全文获取类型
收费全文 | 199篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 51篇 |
金属工艺 | 6篇 |
机械仪表 | 1篇 |
建筑科学 | 12篇 |
能源动力 | 4篇 |
轻工业 | 25篇 |
水利工程 | 1篇 |
无线电 | 21篇 |
一般工业技术 | 19篇 |
冶金工业 | 17篇 |
原子能技术 | 7篇 |
自动化技术 | 35篇 |
出版年
2021年 | 2篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 17篇 |
2012年 | 8篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 19篇 |
2008年 | 4篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有203条查询结果,搜索用时 15 毫秒
91.
A new modification of electrical low pressure impactor (ELPI) for the particle effective density measurement is presented. The system is capable of real-time operation and it is based on the serial measurement of mobility and aerodynamic diameter. In the studied configuration, a zeroth order mobility analyser is installed inside of the ELPI-instrument. The system is feasible for single modal distributions. For several particle materials and varying size distributions, the measured average density values were within 15% of the values obtained with a reference method. 相似文献
92.
Parallel interference cancellation (PIC) based channel parameter estimators for frequency selective fading channels are proposed for the uplink in code-division multiple-access (CDMA) mobile communication systems. The performance of PIC based algorithms depends heavily on the quality of the multiple-access interference estimates, which can be improved by using adaptive channel estimation filters. The performance of two adaptive complex channel coefficient estimation filters has been verified in a fading channel by computer simulations. According to the results, the PIC based adaptive channel estimators outperform clearly conventional, successive interference cancellation, and decorrelation based adaptive channel estimators. The PIC method is also used in delay tracking. By using the principles of sample-correlate-choose-largest (SCCL) delay trackers, a robust algorithm for multiuser delay tracking in fading channels is obtained. 相似文献
93.
Alcohol has been reported to increase the urinary excretion of dolichols, and urinary dolichols are suggested to be derived from the lysosomes of the renal cells. In the present study we examined the effects of alcohol and glucagon on the biliary excretion of dolichols in rats. Chronic ethanol treatment decreased both biliary dolichol and beta-hexosaminidase excretion. The absolute amount of dolichol excreted into the bile correlated highly significantly with the absolute amount of biliary beta-hexosaminidase. Our results indicate that biliary dolichols are--at least in part--derived from hepatic lysosomes. Decreased biliary dolichol output during chronic alcohol administration suggests that urinary and biliary dolichol excretions are regulated independently of each other. 相似文献
94.
Jorma Hls Kari Koski Ralf-Johan Lamminmki Eija Silynoja Przemysaw Dere Wiesaw Strk 《Journal of Alloys and Compounds》1997,250(1-2):370-374
The formation of cation solid solution in the (La1−xGdx)OCl:Eu3+ (0≤xGd≤1; ΔxGd=0.1) series was studied by photoluminescence spectroscopy. The luminescence from the 5D0–2 to the 7F0–4 levels of the Eu3+ ion in the (La1−xGdx)OCl series was recorded at 77 K by using argon ion laser excitation (457.9 nm). The interpretation of the spectra according to the C4v site symmetry of the Eu3+ ion in the tetragonal PbFCl-type structure yielded nearly complete sets (18 to 19 levels) for the 7F0–4 levels. Simulations of the Stark level schemes were carried out with the aid of a phenomenological c.f. theory utilizing the five non-zero c.f. Bqk parameters (B02, B04, B44, B06 and B46) allowed for the C4v site symmetry. By using the calculated c.f. parameter sets a quantitative measure was obtained to monitor the formation of cation solid solutions. The strength of the c.f. effect was estimated with the c.f. strength parameters S and Sk (k=2, 4 and 6). The c.f. parameter sets reproduced the experimental 7FJ (J=0–4) energy level schemes with the rms deviations between 4 and 11 cm−1. The individual parameters as well as the c.f. strength parameters were found to evolve in a smooth manner indicating complete solid solubility in the (La1−xGdx)OCl series. Some local distortions from the C4v symmetry — probably of long range—leading to the splitting of the 7F1 doubly degenerate E level were observed, however. 相似文献
95.
96.
97.
The concentration quenching of trivalent terbium emissions from UV-excited (La, Tb) OBr and (Gd, Tb)2O2S phosphors was studied. The activation concentration x was varied from 5·10?5 to 0.2 for (La1?xTbx) OBr and from 10?3 to 0.1 for (Gd1?xTbx)2O2S. emissions (blue) were observed to quench first and the Tb3+ concentration giving rise to maximum intensity was 0.003 in (La, Tb) OBr and between 0.005 and 0.01 in (Gd, Tb)2O2S. The optimum concentration for (green) emissions was 0.05 in (La, Tb) OBr and 0.03 in (Gd, Tb)2O2S. Dipole-dipole and dipole-quadrupole interactions are possible mechanisms for the quenching of emissions from the 5D3 and 5D4 levels.A method for determining the Tb3+ concentration in these phosphors, based on the intensity ratios of the and transitions, is also presented. 相似文献
98.
ABSTRACTRevaporisation of the fission products deposited in the primary circuit of a reactor was identified as a possible late source of fission product release during a severe accident: e.g. loss of coolant accident (LOCA). Subsequent testing has shown that revaporisation is very likely to occur given a breach of the reactor and is an important contributor for the source term release to the containment and biosphere. The first part reviews the revaporisation mechanisms of Cs and other volatile or semi-volatile fission products transported in the primary circuit that were derived from the Phebus FP and associated programmes. The second part examines the separate effects testing to determine the high temperature chemistry of volatile and semi-volatile fission products (I, Mo, Ru) and structural materials (Ag, B), as well as atmospheric effects that substantially affect the source term. Finally, it examines Cs data from reactor accident sites that is providing additional knowledge of longer-term fission product chemistry. The results have been summarised in the form of a table and schematic diagram. This accumulated knowledge and experience has important applications in minimising contamination during decommissioning and site remediation techniques, as well as improving SA simulation codes and raising nuclear safety. 相似文献
99.
100.
Heterogeneous Euclidean-overlap metric and heterogeneous value difference metric given in machine learning literature are
useful for the consideration of mixed-type data for machine learning, pattern recognition and data mining tasks. Mixed-type
variables are quite common in practical problems, but this property has been taken into account only seldom in pattern recognition,
data mining and decision making algorithms. We observed that these two distance measures are not actually metrics after having
found a special situation when they are not metric, but pseudometric, a feature to be noted while using them. Nevertheless,
by changing their definitions somewhat, it is possible to meet the metricity. Especially in medical applications, the redefinition
of the two measures might be important, since otherwise it is possible in theory that, for example, two identical cases would
be classified differently. Nearest neighbor searching tests with medical data were run to illustrate the behavior of these
measures. Notwithstanding the violation of the metricity their original forms yielded slightly better classification results.
The reason was that in real data sets tested there were very few almost similar cases according to these distance measures,
and the original forms based on more separating distances than the redefinitions were slightly better in the classification. 相似文献