全文获取类型
收费全文 | 32445篇 |
免费 | 1595篇 |
国内免费 | 36篇 |
专业分类
电工技术 | 344篇 |
综合类 | 56篇 |
化学工业 | 7028篇 |
金属工艺 | 608篇 |
机械仪表 | 590篇 |
建筑科学 | 1895篇 |
矿业工程 | 79篇 |
能源动力 | 882篇 |
轻工业 | 2718篇 |
水利工程 | 298篇 |
石油天然气 | 165篇 |
武器工业 | 3篇 |
无线电 | 2336篇 |
一般工业技术 | 6004篇 |
冶金工业 | 5433篇 |
原子能技术 | 211篇 |
自动化技术 | 5426篇 |
出版年
2023年 | 276篇 |
2022年 | 450篇 |
2021年 | 700篇 |
2020年 | 508篇 |
2019年 | 596篇 |
2018年 | 722篇 |
2017年 | 694篇 |
2016年 | 910篇 |
2015年 | 817篇 |
2014年 | 1030篇 |
2013年 | 1935篇 |
2012年 | 1683篇 |
2011年 | 2137篇 |
2010年 | 1516篇 |
2009年 | 1476篇 |
2008年 | 1777篇 |
2007年 | 1657篇 |
2006年 | 1463篇 |
2005年 | 1242篇 |
2004年 | 1109篇 |
2003年 | 959篇 |
2002年 | 922篇 |
2001年 | 560篇 |
2000年 | 531篇 |
1999年 | 548篇 |
1998年 | 561篇 |
1997年 | 487篇 |
1996年 | 497篇 |
1995年 | 457篇 |
1994年 | 449篇 |
1993年 | 440篇 |
1992年 | 394篇 |
1991年 | 236篇 |
1990年 | 322篇 |
1989年 | 327篇 |
1988年 | 274篇 |
1987年 | 301篇 |
1986年 | 292篇 |
1985年 | 315篇 |
1984年 | 273篇 |
1983年 | 262篇 |
1982年 | 247篇 |
1981年 | 214篇 |
1980年 | 178篇 |
1979年 | 189篇 |
1978年 | 169篇 |
1977年 | 141篇 |
1976年 | 141篇 |
1975年 | 140篇 |
1974年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Ruiz John M.; Matthews Karen A.; Scheier Michael F.; Schulz Richard 《Canadian Metallurgical Quarterly》2006,91(2):255
Research suggests that presurgical personality attributes influence postsurgical well-being in both patients and their spouses in the context of coronary artery bypass grafting (CABG) surgery. The authors hypothesized that a spouse's characteristics would influence a partner's psychological well-being, regardless of whether he or she was the patient or the caregiver. In this study, 111 male patients and their caregiver spouses completed measures of neuroticism, optimism, perceived marital satisfaction, and depression prior to elective CABG. Follow-up was conducted at 18 months. As expected, higher caregiver presurgical neuroticism predicted higher patient depressive symptoms at follow-up, with caregiver's concurrent 18-month affect controlled for. Likewise, higher patient presurgical neuroticism predicted higher caregiver depressive symptoms at follow-up. Additionally, higher patient presurgical depressive symptoms and lower presurgical optimism contributed to greater caregiving burden. Relationship satisfaction moderated these effects. These results suggest that partners' personality traits are important determinants of both patients' and their caregiving spouses' well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
992.
Tarter Ralph E.; Kirisci Levent; Kirillova Galina P.; Gavaler Judy; Giancola Peter; Vanyukov Michael M. 《Canadian Metallurgical Quarterly》2007,21(4):462
This investigation determined the influence of testosterone and neurobehavioral disinhibition (ND) on risk for substance use disorder (SUD). Testosterone level during puberty was hypothesized to promote social dominance associated with norm-violating behavior that, in turn, predisposes individuals to use of illicit drugs and, subsequently, SUD. Using a prospective paradigm, the authors recruited 179 boys (mean age=11.62 years, SD=0.88) and followed up when participants were ages 12-14, 16, 19, and 22. Results indicated that social dominance/norm-violating behavior (SD/NVB) at age 16 mediated the association between testosterone level (ages 12-14) and SUD (age 22). In addition, SD/NVB mediated the association between ND and SUD. These findings suggest that development of SUD is influenced by androgen-dependent and neurobehavioral processes via a social motivational style characterized by SD/NVB. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
993.
Andrykowski Michael A.; Carpenter Janet S.; Studts Jamie L.; Cordova Matthew J.; Cunningham Lauren L. C.; Beacham Abbie; Sloan David; Kenady Daniel; McGrath Patrick 《Canadian Metallurgical Quarterly》2002,21(5):485
The impact of benign breast biopsy (BBB) on distress and perceptions of risk for breast cancer (BC) was examined. Interviews were conducted with 100 women shortly after notification of biopsy results and 4 and 8 months post-BBB. Compared with matched healthy comparison (HC) women without BBB, the BBB group evidenced greater BC-specific distress at baseline. BC-specific distress declined after BBB, remaining elevated relative to the HC group at the 8-month follow-up. Dispositional (optimism, informational coping style), demographic (education), clinical (family history of BC), and cognitive (BC risk perception) variables were associated with baseline levels of BC-specific distress or persistence of distress. Results support the monitoring process model (S. M. Miller, 1995) and the cognitive social health information processing model (S. M. Miller, Y. Shoda, & K. Hurley, 1996). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
994.
Michael Yvonne L.; Carlson Nichole E.; Bowen Deborah J.; Ritenbaugh Cheryl 《Canadian Metallurgical Quarterly》2011,30(3):375
[Correction Notice: An erratum for this article was reported in Vol 30(4) of Health Psychology (see record 2011-13978-001). The letter was missing the doi. The correct doi is 10.1037/a0022737. The online version of this article has been corrected.] Responds to the comments by J. C. Coyne and C. Johansen (see record 2011-09497-016) on the current author's original article, "Influence of stressors on breast cancer incidence in the Women's Health Initiative" (see record 2009-03297-001). Coyne and Johansen (2011) took issue with the study conducted by the current authors' group (Michael et al., 2009), which analyzed the interaction between stressful life events and social support on breast cancer risk among 83,334 postmenopausal women enrolled in the Women’s Health Initiative (WHI). While the current authors agree with the Coyne and Johansen that too often null results are difficult to publish due to confirmatory bias that privileges results that support an alternative hypothesis, they strongly disagree with the assertion that their group selectively reported findings, inaccurately reported findings, or provided selective and uncritical reference to the existing literature. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
995.
The MMPI-2 Restructured Form (MMPI-2-RF; Tellegen & Ben-Porath, 2008) was designed to be psychometrically superior to its MMPI-2 counterpart. However, the test has yet to be extensively evaluated in diverse clinical settings. The purpose of this study was to examine the psychometric properties of the MMPI-2-RF Somatic Complaints (RC1) scale in a clinically relevant population. Participants were 399 patients diagnosed with either epilepsy or psychogenic nonepileptic seizures on the basis of video–electroencephalograph monitoring. The internal structure of the MMPI-2-RF was evaluated using taxometric, confirmatory factor analysis, and item response theory procedures. Data from 4 content-specific scales directly related to RC1 (Malaise, Gastrointestinal Complaints, Head Pain Complaints, and Neurological Complaints) indicated that the latent construct of somatization is a dimensional variable with a bifactor structure. However, consistent with the scale's construction, a unidimensional model also provided adequate fit. A 2-parameter logistic item response theory model better accounted for observed item responses than did 1- or 3-parameter models. Results suggest that the RC1 scale is most precise for T score estimates between 55 and 90. Overall, the scale appears to be well suited for the assessment of somatization. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
996.
Gilliom Miles; Shaw Daniel S.; Beck Joy E.; Schonberg Michael A.; Lukon JoElla L. 《Canadian Metallurgical Quarterly》2002,38(2):222
Emotion regulation strategies observed during an age 3 1/2 frustration task were examined in relation to (a) angry affect during the frustration task, (b) child and maternal characteristics at age 1 1/2, and (c) indices of self-control at age 6 in a sample of low-income boys (Ns varied between 189 and 310, depending on the assessment). Shifting attention away from sources of frustration and seeking information about situational constraints were associated with decreased anger. Secure attachment and positive maternal control correlated positively with effective regulatory strategy use. Individual differences in strategy use predicted self-control at school entry, but in specific rather than general ways: Reliance on attention-shifting strategies corresponded with low externalizing problems and high cooperation; reliance on information gathering corresponded with high assertiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
997.
Masatsugu Takamatsu Michael Barrett Randall J. Charbeneau 《Canadian Metallurgical Quarterly》2010,136(5):527-534
Treatment of storm-water runoff may be necessary before discharge to surface waters. In urban areas, space constraints limit selection of conventional treatment systems, and alternative systems are needed. This research program involves design and laboratory testing of a small footprint nonproprietary detention basin which consists of pipes and box culvert sections with a specialized inlet and outlet system. This system can be placed below grade near the roadway section as part of the conventional drainage system and does not require additional right-of-way. A mathematical model, based entirely on hydraulic principles, is developed to estimate particle removal efficiency of the rectangular detention basin for the treatment of storm-water runoff by extending ideal horizontal tank theory under the condition in which water level is varied. A physical model was built in 1/5 scale to measure particle removal performance and validates the conceptual model. Experiments were performed for steady inflow conditions with different inflow rates, durations, and suspended sediment concentrations. Measured time series outflow suspended sediment concentrations and particle removal efficiency compare well with calculated results from the conceptual model. The outflow particle-size distribution can also be estimated using the conceptual model. 相似文献
998.
Eunice C. Nnaji Donald Adgidzi Michael O. Dioha Daniel R.E. Ewim Zhongjie Huan 《The Electricity Journal》2019,32(10):106672
Access to electricity is still a challenge in many parts of sub-Saharan Africa. In Nigeria, over 70% of the rural dwellers do not have access to electricity. The purpose of this paper is to examine the potential of a smart microgrid for off-grid rural electrification in Nigeria. A combination of design thinking and model-based design methodology is employed to select a suitable microgrid configuration and to develop a smart microgrid model. A system consisting of a solar photovoltaic array, battery energy storage and a diesel generator is selected, and the model is developed in Simulink. Demand data from 10 rural communities in Nigeria are used to validate the performance of the model and the potential for demand management is considered. The use of energy efficient light bulbs is found to reduce the peak electricity demand of the case study communities by 42 to 76%. Combining the proposed system with the use of LED bulbs makes the system to have 56 to 81% less net present cost than a system with a diesel generator alone and incandescent light bulbs. The proposed smart microgrid is found to be more suitable for off-grid rural electrification in Nigeria than diesel generators which are currently used for off-grid electrification in Nigeria. 相似文献
999.
Brian M. Kleiner Tonya L. Smith-Jackson Thomas H. Mills III Michael O’Brien Elizabet Haro 《Canadian Metallurgical Quarterly》2008,134(4):273-279
Rapid construction projects and processes will become increasingly important as customers demand better project management performance and globally, as countries plan for and respond to the aftermath of natural and/or unnatural disasters. For use in expedited projects (as well as traditional projects), a rapid universal safety and health system (RUSH) was designed, developed, deployed, and evaluated. For its inaugural application, the RUSH was applied to a 106-hour construction project. Results from an initial application included a safe build in approximately 5?days without recordable incidents. More importantly, lessons were learned by a multidisciplinary team of researchers who observed safety 24/5 for the life of the project. Lessons learned and recommendations for future research are provided as a result of this experience. 相似文献
1000.
Design and management of residential subdivisions are described using a case study in Regina, Saskatchewan. Capital, operation and maintenance costs of physical services and fuel costs for intra-subdivision trips are compared for four subdivision layouts using the procedures. The solar superblock layout is the lowest subdivision layout. Future procedures to assist subdivision design engineers and planners are summarized. 相似文献