全文获取类型
收费全文 | 294542篇 |
免费 | 8379篇 |
国内免费 | 3025篇 |
专业分类
电工技术 | 6792篇 |
技术理论 | 2篇 |
综合类 | 2700篇 |
化学工业 | 44591篇 |
金属工艺 | 10757篇 |
机械仪表 | 10172篇 |
建筑科学 | 9794篇 |
矿业工程 | 1835篇 |
能源动力 | 8488篇 |
轻工业 | 31439篇 |
水利工程 | 2762篇 |
石油天然气 | 4313篇 |
武器工业 | 342篇 |
无线电 | 38628篇 |
一般工业技术 | 51886篇 |
冶金工业 | 48853篇 |
原子能技术 | 3844篇 |
自动化技术 | 28748篇 |
出版年
2022年 | 2533篇 |
2021年 | 3939篇 |
2020年 | 2911篇 |
2019年 | 3115篇 |
2018年 | 4060篇 |
2017年 | 4119篇 |
2016年 | 4305篇 |
2015年 | 4037篇 |
2014年 | 5883篇 |
2013年 | 14596篇 |
2012年 | 9471篇 |
2011年 | 12749篇 |
2010年 | 9886篇 |
2009年 | 10787篇 |
2008年 | 11322篇 |
2007年 | 11062篇 |
2006年 | 10520篇 |
2005年 | 9283篇 |
2004年 | 8509篇 |
2003年 | 8261篇 |
2002年 | 7693篇 |
2001年 | 7970篇 |
2000年 | 7254篇 |
1999年 | 7798篇 |
1998年 | 17176篇 |
1997年 | 12054篇 |
1996年 | 9189篇 |
1995年 | 7061篇 |
1994年 | 6100篇 |
1993年 | 5836篇 |
1992年 | 4215篇 |
1991年 | 3967篇 |
1990年 | 3708篇 |
1989年 | 3516篇 |
1988年 | 3373篇 |
1987年 | 2672篇 |
1986年 | 2538篇 |
1985年 | 3205篇 |
1984年 | 2831篇 |
1983年 | 2594篇 |
1982年 | 2369篇 |
1981年 | 2407篇 |
1980年 | 2226篇 |
1979年 | 2058篇 |
1978年 | 1886篇 |
1977年 | 2183篇 |
1976年 | 2741篇 |
1975年 | 1593篇 |
1974年 | 1495篇 |
1973年 | 1568篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Dr. Qian Wang Xinli Fan Nannan Jing Han Zhao Dr. Lijia Yu Prof. Xinjing Tang 《Chembiochem : a European journal of chemical biology》2021,22(11):1901-1907
Small interfering RNA (siRNA) can effectively silence target genes through Argonate 2 (Ago2)-induced RNA interference (RNAi). It is very important to control siRNA activity in both spatial and temporal modes. Among different masking strategies, photocaging can be used to regulate gene expression through light irradiation with spatiotemporal and dose-dependent resolution. Many different caging strategies and caging groups have been reported for light-activated siRNA gene silencing. Herein, we describe a novel caging strategy that increases the blocking effect of RISC complex formation/process through host/guest (including ligand/receptor) interactions, thereby enhancing the inhibition of caged siRNA activity until light activation. This strategy can be used as a general approach to design caged siRNAs for the photomodulation of gene silencing of exogenous and endogenous genes. 相似文献
22.
Romero-Garcés A. Salles De Freitas R. Marfil R. Vicente-Chicote C. Martínez J. Inglés-Romero J. F. Bandera A. 《Multimedia Tools and Applications》2022,81(3):3603-3628
Multimedia Tools and Applications - The design of robots capable of operating autonomously in changing and unstructured environments, requires using complex software architectures in which,... 相似文献
23.
Kedong Xia Shuoshuo Yu Yunling Li Huijuan Han Lingyao Duan Zhenyu Hou Xiao Liu 《Journal of the European Ceramic Society》2021,41(4):2375-2385
In this study, C/SiOC and C/SiO2 composites were prepared by using carbonaceous microspheres with different surface functional groups. Carbonaceous microspheres based on hydrothermal reaction of glucose contains hydroxyl group, while the surface carboxyl group increases after NaOH etching. The hydroxyl group increases the oxygen-enriched structural units of SiOC ceramics, and the C spheres are closely enwrapped in SiOC matrix after pyrolysis at 900 °C. However, the interfacial reaction of surface carboxyl with Si–OH results in the formation of cristobalite SiO2, and C spheres are not only encased inside the SiOC matrix, but also dispersed outside of SiOC ceramics. After removal of C via calcination at 500 °C for 5 h, C/SiOC and C/SiO2 composites are transformed into amorphous SiO2 and cristobalite SiO2, respectively. The thermogravimetric analysis indicates the oxidation resistance of SiOC is superior to that of C and SiO2. 相似文献
24.
Belcher Calvin H. Zheng Baolong MacDonald Benjamin E. Langlois Eric D. Lehman Benjamin Pearce Charles Delaney Robert Apelian Diran Lavernia Enrique J. Monson Todd C. 《Journal of Materials Science》2022,57(9):5518-5532
Journal of Materials Science - For transformers and inductors to meet the world’s growing demand for electrical power, more efficient soft magnetic materials with high saturation magnetic... 相似文献
25.
Carolyn A. Grimley Stephen Funni Christopher Green Elizabeth C. Dickey 《Journal of the European Ceramic Society》2021,41(4):2807-2817
In flash sintering experiments, the thermal history of the sample is key to understanding the mechanisms underlying densification rate and final properties. By combining robust temperature measurements with current-ramp-rate control, this study examined the effects of the thermal profile on the flash sintering of yttria-stabilized zirconia, with experiments ranging from a few seconds to several hours. The final density was maximized at slower heating rates, although processes slower than a certain threshold led to grain growth. The amount of grain growth observed was comparable to a similar conventional thermal process. The bulk electrical conductivity correlated with the maximum temperature and cooling rate. The only property that exhibited behavior that could not be attributed to solely the thermal profile was the grain boundary conductivity, which was consistently higher than conventional in flash sintered samples. These results suggest that, during flash sintering, athermal electric field effects are relegated to the grain boundary. 相似文献
26.
Wenjie Liu Jianmin Liu Shu Xing Xiaobin Li Liwen Han Kechun Liu Tao Wei Mingyang Zhou 《European Journal of Lipid Science and Technology》2021,123(6):2000276
In this study, the anti-atherosclerotic properties of three marine phospholipids (MPLs) extracts from fishery by-products including codfish roe, squid gonad, and shrimp head are verified. Their effects on key factors involved in atherosclerosis are examined and compared to explore whether the differences in their constitutions lead to the differences in the function. All three MPLs dampen oxidation of low- density lipoproteins (LDL) in vitro. Treating RAW264.7 macrophages and HUVECs endothelial cells with each MPLs ranging 10–100 µg mL−1 does not decrease cell viability, yet ox-LDL caused cytotoxicity of both cells are alleviated by 50 or 100 µg mL−1 MPLs treatment. In addition, the three MPLs reduce ox-LDL induced macrophage foam-like transition, mainly through inhibition of lipid uptake. Of the three MPLs, the one from squid gonad exhibits the best effect. On the other hand, all three MPLs modulate inflammatory responses, equally, by inhibiting the adhesion of monocytes to endothelial cells, and decreasing secretion of pro-inflammatory cytokines IL-6 and MCP-1. Using a high-cholesterol diet induced zebrafish model, it is found that all three MPLs, especially the one from squid gonad, alleviates cholesterol accumulation in early plaques, and decreases total cholesterol as well as lipid peroxide in vivo. Practical Applications: As a way of making the best of the increasingly scarce marine resources, valuable lipid components can be recovered from by-products and wastes from the fishery industry. Here, we tested the anti-atherosclerotic effects and the mechanisms of three MPLs extracted from codfish roe, squid gonad, and shrimp head. Our study provides further evidence that marine phospholipids extracted from fishery by-products could protect against atherosclerosis, and helps to elucidate the structure-function relationship of MPLs. 相似文献
27.
28.
Tuladhar Sanira Alsadoon Abeer Prasad P. W. C. Ali Akbas Ezaldeen Alrubaie Ahmad 《Multimedia Tools and Applications》2022,81(17):23845-23865
Multimedia Tools and Applications - Gastrointestinal stromal tumor is one of the critical tumors that doctors do not suggest to get frequent endoscopy, so there is a need for a diagnosis system... 相似文献
29.
30.
Amino acid modified polyaspartic acids were evaluated as calcium-scale inhibitors. Feasibility of scale inhibition experiments was analyzed by molecular dynamics simulation and Gaussian optimization, and the scale inhibition mechanism was theoretically analyzed. Scale inhibition performance was studied by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, static scale inhibition experiments, and electrochemical performance testing, which provided an experimental basis for the molecular dynamics simulation. The experimental results showed that Arg-SA-PASP has better scale inhibition and corrosion inhibition performance than His-SA-PASP. The scale inhibition effect increased with increasing concentration. Electrochemical tests indicated that Arg-SA-PASP is an excellent scale and corrosion inhibitor. 相似文献