全文获取类型
收费全文 | 3245篇 |
免费 | 306篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 3554篇 |
出版年
2023年 | 53篇 |
2022年 | 42篇 |
2021年 | 117篇 |
2020年 | 110篇 |
2019年 | 112篇 |
2018年 | 193篇 |
2017年 | 192篇 |
2016年 | 216篇 |
2015年 | 153篇 |
2014年 | 188篇 |
2013年 | 389篇 |
2012年 | 206篇 |
2011年 | 215篇 |
2010年 | 196篇 |
2009年 | 168篇 |
2008年 | 110篇 |
2007年 | 77篇 |
2006年 | 45篇 |
2005年 | 23篇 |
2004年 | 32篇 |
2003年 | 33篇 |
2002年 | 31篇 |
2001年 | 30篇 |
2000年 | 28篇 |
1999年 | 23篇 |
1998年 | 19篇 |
1997年 | 19篇 |
1996年 | 25篇 |
1995年 | 20篇 |
1994年 | 28篇 |
1993年 | 24篇 |
1992年 | 23篇 |
1991年 | 18篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 16篇 |
1986年 | 15篇 |
1985年 | 26篇 |
1984年 | 30篇 |
1983年 | 25篇 |
1982年 | 24篇 |
1981年 | 23篇 |
1980年 | 19篇 |
1979年 | 17篇 |
1978年 | 13篇 |
1977年 | 19篇 |
1976年 | 18篇 |
1975年 | 18篇 |
1974年 | 17篇 |
1973年 | 18篇 |
排序方式: 共有3554条查询结果,搜索用时 312 毫秒
11.
Ivan Fortelný Monika Lapčíková František Lednický Zdeněk Starý Zdeněk Kruliš 《Polymer Engineering and Science》2008,48(3):564-571
This article is focused on the phase structure development in immiscible polymer blends during melt mixing. Nonuniformity of the phase structure, i.e., the coexistence of areas containing particles with markedly different size distribution, was detected in quenched and compression molded samples of a number of various blends prepared by long and intensive mixing in the chamber of a Plasticorder. The same effect was found also for polystyrene/polyamide blends prepared in a twin‐screw extruder. It was shown that neglecting nonuniformity of the phase structure can lead to considerable error in evaluation of the effect of system parameters on the blend morphology. The reasons for the effect were discussed and it was found that inhomogeneous flow field in mixers is a plausible explanation of the nonuniform phase structure. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献
12.
Mariana Ušáková Jozef Lukáč Rastislav Dosoudil Vladimír Jančárik Anna Grusková Elemír Ušák Jozef Sláma Jan Šubrt 《Journal of Materials Science: Materials in Electronics》2007,18(12):1183-1189
The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology.
The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed
by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and
possible applications of such materials. A strong correlation between the substituent content and resulting properties has
been observed, thus allowing preparation of material with the properties tailored for any particular application. 相似文献
13.
14.
V. Ocelík V. Z. Bengus E. B. Korolkova K. Csach J. Miškuf P. Duhaj 《Journal of Materials Science》1991,26(24):6699-6705
The fracture stress and the critical stress intensity factor of the Fe40Ni40B20 amorphous metallic ribbons 20 μm thick were measured in the temperature range 4.2–300 K and at deformation rates from 3.3×10−6 to 1.25×10−3 m−1 with the aim to obtain more information on the condition for the onset and development of the inhomogeneous plastic deformation
and fracture. 相似文献
15.
An efficient sampling scheme called Updated Latin Hypercube Sampling is presented. The proposed method is an improved variant of Latin Hypercube Sampling. It uses specially modified tables of independent random permutations of rank numbers which form the strategy of generating input samples for a simulation procedure. The method is presented in order to obtain these specially modified tables. The aim of this paper is to compare estimates of certain widely used statistical parameters obtained by Updated Latin Hypercube Sampling, Latin Hypercube Sampling and Simple Random Sampling. It is shown that Updated Latin Hypercube Sampling usually results in a substantial decrease of the variance in the estimates of commonly used statistical parameters and that the bias is quite small for a moderate number of simulations. This sampling technique seems to be generally very useful, efficient and superior to other methods especially in the case of statistical, sensitivity and probability analyses of complex analytical models with random input variables. 相似文献
16.
The current density used in electrochemical machining can be increased only up to a certain value, above which the formation of electric sparks on the cathode (tool) is observed, whereby the latter is damaged and the anode surface becomes rough. The present work is devoted to the measurement of this critical density for small metal cathodes placed on the wall of a flow-through channel for Reynolds numbers from 1265 up to 5902 and static pressures ranging from 0.1 up to 1.0 MPa. The results are correlated by criterion equations which gave values of critical (sparking) cathodic current density,j
s, with an average error of 7.1 % for laminar flow and 4.1 % for turbulent flow. The equations can be used for the calculation of the sparking current density for industrial flow-through cells for electrochemical machining. 相似文献
17.
P. Podhájecký B. Klápště P. Novák J. Mrha R. Moshtev V. Manev A. Nassalevska 《Journal of power sources》1985,14(4):269-275
A dozen CuO samples prepared under various conditions and from different starting materials were evaluated as cathode materials for a primary Li/CuO cell. The “thin electrode” method was used for rapid evaluation of the samples. Both coulombic efficiency and discharge voltage depend considerably on the method of synthesis. No correlation was found between the specific surface area and the resistivity of the samples on the one hand and the cathode performance on the other. Best results were obtained from CuO prepared by the oxidation of Cu2O under controlled temperature and time of oxidation. 相似文献
18.
19.
Summary the simulation described in Part I was applied to random step polyaddition of a trifunctional monomer and the results were compared with exact solution for an infinite system. The gel point conversions, the weight-average degree of polymerization before (P
w) and beyond (P
w,sol) the gel point, the sol fraction and the cycle rank were used for comparison. The best way for detection of the gel point conversion is the extrapolation of the gel fraction, w
g, to w
g=0. The largest fluctuations are exhibited by P
w and P
w,sol. To get results closer to the exact ones, one can repeat several experiments with smaller number of units or increase the number of units, the former way being somewhat more economical. Typical orders of magnitude used were 107 monomeric units. 相似文献
20.
The inhibiting action of N-arylpyrroles on aluminium in 0.17 mol dm–3 hydrochloric acid solution, in the temperature range 20–60 °C, was studied using potentiodynamic and electrochemical impedence spectroscopy techniques. The inhibiting efficiency of both investigated compounds 1-(2-fluorophenyl)-2,5-dimethylpyrrole (compound A) and 1-(2-fluorophenyl)-2,5-dimethylpyrrole-3-carbaldehyde (compound B) slightly increases with increasing temperature of the corrosive solution. Inhibitor adsorption on the elecrode surface decreases the apparent activation energy of the hydrogen evolution reaction. Compound A follows the Temkin adsorption isotherm, while its carbaldehyde derivative follows the Langmuir isotherm. The results of the apparent energy of activation and the standard free energy of adsorption point to stronger chemisorption of the compound A. However, due to additional condensation of molecules with carbaldehyde groups on the electrode surface, the carbaldehyde derivative exhibits even better inhibiting efficiency than compound A. The kinetic corrosion parameters, analysed in terms of the impedance data, show a satisfactory agreement with those obtained by the potentiodynamic method. 相似文献