全文获取类型
收费全文 | 405篇 |
免费 | 13篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 29篇 |
金属工艺 | 12篇 |
机械仪表 | 14篇 |
建筑科学 | 5篇 |
能源动力 | 4篇 |
轻工业 | 122篇 |
无线电 | 30篇 |
一般工业技术 | 77篇 |
冶金工业 | 51篇 |
原子能技术 | 4篇 |
自动化技术 | 68篇 |
出版年
2023年 | 5篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 27篇 |
2009年 | 17篇 |
2008年 | 16篇 |
2007年 | 15篇 |
2006年 | 16篇 |
2005年 | 12篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 10篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 9篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1941年 | 2篇 |
排序方式: 共有418条查询结果,搜索用时 265 毫秒
1.
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
2.
3.
B Pfaffenbach RJ Adamek D Hagemann S Busch K Hoffmann P Altmeyer J Schaffstein M Wegener 《Canadian Metallurgical Quarterly》1996,34(9):517-521
In patients with progressive systemic sclerosis (PSS) suffering from chronic dyspepsia the stomach may be affected by this disease. The objective of this study was to investigate both antral myoelectrical activity and gastric emptying in PSS patients. Electrogastrography (EGG) was performed in 17 PSS patients (16 female, one male, median age 58 years, range 32-74 years) with chronic dyspepsia. After an overnight fast during one hour in the fasting and one hour in the fed state after ingestion of a liquid-solid test meal (370 kcal; liquid phase labeled with 0.5 mCi 99mTc-colloid) antral electrical activity was measured by one pair of electrodes sonographically placed on the skin overlying the gastric antrum. Several EGG parameters including dominant frequency (DF), percentages of DF in the normal range (2-4 cycles per minute [cpm]), bradygastria (< 2 cpm) and tachygastria (4-10 cpm), dominant frequency instability coefficient (DFIC), and postprandial to preprandial power ratio (PR) were calculated. The data were correlated to results obtained in 20 age- and gender-matched healthy subjects. In addition, the data were compared to gastric retention of the radionuclide at 60 min measured by simultaneous scintigraphy. The PSS patients did not reveal electrical disturbances. They even exhibited a significant postprandial decrease in DFIC, bradygastria, and tachygastria (ns) compared to healthy subjects. Over 50% of the PSS patients showed a delayed gastric emptying. However, EGG did not correlate to radioscintigraphy significantly. Our results reflect an absent relationship between antral myoelectrical activity in EGG and gastric emptying. Therefore, electrogastrography is unsuitable to assess gastric involvement in PSS. 相似文献
4.
Cure of Helicobacter pylori infection: role of duration of treatment with omeprazole and amoxicillin
A case of ankylosing spondylitis with pronounced osteolysis of the 12th thoracic vertebral body as part of posttraumatic pseudoarthrosis is described. The appearance of posttraumatic osteolysis simulates a malignant lesion, and it is important to consider the diagnosis in cases of osteolytic lesions of unknown origin. 相似文献
5.
Leonard Stoloff John Dantzman John Wegener 《Journal of the American Oil Chemists' Society》1972,49(4):264-266
A procedure has been devised for preparing lot samples of mycotoxin-contaminated nut meats so that a representative analytical
sample may be removed. The sample is rapidly reduced to coarse size. A relatively large portion (about 1/10 of total sample)
of subsample is then split out and further comminuted to a fine particle size with the aid of a fat solvent (meat-solvent,
w/v, 3:2). The analytical sample is removed from this mixture. The procedure was tested with shelled almonds and shelled walnuts
using radioactive nuts to simulate the mycotoxin contamination and provide a simple, precise measure of the contaminated nut
meat distribution. The pooled coefficient of variation was 18% for the subsamples and 4.4% for the analytical samples. Considering
the dilution factors used (1.50 and 2.14 contaminated nuts/104 nuts) and the low degree of reliability of the lot sample, the sample preparation methods tested appear to be practical and
reliable. 相似文献
6.
Polyurethane prepared from tetramethylene glycol and diisocyanate was exposed in the form of films to small pressures of NO2 and to NO2 plus air. Tensile strength was measured as a function of exposure time and temperature with an apparatus especially constructed for the purpose of measuring mechanical properties in different environmental “atmospheres.” 相似文献
7.
Chemical analysis of volatiles emitted by Pinus svlvestris after induction by insect oviposition 总被引:1,自引:0,他引:1
Gas chromatography – mass spectrometry analyses of the headspace volatiles of Scots pine (Pinus sylvestris) induced by egg deposition of the sawfly Diprion pini were conducted. The odor blend of systemically oviposition-induced pine twigs, attractive for the eulophid egg parasitoid Chrysonotomyia ruforum, was compared to volatiles released by damaged pine twigs (control) that are not attractive for the parasitoid. The mechanical damage inflicted to the control twigs mimicked the damage by a sawfly female prior to egg deposition. The odor blend released by oviposition-induced pine twigs consisted of numerous mono- and sesquiterpenes, which all were also present in the headspace of the artificially damaged control twigs. A quantitative comparison of the volatiles from oviposition-induced twigs and controls revealed that only the amounts of (E)--farnesene were significantly higher in the volatile blend of the oviposition-induced twigs. Volatiles from pine twigs treated with jasmonic acid (JA) also attract the egg parasitoid. No qualitative differences were detected when comparing the composition of the headspace of JA-treated pine twigs with the volatile blend of untreated control twigs. JA-treated pine twigs released significantly higher amounts of (E)--farnesene. However, the JA treatment induced a significant increase of the amount of further terpenoid components. The release of terpenoids by pine after wounding, egg deposition, and JA treatment is discussed with special respect to (E)--farnesene. 相似文献
8.
Typical two-stage oxidation experiments in high-temperature oxidation studies on metals are analyzed. Two cases of predominant oxygen diffusion in the scale are studied: pure volume diffusion and simultaneous transport via grain boundaries and via the bulk. An analytical expression for the growth of the oxide layer is given for the assumption that the chemical potential of the oxygen varies linearly over the oxide layer. The numerical treatment of the differential equation is improved so that the calculation is possibly faster and/ or more accurate compared to a method given in the literature. The experimental profiles are described by four parameters, the grain boundary width, the grain radius, and the volume and grain boundary diffusivities. Two equations correlating these parameters can be extracted from the profiles. Two benchmark tests are described for testing the program. An analytical solution is presented which approximately describes the distribution of O-18 in the oxide layer for pure volume diffusion. Experimental SIMS profiles on Fe-Cr-Al alloys are explored on the basis of our calculation. 相似文献
9.
Mechatronic Systems for Machine Tools 总被引:3,自引:0,他引:3
This paper reviews current developments in mechatronic systems for metal cutting and forming machine tools. The integration of mechatronic modules to the machine tool and their interaction with manufacturing processes are presented. Sample mechatronic components for precision positioning and compensation of static, dynamic and thermal errors are presented as examples. The effect of modular integration of mechatronic system on the reconfigurability and reliability of the machine tools is discussed along with intervention strategies during machine tool operation. The performance and functionality aspects are discussed through active and passive intervention methods. A special emphasis was placed on active and passive damping of vibrations through piezo, magnetic and electro-hydraulic actuators. The modular integration of mechatronic components to the machine tool structure, electronic unit and CNC software system is presented. The paper concludes with the current research challenges required to expand the application of mechatronics in machine tools and manufacturing systems. 相似文献
10.