全文获取类型
收费全文 | 3242篇 |
免费 | 92篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 53篇 |
综合类 | 2篇 |
化学工业 | 604篇 |
金属工艺 | 73篇 |
机械仪表 | 49篇 |
建筑科学 | 114篇 |
矿业工程 | 21篇 |
能源动力 | 73篇 |
轻工业 | 279篇 |
水利工程 | 23篇 |
石油天然气 | 2篇 |
无线电 | 381篇 |
一般工业技术 | 498篇 |
冶金工业 | 839篇 |
原子能技术 | 57篇 |
自动化技术 | 268篇 |
出版年
2023年 | 23篇 |
2022年 | 27篇 |
2021年 | 40篇 |
2020年 | 27篇 |
2019年 | 39篇 |
2018年 | 40篇 |
2017年 | 41篇 |
2016年 | 54篇 |
2015年 | 58篇 |
2014年 | 54篇 |
2013年 | 115篇 |
2012年 | 90篇 |
2011年 | 138篇 |
2010年 | 82篇 |
2009年 | 107篇 |
2008年 | 123篇 |
2007年 | 79篇 |
2006年 | 85篇 |
2005年 | 65篇 |
2004年 | 63篇 |
2003年 | 75篇 |
2002年 | 81篇 |
2001年 | 69篇 |
2000年 | 64篇 |
1999年 | 75篇 |
1998年 | 266篇 |
1997年 | 181篇 |
1996年 | 119篇 |
1995年 | 94篇 |
1994年 | 88篇 |
1993年 | 86篇 |
1992年 | 52篇 |
1991年 | 73篇 |
1990年 | 46篇 |
1989年 | 46篇 |
1988年 | 45篇 |
1987年 | 37篇 |
1986年 | 27篇 |
1985年 | 46篇 |
1984年 | 40篇 |
1983年 | 31篇 |
1982年 | 20篇 |
1981年 | 23篇 |
1980年 | 24篇 |
1979年 | 19篇 |
1977年 | 28篇 |
1976年 | 56篇 |
1975年 | 19篇 |
1972年 | 18篇 |
1971年 | 17篇 |
排序方式: 共有3336条查询结果,搜索用时 15 毫秒
101.
Dynamic data mining has gained increasing attention in the last decade. It addresses changing data structures which can be observed in many real-life applications, e.g. buying behavior of customers. As opposed to classical, i.e. static data mining where the challenge is to discover pattern inherent in given data sets, in dynamic data mining the challenge is to understand – and in some cases even predict – how such pattern will change over time. Since changes in general lead to uncertainty, the appropriate approaches for uncertainty modeling are needed in order to capture, model, and predict the respective phenomena considered in dynamic environments. As a consequence, the combination of dynamic data mining and soft computing is a very promising research area. The proposed algorithm consists of a dynamic clustering cycle when the data set will be refreshed from time to time. Within this cycle criteria check if the newly arrived data have structurally changed in comparison to the data already analyzed. If yes, appropriate actions are triggered, in particular an update of the initial settings of the cluster algorithm. As we will show, rough clustering offers strong tools to detect such changing data structures. To evaluate the proposed dynamic rough clustering algorithm it has been applied to synthetic as well as to real-world data sets where it provides new insights regarding the underlying dynamic phenomena. 相似文献
102.
Francesco Giorgianni Diwa Koirala Karl T. Weber Sarka Beranova-Giorgianni 《International journal of molecular sciences》2014,15(6):9285-9301
Mitochondria are complex organelles that play critical roles in diverse aspects of cellular function. Heart disease and a number of other pathologies are associated with perturbations in the molecular machinery of the mitochondria. Therefore, comprehensive, unbiased examination of the mitochondrial proteome represents a powerful approach toward system-level insights into disease mechanisms. A crucial aspect in proteomics studies is design of bioanalytical strategies that maximize coverage of the complex repertoire of mitochondrial proteins. In this study, we evaluated the performance of gel-based and gel-free multidimensional platforms for profiling of the proteome in subsarcolemmal mitochondria harvested from rat heart. We compared three different multidimensional proteome fractionation platforms: polymeric reversed-phase liquid chromatography at high pH (PLRP), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and isoelectric focusing (IEF) separations combined with liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS), and bioinformatics for protein identification. Across all three platforms, a total of 1043 proteins were identified. Among the three bioanalytical strategies, SDS-PAGE followed by LC-MS/MS provided the best coverage of the mitochondrial proteome. With this platform, 890 proteins with diverse physicochemical characteristics were identified; the mitochondrial protein panel encompassed proteins with various functional roles including bioenergetics, protein import, and mitochondrial fusion. Taken together, results of this study provide a large-scale view of the proteome in subsarcolemmal mitochondria from the rat heart, and aid in the selection of optimal bioanalytical platforms for differential protein expression profiling of mitochondria in health and disease. 相似文献
103.
Leopold Weber Wolfgang Lenhardt Franz Möstl Gregor Götzl Julia Weilbold Heinz Reitner 《BHM Berg- und Hüttenm?nnische Monatshefte》2016,161(4):148-155
Touristic mines are by far not only of public interest. During guided tours the importance of mining and mineral resources for society can be explained in a proper way. Mineral deposits, for long time not accessible and only known from old literature can now be studied in detail by scientists. Old underground mines can be used for different purposes. With respect to Arzberg the different possibilities of utilization of old underground workings are described in detail: A touristic mine serves not only as an attraction, but also as a training centre for underground geological mapping, geochemistry and geophysics research laboratory of universities. For many years the ZAMG (Central Institute for Meteorology and Geodynamics) has been operating a seismic station, and parts of the old mine workings have been used for cheese refinery since 2006. Furthermore, the mine water is utilized for extracting geothermal energy and serves the cooling chambers. The combined use of the old mine workings by different parties permits sharing the substantial maintenance costs. 相似文献
104.
Gustavo Alberto Polenta Dorcas Weber Samuel Godefroy-Benrejeb Michael Abbott 《Food Analytical Methods》2012,5(2):216-225
The present study evaluates the effect of food processing on the antigenicity of pecan proteins as measured by enzyme-linked
immunosorbent assay (ELISA). In addition, proteomic tools were used to identify potential pecan markers suitable for confirming
the presence of pecan proteins in food and validating new methods developed to detect traces of the commodity. To assess the
effects of processing on protein stability and antigenicity, pecan nuts were submitted to heat treatments and extracts were
analysed by ELISA, sodium dodecyl sulphate polyacrylamide gel electrophoresis and Western blot. The ELISA method was able
to detect pecan traces even after submitting the commodity to rigorous treatments, though these treatments affected the detectability
to varying degrees. Proteomic assessment showed that the majority of pecan proteins were matched by homology to walnut proteins,
which are more abundantly populated in the protein sequence databases. However, there were a few important exceptions: 7S vicilin, 11S legumin and putative allergen I1, unambiguously identified as pecan in origin. Interestingly, putative allergen I1 offered unique analytical advantages to be used as a pecan marker for validation and confirmation purposes. 相似文献
105.
Differential effects of air conditioning type on residential endotoxin levels in a semi‐arid climate 下载免费PDF全文
J. D. Johnston B. A. Kruman M. C. Nelson R. M. Merrill R. J. Graul T. G. Hoybjerg S. C. Tuttle S. J. Myers R. B. Cook K. S. Weber 《Indoor air》2017,27(5):946-954
Residential endotoxin exposure is associated with protective and pathogenic health outcomes. Evaporative coolers, an energy‐efficient type of air conditioner used in dry climates, are a potential source of indoor endotoxins; however, this association is largely unstudied. We collected settled dust biannually from four locations in homes with evaporative coolers (n=18) and central air conditioners (n=22) in Utah County, Utah (USA), during winter (Jan‐Apr) and summer (Aug‐Sept), 2014. Dust samples (n=281) were analyzed by the Limulus amebocyte lysate test. Housing factors were measured by survey, and indoor temperature and relative humidity measures were collected during both seasons. Endotoxin concentrations (EU/mg) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons. Endotoxin surface loads (EU/m2) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons and in upholstered furniture during winter. For the nine significant season‐by‐location comparisons, EU/mg and EU/m2 were approximately three to six times greater in homes using evaporative coolers. A plausible explanation for these findings is that evaporative coolers serve as a reservoir and distribution system for Gram‐negative bacteria or their cell wall components in homes. 相似文献
106.
Kostli K.P. Frauchiger D. Niederhauser J.J. Paltauf G. Weber H.P. Frenz M. 《IEEE journal of selected topics in quantum electronics》2001,7(6):918-923
A novel three-dimensional (3-D) computational algorithm to reconstruct 3-D optoacoustic images from two-dimensional (2-D) pressure distributions generated at the sample surface is presented. The 2-D pressure distributions were measured as images at different delay times after the excitation laser pulse. The pressure images were captured with a gated CCD camera as the local pressure induces intensity changes of a reflected probe beam at the surface of the irradiated sample. The illumination time was 10 ns and the resolution of the surface pressure image was 20 μm. The reconstruction algorithm is based on the decomposition into plane waves. The algorithm was tested in the back projection of simulated pressure transients of three sources, and applied to different biological systems. Furthermore the algorithm was compared with the time of flight back projection algorithm. Optoacoustic images with a depth resolution of 15 μm and a lateral resolution of 100 μm are presented 相似文献
107.
Peter K. Farayibi Frederic van gen Hassend Michael Blüm Sebastian Weber 《工业材料与腐蚀》2021,72(9):1529-1546
Martensitic stainless steel powder exhibits a high nitrogen uptake when densified by supersolidus liquid-phase sintering in a nitrogen atmosphere, but the optimum uptake, which is beneficial to its resistance to corrosion, is unknown. In this study, the resistance of high-carbon martensitic stainless steel X190CrVMo20-4-1 densified in a nitrogen atmosphere against pitting corrosion was explored. This was to clarify the impact of nitrogen uptake in the steel matrix in the quenched and tempered condition on its corrosion resistance in an aqueous solution. Samples were subjected to potentiodynamic polarisation tests in a de-aerated, 1 wt% NaCl solution. Results revealed that the X190 steel densified in a nitrogen atmosphere at 40-kPa pressure, subjected to deep cryogenic treatment in liquid nitrogen at an austenitising temperature of 1150°C and tempered at 200°C, had the best pitting corrosion resistance with a breakdown potential of 142 ± 11 mV/SCE and a hardness of 738 ± 4 HV10. The matrix around the M7C3 carbides and MX carbonitrides suffered high pitting susceptibility. The implications of this study serve as a basis for the improvement of the functional properties of steels. 相似文献
108.
Structure and Thermal Expansion of YSZ and La2Zr2O7 Above 1500°C from Neutron Diffraction on Levitated Samples 下载免费PDF全文
Sergey V. Ushakov Alexandra Navrotsky Richard J. K. Weber Joerg C. Neuefeind 《Journal of the American Ceramic Society》2015,98(10):3381-3388
High‐temperature time‐of‐flight neutron diffraction experiments were performed on cubic yttria‐stabilized zirconia (YSZ, 10 mol% YO1.5) and lanthanum zirconate (LZ) prepared by laser melting. Three spheroids of each composition were aerodynamically levitated and rotated in argon flow and heated with a CO2 laser. Unit cell, positional and atomic displacement parameters were obtained by Rietveld analysis. Below ~1650°C the mean thermal expansion coefficient (TEC) for YSZ is higher than for LZ (13 ± 1 vs. 10.3 ± 0.6) × 10?6/K. From ~1650°C to the onset of melting of LZ at ~2250°C, TEC for YSZ and LZ are similar and within (7 ± 2) × 10?6/K. LZ retains the pyrochlore structure up to the melting temperature with Zr coordination becoming closer to perfectly octahedral. Congruently melting LZ is La deficient. The occurrence of thermal disordering of oxygen sublattice (Bredig transition) in defect fluorite structure was deduced from the rise in YSZ TEC to ~25 × 10?6/K at 2350°C–2550°C with oxygen displacement parameters (Uiso) reaching 0.1 Å2, similar to behavior observed in UO2. Acquisition of powder‐like high‐temperature neutron diffraction data from solid‐levitated samples is feasible and possible improvements are outlined. This methodology should be applicable to a wide range of materials for high‐temperature applications. 相似文献
109.
In spite of its great importance for the dry classification of fine powders, the processes in deflector wheel classifiers are to a large extent unknown. Therefore, in the present work a commercial available classifier was modified to gain an optical access to the deflector wheel. For the first time, the obtained photographs enable an observation of the gas flow and the particle motion between the blades of the deflector wheel. Especially the importance of particle‐particle‐ and particle‐blade‐collisions could be shown. 相似文献
110.
Beyond Cognitive Framing Processes: Anger Mediates the Effects of Responsibility Framing on the Preference for Punitive Measures 下载免费PDF全文
A new stream of research indicates that framing effects are based on emotional as well as cognitive processes. However, it is not entirely clear whether emotions mediate framing effects and what the moderators of emotional mediation processes are. To address these questions, we conducted an experiment in which the framing of responsibility for a social problem was manipulated (ambivalent vs. high‐responsibility frame). We find that the high‐responsibility frame increased the preference for punitive measures by increasing responsibility beliefs and eliciting anger. Furthermore, we find that trait anger moderates the framing effect on anger and that responsibility beliefs are positively associated with anger intensity. The significance of these findings for framing research and suggestions for future studies are discussed. 相似文献