全文获取类型
收费全文 | 2442篇 |
免费 | 541篇 |
国内免费 | 189篇 |
专业分类
化学 | 967篇 |
晶体学 | 23篇 |
力学 | 242篇 |
综合类 | 16篇 |
数学 | 314篇 |
物理学 | 1610篇 |
出版年
2023年 | 12篇 |
2022年 | 57篇 |
2021年 | 67篇 |
2020年 | 53篇 |
2019年 | 73篇 |
2018年 | 60篇 |
2017年 | 97篇 |
2016年 | 81篇 |
2015年 | 112篇 |
2014年 | 135篇 |
2013年 | 202篇 |
2012年 | 154篇 |
2011年 | 180篇 |
2010年 | 141篇 |
2009年 | 135篇 |
2008年 | 162篇 |
2007年 | 182篇 |
2006年 | 172篇 |
2005年 | 145篇 |
2004年 | 114篇 |
2003年 | 127篇 |
2002年 | 97篇 |
2001年 | 93篇 |
2000年 | 81篇 |
1999年 | 49篇 |
1998年 | 51篇 |
1997年 | 49篇 |
1996年 | 34篇 |
1995年 | 26篇 |
1994年 | 28篇 |
1993年 | 30篇 |
1992年 | 22篇 |
1991年 | 21篇 |
1990年 | 26篇 |
1989年 | 16篇 |
1988年 | 16篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 5篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1959年 | 1篇 |
排序方式: 共有3172条查询结果,搜索用时 15 毫秒
51.
A. G. Bubnov E. Yu. Burova V. I. Grinevich V. V. Rybkin J.-K. Kim H.-S. Choi 《Plasma Chemistry and Plasma Processing》2006,26(1):19-30
This study investigated the processes for the destruction of phenol and its derivatives (resorcin and pyrocatechol) in aqueous
solutions under the action of an oxygen dielectric barrier discharge (DBD) at atmospheric pressure in the presence or absence
of catalysts in the plasma zone. It was shown that the DBD had a high decomposition efficiency for phenol and its derivatives
(up to 99%). Phenol was the most stable and pyrocatechol was the least. In a plasma-catalytic hybrid process, the effective
rate constants for phenol, resorcin and pyrocatechol decomposition were 11, 4 and 2.5 times higher, respectively, than those
for the DBD treatment without catalysts. The process also resulted in a 1.4, 1.6 and 1.2 times higher rate of carboxylic acid
formation for phenol, resorcin and pyrocatechol, respectively. The fractional conversion into the respective carboxylic acids
reached 56% for phenol and 68% for resorcin and pyrocatechol. 相似文献
52.
Densities of N, H, and NH active species have been detected by laser-induced fluorescence (LIF) in N2-xH2 dc flowing discharges. A peak value of N atom densities far x = 0.2–0.5% and a plateau value of H atom densities between x = 1% and 90% in post-discharge conditions (0.05 sec, p = 2 torr) has been found. Comparison between LIF measurements of N atoms and the trend of the N2(B, v = II) population shows that the emission from this state can be used for monitoring N atoms. The NH radical has only been detected inside the discharge region.On leave from Instituto Tecnológico de Aeronáutica, CNPq, Brazil. 相似文献
53.
Blinov L. M. Golovkin A. G. Kaganov L. I. Oparin V. B. Razhavski A. A. Shterenberg A. M. Volodko V. V. Zyn V. I. 《Plasma Chemistry and Plasma Processing》1998,18(4):509-533
Time-resolved mass spectrometry was used for analysis of the plasma reactions in radio frequency (RF) SiCl
4
and SiCl
4
–O
2
discharges as functions of starting partial pressure and electrical power. Molecular concentrations of the reactants and products from SiCl
4
alone and with O
2
were obtained from the mass spectra and used for plotting the kinetic curves. The SiCl
4
and O
2
consumption rates were calculated from the kinetic curves and compared with results of theoretical simulation of the reaction. Direct electron impact decomposition was found to be the main pathway for pure SiCl
4
conversion. On the contrary, the consumption of SiCl
4
in the SiCl
4
+O
2
mixtures was largely chemical. The experimental macrokinetics are in agreement with a model in which oxidation is caused by the atomic oxygen. 相似文献
54.
DC cathodic polymerization of trimethylsilane (TMS) was carried out in plasma reactors with and without using anode assembly. In DC cathodic polymerization, the TMS plasma polymers are mainly deposited on the cathode (substrate) surface. As a result, fast deposition of TMS plasma polymers was easily achieved in DC cathodic polymerization as compared with AF or RF plasma polymerization. DC cathodic polymerization without using anode assembly has its advantageous features that the size and number of substrates (as cathodes) are not restricted by the size and the location of anode assembly. It was found that the maximum deposition rate on the cathode surfaces was obtained without anode assembly. The DC cathodic polymerization of TMS was conducted also in a large volume reactor with multiple cathodes (substrates). The same deposition mechanisms for DC cathodic polymerization with a single cathode also apply to the multiple cathodes. Uniform deposition on each cathode could be obtained with appropriate spacing of multiple cathodes and by adjusting the operational parameters, which are based on the current density and the system pressure. 相似文献
55.
M.?SunEmail author Y.?Wu J.?Li N.?H.?Wang J.?Wu K.?F.?Shang J.?L.?Zhang 《Plasma Chemistry and Plasma Processing》2005,25(1):31-40
OH radical in the corona discharge with pipe–nozzle–plate electrode has been diagnosed by optical emission spectroscopy. Spatial variations of OH radical emission in discharge gap have been measured. Relative intensity of OH radical emission spectroscopy increases with increasing water vapor flux injected into the reactor or intensity of electric field supported. In positive pulsed corona discharge, relative intensity is higher than that in positive DC corona discharge and lower than that in negative DC corona discharge. Strongest intensity of OH radical spectrum appears within the range of 5 mm near the discharge nozzle- electrode. In addition, it is proved that the efficiency of desulphurization from flue gas by pulsed corona discharge plasma processes can be improved when OH radical is produced in the reactor. 相似文献
56.
This paper describes the loss and recovery in the hydrophobicity of unfilled high temperature vulcanized silicone rubber (HTV-SR) resulting from corona discharge. In this study, HTV-SR specimens were exposed to corona stress generated by a parallel needle-plane electrode system, and physicochemical analyses on the surface layer of SR before and after corona discharge treatment were carried out by using Fourier transform infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is demonstrated that hydrophilic OH groups that are by-products of ageing can be formed instead of hydrophobic CH3 groups on the surface of aged SR and the corona discharge plays an important role on the temporary loss of hydrophobicity. After a substantial period of ‘rest’, the hydrophobic recovery of SR results from the diffusion of low-molecular weight (LMW) silicone fluid from the bulk onto the aged layer. 相似文献
57.
Sergey Y. Savinov Hwaung Lee Hyung Keun Song Byung-Ki Na 《Plasma Chemistry and Plasma Processing》2003,23(1):159-173
An experimental study of plasmachemical reaction involving CH4 and N2 molecules in rf discharge was studied in order to know the effect of vibrational excitation of N2 molecules. When the relative nitrogen concentration was greater than 0.8, the main product of CH4 decomposition was HCN, and the rate of methane decomposition at this condition was faster than that one in pure methane. These results could be confirmed through the mass spectroscopic method. The reason for these results is the vibrational energy of N2 excited by rf discharge. The chain reaction mechanisms of producing HCN by vibrational excitation of N2 were examined closely through numerical simulation. The rate-controlling step was the dissociation reaction of excited nitrogen molecule to the atomic nitrogen, so the process of HCN synthesis was limited by the value of reaction constant, kN. 相似文献
58.
F. Sigeneger Yu. B. Golubovskii I. A. Porokhova R. Winkler 《Plasma Chemistry and Plasma Processing》1998,18(2):153-180
The nonlocal behavior of the electrons in strongly modulated and period-averaged electric fields typical of s- and p-striations in neon glow discharge plasmas is investigated by numerically solving the axially inhomogeneous electron Boltzmann equation. A good agreement between the period lengths measured in the striations and those obtained from the spatially periodic electron relaxation in the period-averaged field of the striations is found confirming the close relation of both phenomena. The s- and p-striations represent the fundamental and first harmonics of the inherent periodic electron relaxation. Furthermore, starting from different boundary conditions the establishment of the velocity distribution function and of selected macroscopic quantities of the electrons into unique periodic states under the action of strongly modulated striation-like fields is investigated. It is shown that the same damping processes that cause in homogeneous fields a relaxation into homogeneous states lead to unique periodic states in strongly modulated fields. 相似文献
59.
60.
V.?I.?VigdorovichEmail author L.?E.?Tsygankova O.?V.?Alekhina T.?P.?D'yachkova 《Russian Journal of Electrochemistry》2005,41(10):1046-1052
The effect of thiourea (0.5–10 mM) on the kinetics of the hydrogen evolution reaction (HER) at iron and the hydrogen transport through a steel membrane out of ethylene glycol (containing 2 and 10 wt % H2O) and aqueous solutions containing HCl (0.1–0.99 M) with a constant ionic strength equal to unity is studied in parallel experiments. The presence of 0.5 mM of thiourea in the solutions raises the overvoltage of hydrogen evolution, while a subsequent increase in its concentration does not effect the HER kinetics. The dependence of the flux of hydrogen diffusion through the membrane on the thiourea content passes through a maximum. 相似文献