a pair of beauty particles B? and by a 350 GeV π? interaction has been observed in an emulsion target inserted in an array of silicon microstrip detectors. Both beauty particles decay into charm particles, both of which are also observed to decay in the emulsion. Two negative muons were identified and their momenta measured in a large muon spectrometer. One muon has a pT of 1.9 GeV/c and is associated with a beauty particle decay. The other, with a pT of 0.45 GeV/c is associated with a charm particle decay. The flight times of the two beauty particles are respectively (0.8 ± 0.1) × 10?13 s and (5+2?1) × 10?13 s. Alternative interpretations of this event have negligible probability. 相似文献
122.
123.
Summary The depolarization, relative to the direction of a magnetic field, which accompanies the slowing-down of positrons in the
two enantiomers of camphor, down to the positronium formation energy, has been found to be greater (27%) in L-camphor. The
measuring method was based on the Ps relative yield, in the magnetic field, in triplet and singlet state. All other annihilation
features, as well as the intrinsic properties of Ps once formed, do not display significant differences between the two enantiomers.
This work was supported by INFM (Consorzio Nazionale di Fisica della Materia). 相似文献
124.
Summary The fate and properties of the ortho-Ps in aqueous solutions of CuSO4 and CuCl2 have been investigated through lifetime measurements and through a magnetic-quenching experiment. The obtained results are
interpreted in terms of exchange collisions between Ps and unpaired electron. An upper limit is given for the chemical-quenching
rate. Our measurements have shown that the presence of paramagnetic centres determines a strong shift of the levels of the
Ps hyperfine structure.
This work was entirely supported by CISM (Centro Interuniversitario di Struttura della Materia) of the Ministero della Publica
Istruzione and by GNSM (Gruppo Nazionale di Struttura della Materia) of CNR. 相似文献
125.
M. Bertolaccini A. Bisi G. Gambarini G. Padovini L. Zappa 《Applied Physics A: Materials Science & Processing》1977,12(1):93-96
The transient and steady effects of positronium yield in polyethylene, due to the application and removal of an external electric
field, have been studied. The time-dependent electric field effective in the Ps formation region was deduced from yield measurements. 相似文献
126.
In this work the effects of sludge disposal on pH values, buffer capacity and adsorption capacity of an acid soil were studied. A stabilized waste water sludge and a paper mill sludge were employed; the pH values of both sludges were higher than 8. The observed differences between soil-urban sludge and soil-paper mill sludge systems can be ascribed to the nature of the compounds present in the sludges and adsorbed on the soil. Both kinds of sludge are able to modify the natural pH of the soil, the buffer capacity and its capacity to retain metal. These modifications increase with increasing soil-sludge contact time and are higher for paper mill sludges. Temperature affects only the modifications due to urban sludge treatment. 相似文献
127.
128.
Stefano Banfi Enrico Caruso Loredana Buccafurni Raffaella Ravizza Marzia Gariboldi Elena Monti 《Journal of organometallic chemistry》2007,692(6):1269-1276
A panel of eight Zn-phthalocyanines (Zn-Pcs) (1)-(8), differently substituted on the benzo units, was synthesized either by direct cyclic-tetramerization of substituted phthalonitriles (compounds 1 and 2), or leading from the easily available tetrasulphonyl phthalocyanine to yield the sulfonamido derivatives 3 and 4, or else via the chloromethylation of precedent Zn-Pc followed by reaction with nucleophiles affording the dicationic Zn-Pcs (5) and (6) or the neutral Zn-Pcs (7) and (8). The phototoxicity of these new compounds was evaluated in vitro on human colon adenocarcinoma cell line (HCT116), and their effect compared with those induced by porfimer sodium. The results are reported as IC50 values, following exposure of the cells to different Zn-Pcs concentration and irradiation with a 500 W tungsten/halogen white lamp. The cationic Zn-Pc (5) and (6) together with the Zn-Pc (7), featuring 12 methoxy groups, were found good or fairly good photosensitizers while the more lipophilic Zn-Pcs (1)-(4) and (8) were found devoid of activity. 相似文献
129.
Marzia Mura Daniela Palmieri Davide Garella Antonella Di Stilo Patrizia Perego Giancarlo Cravotto 《Natural product research》2015,29(17):1657-1663
This study proposes an alternative technique to prevent heat degradation induced by classic procedures of bioactive compound extraction, comparing classical maceration/decoction in hot water of polyphenols from Mango (Mangifera indica L.) (MI) with ultrasound-assisted extraction (UAE) in a water solution of β-cyclodextrin (β-CD) at room temperature and testing their biological activity on TNFα-induced endothelial dysfunction. Both extracts counteracted TNFα effects on EAhy926 cells, down-modulating interleukin-6, interleukin-8, cyclooxygenase-2 and intracellular adhesion molecule-1, while increasing endothelial nitric oxide synthase levels. β-CD extract showed higher efficacy in improving endothelial function. These effects were abolished after pre-treatment with the oestrogen receptor inhibitor ICI1182,780. Moreover, the β-CD extract induced Akt activation and completely abolished the TNFα-induced p38MAPK phosphorylation. UAE and β-CD encapsulation provide an efficient extraction protocol that increases polyphenol bioavailability. Polyphenols from MI play a protective role on endothelial cells and may be further considered as oestrogen-like molecules with vascular protective properties. 相似文献
130.
Martina Rossi Concettina Cappadone Giovanna Picone Alessandra Bisi Giovanna Farruggia Federica Belluti Paolo Blasi Silvia Gobbi Emil Malucelli 《Molecules (Basel, Switzerland)》2022,27(12)
Osteosarcoma (OS) is a malignant disease characterized by poor prognosis due to a high incidence of metastasis and chemoresistance. Recently, Licochalcone A (Lic-A) has been reported as a promising agent against OS. Starting from chalcones selected from a wide in-house library, a new series was designed and synthetized. The antitumor activity of the compounds was tested on the MG63 OS cell line through the innovative Quantitative Phase Imaging technique and MTT assay. To further investigate the biological profile of active derivatives, cell cycle progression and apoptosis induction were evaluated. An earlier and more consistent arrest in the G2-M phase with respect to Lic-A was observed. Moreover, apoptosis was assessed by Annexin V staining as well as by the detection of typical morphological features of apoptotic cells. Among the selected compounds, 1e, 1q, and 1r proved to be the most promising antitumor molecules. This study pointed out that an integrated methodological approach may constitute a valuable platform for the rapid screening of large series of compounds. 相似文献