全文获取类型
收费全文 | 606篇 |
免费 | 30篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 155篇 |
金属工艺 | 5篇 |
机械仪表 | 18篇 |
建筑科学 | 10篇 |
能源动力 | 12篇 |
轻工业 | 95篇 |
水利工程 | 2篇 |
石油天然气 | 8篇 |
无线电 | 70篇 |
一般工业技术 | 72篇 |
冶金工业 | 66篇 |
原子能技术 | 2篇 |
自动化技术 | 109篇 |
出版年
2023年 | 9篇 |
2022年 | 44篇 |
2021年 | 34篇 |
2020年 | 15篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 18篇 |
2015年 | 23篇 |
2014年 | 24篇 |
2013年 | 46篇 |
2012年 | 41篇 |
2011年 | 28篇 |
2010年 | 27篇 |
2009年 | 26篇 |
2008年 | 12篇 |
2007年 | 34篇 |
2006年 | 21篇 |
2005年 | 15篇 |
2004年 | 16篇 |
2003年 | 18篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 13篇 |
1998年 | 22篇 |
1997年 | 20篇 |
1996年 | 16篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有636条查询结果,搜索用时 15 毫秒
31.
Maria Grazia Calabrese Gianfranco Mamone Simonetta Caira Pasquale Ferranti Francesco Addeo 《Food chemistry》2009
The unnatural amino acid lysinoalanine (LAL) has been identified in milk and cheese products by liquid chromatography mass spectrometry (LC/ESI/MS) with selective ion monitoring (SIM) of the 9-fluorenyl-methylchloro-formate (FMOC) derivative. LAL is not present in raw milk or derived from Mozzarella cheese; however, high amounts of LAL are found in calcium caseinate and milk powder. As expected, milk fortified with caseinate or whey protein powder produces cheese with higher LAL content. Our analytical procedure is based on the simultaneous detection of specific ion masses of the FMOC–LAL derivative and the N-ε-methyl-lysine internal standard. A linear relationship was observed within the 0.2–20 ppm concentration range, in addition to a high correlation coefficient and ∼3% relative standard deviation. 相似文献
32.
G. De Pasquale A. Somà A. Ballestra 《Analog Integrated Circuits and Signal Processing》2009,61(3):215-222
This work is focused on the reliability of gold microcantilevers under the effect of mechanical fatigue. A dedicated device
for testing the material is designed and built; the material degradation is monitored during the tests by means of a novel
technique based on the control of the pull-in voltage of the device, which was demonstrated to be related to the loss of mechanical
strength. The fatigue effect is produced through the excitation of the device at a frequency near the resonance; the excitation
frequency and the time of actuation are used as a counter for the number of cycles. The lifetime of the device is measured
under variable levels of vibration amplitudes; the number of cycles to failure is estimated within a specific range of actuation
voltages by means of the W?hler diagram obtained by experiments. The fatigue limit is also estimated following the stair-case method. 相似文献
33.
34.
Chianese L Caira S Lilla S Pizzolongo F Ferranti P Pugliano G Addeo F 《The Journal of dairy research》2004,71(1):14-19
A novel electrophoretic alpha-lactalbumin (alpha-la) variant was detected in the Italian water buffalo breed. The isoelectric point of the variant, labelled A, was lower than the most frequent variant B. It presented an allelic frequency of 0.5% compared with the 97.1% of the BB allele. From Liquid Chromatography-Electrospray Ionization/Mass spectrometry, the molecular mass of the two alpha-la A and B variants were measured as 14,235.1+/-0.8 and 14,236.1+/-0.9 Da, respectively. The two proteins were sequenced and differentiated from one another by a single amino acid substitution, Asn45(B)-->Asp45(A). As this amino acid substitution altered the N-glycosylation sequence consensus Asn45-X-Ser46 it may be deduced that the protein glycosylation level of the alpha-la A would decrease. 相似文献
35.
Easy access to large information collections is of great importance in many aspects of everyday life. However, limitations in information and communication technologies have so far prevented the average person from taking much advantage of existing resources. Historical documentaries held by national archives constitute some of the most precious yet least accessible cultural information. The ECHO project has facilitated accessibility to this type of precious information by developing a digital library (DL) service for historical films belonging to large national audiovisual archives. 相似文献
36.
Synthetic biology combines different branches of biology and engineering aimed at designing synthetic biological circuits able to replicate emergent properties useful for the biotechnology industry, human health and environment. The role of negative feedback in noise propagation for a basic enzymatic reaction scheme is investigated. Two feedback control schemes on enzyme expression are considered: one from the final product of the pathway activity, the other from the enzyme accumulation. Both schemes are designed to provide the same steady‐state average values of the involved players, in order to evaluate the feedback performances according to the same working mode. Computations are carried out numerically and analytically, the latter allowing to infer information on which model parameter setting leads to a more efficient noise attenuation, according to the chosen scheme. In addition to highlighting the role of the feedback in providing a substantial noise reduction, our investigation concludes that the effect of feedback is enhanced by increasing the promoter sensitivity for both schemes. A further interesting biological insight is that an increase in the promoter sensitivity provides more benefits to the feedback from the product with respect to the feedback from the enzyme, in terms of enlarging the parameter design space.Inspec keywords: biotechnology, enzymes, biological techniquesOther keywords: negative feedback impact, metabolic noise propagation, mathematical modelling, synthetic biological circuit, biotechnology industry, human health, environment, enzymatic reaction scheme, feedback control scheme, enzyme expression, enzyme accumulation, negative autoregulation, steady‐state average value, feedback performance, stochastic simulation algorithm, stochastic hybrid system modelling, noise attenuation, substantial noise reduction, feedback effect, parameter design space 相似文献
37.
Pasquale Russo Spena Manuela De Maddis Franco Lombardi Matteo Rossini 《Materials and Manufacturing Processes》2016,31(3):291-299
Dissimilar resistance spot welding of twinning induced plasticity (TWIP) and quenching and partitioning (Q&P) steel grades has been investigated by evaluating the effects of clamping force, welding current, and welding time on the microstructure, shear tension strength, and fracture of welded samples. The spot welding of TWIP and Q&P steels promotes the occurrence of an asymmetrical weld nugget with a greater dilution of TWIP steel because of its lower melting temperature and thermal conductivity. As a result, weld nuggets exhibit an austenitic microstructure. TWIP steel undergoes a grain coarsening in the HAZ, whereas Q&P steel undergoes some phase transformations. Welded samples tend to exhibit higher shear tension strength as they are joined at the highest welding current, even though an improper clamping force can promote excessive metal expulsion, thereby reducing the mechanical strength of the welded joints. Shear tension welded samples failed through interfacial fracture with partial thickness fracture mode for a low welding current, while partial thickness with button pull fractures were observed when a high welding current was used. The weld spots predominantly failed at the TWIP side. However, as TWIP steel can work harden significantly in the more resistant welded joints, the failures occur, instead, at the Q&P side. 相似文献
38.
Pasquale Lops Marco de Gemmis Giovanni Semeraro Cataldo Musto Fedelucio Narducci 《Journal of Intelligent Information Systems》2013,40(1):41-61
The rapid growth of the so-called Web 2.0 has changed the surfers’ behavior. A new democratic vision emerged, in which users can actively contribute to the evolution of the Web by producing new content or enriching the existing one with user generated metadata. In this context the use of tags, keywords freely chosen by users for describing and organizing resources, spread as a model for browsing and retrieving web contents. The success of that collaborative model is justified by two factors: firstly, information is organized in a way that closely reflects the users’ mental model; secondly, the absence of a controlled vocabulary reduces the users’ learning curve and allows the use of evolving vocabularies. Since tags are handled in a purely syntactical way, annotations provided by users generate a very sparse and noisy tag space that limits the effectiveness for complex tasks. Consequently, tag recommenders, with their ability of providing users with the most suitable tags for the resources to be annotated, recently emerged as a way of speeding up the process of tag convergence. The contribution of this work is a tag recommender system implementing both a collaborative and a content-based recommendation technique. The former exploits the user and community tagging behavior for producing recommendations, while the latter exploits some heuristics to extract tags directly from the textual content of resources. Results of experiments carried out on a dataset gathered from Bibsonomy show that hybrid recommendation strategies can outperform single ones and the way of combining them matters for obtaining more accurate results. 相似文献
39.
N. Baghdadi R. Pedreros N. Lenotre T. Dewez M. Paganini 《International journal of remote sensing》2013,34(17):3841-3849
Coastline mapping is of great interest in many different applications. In this Letter, we analyse the effect of the polarization and the incidence angle of the new Advanced Synthetic Aperture Radar (ASAR) sensor on coastline detection. Results indicate a marked dependence of the incidence angle and polarization on the delimitation between land and sea. At low incidence angles (<30°), delimitation is much clearer with HV polarization than with HH and VV polarizations. Delimitation is high whatever the polarization at high incidence angles (>30°). The multi‐polarization aspect of ASAR, in addition to its multi‐incidence aspect, therefore, allows coastline evolution to be monitored both more efficiently and more frequently. Consequently, the ASAR sensor is better adapted to coastline monitoring than the older ERS‐1/2 and Radarsat‐1 sensors. 相似文献
40.
D. Gastaldi F. Canonico S. Irico D. Pellerej M. C. Paganini 《Journal of Materials Science》2010,45(12):3169-3174
Near-infrared spectroscopy is a fast and easy-to-perform technique characterized by high sensitivity regarding water containing systems and for this reason it is a suitable tool for investigating structural modifications of hydrating cementing materials, even if the lack of knowledge in this field makes the interpretation of NIR vibrational bands very difficult. In this paper, the NIR spectrum of a hydrated ordinary Portland cement is extensively investigated and an interpretation of the different bands is proposed on the basis of both experimental evidence and reference to literature. The obtained results were applied to the investigation of cement hydration lasting up to 28 days, analyzing the variations detectable in the shape of the spectrum as the reaction went on. The degree of this variation, quantified through area calculations of the main significant bands, revealed a broad agreement with the degree of hydration of the paste measured by thermal methods. The findings of this research supply a solid foundation for future in-field application of NIR spectroscopy, for example, for investigations on cements with different hydration behavior, or to evaluate the effect of additives on cement pastes and, at a further level, for cement quality control. 相似文献