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   1872篇
  免费   111篇
  国内免费   2篇
电工技术   12篇
综合类   3篇
化学工业   598篇
金属工艺   23篇
机械仪表   31篇
建筑科学   91篇
矿业工程   2篇
能源动力   20篇
轻工业   335篇
水利工程   23篇
石油天然气   4篇
无线电   73篇
一般工业技术   305篇
冶金工业   267篇
原子能技术   6篇
自动化技术   192篇
  2024年   4篇
  2023年   22篇
  2022年   110篇
  2021年   129篇
  2020年   44篇
  2019年   56篇
  2018年   61篇
  2017年   48篇
  2016年   48篇
  2015年   46篇
  2014年   72篇
  2013年   125篇
  2012年   108篇
  2011年   140篇
  2010年   102篇
  2009年   100篇
  2008年   107篇
  2007年   88篇
  2006年   80篇
  2005年   67篇
  2004年   60篇
  2003年   48篇
  2002年   46篇
  2001年   23篇
  2000年   21篇
  1999年   22篇
  1998年   14篇
  1997年   26篇
  1996年   17篇
  1995年   13篇
  1994年   13篇
  1993年   17篇
  1992年   7篇
  1991年   8篇
  1990年   10篇
  1989年   11篇
  1988年   10篇
  1987年   12篇
  1986年   8篇
  1985年   13篇
  1983年   8篇
  1982年   3篇
  1980年   4篇
  1978年   3篇
  1977年   2篇
  1975年   1篇
  1974年   3篇
  1973年   1篇
  1972年   1篇
  1965年   1篇
排序方式: 共有1985条查询结果,搜索用时 15 毫秒
1.
Currently, ethnic and racial minority individuals represent a large proportion of the U.S. population, and researchers expect that they will represent the majority of the population by 2050. This shift in U.S. demographics calls for a greater awareness and integration of cultural issues into the assessment and treatment of ethnically and linguistically diverse clients. This article examines the unique beliefs and manifestations of illnesses among Haitians in connection with the American Psychological Association's (APA, 2002) Multicultural Guidelines. The authors use a common culture-bound syndrome, Séizisman, to illustrate the cultural beliefs, assessment, and treatment of illnesses among Haitians. In so doing, they demonstrate how to incorporate the APA Multicultural Guidelines into treatment with clients of diverse cultural and racial backgrounds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
2.
The experiments of M. Carey Lea (1823-1897) are usually considered the first systematic investigations on the chemical effects of mechanical action. This paper collects the most important facts about Lea's life and discusses his research from the point of view of mechanochemistry. Lea was born into a family of considerable privilege and exceptional achievements. He suffered from weak health throughout his life. Consequently, he was educated at home by a tutor and later worked in the private laboratory of his home in Philadelphia. Lea was primarily a photochemist, his first mechanochemical observation in 1866 concerned the pressure sensitivity of photographic plates. Later in his life, he investigated the effect of various kinds of energy—heat, light, mechanical action—on allotropic (colloidal) silver and silver halides. The “parallelism” of the results motivated Lea to study the mechanochemical decomposition of dozens of stable compounds between 1892 and 1894. He observed the decomposition of silver and mercuric chlorides by trituration in a mortar, although the same compounds are known to melt or sublime undecomposed when heated. Lea was elected member of the National Academy of Sciences in 1892.  相似文献   
3.
4.
汽车中出现的电子设备和系统越来越多,而它们也是汽车功能创新的驱动力. 汽车厂商正在越来越多地使用电子系统和半导体集成电路用于汽车的各种应用,包括驾驶员信息和通信、车内娱乐电子设备、传动系和身体控制电子设备以及汽车安全和舒适设备.  相似文献   
5.
Modafinil is indicated for the management of excessive daytime sleepiness; however, recent studies have examined a broad range of potential uses. Given that clinical uses of modafinil may be expanding, this study compared modafinil and d-amphetamine effects on subjective and performance measures. Across 11 sessions, 11 healthy adults were tested after oral doses of placebo (5 sessions), modafinil (1.75 mg/kg, 3.50 mg/kg, or 7.00 mg/kg), and d-amphetamine (0.035 mg/kg, 0.070 mg/kg, 0.140 mg/kg) under double-blind, randomized conditions. Assessments of cognitive performance and subjective effects were completed before drug administration, 30 min after drug administration, and at hourly intervals after drug administration for 5 hr. Modafinil increased ratings on the Amphetamine and Morphine Benzedrine Group scales of the Addiction Research Center Inventory (ARCI) and increased ratings on the Vigor and Total Positive scales of the Profile of Mood States. d-Amphetamine increased visual analog ratings of feeling stimulated and liking the drug and increased ratings on the Morphine Benzedrine Group scale of the ARCI. Both medications significantly reduced visual analog scale ratings of feeling sleepy, and modafinil decreased ratings on the ARCI Pentobarbital-Chlorpromazine-Alcohol Group scale. Both medications sustained performance that deteriorated across time on the Sternberg Number Recognition Test. Modafinil also enhanced performance rate on the Digit-Symbol Substitution Task above baseline levels and increased response rate on the Repeated Acquisition of Response Sequences Task. These results suggest that modafinil engenders alerting effects and increases performance in healthy non-sleep-deprived individuals comparable with that of d-amphetamine. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
6.
Understanding how aging influences cognition across different cultures has been hindered by a lack of standardized, cross-referenced verbal stimuli. This study introduces a database of such item-level stimuli for both younger and older adults, in China and the United States, and makes 3 distinct contributions. First, the authors specify which item categories generalize across age and/or cultural groups, rigorously quantifying differences among them. Second, they introduce novel, powerful methods to measure between-group differences in freely generated ranked data, the rank-ordered logit model and Hellinger Affinity. Finally, a broad archive of tested, cross-linguistic stimuli is now freely available to researchers: data, similarity measures, and all stimulus materials for 105 categories and 4 culture-by-age groups, comprising over 10,000 fully translated unique item responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
7.
High-resolution two-dimensional (2-D) polyacrylamide gel electrophoresis allows the separation of complex biological mixtures (i.e., several hundred proteins from a bacterial cell lysate) in a single experiment. In this report proteins from Haemophilus influenzae were separated by 2-D gels and analyzed by peptide mass fingerprinting and/or amino acid analysis. By comparing the peptide mass profiles and the amino acid composition with the Haemophilus influenzae database, 119 protein spots were identified. The combination of amino acid analysis and peptide mass fingerprinting is a powerful tool for a rapid and economical identification of a large number of proteins resolved by 2-D gels. Studies on gene regulation and changes of protein expression upon drug treatment require quick and serial analysis techniques to efficiently identify potential new drug targets.  相似文献   
8.
Examined the emotional similarity hypothesis, a derivation from social comparison theory, which predicts that increasing fear should lead to greater affiliation with someone who is awaiting the same threat (and who therefore is of relatively similar emotional status) relative to someone who has already experienced the threat (and who therefore is of relatively dissimilar emotional status). Results failed to support the emotional similarity hypothesis and in so doing challenged the importance of emotional comparison as a determinant of verbal affiliation under threat. Cognitive clarity concerns instead seemed to account better for the observed effects on verbal affiliation. Supplementary analyses of nonverbal affiliation (facial glances) likewise ran counter to an emotional similarity prediction. Effects of affiliation on anxiety were also examined. Previous conclusions regarding the pattern and causes of affiliation under threat that have relied on the affiliate-choice paradigm are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
The ab-initio crystal structure solution by powder diffraction data requires great efforts because of the collapse of the experimental information onto the one dimensional 2θ axis of the pattern. Different strategies will be described aiming at improving the process of extraction of the integrated intensities from the experimental pattern in order to make more straightforward the structure solution process by direct methods. Particular attention will be devoted to the EXPO program. Some of its performance will be analysed and results will be shown.  相似文献   
10.
Social and emotional competence were evaluated using self-report and behavioral measures in adults with attention-deficit/hyperactivity disorder (ADHD) and controls. Adults with ADHD viewed themselves as less socially competent but more sensitive toward violations of social norms than controls. Films depicting emotional interactions were used to assess linguistic properties of free recall and perceived emotional intensity. Although adults with ADHD used more words to describe the scenes, they used fewer emotion-related words, despite rating the emotions depicted as more intense than did controls. In contrast, no group differences for words depicting social or cognitive processes were observed. Overall, adults with ADHD appear more aware of their problems in social versus emotional skills. Findings may have implications for improving the psychosocial functioning of these adults. (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