全文获取类型
收费全文 | 590篇 |
免费 | 23篇 |
国内免费 | 7篇 |
专业分类
化学 | 509篇 |
晶体学 | 9篇 |
力学 | 1篇 |
数学 | 28篇 |
物理学 | 73篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 12篇 |
2015年 | 16篇 |
2014年 | 12篇 |
2013年 | 29篇 |
2012年 | 16篇 |
2011年 | 32篇 |
2010年 | 13篇 |
2009年 | 14篇 |
2008年 | 36篇 |
2007年 | 37篇 |
2006年 | 50篇 |
2005年 | 36篇 |
2004年 | 44篇 |
2003年 | 30篇 |
2002年 | 38篇 |
2001年 | 13篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 13篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1980年 | 11篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 6篇 |
1971年 | 2篇 |
排序方式: 共有620条查询结果,搜索用时 0 毫秒
81.
A redox species was extracted from water (50 x 10(-6) dm3) into a single micro-oil-droplet (30 x 10(-12) dm3) in contact with a microelectrode using microcapillary injection and manipulation techniques. Further, an in situ microanalysis of the solute in a single oil droplet was demonstrated by differential pulse voltammetry. The redox species of 10(-16) mol concentrated in the droplet could be quantitatively analyzed independently of the distribution coefficient of the solute between the oil and water phases. The potential of this technique was considered in terms of the preconcentration and separation as well as a microanalysis and an ultratrace analysis. 相似文献
82.
83.
Satoshi Fukui Osami Tsukamoto Kazuaki Negishi 《Physica C: Superconductivity and its Applications》1998,310(1-4):142-146
We investigated the AC loss characteristics of a low temperature NbTi AC wire by measuring the AC transport current losses in the external AC magnetic field whose components are the longitudinal and transverse ones. The measurement results showed that the AC losses were significantly dependent on the directions and magnitudes of the external longitudinal field component. The AC losses caused by the longitudinal and azimuthal field components were estimated by our previously derived model. The theoretical results well explained the dependence of the AC losses on the longitudinal field components. It was also shown that the AC losses can be substantially reduced by the proper choice of the twisting way. 相似文献
84.
Akira Takizawa Takao Negishi Kinzo Ishikawa 《Journal of polymer science. Part A, Polymer chemistry》1968,6(3):475-484
The influence of crystallinity on water sorption behavior by poly(vinyl alcohol) (PVA) was studied by using a PVA of low crystallinity (15% crystalline by x-ray analysis) and an annealed sample there from (46%) crystalline. With the increase of crystallinity, the sigmoid shape (which is a characteristic for the sorption isotherm of the low crystalline polymer) diminishes. The B.E.T. plots of the isotherms are linear between the relative vapor pressures of 0.1 and 0.4 as usual, and deviate from straight lines in the higher pressure range in the direction of a larger sorbed quantity than that predicted by the B.E.T. theory. This tendency is regarded as a kind of dissolution, and the Flory-Huggins interaction parameter χ1 was calculated. In both polymers, the χ1 versus pressure relation has a maximum, while overall χ1 values are smaller in the polymer of low crystallinity. The maximum point (which lies in the higher pressure region in case of the less crystalline sample) is considered to be a transition point from a phenomenon controlled mainly by an adsorption mechanism to a phenomenon controlled mainly by a dissolution mechanism. Accordingly, the separation of the isotherm into adsorption and a dissolution components was made, and the polymer fraction which contributes to the dissolution mechanism versus pressure relation was calculated. The result indicates that the crystalline region observed by x-ray analysis may partly contribute to the dissolution process at room temperature. 相似文献
85.
Allylalanes or benzylalanes react with either terminal or internal alkynes in the presence of a catalytic amount of Cl2ZrCp2 to produce in high yields cis-carboalumination products. 相似文献
86.
The signal quality of a fiber-optic distributed temperature sensor based on optical time domain reflectometry (OTDR) is improved using a pre-filtering technique in the iterative deconvolution method. Investigation of the performance is proposed using iteration conditions in which recovery rate of the signal-component is equal to that of the unfiltering technique. The recovered signal in the pre-filtering technique gives a good signal-to-noise ratio (SNR), 3 times of the unfiltered signal. Consequently, improvements in the OTDR signal with SNR of from 10 to 100 are obtained under the iterations for both distance and temperature resolutions. 相似文献
87.
88.
Measurement of high frequency ultrasound in liquids using high-resolution Bragg reflection technique
A new light scattering technique has been established for simultaneous measurement of ultrasonic velocity and absorption in liquids over a frequency range from 100 to 1000 MHz. The technique is applied to studies of vibrational relaxation in the uhf range, and the velocity-dispersion and absorption curves in several organic liquids are presented. 相似文献
89.
90.
Mohammad Mizanur Rahman Kazuaki Ninomiya Chiaki Ogino Nobuaki Shimizu 《Ultrasonics sonochemistry》2010,17(4):738-743
A non-woven titanium dioxide (TiO2) fabric was applied to disinfection by ultrasound (US) irradiation, and the disinfection efficiency and lipid peroxidation of Escherichia coli (E. coli) cell membrane were evaluated to investigate the killing process. The addition of non-woven TiO2 fabric enhanced hydroxyl (OH) radical generation and disinfection efficiency. Judging from the disinfection experiments using glutathione or t-butanol as a radical scavenger, the OH radical played a major role in cell killing in sonodynamic disinfection with non-woven TiO2 fabric. Moreover, to understand the detailed killing process, damage to cell membrane was also evaluated using a diphenyl-1-pyrenylphosphine (DPPP) fluorescent probe, which detects the membrane’s lipid peroxidation. The addition of non-woven TiO2 fabric aggravated this peroxidation. This aggravation was caused by the OH radical according to an assay using a radical scavenger. From these results, it was concluded that non-woven TiO2 fabric as a sonocatalyst promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced a major disorder in the E. coli cell membrane under US irradiation. 相似文献