全文获取类型
收费全文 | 4101篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 10篇 |
综合类 | 2篇 |
化学工业 | 254篇 |
金属工艺 | 11篇 |
机械仪表 | 23篇 |
建筑科学 | 36篇 |
能源动力 | 16篇 |
轻工业 | 68篇 |
水利工程 | 7篇 |
无线电 | 103篇 |
一般工业技术 | 118篇 |
冶金工业 | 3407篇 |
原子能技术 | 7篇 |
自动化技术 | 51篇 |
出版年
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2018年 | 4篇 |
2017年 | 11篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 32篇 |
2012年 | 16篇 |
2011年 | 23篇 |
2010年 | 22篇 |
2009年 | 23篇 |
2008年 | 37篇 |
2007年 | 48篇 |
2006年 | 37篇 |
2005年 | 48篇 |
2004年 | 30篇 |
2003年 | 27篇 |
2002年 | 25篇 |
2001年 | 20篇 |
2000年 | 26篇 |
1999年 | 125篇 |
1998年 | 1035篇 |
1997年 | 621篇 |
1996年 | 382篇 |
1995年 | 226篇 |
1994年 | 177篇 |
1993年 | 193篇 |
1992年 | 32篇 |
1991年 | 49篇 |
1990年 | 49篇 |
1989年 | 51篇 |
1988年 | 72篇 |
1987年 | 55篇 |
1986年 | 37篇 |
1985年 | 35篇 |
1984年 | 19篇 |
1983年 | 30篇 |
1982年 | 29篇 |
1981年 | 41篇 |
1980年 | 52篇 |
1979年 | 20篇 |
1978年 | 18篇 |
1977年 | 73篇 |
1976年 | 166篇 |
1975年 | 13篇 |
1974年 | 4篇 |
1973年 | 13篇 |
1971年 | 7篇 |
排序方式: 共有4113条查询结果,搜索用时 0 毫秒
101.
Generation is thought to enhance both item-specific and relational processing of generated targets as compared with read words (M. A. McDaniel & P. J. Waddill, 1990). Generation facilitates encoding of the cue-target relation and sometimes boosts encoding of relations across list items. Of interest is whether generation can also increase the encoding of target-location associations. Because the literature on this point is mixed, 3 procedural differences between 2 studies (E. J. Marsh, G. Edelman, & G. H. Bower, 2001; N. W. Mulligan, 2004) were identified and manipulated. A positive generation effect was found for location memory, but this effect was reduced when subjects wrote down the study words and when the filler task involved generation. Generation can enhance location memory in addition to item memory but only if the experimental parameters do not interfere with the processing benefits of generation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
102.
The internal/external frame of reference (I/E) model explains a seemingly paradoxical pattern of relations between math and verbal self-concepts and corresponding measures of achievement, extends social comparison theory, and has important educational implications. In a cross-cultural study of nationally representative samples of 15-year-olds from 26 countries (total N = 55,577), I/E predictions were supported in that (a) math and verbal achievements were highly correlated, but math and verbal self-concepts were nearly uncorrelated; (b) math achievement had positive effects on math self-concept, but negative effects on verbal self-concept; and (c) verbal achievement had positive effects on verbal self-concept, but negative effects on math self-concept. Supporting the cross-cultural generalizability of predictions, multigroup structural equation models demonstrated good support for the generalizabilify of results across 26 countries participating in the Programme for International Student Assessment project sponsored by the Organisation for Economic Co-operation and Development. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
103.
Marsh Elizabeth J.; Dolan Patrick O.; Balota David A.; Roediger Henry L. 《Canadian Metallurgical Quarterly》2004,19(1):134
In 3 experiments, the authors examined part-set cuing effects in younger and older adults. Participants heard lists of category exemplars and later recalled them. Recall was uncued or cued with a subset of studied items. In Experiment 1, participants were cued with some of the category names, and they remembered fewer never-cued categories than a free-recall condition. In Experiment 2, a similar effect was observed for category exemplar cues. There was also an age difference: By some measures, a small number of cues impaired older adults more than younger. Experiment 3 replicated this result and found that older adults were disproportionately slow in the presence of cues. Across experiments, older adults showed robust part-set cuing effects, and sometimes, they were disproportionately impaired by cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
104.
Measurement of cell volume in living epithelial cells has become an important technique in studies of membrane transport processes that function in cell volume regulation. Planimetry of video images of optical sections enables the measurement of the cross sectional area of each section. Cell volume is calculated from the measured area of each section and the known focus displacements. In the past the measurement of cross section area has been done by manual positioning of a cursor superimposed on the video image. Each experiment generates approximately 200 images in which two or more cells may be analysed. We have developed a computer-based method that uses one image as a template, and allows automated area determination of successive images by template matching and digital image processing. This new method is comparable to the older method in speed and accuracy, but requires much less effort from the experimenter. 相似文献
105.
FC Sparks AG Wile KP Ramming HK Silver RW Wolk DL Morton 《Canadian Metallurgical Quarterly》1976,111(10):1057-1062
Antibody against a breast carcinoma antigen was present in patients with breast carcinoma and other cancer more often (P less than .05) than in normal women. The incidence of antibody in women with breast carcinoma correlated with the presence or absence of gross tumor, and the titer of antibody paralleled the clinical course. These results suggest importance of a host-immune response to breast carcinoma. Fifty-seven patients with stage II carcinoma of the breast were entered into a prospective randomized adjuvant chemoimmunotherapy program of cyclophosphamide, methotrexate, and fluorouracil, and BCG vaccine +/- an irradiated allogeneic tumor cell vaccine. After 24 months of study, metastases occurred in two patients (3.5%) and a new primary carcinoma developed in the contralateral breast in two others, for an overall treatment failure rate of 7%. Adjuvant chemoimmunotherapy can delay early recurrence. Long-term follow-up is needed to assess the significance of these results. 相似文献
106.
Marsh JW Bessa Y Birchall A Blanchardon E Hofmann W Nosske D Tomasek L 《Radiation protection dosimetry》2008,130(1):101-106
The European project Alpha-Risk aims to quantify the cancer and non-cancer risks associated with multiple chronic radiation exposures by epidemiological studies, organ dose calculation and risk assessment. In the framework of this project, mathematical models have been applied to the organ dosimetry of uranium miners who are internally exposed to radon and its progeny as well as to long-lived radionuclides present in the uranium ore. This paper describes the methodology and the dosimetric models used to calculate the absorbed doses to specific organs arising from exposure to radon and its progeny in the uranium mines. The results of dose calculations are also presented. 相似文献
107.
C. Hassel K. Blaum T. Day Goodacre H. Dorrer Ch. E. Düllmann K. Eberhardt S. Eliseev C. Enss P. Filianin A. Fäßler A. Fleischmann L. Gastaldo M. Goncharov D. Hengstler J. Jochum K. Johnston M. Keller S. Kempf T. Kieck U. Köster M. Krantz B. Marsh C. Mokry Yu. N. Novikov P. C. O. Ranitzsch S. Rothe A. Rischka J. Runke A. Saenz F. Schneider S. Scholl R. X. Schüssler F. Simkovic T. Stora P. Thörle-Pospiech A. Türler M. Veinhard M. Wegner K. Wendt K. Zuber 《Journal of Low Temperature Physics》2016,184(3-4):910-921
108.
109.
Otis Smart Douglas MausEric Marsh Dennis DlugosBrian Litt Kimford Meador 《Expert systems with applications》2012,39(8):7355-7370
Localizing an epileptic network is essential for guiding neurosurgery and antiepileptic medical devices as well as elucidating mechanisms that may explain seizure-generation and epilepsy. There is increasing evidence that pathological oscillations may be specific to diseased networks in patients with epilepsy and that these oscillations may be a key biomarker for generating and indentifying epileptic networks. We present a semi-automated method that detects, maps, and mines pathological gamma (30-100 Hz) oscillations (PGOs) in human epileptic brain to possibly localize epileptic networks. We apply the method to standard clinical iEEG (<100 Hz) with interictal PGOs and seizures from six patients with medically refractory epilepsy. We demonstrate that electrodes with consistent PGO discharges do not always coincide with clinically determined seizure onset zone (SOZ) electrodes but at times PGO-dense electrodes include secondary seizure-areas (SS) or even areas without seizures (NS). In 4/5 patients with epilepsy surgery, we observe poor (Engel Class 4) postsurgical outcomes and identify more PGO-activity in SS or NS than in SOZ. Additional studies are needed to further clarify the role of PGOs in epileptic brain. 相似文献
110.
Existing models of causal induction primarily rely on the contingency between the presence and the absence of a causal candidate and an effect. Yet, classification of observations into these four types of covariation data may not be straightforward because (a) most causal candidates, in real life, are continuous with ambiguous, intermediate values and because (b) effects may unfold after some temporal lag, providing ambiguous contingency information. Although past studies suggested various reasons why ambiguous information may not be used during causal induction, the authors examined whether learners spontaneously use ambiguous information through a process called causal assimilation. In particular, the authors examined whether learners willingly place ambiguous observations into one of the categories relevant to the causal hypothesis, in accordance with their current causal beliefs. In Experiment 1, people's frequency estimates of contingency data reflected that information ambiguous along a continuous quantity dimension was spontaneously categorized and assimilated in a causal induction task. This assimilation process was moderated by the strength of the upheld causal hypothesis (Experiment 2), could alter the overall perception of a causal relationship (Experiment 3), and could occur over temporal sequences (Experiment 4). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献