全文获取类型
收费全文 | 12748篇 |
免费 | 737篇 |
国内免费 | 41篇 |
专业分类
电工技术 | 171篇 |
综合类 | 15篇 |
化学工业 | 2679篇 |
金属工艺 | 449篇 |
机械仪表 | 939篇 |
建筑科学 | 230篇 |
矿业工程 | 3篇 |
能源动力 | 438篇 |
轻工业 | 1099篇 |
水利工程 | 83篇 |
石油天然气 | 13篇 |
无线电 | 2347篇 |
一般工业技术 | 2744篇 |
冶金工业 | 707篇 |
原子能技术 | 167篇 |
自动化技术 | 1442篇 |
出版年
2024年 | 13篇 |
2023年 | 163篇 |
2022年 | 231篇 |
2021年 | 438篇 |
2020年 | 282篇 |
2019年 | 326篇 |
2018年 | 367篇 |
2017年 | 420篇 |
2016年 | 457篇 |
2015年 | 379篇 |
2014年 | 554篇 |
2013年 | 825篇 |
2012年 | 833篇 |
2011年 | 1015篇 |
2010年 | 734篇 |
2009年 | 781篇 |
2008年 | 722篇 |
2007年 | 569篇 |
2006年 | 494篇 |
2005年 | 446篇 |
2004年 | 413篇 |
2003年 | 368篇 |
2002年 | 383篇 |
2001年 | 292篇 |
2000年 | 261篇 |
1999年 | 244篇 |
1998年 | 363篇 |
1997年 | 237篇 |
1996年 | 179篇 |
1995年 | 123篇 |
1994年 | 111篇 |
1993年 | 91篇 |
1992年 | 65篇 |
1991年 | 56篇 |
1990年 | 50篇 |
1989年 | 57篇 |
1988年 | 30篇 |
1987年 | 39篇 |
1986年 | 18篇 |
1985年 | 30篇 |
1984年 | 16篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
Woohyeon Shin Jun Seop Kim Heesung Kim Hui Ju Choi Hee Jung Lee Moon Kwang Um Moon Kee Choi Kyeongwoon Chung 《大分子材料与工程》2021,306(5):2100007
Hydrogels are recognized as one of the most promising materials for e-skin devices because of their unique applicable functionalities such as flexibility, stretchability, biocompatibility, and conductivity. Beyond the excellent sensing functionalities, the e-skin devices further need to secure a target-oriented 3D structure to be applied onto various body parts having complex 3D shapes. However, most e-skin devices are still fabricated in simple 2D film-type devices, and it is an intriguing issue to fabricate complex 3D e-skin devices resembling target body parts via 3D printing. Here, a material design guideline is provided to prepare multifunctional hydrogels and their target-oriented 3D structures based on extrusion-based 3D printing. The material design parameters to realize target-oriented 3D structures via 3D printing are systematically derived from the correlation between material design of hydrogels and their gelation characteristics, rheological properties, and 3D printing processability for extrusion-based 3D printing. Based on the suggested material design window, ion conductive self-healable hydrogels are designed and successfully applied to extrusion-based 3D printing to realize various 3D shapes. 相似文献
922.
The effect of galactomannans (guar gum and locust bean gum) at different concentrations (0, 0.2, 0.4 and 0.6%, w/w) on rheological properties of sweet potato starch (SPS) was studied. The flow behaviors of SPS‐galactomannan mixtures were determined from the rheological parameters of power law and Casson models. The SPS‐galactomannan mixtures had high shear‐thinning fluid characteristics (n = 0.30‐0.36) exhibiting yield stress at 25°C. The presence of galactomannans resulted in the increase in consistency index (K), apparent viscosity (ηa,100) and Casson yield stress (σoc). In the temperature range of 25‐70°C, the mixtures followed the Arrhenius temperature relationship. Dynamic rheological tests at 25°C indicated that the SPS‐galactomannan mixtures had weak gel‐like behavior with storage moduli (G′) higher than loss moduli (G") over most of the frequency range (0.63‐62.8 rad/s) with frequency dependency. The magnitudes of dynamic moduli (G′, G" and η*) of the SPS‐galactomannan mixtures were higher than those of the control (0% gum), and increased with an increase in gum concentration. The tan δ (ratio of G"/G′) values (0.41‐0.46) of SPS‐guar gum mixtures were much lower than those (0.50‐0.63) of SPS‐locust bean gum mixtures, indicating that there was a more pronounced effect of guar gum on the elastic properties of SPS. 相似文献
923.
Seung-Hwan Lee Seung-Chang Kim Han-Ha Chai Soo-Hyun Cho Hyeong-Cheol Kim Dajeong Lim Bong-Hwan Choi Chang-Gwan Dang Aditi Sharma Cedric Gondro Boh-Suk Yang Seong-Koo Hong 《Meat science》2014
The objective of this study was to evaluate the effects of seven single nucleotide polymorphisms (SNPs) in Calpain 1 and Calpastatin genes previously associated with meat tenderness attributes in other cattle breeds in Korean Hanwoo cattle. The Hanwoo resource population was used to study association of 7 SNPs with beef tenderness, flavor, juiciness, intramuscular fat and shear force. In this association study, CAST:c.182A > G (+ 0.14, P = 0.04) and CAST:c.1985G > C (− 0.12, P = 0.02) had significant effects on juiciness, but no effects on other traits. In contrast, CAPN1:c.1589G > A was associated with meat tenderness (P = 0.01) and juiciness (P = 0.04). The CAPN1:c.1589G > A (Val530Ile) SNP marker displayed significant effect on the meat tenderness score which is strongly supported by molecular modeling of the CAPN1:c.1589G > A (Val530Ile) variant that inhibits CAST protein from binding more strongly than the wild-type protein, which may explain its effect on meat tenderness. 相似文献
924.
Choe JH Jang A Lee ES Choi JH Choi YS Han DJ Kim HY Lee MA Shim SY Kim CJ 《Meat science》2011,87(1):12-18
This study aimed to evaluate the oxidative and color stability of cooked ground pork containing lotus leaf powder at 0.1 (LP1) and 0.5% (LP2) as well as barley leaf powder at 0.1 (BP1) and 0.5% (BP2) during refrigerated storage for 10 days. The oxidative stability of these powders was compared with butylhydroxytoluene (BHT). LP1 had higher a* and lower b* values than the control (-) over 4 days (p<0.05). The pH values of the ground pork samples made with addition of LP and BHT decreased until day 4 and then increased. Thiobarbituric acid-reactive substance (TBARS) values were lowest in LP2 on day 10 (p<0.05). The ground pork samples containing LP and BP had lower peroxide values (POVs) and conjugated dienes (CD) compared to the control (-).These results indicate that LP or BP can be incorporated into ground pork to effectively retard oxidation after cooking. 相似文献
925.
926.
Numerical simulation technology was applied for optimizing the casting design and conditions in large cast iron castings for marine engine. By the simulation of mold filling and solidification sequences the problems of the previous casting conditions were analyzed and marked improvements for large cylinder liner parts were derived from these results. Especially the amount and positions of chills were optimized to increase the mechanical properties and to minimize the shrinkage and microporosity in the castings. Ultrasonic testing, penetration testing and mechanical property testing were carried out for the parts with the modified casting conditions. It showed that no defects in the castings were found and the productivity could be distinctly increased. The mechanical properties satisfied also the specification demanded. 相似文献
927.
Comparative study of Al2O3, HfO2, and HfAlOx for improved self‐compliance bipolar resistive switching 下载免费PDF全文
Andrey S. Sokolov Seok Ki Son Donghwan Lim Hoon Hee Han Yu‐Rim Jeon Jae Ho Lee Changhwan Choi 《Journal of the American Ceramic Society》2017,100(12):5638-5648
The comparison of resistive switching (RS) storage in the same device architecture is explored for atomic layer deposition (ALD) Al2O3, HfO2 and HfAlOx‐based resistive random access memory (ReRAM) devices. Among them, the deeper high‐ and low‐ resistance states, more uniform VSET‐VRES, persistent ROFF/RON (>102) ratio and endurance up to 105 cycles during both DC and AC measurements were observed for HfAlOx‐based device. This improved behavior is attributed to the intermixing of amorphous Al2O3/HfO2 oxide layers to form amorphous thermally stable HfAlOx thin films by consecutive‐cycled ALD. In addition, the higher oxygen content at Ti/HfAlOx thin films interface was found within the energy dispersive spectroscopy analysis (EDS). We believe this higher oxygen content at the interface could lead to its sufficient storage and supply, leading to the stable filament reduction‐oxidation operation. Further given insight to the RS mechanism, SET/RESET power necessities and scavenging effect shed a light to the enhancement of HfAlOx‐based ReRAM device as well. 相似文献
928.
929.
930.
Supercritical carbon dioxide (SC-CO2) extractions (with and without ethanol as an entrainer) were carried out to remove lipids and pigments from protein concentrate of green algae (Scenedesmus obliquus) cultivated under controlled conditions. The content and fatty acid composition of algal lipids using column, thin-layer (TLC) and gas-liquid chromatography (GLC) were determined. Absorption spectra of extracted fractions showed the predominance of chlorophyll A (lambda max at 410 nm). Single step supercritical carbon dioxide (SC-CO2) extraction resulted mostly in removal of neutral lipids and a part of glycolipids, but phospholipids were not extracted. Addition of ethanol to SC-CO2 increased the amount of glycolipids and phospholipids in the extract. TLC pattern of algal lipids showed that the main part of neutral lipids consisted of diglycerides, triglycerides, hydrocarbons, free sterols, and sterol esters. The glycolipids were mostly monogalactosyl diglyceride, digalactosyl diglyceride, esterified sterol glycoside, and sterol glycoside. In phospholipids, phosphatidyl choline, phosphatidyl glycerol, and phosphatidyl ethanolamine were the main compounds. Fatty acid composition patterns indicated the main fatty acids to be 16:0, 16:1, 16:2, 16:3, 16:4, 18:1, 18:2, and 18:3(a). Relatively high recovery of polyunsaturated fatty acids and essential fatty acids in supercritical fluid extracted algal lipids and proteins isolates were observed. 相似文献