全文获取类型
收费全文 | 4090篇 |
免费 | 100篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 34篇 |
综合类 | 7篇 |
化学工业 | 1185篇 |
金属工艺 | 116篇 |
机械仪表 | 63篇 |
建筑科学 | 224篇 |
矿业工程 | 9篇 |
能源动力 | 85篇 |
轻工业 | 826篇 |
水利工程 | 16篇 |
石油天然气 | 8篇 |
武器工业 | 4篇 |
无线电 | 177篇 |
一般工业技术 | 473篇 |
冶金工业 | 440篇 |
原子能技术 | 47篇 |
自动化技术 | 478篇 |
出版年
2021年 | 70篇 |
2020年 | 42篇 |
2019年 | 43篇 |
2018年 | 51篇 |
2017年 | 35篇 |
2016年 | 80篇 |
2015年 | 67篇 |
2014年 | 71篇 |
2013年 | 153篇 |
2012年 | 111篇 |
2011年 | 160篇 |
2010年 | 132篇 |
2009年 | 141篇 |
2008年 | 136篇 |
2007年 | 107篇 |
2006年 | 109篇 |
2005年 | 105篇 |
2004年 | 93篇 |
2003年 | 79篇 |
2002年 | 82篇 |
2001年 | 64篇 |
2000年 | 73篇 |
1999年 | 96篇 |
1998年 | 153篇 |
1997年 | 121篇 |
1996年 | 92篇 |
1995年 | 85篇 |
1994年 | 59篇 |
1993年 | 50篇 |
1992年 | 54篇 |
1991年 | 54篇 |
1990年 | 48篇 |
1989年 | 60篇 |
1988年 | 40篇 |
1987年 | 49篇 |
1986年 | 43篇 |
1985年 | 50篇 |
1984年 | 45篇 |
1983年 | 39篇 |
1981年 | 40篇 |
1980年 | 35篇 |
1977年 | 37篇 |
1976年 | 37篇 |
1917年 | 84篇 |
1916年 | 45篇 |
1915年 | 43篇 |
1914年 | 39篇 |
1913年 | 68篇 |
1912年 | 115篇 |
1910年 | 31篇 |
排序方式: 共有4192条查询结果,搜索用时 265 毫秒
11.
12.
G Berding H Schliephake G Neumann R Schmelzeisen FW Neukam GJ Meyer KF Gratz H Hundeshagen 《Canadian Metallurgical Quarterly》1996,35(5):156-163
AIM: The aim of this study was early differentiation between uncomplicated and complicated processes of healing in the jaw using bone SPECT. METHODS: Investigations were performed in 40 mandibular fractures and 26 jaws after onlay osteoplasty as well as secondary insertion of implants. Bone SPECT was carried out within 1-2 months and after approximately 4-5 months. The uptake in the jaw was assessed semi-quantitatively using ROI analysis. RESULTS: Fractures with uncomplicated healing showed a decrease of uptake in follow-up, whereas fractures with an infection in the later course showed an increase, resulting in a significantly higher uptake at the follow-up investigation for the latter group. 1-2 months after onlay osteoplasty significantly lower uptake was found in regions with later occurrence of sequestration. In regions with implants in which osseointegration failed, there was significant reduction of uptake initially and significant elevation at the follow-up investigation. CONCLUSION: These results indicate a prognostic relevance of bone SPECT in the evaluation of processes of healing in the jaw. 相似文献
13.
用多种快重离子辐照高定向石墨(HOPG),借助扫描隧道显微镜(STM)系统地研究了表面及体内缺陷,结果表明,离子在表面及解理面上都形成了小丘状的缺陷,且在表面较容易形成,可以用非连续损伤径迹结构来对其进行解释。 相似文献
14.
15.
New measurements of the vapor-phase viscosity of phenol were performed from 437 up to 624 K and for densities between 0.006 and 0.023 mol · L–1 in an all-quartz oscillating-disk viscometer with small gaps. Thus, including our own measurements reported earlier, experimental data are available in the temperature range between 376 and 639 K and in the density range from 0.001 up to 0.023 mol · L–1. The data were evaluated with a density series for the viscosity in which only a linear density contribution is included. The values of the second viscosity virial coefficient obtained for phenol as well as for benzene, toluene, and p-xylene were compared with results of the Rainwater-Friend theory and of the modified Enskog theory on the basis of the Lennard-Jones 12-6 potential. The agreement is reasonable, when the potential parameter ratios determined by Bich and Vogel are used. The influence of bound dimers seems to be already taken into account in the three-monomer contribution according to Hoffman and Curtiss.Paper dedicated to Professor Joseph Kestin. 相似文献
16.
17.
18.
Manfred Edelhäuser und Karl-Gustav Bergner 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1987,184(3):189-194
Zusammenfassung Die Isolierung der Saccharase (E.C. 3.2.1.20) aus den Proteinkonzentraten von Raps-, Tannen- und Zuckerfütterungshonig wird beschrieben. Die Abtrennung von anderen Enzymen, insbesondere von saurer Phosphatase gelingt durch hydrophobe Wechselwirkungschromatographie, von inerten Proteinen durch Gelfiltration. Im Zusammenhang damit wird das Verhalten des Enzyms bei der Chromatographie an Anionenaustauschern, an Hydroxylapatit und an immobilisiertem Weizenkeimlectin untersucht. Dabei ergab sich am Lectin-Gel eine Trennung in zwei multiple Formen.Die Saccharase aus allen drei Honigsorten verhielt sich einheitlich, woraus zu schließen ist, daß sie ausschließlich von der Biene stammt. Ihre Molekül masse wurde gelchromatographisch zu 57000 ermittelt.
The proteins of honeyVIII. Honey sucrase, isolation, chromatographic behaviour and properties
Summary The isolation of the honey sucrase (E.C. 3.2.1.20) from rape- and fir-honey as well as from honey obtained after sugar feeding is described. The separation from other honey enzymes especially from acid phosphatase succeded by reversed phase chromatography. Separation of other, non-active proteins was accomplished by gel permeation chromatography. The behaviour of the honey sucrase upon chromatography on anion exchangers, on hydroxylapatite and wheat germ lectin was investigated. No differences were found between the sucrases of the three honeys.The molecular weight was determined at 57 000. By affinity chromatography with wheat germ lectin the enzyme could be separated into two multiple forms.相似文献
19.
Many real-world problems are multi-objective optimization problems and evolutionary algorithms are quite successful on such problems. Since the task is to compute or approximate the Pareto front, multi-objective optimization problems are considered as more difficult than single-objective problems. One should not forget that the fitness vector with respect to more than one objective contains more information that in principle can direct the search of evolutionary algorithms. Therefore, it is possible that a single-objective problem can be solved more efficiently via a generalized multi-objective model of the problem. That this is indeed the case is proved by investigating the computation of minimum spanning trees.This work was supported by the Deutsche Forschungsgemeinschaft (DFG) as part of the Collaborative Research Center Computational Intelligence (SFB 531) and by the German-Israeli Foundation (GIF) in the project Robustness Aspects of Algorithms. 相似文献
20.