全文获取类型
收费全文 | 7365篇 |
免费 | 216篇 |
国内免费 | 30篇 |
专业分类
电工技术 | 110篇 |
综合类 | 2篇 |
化学工业 | 1527篇 |
金属工艺 | 299篇 |
机械仪表 | 193篇 |
建筑科学 | 106篇 |
矿业工程 | 8篇 |
能源动力 | 341篇 |
轻工业 | 304篇 |
水利工程 | 61篇 |
石油天然气 | 15篇 |
无线电 | 1047篇 |
一般工业技术 | 1583篇 |
冶金工业 | 872篇 |
原子能技术 | 85篇 |
自动化技术 | 1058篇 |
出版年
2023年 | 73篇 |
2022年 | 162篇 |
2021年 | 202篇 |
2020年 | 172篇 |
2019年 | 165篇 |
2018年 | 258篇 |
2017年 | 215篇 |
2016年 | 210篇 |
2015年 | 120篇 |
2014年 | 223篇 |
2013年 | 429篇 |
2012年 | 258篇 |
2011年 | 351篇 |
2010年 | 251篇 |
2009年 | 298篇 |
2008年 | 265篇 |
2007年 | 220篇 |
2006年 | 217篇 |
2005年 | 169篇 |
2004年 | 134篇 |
2003年 | 136篇 |
2002年 | 139篇 |
2001年 | 131篇 |
2000年 | 132篇 |
1999年 | 119篇 |
1998年 | 267篇 |
1997年 | 186篇 |
1996年 | 135篇 |
1995年 | 137篇 |
1994年 | 110篇 |
1993年 | 137篇 |
1992年 | 111篇 |
1991年 | 99篇 |
1990年 | 84篇 |
1989年 | 77篇 |
1988年 | 72篇 |
1987年 | 75篇 |
1986年 | 89篇 |
1985年 | 106篇 |
1984年 | 99篇 |
1983年 | 96篇 |
1982年 | 78篇 |
1981年 | 63篇 |
1980年 | 49篇 |
1979年 | 46篇 |
1978年 | 49篇 |
1977年 | 62篇 |
1976年 | 82篇 |
1975年 | 43篇 |
1973年 | 42篇 |
排序方式: 共有7611条查询结果,搜索用时 15 毫秒
41.
Artificial intelligence (AI) has been heralded by many as the next source of business value. Grounded on the resource-based theory of the firm and on recent work on AI at the organizational context, this study (1) identifies the AI-specific resources that jointly create an AI capability and provides a definition, (2) develops an instrument to capture the AI capability of the firms, and (3) examines the relationship between an AI capability and organizational creativity and performance. Findings empirically support the suggested theoretical framework and corresponding instrument and provide evidence that an AI capability results in increased organizational creativity and performance. 相似文献
42.
Sharma Pooja Dinkar Shail Kumar Gupta D. V. 《Neural computing & applications》2021,33(19):13123-13143
Neural Computing and Applications - This work presents an efficient hybridized approach for the classification of electrocardiogram (ECG) samples into crucial arrhythmia classes to detect heartbeat... 相似文献
43.
In this paper, the authors address the problem of edge-perception for its applications to vision-feedback control in robotic systems.In natural vision, the recognition of objects takes place through the process consisting of eye system, neural networks and cognition. The cognitive process, in turn yields a phenomenon known as perception. This is the phenomenon of perception of physical attributes, such as edges, color and texture, etc., which is responsible for the recognition of objects through the natural vision processes.In this paper, we make an attempt to postulate the theory of perception for gray-level images. The gray-level images, when going through the cognitive and perception processes, are contaminated by the uncertainty; here we call it cognitive uncertainty.The studies in this paper are confined to the phenomenon of edge-perception for two-dimensional gray-level images, however, these studies can be extended to other types of visual attributes both in two-dimensional and three-dimensional spaces. Indeed, the perception of these attributes, which attempts to emulate the human vision system, may help in the design of a truly robust computer vision-feedback control system for robotic applications. 相似文献
44.
Lotka's law and productivity patterns of entomological research in Nigeria for the period, 1900–1973
D. K. Gupta 《Scientometrics》1987,12(1-2):33-46
A bibliography of entomological research in Nigeria, 1900–1973 totally 1720 publications was analysed to study the author productivity patterns and to test the applicability of Lotka's law for the obtained distributions. Four different files were generated, one for the publications of all the authors, second for the publications by first authors, third for single authors and fourth for coauthors. Lotka's law in its original form as inverse square law does not apply to any of the four data sets. However, it does apply in its generalised form with the calculated values of characteristic exponent . The values of were found to be 1.9, 1.8, 2.2 and 2.4 for the four different data sets. K-S statistical test was aplied to test the applicability of generalised form of Lotka's law. The maximum difference in the observed and estimated values of the proportions of authors was found to be highly insignificant at 0.01 level of significance in each of the four cases. 相似文献
45.
46.
Journal of Computational Electronics - A novel integrated design and simulation approach is applied to analyze the performance of a metal–oxide–semiconductor field-effect transistor... 相似文献
47.
R. Gupta G. S. Sekhon K. S. Shishodia 《Journal of Materials Processing Technology》1997,70(1-3):274-278
The grinding operation is considered to be equivalent to a moving band source of heat and mechanical load on the surface of a semi-infinite solid, producing very high temperature on the surface of the workpiece. The resulting temperature may result in high stress in the workpiece. It is thus desirable to be able to predict the stress levels expected during the grinding process. 相似文献
48.
Silicon - We investigate the performance of a dielectric modulated dual-metal double-gate with low-k/high-k oxide stack junctionless MOSFET (DM-DG-LK/HK-S JL-MOSFET) based sensor device for... 相似文献
49.
Farrukh Aqil Jeyaprakash Jeyabalan Radha Munagala Iqbal Ahmad David J. Schultz Ramesh C. Gupta 《International journal of molecular sciences》2021,22(12)
Breast cancer (BC) is a leading cause of cancer deaths in women in less developed countries and the second leading cause of cancer death in women in the U.S. In this study, we report the inhibition of E2-mediated mammary tumorigenesis by Cuminum cyminum (cumin) administered via the diet as cumin powder, as well as dried ethanolic extract. Groups of female ACI rats were given either an AIN-93M diet or a diet supplemented with cumin powder (5% and 7.5%, w/w) or dried ethanolic cumin extract (1%, w/w), and then challenged with subcutaneous E2 silastic implants (1.2 cm; 9 mg). The first appearance of a palpable mammary tumor was significantly delayed by both the cumin powder and extract. At the end of the study, the tumor incidence was 96% in the control group, whereas only 55% and 45% animals had palpable tumors in the cumin powder and extract groups, respectively. Significant reductions in tumor volume (660 ± 122 vs. 138 ± 49 and 75 ± 46 mm3) and tumor multiplicity (4.21 ± 0.43 vs. 1.16 ± 0.26 and 0.9 ± 0.29 tumors/animal) were also observed by the cumin powder and cumin extract groups, respectively. The cumin powder diet intervention dose- and time-dependently offset E2-related pituitary growth, and reduced the levels of circulating prolactin and the levels of PCNA in the mammary tissues. Mechanistically, the cumin powder diet resulted in a significant reversal of E2-associated modulation in ERα, CYP1A1 and CYP1B1. Further, the cumin powder diet reversed the expression levels of miRNAs (miR-182, miR-375, miR-127 and miR-206) that were highly modulated by E2 treatment. We analyzed the composition of the extract by GC/MS and established cymene and cuminaldehyde as major components, and further detected no signs of gross or systemic toxicity. Thus, cumin bioactives can significantly delay and prevent E2-mediated mammary tumorigenesis in a safe and effective manner, and warrant continued efforts to develop these clinically translatable spice bioactives as chemopreventives and therapeutics against BC. 相似文献
50.
Low-Thermal-Conductivity Rare-Earth Zirconates for Potential Thermal-Barrier-Coating Applications 总被引:9,自引:0,他引:9
Jie Wu Xuezheng Wei Nitin P. Padture Paul G. Klemens Maurice Gell Eugenio García Pilar Miranzo Maria I. Osendi 《Journal of the American Ceramic Society》2002,85(12):3031-3035
Rare-earth zirconates have been identified as a class of low-thermal-conductivity ceramics for possible use in thermal barrier coatings (TBCs) for gas-turbine engine applications. To document and compare the thermal conductivities of important rare-earth zirconates, we have measured the thermal conductivities of the following hot-pressed ceramics: (i) Gd2 Zr2 O7 (pyrochlore phase), (ii) Gd2 Zr2 O7 (fluorite phase), (iii) Gd2.58 Zr1.57 O7 (fluorite phase), (iv) Nd2 Zr2 O7 (pyrochlore phase), and (v) Sm2 Zr2 O7 (pyrochlore phase). We have also measured the thermal conductivity of pressureless-sintered 7 wt% yttria-stabilized zirconia (7YSZ)—the commonly used composition in current TBCs. All rare-earth zirconates investigated here showed nearly identical thermal conductivities, all of which were ∼30% lower than the thermal conductivity of 7YSZ in the temperature range 25°–700°C. This finding is discussed qualitatively with reference to thermal-conductivity theory. 相似文献