全文获取类型
收费全文 | 1629篇 |
免费 | 32篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 23篇 |
化学工业 | 377篇 |
金属工艺 | 24篇 |
机械仪表 | 30篇 |
建筑科学 | 59篇 |
矿业工程 | 8篇 |
能源动力 | 21篇 |
轻工业 | 120篇 |
水利工程 | 7篇 |
石油天然气 | 5篇 |
无线电 | 91篇 |
一般工业技术 | 191篇 |
冶金工业 | 479篇 |
原子能技术 | 28篇 |
自动化技术 | 200篇 |
出版年
2022年 | 14篇 |
2021年 | 26篇 |
2017年 | 16篇 |
2016年 | 24篇 |
2014年 | 25篇 |
2013年 | 99篇 |
2012年 | 25篇 |
2011年 | 49篇 |
2010年 | 33篇 |
2009年 | 44篇 |
2008年 | 53篇 |
2007年 | 55篇 |
2006年 | 44篇 |
2005年 | 36篇 |
2004年 | 39篇 |
2003年 | 33篇 |
2002年 | 35篇 |
2001年 | 20篇 |
2000年 | 24篇 |
1999年 | 22篇 |
1998年 | 27篇 |
1997年 | 19篇 |
1996年 | 28篇 |
1995年 | 20篇 |
1994年 | 22篇 |
1993年 | 27篇 |
1992年 | 25篇 |
1991年 | 17篇 |
1990年 | 30篇 |
1989年 | 26篇 |
1988年 | 24篇 |
1987年 | 28篇 |
1986年 | 28篇 |
1985年 | 38篇 |
1984年 | 30篇 |
1983年 | 26篇 |
1982年 | 33篇 |
1981年 | 17篇 |
1980年 | 15篇 |
1979年 | 30篇 |
1978年 | 28篇 |
1977年 | 27篇 |
1976年 | 30篇 |
1975年 | 20篇 |
1974年 | 25篇 |
1973年 | 34篇 |
1972年 | 20篇 |
1970年 | 16篇 |
1969年 | 14篇 |
1958年 | 14篇 |
排序方式: 共有1663条查询结果,搜索用时 15 毫秒
81.
82.
Does producing a word slow performance of a concurrent, unrelated task? In 2 experiments, 108 participants named pictures and discriminated tones. In Experiment 1, pictures were named after cloze sentences; the durations of the word-production stages of lemma and phonological word-form selection were manipulated with high- and low-constraint cloze sentences and high- and low-frequency-name pictures, respectively. In Experiment 2, pictures were presented with simultaneous distractor words; the durations of lemma and phoneme selection were manipulated with conceptually and phonologically related distractors. All manipulations, except the phoneme-selection manipulation, delayed tone-discrimination responses as much as picture-naming responses. These results suggest that early word-production stages-lemma and phonological word-form selection-are subject to a central processing bottleneck, whereas the later stage-phoneme selection-is not. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
83.
van Schie Hein T.; van Waterschoot Boris M.; Bekkering Harold 《Canadian Metallurgical Quarterly》2008,34(6):1493
A robust finding in imitation literature is that people perform their actions more readily if they are congruent with the behavior of another person. These action congruency effects are typically explained by the idea that the observation of someone else acting automatically activates our motor system in a directly matching way. In the present study action congruency effects were investigated between an imitation task and a complementary action task. Subjects imitated or complemented a virtual actor's grasp on a manipulandum. In both tasks, a color-cue could be presented forcing subjects to ignore the task rule and execute a predefined grasp. Reaction times revealed a reversal of congruency effects in the complementary action task, suggesting that subjects were able to circumvent the automatic tendency to copy actions or postures of another person. In 2 additional control experiments, congruency effects were replicated, and a Simon effect was identified to underlie faster responses in the imitation task. These results make a case against current theoretical views on imitation and direct matching in favor of more flexible models of perception-action coupling. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
84.
The authors recruited 99 injection drug users to assess the psychometric properties of a new self-report questionnaire--the Harm Reduction Self-Efficacy Questionnaire (HRSEQ)--designed to measure injection drug users' confidence to employ 15 specific health-preserving coping skills in different types of high-risk situations (experiencing withdrawal, feeling depressed, and feeling social pressure to use drugs unsafely). Scores for each high-risk situation had good internal consistency (αs = .89 -.92) and good 1-week test-retest reliability (rs = .70 -.85). Comparison with measures of drug-related problems, use of coping skills, and health self-efficacy supported both construct and discriminant validity of the HRSEQ. Exploratory factor analyses revealed 3 major themes (cleanliness precautions, overdose precautions, and safer injection practices) that summarized most, but not all, of the 15 items. Mean differences among the 3 situations suggest that harm reduction self-efficacy should be assessed in the context of specific high-risk situations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
Comments on the article by W. Wilkins (see record 1986-25162-001) on placebo problems in psychotherapy research and suggests a refinement of efficacy research strategies that will allow such comparisons while relinquishing the use of a placebo construct. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
86.
Whole grain rice is rich in phenolic compounds. The effect of γ-irradiation on the main phenolic compounds in the rice grains of three genotypes (black, red, and white) was investigated. Three phenolic acids (p-coumaric acid, ferulic acid, and sinapinic acid) were identified as major phenolic compounds in all rice samples, while two anthocyanins (cyanidin-3-glucoside and peonidin-3-glucoside) were identified in pigmented grain samples. In general, γ-irradiation at most of doses could significantly (p < 0.05) decrease total phenolic acid contents in all samples and total anthocyanins contents in the black rice, but their decreases were not completely in a dose-dependent manner. Unexpectedly, 6 and 8 kGy significantly (p < 0.05) increased total contents of anthocyanins and phenolic acids in black rice. This study suggested that suitable doses of irradiation might be carefully selected and used to minimise the loss of antioxidant phenolic compounds in whole grain rice during storage. 相似文献
87.
Responds to Milden's comments (see record 2007-10564-001). In her response to my review (see record 2003-05429-013) of Lerner's The Dance of Anger: A Woman's Guide to Changing the Patterns of Intimate Relationships (see record 2006-00700-000), Dr. Milden assumes that I believe that there is no legitimate place for popular presentation of psychological knowledge and that feminist psychoanalytic writings do not represent a serious or thoughtful body of work. Quite the contrary. Although I did not expect The Dance of Anger to be a heavyweight, theoretical treatise, I did expect from someone of Lerner's stature at least a serious-popular book. What she has given us is "kitsch." This remains paradoxical, for as Milden points out, Lerner has written serious and scholarly works on the subject. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
88.
To test the stability of intergranular amorphous films against crystallization, a model experiment was conducted wherein a thin SiO2 film was deposited on a single-crystal TiO2 substrate, annealed to form a eutectic liquid in equilibrium with the substrate, then quenched and crystallized below the eutectic temperature. This geometry is free of residual stresses and capillary effects proposed by others as kinetic limitations to complete crystallization. Furthermore, using a binary system removes solute rejection barriers to complete crystallization. A remnant amorphous film ∼1.5 nm thick retained at the hetero-interface shows unequivocally that the amorphous film is thermodynamically preferred to a crystal/crystal interface in this system. 相似文献
89.
Harold Margolin Zhirui Wang Tzi-Kang Chen 《Metallurgical and Materials Transactions A》1986,17(1):107-114
Evidence for elastic interactions is reviewed, and it is concluded that elastic assistance to yielding must be taken into
account in an equation for the relationship between yield stress σy and grain size,d. The equation which is proposed is generalized from observation on bicrystal behavior and is σy=σ0+K1d-1/2-K2[1-(d/DL)m][(d/Ds)n-1] σ0 corresponds to the stress at which the second and third terms are equal; K1 is similar to the Hall-Petch constant, but is lower in magnitude; K2 is a constant which depends on the average difference in the matrix of elastic constants between adjacent grains and on grain
shape.D
L andD
s are the upper and lower grain size limits over which elastic interaction takes place, and the third term is zero ford = D
L ord = D
s. The constantsm andn define, respectively, the limit of the grain over which elastic interaction takes place and the fraction of the grain contributing
elastic interaction to the surrounding grains. In effect, [1 - (d/D
L)m][d/D
s)n -1] constitutes the volume fraction of the grain boundary region over which elastic interaction assists slip. The equation,
with different values of the constants, has been shown to fit σy
— d
-1/2 data over a wide range of grain sizes for Ni,22 Zn,23 and modified 1010 steel.24 Volume fraction of grain boundary deformation zone data for β-Ti-Mn8 are shown to fit predictions as well. The constants σ0,K
1 DL, Ds, m, andn can all be determined experimentally, thus leading to a determination ofK
2z. 相似文献
90.
Barry M. Verdegan James G. Draxler Harold W. Fenrick 《Particulate Science and Technology》1985,3(3):115-126
Contrary to earlier thought, recent studies have shown that particle electrophoretic mobility in nonpolar liquids is dependent on field strength at high fields. This study provides independent confirmation using a cross-flow electrofiltration technique and explores possible explanations for the phenomena. Experimental work was conducted using kaolin/Mi1-H-5606A petroleum oil systems with various concentrations of ionic additive. Electrophoretic mobility at different field strengths and additive concentrations were determined. It was found that mobility is independent of field strength at low and high fields but varies with field strength at intermediate fields. This dependence is explained on the basis of the relaxation effect and partial detachment of the diffuse double layer from the particle. In the field dependent region the mobility change with respect to field Increases with increasing surface charge and electrical double layer thickness. At high fields the double layer completely detaches and mobility behaves independently of field strength. Prior exposure of the particle to high fields appeared to temporarily increase mobility. This may be the result of selective deposition of low mobility particles and Increased particle charge due to field charge exchange or contact charging. Under the conditions of this study double layer detachment appeared to be the major source of field dependent behavior. 相似文献