全文获取类型
收费全文 | 612篇 |
免费 | 48篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 16篇 |
综合类 | 17篇 |
化学工业 | 101篇 |
金属工艺 | 24篇 |
机械仪表 | 29篇 |
建筑科学 | 31篇 |
矿业工程 | 24篇 |
能源动力 | 8篇 |
轻工业 | 45篇 |
水利工程 | 12篇 |
石油天然气 | 14篇 |
无线电 | 81篇 |
一般工业技术 | 77篇 |
冶金工业 | 127篇 |
原子能技术 | 5篇 |
自动化技术 | 56篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 15篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 6篇 |
2014年 | 19篇 |
2013年 | 29篇 |
2012年 | 14篇 |
2011年 | 19篇 |
2010年 | 20篇 |
2009年 | 25篇 |
2008年 | 23篇 |
2007年 | 33篇 |
2006年 | 23篇 |
2005年 | 24篇 |
2004年 | 20篇 |
2003年 | 21篇 |
2002年 | 19篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 24篇 |
1998年 | 26篇 |
1997年 | 34篇 |
1996年 | 26篇 |
1995年 | 12篇 |
1994年 | 17篇 |
1993年 | 15篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有667条查询结果,搜索用时 15 毫秒
51.
52.
53.
Ryan G. McClarren D. RyuR. Paul Drake Michael GrosskopfDerek Bingham Chuan-Chih ChouBruce Fryxell Bart van der HolstJames Paul Holloway Carolyn C. KuranzBani Mallick Erica RutterBen R. Torralva 《Reliability Engineering & System Safety》2011,96(9):1194-1207
This work discusses the uncertainty quantification aspect of quantification of margin and uncertainty (QMU) in the context of two linked computer codes. Specifically, we present a physics based reduction technique to deal with functional data from the first code and then develop an emulator for this reduced data. Our particular application deals with conditions created by laser deposition in a radiating shock experiment modeled using the Lagrangian, radiation-hydrodynamics code Hyades. Our goal is to construct an emulator and perform a sensitivity analysis of the functional output from Hyades to be used as an initial condition for a three-dimensional code that will compute the evolution of the radiating shock at later times. Initial attempts at purely statistical data reduction techniques, were not successful at reducing the number of parameters required to describe the Hyades output. We decided on an alternate approach using physical arguments to decide what features/locations of the output were relevant (e.g., the location of the shock front or the location of the maximum pressure) and then used a piecewise linear fit between these locations. This reduced the number of outputs needed from the emulator to 40, down from the O(1000) points in the Hyades output. Then, using Bayesian MARS and Gaussian process regression, we were able to build emulators for Hyades and study sensitivities to input parameters. 相似文献
54.
以宁夏平罗县为研究对象,将Unispec-SC 便携式光谱仪测得的盐渍化光谱数据和实验室测得的土壤含盐量数据作为基础数据源。运用高光谱数据处理方法,分析不同盐渍化地区植被的光谱特征曲线;对实测植被、土壤光谱曲线进行对数、均方根和一阶微分等变换,筛选与土壤含盐量相关性最好的变换形式和特征波段构造盐分指数SI 及多种植被指数,利用多元非线性回归分析建立土壤盐渍化遥感监测模型。结果表明:土壤、植被光谱一阶微分变换与土壤含盐量响应敏感;协同盐分指数SI 和植被指数MSAVI 构造的土壤盐渍化指数模型,模拟值和实测值相关系数达到0.758 9,模拟效果很好,实现快速提取该区域的土壤盐渍化信息。 相似文献
55.
Ohmic contacts to n-GaN using Ag, Au, TiN, Au/Ti, Au/Mo/Ti, and Au/Si/Ti have been studied. The Fermi level of GaN appears
to be unpinned, and metals and compounds with work functions less than the electron affinity resulted in ohmic contacts. Reactively
sputter deposited TiN was ohmic as deposited. However, Au/Ti, Au/Mo/Ti, and Au/Si/Ti required heat treatments to form ohmic
contacts, with the best being an RTA at 900°C. Ag and Au were shown to diffuse across the GaN surface at T>500°C; therefore,
they are unstable, poor ohmic contact metallizations as single metals. The other contact schemes were thermally stable up
to 500°C for times of 30 min. 相似文献
56.
57.
Previous studies developed a model to predict theoretically the low-frequency plane-wave reflection coefficient of an array of pyramid cone absorbers such as those used to line anechoic electromagnetic measurement chambers. The present authors apply this model in a geometrical optics approach to predict the electromagnetic field in a chamber lined with cone absorbers in the frequency range of 30-300 MHz. The results are compared with site attenuation measurements for two actual semi-anechoic chambers 相似文献
58.
Responds to comments by B. D. Forman (see record 1990-29006-001), S. A. Kirschner (see record 1990-29011-001), and M. Rohrbaugh (see record 1990-29019-001) on the present authors' (see record 1990-29009-001) work on the use of paradoxical interventions with couples. Focus is on (1) the subjectivist and objectivist research approach; (2) language, relationship, and content analysis; and (3) the relevancy of science to practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
59.
M Schindler S Holloway PP Humphrey H Waldvogel RL Faull W Berger PC Emson 《Canadian Metallurgical Quarterly》1998,9(3):521-525
AIMS: To quantify birth prevalence and spectrum of congenital heart disease in the Island population of Malta, and compare these rates with previous studies. METHODS: All patients diagnosed as having congenital heart disease by echocardiography, cardiac catheterization, surgery or post-mortem by 1 year of age between 1990-1994 were included. There were 231 cases of live born congenital heart disease with a birth prevalence of 8.8/1000 live births. The commonest lesions were ventricular septal defect, pulmonary stenosis and tetralogy of Fallot. The rates of individual lesions were compared with two recent epidemiological studies with similar methodologies. RESULTS: Although the overall birth prevalence of congenital heart disease was similar in three studies, significantly higher rates of pulmonary stenosis, tetralogy of Fallot and double outlet right ventricle were found in Malta, all of which predispose to right ventricular outflow tract obstruction. In contrast, there were lower rates of lesions causing left ventricular outflow tract obstruction. A higher rate of ventricular septal defect was also found. The Maltese gene pool may contain an inherent predisposition towards lesions causing right ventricular outflow tract obstruction. 相似文献
60.