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   1239篇
  免费   83篇
  国内免费   1篇
电工技术   12篇
化学工业   652篇
金属工艺   23篇
机械仪表   15篇
建筑科学   17篇
能源动力   25篇
轻工业   164篇
水利工程   3篇
石油天然气   9篇
无线电   36篇
一般工业技术   216篇
冶金工业   25篇
原子能技术   5篇
自动化技术   121篇
  2024年   5篇
  2023年   38篇
  2022年   196篇
  2021年   183篇
  2020年   51篇
  2019年   36篇
  2018年   46篇
  2017年   50篇
  2016年   60篇
  2015年   48篇
  2014年   82篇
  2013年   61篇
  2012年   73篇
  2011年   73篇
  2010年   39篇
  2009年   43篇
  2008年   57篇
  2007年   37篇
  2006年   33篇
  2005年   29篇
  2004年   20篇
  2003年   12篇
  2002年   13篇
  2001年   7篇
  2000年   7篇
  1999年   1篇
  1998年   7篇
  1997年   8篇
  1996年   2篇
  1995年   1篇
  1993年   1篇
  1982年   1篇
  1980年   1篇
  1964年   1篇
  1959年   1篇
排序方式: 共有1323条查询结果,搜索用时 15 毫秒
991.
992.
We introduce a logic of evidence-based knowledge in which the evidence part is based on logicof proofs with negative checker . The later is obtained from the Logic of proofs by adding a new unary operation of negativechecker ‘?’ and the corresponding axiom. We defineKripke-style models for and prove the completeness with respect to this semantics. Wealso define the logic of justified knowledge for .  相似文献   
993.
Models of bursting in single cells typically include two subsystems with different timescales. Variations in one or more slow variables switch the system between a silent and a spiking state. We have developed a model for bursting in the pituitary lactotroph that does not include any slow variable. The model incorporates fast, noninactivating calcium and potassium currents (the spike-generating mechanism), as well as the fast, inactivating A-type potassium current (I(A)). I(A) is active only briefly at the beginning of a burst, but this brief impulse of I(A) acts as a burst trigger, injecting the spike trajectory close to an unstable steady state. The spiraling of the trajectory away from the steady state produces a period of low-amplitude spiking typical of lactotrophs. Increasing the conductance of A-type potassium current brings the trajectory closer to the unstable steady state, increasing burst duration. However, this also increases interburst interval, and for larger conductance values, all activity stops. To our knowledge, this is the first example of a physiologically based, single-compartmental model of bursting with no slow subsystem.  相似文献   
994.
: Cardiotocography (CTG) represents the fetus’s health inside the womb during labor. However, assessment of its readings can be a highly subjective process depending on the expertise of the obstetrician. Digital signals from fetal monitors acquire parameters (i.e., fetal heart rate, contractions, acceleration). Objective:: This paper aims to classify the CTG readings containing imbalanced healthy, suspected, and pathological fetus readings. Method:: We perform two sets of experiments. Firstly, we employ five classifiers: Random Forest (RF), Adaptive Boosting (AdaBoost), Categorical Boosting (CatBoost), Extreme Gradient Boosting (XGBoost), and Light Gradient Boosting Machine (LGBM) without over-sampling to classify CTG readings into three categories: healthy, suspected, and pathological. Secondly, we employ an ensemble of the above-described classifiers with the over-sampling method. We use a random over-sampling technique to balance CTG records to train the ensemble models. We use 3602 CTG readings to train the ensemble classifiers and 1201 records to evaluate them. The outcomes of these classifiers are then fed into the soft voting classifier to obtain the most accurate results. Results:: Each classifier evaluates accuracy, Precision, Recall, F1-scores, and Area Under the Receiver Operating Curve (AUROC) values. Results reveal that the XGBoost, LGBM, and CatBoost classifiers yielded 99% accuracy. Conclusion:: Using ensemble classifiers over a balanced CTG dataset improves the detection accuracy compared to the previous studies and our first experiment. A soft voting classifier then eliminates the weakness of one individual classifier to yield superior performance of the overall model.  相似文献   
995.
We study open nets as Petri net models of web services, with a link to the practically relevant language WS-BPEL. For those nets, we investigate the problem of operability which we consider as fundamental as the successful notion of soundness for workflow nets, i.e., Petri net models of business processes and workflows. While we could give algorithmic solutions to the operability problem for subclasses of open nets in earlier work, this article shows that the problem is in general undecidable.  相似文献   
996.
The results of measurements of the aerosol optical thickness (AOT) of the atmosphere by CIMEL Sun–sky radiometers are analysed. In arid zones, days with values of AOT not greater than 0.02 are common. In these cases, the sky radiance in backward hemisphere in the visible wavelength range is practically fully determined by the molecular scattering, which is well studied up to date. This fact opens up possibilities to estimate the errors in measuring sky radiance comparing observed and calculated data, as well as to separate them into random and systematic.  相似文献   
997.
998.
In experimental work as well as in computational applications for which limited computational resources are available for the numerical calculations a coarse mesh problem frequently appears. In particular, we consider here the problem of numerical integration when the integrand is available only at nodes of a coarse uniform computational grid. Our research is motivated by the coarse mesh problem arising in ecological applications such as pest insect monitoring and control. In our study we formulate a criterion for assessing mesh coarseness and demonstrate that the definition of a coarse mesh depends on the integrand function. We then discuss the accuracy of computations on coarse meshes to conclude that the conventional methods used to improve accuracy on fine meshes cannot be applied to coarse meshes. Our discussion is illustrated by numerical examples.  相似文献   
999.
This article considers automatic performance tuning of time-step-based parallel solution methods for initial value problems (IVPs) of systems of ordinary differential equations (ODEs). We apply auto-tuning to the parallel execution of a class of explicit predictor–corrector (PC) methods of Runge–Kutta (RK) type on shared-memory architectures. The performance of parallel multi-threaded implementation variants of these methods depends on various factors only known at runtime, for example, the coupling structure of the ODE system to be solved, the memory access pattern resulting from this coupling structure, and the number of threads executing the program.  相似文献   
1000.
Awareness systems have attracted significant research interest for their potential to support interpersonal relationships. Investigations of awareness systems for the domestic environment have suggested that such systems can help individuals stay in touch with dear friends or family and provide affective benefits to their users. Our research provides empirical evidence to refine and substantiate such suggestions. We report our experience with designing and evaluating the ASTRA awareness system, for connecting households and mobile family members. We introduce the concept of connectedness and its measurement through the Affective Benefits and Costs of communication questionnaire (ABC-Q). We inform results that testify the benefits of sharing experiences at the moment they happen without interrupting potential receivers. Finally, we document the role that lightweight, picture-based communication can play in the range of communication media available.
Natalia Romero (Corresponding author)Email:
Panos MarkopoulosEmail:
Joy van BarenEmail:
Boris de RuyterEmail:
Wijnand IJsselsteijnEmail:
Babak FarshchianEmail:
  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