全文获取类型
收费全文 | 4707篇 |
免费 | 309篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 50篇 |
综合类 | 5篇 |
化学工业 | 846篇 |
金属工艺 | 218篇 |
机械仪表 | 316篇 |
建筑科学 | 55篇 |
能源动力 | 158篇 |
轻工业 | 359篇 |
水利工程 | 17篇 |
石油天然气 | 2篇 |
无线电 | 853篇 |
一般工业技术 | 963篇 |
冶金工业 | 596篇 |
原子能技术 | 61篇 |
自动化技术 | 527篇 |
出版年
2024年 | 5篇 |
2023年 | 69篇 |
2022年 | 88篇 |
2021年 | 134篇 |
2020年 | 102篇 |
2019年 | 114篇 |
2018年 | 169篇 |
2017年 | 148篇 |
2016年 | 165篇 |
2015年 | 126篇 |
2014年 | 230篇 |
2013年 | 305篇 |
2012年 | 285篇 |
2011年 | 342篇 |
2010年 | 229篇 |
2009年 | 272篇 |
2008年 | 221篇 |
2007年 | 199篇 |
2006年 | 198篇 |
2005年 | 156篇 |
2004年 | 146篇 |
2003年 | 132篇 |
2002年 | 118篇 |
2001年 | 105篇 |
2000年 | 71篇 |
1999年 | 71篇 |
1998年 | 238篇 |
1997年 | 126篇 |
1996年 | 94篇 |
1995年 | 73篇 |
1994年 | 53篇 |
1993年 | 46篇 |
1992年 | 26篇 |
1991年 | 12篇 |
1990年 | 17篇 |
1989年 | 15篇 |
1988年 | 9篇 |
1987年 | 14篇 |
1986年 | 13篇 |
1985年 | 6篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1978年 | 5篇 |
1977年 | 14篇 |
1976年 | 23篇 |
1975年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有5026条查询结果,搜索用时 15 毫秒
91.
Sungho Shin Seonjeong Lee Sunyoung Choi Narae Park Yumi Kwon Jaehoon Jeong Shinyeong Ju Yunsil Chang Kangsik Park Chulwon Ha Cheolju Lee 《International journal of molecular sciences》2022,23(12)
Co-culture system, in which two or more distinct cell types are cultured together, is advantageous in that it can mimic the environment of the in vivo niche of the cells. In this study, we presented a strategy to analyze the secretome of a specific cell type under the co-culture condition in serum-supplemented media. For the cell-specific secretome analysis, we expressed the mouse mutant methionyl-tRNA synthetase for the incorporation of the non-canonical amino acid, azidonorleucine into the newly synthesized proteins in cells of which the secretome is targeted. The azidonorleucine-tagged secretome could be enriched, based on click chemistry, and distinguished from any other contaminating proteins, either from the cell culture media or the other cells co-cultured with the cells of interest. In order to have more reliable true-positive identifications of cell-specific secretory bodies, we established criteria to exclude any identified human peptide matched to bovine proteins. As a result, we identified a maximum of 719 secreted proteins in the secretome analysis under this co-culture condition. Last, we applied this platform to profile the secretome of mesenchymal stem cells and predicted its therapeutic potential on osteoarthritis based on secretome analysis. 相似文献
92.
Joonwon Bae Gyo Eun Gu Yeon Ju Kwon Jea Uk Lee Jin-Yong Hong 《International journal of molecular sciences》2022,23(9)
As the control over radioactive species becomes critical for the contemporary human life, the development of functional materials for decontamination of radioactive substances has also become important. In this work, a three-dimensional (3D) porous carbon monolith functionalized with Prussian blue particles was prepared through removal of colloidal silica particles from exfoliated graphene/silica composite precursors. The colloidal silica particles with a narrow size distribution were used to act a role of hard template and provide a sufficient surface area that could accommodate potentially hazardous radioactive substances by adsorption. The unique surface and pore structure of the functionalized porous carbon monolith was examined using electron microscopy and energy-dispersive X-ray analysis (EDS). The effective incorporation of PB nanoparticles was confirmed using diverse instrumentations such as X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). A nitrogen adsorption/desorption study showed that surface area and pore volume increased significantly compared with the starting precursor. Adsorption tests were performed with 133Cs ions to examine adsorption isotherms using both Langmuir and Freundlich isotherms. In addition, adsorption kinetics were also investigated and parameters were calculated. The functionalized porous carbon monolith showed a relatively higher adsorption capacity than that of pristine porous carbon monolith and the bulk PB to most radioactive ions such as 133Cs, 85Rb, 138Ba, 88Sr, 140Ce, and 205Tl. This material can be used for decontamination in expanded application fields. 相似文献
93.
Juyoung Lee Sanghoon Ko Hanbyul Kim Hoonjeong Kwon 《Food science and biotechnology》2011,20(4):1033-1042
The objective of this study was to assess the integrity and intestinal permeability of chitosan nanoparticles (CNPs) in simulated gastrointestinal fluids (SGIF). The cell-associated and transported chitosan was quantified and visualized after incubation of the CNPs with Caco-2 cell monolayer with/without SGIF treatment. In order to establish the role of proteins in the SGIF, CNPs were incubated with 4 proteins having different isoelectric points (pI). CNPs incubated with the fluids did not attach to the cell monolayer in contrast to the intact CNPs. Negatively-charged protein formed the complex with CNPs leading to particle size increase, but protected CNPs from disintegration. In contrary, positively-charged protein interacted with cross-linker causing disintegration of CNPs. CNPs incubated with the fluids did not attach to the cell monolayer in contrast to the intact CNPs. The results suggested that the surface charges of CNPs and proteins play a critical role in structural changes of CNPs in biological environment. 相似文献
94.
Kee Do Woo Jae Hwang Kim Eui Pyo Kwon Min Seok Moon Hyun Bom Lee Tatsuo Sato Zhiguang Liu 《Metals and Materials International》2010,16(2):213-218
To fabricate an Al-V matrix composite reinforced with submicron-sized Al2O3 and AlxVy (Al3V, Al10V) phases, high energy mechanical milling (HEMM) and sintering were employed. By increasing the milling time, the size of mechanically milled powder was significantly reduced. In this study, the average powder size of 59 μm for Al, and 178 μm for V2O5 decreased with the formation of a new product, Al-Al2O3-AlxVy, with a size range from 1.3 μm to 2.6 μm formed by the in-situ combustion reaction during sintering of HEM milled Al and V2O5 composite powders. The in-situ reaction between Al and V2O5 during the HEMM and sintering transformed the Al2O3 and AlxVy (Al3V, Al10V) phases. Most of the reduced V reacted with excess the Al to form AlxVy (Al3V, Al10V) with very little V dissolved into Al matrix. By increasing the milling time and weight percentage of V2O5, the hardness of the Al-Al2O3-AlxVy composite sintered at 1173 K increased. The composite fabricated with the HEMM Al-20wt.%V2O5 composite powder and sintering at 1173 K for 2 h had the highest hardness. 相似文献
95.
96.
Objective
Describe age-based urban pedestrian versus auto crash characteristics and identify crash characteristics associated with injury severity.Materials and methods
Secondary analysis of the 2004–2010 National Highway and Traffic Safety Administration database for Illinois. All persons in Chicago crashes with age data who were listed as pedestrians (n = 7175 child age ≤19 yo, n = 16,398 adult age ≥20 yo) were included. Incidence and crash characteristics were analyzed by age groups and year. Main outcome measures were incidence, crash setting, and injury severity. Multivariate logistic regression analysis was performed to estimate injury severity by crash characteristics.Results
Overall incidence was higher for child (146.6 per 100,000) versus adult (117.3 per 100,000) pedestrians but case fatality rate was lower (0.7% for children, 1.7% for adults). Child but not adult pedestrian injury incidence declined over time (trend test p < 0.0001 for <5 yo, 5–9 yo, and 10–14 yo; p < 0.05 for 15–19 yo, p = 0.96 for ≥20 yo). Most crashes for both children and adults took place during optimal driving conditions. Injuries were more frequent during warmer months for younger age groups compared to older (χ2p < 0.001). Midblock crashes increased as age decreased (p < 0.0001 for trend). Most crashes occurred at sites with sub-optimal traffic controls but varied by age (p < 0.0001 for trend). Crashes were more likely to be during daylight on dry roads in clear weather conditions for younger age groups compared to older (χ2p < 0.001). Daylight was associated with less severe injury (child OR 0.93, 95% CI 0.87–0.98; adult OR 0.90, 95% CI 0.87–0.93).Conclusion
The incidence of urban pedestrian crashes declined over time for child subgroups but not for adults. The setting of pedestrian crashes in Chicago today varies by age but is similar to that seen in other urban locales previously. Injuries for all age groups tend to be less severe during daylight conditions. Age-based prevention efforts may prove beneficial. 相似文献97.
98.
99.
Optoelectronics: High‐Performance Planar Perovskite Optoelectronic Devices: A Morphological and Interfacial Control by Polar Solvent Treatment (Adv. Mater. 23/2015) 下载免费PDF全文
100.
Journal of Mechanical Science and Technology - Recently, many researchers have studied to overcome some disadvantages of conventional sensing mechanisms. And the flexoelectric effect draw great... 相似文献