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   738篇
  免费   27篇
  国内免费   9篇
电工技术   3篇
综合类   5篇
化学工业   43篇
金属工艺   6篇
机械仪表   2篇
建筑科学   78篇
能源动力   3篇
轻工业   48篇
水利工程   1篇
石油天然气   2篇
武器工业   1篇
无线电   1篇
一般工业技术   15篇
冶金工业   503篇
自动化技术   63篇
  2024年   4篇
  2023年   4篇
  2022年   15篇
  2021年   24篇
  2020年   10篇
  2019年   15篇
  2018年   9篇
  2017年   10篇
  2016年   11篇
  2015年   9篇
  2014年   16篇
  2013年   10篇
  2012年   26篇
  2011年   61篇
  2010年   52篇
  2009年   54篇
  2008年   44篇
  2007年   42篇
  2006年   37篇
  2005年   53篇
  2004年   64篇
  2003年   72篇
  2002年   48篇
  2001年   31篇
  2000年   3篇
  1999年   3篇
  1998年   2篇
  1996年   2篇
  1995年   5篇
  1994年   2篇
  1993年   4篇
  1992年   3篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1979年   1篇
  1973年   1篇
  1971年   1篇
  1968年   2篇
  1967年   2篇
  1966年   1篇
  1964年   2篇
  1962年   1篇
  1961年   2篇
  1959年   1篇
  1957年   1篇
  1956年   3篇
  1955年   1篇
排序方式: 共有774条查询结果,搜索用时 15 毫秒
91.
南楠  詹平 《激光杂志》2014,(1):69-70,72
目的:研究壬基酚通过妊娠期暴露是否会影响F1子代的脑发育。方法:对SD孕鼠染毒NP,从妊娠第7天开始持续到产后第二天,分别提取NP组和对照组F1代2d龄大鼠的脑组织mRNA,表达谱基因芯片检测脑基因的表达。用Q-PCR法验证F1雄性子代大脑泛素特异性蛋白酶8、ATP结合盒转运子和内磺肽蛋白这三个下调基因的表达,然后用Western blotting法检测F1子代大脑泛素特异性蛋白酶8的蛋白表达。结果:ATP结合盒转运子(ATP-binding cassette,ABCA)、内璜肽蛋白(Endosulfine alph,Ensa)、泛素特异性蛋白酶8(Ubiquitin Specific Protease 8,USP8/UBPy)基因和蛋白表达下调。结论:NP可影响神经细胞的正常结构和信号转导功能,并提示可以干扰机体内分泌系统、脂质和能量代谢及一系列正常生理功能。  相似文献   
92.
Intradialytic hypotension (IDH) is a detrimental complication of maintenance hemodialysis, but how it is defined and reported varies widely in the literature. European Best Practice Guideline and Kidney Disease Outcomes Quality Initiative guidelines require symptoms and a mitigating intervention to fulfill the diagnosis, but morbidity and mortality outcomes are largely based on blood pressure alone. Furthermore, little is known about the incidence of asymptomatic hypotension, which may be an important cause of hypoperfusion injury and impaired outcome. Seventy‐seven patients were studied over 456 dialysis sessions. Blood pressure was measured at 15‐minute intervals throughout the session and compared with post‐dialysis symptom questionnaire results using mixed modeling to adjust for repeated measures in the same patient. The frequency of asymptomatic hypotension was estimated by logistic regression using a variety of commonly cited blood pressure metrics that describe IDH. In 113 sessions (25%) where symptoms were recorded on the questionnaire, these appear not to have been reported to dialysis staff. When symptoms were reported (293 sessions [64%]), an intervention invariably followed. Dizziness and cramp were strongly associated with changes in systolic blood pressure (SBP), but not diastolic blood pressure. Nausea occurred more frequently in younger patients but was not associated with falls in blood pressure. Thresholds that maximized the probability of an intervention rather than a session remaining asymptomatic were SBP <100 mmHg or a 20% reduction in SBP from baseline. The probability of SBP falling to <100 mmHg in an asymptomatic session was 0.23. Symptoms are frequently not reported by patients who are hypotensive during hemodialysis, which leads to an underestimation of IDH if symptom‐based definitions are used. A revised definition of IDH excluding patient‐reported symptoms would be in line with literature reporting morbidity and mortality outcomes and include sessions in which potentially detrimental asymptomatic hypotension occurs.  相似文献   
93.
This study examines secondary traumatization among 708 partners and 332 parents of Dutch peacekeepers (i.e., personnel who participated in military actions implemented by international organizations such as the United Nations). Partners or parents of peacekeepers with 4 levels of posttraumatic stress symptoms were compared on posttraumatic stress, health problems, the quality of the marital relationship, and social support. In comparison with partners of peacekeepers without posttraumatic stress disorder (PTSD) symptoms, partners of peacekeepers with PTSD symptoms reported more sleeping and somatic problems, reported more negative social support, and judged the marital relationship as less favorable. No significant differences were found for parents. Thus, peacekeepers' stress reactions were related to various problems of their partners. A systemic approach to the treatment of persons with PTSD appears appropriate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
94.
Several studies have reported an association between hallucinations and tendency to make false alarms in acoustic signal detection tasks. Previous work on patients with schizophrenia has suggested that false recognitions and other types of memory error were positively associated with hallucinations and inversely associated with certain negative symptoms of withdrawal. In this study, 40 patients with schizophrenia were administered a word recognition task. Mixed lists of high- and low-frequency words were presented, then the target words had to be recognized among distractors in immediate and delayed recognition conditions. Hallucination scores were correlated with an increased bias toward false recognitions of nonpresented words. Affective flattening tended to be correlated with a reduced bias toward false recognitions. Anhedonia was significantly correlated with a reduced response bias. Hallucinations and anhedonia therefore presented an opposite association with the response bias. The influence of word frequency and delay on this association is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
95.
Activity restriction is known to mediate the disease-depression relationship. Data from 423 older Israeli adults showed that having to give up activities because of failing health was related to more depressive symptoms (DS), whereas satisfactorily replacing these activities was related to DS levels comparable to those of healthier older adults. Giving up and replacing activities mediated, in part, the effect of functional limitations on DS, after controlling for health status, demographics, and resources. Such questions about activities given up and replaced could contribute to the means of assessing the extent and impact of functional limitations on older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
96.
Cross-national differences in the prevalence of psychopathy have been reported. This study examined whether rater effects could account for these differences. Psychopathy was assessed with the Psychopathy Checklist-Revised (PCL-R; R. D. Hare, 1991). Videotapes of 6 Scottish prisoners and 6 Canadian prisoners were rated by 10 Scottish and 10 Canadian raters. No significant main or interaction effects involving the nationality of raters were detected at the level of full scores or factor scores. Using a generalizability theory approach, it was demonstrated that the interrater reliability of total scores was good, that is, the proportion of variance in test scores attributable to raters was small. The interrater reliability of factor scores was lower, typically falling in the fair range. Overall, the results suggest that the reported cross-national differences are more likely to be in the expression of the disorder rather than in the eye of the beholder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
97.
Community and high-risk sample studies suggest that alcohol dependence is relatively stable and chronic. By contrast, epidemiological studies demonstrate a strong age-graded decline whereby alcohol dependence tends to peak in early adulthood and declines thereafter. The authors identified the latent trajectory structure of past-year alcohol dependence to investigate (a) whether the syndrome is characterized by symptom profiles and (b) the extent to which the syndrome is stable and persistent. Data from current drinkers (N = 4,003) in the National Longitudinal Survey of Youth were analyzed across two waves: 1989 (ages 24-32 years) and 1994 (ages 29-37 years). Three classes of alcohol dependence were observed; symptom endorsement probabilities increased across successively severe classes. Latent transition analyses showed high rates of stability, supporting alcohol dependence as a relatively chronic condition. Although there was evidence of progression to more severe dependence, there was greater syndrome remission. Trajectory classes and transition probabilities were generalizable across race and sex and, to a lesser extent, age cohort and family history of alcoholism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
98.
Parental divorce is associated with problematic offspring adjustment, but the relation may be due to shared genetic or environmental factors. One way to test for these confounds is to study offspring of twins discordant for divorce. The current analyses used this design to separate the mechanisms responsible for the association between parental divorce, experienced either before or after the age of 16, and offspring well-being. The results were consistent with a causal role of divorce in earlier initiation of sexual intercourse and emotional difficulties, in addition to a greater probability of educational problems, depressed mood, and suicidal ideation. In contrast, the increased risk for cohabitation and earlier initiation of drug use was explained by selection factors, including genetic confounds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
99.
100.
[Correction Notice: An erratum for this article was reported in Vol 18(1) of Journal of Family Psychology (see record 2007-16896-001). On page 551, in Table 2, two values are listed incorrectly. In row 17, Early Child Externalizing (K, Grade 2), the correlation coefficients in columns 4 and 5 should be transposed to read -.087 in column 4 (People in My Life Communication) and -.208 in column 5 (Inventory of Parent Experiences Community Support).] Drawing on a normative sample of 224 youth and their biological mothers, this study tested 4 family variables as potential mediators of the relationship between maternal depressive symptoms in early childhood and child psychological outcomes in preadolescence. The mediators examined included mother-child communication, the quality of the mother-child relationship, maternal social support, and stressful life events in the family. The most parsimonious structural equation model suggested that having a more problematic mother-child relationship mediated disruptive behavior-disordered outcomes for youths, whereas less maternal social support mediated the development of internalizing disorders. Gender and race were tested as moderators, but significant model differences did not emerge between boys and girls or between African American and Caucasian youths. (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