全文获取类型
收费全文 | 684篇 |
免费 | 24篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 131篇 |
金属工艺 | 5篇 |
机械仪表 | 17篇 |
建筑科学 | 14篇 |
矿业工程 | 3篇 |
能源动力 | 17篇 |
轻工业 | 125篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 36篇 |
一般工业技术 | 104篇 |
冶金工业 | 152篇 |
原子能技术 | 6篇 |
自动化技术 | 81篇 |
出版年
2023年 | 13篇 |
2022年 | 8篇 |
2021年 | 16篇 |
2020年 | 17篇 |
2019年 | 15篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 19篇 |
2013年 | 31篇 |
2012年 | 34篇 |
2011年 | 35篇 |
2010年 | 25篇 |
2009年 | 37篇 |
2008年 | 19篇 |
2007年 | 27篇 |
2006年 | 26篇 |
2005年 | 25篇 |
2004年 | 15篇 |
2003年 | 8篇 |
2002年 | 8篇 |
1998年 | 38篇 |
1997年 | 17篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 15篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1983年 | 10篇 |
1981年 | 8篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1974年 | 8篇 |
1973年 | 12篇 |
1971年 | 4篇 |
1970年 | 7篇 |
1969年 | 7篇 |
1968年 | 5篇 |
1967年 | 7篇 |
1966年 | 5篇 |
1963年 | 3篇 |
1961年 | 4篇 |
1960年 | 5篇 |
1958年 | 7篇 |
排序方式: 共有708条查询结果,搜索用时 15 毫秒
31.
Lysine‐241 Has a Role in Coupling 2OG Turnover with Substrate Oxidation During KDM4‐Catalysed Histone Demethylation 下载免费PDF全文
Dr. Rebecca L. Hancock Dr. Martine I. Abboud Dr. Tristan J. Smart Dr. Emily Flashman Dr. Akane Kawamura Prof. Christopher J. Schofield Dr. Richard J. Hopkinson 《Chembiochem : a European journal of chemical biology》2018,19(9):917-921
The JmjC histone lysyl demethylases (KDMs) play important roles in modulating histone methylation states and have the potential to be regulated by oxygen availability. Lys241 of the KDM4 subfamily is proposed to be important in oxygen binding by KDM4A. We report evidence that, although Lys241 is unlikely to be directly involved in oxygen binding, it has an important role in coupling 2‐oxoglutarate cosubstrate oxidation with lysine demethylase activity. The results suggest that compounds promoting the uncoupling of substrate oxidation are of interest as JmjC‐KDM inhibitors. 相似文献
32.
33.
U Schiefer M Skalej M Kolb TJ Dietrich R Kolb C Braun D Petersen 《Canadian Metallurgical Quarterly》1998,38(9):1303-1312
An attempt was made to clarify whether the site of postchiasmal lesions affects subjective perception of homonymous visual field defects during stimulation with flickering random dot patterns (white noise-field). Out of 56 patients with homonymous hemianopia, 38 (68%) perceived scotomata in this situation, but 18 (32%) discerned none at all. Neuroradiologic superposition of cerebral lesions detected by computed tomography (CT) or magnetic resonance imaging (MRI) showed that nearly all patients who perceived their scotomata had lesions involving the primary visual cortex or the perigeniculate region, whereas those who received no scotoma had lesions centered within the optic radiation. Functional MRI of six normal subjects during stimulation with flickering random dot patterns indicated predominant activation of the primary visual cortex. Since noise-field defects were most frequently perceived by patients whose lesion involved the primary visual cortex, it appears that the sensitivity of noise-field campimetry depends on the site of damage in the visual pathway. The explanation for this may be that damage to long-range horizontal connections impairs filling-in processes. 相似文献
34.
35.
36.
Herndon SC Shorter JH Zahniser MS Nelson DD Jayne J Brown RC Miake-Lye RC Waitz I Silva P Lanni T Demerjian K Kolb CE 《Environmental science & technology》2004,38(22):6078-6084
In August 2001, the Aerodyne Mobile Laboratory simultaneously measured NO, NO2, and CO2 within 350 m of a taxiway and 550 m of a runway at John F. Kennedy Airport. The meteorological conditions were such that taxi and takeoff plumes from individual aircraft were clearly resolved against background levels. NO and NO2 concentrations were measured with 1 s time resolution using a dual tunable infrared laser differential absorption spectroscopy instrument, utilizing an astigmatic multipass Herriott cell. The CO2 measurements were also obtained at 1 s time resolution using a commercial non-dispersive infrared absorption instrument. Plumes were measured from over 30 individual planes, ranging from turbo props to jumbo jets. NOx emission indices were determined by examining the correlation between NOx (NO + NO2) and CO2 during the plume measurements. Several aircraft tail numbers were unambiguously identified, allowing those specific airframe/engine combinations to be determined. The resulting NOx emission indices from positively identified in-service operating airplanes are compared with the published International Civil Aviation Organization engine certification test database collected on new engines in certification test cells. 相似文献
37.
Aerodynamic shape optimization of wind turbine blades using a Reynolds‐averaged Navier–Stokes model and an adjoint method 下载免费PDF全文
Computational fluid dynamics (CFD) is increasingly used to analyze wind turbines, and the next logical step is to develop CFD‐based optimization to enable further gains in performance and reduce model uncertainties. We present an aerodynamic shape optimization framework consisting of a Reynolds‐averaged Navier Stokes solver coupled to a numerical optimization algorithm, a geometry modeler, and a mesh perturbation algorithm. To efficiently handle the large number of design variables, we use a gradient‐based optimization technique together with an adjoint method for computing the gradients of the torque coefficient with respect to the design variables. To demonstrate the effectiveness of the proposed approach, we maximize the torque of the NREL VI wind turbine blade with respect to pitch, twist, and airfoil shape design variables while constraining the blade thickness. We present a series of optimization cases with increasing number of variables, both for a single wind speed and for multiple wind speeds. For the optimization at a single wind speed performed with respect to all the design variables (1 pitch, 11 twist, and 240 airfoil shape variables), the torque coefficient increased by 22.4% relative to the NREL VI design. For the multiple‐speed optimization, the torque increased by an average of 22.1%. Depending on the CFD mesh size and number of design variables, the optimization time ranges from 2 to 24h when using 256 cores, which means that wind turbine designers can use this process routinely. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
38.
Markus Eisele Ralf Kolb Erwin Kraus Christian von Ehrenstein 《Informatik-Spektrum》2007,30(6):407-412
Zusammenfassung Das Schlagwort NetWeaver ist seit einiger Zeit in unserer Branche en vogue. Wie so oft, ist es nicht leicht, Marketingaspekte
vom informatischen Wesensgehalt zu unterscheiden. Dieser Beitrag m?chte hier helfen. 相似文献
39.
Different routes of Cd intake may influence the intestinal distribution of Cd, metallothionein (MT), and trace metals differently. Therefore, we compared the effects of parenteral and enteral administration of Cd on the distribution of trace metals and MT along the small intestine. In a first experiment three groups of rats were employed: a control, one receiving CdCl2 within the drinking water, and another receiving sc injections of CdCl2. In a second experiment, rats were fed three different diets with either 0, 0.3, or 1 mmol CdCl2/kg for one and two weeks to study the time- and dose-dependent effects of orally administered Cd. Metal concentrations (Cd, Zn, Cu, Fe) were measured by atomic emission spectrometry and MT was determined by radioimmunoassay. Intestinal MT levels did not show proximodistal gradients in controls or after sc administration of Cd, but orally administered Cd increased mucosal MT levels longitudinally from the duodenum to the ileum. Cd levels paralleled those of MT. Compared with the metal concentrations in the controls, sc administration of Cd did not change intestinal Zn, Cu, and Fe levels. Oral administration of Cd, however, increased Cu and decreased Fe levels in the intestinal mucosa significantly. The second experiment revealed that only high dietary concentrations of Cd increase intestinal Cd and MT levels longitudinally toward the distal parts, whereas at lower dietary concentration the longitudinal distribution was reversed. This shows that different routes and doses of Cd intake lead to a different trace metal and MT distribution and emphasizes the role of dietary Cd in the local induction of small-intestinal MT. 相似文献
40.
Adiga VP Kolb PW Evans GT Cubillos-Moraga MA Schmadel DC Dyott R Drew HD 《Applied optics》2006,45(12):2597-2600
A novel, chemical-etching technique produces very high throughput, polarization-maintaining probes for near-field, scanning, optical microscopy (NSOM). The process includes coating the tips with aluminum and forming the apertures with a focused ion beam (FIB). The elliptical core fibers used resulted in elliptical apertures for the probes. The throughput of the probes depends on the incident polarization. For polarization parallel to the minor axis, the tip presents an insertion loss of only 20 dB for aperture widths of 55 nm. Probes have a typical polarization extinction of 100 to 1 in the far field. These tips produced NSOM images of gold dots on a GaAs substrate in reflection mode. 相似文献