全文获取类型
收费全文 | 1854篇 |
免费 | 77篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 32篇 |
综合类 | 2篇 |
化学工业 | 509篇 |
金属工艺 | 77篇 |
机械仪表 | 47篇 |
建筑科学 | 53篇 |
矿业工程 | 14篇 |
能源动力 | 105篇 |
轻工业 | 100篇 |
水利工程 | 17篇 |
石油天然气 | 4篇 |
无线电 | 210篇 |
一般工业技术 | 385篇 |
冶金工业 | 138篇 |
原子能技术 | 62篇 |
自动化技术 | 188篇 |
出版年
2024年 | 7篇 |
2023年 | 37篇 |
2022年 | 78篇 |
2021年 | 91篇 |
2020年 | 69篇 |
2019年 | 57篇 |
2018年 | 84篇 |
2017年 | 69篇 |
2016年 | 86篇 |
2015年 | 50篇 |
2014年 | 80篇 |
2013年 | 131篇 |
2012年 | 78篇 |
2011年 | 109篇 |
2010年 | 88篇 |
2009年 | 89篇 |
2008年 | 83篇 |
2007年 | 90篇 |
2006年 | 56篇 |
2005年 | 38篇 |
2004年 | 41篇 |
2003年 | 37篇 |
2002年 | 32篇 |
2001年 | 22篇 |
2000年 | 23篇 |
1999年 | 21篇 |
1998年 | 34篇 |
1997年 | 14篇 |
1996年 | 27篇 |
1995年 | 29篇 |
1994年 | 7篇 |
1993年 | 14篇 |
1992年 | 14篇 |
1991年 | 20篇 |
1990年 | 16篇 |
1989年 | 23篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 3篇 |
排序方式: 共有1943条查询结果,搜索用时 15 毫秒
31.
Li Wei Joseph Raj Alex Noel Tjahjadi Tardi Zhuang Zhemin 《Applied Intelligence》2022,52(13):15164-15176
Applied Intelligence - The retina is one of the most developed sensing organs in the human body. However, the knowledge on the coding and decoding of the retinal neurons are still rather limited.... 相似文献
32.
Bodaballa Avinash Ravipati Venu Tollamadugu N.V.K.V. Prasad Mekapogu Alpha Raj Kothapalli Srinivasa Rao Chintamaneni Srilatha 《IET nanobiotechnology / IET》2017,11(4):383
The utility of green silver nanoparticles (AgNPs) in veterinary medicine is steadily increasing as they have many therapeutic applications against pathogens and arthropods of livestock. In this study, green AgNPs using neem (N‐AgNPs), 2,3‐dehydrosalanol (2,3‐DHS‐AgNPs) and quercetin dihydrate (QDH‐AgNPs) were synthesised and characterised. Synthesised compounds were characterised by UV‐Vis spectroscopy and the peak absorbance was recorded at 370 nm for neem extract. For N‐AgNPs, 2,3‐DHS‐AgNPs and QDH‐AgNPs, the maximum absorbance peaks were at 430, 230 and 220 nm, respectively. The FTIR analysis confirmed the synthesis of green AgNPs. The XRD pattern of N‐AgNPs showed the peaks corresponding to whole spectra of 2 θ values ranging from 10–80. The relatively higher intensity of (111, 222) planes in face centred cubic crystalline structure supports the formation of synthesised AgNPs. In DLS analysis, the hydrodynamic diameter of neem leaf extract was found to be 259.8 nm, followed by 5.3, 6.7 and 261.8 nm for 2,3‐DHS‐AgNPs, N‐AgNPs and QDH‐AgNPs, respectively. Based on the transmission electron microscopy and scanning electron microscopy image analyses, confirmed the formation of N‐AgNPs, 2,3‐DHS‐AgNPs and QDH‐AgNPs. These eco‐friendly phyto‐AgNPs may be of use as an effective alternative to chemical control methods against the arthropods of livestock.Inspec keywords: nanoparticles, silver, nanomedicine, biomedical materials, nanofabrication, Fourier transform infrared spectra, ultraviolet spectra, visible spectra, X‐ray diffraction, light scattering, transmission electron microscopy, scanning electron microscopy, aggregation, veterinary medicineOther keywords: 2,3‐dehydrosalanol mediated silver nanoparticles, quercetin dihydrate mediated silver nanoparticles, therapeutic applications, green silver nanoparticles, veterinary medicine, Azadirachta indica, UV‐visible spectroscopy, Fourier transformed infrared analysis, X‐ray diffraction, (111) planes, (222) planes, face centred cubic crystalline structure, dynamic light scattering, hydrodynamic diameter, aqueous neem leaf extract, transmission electron microscopy, hexagonal shape, pencil head shape, cuboid shape, scanning electron microscopy, aggregation, arthropod infesting livestock, Ag, in‐vivo antiectoparasitic activity, in‐vitro antiectoparasitic activity 相似文献
33.
Shiva Raj Singh 《Expert systems with applications》2009,36(7):10551-10559
This paper presents a computational method of forecasting based on high-order fuzzy time series. The developed computational method provides a better approach to overcome the drawback of existing high-order fuzzy time series models. Its simplicity lies with the use of differences in consecutive values of various orders as forecasting parameter and a w-step fuzzy predictor in place of complicated computations of fuzzy logical relations. The objective of the present study is to examine the suitability of various high-order fuzzy time series models in forecasting. The general suitability of the developed method has been tested by implementing it in the forecasting of student enrollments of the University of Alabama and in the forecasting of crop (Lahi) production, a case of high uncertainty in time series data. The results obtained have been compared in terms of average error of forecast to show superiority of the proposed model. 相似文献
34.
Nelsestuen GL Harvey SB Zhang Y Kasthuri RS Sinaiko AR Ely EW Bernard GR Homoncik M Jilma B 《Proteomics. Clinical applications》2008,2(2):158-166
Although numerous protein biomarkers have been correlated with advanced disease states, no new clinical assays have been developed. Goals often anticipate disease-specific protein changes that exceed values among healthy individuals, a property common to acute phase reactants. This review considers somewhat different approaches. It focuses on intact protein isoform ratios that present a biomarker without change in the total concentration of the protein. These will seldom be detected by peptide level analysis or by most antibody-based assays. For example, application of an inexpensive method to large sample groups resulted in observation of several polymorphisms, including the first structural polymorphism of apolipoprotein C1. Isoform distribution of this protein was altered and was eventually linked to increased obesity. Numerous other protein isoforms included C- and N-terminal proteolysis, changes of glycoisoform ratios and certain types of sulfhydryl oxidation. While many of these gave excellent statistical correlation with advanced disease, clinical utility was not apparent. More important may be that protein isoform ratios were very stable in each individual. Diagnosis by longitudinal analysis of the same individual might increase sensitivity of protein biomarkers by 20-fold or more. Protein changes that exceed the range of values found among healthy individuals may be uncommon. 相似文献
35.
Ken Maynard Patrick Moss Marcus Whitehead S. Narayanan Matt Garay Nathan Brannon Raj Gopal Kantamneni & Todd Kustra 《Expert Systems》2001,18(2):88-98
Although developments on software agents have led to useful applications in automation of routine tasks such as electronic mail filtering, there is a scarcity of research that empirically evaluates the performance of a software agent versus that of a human reasoner, whose problem-solving capabilities the agent embodies. In the context of a game of a chance, namely Yahtzee©, we identified strategies deployed by expert human reasoners and developed a decision tree for agent development. This paper describes the computer implementation of the Yahtzee game as well as the software agent. It also presents a comparison of the performance of humans versus an automated agent. Results indicate that, in this context, the software agent embodies human expertise at a high level of fidelity. 相似文献
36.
R. Raj I. E. Raj D. M. Frangopol J. S. Kong 《Metallurgical and Materials Transactions A》2004,35(5):1471-1476
The lifetime of high-temperature systems is often controlled by thermally activated mechanisms such as diffusion. The variability
in the lifetime of such systems is analyzed when the operating temperature varies according to a normal (Gaussian) distribution.
Linear approximation analysis is employed to obtain simple closed form results for the probability density function (pdf)
for the lifetime. The Gaussian variation in temperature is shown to transform to a log-normal distribution for the lifetime.
The standard deviation of the log-normal distribution can be predicted from the activation energy, the peak temperature, and
the standard deviation of the temperature distribution. Higher activation energy and lower operating temperature increase
the variability of the lifetime. This approximate result is compared with the exact transformation. Lifetime experiments with
incandescent tungsten lamps are compared to the theoretical prediction. 相似文献
37.
Deepu Talla Hung C.-Y. Raj Talluri Brill F. Smith D. Brier D. Xiong B. Huynh D. 《Micro, IEEE》2004,24(2):32-39
Portable devices equipped with imaging, video, and audio functionality are proliferating rapidly, and manufacturers are shipping hundreds of millions of such devices. A general-purpose processor (GPP) typically consumes tens of watts to nearly a hundred watts, while a high-performance digital still cameras main processor consumes only hundreds of milliwatts to nearly half a watt. Designing a mediaprocessor with performance comparable to that of a GPP at a power budget two orders of magnitude lower and a cost more than an order of magnitude lower poses quite a challenge. To meet requirements and reduce overall system cost, mediaprocessor designers must integrate the device with an extensive set of peripherals. For performance, cost, and power reasons, application-specific integrated circuits have traditionally been the most popular choice for portable media systems. We discuss the architecture of the DM310, a highly integrated portable digital mediaprocessor, manufactured in a 0.13-micron process. 相似文献
38.
U. Kamachi Mudali H. S. Khatak Baldev Raj M. Uhlemann 《Materials and Manufacturing Processes》2004,19(1):61-73
It is well known that the addition of nitrogen to steels and stainless steels enhances the passivity and localized corrosion resistance, in addition to improving the mechanical properties. Selective alloying of surfaces of steels and stainless steels with nitrogen could also enhance the corrosion resistance and improve the mechanical properties without affecting the bulk properties. Techniques like ion implantation, laser alloying, nitriding, etc. can be effectively used to introduce very high levels of nitrogen. In addition, these techniques can also produce modified surfaces with novel microstructures to further improve the properties. The surface alloying methods also provide an opportunity to selectively nitrogenate the surface of finished components in order to obtain better properties. The review highlights the techniques, modifications and the properties obtained further. 相似文献
39.
Raj V. Siddharthan Vela Ganeshwara Bruce L. Kutter Magdy El-Desouky Robert V. Whitman 《Canadian Metallurgical Quarterly》2004,130(1):26-35
A relatively simple rigid plastic multiblock computational model has been developed to predict the permanent seismic displacement of mechanically stabilized earth (MSE) walls. The model formulation was based on many observations made from a series of centrifuge tests carried out on many different configurations of MSE walls. The proposed model is similar to the sliding block method of Newmark. The approach accounted for the variation in acceleration within the backfill and the nonuniform nature of the permanent wall face deformation. The predictive capability of the proposed model has been verified using centrifuge test results obtained for four MSE walls each subjected to three earthquake excitations with strength varying between 0.48 and 0.9g. The analytical model captures many aspects of the characteristic deformation behavior of MSE walls observed in the centrifuge tests. In each of the eleven wall displacement cases studied, the backfill friction angle that yielded a good match between the computed and measured maximum wall displacement was consistent with the corresponding laboratory measured values. 相似文献
40.
Raj Munshi Suhail Ahmad 《Hemodialysis international. International Symposium on Home Hemodialysis》2014,18(1):172-174
Rapid removal of small molecules during hemodialysis places an acutely ill patient with kidney failure at an increased risk of hemodynamic instability and for dialysis disequilibrium syndrome. The use of high‐flux, high‐efficiency (HEF) dialyzers may increase this risk despite reductions in blood and dialysate flow. We performed in vitro experiments to compare urea clearance at low dialysate flow and various blood flows using a low‐efficiency low‐flux (LEF) and a HEF membrane. Compared to LEF, there was a significant increase in the clearance of urea at all blood flows with the HEF (all P values < 0.005). HEF dialyzer (F180NR) had higher urea clearance at a blood flow of 150 mL/min than LEF dialyzer (F5) at blood flow of 300 mL/min (144.1 ± 0.99 vs. 130.1 ± 0.001 mL/min for F180 vs. F5, respectively, P < 0.002). Our data suggest that use of HEF dialyzer are not as safe as LEF in high‐risk acute dialysis patients since these are associated with more rapid removal of urea despite reduction in blood and dialysate flow as compared to LEF. 相似文献