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排序方式: 共有447条查询结果,搜索用时 15 毫秒
31.
Martin MD Benton T Bernardo M Woods JS Townes BD Luis H Leitão J Rosenbaum G Castro-Caldas A Pavão I Rue T DeRouen TA 《The Science of the total environment》2007,377(2-3):159-164
Associations between childhood lead exposures and dental caries in children have been reported for over 30 years, with widely varying findings and conclusions, and using measures of lead exposure which ranged from food sources and water to tooth, hair or blood lead concentrations. OBJECTIVES: This study examined the relationship of lead exposure and dental caries in a population of normatively healthy children. METHODS: This cross-sectional study used a population of 507 children aged 8-12 who were participating in a clinical trial of dental materials to examine the relationship between lead and caries. Blood lead concentrations and dental caries were examined for association in both primary and permanent teeth. Because it is possible that neurobehavioral status could be associated with both lead exposure and dental caries prevalence, we also examined neurobehavioral status of the subjects. RESULTS: A gender-specific association (males only) between lead exposure and dental caries was found in primary teeth only. Neurobehavioral measures and IQ were not associated with caries status in this population. CONCLUSIONS: This study did not support neurobehavioral status as mediating any association between lead exposure and caries in a normatively healthy population. A gender-specific association between lead and caries not previously reported was found in primary teeth, and no biological explanation for this has been suggested. We conclude that this study provides only weak evidence, if any, for an association of low-level lead exposure with dental caries. 相似文献
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Kling Kristen C.; Hyde Janet Shibley; Showers Carolin J.; Buswell Brenda N. 《Canadian Metallurgical Quarterly》1999,125(4):470
Two analyses were conducted to examine gender differences in global self-esteem. In Analysis I, a computerized literature search yielded 216 effect sizes, representing the testing of 97,121 respondents. The overall effect size was 0.21, a small difference favoring males. A significant quadratic effect of age indicated that the largest effect emerged in late adolescence (d?=?0.33). In Analysis II, gender differences were examined using 3 large, nationally representative data sets from the National Center for Education Statistics (NCES). All of the NCES effect sizes, which collectively summarize the responses of approximately 48,000 young Americans, indicated higher male self-esteem (ds ranged from 0.04 to 0.24). Taken together, the 2 analyses provide evidence that males score higher on standard measures of global self-esteem than females, but the difference is small. Potential reasons for the small yet consistent effect size are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Experiments are described in which cotton fabrics at different stages of chemical processing were abraded to different extents on a Wira Abrasion Tester with three different abradants, namely, a smooth paper, a similar paper with a rough unfinished surface, and a standard worsted fabric. The three different plain-weave cotton fabrics selected were (a) desized and scoured, (b) bleached and mercerized, and (c) dyed and resin-treated. Scanning electron microscopy revealed that progressive chemical finishing, especially resin-finishing, reduced the abrasion-resistance of these fabrics. The rate of attrition of the cellulosic material at the surface of the fabric was much faster for rough paper than for a smoother type of paper abradant. The crossbred-worsted abradant was less severe than paper in its abrasive action. It also produced, in general, a more fuzzy fabric surface, with several loose fibre ends on the surface. Resin-treated fabrics had fewer of these loose surface fibres than the other two samples, particularly the scoured fabric, which had the most. In the resin-treated fabric, the abraded single fibre ends did not exhibit any twisting, whereas this characteristic feature was rather extensive in the non-resin-finished samples. The lack of twisting and rolling of the fibres probably arose from the constraints imposed by the resin crosslinks, which made the fibres more rigid and caused them to tend to fracture or rupture sharply rather than fibrillate over a somewhat extended length. 相似文献
36.
When taking multiple-choice tests of reading comprehension such as the Scholastic Assessment Test (SAT), test takers use a range of strategies that vary in the extent to which they emphasize reading the questions versus reading the passages. Researchers have challenged the construct validity of these tests because test takers can achieve better-than-chance performance even if they do not read the passages at all. By using an individual-differences approach that compares the relative power of working memory span to predict SAT performance for different test-taking strategies, the authors show that the SAT appears to be tapping reading comprehension processes as long as test takers engage in at least some reading of the passages themselves. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
Major Brenda; Cozzarelli Catherine; Sciacchitano Anne Marie; Cooper M. Lynne; Testa Maria; Mueller Pallas M. 《Canadian Metallurgical Quarterly》1990,59(3):452
Prior to their having a 1st trimester abortion, women's perceptions of social support from their partner, family, and friends and self-efficacy for coping were assessed. Depression, mood, physical complaints, and anticipation of negative consequences were measured after the 30-min recovery period. As predicted, perceived social support enhanced adjustment indirectly through its effects on self-efficacy. Women who perceived high support from their family, friends, and partners had higher self-efficacy for coping. Higher self-efficacy, in turn, predicted better adjustment on the psychological measures but not on the physical complaint measure. No direct path between social support and adjustment was observed. In addition, women who told close others of their abortion but perceived them as less than completely supportive had poorer postabortion psychological adjustment than either women who did not tell or women who told and perceived complete support. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
38.
David R. McLean Brenda J. Page Alan Tuchman Andrew V. Kispert Wen L. Yen
William J. Potter
《Expert systems with applications》1992,5(3-4):441-446Classical planning systems attempt to solve a planning problem by avoiding possible conflicts before the actions are put on a timeline. This is computationally very expensive and the search for all possible future conflicts may be prohibitive. A conflict resolution approach can check for immediate conflicts and try conflict resolution strategies as each activity is put on a timeline without regard for possible future conflicts. A more practical approach is to use a combination of conflict avoidance and conflict resolution based upon heuristics which limit the amount of search required when either is used. Because humans are not good at solving problems which require complex lookahead, this combined approach, with emphasis on conflict resolution, is what human schedulers actually use when they develop schedules. A system which simulates this human approach to scheduling has been developed at NASA's Goddard Space Flight Center for scheduling satellite activities. This system, which includes the Planning And Resource Reasoning (PARR) shell, allows expert schedulers to specify conflict resolution strategies as well as conflict avoidance strategies to be used during the scheduling process. PARR has been used since May 1987 to schedule the Tracking and Data Relay Satellite System services for the Earth Radiation Budget Satellite. PARR will also be used to schedule platform resources on the Explorer Platform, scheduled for launch in early 1992. This paper describes the advantages of using a combined conflict avoidance and resolution approach in a satellite scheduling system. 相似文献
39.
Adler Nancy E.; David Henry P.; Major Brenda N.; Roth Susan H.; Russo Nancy Felipe; Wyatt Gail E. 《Canadian Metallurgical Quarterly》1992,47(10):1194
Psychological research is increasingly involved in debates regarding abortion. While recognizing the diversity of ethical and moral issues intertwined with abortion, the American Psychological Association (APA) has focused its involvement on psychological factors, most recently by appointing an expert panel to review the literature on psychological effects. This article notes the history of APA involvement and reports on the panel's conclusions. It presents evidence that abortion is not likely to be followed by severe psychological responses and that psychological aspects can best be understood within a framework of normal stress and coping rather than a model of psychopathology. Correlates of more negative responses following abortion are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
40.