全文获取类型
收费全文 | 74797篇 |
免费 | 710篇 |
国内免费 | 689篇 |
专业分类
电工技术 | 1428篇 |
综合类 | 47篇 |
化学工业 | 11174篇 |
金属工艺 | 3444篇 |
机械仪表 | 2637篇 |
建筑科学 | 1642篇 |
矿业工程 | 504篇 |
能源动力 | 1855篇 |
轻工业 | 6381篇 |
水利工程 | 847篇 |
石油天然气 | 2303篇 |
武器工业 | 41篇 |
无线电 | 7194篇 |
一般工业技术 | 16445篇 |
冶金工业 | 12415篇 |
原子能技术 | 2630篇 |
自动化技术 | 5209篇 |
出版年
2022年 | 574篇 |
2021年 | 903篇 |
2020年 | 695篇 |
2019年 | 777篇 |
2018年 | 1551篇 |
2017年 | 1563篇 |
2016年 | 1761篇 |
2015年 | 945篇 |
2014年 | 1556篇 |
2013年 | 3562篇 |
2012年 | 2357篇 |
2011年 | 2818篇 |
2010年 | 2371篇 |
2009年 | 2639篇 |
2008年 | 2621篇 |
2007年 | 2551篇 |
2006年 | 2186篇 |
2005年 | 1913篇 |
2004年 | 1838篇 |
2003年 | 1790篇 |
2002年 | 1704篇 |
2001年 | 1677篇 |
2000年 | 1670篇 |
1999年 | 1562篇 |
1998年 | 3671篇 |
1997年 | 2600篇 |
1996年 | 1935篇 |
1995年 | 1521篇 |
1994年 | 1325篇 |
1993年 | 1349篇 |
1992年 | 995篇 |
1991年 | 1050篇 |
1990年 | 1071篇 |
1989年 | 1050篇 |
1988年 | 940篇 |
1987年 | 874篇 |
1986年 | 878篇 |
1985年 | 936篇 |
1984年 | 777篇 |
1983年 | 766篇 |
1982年 | 676篇 |
1981年 | 689篇 |
1980年 | 661篇 |
1979年 | 646篇 |
1978年 | 620篇 |
1977年 | 773篇 |
1976年 | 931篇 |
1975年 | 580篇 |
1974年 | 552篇 |
1973年 | 544篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
O. A. Dolgopolov 《Glass and Ceramics》2005,62(5-6):155-156
Magnetic roll separators on rare-earth magnets are suitable for removing iron impurities from various materials. The advantages
of these magnetic separators over traditional ones are demonstrated.
__________
Translated from Steklo i Keramika, No. 5, p. 33, May, 2005. 相似文献
62.
O Prez‐Camacho S Sepúlveda‐Guzmn M Prez‐lvarez M García‐Zamora G Cadenas‐Pliego 《Polymer International》2005,54(12):1626-1631
New functionalized styrene–maleimide copolymers were prepared by free radical copolymerization of styrene (St) and N‐4‐carboxybutylmaleimide (NBMI) in chloroform, using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. Monomer and copolymer characterization was carried out by 1H‐ and 13C‐NMR. Copolymer composition was determined by elemental analysis and Fourier‐transform infrared (FTIR) spectroscopy. The glass transition temperature (from DSC) and the thermogravimetric analysis (TGA) of the copolymers were consistent with the thermal behavior and stability observed for alternating St–maleimide copolymers. St–NBMI copolymers crosslinked with divinylbenzene (DVB) were also synthesized and their cation exchange properties evaluated in order to assess the capacity of the new copolymers to bind metallic ions. Copyright © 2005 Society of Chemical Industry 相似文献
63.
64.
O Ukkola MJ Savolainen PI Salmela K von Dickhoff T Kiema YA Kes?niemi 《Canadian Metallurgical Quarterly》1995,73(6):307-311
In the search for new risk factors for diabetic macroangiopathy the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme gene was studied in 237 consecutive patients (125 men and 112 women) with non-insulin-dependent diabetes. The female population showed an excess of ischemic electrocardiographic changes or definite myocardial infarctions in the patients homozygous for the deletion [D/D; odds ratio (OR) 2.8; 95% confidence interval (CI) 1.4-5.3] and in the insertion/deletion heterozygotes (I/D; OR 1.8; CI 1.1-3.1) compared with the patients homozygous for the insertion (I/I). In the total series coronary heart disease, cerebrovascular disease, and claudication were more often observed in the patients with I/D (OR 1.5; CI 1.0-2.2) or the D/D genotype patients (OR 1.7; CI 1.1-2.6) than in those with the genotype I/I. The systolic blood pressure was lower in patients with genotype I/I (138 +/- 19 mmHg) than in those with the genotype I/D (149 +/- 22 mmHg) or D/D (150 +/- 21 mmHg; P < 0.02). The prevalence of hypertension and the median urinary albumin excretion rate also tended to be lowest in the I/I genotype patients. Multiple logistic analysis revealed that in women the angiotensin-converting enzyme D/D genotype is independently associated with coronary heart disease. Our findings suggest that variation at the angiotensin-converting enzyme gene locus is one of the factors involved in the predisposition of diabetic patients to the development of arterial disease and hypertension. 相似文献
65.
66.
67.
In this study, an aluminum based metallic matrix (Al-2wt.% Cu) was reinforced with SiC particulates using a conventional casting technique and a new disintegrated melt deposition technique. Microstructural characterization studies conducted on the samples taken from disintegrated melt deposition technique revealed a more uniform distribution of SiC particulates and good interfacial integrity between SiC particulates and metallic matrix when compared to the conventionally cast composite samples. Results of ambient temperature mechanical tests demonstrate an increase in 0.2% YS and ultimate tensile strength of samples taken from disintegrated melt deposition technique when compared with the unreinforced and conventionally cast composite samples. The results of microstructural characterization and mechanical testing were finally rationalized in terms of the nature of processing technique employed to reinforce Al-2wt.% Cu metallic matrix with SiC particulates. 相似文献
68.
O. N. Shablovskii 《Journal of Engineering Physics and Thermophysics》1997,70(2):319-327
A set of divergent forms of heat-transfer equations are presented. New laws are established that govern the behavior of the
temperature field behind the front of a strong discontinuity. Comparison of theoretical and experimental data on the propagation
of nonlinear waves in a sapphire crystal and liquid helium is carried out.
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 2, pp. 318–325, March–April 1997. 相似文献
69.
70.
For pt.I see IEEE Trans. Neural Networks, vol.1, p.167-78 (1990). Parallel, self-organizing, hierarchical neural networks (PSHNNs) involve a number of stages with error detection at the end of each stage, i.e., rejection of error-causing vectors, which are then fed into the next stage after a nonlinear transformation. The stages operate in parallel during testing. Statistical properties and the mechanisms of vector rejection of the PSHNN are discussed in comparison to the maximum likelihood method and the backpropagation network. The PSHNN is highly fault tolerant and robust against errors in the weight values due to the adjustment of the error detection bounds to compensate errors in the weight values. These properties are exploited to develop architectures for programmable implementations in which the programmable parts are reduced to on-off or bipolar switching operations for bulk computations and attenuators for pointwise operations 相似文献