首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1415篇
  免费   269篇
  国内免费   48篇
电工技术   216篇
综合类   71篇
化学工业   172篇
金属工艺   54篇
机械仪表   75篇
建筑科学   200篇
矿业工程   22篇
能源动力   59篇
轻工业   171篇
水利工程   30篇
石油天然气   21篇
武器工业   5篇
无线电   210篇
一般工业技术   141篇
冶金工业   10篇
原子能技术   2篇
自动化技术   273篇
  2024年   6篇
  2023年   91篇
  2022年   135篇
  2021年   187篇
  2020年   171篇
  2019年   79篇
  2018年   54篇
  2017年   48篇
  2016年   48篇
  2015年   48篇
  2014年   150篇
  2013年   124篇
  2012年   177篇
  2011年   97篇
  2010年   70篇
  2009年   56篇
  2008年   32篇
  2007年   46篇
  2006年   56篇
  2005年   13篇
  2004年   16篇
  2003年   2篇
  2002年   10篇
  2001年   2篇
  2000年   3篇
  1999年   4篇
  1998年   2篇
  1996年   3篇
  1994年   1篇
  1992年   1篇
排序方式: 共有1732条查询结果,搜索用时 15 毫秒
1.
随着网络建设以及信息化教学方法在高校教学过程中的应用普及,越来越多的高校使用在线巡课系统对教师的教学过程进行跟踪和管理,以便发现课堂教学中的亮点、问题和不足。文章提出的在线巡课系统,基于声源定位的技术,对传统的在线巡课系统做出了改进,解决了已有巡课系统中“只闻其声,不见其人”的问题,能够更直观地跟踪到教师的教学过程,包括教学行为以及师生互动过程,有效提升教务人员巡课效果和体验感受。  相似文献   
2.
3.
采用鲣鱼为原料,以蛋白质回收率为指标,酶解制备不同工艺条件的样品。通过测定其黄嘌呤氧化酶(XOD)抑制活性、ORAC值、分子质量分布图谱和总氨基酸含量,构建鲣鱼蛋白肽体外化学活性与其分子质量分布图谱、总氨基酸含量图谱之间的谱效关系。结合超高效液相-质谱联用(LC-MS/MS)方法研究其降尿酸肽和抗氧化肽的分布。研究表明,鲣鱼蛋白肽的XOD抑制活性与其ORAC值具有显著的相关性。由多肽分子质量<1ku所占含量的分布区段和脂肪族氨基酸的含量可初步预测鲣鱼蛋白肽的化学活性。质谱分析表明,纯化组分的质谱基峰图在不同时间段的信号强度与鲣鱼蛋白肽的降尿酸活性和抗氧化活性具有明显的相关性。  相似文献   
4.
Negative bias temperature instabilities (NBTI) received little attention pre-2000, but have been intensively investigated post-2000, as they become limiting device lifetime. The relatively thick oxides and low electrical field used in the pre-2000 works make hole injection into oxides negligible. In contrast, hole injection is substantial for most of the post-2000 research that used thin oxides and high fields. This leads to a number of discrepancies between pre- and post-2000 works, in terms of kinetics, recovery, and relative contribution of different types of defects. To account for these discrepancies, a number of models have been proposed. Although these models can fit accelerated test data well, evidences are not enough to convince that they can predict the long term NBTI under low use-Vdd. This article first reviews the discrepancies between pre- and post-2000 works and then uses the Reaction-Diffusion framework as an example to show its inability of prediction for general processes. Evidences for the presence of both As-grown Hole Traps (AHTs) and Generated Defects (GDs) during typical NBTI stresses are presented and techniques for their separation are described. This lays the foundation for the As-grown-Generation (AG) model and its prediction capability will be demonstrated, followed by an analysis why AG model can predict, while others cannot. Finally, speculations are made on the mechanism, defects, and damaging species in terms of holes, hydrogenous species, and their interactions. Although atomic structures of defects are not known, some conditions for their candidates are given.  相似文献   
5.
Small group detection and tracking in crowd scenes are basis for high level crowd analysis tasks. However, it suffers from the ambiguities in generating proper groups and in handling dynamic changes of group configurations. In this paper, we propose a novel delay decision-making based method for addressing the above problems, motivated by the idea that these ambiguities can be solved using rich temporal context. Specifically, given individual detections, small group hypotheses are generated. Then candidate group hypotheses across consecutive frames and their potential associations are built in a tree. By seeking for the best non-conflicting subset from the hypothesis tree, small groups are determined and simultaneously their trajectories are got. So this framework is called joint detection and tracking. This joint framework reduces the ambiguities in small group decision and tracking by looking ahead for several frames. However, it results in the unmanageable solution space because the number of track hypotheses grows exponentially over time. To solve this problem, effective pruning strategies are developed, which can keep the solution space manageable and also improve the credibility of small groups. Experiments on public datasets demonstrate the effectiveness of our method. The method achieves the state-of-the-art performance even in noisy crowd scenes.  相似文献   
6.
This paper investigates the stochastic stability of fuzzy Markovian jumping neural networks with mixed delays in mean square. The mixed delays include time-varying delay and continuously distributed delay. By using the Lyapunov functional method, Jensen integral inequality, the generalized Jensen integral inequality, linear convex combination technique and the free-weight matrix method, several novel sufficient conditions are derived to ensure the global asymptotic stability of the equilibrium point of the considered networks in mean square. The proposed results, which do not require the differentiability of the activation functions, can be easily checked via Matlab software. Finally, two numerical examples are given to demonstrate the effectiveness and less conservativeness of our theoretical results over existing literature.  相似文献   
7.
International Journal of Control, Automation and Systems - The vibration control problem of offshore jacket platforms is studied. The model of offshore platforms with nonlinear interactions of the...  相似文献   
8.
Metabolic reprogramming and immunologic suppression are two critical characteristics promoting the progression of head and neck squamous cell carcinoma (HNSCC). The integrative analysis of all the metabolism-related genes (MRGs) in HNSCC is lacking and the interaction between the metabolism and the immune characteristics also requires more exploration to uncover the potential mechanisms. Therefore, this study was designed to establish a prognostic signature based on all the MRGs in HNSCC. Genes of HNSCC samples were available from the TCGA and GEO databases while the MRGs were retrieved from a previous study. Ultimately 4 prognostic MRGs were selected to construct a model possessing robust prognostic value and accuracy in TCGA cohorts. The favorable reproducibility of this model was confirmed in validation cohorts from GEO databases. The risk score calculated by this model was an independent prognostic factor that further classified these HNSCC patients into high-/low-risk groups. GSEA analyses and somatic mutations indicated the low-risk group could activate several anti-tumor pathways and possessed lower TP53 mutation. The results of ESTIMATE, single-sample GSEA, CIBERSORT, and some immune-related molecules analyses suggested the low-risk group exhibited lower metabolic activities and higher immune characteristics. The Spearman correlation test implied most metabolic pathways with tumor-promoting function were negatively correlated with the immune activity, indicating a plausible approach of combining the anti-metabolism and the immunotherapy drugs in the high-risk group to enhance therapeutic effects than applied separately. In conclusion, this prognostic signature linking MRGs with the immune landscape could promote the individualized treatment for HNSCC patients.  相似文献   
9.
Cell migration is a finely tuned biological process that often involves epithelial-mesenchymal transition (EMT). EMT is typically characterized by the upregulation of mesenchymal markers such as Snail1. This process has been shown to be of critical importance to normal developmental processes, including neural crest migration and invasion. Interestingly, similar mechanisms are utilized in disease processes, such as tumor metastasis and migration. Notably, EMT and EMT-like processes confer tumor cells with the ability to migrate, invade, and adopt stem cell-like properties that largely account for immunosuppression and tumor recurrence. Therefore, identifying sensitive EMT markers may contribute to cancer prognosis and diagnosis in many facets. Previously, we showed that Elp3 plays an essential role during neural crest migration by stabilizing Snail1. In the current study, we further elucidate the molecular mechanism underlying colorectal cancer migration. We found that mElp3 exerted an identical function to xElp3 in modulating neural crest migration, and both HAT and SAM domains are imperative during this migratory process. Interestingly, overexpression of mElp3 in SW480 cells promoted cell migration and invasion, and we further showed that Elp3 stabilized Snail1 requiring integrity of both SAM and HAT domains. Our findings warrant further exploration of the specific target of Elp3 in cancer cells.  相似文献   
10.
Selective laser melting (SLM) is an emerging layer-wise additive manufacturing technique that can generate complex components with high performance. Particulate-reinforced aluminum matrix composites (PAMCs) are important materials for various applications due to the combined properties of Al matrix and reinforcements. Considering the advantages of SLM technology and PAMCs, the novel SLM PAMCs have been developed and researched in recent years. Therefore, the current research progress about the SLM PAMCs is reviewed. Firstly, special attention is paid to the solidification behavior of SLM PAMCs. Secondly, the important issues about the design and fabrication of high-performance SLM PAMCs, including the selection of reinforcement, the influence of parameters on the processing and microstructure, the defect evolution and phase control, are highlighted and discussed comprehensively. Thirdly, the performance and strengthening mechanism of SLM PAMCs are systematically figured out. Finally, future directions are pointed out on the advancement of high-performance SLM PAMCs.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号