全文获取类型
收费全文 | 36054篇 |
免费 | 2545篇 |
国内免费 | 1399篇 |
专业分类
电工技术 | 1686篇 |
综合类 | 2144篇 |
化学工业 | 6343篇 |
金属工艺 | 1758篇 |
机械仪表 | 2159篇 |
建筑科学 | 3214篇 |
矿业工程 | 702篇 |
能源动力 | 1095篇 |
轻工业 | 2242篇 |
水利工程 | 545篇 |
石油天然气 | 2018篇 |
武器工业 | 238篇 |
无线电 | 4341篇 |
一般工业技术 | 4651篇 |
冶金工业 | 1885篇 |
原子能技术 | 460篇 |
自动化技术 | 4517篇 |
出版年
2024年 | 158篇 |
2023年 | 533篇 |
2022年 | 914篇 |
2021年 | 1279篇 |
2020年 | 967篇 |
2019年 | 788篇 |
2018年 | 870篇 |
2017年 | 1034篇 |
2016年 | 953篇 |
2015年 | 1203篇 |
2014年 | 1556篇 |
2013年 | 1988篇 |
2012年 | 2084篇 |
2011年 | 2271篇 |
2010年 | 1892篇 |
2009年 | 1896篇 |
2008年 | 1880篇 |
2007年 | 1836篇 |
2006年 | 1901篇 |
2005年 | 1688篇 |
2004年 | 1169篇 |
2003年 | 1053篇 |
2002年 | 1053篇 |
2001年 | 887篇 |
2000年 | 989篇 |
1999年 | 1066篇 |
1998年 | 1021篇 |
1997年 | 832篇 |
1996年 | 834篇 |
1995年 | 696篇 |
1994年 | 555篇 |
1993年 | 493篇 |
1992年 | 335篇 |
1991年 | 255篇 |
1990年 | 256篇 |
1989年 | 172篇 |
1988年 | 150篇 |
1987年 | 101篇 |
1986年 | 82篇 |
1985年 | 59篇 |
1984年 | 51篇 |
1983年 | 36篇 |
1982年 | 33篇 |
1981年 | 23篇 |
1980年 | 20篇 |
1979年 | 10篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1973年 | 8篇 |
1970年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
142.
Six new 1,3,4-thiadiazole Schiff base derivatives were synthesized and characterized by IR spectroscopy and ~1H NMR spectrometry, and their anti-corrosion properties and thermal stability were investigated via thermogravimetric analysis(TGA) and copper strip corrosion test. The tribological behavior of the said Schiff base derivatives was evaluated on an Optimol SRV~?4 oscillating reciprocating friction and wear tester. The worn surfaces of the steel discs were investigated using a scanning electron microscope(SEM) and energy dispersive X-ray spectrometer(EDS). The test results indicated that these thiadiazole Schiff base derivatives possessed favourable thermal stability, corrosion inhibiting ability and the capability of improving the tribological characteristic of the base oil effectively. It is assumed that the adsorbed additives probably reacted with the steel surfaces during the friction process, resulting in the formation of a protective film composed of sulphates, sulphides and organic nitrogen compounds. 相似文献
143.
144.
沈海军 《计算机与应用化学》2007,24(6):819-822
采用分子动力学(MD)方法,模拟了Cn(n=60,180,240,540),以及C60@C240富勒烯在水中的速度衰减过程,得到了它们的阻力-速度与阻力-雷诺(Re)数关系曲线;进而将MD模拟的阻力结果和低Re数宏观流体力学中球的Stokes阻力解进行了对比。研究表明,低Re数下,富勒烯在水中的阻力要比传统流体力学中球的Stoke解高两个数量级;富勒烯在水中的阻力可通过Stokes解乘以(110.38-1.48/Re)近似估算。 相似文献
145.
K. Zhang W.P. Shen C.C. Ge 《金属学报(英文版)》2007,20(1):59-64
W / Cu functionally gradient materials (FGMs) containing 1%La_2O_3 and 1%TiC were prepared using graded sintering under ultra-high pressure (GSUHP). The specimens have been found to exhibit low porosity (11.57% and 11.35%, respectively). Shearing strength of the specimens between layers is good. Moreover, the specimens have still demonstrated good performance in testing thermal-shock resistance. When power density of laser is 200MWm~(-2), the specimens have been tested for thermal-shock resistance (1000 times); the specimens that contained 1%La_2O_3 were not subjected to damage, whereas those that contained 1%TiC began to crack. Finally, effect of additives on thermal-shock resistance was also preliminarily discussed. 相似文献
146.
Xueyin Mei Xingyu Li Chen Zhao Anna Liu Yan Ding Chuanlai Shen Jian Li 《International journal of molecular sciences》2022,23(9)
Chronic hepatitis B virus (HBV), a potentially life-threatening liver disease, makes people vulnerable to serious diseases such as cancer. T lymphocytes play a crucial role in clearing HBV virus, while the pathway depends on the strong binding of T cell epitope peptide and HLA. However, the experimental identification of HLA-restricted HBV antigenic peptides is extremely time-consuming. In this study, we provide a novel prediction strategy based on structure to assess the affinity between the HBV antigenic peptide and HLA molecule. We used residue scanning, peptide docking and molecular dynamics methods to obtain the molecular docking model of HBV peptide and HLA, and then adopted the MM-GBSA method to calculate the binding affinity of the HBV peptide–HLA complex. Overall, we collected 59 structures of HLA-A from Protein Data Bank, and finally obtained 352 numerical affinity results to figure out the optimal bind choice between the HLA-A molecules and 45 HBV T cell epitope peptides. The results were highly consistent with the qualitative affinity level determined by the competitive peptide binding assay, which confirmed that our affinity prediction process based on an HLA structure is accurate and also proved that the homologous modeling strategy for HLA-A molecules in this study was reliable. Hence, our work highlights an effective way by which to predict and screen for HLA-peptide binding that would improve the treatment of HBV infection. 相似文献
147.
研究和分析了高辐射GaAlAs/GaAs LED的退化机理。经高温加速老化,估算器件的工作寿命为10~5小时,并估算该器件的激活能为0.58eV。 相似文献
148.
Chengli Wang Zhiwei Fang Ailun Yi Bingcheng Yang Zhe Wang Liping Zhou Chen Shen Yifan Zhu Yuan Zhou Rui Bao Zhongxu Li Yang Chen Kai Huang Jiaxiang Zhang Ya Cheng Xin Ou 《光:科学与应用(英文版)》2021,(8):1474-1484
The realization of high-quality (Q) resonators regardless of the underpinning material platforms has been a ceaseless pursuit, because the high-Q resonators pro... 相似文献
149.
Chunxia Qiao Ming Lv Xinying Li Xiaoling Lang Shouqin Lv Mian Long Yan Li Shusheng Geng Zhou Lin Beifen Shen Jiannan Feng 《工程(英文)》2021,7(11):1566-1576
Fully human antibodies have minimal immunogenicity and safety profiles. At present, most potential antibody drugs in clinical trials are humanized or fully human. Human antibodies are mostly generated using the phage display method (in vitro) or by transgenic mice (in vivo); other methods include B lymphocyte immortalization, human–human hybridoma, and single-cell polymerase chain reaction. Here, we describe a structure-based computer-aided de novo design technology for human antibody generation. Based on the complex structure of human epidermal growth factor receptor 2 (HER2)/Herceptin, we first designed six short peptides targeting the potential epitope of HER2 recognized by Herceptin. Next, these peptides were set as complementarity determining regions in a suitable immunoglobulin frame, giving birth to a novel anti-HER2 antibody named “HF,” which possessed higher affinity and more effective anti-tumor activity than Herceptin. Our work offers a useful tool for the quick design and selection of novel human antibodies for basic mechanical research as well as for imaging and clinical applications in immune-related diseases, such as cancer and infectious diseases. 相似文献
150.