全文获取类型
收费全文 | 4497篇 |
免费 | 195篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 23篇 |
综合类 | 8篇 |
化学工业 | 1206篇 |
金属工艺 | 48篇 |
机械仪表 | 50篇 |
建筑科学 | 188篇 |
矿业工程 | 13篇 |
能源动力 | 68篇 |
轻工业 | 731篇 |
水利工程 | 27篇 |
石油天然气 | 9篇 |
无线电 | 127篇 |
一般工业技术 | 519篇 |
冶金工业 | 1120篇 |
原子能技术 | 26篇 |
自动化技术 | 534篇 |
出版年
2023年 | 27篇 |
2022年 | 191篇 |
2021年 | 206篇 |
2020年 | 82篇 |
2019年 | 99篇 |
2018年 | 111篇 |
2017年 | 85篇 |
2016年 | 103篇 |
2015年 | 98篇 |
2014年 | 139篇 |
2013年 | 263篇 |
2012年 | 178篇 |
2011年 | 229篇 |
2010年 | 190篇 |
2009年 | 159篇 |
2008年 | 219篇 |
2007年 | 196篇 |
2006年 | 149篇 |
2005年 | 136篇 |
2004年 | 122篇 |
2003年 | 98篇 |
2002年 | 126篇 |
2001年 | 74篇 |
2000年 | 68篇 |
1999年 | 87篇 |
1998年 | 94篇 |
1997年 | 60篇 |
1996年 | 77篇 |
1995年 | 51篇 |
1994年 | 57篇 |
1993年 | 57篇 |
1992年 | 61篇 |
1990年 | 50篇 |
1989年 | 69篇 |
1988年 | 46篇 |
1987年 | 52篇 |
1986年 | 56篇 |
1985年 | 55篇 |
1984年 | 58篇 |
1983年 | 45篇 |
1982年 | 30篇 |
1981年 | 47篇 |
1980年 | 28篇 |
1979年 | 25篇 |
1978年 | 24篇 |
1977年 | 25篇 |
1976年 | 31篇 |
1975年 | 27篇 |
1973年 | 17篇 |
1970年 | 18篇 |
排序方式: 共有4697条查询结果,搜索用时 15 毫秒
11.
Interviewed 120 sunbathing and nonsunbathing beachgoers about their health practices, knowledge about skin cancer, moods, and social rewards obtained through sunbathing. Ss also completed personality questionnaires. Data were considered using a theoretical perspective combining aspects of health belief, social influence, social learning, and risk-taking models. Results indicate that sunbathing was related to having a positive attitude toward risk taking, having little knowledge about skin cancer, reporting a relaxed mood, having friends who sunbathe, and engaging in activities related to maintaining a positive physical appearance. Sunscreen use was related to sex, having knowledge about skin cancer, knowing people who have had cancer, and reporting high levels of anxiety. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
X. Biquard O. Proux J. Cibert D. Ferrand H. Mariette R. Giraud B. Barbara 《Journal of Superconductivity and Novel Magnetism》2003,16(1):127-129
Mn has been incorporated in epilayers of the large-gap semiconductor GaN grown by molecular beam epitaxy using a nitrogen plasma cell. Detailed extended X-ray absorption fine structure (EXAFS) studies of a Ga0.98Mn0.02N epilayer confirm that the Mn atoms substitute the Ga atoms, with an increase by 2.7% of the distance to the nearest nitrogen atoms. Near-edge spectroscopy results tend to indicate that the valence state of Mn is slightly higher than 3+, while EXAFS analysis suggests an electron transfer to the N neighbors. 相似文献
13.
Thompson Robert J.; Gil Karen M.; Burbach Daniel J.; Keith Barbara R.; Kinney Thomas R. 《Canadian Metallurgical Quarterly》1993,61(3):468
In this study, 64% of children aged 7–12 yrs with sickle cell disease were found to have a parent-reported behavior problem, and 50% met the criteria for a Diagnostic and Statistical Manual of Mental Disorders-III-Revised (DSM-III-R) diagnosis based on a structured clinical interview of the child. Internalizing types of behavior problems and diagnoses were the most frequent. Support was provided for a transactional stress and coping model in delineating the processes associated with child adjustment. In particular, maternal anxiety accounted for 16–33% of the variance in mother-reported internalizing and externalizing behavior problems, respectively, and child pain-coping strategies accounted for 21% of the variance in child-reported adjustment problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
Pope Kenneth S.; Tabachnick Barbara G.; Keith-Spiegel Patricia 《Canadian Metallurgical Quarterly》1987,42(11):993
There is an absence of comprehensive, systematically gathered data concerning psychologists' beliefs about and compliance with ethical principles. Furthermore, we know little about which resources are valued as effective in guiding appropriate behavior. Survey data were collected from 456 APA Division 29 members regarding the degree to which they engaged in each of 83 behaviors and the degree to which they considered each behavior to be ethical. These data were categorized and examined in terms of five principles derived from the Hippocratic oath (avoiding harm, competence, avoiding exploitation, respect, and confidentiality) as well as two additional principles (informed consent; social equity and justice). Twelve of the behaviors were very difficult for participants to evaluate on the basis of ethics. Seven of the 83 behaviors were practiced by over 90% of the participants; 16 by fewer than 10%. Colleagues, the APA Ethical Principles, and internship training were rated as the most helpful resources in guiding behavior; state and federal laws, published research, and local ethics committees were rated least helpful. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
15.
Ohne Zusammenfassung 相似文献
16.
The diffusion coefficient of the cationic dye Anilana Red BL in the anionically modified polyester fiber Dilana has been calculated regarding a general diffusion-immobilization model. In the model the mobile species are distinguished from the immobilized ones. In computations of Sand's equation and experimentally determined sorption isotherm of the dye in the fiber, the rate-of-dyeing curve and the concentration profiles of the dye in the same fiber were employed. The diffusion coefficient of the mobile species of Anilana Red BL in the fiber is two orders of magnitude higher than the average diffusion coefficient obtained from Hill's equation and the apparent diffusion coefficient calculated by the Boltzmann–Matano method. 相似文献
17.
Testing the Ortega hypothesis: Facts and artifacts 总被引:2,自引:0,他引:2
We examine the assumptions and data base used by researchers who have tested the Ortega hypothesis. We find that the assumptions are not supported by the data and that the data are faulty. We conclude that the results are artifactual. We recommend that any policy implemented on the basis of this research be suspended. 相似文献
18.
Glosoff Harriet L.; Herlihy Scott B.; Herlihy Barbara; Spence E. Berton 《Canadian Metallurgical Quarterly》1997,28(6):573
Determining the status of privileged communications between psychologists and clients is a complex task. There is considerable variation across states with respect to the scope of psychologist–client privilege, and several sections of state codes directly and indirectly influence its status. An analysis of state laws related to privileged communication in the psychologist–client relationship is presented and prevalent legal exceptions and trends related to client privilege are discussed. Implications for practice to assist psychologists in balancing their ethical and legal obligations also are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
20.
Thompson Robert J.; Gil Karen M.; Keith Barbara R.; Gustafson Kathryn E.; George Linda K.; Kinney Thomas R. 《Canadian Metallurgical Quarterly》1994,62(4):856
Rates of poor psychological adjustment of children with sickle cell disease remained relatively constant over initial and follow-up assessment points. 50 children (aged 7–12 yrs) and their mothers completed the initial protocol. 30 children completed the follow-up plus 5 additional children and their mothers. These Ss were aged 7–24 yrs at follow-up. With initial levels of adjustment controlled, children's strategies for coping with pain accounted for a significant increment in child-reported symptoms and mother-reported internalizing behavior problems at follow-up beyond the contribution of illness and demographic parameters and follow-up interval. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献