全文获取类型
收费全文 | 99篇 |
免费 | 4篇 |
学科分类
工业技术 | 103篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 7篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有103条查询结果,搜索用时 15 毫秒
1.
2.
The potential of a commercially available double-focusing magnetic sector ICP mass spectrometer (Element, Finnigan MAT, Bremen, Germany) for precise isotope ratio measurement at the low-resolution setting (R = 300) was evaluated. Optimization of scanning conditions led to a relative standard deviation for a set of 10 consecutive 2 min measurements of ~0.1% ((206)Pb(+)/(207)Pb(+)) at signal intensities of ~200?000 counts/s (peak height). This compares favorably with the best values ever reported for quadrupole ICPMS and barely exceeds the theoretical value (counting statistics). Increasing the signal intensity to values ≥500?000 counts/s (peak height) resulted in a further reduction of the RSDs obtained (for both (25)Mg(+)/(26)Mg(+) and (206)Pb(+)/(207)Pb(+)) to typically 0.04%. These figures are remarkably better than those reported for commercially available quadrupole ICPMS systems. This improvement significantly reduces the difference between isotope ratio precision of ICPMS on one hand and those of thermal ionization mass spectrometry and plasma source multiple collector mass spectrometry on the other. 相似文献
3.
Juan Carlos Gomez Erik Boiy Marie-Francine Moens 《Knowledge and Information Systems》2012,31(1):23-53
This paper reports on email classification and filtering, more specifically on spam versus ham and phishing versus spam classification,
based on content features. We test the validity of several novel statistical feature extraction methods. The methods rely
on dimensionality reduction in order to retain the most informative and discriminative features. We successfully test our
methods under two schemas. The first one is a classic classification scenario using a 10-fold cross-validation technique for
several corpora, including four ground truth standard corpora: Ling-Spam, SpamAssassin, PU1, and a subset of the TREC 2007
spam corpus, and one proprietary corpus. In the second schema, we test the anticipatory properties of our extracted features
and classification models with two proprietary datasets, formed by phishing and spam emails sorted by date, and with the public
TREC 2007 spam corpus. The contributions of our work are an exhaustive comparison of several feature selection and extraction
methods in the frame of email classification on different benchmarking corpora, and the evidence that especially the technique
of biased discriminant analysis offers better discriminative features for the classification, gives stable classification
results notwithstanding the amount of features chosen, and robustly retains their discriminative value over time and data
setups. These findings are especially useful in a commercial setting, where short profile rules are built based on a limited
number of features for filtering emails. 相似文献
4.
5.
Silvia Folloni Gianni Bellocchi Adelina Prospero Maddalena Querci William Moens Monica Ermolli Guy Van den Eede 《Food Analytical Methods》2010,3(4):304-312
Real-time PCR (RTi-PCR) is the technique of choice for event-specific quantification of genetically modified organisms (GMOs)
by determining the amount of event with respect to a species-specific reference gene. Reference genes can be amplified from
the genome extracted from Certified Reference Materials (CRMs) or from ad hoc designed plasmids. In the present study, we
statistically evaluate the performance of RTi-PCR protocols for GM maize MON810 event by using both genomic DNA from conventional
CRMs and a plasmid containing sequences representative of four maize species-specific reference genes. The significance of
simple and interaction effects of several variables included in the experimental design on DNA quantification methods and
RTi-PCR were evaluated and discussed. Statistically significant differences on Ct values may have an impact on the GMOs quantification
and consequently on the compliance of GM quantification-established legal thresholds. Our results confirm the reliability
of the plasmid as alternative calibrant for the calculation of GMOs copy number. 相似文献
6.
Steven Corthals Joris Van Nederkassel Jan Geboers Hendrik De Winne Jasper Van Noyen Bart Moens Bert Sels Pierre Jacobs 《Catalysis Today》2008,138(1-2):28
Dry reforming of methane was studied over Ni catalysts supported on γAl2O3, CeO2, ZrO2 and MgAl2O4 (670 °C, 1.5 bar, 16–20 l CH4 mlcatalyst−1 h−1). It is shown that MgAl2O4 supported Ni catalysts promoted with both CeO2 and ZrO2 are promising catalysts for dry reforming of methane with carbon dioxide. Within a certain composition range, the simultaneous promotion with CeO2 and ZrO2 has great influence on the amount of coke and the catalyst service time. XRD analyses indicate that formation of crystalline CexZr1−xO2 mixed oxide phases occurs on double promotion. In particular, incorporation of low amounts of Zr in the CeO2 fluorite structure provides stable dry reforming catalysis. As shown with TPR, promotion leads to a higher reduced state of Ni. SEM, XRD and TPR analyses demonstrate that highly dispersed, doubly promoted Ni catalysts with a strong metal-support interaction are essential for stable dry reforming and suppression of the formation of carbon filaments. 相似文献
7.
The problem of determining the provenance of the white marble used for antique artifacts has been tackled in different ways. During the past decade it became clear that a multimethod approach is required to solve the problem. In addition, reliable reference material, i.e., samples collected at the ancient quarry sites in an archaeologically and geologically justified manner, turned out to be a prerequisite for reliable provenance determination. A multimethod approach based on petrography, stable isotope analysis of O and C, and trace element analysis yields complementary information. These methods were applied to the same set of 225 quarry samples. When processed with powerful statistical methods, the data thus obtained allowed all major types of marble used in antiquity to be distinguished. Thus, most problems concerning the provenance of artifacts can be solved. This approach was successfully applied to the provenance determination of about 75 artifacts from different museums in Europe and the USA. 相似文献
8.
Anghel C. Bakeroot B. Chauhan Y.S. Gillon R. Maier C. Moens P. Doutreloigne J. Ionescu A.M. 《Electron Device Letters, IEEE》2006,27(7):602-604
This letter reports on the extraction of the threshold voltage of laterally diffused MOS transistors. A clear analysis of the device physics is performed, highlighting the correlation between the change of the electron charge distribution along the channel and the device capacitance variations when the gate voltage is swept. Using numerical simulations, it is shown that the peak of the gate-to-drain capacitance is related to the transition of the surface from weak to moderate inversion in the intrinsic MOS transistor at the location of the maximum doping concentration, which corresponds to the threshold voltage of the device according to the MOS theory. Comparison between conventional I/sub D///spl radic/g/sub m/ extraction and the new proposed capacitance peak method is performed on both technology computer-aided design simulations and measurements in order to confirm the new experimental technique and related theory. 相似文献
9.
Serge Leimanis Sandrine Hamels Florence Nazé Guillaume Mbongolo Mbella Myriam Sneyers Rupert Hochegger Hermann Broll Lillian Roth Klára Dallmann Adrienn Micsinai José Luis La Paz Maria Pla Claudia Brünen-Nieweler Nina Papazova Isabel Taverniers Norbert Hess Britta Kirschneit Yves Bertheau Colette Audeon Valérie Laval Ulrich Busch Sven Pecoraro Katrin Neumann Sibylle Rösel Jeroen van Dijk Esther Kok Gianni Bellocchi Nicoletta Foti Marco Mazzara William Moens José Remacle Guy Van Den Eede 《European Food Research and Technology》2008,227(6):1621-1632
A new screening method for the detection and identification of GMO, based on the use of multiplex PCR followed by microarray, has been developed and is presented. The technology is based on the identification of quite ubiquitous GMO genetic target elements first amplified by PCR, followed by direct hybridisation of the amplicons on a predefined microarray (DualChip® GMO, Eppendorf, Germany). The validation was performed within the framework of a European project (Co-Extra, contract no 007158) and in collaboration with 12 laboratories specialised in GMO detection. The present study reports the strategy and the results of an ISO complying validation of the method carried out through an inter-laboratory study. Sets of blind samples were provided consisting of DNA reference materials covering all the elements detectable by specific probes present on the array. The GMO concentrations varied from 1% down to 0.045%. In addition, a mixture of two GMO events (0.1% RRS diluted in 100% TOPAS19/2) was incorporated in the study to test the robustness of the assay in extreme conditions. Data were processed according to ISO 5725 standard. The method was evaluated with predefined performance criteria with respect to the EC CRL method acceptance criteria. The overall method performance met the acceptance criteria; in particular, the results showed that the method is suitable for the detection of the different target elements at 0.1% concentration of GMO with a 95% accuracy rate. This collaborative trial showed that the method can be considered as fit for the purpose of screening with respect to its intra- and inter-laboratory accuracy. The results demonstrated the validity of combining multiplex PCR with array detection as provided by the DualChip® GMO (Eppendorf, Germany) for the screening of GMO. The results showed that the technology is robust, practical and suitable as a screening tool. 相似文献
10.
Electrothermal vaporization from a graphite furnace was used in combination with inductively coupled plasma mass spectrometry (ICPMS) for the determination of Pt and Rh in environmental matrixes. Solid samples of tunnel dust, grass, and atmospheric aerosol collected on a cellulose filter could be analyzed directly, such that sample dissolution-which is not self-evident for the determination of platinum group metals-could be avoided. By heating the graphite furnace according to a multistep temperature program, spectral interferences were avoided, since a "dry" plasma was obtained, while "parent" ions such as Cu, Zn, and Pb, giving origin to interfering molecular ions, were vaporized during the thermal pretreatment step. For tunnel dust, the most demanding sample matrix, a mixture of HCl and HF was used as a modifier to stimulate the vaporization of matrix components during the thermal pretreatment step and, hence, to alleviate matrix-induced analyte signal suppression during the actual vaporization step. Calibration was accomplished by means of single standard addition with an aqueous standard solution. The results obtained agreed within the experimental uncertainty with the corresponding reference values (certified values or results obtained using pneumatic nebulization ICPMS), while relative standard deviations of < or = 15% were typical for both Pt and Rh. In all samples, a Pt/Rh ratio of approximately 6-8 was established. For a typical sample mass of 2 mg, limits of detection were 0.35 ng/g for Pt and 0.05 ng/g for Rh. 相似文献