全文获取类型
收费全文 | 2712篇 |
免费 | 92篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 35篇 |
综合类 | 1篇 |
化学工业 | 451篇 |
金属工艺 | 33篇 |
机械仪表 | 51篇 |
建筑科学 | 166篇 |
矿业工程 | 7篇 |
能源动力 | 72篇 |
轻工业 | 223篇 |
水利工程 | 23篇 |
石油天然气 | 13篇 |
无线电 | 180篇 |
一般工业技术 | 423篇 |
冶金工业 | 732篇 |
原子能技术 | 22篇 |
自动化技术 | 375篇 |
出版年
2022年 | 15篇 |
2021年 | 29篇 |
2020年 | 32篇 |
2019年 | 40篇 |
2018年 | 52篇 |
2017年 | 45篇 |
2016年 | 50篇 |
2015年 | 37篇 |
2014年 | 53篇 |
2013年 | 138篇 |
2012年 | 111篇 |
2011年 | 165篇 |
2010年 | 100篇 |
2009年 | 113篇 |
2008年 | 139篇 |
2007年 | 140篇 |
2006年 | 112篇 |
2005年 | 119篇 |
2004年 | 97篇 |
2003年 | 79篇 |
2002年 | 78篇 |
2001年 | 56篇 |
2000年 | 44篇 |
1999年 | 53篇 |
1998年 | 117篇 |
1997年 | 67篇 |
1996年 | 60篇 |
1995年 | 42篇 |
1994年 | 42篇 |
1993年 | 29篇 |
1992年 | 37篇 |
1991年 | 31篇 |
1990年 | 27篇 |
1989年 | 35篇 |
1988年 | 26篇 |
1987年 | 34篇 |
1986年 | 25篇 |
1985年 | 25篇 |
1984年 | 26篇 |
1983年 | 26篇 |
1982年 | 14篇 |
1981年 | 17篇 |
1980年 | 20篇 |
1979年 | 18篇 |
1978年 | 19篇 |
1977年 | 13篇 |
1976年 | 41篇 |
1975年 | 19篇 |
1974年 | 11篇 |
1973年 | 15篇 |
排序方式: 共有2807条查询结果,搜索用时 15 毫秒
991.
The phosphatase Cdc14 triggers mitotic exit by reversal of Cdk-dependent phosphorylation 总被引:1,自引:0,他引:1
R Visintin K Craig ES Hwang S Prinz M Tyers A Amon 《Canadian Metallurgical Quarterly》1998,2(6):709-718
The minor U12-dependent class of eukaryotic nuclear pre-mRNA introns is spliced by a distinct spliceosomal mechanism that requires the function of U11, U12, U5, U4atac, and U6atac snRNAs. Previous work has shown that U11 snRNA plays a role similar to U1 snRNA in the major class spliceosome by base pairing to the conserved 5' splice site sequence. Here we show that U6atac snRNA also base pairs to the 5' splice site in a manner analogous to that of U6 snRNA in the major class spliceosome. We show that splicing defective mutants of the 5' splice site can be activated for splicing in vivo by the coexpression of compensatory U6atac snRNA mutants. In some cases, maximal restoration of splicing required the coexpression of compensatory U11 snRNA mutants. The allelic specificity of mutant phenotype suppression is consistent with Watson-Crick base pairing between the pre-mRNA and the snRNAs. These results provide support for a model of the RNA-RNA interactions at the core of the U12-dependent spliceosome that is strikingly similar to that of the major class U2-dependent spliceosome. 相似文献
992.
Detection of cardiac troponin I (cTnI) in patients suspected of having an acute coronary syndrome is highly predictive for an adverse outcome. We evaluated a bedside test for cTnI that uses a polyclonal capture antibody and two monoclonal indicator antibodies. Clinical studies were performed in patients with acute coronary syndrome and patients with chest pain but no evidence of acute myocardial injury. The whole-blood, 15-minute assay had a concordance of 98.9% with an ELISA for cTnI and a detection limit of 0.14 microg/L, and the device tolerated temperatures between 4 degrees C and 37 degrees C. Diagnostic sensitivity for myocardial infarction at arrival (3.5 +/- 2.7 h after onset of symptoms) was 60% [creatine kinase isoenzyme MB (CK-MB) mass, 48%; CK activity, 36%; P < 0.01], and 4 h later, diagnostic sensitivity was 98% (CK-MB mass, 91%; CK activity, 61%; P < 0.01). In 38% of the patients with unstable angina, at least one positive cTnI test was found (CK-MB mass, 4%; CK activity, 2%). No false-positive test results were found in renal failure or injury of skeletal muscle. We conclude that the diagnostic efficacy of the cTnI rapid test was comparable with the cTnI ELISA and superior to CK-MB determination. Therefore, this device could facilitate decision-making in patients with chest pain at the point of care. 相似文献
993.
OBJECTIVE: To assess time trends in the frequency of norfloxacin and ciprofloxacin resistance of bacteria isolated from urine culture. METHODS: Results of all urine cultures with a bacterial growth of at least 10(5) colony-forming units per milliliter, performed at the Renal Service of the Federal University of Bahia, Brazil, from 1983 to 1994 were analyzed. The bacteria considered for this analysis were those most often isolated: Escherichia coli (n = 668), Klebsiella spp. (n = 286), Staphylococcus spp. (n = 186), Proteus spp. (n = 135) and Enterobacter spp. (n = 129). RESULTS: The frequencies of norfloxacin resistance for the periods 1983-1986, 1987-1990 and 1991-1994 were 3.2%, 5.9% and 9.1%, respectively (p-value < 0.05). The most pronounced increases in the frequencies of norfloxacin-resistance were observed for Klebsiella spp. and Enterobacter spp. The frequency of ciprofloxacin resistance was 7.4% in the period 1985-1989 and 16.5% in the period 1990-1994 (p-value < 0.05). This time trend in ciprofloxacin resistance was more striking for Enterobacter spp. and Staphylococcus spp. CONCLUSION: The results show a gradual increase in the frequency of norfloxacin and ciprofloxacin resistance of the bacteria most commonly isolated from urine cultures. The influence of previous treatment with quinolones and characteristics of the infecting bacteria on these findings are important questions to to be addressed in future investigations. 相似文献
994.
995.
Life cycle cost or total cost analysis of a facility begins with the initial design concept and ends with the decommissioning of the facility. Decisions made during the design and construction phases routinely consider only the construction costs when analyzing the constructability of the project. Often the impacts of such decisions on the maintenance requirements for the facility are not fully appreciated and are therefore not formally addressed. The concept of “maintainability” addresses this concern and is a logical extension of the constructability concept. As such, maintainability may be incorporated as a part of the formal constructability review process (CRP). This article describes a model format for incorporating the best practices for maintainability into the CRP. The added life cycle value of incorporating maintainability into the CRP can only be assessed by analysis of accurate and complete maintenance cost data. Insights from such an analysis may facilitate more accurate estimates of the total costs of facilities. 相似文献
996.
Poteat V. Paul; Mereish Ethan H.; DiGiovanni Craig D.; Koenig Brian W. 《Canadian Metallurgical Quarterly》2011,58(4):597
Many adolescents experience peer victimization, which often can be homophobic. Applying the minority stress model with attention to intersecting social identities, this study tested the effects of general and homophobic victimization on several educational outcomes through suicidality and school belonging among 15,923 adolescents in Grades 7 through 12 on account of their sexual orientation and race/ethnicity. Parent support also was tested as a moderator of these effects. Homophobic victimization had different effects on suicidality across groups, indicating the importance of considering individuals' multiple social identities. However, homophobic victimization had universal negative effects on school belonging for all groups. Nearly all indirect effects of general and homophobic victimization on reported grades, truancy, and importance of graduating were significant through suicidality and school belonging across groups. Parent support was most consistent in moderating the effects of general and homophobic victimization on suicidality for heterosexual White and racial/ethnic minority youth. In nearly all cases, it did not moderate the effects of general or homophobic victimization for lesbian, gay, bisexual, transgender, and questioning youth. Furthermore, in most cases, parent support did not moderate the effects of general or homophobic victimization on school belonging. Findings underscore the need for counseling psychologists to work with parents of all youth on ways to provide support to those who experience homophobic victimization. Furthermore, they highlight the need for counseling psychologists to be involved as social justice advocates in the passage and implementation of school policies that address homophobic bullying and other forms of bias-based bullying and harassment. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
997.
Wallace J. Craig; Johnson Paul D.; Mathe Kimberly; Paul Jeff 《Canadian Metallurgical Quarterly》2011,96(4):840
The authors proposed and tested a model in which data were collected from managers (n = 539) at 116 corporate-owned quick service restaurants to assess the structural and psychological empowerment process as moderated by shared-felt accountability on indices of performance from a managerial perspective. The authors found that empowering leadership climate positively relates to psychological empowerment climate. In turn, psychological empowerment climate relates to performance only under conditions of high-felt accountability; it does not relate to performance under conditions of low-felt accountability. Overall, the present results indicate that the quick-service restaurant managers, who feel more empowered, operate restaurants that perform better than managers who feel less empowered, but only when those empowered managers also feel a high sense of accountability. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
998.
Hadjistavropoulos Thomas; Craig Kenneth D.; Duck Steve; Cano Annmarie; Goubert Liesbet; Jackson Philip L.; Mogil Jeffrey S.; Rainville Pierre; Sullivan Michael J. L.; de C. Williams Amanda C.; Vervoort Tine; Fitzgerald Theresa Dever 《Canadian Metallurgical Quarterly》2011,137(6):910
We present a detailed framework for understanding the numerous and complicated interactions among psychological and social determinants of pain through examination of the process of pain communication. The focus is on an improved understanding of immediate dyadic transactions during painful events in the context of broader social phenomena. Fine-grain consideration of social transactions during pain leads to an appreciation of sociobehavioral events affecting both suffering persons as well as caregivers. Our examination considers knowledge from a variety of perspectives, including clinical health psychology, social and developmental processes, evolutionary psychology, communication studies, and behavioral neuroscience. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
999.
Ferdenzi Camille; Schirmer Annett; Roberts S. Craig; Delplanque Sylvain; Porcherot Christelle; Cayeux Isabelle; Velazco Maria-Inès; Sander David; Scherer Klaus R.; Grandjean Didier 《Canadian Metallurgical Quarterly》2011,11(5):1168
Do affective responses to odors vary as a function of culture? To address this question, we developed two self-report scales in the United Kingdom (Liverpool: LEOS) and in Singapore (city of Singapore: SEOS), following the same procedure as used in the past to develop the Geneva Emotion and Odor Scale (GEOS: Chrea, Grandjean, Delplanque et al., 2009). The final scales were obtained by a three-step reduction of an initial pool of 480 affective terms, retaining only the most relevant terms to describe odor-related subjective affective states and comprised of six (GEOS) or seven affective dimensions (LEOS and SEOS). These included dimensions that were common to the three cultures (Disgust, Happiness Well-being, Sensuality Desire, and Energy), common to the two European samples (Soothing Peacefulness), and dimensions that were culture specific (Sensory Pleasure in Geneva; Nostalgia and Hunger Thirst in Liverpool; Intellectual Stimulation, Spirituality, and Negative Feelings in Singapore). A comparative approach showed that the dimensional organization of odor-related affective terms in a given culture better explained data variability for that culture than data variability for the other cultures, thus highlighting the importance of culture-specific tools in the investigation of odor-related affect. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
1000.
The current study explored psychological symptoms, symptom severity, and suicide risk in a national sample (N = 628) of student veterans. We hypothesized that the rates, types, and severity of problems experienced by student veterans on campus would in many ways mirror those reported by active duty service members as well as the Operation Iraqi Freedom/Operation Enduring Freedom veteran population. Almost 35% of the sample experienced “severe anxiety,” 24% experienced “severe depression,” and almost 46% experienced significant symptoms of posttraumatic stress disorder. Of particular concern, there were significant numbers of participants thinking about suicide (46%), with 20% having a plan, 10.4% thinking about suicide “often or very often,” 7.7% making an attempt, and 3.8% believing that suicide is either “likely” or “very likely.” Implications of the findings are discussed, with a particular focus on college and university campuses. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献