首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1751篇
  免费   54篇
电工技术   21篇
化学工业   256篇
金属工艺   12篇
机械仪表   14篇
建筑科学   111篇
能源动力   33篇
轻工业   171篇
水利工程   31篇
石油天然气   2篇
武器工业   1篇
无线电   75篇
一般工业技术   246篇
冶金工业   606篇
原子能技术   2篇
自动化技术   224篇
  2024年   1篇
  2023年   16篇
  2022年   42篇
  2021年   28篇
  2020年   26篇
  2019年   26篇
  2018年   18篇
  2017年   23篇
  2016年   55篇
  2015年   21篇
  2014年   37篇
  2013年   100篇
  2012年   90篇
  2011年   132篇
  2010年   106篇
  2009年   98篇
  2008年   133篇
  2007年   139篇
  2006年   97篇
  2005年   79篇
  2004年   60篇
  2003年   59篇
  2002年   66篇
  2001年   32篇
  2000年   33篇
  1999年   28篇
  1998年   54篇
  1997年   37篇
  1996年   25篇
  1995年   21篇
  1994年   16篇
  1993年   19篇
  1992年   18篇
  1991年   4篇
  1990年   9篇
  1989年   6篇
  1988年   8篇
  1987年   7篇
  1986年   7篇
  1985年   4篇
  1984年   3篇
  1983年   2篇
  1982年   4篇
  1981年   4篇
  1980年   4篇
  1979年   2篇
  1978年   2篇
  1976年   3篇
  1966年   1篇
排序方式: 共有1805条查询结果,搜索用时 15 毫秒
31.
In studies of episodic recognition memory, low-frequency words (LF) have higher hit rates (HR) and lower false alarm rates (FAR) than do high-frequency words (HF), which is known as the mirror pattern. A few findings have suggested that requiring a task at study may reduce or eliminate the LF-HR advantage without altering the LF-FAR effect. Other studies have suggested that the size of the LF-HR advantage interacts with study time. To explore such findings more thoroughly and relate them to theory, the authors conducted 5 experiments, varying study time and study task. The full mirror pattern was found only in 2 cases: the standard condition requiring study for a later memory test and a condition requiring a judgment about unusual letters. The authors explain their findings in terms of the encoding of distinctive features and discuss the implications for current theories of recognition memory and the word frequency effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
32.
As the Internet has changed communication, commerce, and the distribution of information, so too it is changing psychological research. Psychologists can observe new or rare phenomena online and can do research on traditional psychological topics more efficiently, enabling them to expand the scale and scope of their research. Yet these opportunities entail risk both to research quality and to human subjects. Internet research is inherently no more risky than traditional observational, survey, or experimental methods. Yet the risks and safeguards against them will differ from those characterizing traditional research and will themselves change over time. This article describes some benefits and challenges of conducting psychological research via the Internet and offers recommendations to both researchers and institutional review boards for dealing with them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
33.
34.
业界人士和分析师向TWICE表示,正如视频游戏注重逼真效果一样,个人导航设备(PND)也会在其图示上增加逼真度. 他们说,个人导航设备产品下一步要升级的技术包括三维高真度的街面视图和鸟瞰图.ABI研究预测,到2012年,北美80%的PND产品以及欧洲90~95%的PND产品都会带有某种类似高真相片的显示器.  相似文献   
35.
Pregnancy is characterized by adaptations in the function of several maternal body systems that ensure the development of the fetus whilst maintaining health of the mother. The renal system is responsible for water and electrolyte balance, as well as waste removal. Thus, it is imperative that structural and functional changes occur in the kidney during pregnancy. However, our knowledge of the precise morphological and molecular mechanisms occurring in the kidney during pregnancy is still very limited. Here, we investigated the changes occurring in the mouse kidney during pregnancy by performing an integrated analysis involving histology, gene and protein expression assays, mass spectrometry profiling and bioinformatics. Data from non-pregnant and pregnant mice were used to identify critical signalling pathways mediating changes in the maternal kidneys. We observed an expansion of renal medulla due to proliferation and infiltration of interstitial cellular constituents, as well as alterations in the activity of key cellular signalling pathways (e.g., AKT, AMPK and MAPKs) and genes involved in cell growth/metabolism (e.g., Cdc6, Foxm1 and Rb1) in the kidneys during pregnancy. We also generated plasma and urine proteomic profiles, identifying unique proteins in pregnancy. These proteins could be used to monitor and study potential mechanisms of renal adaptations during pregnancy and disease.  相似文献   
36.
Objective: The authors conducted a meta-analysis of empirical studies investigating associations between indices of posttraumatic stress disorder (PTSD) and intimate relationship problems to empirically synthesize this literature. Method: A literature search using PsycINFO, Medline, Published International Literature on Traumatic Stress (PILOTS), and Dissertation Abstracts was performed. The authors identified 31 studies meeting inclusion criteria. Results: True score correlations (ρ) revealed medium-sized associations between PTSD and intimate relationship discord (ρ = .38, N = 7,973, K = 21), intimate relationship physical aggression perpetration (ρ = .42, N = 4,630, K = 19), and intimate relationship psychological aggression perpetration (ρ = .36, N = 1,501, K = 10). The strength of the association between PTSD and relationship discord was higher in military (vs. civilian) samples, and when the study was conducted in the United States (vs. other country), and the study represented a doctoral dissertation (vs. published article). The strength of the association between PTSD and physical aggression was higher in military (vs. civilian) samples, males (vs. females), community (vs. clinical) samples, studies examining PTSD symptom severity (vs. diagnosis), when the physical aggression measure focused exclusively on severe violence (vs. a more inclusive measure), and the study was published (vs. dissertation). For the PTSD–psychological aggression association, 98% of the variance was accounted for by methodological artifacts such as sampling and measurement error; consequently, no moderators were examined in this relationship. Conclusions: Findings highlight a need for the examination of models explaining the relationship difficulties associated with PTSD symptomatology and interventions designed to treat problems in both areas. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
37.
Understanding how ethnic identities develop in adolescence is currently limited by a reliance on self-report paper-and-pencil measures. This mixed-methods study presents a novel response time measure, the Multiethnic Identities Processing Task (MIPT), to quantify bicultural adolescents' implicit identifications with ethnic and racial identity labels. Eighty-four adolescents (age 14–21 years) of diverse ethnic and racial backgrounds self-identified as bicultural or not bicultural and described their ethnic identities, pride, and ethnic centrality during a brief interview. Participants were assigned to complete either the interview (self-prime) or the MIPT (no prime) first. Results indicate that bicultural adolescents readily endorsed a variety of ethnic and racial labels in the MIPT, reflecting their multifaceted identities. Younger bicultural adolescents showed a large inhibited response to the label “White,” indicating some hesitation in deciding whether the label was “like me” or “not like me.” Heart rate monitoring and qualitative analyses of interviews provide some insight into this pattern of results. Findings are discussed with respect to developmental theory, and the strengths of using both implicit and explicit measures to understand multiethnic identity development in adolescence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
38.
Objective: The ability to select what is important to remember, to attend to this information, and to recall high-value items leads to the efficient use of memory. The present study examined how children with and without attention-deficit/hyperactivity disorder (ADHD) performed on an incentive-based selectivity task in which to-be-remembered items were worth different point values. Method: Participants were 6–9 year old children with ADHD (n = 57) and without ADHD (n = 59). Using a selectivity task, participants studied words paired with point values and were asked to maximize their score, which was the overall value of the items they recalled. This task allows for measures of memory capacity and the ability to selectively remember high-value items. Results: Although there were no significant between-groups differences in the number of words recalled (memory capacity), children with ADHD were less selective than children in the control group in terms of the value of the items they recalled (control of memory). All children recalled more high-value items than low-value items and showed some learning with task experience, but children with ADHD Combined type did not efficiently maximize memory performance (as measured by a selectivity index) relative to children with ADHD Inattentive type and healthy controls, who did not differ significantly from one another. Conclusions: Children with ADHD Combined type exhibit impairments in the strategic and efficient encoding and recall of high-value items. The findings have implications for theories of memory dysfunction in childhood ADHD and the key role of metacognition, cognitive control, and value-directed remembering when considering the strategic use of memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
39.
Problem, research strategy, and findings: Local governments across the United States have for decades relied on the autocentric level of service (LOS) metric to analyze and impose exactions for the transportation impacts of land use developments. In California, LOS has dominated transportation impact analysis under the state’s project-level environmental review law. In that role, LOS has exacerbated the state’s notoriously tortuous development approval processes, particularly in urban areas. But LOS is on its way out. The state recently replaced LOS with vehicle miles traveled (VMT) as the primary measure—and basis for mitigation—of transportation impacts under the California Environmental Quality Act. Local governments must make the switch by July 1, 2020. We use a historical counterfactual approach to assess how replacing LOS with VMT could have affected the approval process for 153 land development projects over 16?years in the city of Los Angeles. We find that most projects could have benefited from at least some environmental review streamlining under the VMT-based framework recommended by the state, including more than 75% of residential-containing projects.

Takeaway for practice: Our results suggest that swapping LOS for VMT could reduce the environmental review burden for development in low-VMT urban areas and provide at least some of the approval process streamlining necessary to increase housing production in California. Similar impacts from an LOS-to-VMT switch could also potentially accrue outside of California under the right conditions, but more research is needed.  相似文献   

40.
Attributional theory and empirical evidence suggest that a tendency to make stable, global self-causal attributions for undesirable events is associated with negative outcomes. However, existing self-report measures of parental attributions do not account for the possibility that dysfunctional parent-causal attributions for child misbehavior might be important predictors of poor family functioning. To address these concerns, the authors developed and tested a new measure of both parent-causal and child-responsible attributions for child misbehavior in a sample of 453 community couples. Structural validity, convergent validity, discriminant validity, internal consistency, and temporal stability of the new measure were examined. As expected, confirmatory factor analysis resulted in 2 factors, Child-Responsible (9 items) and Parent-Causal (7 items); the final model was cross-validated in a holdout sample. The final scale demonstrated adequate internal consistency (αs = .81–.90), test–retest reliability (rs = .55–.76), and convergent and discriminant validity. Dysfunctional parent-causal and child-responsible attributions significantly predicted parental emotional problems, ineffective discipline, parent–child physical aggression, and low parenting satisfaction. Associations with parent–child aggression and parenting satisfaction were generally larger than with partner aggression and relationship satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号