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   1091篇
  免费   31篇
  国内免费   3篇
电工技术   8篇
综合类   4篇
化学工业   231篇
金属工艺   8篇
机械仪表   14篇
建筑科学   63篇
矿业工程   2篇
能源动力   19篇
轻工业   106篇
水利工程   7篇
无线电   53篇
一般工业技术   148篇
冶金工业   332篇
原子能技术   1篇
自动化技术   129篇
  2023年   13篇
  2022年   8篇
  2021年   31篇
  2020年   12篇
  2019年   14篇
  2018年   19篇
  2017年   17篇
  2016年   24篇
  2015年   11篇
  2014年   30篇
  2013年   52篇
  2012年   47篇
  2011年   65篇
  2010年   46篇
  2009年   36篇
  2008年   57篇
  2007年   48篇
  2006年   50篇
  2005年   36篇
  2004年   34篇
  2003年   16篇
  2002年   37篇
  2001年   26篇
  2000年   19篇
  1999年   26篇
  1998年   34篇
  1997年   32篇
  1996年   25篇
  1995年   21篇
  1994年   25篇
  1993年   24篇
  1992年   17篇
  1991年   8篇
  1990年   18篇
  1989年   8篇
  1988年   10篇
  1987年   9篇
  1986年   9篇
  1985年   12篇
  1984年   9篇
  1983年   8篇
  1982年   8篇
  1981年   8篇
  1980年   11篇
  1979年   5篇
  1978年   6篇
  1977年   10篇
  1976年   13篇
  1975年   7篇
  1974年   3篇
排序方式: 共有1125条查询结果,搜索用时 46 毫秒
1.
Soybean oil hydrogenation alters the linolenic acid molecule to prevent the oil from becoming rancid, however, health reports have indicated trans-fat caused by hydrogenation, is not generally regarded as safe. Typical soybeans contain approximately 80 g kg−1 to 120 g kg−1 linolenic acid and 240 g kg−1 of oleic acid. In an effort to accommodate the need for high-quality oil, the United Soybean Board introduced an industry standard for a high oleic acid greater than 750 g kg−1 and linolenic acid less than 30 g kg−1 oil. By combing mutations in the soybean plant at four loci, FAD2-1A and FAD2-1B, oleate desaturase genes and FAD3A and FAD3C, linoleate desaturase genes, and seed oil will not require hydrogenation to prevent oxidation and produce high-quality oil. In 2017 and 2018, a study comparing four near-isogenic lines across multiple Tennessee locations was performed to identify agronomic traits associated with mutations in FAD3A and FAD3C loci, while holding FAD2-1A and FAD2-1B constant in the mutant (high oleic) state. Soybean lines were assessed for yield and oil quality based on mutations at FAD2-1 and FAD3 loci. Variations of wild-type and mutant genotypes were compared at FAD3A and FAD3C loci. Analysis using a generalized linear mixed model in SAS 9.4, indicated no yield drag or other negative agronomic traits associated with the high oleic and low linolenic acid genotype. All four mutations of fad2-1A, fad2-1B, fad3A, and fad3C were determined as necessary to produce a soybean with the new industry standard (>750 g kg−1 oleic and <30 g kg−1 linolenic acid) in a maturity group-IV-Late cultivar for Tennessee growers.  相似文献   
2.
Two studies examine complementarity (vs. mimicry) of dominant and submissive nonverbal behaviors. In the first study, participants interacted with a confederate who displayed either dominance (through postural expansion) or submission (through postural constriction). On average, participants exposed to a dominant confederate decreased their postural stance, whereas participants exposed to a submissive confederate increased their stance. Further, participants with complementing responses (dominance in response to submission and submission in response to dominance) liked their partner more and were more comfortable than those who mimicked. In the second study, complementarity and mimicry were manipulated, and complementarity resulted in more liking and comfort than mimicry. The findings speak to the likelihood of hierarchical differentiation (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
4.
Aqueous extracts of the coralline red algaeBossiella orbigniana have been shown to catalyze the enzymatic oxidation of arachidonic acid to a previously unreported ω6 eicosapentaenoic acid product. This unique fatty acid contains a conjugated tetraene with absorption maxima at 293, 306, and 321 nm, and was identified by spectral methods as 5(Z),8(Z),10(E),12(E),14(Z)-eicosapentaenoic acid. The compound was given the trivial name bosseopentaenoic acid. Under experimental conditions, production of bosseopentaenoic acid was linear up to 2 hr and dioxygen was consumed. Bosseopentaenoic acid, along with several other conjugated tetraenes, was also present in the algae endogenously as revealed by a comparison of the ultraviolet (UV) spectra and the high-performance liquid chromatographic (HPLC) pattern of the purified product and the organic extract ofBossiella.  相似文献   
5.
Self-report data were obtained from a middle-income sample of first-time mothers during pregnancy and at 1 and 3 months postpartum, and behavioral interactions between the mother and her infant were observed at 3 days and 1, 3, and 16 months postpartum. The main analyses revealed that pregnancy and postpartum mood states together explain a high proportion of the variance in mothers' maternal attitudes during the postpartum, although postpartum mood has the greater predictive power. Additionally, prior experience with children is significantly associated with maternal attitudes at all time points. Moreover, at both 1 and 3 months postpartum, depressed mothers, relative to nondepressed mothers, exhibit fewer affectionate contact behaviors toward their infants and are less likely to respond to infant vocalizations by vocalizing themselves, and, at 3 months, a higher proportion of the depressed mothers had started bottle-feeding their infants. Finally, differences in maternal behavior between depressed and nondepressed mothers during the early postpartum period were no longer apparent at 16 months postpartum. The implications of these findings are discussed with particular reference to the interrelations between prior child-care experience, mood, and maternal responsiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
6.
Theorists have predicted that repetition blindness (RB) should be absent for nonwords because they do not activate preexisting mental types. The authors hypothesized that RB would be observed for nonwords because RB can occur at a sublexical level. Four experiments showed that RB is observed for word-nonword pairs (noon noof), orthographically similar nonwords (glome glame), and identical repetitions (plass plass). More RB was found for words than for nonwords. Prior researchers may have failed to find RB for nonwords because display conditions that allow 2 words to be reliably encoded are insufficient for nonwords, or because observers coped with low ability to encode nonwords by using guessing strategies that do not require creating a mental type or tokenizing it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
7.
The ideology of fatherhood, as it is defined in Western, industrialized culture, assumes that fathers are biologically predisposed to be relatively uninvolved in infant care. This article summarizes recent revisions of both primate research and sociobiological theory. These new perspectives on male parenting behavior shift the focus from a narrow emphasis on the genetic relationship between male primates and their offspring to a broader focus that includes multiple social, demographic, and ecological variables. This paradigm underlines the behavioral flexibility, rather than the behavioral fixity, of male parenting behaviors. The relevance of this new theoretical consensus for social policy that could strengthen fathers' relationships with their children is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
8.
Job postings and the decision to interview: A verbal protocol analysis.   总被引:1,自引:0,他引:1  
Investigated the process of deciding whether or not to apply for jobs, using the verbal protocol analysis (VPA) technique. Verbal reports provided by participants as they evaluated job postings and decided whether or not to interview for jobs were analyzed to assess what information was heeded, the impact of incomplete or unusual information, and the role of inferences regarding job characteristics and probability of hire. Results indicated that location and compensation received the most attention and that participants also responded to the amount of information provided. In addition, participants made inferences about unobserved characteristics and probability of hire, although the latter played little role in the decision to interview. The study also provided support for the usefulness of VPA by demonstrating that neither the verbal protocol process nor the use of prompts significantly influenced participants' decisions (as compared with the decisions of control groups). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
Examined the differential prevalence of 10 major dimensions of psychotic and affective signs (e.g., auditory hallucinations, delusions of control, excitement/agitation, catatonic and bizarre behavior) and symptoms in 18 neuropsychologically impaired and 30 neuropsychologically intact schizophrenics who were diagnosed under Research Diagnostic Criteria. Assessments were based on the Present State Examination and on the Luria-Nebraska Neuropsychological Battery. Results show that the neuropsychologically impaired Ss had a lower incidence of delusions of reference and persecution and a diminished capacity for insight compared to neuropsychologically unimpaired Ss. Findings are discussed in terms of a frontal lobe dysfunction hypothesis of schizophrenic psychopathology. (3 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
10.
Abstract— A preferred method for determining the grating modulation of a rear‐projection display using a grating image and Fourier analysis is prescribed. This method is insensitive to spatial image noise and is in better correspondence with the response of the human visual system than is the standard technique. This method is not limited to rear‐projection displays and can be applied to any display technology.  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