全文获取类型
收费全文 | 1279篇 |
免费 | 77篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 16篇 |
综合类 | 1篇 |
化学工业 | 295篇 |
金属工艺 | 16篇 |
机械仪表 | 34篇 |
建筑科学 | 19篇 |
矿业工程 | 2篇 |
能源动力 | 27篇 |
轻工业 | 126篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 291篇 |
一般工业技术 | 252篇 |
冶金工业 | 176篇 |
原子能技术 | 6篇 |
自动化技术 | 100篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 21篇 |
2021年 | 32篇 |
2020年 | 15篇 |
2019年 | 25篇 |
2018年 | 35篇 |
2017年 | 31篇 |
2016年 | 33篇 |
2015年 | 21篇 |
2014年 | 43篇 |
2013年 | 59篇 |
2012年 | 56篇 |
2011年 | 98篇 |
2010年 | 55篇 |
2009年 | 50篇 |
2008年 | 77篇 |
2007年 | 62篇 |
2006年 | 50篇 |
2005年 | 35篇 |
2004年 | 32篇 |
2003年 | 43篇 |
2002年 | 44篇 |
2001年 | 31篇 |
2000年 | 43篇 |
1999年 | 36篇 |
1998年 | 52篇 |
1997年 | 52篇 |
1996年 | 39篇 |
1995年 | 17篇 |
1994年 | 20篇 |
1993年 | 25篇 |
1992年 | 16篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1364条查询结果,搜索用时 46 毫秒
71.
Jung-Won Sub Kwang-Myoung Rho Chan-Kwang Park Yo-Hwan Koh 《Solid-State Circuits, IEEE Journal of》1996,31(7):1025-1028
A new offset-trimming bit-line sensing scheme is described which is suitable for gigabit-scale DRAM's. This sensing scheme can suppress the sensitivity degradation caused by the large electrical parameter variation of deep submicron transistors. The effective offset voltage dependence on trimming time is analyzed and verified with simulation results. As compared with a conventional direct sensing scheme, the proposed scheme shows remarkable improvement on the sensitivity. A test device was fabricated with a 0.25 μm CMOS technology and its measurement results indicate the successful operation of offset-trimming 相似文献
72.
Used multiple word lists with low contextual constraints to examine nonorganizational processes or "strategies" which might be operating in single-trial free recall by schizophrenics. Ss were 20 young nonpsychotic schizophrenics and 20 normal controls. The schizophrenics, as compared to the normals, showed limited storage capacities of the primary and secondary memories, vulnerability to intrusion, slow response time, inefficiency in utilizing stimulus contiguity for organization, and consequential recall deficit. These findings, with those from previous investigations, suggest that both organizational and nonorganizational dysfunctions may underlie the schizophrenics' poor performance. The possibility that nonorganizational processes may be integral parts of mnemonic organization is discussed. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
Thermal conductivity and electrical resistivity of porous materials, including 304L stainless steel Rigimesh, 304L stainless steel sintered spherical powders, and OFHC sintered spherical powders at different porosities and temperatures are reported and correlated. It was found that the thermal conductivity and electrical resistivity can be related to the solid material properties and the porosity of the porous matrix regardless of the matrix structure. It was also found that the modified Wiedemann-Franz-Lorenz relationship is valid for the porous materials under consideration. For high conductivity materials, the Lorenz function and the lattice component of conductivity depend on the material and are independent of the porosity. For low conductivity, the lattice component depends on the porosity as well. 相似文献
74.
75.
This article compares empirically the major factors affecting blinded and sighted reviewers in the selection of research proposals to be funded in a "scientifically small" country. Fisher's Z-test shows that the applicant characteristics (rank of undergraduate school where the applicant studied, professional age of the applicant, and academic recognition of the applicant) are the major factors leading to the significantly different evaluation scores between blinded and sighted reviewers. This means that "open" evaluation of research proposals is obviously biased. Policy implications of the findings and future research directions are discussed. 相似文献
76.
Adrenal insufficiency presenting as unexplained hypotension in nocturnal home hemodialysis
下载免费PDF全文
![点击此处可从《Hemodialysis international. International Symposium on Home Hemodialysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Timothy Jee Kam Koh Christopher T. Chan 《Hemodialysis international. International Symposium on Home Hemodialysis》2016,20(3):E10-E13
Adrenal insufficiency is a complication of chronic corticosteroid therapy. Unexplained hypotension may be a manifestation of an adrenal insufficient state in patients with a history of corticosteroid therapy on hemodialysis. We present a series of five cases of patients on nocturnal home hemodialysis with hypotension as the main manifestation of adrenal insufficiency. Unexplained hypotension in patients with a history of corticosteroid therapy should prompt the managing clinician to consider adrenal insufficiency as a possible cause. 相似文献
77.
Nanoporous Gold Bowls: A Kinetic Approach to Control Open Shell Structures and Size‐Tunable Lattice Strain for Electrocatalytic Applications
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Srikanth Pedireddy Hiang Kwee Lee Charlynn Sher Lin Koh Joel Ming Rui Tan Weng Weei Tjiu Xing Yi Ling 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(33):4531-4540
Controlling sub‐10 nm ligament sizes and open‐shell structure in nanoporous gold (NPG) to achieve strained lattice is critical in enhancing catalytic activity, but it remains a challenge due to poor control of reaction kinetics in conventional dealloying approach. Herein, a ligament size‐controlled synthesis of open‐shell NPG bowls (NPGB) through hetero‐epitaxial growth of NPGB on AgCl is reported. The ligament size in NPGB is controlled from 6 to 46 nm by varying the hydroquinone to HAuCl4 ratio. The Williamson–Hall analysis demonstrates a higher lattice strain in smaller ligament size. In particular, NPGB with 6 nm (NPGB 6) ligament size possess the highest strain of 15.4 × 10?3, which is nearly twice of conventional 2D NPG sheets (≈8.8 × 10?3). The presence of high surface energy facets in NPGBs is also envisaged. The best electrocatalytic activity toward methanol oxidation is observed in NPGB 6 (27.8 μA μg?1), which is ≈9‐fold and 3‐fold higher than 8 nm solid Au nanoparticles, and conventional NPG sheets. The excellent catalytic activity in NPGB 6 is attributed to the open‐shell structure, lattice strain, and higher electro‐active surface area, allowing efficient exposure of catalytic active sites to facilitate the methanol oxidation. The results offer a potential strategy for designing next generation electrocatalysts. 相似文献
78.
Yongsik Jeong Lei Wang Haein Shin Sang-Mo Koh Gyesoon Park 《International journal of remote sensing》2013,34(21):7225-7250
ABSTRACTWe introduce a cost-effective reflectance calibration method for small unmanned aerial vehicle (sUAV) images using ethylene-vinyl acetate (EVA) greyscale reference panels. The goal is to test if such light-weight and low-cost panels can provide sufficient calibration accuracy to support UAV survey projects. The universal calibration equations to convert red-green-blue (RGB) digital number (DN) values of UAV images to surface reflectance values were constructed based on the relationship between RGB values measured by a colour digitizer and surface reflectance values measured by a spectrometer. We compared the calibration results for UAV ortho-mosaic images acquired at three different illumination conditions in late autumn to the results derived from high-cost commercial panels. The comparison showed high degree of agreement between our method using the EVA panels with the traditional methods using the commercial panels. The Mann–Whitney U test verified our method was statistically more significant at all illumination conditions tests. In addition, the calibration results applied for two different sensors and three different flight altitudes acquired in early summer were satisfactory. This method is transferable to various illumination conditions and flight altitudes as long as the effects of shades and the bidirectional reflectance distribution function (BRDF) are minimal. We expect our research could expedite sUAV image calibration by lowering its cost and levelling its availability. 相似文献
79.
Low distortion speech enhancement 总被引:5,自引:0,他引:5
An innovative approach to speech enhancement is illustrated which minimises distortion to the underlying speech during the noise-reduction process. The key to this approach lies in the identification of whether the additive noise for a particular frequency component is constructive or destructive. Once this can be identified both multiplicative and subtractive filters can be derived using the minimum mean-square error criterion. The optimal combination of the proposed multiplicative and subtractive filter is also shown 相似文献
80.
The effects of hydrogen (protium) or deuterium absorption∕desorption cycling on the strength and hardness of well-annealed palladium have been evaluated in this study. The results indicate that absorption followed by complete desorption of hydrogen or deuterium increases the strength and hardness characteristics of the palladium matrix while decreasing the metal's ductility. Increasing the amount of hydrogen or deuterium during absorption leads to more pronounced effects on the strength, hardness, and ductility of palladium. The effects of hydrogen absorption∕desorption are more pronounced than those of deuterium absorption∕desorption. The observed results have been explained in terms of the generation of dislocations during hydrogen or deuterium cycling. 相似文献