全文获取类型
收费全文 | 26810篇 |
免费 | 772篇 |
国内免费 | 33篇 |
专业分类
电工技术 | 329篇 |
综合类 | 14篇 |
化学工业 | 5927篇 |
金属工艺 | 519篇 |
机械仪表 | 464篇 |
建筑科学 | 1160篇 |
矿业工程 | 332篇 |
能源动力 | 650篇 |
轻工业 | 1726篇 |
水利工程 | 226篇 |
石油天然气 | 246篇 |
无线电 | 1712篇 |
一般工业技术 | 4087篇 |
冶金工业 | 6242篇 |
原子能技术 | 269篇 |
自动化技术 | 3712篇 |
出版年
2022年 | 246篇 |
2021年 | 411篇 |
2020年 | 266篇 |
2019年 | 346篇 |
2018年 | 422篇 |
2017年 | 369篇 |
2016年 | 485篇 |
2015年 | 391篇 |
2014年 | 614篇 |
2013年 | 1653篇 |
2012年 | 938篇 |
2011年 | 1202篇 |
2010年 | 923篇 |
2009年 | 972篇 |
2008年 | 1148篇 |
2007年 | 1064篇 |
2006年 | 973篇 |
2005年 | 884篇 |
2004年 | 746篇 |
2003年 | 712篇 |
2002年 | 707篇 |
2001年 | 487篇 |
2000年 | 395篇 |
1999年 | 450篇 |
1998年 | 450篇 |
1997年 | 443篇 |
1996年 | 477篇 |
1995年 | 448篇 |
1994年 | 452篇 |
1993年 | 441篇 |
1992年 | 433篇 |
1991年 | 271篇 |
1990年 | 413篇 |
1989年 | 389篇 |
1988年 | 337篇 |
1987年 | 409篇 |
1986年 | 349篇 |
1985年 | 444篇 |
1984年 | 466篇 |
1983年 | 402篇 |
1982年 | 376篇 |
1981年 | 300篇 |
1980年 | 299篇 |
1979年 | 358篇 |
1978年 | 303篇 |
1977年 | 241篇 |
1976年 | 227篇 |
1975年 | 247篇 |
1974年 | 217篇 |
1973年 | 225篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
Emery Robert E.; Matthews Sheila G.; Kitzmann Katherine M. 《Canadian Metallurgical Quarterly》1994,62(1):124
A 1-yr follow-up study was conducted on families randomly assigned to settle custody disputes either in mediation or through adversary procedures. Consistent with Time 1 reports, at Time 2 fathers who mediated were substantially more satisfied than were fathers who litigated. Fathers who mediated also complied more with child support orders. Contrary to prediction, the greater satisfaction and compliance of fathers did not lead to increased satisfaction among mothers who mediated. In contrast to Time 1, at follow-up mothers who mediated were significantly less satisfied than were mothers who litigated, but selective attrition may account for these differences. The psychological adjustment of mothers and fathers was not significantly different between settlement groups at Time 2, but mothers in both groups reported less satisfaction with dispute settlement and less dysphoria at Time 2 than they had reported at Time 1. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
162.
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
163.
Cats (Felis catus) find an object when it is visibly moved behind a succession of screens. However, when the object is moved behind a container and is invisibly transferred from the container to the back of a screen, cats try to find the object at or near the container rather than at the true hiding place. Four experiments were conducted to study search behavior and working memory in visible and invisible displacement tests of object permanence. Exp 1 compared performance in single and in double visible displacement trials. Exp 2 analyzed search behavior in invisible displacement tests and in analogs using a transparent container. Exps 3 and 4 tested predictions made from Exps 1 and 2 in a new situation of object permanence. Results showed that only the position changes that cats have directly perceived are encoded and activated in working memory because they are unable to represent or infer invisible movements. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
164.
Previous research on adaptation to visual-motor rearrangement suggests that the CNS represents accurately only 1 visual–motor mapping at a time. This idea was examined in 3 experiments where Ss tracked a moving target under repeated alternations between 2 initially interfering mappings (the "normal" mapping characteristic of computer input devices and a 108° rotation of the normal mapping). Alternation between the 2 mappings led to significant reduction in error under the rotated mapping and significant reduction in the adaptation aftereffect ordinarily caused by switching between mappings. Color as a discriminative cue, interference vs decay in adaptation aftereffect, and intermanual transfer were also examined. The results reveal a capacity for multiple concurrent visual–motor mappings, possibly controlled by a parametric process near the motor output stage of processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
165.
Lewinsohn Peter M.; Roberts Robert E.; Seeley John R.; Rohde Paul; Gotlib Ian H.; Hops Hyman 《Canadian Metallurgical Quarterly》1994,103(2):302
In a prospective study of adolescent depression, adolescents (N?=?1,508) were assessed at Time 1 and after 1 yr (Time 2) on psychosocial variables hypothesized to be associated with depression. Most psychosocial variables were associated with current (n?=?45) depression. Formerly depressed adolescents (n?=?217) continued to differ from never depressed controls on many of the psychosocial variables. Many of the depression-related measures also acted as risk factors for future depression (n?=?112), especially past depression, current other mental disorders, past suicide attempt, internalizing behavior problems, and physical symptoms. Young women were more likely to be, to become, and to have been depressed. Controlling for the psychosocial variables eliminated the gender difference for current and future but not for past depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
166.
Krueger Robert F.; Schmutte Pamela S.; Caspi Avshalom; Moffitt Terrie E.; Campbell Kathleen; Silva Phil A. 《Canadian Metallurgical Quarterly》1994,103(2):328
Is there a relationship between personality and criminal behavior? We addressed this question in a representative birth cohort of 862 male and female 18-yr-olds. Personality was assessed with the Multidimensional Personality Questionnaire (MPQ). The MPQ measures 10 relatively independent personality traits and was not designed to identify offenders. Delinquency was assessed via 3 data sources: self-reports, informant reports, and official records. Variable-centered analyses revealed that MPQ scales indexing negative emotionality and behavioral constraint were consistent predictors of delinquency across the 3 data sources. Person-centered analyses revealed that youths abstaining from delinquency were uniquely characterized by low interpersonal potency. Youths involved in extensive delinquency were uniquely characterized by feelings of alienation, lack of social closeness and risk taking. Advances in understanding criminal behavior can be made through research that places the personality-delinquency link in a developmental context. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
167.
F. L. Schmidt and J. E. Hunter (1989) critiqued the within-group interrater reliability statistic (rwg) described by L. R. James et al (1984). S. W. Kozlowski and K. Hattrup (1992) responded to the Schmidt and Hunter critique and argued that rwg is a suitable index of interrater agreement. This article focuses on the interpretation of rwg as a measure of agreement among judges' ratings of a single target. A new derivation of rwg is given that underscores this interpretation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
168.
169.
Brefeldin A (BFA) has been reported to cause disassembly of the Golgi. We have used three-dimensional (3-D) high-resolution scanning electron microscopy (HRSEM) to investigate these effects in human skin fibroblast cells. The spontaneous reassembly during prolonged exposure to BFA and some effects of forskolin were observed. A BFA concentration of 5μg/ml caused Golgi complexes to become vesicular, resulting in a progressive decrease in the size of the Golgi. Morphologic changes were visible within 2 min of BFA incubation, and by 30 min no identifiable Golgi could be found. Spontaneous reassembly of the Golgi apparatus upon the removal of the BFA or with continued long-term exposure with BFA could not be confirmed. Preliminary experiments with forskolin were not effective in reversing or inhibiting the effects of BFA in human fibroblast cells grown in culture. This inability for spontaneous reassembly and nonreversal by forskolin may reflect a differential effect of BFA in various cell types. HRSEM has proven to be useful for observing 3-D morphologic effects of BFA in Golgi. 相似文献
170.
P. Rossi N. Godart J. L. Robert J. P. Gervais D. Bruhat 《Materials and Structures》1994,27(9):510-514
The physical origins of the basic creep of concrete are still poorly understood even though some researchers have proposed hypotheses concrening the physical mechanisms that govern this delayed behaviour of concrete. A very complete summing up of these hypotheses was produced, in the past, by, Neville; he shows that none of them, provides a satisfactory explanation of the bulk of basic creep. More recently, Rossi has proposed a new hypothesis, which has been the subject of several articles. This article concerns the use of the acoustic emission technique as a ‘tool’ to provide information on the pertinence of the physical hypothesis advanced by Rossi. The counting of the total number of acoustic events together with a frequency analysis of the acoustic emission signals indicate that there is a strong correlation between the basic creep of concrete and the creation of microcracks in the material. 相似文献