全文获取类型
收费全文 | 3538篇 |
免费 | 149篇 |
专业分类
电工技术 | 26篇 |
综合类 | 1篇 |
化学工业 | 695篇 |
金属工艺 | 50篇 |
机械仪表 | 33篇 |
建筑科学 | 172篇 |
矿业工程 | 4篇 |
能源动力 | 60篇 |
轻工业 | 510篇 |
水利工程 | 42篇 |
石油天然气 | 12篇 |
无线电 | 150篇 |
一般工业技术 | 441篇 |
冶金工业 | 1152篇 |
原子能技术 | 8篇 |
自动化技术 | 331篇 |
出版年
2023年 | 23篇 |
2022年 | 59篇 |
2021年 | 113篇 |
2020年 | 60篇 |
2019年 | 69篇 |
2018年 | 90篇 |
2017年 | 75篇 |
2016年 | 99篇 |
2015年 | 55篇 |
2014年 | 97篇 |
2013年 | 208篇 |
2012年 | 165篇 |
2011年 | 231篇 |
2010年 | 173篇 |
2009年 | 177篇 |
2008年 | 184篇 |
2007年 | 181篇 |
2006年 | 149篇 |
2005年 | 146篇 |
2004年 | 95篇 |
2003年 | 93篇 |
2002年 | 104篇 |
2001年 | 68篇 |
2000年 | 68篇 |
1999年 | 66篇 |
1998年 | 54篇 |
1997年 | 51篇 |
1996年 | 68篇 |
1995年 | 47篇 |
1994年 | 54篇 |
1993年 | 49篇 |
1992年 | 43篇 |
1991年 | 17篇 |
1990年 | 37篇 |
1989年 | 38篇 |
1988年 | 36篇 |
1987年 | 28篇 |
1986年 | 30篇 |
1985年 | 28篇 |
1984年 | 30篇 |
1983年 | 22篇 |
1982年 | 22篇 |
1981年 | 23篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1978年 | 17篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1975年 | 14篇 |
1974年 | 14篇 |
排序方式: 共有3687条查询结果,搜索用时 171 毫秒
941.
Kai Zhong George Peabody Elizabeth Blankenhorn Howard Glicksman Sheryl Ehrman 《Aerosol science and technology》2013,47(2):i-v
Copyright 2013 American Association for Aerosol Research 相似文献
942.
Martin Thomas A.; Donders Jacobus; Thompson Elizabeth 《Canadian Metallurgical Quarterly》2000,45(4):402
Objective: Examination of the concurrent and criterion validities of the General Ability Measure for Adults (GAMA) and the Wechsler Adult Intelligence Scale–Third Edition (WAIS–III) in patients with traumatic brain injury (TBI). Study Design: Correlational methods and multivariate analyses of variance. Setting: Regional rehabilitation center. Participants: Prospective series of consecutive rehabilitation referrals, including 60 adults with TBI and no confounding premorbid histories. Main Outcome Measures: GAMA and WAIS–III IQ and factor index scores were obtained within 1 year after injury and were compared with each other and with measures of injury severity. Results: GAMA and WAIS–III summary IQ scores demonstrated substantial covariance (supporting concurrent validity), but neither was sufficiently sensitive to injury severity. The WAIS–III Processing Speed (PS) index was the only measure that clearly demonstrated criterion validity. Conclusions: GAMA and WAIS–III summary IQ scores measure similar abilities but may not be sensitive to degree of injury severity in individuals with TBI. In contrast, the WAIS–III PS index appears to have promise in the evaluation of sequelae of TBI. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
943.
The Potts Monte Carlo simulation was used to simulate microstructural evolution in uranium dioxide fuel rods. During service, grain growth, pore migration, and thermal segregation of the pores and UO2 occur in the rods in a thermal gradient. In this investigation, we developed a model which simulates simultaneous grain growth, pore migration, and thermal segregation of the pores and UO2 in a temperature gradient. Grain growth in a thermal gradient was simulated using the Monte Carlo Potts model technique developed by Anderson, Srolovitz, and co-workers. Pore migration was simulated using conserved dynamics with minimum-energy exchanges at a finite temperature. A temperature gradient was introduced into the model via interfacial mobility gradient. Finally, thermal segregation of the pores and UO2 was achieved by introducing a heat of migration term, Δ E t , which biased the motion of porosity to the high-temperature region. The development of this model is described and the incorporation of the proper physics of pore migration and thermal segregation is discussed. 相似文献
944.
Complex cognitive skills such as reading and calculation and complex cognitive achievements such as formal science and mathematics may depend on a set of building block systems that emerge early in human ontogeny and phylogeny. These core knowledge systems show characteristic limits of domain and task specificity: Each serves to represent a particular class of entities for a particular set of purposes. By combining representations from these systems, however human cognition may achieve extraordinary flexibility. Studies of cognition in human infants and in nonhuman primates therefore may contribute to understanding unique features of human knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
945.
Smith Jared G.; Harris John P.; Khan Saleem; Atkinson Elizabeth A.; Fowler M. Susan; Gregory Ralph P. 《Canadian Metallurgical Quarterly》2010,24(4):443
Objective: To relate lateralized impairments of visual perception in Parkinson's disease to asymmetries in the severity of motor symptoms. Method: Ten patients with worse left-sided motor symptoms (LPD), 15 with worse right-sided (RPD), and 13 healthy age-matched controls (all right-handed) viewed mirror-imaged pairs of emotional chimeric faces, (left side smiling, right neutral, and vice versa), of greyscales (strips whose luminance varied smoothly from black on the left to white on the right, and vice versa) and of gender chimeric faces (left side male, right female, and vice versa). Participants signaled which stimulus appeared happier, brighter, or more feminine, respectively, so showing which side received more attention. Results: For emotional chimeras, controls and LPD showed little bias, whereas RPD showed a strong bias to left hemispace (p = .018, r = .45). Across all patients, this bias was associated with severity of right-sided motor impairment (p = .018, r = .49). The bias was much weaker and insignificant for greyscales (p = .72, r = .14). For gender chimeras, RPD again showed a significantly greater left hemispace bias than did LPD (p = .037, r = .47), although neither patient group differed significantly from controls. Across all patients, this bias correlated with ratio of right-to-left symptom severity (p = .044, r = .48). Conclusions: The left hemispace bias in RPD is greater for facial than for luminance judgments, and is amplified for emotional judgments. Asymmetrical degeneration of the striatum, particularly involving the left side, appears to underlie this deficit in visual processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
946.
Tallman Benjamin; Shaw Kari; Schultz Jessica; Altmaier Elizabeth 《Canadian Metallurgical Quarterly》2010,55(2):204
Objective: To study posttraumatic growth and psychological and physical well-being among 25 cancer survivors (12 men, 13 women) 9 years after receiving a hematopoietic stem cell transplant from an unrelated donor. Measures: Participants completed measures of well-being (e.g., depression, physical function) and posttraumatic growth at the 9-year follow-up. Prior to treatment, optimism, social support, and well-being had been assessed. Results: Findings reveal high levels of physical and psychological well-being. Survivors reported posttraumatic growth in several domains, including increased personal strengths and enhanced interpersonal relationships. Higher levels of growth were significantly related to gender and age: Women reported more total posttraumatic growth, and older survivors reported more enhanced spirituality, one domain of growth. Posttraumatic growth and well-being after treatment were predicted by 2 psychosocial variables assessed prior to treatment: dispositional optimism and social support. Implications: Although long-term survivors report ongoing physical limitations, they also experience well-being in both physical and psychological domains. Posttraumatic growth is an area of well-being deserving of additional research and clinical attention. In particular, there may be reason to assist survivors to articulate growth as part of ongoing care. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
947.
It is widely recognised that flood disturbance has important consequences for the biodiversity of riparian zones and that inundation allows nutrients and organic matter to be exchanged and recycled between aquatic and terrestrial ecosystems. Previous research has focused on the impacts of dams on riparian biodiversity, with little consideration given to the impacts of flood defences. The current study investigated the extent to which the presence and age of flood defences controls riparian plant richness and abundance. Sites without flood defences were found to have significantly higher species richness and abundance. In contrast, flood defence age was found to have little impact although turnover was high between sites with old and new defences. Flood management should therefore focus on more sustainable options that work with natural processes where possible, such as washlands. 相似文献
948.
Objective: The ability to imagine an elaborative event from a personal perspective relies on several cognitive processes that may potentially enhance subsequent memory for the event, including visual imagery, semantic elaboration, emotional processing, and self-referential processing. In an effort to find a novel strategy for enhancing memory in memory-impaired individuals with neurological damage, we investigated the mnemonic benefit of a method we refer to as self-imagining—the imagining of an event from a realistic, personal perspective. Method: Fourteen individuals with neurologically based memory deficits and 14 healthy control participants intentionally encoded neutral and emotional sentences under three instructions: structural-baseline processing, semantic processing, and self-imagining. Results: Findings revealed a robust “self-imagination effect (SIE),” as self-imagination enhanced recognition memory relative to deep semantic elaboration in both memory-impaired individuals, F(1, 13) = 32.11, p 相似文献
949.
Sadeh Naomi; Javdani Shabnam; Jackson Joshua J.; Reynolds Elizabeth K.; Potenza Marc N.; Gelernter Joel; Lejuez C. W.; Verona Edelyn 《Canadian Metallurgical Quarterly》2010,119(3):604
Although prior research has examined the genetic correlates of antisocial behavior, molecular genetics influences on psychopathic traits remain largely unknown. Consequently, we investigated the influence of polymorphic variation at the serotonin transporter protein gene (SLC6A4) and socioeconomic resources (SES) on psychopathic traits in youth across two distinct samples in two separate studies. In Study 1, a main effect of serotonin transporter (5-HTTLPR) genotype was associated with the impulsivity dimension of psychopathy. That is, individuals homozygous for the short allele evidenced more impulsivity than did those homozygous for the long allele. In contrast, a gene–environment interaction was associated with the callous-unemotional and narcissistic features of psychopathy. Callous-unemotional and narcissistic traits increased as SES decreased only among youths with the homozygous-long (l/l) genotype, a novel finding replicated and extended in Study 2. These studies provide preliminary results that the l/l genotype confers risk for the emotional deficits and predatory interpersonal traits associated with psychopathy among youths raised in disadvantaged environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
950.
Jose-Alberto Gallegos-Infante Luis Arturo Bello-Perez Nuria Elizabeth Rocha-Guzman Ruben Francisco Gonzalez-Laredo Martha Avila-Ontiveros 《Journal of food science》2010,75(5):H151-H156
Abstract: Spaghetti is considered to be a slowly digestible starch food, a feature ruled by the particular physical properties of the product. Several studies have been reported to increase nutritional value of spaghetti, using legumes. We have studied the addition of common bean flour on the starch in vitro digestibility. Spaghetti was prepared with semolina and different concentrations of common bean flour (0%, 15%, 30%, and 45%, w/w). Proximate analysis, optimal cooking time, and cooking loss were estimated in crude spaghetti. Total, available, and resistant starches, indigestible fractions, and in vitro starch hydrolysis kinetics were accomplished in cooked spaghetti. Pasta with 30% and 45% of common bean flour showed higher values of protein. Particularly, the lowest cooking time was observed for composite spaghetti with 45% of common bean flour. There was a significant increase in cooking loss when common bean flour in the composite was added. Composite spaghetti samples with increasing common bean flour showed decreasing values of total starch but an important increase in the resistant starch (RS) level and indigestible insoluble fraction values. Plain pasta made with semolina showed the highest enzymatic hydrolysis rate, which decreased when common bean flour was added to the spaghetti. Spaghetti with a higher level of common bean flour was more slowly available, which may have positive implications for human health. 相似文献