全文获取类型
收费全文 | 3177篇 |
免费 | 165篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 27篇 |
综合类 | 3篇 |
化学工业 | 805篇 |
金属工艺 | 33篇 |
机械仪表 | 19篇 |
建筑科学 | 137篇 |
矿业工程 | 5篇 |
能源动力 | 52篇 |
轻工业 | 528篇 |
水利工程 | 31篇 |
石油天然气 | 21篇 |
武器工业 | 1篇 |
无线电 | 181篇 |
一般工业技术 | 537篇 |
冶金工业 | 568篇 |
原子能技术 | 18篇 |
自动化技术 | 378篇 |
出版年
2023年 | 15篇 |
2022年 | 82篇 |
2021年 | 123篇 |
2020年 | 64篇 |
2019年 | 59篇 |
2018年 | 64篇 |
2017年 | 94篇 |
2016年 | 91篇 |
2015年 | 100篇 |
2014年 | 116篇 |
2013年 | 169篇 |
2012年 | 180篇 |
2011年 | 210篇 |
2010年 | 166篇 |
2009年 | 143篇 |
2008年 | 185篇 |
2007年 | 175篇 |
2006年 | 154篇 |
2005年 | 115篇 |
2004年 | 96篇 |
2003年 | 94篇 |
2002年 | 77篇 |
2001年 | 58篇 |
2000年 | 38篇 |
1999年 | 58篇 |
1998年 | 71篇 |
1997年 | 58篇 |
1996年 | 55篇 |
1995年 | 37篇 |
1994年 | 43篇 |
1993年 | 48篇 |
1992年 | 30篇 |
1991年 | 20篇 |
1990年 | 31篇 |
1989年 | 26篇 |
1988年 | 24篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 21篇 |
1984年 | 10篇 |
1983年 | 16篇 |
1982年 | 10篇 |
1980年 | 17篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1960年 | 5篇 |
排序方式: 共有3344条查询结果,搜索用时 0 毫秒
1.
McWayne Christine M.; Fantuzzo John W.; McDermott Paul A. 《Canadian Metallurgical Quarterly》2004,40(4):633
The present concurrent study combined developmental and ecological considerations to examine the unique contribution of multiple preschool competencies to an indicator of early academic success. Participants included 195 Head Start children from 32 classrooms representative of a large, urban Head Start program. Dimensional (variable-centered) analyses revealed 3 distinct classroom competency dimensions (i.e., General Classroom Competencies, Specific Approaches to Learning, and Interpersonal Classroom Behavioral Problems). The first 2 of these dimensions were found to be uniquely associated with early academic success. Findings from typological (person-centered) analyses supported the dimensional findings. Typological analyses revealed 7 profiles of classroom competency distinguished by high scores on the dimensions of General Competencies and Approaches to Learning, and these profiles were found to relate differentially to the indicator of early academic success. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
The effect of residual mechanical stresses on the distribution of magnetization in thin metal microwires with negative magnetostriction
has been studied in a zero magnetic field. It is established that the microwire has a nonzero residual magnetization in the
absence of twisting and bulging rotational modes. 相似文献
3.
Kreppner Jana M.; Rutter Michael; Beckett Celia; Castle Jenny; Colvert Emma; Groothues Christine; Hawkins Amanda; O'Connor Thomas G.; Stevens Suzanne; Sonuga-Barke Edmund J. S. 《Canadian Metallurgical Quarterly》2007,43(4):931
Longitudinal analyses on normal versus impaired functioning across 7 domains were conducted in children who had experienced profound institutional deprivation up to the age of 42 months and were adopted from Romania into U.K. families. Comparisons were made with noninstitutionalized children adopted from Romania and with nondeprived within-U.K. adoptees placed before the age of 6 months. Specifically, the validity of the assessment, the degree of continuity and change in levels of functioning from 6 to 11 years, and the factors in the pre- and postadoption environment accounting for heterogeneity in outcome were examined. Pervasive impairment was significantly raised in children experiencing institutional deprivation for ≥6 months of life, with a minority within this group showing no impairment. There was no additional significant effect of duration of deprivation beyond the 6-month cutoff, and few other predictors explained outcome. The pattern of normality/impairment was mainly established by 6 years of age, with considerable continuity at the individual level between 6 and 11 years. The findings are discussed in terms of the possibility of a sensitive period for development. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
5.
Cagnon Christine; Valverde Viviane; Masson Jean-Michel 《Protein engineering, design & selection : PEDS》1991,4(7):843-847
A set of 11 expression vectors was constructed, each of themharbouring a cloning cassette under the control of the promoter.Some of these vectors enable expression of foreign proteinsin the cytoplasm, while others include a synthetic sequencecoding for a very efficient secretion signal sequence. Otherfeatures are an fl origin of replication (in plus or minus orientation)and a promoterup mutation that enhances the already very highlevel of expression from these vectors. With such a versatilevector family, cloning, sequencing and sitedirected mutagenesiscan be performed on the same vector, and the level of expressioncan be defined according to the specific constraints of a givenprotein. 相似文献
6.
Christine H. Setchell 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(3):175-182
Magnetic separation technology has a broad range of potential applications in both small and large scale biotechnology. This review considers a selection of magnetic techniques and their possible uses. 相似文献
7.
Christine Di Massimo Paul A. Lant Aidan Saunders Gary A. Montague Ming T. Tham A. Julian Morris 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,53(3):265-277
The last decade has seen the development of a number of approaches for estimating those variables which are difficult to measure on-line in industrial process situations. Whilst a range of techniques is available, a common element is the use of process knowledge in the form of a system model. In the case of bioprocess systems, although a large range of models has been presented in the literature, their use in estimation schemes on an industrial scale has been limited. A number of reasons can be identified for their low level of utilisation. Of particular significance is the uncertainty which exists in quantifying system performance and the process-model mismatch which inevitably results. The level of ‘pre-defined model’ uncertainty, together with the knowledge gained during the course of the fermentation, serves to dictate estimator structure. The paper considers a range of estimation strategies and contrasts, through industrial applications, their performance characteristics and utility. 相似文献
8.
G Lipeme Kouyi J Vazquez Y Gallin D Rollet A G Sadowski 《Water science and technology》2005,51(2):187-194
A new instrumentation mode has been put in place in order to determine the overflow rate of five complex CSOs of the system in Sélestat (French), which are subject to self monitoring. 3D and 1D models have made it possible to predict the shapes of the water lines and suggest a location for the ultrasound sensors. In order to validate the instrumentation principle, three overhead sensors were placed on a weir. The overflow laws suggested are of the type Q(overflow) = a1h1b1 + a2h2b2 + a3h3b3. Early results of the overflow rate that have been obtained by applying the law are close to 10 % of the flow measured in the physical test bench. On the actual site, the ultrasound sensors were assembled on a rail covering the entire weir in order to be able to change their position in future after models calibration. 相似文献
9.
Hydroxylic and nonhydroxylic acrylates—methyl acrylate (MA), ethyl acrylate (EA), butylacrylate (BA), hydroxypropyl methacrylate (HPMA), ethylenglycol dimethacrylate (EGDMA), and mixtures of HPMA–MA, HPMA–EA, HPMA–BA in a 50/50 feed composition—were grafted onto amylopectin with different amounts of crosslinking agent, EGDMA. Percent of total conversion, percent crude grafting, and influence of pH in water content were studied. In this sense it was only at pH 10 when a real variation in the water content could be seen. It was also proved that the highest values were obtained when one of the comonomers was EGDMA with a 34 mol% of the initial feed composition. © 1994 John Wiley & Sons, Inc. 相似文献
10.
Mechanical properties and thermal stability of epoxy foams filled with white and black rice husk ash were studied. Epoxy foams were prepared from a commercial system and filled with different amounts of both the ashes (0, 6.8, 12.8, 18.0, and 22.7 wt %). The incorporation of both the ashes modified the final morphology of the foam, decreasing the average cell size and increasing the number of cells per volume unit. For all filler percentages used, the specific modulus and strength results showed that the white ash is more effective as reinforcing agent than the black ash. The initial degradation temperature was not affected by the content and type of ash used as the filler. The integral procedure decomposition temperature, weight loss, and char residue results were related to the ash type and atmosphere used in the thermogravimetric analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006 相似文献