全文获取类型
收费全文 | 484篇 |
免费 | 3篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 69篇 |
金属工艺 | 3篇 |
机械仪表 | 13篇 |
建筑科学 | 10篇 |
能源动力 | 16篇 |
轻工业 | 16篇 |
无线电 | 26篇 |
一般工业技术 | 106篇 |
冶金工业 | 152篇 |
原子能技术 | 8篇 |
自动化技术 | 65篇 |
出版年
2021年 | 3篇 |
2019年 | 3篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 13篇 |
2012年 | 11篇 |
2011年 | 15篇 |
2010年 | 16篇 |
2009年 | 13篇 |
2008年 | 7篇 |
2007年 | 14篇 |
2006年 | 14篇 |
2005年 | 18篇 |
2004年 | 12篇 |
2003年 | 17篇 |
2002年 | 15篇 |
2001年 | 14篇 |
2000年 | 13篇 |
1999年 | 13篇 |
1998年 | 45篇 |
1997年 | 27篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1976年 | 14篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有487条查询结果,搜索用时 0 毫秒
1.
2.
Corticotropin-releasing factor (CRF) has previously been shown to selectively dilate the mesenteric vascular bed, without affecting other vascular beds. Pancreatic blood flow and islet blood flow were therefore measured separately with a microsphere technique in the two regions of the rat pancreas perfused by the superior mesenteric artery (SMA) or celiac artery (CA) respectively. Intravenous infusion of CRF (0.25 microgram/kg b.w./min) caused an increase in both whole pancreatic blood flow and islet blood flow in the region of the pancreas perfused by the SMA. The fraction of whole pancreatic blood flow diverted through the islets in this part of the pancreas was, however, unaffected by CRF infusion (approximately 10%). CRF did not change either pancreatic or islet blood flow in the CA-perfused part of the pancreas, and did not affect the release of insulin. 相似文献
3.
The thermal stress on building‐integrated photovoltaic modules (BIPV) in Espoo, Finland, was studied with field‐testing of amorphous silicon modules. Based on these results, the thermal stress at two other European locations (Paris and Lisbon) was estimated. The estimation procedure entailed thermal modelling of heat transfer in the façade with meteorological data as input. The results indicate that the thermal stress on BIPV modules in Lisbon is, in this case, approximately 50% higher that in Espoo and between 80 and 200% higher than in Paris, depending on the activation energy of the degradation process. The difference in stress between a BIPV module and a free‐standing module in Espoo was 50–200%. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
4.
5.
M Tondel G Carlsson L Hardell M Eriksson S Jakobsson U Flodin A Sk?ldestig O Axelson 《Canadian Metallurgical Quarterly》1996,71(6):947-950
An experiment was conducted to elucidate the origin of tetraploids (2n = 4x = 44) of Paragonimus westermani that occur together with diploid (2n = 2x = 22) and triploid (2n = 3x = 33) types in Liaoning Province, the People's Republic of China. Metacercariae of the diploid type, obtained from Hyogo Prefecture, Japan, and those of the triploid type from Tsushima, Nagasaki Prefecture, Japan, were mixed and inoculated into dogs and cats. The following results were obtained. The flukes were found in pairs within cysts in random combinations of 2x + 2x, 2x + 3x, and 3x + 3x (7:15:7). Oocytes in the oviduct were at stages from diplotene to metaphase. In a triploid fluke encysted with a diploid fluke, the primary oocytes were intruded by sperms from the diploid fluke. In the primary oocytes of diploid as well as triploid flukes, from diplotene to diakinesis, the homologues of the nucleolar chromosomes were heteromorphic as far as the size of the short arm was concerned. This implies that the triploid is an autotriploid generated in an ancestral diploid population that was polymorphic for the nucleolar chromosome. 相似文献
6.
Proton pencil beams in water, in a format suitable for treatment planning algorithms and covering the radiotherapy energy range (50-250 MeV), have been calculated using a modified version of the Monte Carlo code PTRAN. A simple analytical model has also been developed for calculating proton broad-beam dose distributions which is in excellent agreement with the Monte Carlo calculations. Radial dose distributions are also calculated analytically and narrow proton pencil-beam dose distributions derived. The physical approximations in the Monte Carlo code and in the analytical model together with their limitations are discussed. Examples showing the use of the calculated set of proton pencil beams as input to an existing photon treatment planning algorithm based on biological optimization are given for fully 3D scanned proton pencil beams; these include intensity modulated beams with range shift and scanning in the transversal plane. 相似文献
7.
The degradation of interlaminar shear strength and shear fracture toughness of glass/epoxy composites due to uptake of distilled water and sea water has been studied. The composites were immersed in water for up to eight months at temperatures up to 70 °C. Unreinforced matrix resin samples were also immersed for periods up to 2 years. Sea water was absorbed less rapidly than distilled water. Weight gains below 1% did not influence the shear strength while higher weight gains reduced shear strength up to 25%. The loss in apparent interlaminar shear strength was uniquely related to specimen weight gain. Mode II fracture toughness, G
IIc, also decreased with increasing immersion time after an initial incubation period, but the accelerated tests were found to reduce G
IIc less than the room temperature tests at comparable weight gains. 相似文献
8.
9.
Decision making with a fuzzy ontology 总被引:2,自引:2,他引:0
Christer Carlsson Matteo Brunelli József Mezei 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2012,16(7):1143-1152
Knowledge mobilisation is a transition from the prevailing knowledge management technology that has been widely used in industry for the last 20?years to a new methodology and some innovative methods for knowledge representation, formation and development and for knowledge retrieval and distribution. Knowledge mobilisation aims at coming to terms with some of the problems of knowledge management and at the same time to introduce new theory, new methods and new technology. More precisely, this paper presents an outline of a fuzzy ontology as an enhanced version of classical ontology and demonstrates some advantages for practical decision making. We show that a number of soft computing techniques, e.g. aggregation functions and interval valued fuzzy numbers, will support effective and practical decision making on the basis of the fuzzy ontology. We demonstrate the knowledge mobilisation methods with the construction of a support system for finding the best available wine for a number of wine drinking occasions using a fuzzy wine ontology and fuzzy reasoning methods; the support system has been implemented for a Nokia N900 smart phone. 相似文献
10.
Leif A. Carlsson Carl -Gustaf Aronsson Jan Bäcklund 《Journal of Materials Science》1989,24(5):1670-1682
Inplane tensile fracture of unnotched and notched thermoset graphite-epoxy and thermoplastic graphite-PEEK composite laminates is examined. Both fibre-dominated quasi-isotropic and matrix dominated ±45 angle-ply layups were investigated.Classical lamination theory predictions of elastic and strength properties of unnotched specimens are compared with experiments. Several notched geometries, i.e. centre-notched, double-edge notched and open-hole specimens subjected to tensile loading to fracture were examined. The notched strength of the quasi-isotropic laminates was analysed by a damage zone model, where damage around the notch is represented by an equivalent crack with cohesive force acting between the crack surfaces.Good agreement between experimental and calculated strength was observed for the graphite-epoxy laminates which failed in a collinear manner. For the graphite-PEEK laminates discrepancies between predicted and experimental strength are related to observed deviations from collinear crack growth. The angle-ply graphite-PEEK laminates showed larger notch sensitivity than the corresponding graphite-epoxy, probably due to less degree of stress relieving damage formation around the notch. 相似文献