全文获取类型
收费全文 | 31579篇 |
免费 | 5566篇 |
国内免费 | 4500篇 |
专业分类
电工技术 | 1950篇 |
技术理论 | 2篇 |
综合类 | 3401篇 |
化学工业 | 1228篇 |
金属工艺 | 500篇 |
机械仪表 | 1309篇 |
建筑科学 | 2524篇 |
矿业工程 | 481篇 |
能源动力 | 446篇 |
轻工业 | 461篇 |
水利工程 | 553篇 |
石油天然气 | 407篇 |
武器工业 | 320篇 |
无线电 | 3105篇 |
一般工业技术 | 1923篇 |
冶金工业 | 2274篇 |
原子能技术 | 73篇 |
自动化技术 | 20688篇 |
出版年
2024年 | 618篇 |
2023年 | 2034篇 |
2022年 | 3262篇 |
2021年 | 3219篇 |
2020年 | 2614篇 |
2019年 | 1758篇 |
2018年 | 1272篇 |
2017年 | 1173篇 |
2016年 | 1237篇 |
2015年 | 1229篇 |
2014年 | 1847篇 |
2013年 | 1593篇 |
2012年 | 1687篇 |
2011年 | 2055篇 |
2010年 | 1700篇 |
2009年 | 1690篇 |
2008年 | 1656篇 |
2007年 | 1704篇 |
2006年 | 1511篇 |
2005年 | 1282篇 |
2004年 | 1054篇 |
2003年 | 896篇 |
2002年 | 819篇 |
2001年 | 613篇 |
2000年 | 520篇 |
1999年 | 432篇 |
1998年 | 330篇 |
1997年 | 292篇 |
1996年 | 261篇 |
1995年 | 201篇 |
1994年 | 169篇 |
1993年 | 144篇 |
1992年 | 120篇 |
1991年 | 70篇 |
1990年 | 62篇 |
1989年 | 51篇 |
1988年 | 40篇 |
1987年 | 35篇 |
1986年 | 44篇 |
1966年 | 14篇 |
1965年 | 26篇 |
1964年 | 26篇 |
1963年 | 23篇 |
1962年 | 12篇 |
1961年 | 17篇 |
1959年 | 16篇 |
1958年 | 16篇 |
1957年 | 22篇 |
1956年 | 13篇 |
1955年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
151.
This paper describes how SWoRD (scaffolded writing and rewriting in the discipline), a web-based reciprocal peer review system, supports writing practice, particularly for large content courses in which writing is considered critical but not feasibly included. To help students gain content knowledge as well as writing and reviewing skills, SWoRD supports the whole cycle of writing, reviews, back-reviews, and rewriting by scaffolding the journal publication process as its authentic practice model. In addition, SWoRD includes algorithms that compute individual reviewer’s review accuracy, which is in turn used to support the various drawbacks of reciprocal peer reviews (e.g., variation in motivation or ability of reviewers). Finally, this paper describes an empirical evaluation showing that the SWoRD approach is effective in improving writing quality in content classes. 相似文献
152.
低压低渗气藏钻探过程中的保护方案 总被引:1,自引:0,他引:1
针对鄂尔多斯塔巴庙区块低压低渗气藏物理特性复杂的情况,推荐一套切实可行的气层保护方案。即实行全面钻井液监控;采用欠平衡钻井技术;储层保护前期研究;采用与地层流体配伍性好的阳离子钻井液体系;降低钻井完井液的滤失量,API滤失量小于5mL、高温高压滤失量小于15mL、固相含量小于8%、含砂量小于0.3%;根据储层裂缝的宽度和走向使用保护剂;对裸眼完钻的气层利用洗井清除井壁附近的污染带,恢复储层原始渗透率;固井作业防止气窜;采用具有抑制地层水敏、速敏保护气层的优质射孔液;水力压裂优化压裂设计,严格压裂施工。总之,气层保护技术是一个系统工程,任何一个环节的问题,都将对气层产生伤害.因此需加强气层保护研究,做到在钻开气层到投产的每道工序都采取积极有效的气层保护措施。 相似文献
153.
Dr. K. Whybrew J. K. Raine G. R. Dunlop H. Overbye 《The International Journal of Advanced Manufacturing Technology》1993,8(2):111-113
An articulated geometry which overcomes the problem of loss of traction in differentially steered skid tractor automatic guided vehicles is described. 相似文献
154.
讨论了施工方案与工程项目施工质量的关系,得出了正确的施工方案是工程项目施工质量管理的指南,是工程项目施工质量的重要保证的结论,以达到通过完善施工方案来提高工程施工质量的效果。 相似文献
155.
郁江梯级水电站群由西津、仙依滩和桂航3座水电厂组成。针对西津电厂出力变化频繁,加上西津下游两电厂装机容量较小,经常出现弃水,用增量动态规划法进行了联合优化调度探索,同时介绍马斯京根分段流量演算法。 相似文献
156.
Before 12 months of age, infants have difficulties coordinating and sequencing their movements to retrieve an object concealed in a box. This study examined (a) whether young infants can discover effective retrieval solutions and consolidate movement coordination earlier if exposed regularly to such a task and (b) whether different environments, indexed by box transparency, would impact the rate of learning and time of discovery of these solutions. Infants (N=12) were presented with an object retrieval task every week from 6 1/2 months of age until they were able to retrieve the toy from the box using coordinated two-handed patterns for 3 weeks. To reach that criterion, infants tested with an opaque box took 2 1/2 months and infants tested with a semitransparent box took 1 1/2 months. Both groups outperformed age-matched controls who received a one-time exposure to the task. Repeated exposure to the task and vision of the toy significantly enhanced this process of solution discovery. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
157.
Improved Estimates for the Accuracy of Small Disjuncts 总被引:2,自引:0,他引:2
Learning systems often describe a target class as a disjunction of conjunctions of conditions. Recent work has noted that small disjuncts, i.e., those supported by few training examples, typically have poor predictive accuracy. One model of this accuracy is provided by the Bayes-Laplace formula based on the number of training examples covered by the disjunct and the number of them belonging to the target class. However, experiments show that small disjuncts associated with target classes of different relative frequencies tend to have different error rates. This note defines the context of a disjunct as the set of training examples that fail to satisfy at most one of its conditions. An empirical adaptation of the Bayes-Laplace formula is presented that also makes use of the relative frequency of the target class in this context. Trials are reported comparing the performance of the original formula and the adaptation in six learning tasks. 相似文献
158.
The purpose of the present study was to gain a deeper understanding of the role of the basal ganglia in learning and memory by examining learning strategies among patients with basal ganglia dysfunction. Using a probabilistic category learning task (the "weather prediction" task) previously shown to be sensitive to basal ganglia function, the authors examined patterns of performance during learning and used mathematical models to capture different learning strategies. Results showed that patients with Parkinson's disease exhibit different patterns of strategy use. Specifically, most controls initially used a simple, but suboptimal, strategy that focused on single-cue-outcome associations; eventually, however, most controls adopted a more complex, optimal learning strategy, integrating single-cue associations to predict outcomes for multiple-cue stimuli. In contrast, the majority of individuals with Parkinson's disease continued to rely on simple single-cue learning strategies throughout the experiment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
159.
No authorship indicated 《Canadian Metallurgical Quarterly》2006,61(8):811
Presents the citation for Anthony D. Wagner, who received the Award for Distinguished Scientific Early Career Contributions to Psychology (cognition and human learning) "for outstanding and innovative research on the neural basis of memory and executive control." A brief profile and a selected bibliography accompany the citation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
160.
对高填方与高架桥和深路堑与隧道两个典型技术方案,进行了费用分析,寻找方案选择的工程临界值,以提高工程设计的经济性和合理性。重点提出了工程可替代方案间填挖高判断值,对工程可行性研究阶段山岭重丘区的公路工程技术方案的选择有一定参考价值。 相似文献