全文获取类型
收费全文 | 81555篇 |
免费 | 9058篇 |
国内免费 | 4758篇 |
专业分类
电工技术 | 9783篇 |
技术理论 | 3篇 |
综合类 | 7646篇 |
化学工业 | 5410篇 |
金属工艺 | 3668篇 |
机械仪表 | 6534篇 |
建筑科学 | 2521篇 |
矿业工程 | 2718篇 |
能源动力 | 1549篇 |
轻工业 | 6451篇 |
水利工程 | 1137篇 |
石油天然气 | 2708篇 |
武器工业 | 1333篇 |
无线电 | 16918篇 |
一般工业技术 | 6737篇 |
冶金工业 | 3256篇 |
原子能技术 | 690篇 |
自动化技术 | 16309篇 |
出版年
2024年 | 401篇 |
2023年 | 1123篇 |
2022年 | 1813篇 |
2021年 | 2275篇 |
2020年 | 2449篇 |
2019年 | 1911篇 |
2018年 | 1898篇 |
2017年 | 2497篇 |
2016年 | 2857篇 |
2015年 | 3330篇 |
2014年 | 4750篇 |
2013年 | 4623篇 |
2012年 | 5986篇 |
2011年 | 6411篇 |
2010年 | 4870篇 |
2009年 | 4789篇 |
2008年 | 4866篇 |
2007年 | 5897篇 |
2006年 | 5190篇 |
2005年 | 4380篇 |
2004年 | 3608篇 |
2003年 | 3270篇 |
2002年 | 2672篇 |
2001年 | 2216篇 |
2000年 | 1963篇 |
1999年 | 1540篇 |
1998年 | 1271篇 |
1997年 | 1103篇 |
1996年 | 973篇 |
1995年 | 782篇 |
1994年 | 720篇 |
1993年 | 565篇 |
1992年 | 433篇 |
1991年 | 376篇 |
1990年 | 308篇 |
1989年 | 260篇 |
1988年 | 188篇 |
1987年 | 116篇 |
1986年 | 93篇 |
1985年 | 100篇 |
1984年 | 83篇 |
1983年 | 86篇 |
1982年 | 71篇 |
1981年 | 49篇 |
1980年 | 42篇 |
1979年 | 37篇 |
1978年 | 20篇 |
1977年 | 26篇 |
1976年 | 12篇 |
1959年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
空调循环水系统中,多台水泵运行时多台同步变频调节和单台变频调节的比较 相似文献
992.
Emotional Stroop tasks (subliminal/supraliminal exposures), implicit memory tasks (tachistoscopic word identification), and explicit memory tasks (free recall after incidental learning) with 4 word types (physical threat, positive, negative, and neutral words) were administered to patients with major depressive disorder (n = 30), panic disorder (n = 33), somatoform disorder (n = 25), and healthy control participants (n = 33). On the Stroop task, panic patients showed subliminal interferences for physical threat and negative words, depressive patients showed supraliminal interferences for negative words, and somatoform patients showed supraliminal interferences for physical threat words. No patient groups demonstrated implicit memory biases. On the explicit memory task, depressive and panic patients showed memory biases for negative words; somatoform patients showed biases for physical threat words. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
993.
In the present study, the authors examined somatosensory processing in 30 biological relatives of persons with schizophrenia (hereafter called "schizophrenia relatives"), 30 biological relatives of persons with bipolar affective disorder (psychiatric family control subjects), and 30 healthy control subjects with no family history of psychopathology. All 3 groups completed a weight discrimination task, a 2-point discrimination task, and a complex cognitive somatosensory task (i.e., graphesthesia). The schizophrenia relatives performed significantly worse on all 3 somatosensory tasks compared with both the healthy control subjects and the bipolar relatives. The healthy control subjects and psychiatric family control subjects showed no significant differences on any of the somatosensory tasks. Within the weight discrimination and 2-point discrimination tasks, schizophrenia relatives showed group differences on the d' index, the measure of sensitivity, whereas all 3 groups did not differ on lnβ, the measure of response bias, suggesting a genuine difference in weight and touch sensitivity. The d' value of the weight discrimination task was significantly associated with both the cognitive-perceptual factor and negative symptom factor of the clinical questionnaire (e.g., Schizotypal Personality Questionnaire; SPQ), whereas the 2-point discrimination d' value and graphesthesia scores were significantly associated only with the cognitive-perceptual factor of the SPQ. Implications for the possible relation between somatosensory task performance and schizophrenia liability are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
994.
Takeshi Kubota 《国际钢铁研究》2005,76(6):464-470
Control of crystalline orientation and consequent enhancement of magnetic properties are important for decreasing core loss of non‐oriented silicon steel as well as grain‐oriented silicon steel. Through the development of special process techniques to produce clean refined steel, it is now possible to use any element to improve the crystalline texture control of steel without producing harmful effects. Utilization of these effects have actually lowered the core loss and raised the magnetic flux density of the products, and a product series of high‐efficiency non‐oriented silicon steel has been developed. Recently, demand has grown for non‐oriented silicon steel with particular properties, such as lower core loss at high frequencies or high strength, as high‐speed motors have progressed in regard to high efficiency and miniaturization. In response to this trend, non‐oriented thin gauge silicon steel with a thickness of 0.20 and 0.15mm and high strength non‐oriented thin gauge silicon steel with the same thickness but a yield strength of more than 570MPa and 780MPa have been developed. 相似文献
995.
Missirlian Tanya M.; Toukmanian Shaké G.; Warwar Serine H.; Greenberg Leslie S. 《Canadian Metallurgical Quarterly》2005,73(5):861
Early-, middle-, and late-phase client emotional arousal, perceptual processing strategies, and working alliance were examined in relation to treatment outcome on 4 measures in 32 clients who previously underwent experiential therapy for depression. Hierarchical regression analyses relating these variables to outcome indicated that results varied depending on the therapeutic process, phase of treatment, and outcome measure involved in the analyses. Mid-therapy arousal predicted improvements in self-esteem, whereas mid- and late treatment perceptual processing predicted reductions in client interpersonal dysfunction. Emotional arousal in conjunction with perceptual processing during mid-therapy predicted reductions in depressive and psychopathological symptomatology better than either of these variables alone. The implications of these findings for psychotherapy research and practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
996.
Wetter Spencer; Peavy Guerry; Jacobson Mark; Hamilton Joanne; Salmon David; Murphy Claire 《Canadian Metallurgical Quarterly》2005,19(4):428
The influence of Huntington's disease (HD) on the olfactory event-related potential (OERP), an electrophysiological measure of olfactory information processing, has not been reported to date. In the present study, olfactory and auditory event-related potentials (ERPs) were recorded monopolarly from Fz, Cz, and Pz electrode sites in 8 patients with HD and 8 age- and gender-matched control participants. Results demonstrated that individuals with HD were delayed compared with controls on the P3 component of the OERP (p 相似文献
997.
Wilk Christopher M.; Gold James M.; McMahon Robert P.; Humber Katherine; Iannone Virginia N.; Buchanan Robert W. 《Canadian Metallurgical Quarterly》2005,19(6):778
Cognitive impairment is well documented in schizophrenia, though some reports have been interpreted to suggest that it is possible to have schizophrenia without neuropsychological impairment. The authors tested this by comparing the neuropsychological profiles of closely matched patients with schizophrenia and healthy comparison participants. Sixty-four patients with schizophrenia and 64 healthy comparison cases, matched to within 3 Full-Scale IQ points, were tested using the Wechsler Adult Intelligence Scale (3rd ed.; D. Wechsler, 1997b) and the Wechsler Memory Scale (3rd ed.; D. Wechsler, 1997c). Neuropsychological profiles for these groups were markedly different, with the group of patients with schizophrenia exhibiting performance deficits in memory and speeded visual processing but superior verbal comprehension and perceptual organization relative to the group of healthy comparison participants matched on Full-Scale IQ. Thus, scoring in the normal range does not preclude neuropsychological abnormality in schizophrenia, confirming that neuropsychological impairment is a core feature of the illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
998.
MacDonald Angus W. III; Goghari Vina M.; Hicks Brian M.; Flory Janine D.; Carter Cameron S.; Manuck Stephen B. 《Canadian Metallurgical Quarterly》2005,19(6):814
Convergent and divergent validity are critically important in developing psychological measures that reveal interpretable deficits in disordered populations. This article reports on 2 studies that evaluated the validity of context processing measures. In Experiment 1, a confirmatory factor analysis of data from 481 healthy adults established the convergent validity of 2 context processing measures and showed that context processing accounted for significant amounts of variance in standard IQ and working memory measures. In Experiment 2, 20 schizophrenia patients, 16 of their healthy siblings, and 28 controls were evaluated using a novel, short context processing measure, the dot pattern expectancy (DPX) task. The DPX was sensitive to specific deficits in schizophrenia patients and their healthy siblings. These findings support the construct validity of context processing measures, suggest context processing is a component of intellectual functioning, and demonstrate that brief context processing measures remain sensitive to psychopathological deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
999.
Ferrer Emilio; Salthouse Timothy A.; McArdle John J.; Stewart Walter F.; Schwartz Brian S. 《Canadian Metallurgical Quarterly》2005,20(3):412
Longitudinal multivariate mixed models were used to examine the correlates of change between memory and processing speed and the contribution of age and retest to such change correlates. Various age- and occasion-mixed models were fitted to 2 longitudinal data sets of adult individuals (N > 1,200). For both data sets, the results indicated that the correlation between the age slopes of memory and processing speed decreased when retest effects were included in the model. If retest effects existed in the data but were not modeled, the correlation between the age slopes was positively biased. The authors suggest that although the changes in memory and processing speed may be correlated over time, age alone does not capture such a covariation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
1000.
Yamashita Jill A.; Hardy Joseph L.; De Valois Karen K.; Webster Michael A. 《Canadian Metallurgical Quarterly》2005,31(3):420
Viewing a distorted face induces large aftereffects in the appearance of an undistorted face. The authors examined the processes underlying this adaptation by comparing how selective the aftereffects are for different dimensions of the images including size, spatial frequency content, contrast, and color. Face aftereffects had weaker selectivity for changes in the size, contrast, or color of the images and stronger selectivity for changes in contrast polarity or spatial frequency. This pattern could arise if the adaptation is contingent on the perceived similarity of the stimuli as faces. Consistent with this, changing contrast polarity or spatial frequency had larger effects on the perceived identity of a face, and aftereffects were also selective for different individual faces. These results suggest that part of the sensitivity changes underlying the adaptation may arise at visual levels closely associated with the representation of faces. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献