全文获取类型
收费全文 | 3819篇 |
免费 | 6篇 |
专业分类
电工技术 | 26篇 |
综合类 | 3篇 |
化学工业 | 114篇 |
金属工艺 | 13篇 |
机械仪表 | 14篇 |
建筑科学 | 26篇 |
能源动力 | 17篇 |
轻工业 | 34篇 |
水利工程 | 3篇 |
石油天然气 | 8篇 |
无线电 | 102篇 |
一般工业技术 | 125篇 |
冶金工业 | 3255篇 |
原子能技术 | 5篇 |
自动化技术 | 80篇 |
出版年
2016年 | 14篇 |
2015年 | 8篇 |
2014年 | 16篇 |
2013年 | 40篇 |
2012年 | 29篇 |
2011年 | 24篇 |
2010年 | 20篇 |
2009年 | 12篇 |
2008年 | 28篇 |
2007年 | 18篇 |
2006年 | 19篇 |
2005年 | 20篇 |
2004年 | 23篇 |
2003年 | 26篇 |
2002年 | 28篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 105篇 |
1998年 | 874篇 |
1997年 | 470篇 |
1996年 | 309篇 |
1995年 | 203篇 |
1994年 | 143篇 |
1993年 | 216篇 |
1992年 | 43篇 |
1991年 | 51篇 |
1990年 | 52篇 |
1989年 | 61篇 |
1988年 | 52篇 |
1987年 | 61篇 |
1986年 | 60篇 |
1985年 | 58篇 |
1984年 | 9篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 39篇 |
1980年 | 42篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 110篇 |
1976年 | 256篇 |
1975年 | 22篇 |
1973年 | 9篇 |
1972年 | 8篇 |
1971年 | 7篇 |
1969年 | 7篇 |
1964年 | 9篇 |
1963年 | 8篇 |
1933年 | 9篇 |
1928年 | 11篇 |
排序方式: 共有3825条查询结果,搜索用时 281 毫秒
1.
RE Vlietstra 《Canadian Metallurgical Quarterly》1993,16(10):2073-2074
2.
BF Habbick JL Nanson RE Snyder RE Casey AL Schulman 《Canadian Metallurgical Quarterly》1996,87(3):204-207
Ethers and thioethers of monosaccharides have been synthesised which show potent toxicity to mouse (LD50 > or = 4 g.kg-1 O.W. and 0.2 to 1.5 g.kg-1 I.P.W.). A study of calcium antagonist activity for the full series of compounds indicated that the activity was similar for both O- and S- ethers and maximum activities were observed for monoacetoneglucose ethers possessing carbon chain close to 8 carbons. 相似文献
3.
BACKGROUND: IgE-mediated hypersensitivity to latex proteins has become a significant clinical problem over the last decade. Nursing and medical staff are at risk because of their occupational exposure to latex. AIMS: To determine the prevalence of type I hypersensitivity to latex allergens in the nursing staff of an Australian hospital. METHODS: A questionnaire which asked about symptoms associated with the use of latex gloves was completed by 140 nurses working in the Alfred Hospital (72 in general medical wards, 68 in intensive care units). Skin prick tests with eluates of five different types of latex glove as well as common aeroallergens (rye pollen and house dust mite) and banana extract were performed. RESULTS: Thirty-one nurses (22%) were skin prick test positive to at least one of the five latex glove eluates. All of these nurses were atopic, having positive skin prick tests to rye pollen or house dust mite. Symptoms of local dryness, itch and erythema associated with glove use were reported by more than half the study group, but not more frequently by those who were skin prick test positive to latex. Urticaria associated with glove use was reported more frequently by those with positive latex skin prick tests (13% vs 4%, p = 0.05). Eighty-seven per cent of the nurses who were latex skin test positive were also positive to banana extract. CONCLUSIONS: IgE-mediated hypersensitivity to latex is common in nurses working in an Australian hospital. Glove associated symptoms were frequently reported, but in most cases the symptoms were more typical of irritant or contact dermatitis rather than type I hypersensitivity reactions. However, the extent of subclinical sensitisation to latex found in this study suggests that symptomatic latex allergy is likely to emerge as an increasing problem for nursing staff in this country. 相似文献
4.
5.
RE O'Carroll A Moffoot KP Ebmeier C Murray GM Goodwin 《Canadian Metallurgical Quarterly》1993,23(2):341-347
Eighteen patients suffering from Alcoholic Korsakoff's Syndrome participated in a placebo-controlled double-blind cross-over trial of clonidine 0.3 mg b.d. for two weeks versus matched placebo for two weeks. A detailed neuropsychological assessment was carried out at the end of each treatment phase and staff ratings of behaviour were also obtained. Clonidine treatment resulted in no significant improvement over placebo on any of the cognitive measures employed. The results contradict previous smaller studies which had suggested that chronic treatment with clonidine had a memory-enhancing effect in Korsakoff's syndrome. 相似文献
6.
The phenotypic characteristics of three Serpulina pilosicoli strains isolated from humans with diarrhoea (WesB, Kar, Hrm7) and two porcine S. pilosicoli strains isolated from pigs with intestinal spirochaetosis (1648, 3295), were compared with the type strain of the species P43/6/78T (T = type strain) and other intestinal spirochaetes within the genus Serpulina. All S. pilosicoli strains had a characteristic ultrastructural appearance, displayed similar growth rates, hydrolysed hippurate, lacked beta-glucosidase activity, utilised D-ribose as a growth substrate, and had similar sensitivities to rifampicin and spiramycin. The only consistent phenotypic characteristic that differentiated human strains from porcine strains of S. pilosicoli was that the human strains all utilised the pentose sugar D-xylose. These distinguishing phenotypic traits appear useful for identifying S. pilosicoli. 相似文献
7.
8.
Ron Kimmel Doron Shaked Michael Elad Irwin Sobel 《IEEE transactions on image processing》2005,14(6):796-803
Gamut mapping deals with the need to adjust a color image to fit into the constrained color gamut of a given rendering medium. A typical use for this tool is the reproduction of a color image prior to its printing, such that it exploits best the given printer/medium color gamut, namely the colors the printer can produce on the given medium. Most of the classical gamut mapping methods involve a pixel-by-pixel mapping and ignore the spatial color configuration. Recently proposed spatial-dependent approaches for gamut mapping are either based on heuristic assumptions or involve a high computational cost. In this paper, we present a new variational approach for space-dependent gamut mapping. Our treatment starts with the presentation of a new measure for the problem, closely related to a recent measure proposed for Retinex. We also link our method to recent measures that attempt to couple spectral and spatial perceptual measures. It is shown that the gamut mapping problem leads to a quadratic programming formulation, guaranteed to have a unique solution if the gamut of the target device is convex. An efficient numerical solution is proposed with promising results. 相似文献
9.
Uwe Kruger David Antory Juergen Hahn George W. Irwin Geoff McCullough 《Computers & Chemical Engineering》2005,29(11-12):2355
Although principal component analysis (PCA) is an important tool in standard multivariate data analysis, little interest has been devoted to assessing whether the underlying relationship within a given variable set can be described by a linear PCA model or whether nonlinear PCA must be utilized. This paper addresses this deficiency by introducing a nonlinearity measure for principal component models. The measure is based on the following two principles: (i) the range of recorded process operation is divided into smaller regions; and (ii) accuracy bounds are determined for the sum of the discarded eigenvalues. If this sum is within the accuracy bounds for each region, the process is assumed to be linear and vice versa. This procedure is automated through the use of cross-validation. Finally, the paper shows the utility of the new nonlinearity measure using two simulation studies and with data from an industrial melter process. 相似文献
10.
A new chromosome encoding method, named fuzzy coding, is proposed for representing real number parameters in a genetic algorithm. Fuzzy coding provides the value of a parameter on the basis of the optimum number of selected fuzzy sets and their effectiveness in terms of degree of membership. Thus, it represents the knowledge associated with each parameter and is an indirect method of encoding compared with alternatives, where the parameters are directly represented in the encoding. Fuzzy coding is described and compared with conventional binary coding, gray coding, and floating-point coding. Two test examples, along with neural identification of a nonlinear pH process from experimental data, are studied. It is shown that fuzzy coding is better than the conventional methods and is effective for parameter optimization in problems where the search space is complicated. 相似文献