全文获取类型
收费全文 | 131篇 |
免费 | 1篇 |
专业分类
化学 | 55篇 |
力学 | 16篇 |
数学 | 32篇 |
物理学 | 29篇 |
出版年
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 6篇 |
2011年 | 10篇 |
2010年 | 5篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 3篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1963年 | 1篇 |
1928年 | 1篇 |
1897年 | 2篇 |
1889年 | 2篇 |
1887年 | 3篇 |
1881年 | 1篇 |
排序方式: 共有132条查询结果,搜索用时 15 毫秒
91.
Willard M Freeman Melinda E Lull Kruti M Patel Robert M Brucklacher Drake Morgan David CS Roberts Kent E Vrana 《BMC neuroscience》2010,11(1):29
Background
Many studies of cocaine-responsive gene expression have focused on changes occurring during cocaine exposure, but few studies have examined the persistence of these changes with cocaine abstinence. Persistent changes in gene expression, as well as alterations induced during abstinence may underlie long-lasting drug craving and relapse liability. 相似文献92.
We report the synthesis of a nearly single-cycle (3.7?fs), ultrafast optical pulse train at 78?MHz from the coherent combination of a passively mode-locked Ti:sapphire laser (6?fs pulses) and a fiber supercontinuum (1-1.4?μm, with 8?fs pulses). The coherent combination is achieved via orthogonal, attosecond-precision synchronization of both pulse envelope timing and carrier envelope phase using balanced optical cross-correlation and balanced homodyne detection, respectively. The resulting pulse envelope, which is only 1.1 optical cycles in duration, is retrieved with two-dimensional spectral shearing interferometry (2DSI). To our knowledge, this work represents the first stable synthesis of few-cycle pulses from independent laser sources. 相似文献
93.
A novel amperometric sensor system is presented which directly reflects the metabolic activity of prokaryotic and eukaryotic cells during cultivation. The principle of an externally mounted sensor is current measurement using a three-electrode system. Only living cells are detected since the current signal is based on a redox mediator. Added to a culture sample in its oxidized form, the mediator is reduced by cellular metabolism and subsequently re-oxidized at the anode. The spontaneous immobilisation of the cells in the reaction vessel of the sensor by swelling dextrane polymers (Sephadex) prior to measurement is the key to a fast, consistent signal. Even metabolically less active mammalian cells produce a reliable signal within a few minutes; this may open up future applications of the electrochemical sensor in closed loop process control not only for bacterial and fungal bioprocesses, but also in cell culture technology. 相似文献
94.
This paper presents a critical review of piezomodulation spectroscopy (that is, optical experiments which involve an ac stress) with the intent of examining its potential for future use. A brief account of the theory of strain effects in the linear response region, including important symmetry considerations, is presented, and several examples are given to illustrate these points. The advantages and shortcomings of the various types of ac stress apparatus are discussed as a guide to prospective experimenters. The unique feature of piezomodulation spectroscopy is that it can be used for studies in which the strain induces a linear response in the dielectric function. The author feels that this linear response region is the most promising area for future piezomodulation studies. 相似文献
95.
96.
The photoelectron angular distributions of furan, thiophene, and pyrrole are reported. The trends in the value of the asymmetry parameter β and in the shapes and positions of bands in the spectra are used to assign the peaks that correspond to ionization from the π orbitals in these molecules. 相似文献
97.
U. Sell 《Fresenius' Journal of Analytical Chemistry》1984,318(3-4):287-288
98.
99.
100.
W. Meisel CS. Vértes M. Lakatos-Varsányi 《Journal of Radioanalytical and Nuclear Chemistry》1995,190(2):289-298
Integral electron Mössbauer spectroscopy (ICEMS) and additionally some electrochemical methods were used to characterize the passivation process of iron (low carbon steel) in sulfate, sulfate+sulfite (a possible model solution of acid rain) solutions and in phospate buffer. The phase compositions and thicknesses of the passive layers formed due to the electrochemical polarizations were analyzed in dependence on the duration of the anodic passivations and on the pH of the used electrolytes. The passive layer, as determined from the Mössbauer spectra, consists mainly of -FeOOH, however in sulfite containing sulfate aqueous solution at pH 3.5 Fe3C and despite ex-situ circumstances FeSO4·H2O was detected after the shortest polarization time. The film thickness, which was found to grow nearly linearly with polarization time in pure sulfate solution and in phospate buffer, reached a maximum of 60–160 nm (depending on pH) in sulfate+sulfite solution after a passivation time of about 4 hours. It has been proved, that HSO3
–-ion, which is contained by acid rain, initiate pit formation under acid conditions and so enforces the corrosion of iron. The experimental results furthermore suggest, that not the whole oxidic layer is responsible for the passivity but only a very thin intermediate layer formed between an inner oxide layer of a cubic structure and the rhombic oxide (-FeOOH) cover. 相似文献