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   2148篇
  免费   65篇
  国内免费   1篇
电工技术   10篇
综合类   11篇
化学工业   485篇
金属工艺   19篇
机械仪表   40篇
建筑科学   98篇
矿业工程   34篇
能源动力   56篇
轻工业   251篇
水利工程   16篇
石油天然气   12篇
无线电   78篇
一般工业技术   281篇
冶金工业   615篇
原子能技术   4篇
自动化技术   204篇
  2022年   23篇
  2021年   61篇
  2020年   26篇
  2019年   30篇
  2018年   40篇
  2017年   32篇
  2016年   50篇
  2015年   21篇
  2014年   50篇
  2013年   157篇
  2012年   71篇
  2011年   94篇
  2010年   84篇
  2009年   62篇
  2008年   77篇
  2007年   72篇
  2006年   79篇
  2005年   59篇
  2004年   41篇
  2003年   71篇
  2002年   53篇
  2001年   35篇
  2000年   45篇
  1999年   47篇
  1998年   74篇
  1997年   70篇
  1996年   49篇
  1995年   43篇
  1994年   48篇
  1993年   43篇
  1992年   31篇
  1990年   14篇
  1989年   26篇
  1988年   28篇
  1987年   15篇
  1986年   15篇
  1985年   25篇
  1984年   31篇
  1983年   23篇
  1982年   18篇
  1981年   14篇
  1980年   14篇
  1979年   16篇
  1978年   20篇
  1977年   13篇
  1976年   33篇
  1974年   14篇
  1973年   14篇
  1970年   13篇
  1969年   13篇
排序方式: 共有2214条查询结果,搜索用时 390 毫秒
11.
D. P. O'Brien et al (see record 1995-08272-001) argue that the mental model theory of propositional reasoning is easy to refute, and they report 3 experiments that they believe falsify the theory. In contrast, L. Bonatti (see record 1995-08253-001) argues that the model theory is too flexible to be falsified. It is shown that the experiments by O'Brien et al do not refute the model theory and that Bonatti's claims are ill founded. Formal rule theories of propositional reasoning have 3 major weaknesses in comparison with the model theory: (1) They have no decision procedure; (2) they lack predictive power, providing no account of several robust phenomena (e.g., erroneous conclusions tend to be consistent with the premises); and (3) as a class of theories, they are difficult to refute experimentally. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
12.
Adult and adolescent Ss were asked to list possible consequences of either accepting or declining opportunities to engage in various potentially risky behaviors (e.g., drinking and driving, skipping school to go to a mall). Response patterns were quite similar for these adults and adolescents, indicating shared beliefs about the possibilities. Although taking and avoiding a risk are logically complementary actions, they did not prove to be psychologically complementary. Other comparisons showed systematic differences in the consequences produced for 1-time and regular (or repeated) versions of the same behaviors, as well as open-ended and closed-ended response modes. These results are discussed in terms of their methodological implications for studying risk perceptions, their practical implications for influencing adolescents' risk behaviors, and their theoretical implications for understanding intellectual development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
13.
Multiple forms of a symbol-digit substitution task were used to provide a componential analysis of age differences in coding task performance. The results demonstrated age differences in feature encoding, memory, and visual search. A 2nd experiment was conducted with young adults to investigate a sensory deficit as a locus of age differences. The spatial contrast sensitivity deficit of older adults was simulated on forms by applying a digital filter. Persons in the age-simulated contrast condition performed worse than those in the normal contrast condition. The stimulus degradation effect was linked to visual search speed. The study illustrates the utility of componential analysis and offers direct support for the hypothesis that sensory deficits affect performance on tasks used to assess intelligence (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
14.
The effectiveness of overlearning in enhancing performance has been acknowledged by researchers within the training community for years. In spite of this general consensus, the empirical basis for this claim is often not clear. This article presents a meta-analysis of the effects of overlearning on retention. Results indicate that overlearning produces a significant effect on retention of moderate overall magnitude and that the effect of overlearning on retention is moderated by the degree of overlearning, type of task, and length of retention period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
15.
Expanded on R. E. Fassinger's (see record 1990-21225-001) model of career choice in college women by testing 2 causal models of career choice and orientation with high school women. Ss were 409 adolescent women enrolled in their last year of high school in an all-female private liberal arts high school in a large Midwestern city. Structural equation modeling analyses suggested that the career orientation and career choice of adolescent women were predicted by ability, agentic characteristics, gender role attitudes, and relationship with mother. Young women who possessed liberal gender role attitudes, were instrumental and efficacious with regard to math and careers, and exhibited moderate degrees of attachment and independence from their mothers tended to value their career pursuits. Adolescent women who selected nontraditional and prestigious careers showed high ability and strong agentic characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
16.
The ability of several variables to distinguish unipolar deflections due to local activation from those due to nonlocal activity is studied. A model of polyphasic deflections based on atrial recordings during reentrant tachycardia was used to facilitate distinction of local and distant activity by methods independent of the test variables. The performances of variables were assessed by comparing areas under receiver operating characteristic curves. Optimal thresholds of test variables were identified by maximizing statistics which corrected for the pretest probability of local activation. It was found that the greatest negative first derivative of the unipolar potential discriminated between local and distant ventricular signals, but performed less well than the ratio of the first derivative to the potential for distinguishing between local atrial signals and distant ventricular signals. A linear combination of the potential and the ratio of the first derivative and the potential performed well for all groups of signals studied. Optimal criteria for detecting local activation are discussed  相似文献   
17.
More than half of all U.S. infants and toddlers spend at least 20 hr per week in the care of a nonparent adult. This article uses survival analysis to identify which families are most likely to place their child in care and the ages when these choices are made, using data from a national probability sample of 2,614 households. Median age at first placement is 33 months, but age varies by geographic region, mother's employment status during pregnancy, mother's education level, and family structure (1 vs. 2 parents, mother's age at 1st birth, and number of siblings). Controlling for these effects, differences by race and ethnicity are small. Implications for studies of child-care selection and evaluations of early childhood programs are discussed.  相似文献   
18.
Partial evaluation is a symbolic manipulation technique used to produce efficient algorithms when part of the input to the algorithm is known. Other applications of partial evaluators such as universal compilation and compiler generation are also known to be possible. A partial evaluator receives as input a program and partially known input to that program, and outputs a residual program which should run at least as efficient as the input program with restricted input. In this paper we study the case where both the input and residual programs are logic programs, being the partial evaluator itself a logic program. Up to now, partial evaluators have failed to process large “non=toy” examples. Here we present extensions to partial evaluators whic will allow us to produce more efficient residual programs using less computing resources, during partial evaluation. First, the introduced extensions allow the processing of large examples, which is not possible with the previous techniques. This is now possible since the extensions use less CPU time and memory consumption during the partial evaluation process. Second, the extended partial evaluator produces smaller residual programs, producing important CPU time optimizing effects. With the standard techniques, a partial evaluator will most probably act as a pessimizer, not as an optimizer. Examples are given.  相似文献   
19.
Journal of Logic, Language and Information - Despite the incremental nature of Dynamic Syntax (DS), the semantic grounding of it remains that of predicate logic, itself grounded in set theory, so...  相似文献   
20.

Fall und Kommentare

Sch?n warm zudecken ...  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