全文获取类型
收费全文 | 121172篇 |
免费 | 2785篇 |
国内免费 | 1265篇 |
学科分类
工业技术 | 125222篇 |
出版年
2023年 | 475篇 |
2022年 | 453篇 |
2021年 | 1280篇 |
2020年 | 985篇 |
2019年 | 1167篇 |
2018年 | 1818篇 |
2017年 | 1743篇 |
2016年 | 1933篇 |
2015年 | 1517篇 |
2014年 | 2403篇 |
2013年 | 5998篇 |
2012年 | 3969篇 |
2011年 | 5550篇 |
2010年 | 4340篇 |
2009年 | 4980篇 |
2008年 | 5001篇 |
2007年 | 4911篇 |
2006年 | 4423篇 |
2005年 | 3952篇 |
2004年 | 3745篇 |
2003年 | 3529篇 |
2002年 | 3035篇 |
2001年 | 3253篇 |
2000年 | 2857篇 |
1999年 | 3287篇 |
1998年 | 9948篇 |
1997年 | 6423篇 |
1996年 | 4980篇 |
1995年 | 3385篇 |
1994年 | 2927篇 |
1993年 | 2850篇 |
1992年 | 1710篇 |
1991年 | 1674篇 |
1990年 | 1577篇 |
1989年 | 1393篇 |
1988年 | 1222篇 |
1987年 | 900篇 |
1986年 | 919篇 |
1985年 | 946篇 |
1984年 | 822篇 |
1983年 | 716篇 |
1982年 | 719篇 |
1981年 | 695篇 |
1980年 | 584篇 |
1979年 | 476篇 |
1978年 | 409篇 |
1977年 | 550篇 |
1976年 | 984篇 |
1975年 | 306篇 |
1974年 | 283篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
21.
Hend Omar Mohamed Enas Taha Sayed M. Obaid Yun-Jeong Choi Sung-Gwan Park Siham Al-Qaradawi Kyu-Jung Chae 《International Journal of Hydrogen Energy》2018,43(46):21560-21571
The poor wettability and high cost of the carbonaceous electrodes materials prohibited the practical applications of microbial fuel cells (MFCs) on large scale. Here, a novel nanoparticles of metal sheathed with metal oxide is electrodeposited on carbon paper (CP) to introduce as high-performance anodes of microbial fuel cell (MFC). This thin layer of metal/metal oxide significantly enhance the microbial adhesion, the wettability of the anode surface and decrease the electron transfer resistance. The investigation of the modified CP anodes in an air-cathode MFCs fed by various biocatalyst cultures shows a significant improving in the MFC performance. Where, the generated power and current density was 140% and 210% higher as compared to the pristine CP. Mixed culture of exoelectrogenic microorganism in wastewater exhibited good performance and generated higher power and current density compared to yeast as pure culture. The excellent capacitance with a distinctive nanostructure morphology of the modified-CP open an avenues for practical applications of MFCs. 相似文献
22.
Many studies have demonstrated the strong relationships between physiological responses and driving stress, but they have done little to build a model that could be used to identify a driver's stress accurately in real time. The objective of this study is to develop a model that accurately classifies driving stress by monitoring physiological responses—specifically galvanic skin response (GSR). GSR data were collected from nine drivers with licenses obtained in the US in real road driving situations with two stress conditions—rest period (low stress) and highway or city driving (high stress). The validation drive was performed by one driver with licenses obtained in South Korea in real long‐term road driving situations with two stress conditions—rural area (low stress) and highway or highway under construction (high stress). Those two conditions were used to build a binary logistic regression model to classify low stress or high stress based on a driver's measured hand GSR. The overall classification accuracy of the developed model was found to be 85.3%, and the accuracy of cross validation, with a testing dataset, was found to be 83.2%. A simple logit model was developed to identify drivers' stress by incorporating their GSR data. The developed model can be embedded in a wearable device equipped with GSR sensors for drivers to detect their stress level in real time. 相似文献
23.
Tekin Ramazan Ertuğrul Ömer Faruk Kaya Yılmaz 《Multimedia Tools and Applications》2020,79(43-44):32541-32561
Multimedia Tools and Applications - In this paper, four novel, simple and robust approaches, which are left to right local binary patterns (LBPLL2R), top to down local binary patterns (LBPT2D),... 相似文献
24.
Wan Huan Wang Hui Scotney Bryan Liu Jun Ng Wing W. Y. 《Multimedia Tools and Applications》2020,79(39-40):29327-29352
Multimedia Tools and Applications - In many real-world classification problems there exist multiple subclasses (or clusters) within a class; in other words, the underlying data distribution is... 相似文献
25.
Networks and Spatial Economics - This study defines the price of anarchy for general reliability-based transport network design problems, which is an indicator of inefficiency that reveals how much... 相似文献
26.
Xu Q. J. Zuo C. S. Liu D. Y. Shi W. Z. 《Theoretical Foundations of Chemical Engineering》2018,52(6):1039-1044
Theoretical Foundations of Chemical Engineering - Troxerutin supported palladium (TXT-Pd) catalyst was prepared readily by using one-step synthetic method. As-fabricated TXT-Pd catalyst was... 相似文献
27.
D.L. ALONTSEVA E. GHASSEMIEH S. VOINAROVYCH A. RUSSAKOVA O. KYSLYTSIA Y. POLOVETSKYI A. TOXANBAYEVA 《Journal of microscopy》2020,279(3):148-157
This paper presents new results of studying the influence of parameters of microplasma spraying (MPS) of Ti wire on the structure and properties of Ti coatings. Based on the design of the experiment and the results of the SEM study, certain spraying modes were chosen to form the desired composition and structure of the Ti coating. The dense sublayer (up to 300 µm thick) provides good adhesion to the substrate, and a porous top layer can accelerate the coated implant ingrowth with the bone. This technology is developed for the manufacture of coated endoprosthesis implants. 相似文献
28.
Fikret Yılmaz Semra Ergen Soon-Jik Hong Orhan Uzun 《International Journal of Hydrogen Energy》2018,43(44):20243-20251
The LaNi5 intermetallic compound is an AB5 type hydrogen storage alloy which exhibits low operating temperature, easy activation, low pressure and tolerance to impurities. In this study, LaNi4.7-x Al0.3Bix (x = 0.0, 0.1, 0.2, 0.3) alloys were produced by melt-spinning technique and the effects of Al and Bi additions on the microstructure, thermal and hydrogen storage properties of LaNi5 were investigated. The results showed that substitution of Ni with Al led to a desired decrease in absorption/desorption plateau pressure and hysteresis without a decrease in hydrogen storage capacity. In contrast, Bi substitution with Ni increased the absorption/desorption plateau pressure, reduced the hydrogen capacity and increased pulverization resistance of the alloy due to the formation of BiLa and AlNi3 intermetallic phases at the grain boundaries. 相似文献
29.
30.
Manjunatha S. Muttigi Byoung Ju Kim Bogyu Choi Inbo Han Hansoo Park Soo-Hong Lee 《International journal of molecular sciences》2020,21(23)
Adipose-derived mesenchymal stromal cells (Ad-MSCs) are a promising tool for articular cartilage repair and regeneration. However, the terminal hypertrophic differentiation of Ad-MSC-derived cartilage is a critical barrier during hyaline cartilage regeneration. In this study, we investigated the role of matrilin-3 in preventing Ad-MSC-derived chondrocyte hypertrophy in vitro and in an osteoarthritis (OA) destabilization of the medial meniscus (DMM) model. Methacrylated hyaluron (MAHA) (1%) was used to encapsulate and make scaffolds containing Ad-MSCs and matrilin-3. Subsequently, the encapsulated cells in the scaffolds were differentiated in chondrogenic medium (TGF-β, 1–14 days) and thyroid hormone hypertrophic medium (T3, 15–28 days). The presence of matrilin-3 with Ad-MSCs in the MAHA scaffold significantly increased the chondrogenic marker and decreased the hypertrophy marker mRNA and protein expression. Furthermore, matrilin-3 significantly modified the expression of TGF-β2, BMP-2, and BMP-4. Next, we prepared the OA model and transplanted Ad-MSCs primed with matrilin-3, either as a single-cell suspension or in spheroid form. Safranin-O staining and the OA score suggested that the regenerated cartilage morphology in the matrilin-3-primed Ad-MSC spheroids was similar to the positive control. Furthermore, matrilin-3-primed Ad-MSC spheroids prevented subchondral bone sclerosis in the mouse model. Here, we show that matrilin-3 plays a major role in modulating Ad-MSCs’ therapeutic effect on cartilage regeneration and hypertrophy suppression. 相似文献