全文获取类型
收费全文 | 2591篇 |
免费 | 34篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 166篇 |
金属工艺 | 10篇 |
机械仪表 | 17篇 |
建筑科学 | 77篇 |
矿业工程 | 1篇 |
能源动力 | 41篇 |
轻工业 | 217篇 |
水利工程 | 16篇 |
石油天然气 | 32篇 |
无线电 | 104篇 |
一般工业技术 | 159篇 |
冶金工业 | 1638篇 |
原子能技术 | 18篇 |
自动化技术 | 115篇 |
出版年
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 14篇 |
2019年 | 11篇 |
2018年 | 16篇 |
2017年 | 25篇 |
2016年 | 16篇 |
2015年 | 19篇 |
2014年 | 25篇 |
2013年 | 65篇 |
2012年 | 35篇 |
2011年 | 53篇 |
2010年 | 40篇 |
2009年 | 30篇 |
2008年 | 52篇 |
2007年 | 44篇 |
2006年 | 56篇 |
2005年 | 48篇 |
2004年 | 37篇 |
2003年 | 53篇 |
2002年 | 39篇 |
2001年 | 35篇 |
2000年 | 37篇 |
1999年 | 80篇 |
1998年 | 493篇 |
1997年 | 284篇 |
1996年 | 197篇 |
1995年 | 92篇 |
1994年 | 96篇 |
1993年 | 97篇 |
1992年 | 31篇 |
1991年 | 34篇 |
1990年 | 41篇 |
1989年 | 41篇 |
1988年 | 39篇 |
1987年 | 21篇 |
1986年 | 33篇 |
1985年 | 35篇 |
1984年 | 16篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 14篇 |
1980年 | 17篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 41篇 |
1976年 | 85篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 4篇 |
排序方式: 共有2625条查询结果,搜索用时 15 毫秒
31.
32.
Estrogenic personal care products in a greywater reuse system. 总被引:1,自引:0,他引:1
H R Andersen M Lundsbye H V Wedel E Eriksson A Ledin 《Water science and technology》2007,56(12):45-49
The occurrence and fate of parabens in a greywater system was assessed. The potential for removal of residual paraben concentrations in effluent greywater with chlorine dioxide was also investigated. The influent to the greywater plant was characterised by considerable variation, with concentrations from below the detection limit to 40 microg/L and the five commonly used parabens in consumer products were frequently detected. After the biological treatment only two paraben were detected with concentration from 65-120 ng/L. Chlorine dioxide treatment of the biologically treated effluent with dosages down to 0.75 mg/L resulted in more than 97% reduction of all parabens. Formation of the by-product chloroform was insignificant from the chlorine dioxide treatment. 相似文献
33.
34.
JN Myers 《Canadian Metallurgical Quarterly》1994,21(3):415-437
35.
36.
37.
38.
J. Clausen L. Damkilde L. Andersen 《International journal for numerical methods in engineering》2006,66(6):1036-1059
A new return method for implicit integration of linear isotropic yield criteria is presented. The basic idea is to perform all the manipulations in the principal stress space and thereby achieve very simple formulae for calculating the plastic corrector stresses, based on the constant gradient of such criteria. The return formulae are in closed form and no iteration is required. The method accounts for three types of stress return: return to a single yield plane, to a discontinuity line at the intersection of two yield planes and to a discontinuity point at the intersection between three or more yield planes. The infinitesimal and the consistent elastoplastic constitutive matrix are calculated for each type of stress return, as are the conditions to ascertain which type of return is required. The method is exemplified with the Mohr–Coulomb yield criterion. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
39.
We describe three case reports of hematomas in the abdominal wall muscles and discuss etiology, diagnostic findings and treatment. Abdominal wall hematomas are uncommon, and the condition is often misdiagnosed. One of our patients was laparotomised owing to suspected appendicitis, and one patient presented a tuberculous abscess that may have been an infected hematoma. Ultrasonographic examination or CT gives the correct diagnose. Conservative management is the treatment of choice unless bleeding is severe or the course is complicated by infection. 相似文献
40.
To check compliance with the maximum residue levels in foods and to monitor the residue levels to enable an evaluation of the exposure of the Danish population to pesticides, a monitoring programme for pesticides residues in fruit and vegetables was performed. Sampling plans were designed based on previous findings and on consumption data. Samples (n = 4404) of mainly fresh conventionally and organically grown fruit and vegetables were collected at wholesalers and importers and at food processing companies. Of the samples, 3% were frozen products and 5% organically grown. Of the samples, 34% were of Danish origin, with 66% from other countries. Two accredited laboratories performed analyses of the samples using capillary gas chromatography, liquid chromatography and a spectrophotometric method. Reporting levels were set at the lowest calibration level or at the limit of determination. Residues were found in 60% of the samples of fruit but in only 18% of the vegetable samples. Residues above the maximum residue levels were found in 6% of all samples of fruit and in 2% of the vegetable samples. 相似文献