全文获取类型
收费全文 | 172858篇 |
免费 | 15529篇 |
国内免费 | 11321篇 |
专业分类
电工技术 | 29399篇 |
技术理论 | 7篇 |
综合类 | 16491篇 |
化学工业 | 8943篇 |
金属工艺 | 6547篇 |
机械仪表 | 15977篇 |
建筑科学 | 14936篇 |
矿业工程 | 6890篇 |
能源动力 | 4626篇 |
轻工业 | 4491篇 |
水利工程 | 5427篇 |
石油天然气 | 5585篇 |
武器工业 | 2636篇 |
无线电 | 13582篇 |
一般工业技术 | 7857篇 |
冶金工业 | 7468篇 |
原子能技术 | 1192篇 |
自动化技术 | 47654篇 |
出版年
2024年 | 250篇 |
2023年 | 1835篇 |
2022年 | 3024篇 |
2021年 | 3821篇 |
2020年 | 4616篇 |
2019年 | 3635篇 |
2018年 | 3237篇 |
2017年 | 4829篇 |
2016年 | 5424篇 |
2015年 | 6042篇 |
2014年 | 11623篇 |
2013年 | 9982篇 |
2012年 | 12686篇 |
2011年 | 13662篇 |
2010年 | 10351篇 |
2009年 | 10647篇 |
2008年 | 10687篇 |
2007年 | 13143篇 |
2006年 | 11744篇 |
2005年 | 10313篇 |
2004年 | 8556篇 |
2003年 | 7537篇 |
2002年 | 6006篇 |
2001年 | 4972篇 |
2000年 | 4186篇 |
1999年 | 3326篇 |
1998年 | 2524篇 |
1997年 | 2190篇 |
1996年 | 1760篇 |
1995年 | 1480篇 |
1994年 | 1258篇 |
1993年 | 900篇 |
1992年 | 722篇 |
1991年 | 545篇 |
1990年 | 415篇 |
1989年 | 367篇 |
1988年 | 259篇 |
1987年 | 152篇 |
1986年 | 112篇 |
1985年 | 110篇 |
1984年 | 154篇 |
1983年 | 118篇 |
1982年 | 113篇 |
1981年 | 79篇 |
1980年 | 54篇 |
1979年 | 64篇 |
1978年 | 48篇 |
1977年 | 48篇 |
1964年 | 13篇 |
1959年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
TETSUYA OJIRO HIDEKI HONDA KAZUHIRO TSURUTA TSUYOSHI HANAMOTO 《Electrical Engineering in Japan》2018,203(2):39-46
At present, many industrial carrier devices utilize linear motor sliders. However, a heavier load requires a linear motor (which is an example of a direct drive device) to get higher power, compared with a rotary motor with a ball screw slider (which is an example of an indirect drive device). In order to obtain higher power at a lower cost, a linear slider with multiple motors can be utilized, for example, a gantry type linear motor slider. Moving the gantry type slider requires two linear motors that are set up in parallel to enable synchronization control. Some conventional synchronization control methods have been proposed for the parallel twin linear slider; however, a large‐scaled gantry type linear motor slider has two unique problems: mechanical distortion caused by the limitations of installation environment and coupling caused by joints with low stiffness. This paper proposes a control model to solve these problems, and an identification method of each parameter. Furthermore, the effectiveness of the control model is verified by comparison with simulation results and experimental results. 相似文献
52.
Parallel Multipopulation Differential Evolutionary Particle Swarm Optimization for Voltage and Reactive Power Control 下载免费PDF全文
This paper presents parallel multipopulation differential evolutionary particle swarm optimization (DEEPSO) for voltage and reactive power control (VQC). The problem can be formulated as a mixed integer nonlinear optimization problem and various evolutionary computation techniques have been applied to the problem including PSO, differential evolution (DE), and DEEPSO. Since VQC is one of the online controls, speed‐up of computation is required. Moreover, there is still room for improvement in solution quality. This paper applies parallel multipopulation DEEPSO in order to speed up the calculation and improve solution quality. The proposed method is applied to IEEE 30, 57, and 118 bus systems. The results indicate that the proposed method can realize fast computation and minimize more active power losses than the conventional evolutionary computation techniques. 相似文献
53.
Wenyuan Zhou Chasity P. Hankinson Prof. Dr. Alexander Deiters 《Chembiochem : a European journal of chemical biology》2020,21(13):1832-1836
We have developed a new tool for the optical control of cellular ATP concentrations with a photocaged adenylate kinase (Adk). The photocaged Adk is generated by substituting a catalytically essential lysine with a hydroxycoumarin-protected lysine through site-specific unnatural amino acid mutagenesis in both E. coli and mammalian cells. Caging of the critical lysine residue offers complete suppression of Adk's phosphotransferase activity and rapid restoration of its function both in vitro and in vivo upon optical stimulation. Light-activated Adk renders faster rescue of cell growth than chemically inducible expression of wild-type Adk in E. coli as well as rapid ATP depletion in mammalian cells. Thus, caging Adk provides a new tool for direct conditional perturbation of cellular ATP concentrations thereby enabling the investigation of ATP-coupled physiological events in temporally dynamic contexts. 相似文献
54.
Lokesh Kulhari Kanad Ray Ankit Paptan Nikhil Suri Pramod K Khanna 《International Journal of Applied Ceramic Technology》2020,17(3):1430-1439
Low temperature co-fired ceramic (LTCC) micro-hotplates show wide applications in gas sensors and micro-fluidic devices. It is easily structured in three-dimensional structures. This paper presents the low power consumption micro-hotplates which were developed with PTC (positive temperature coefficient) temperature sensor and inter-digitated electrodes. The paper presents two different structures for micro-hotplate with platinum as a heating element. The PTC temperature sensor using two different materials viz. PdAg and platinum paste are developed with micro-hotplates. The simulation has been achieved through COMSOL for LTCC and alumina micro-hotplates. The temperature variation with power consumption has been measured for the developed LTCC micro-hotplates. The change in resistance of PTC temperature sensors was measured with micro-hotplate temperature. The aim of this study was to place a temperature sensor with the gas sensor module to measure and control the temperature of micro-hotplate. A SnO2 sensing layer is coated on LTCC micro-hotplate using screen printing and characterized for the sensing of carbon monoxide gas (CO). This study will be beneficial for designing hotplates based on LTCC technology with low power consumption and better stability of temperature for gas-sensing applications. 相似文献
55.
Julio Flores-Gonzalez Juan Carlos Cancino-Díaz Leslie Chavez-Galan 《International journal of molecular sciences》2020,21(22)
Recent advances in the field of flow cytometry (FCM) have highlighted the importance of incorporating it as a basic analysis tool in laboratories. FCM not only allows the identification of cell subpopulations by detecting the expression of molecules in the cell membrane or cytoplasm, but it can also quantify and identify soluble molecules. The proper functioning of the FCM requires six fundamental systems, from those related to the transport of events to the systems dedicated to the analysis of information. In this review, we have identified the main considerations that every FCM user must know for an optimal antibody panel design, the quality systems that must govern the FCM protocols to guarantee reproducible results in research or clinical laboratories. Finally, we have introduced the current evidence that highlights the relevance of FCM in the investigation and clinical diagnosis of respiratory diseases, establishing important advances in the basic and clinical study of diseases as old as Tuberculosis along with the recent proposals for the monitoring and classification of patients infected with the new SARS-CoV2 virus. 相似文献
56.
为了降低机床等待过程中的能耗,提出了一种实时数据驱动的机床等待时间预测与节能控制方法。首先,建立了射频识别驱动的生产进度评估方法,并以生产进度数据作为输入,构建了基于堆栈降噪自编码的机床等待时间预测模型;其次,依据预测的机床等待时间,提出了机床状态切换方法,以降低机床能耗;最后,通过一个电梯零部件制造车间的案例分析,表明该方法的预测误差仅为4.1%,同时将机床等待过程能耗降低了57%,实现了制造车间的节能减排。 相似文献
57.
为了避免和减轻由过大隔震层位移引起的损害,对基础隔震框架结构装设调频液柱阻尼器(tuned liquid column damper,简称TLCD)后混合系统的减振效果进行研究。建立了单层和多层混合控制系统在地震作用下的运动方程,采用TLCD-结构体系转化为调频质量阻尼器(tuned mass damper,简称TMD)-结构体系的等效方法,利用TMD参数优化公式,得到单个TLCD初始设计参数,并采用状态空间方程得到多个TLCD最优设计参数。通过对某8层基础隔震结构进行模拟,证明了该理论设计方法的合理性。该混合结构不仅可以减小隔震层位移和加速度,而且对上部结构位移和加速度反应都能更有效的控制。 相似文献
58.
贵州地区煤层赋存条件复杂,煤层间距小,相邻采空区存在漏风通道的问题。采用SF6示踪法及重点区域指标气体数据分析法,对发耳煤矿采空区漏风规律及其治理措施进行研究。分析结果表明,由于相邻密闭效果欠佳,导致31004开切眼联络巷及31004工作面回风巷密闭漏风严重。31004采空区漏风通道主要是31004开切眼联络巷密闭及10^#煤层开采过程中对上部7^#煤层采空区造成二次扰动形成的纵向漏风通道;漏风量为83 m^3/min,采空区风速约为0.17 m/s。对存在的煤自燃隐患采取了注水降温措施,CO体积分数显著下降至(5~9)×10^-6。为即将开采的50105、50107工作面的煤自燃防控提供了科学依据和管控措施方案。 相似文献
59.
This paper proposes an adaptive super-twisting decoupled terminal sliding mode control technique for a class of fourth-order systems. The adaptive-tuning law eliminates the requirement of the knowledge about the upper bounds of external perturbations. Using the proposed control procedure, the state variables of cart-pole system are converged to decoupled terminal sliding surfaces and their equilibrium points in the finite time. Moreover, via the super-twisting algorithm, the chattering phenomenon is avoided without affecting the control performance. The numerical results demonstrate the high stabilization accuracy and lower performance indices values of the suggested method over the other ones. The simulation results on the cart-pole system as well as experimental validations demonstrate that the proposed control technique exhibits a reasonable performance in comparison with the other methods. 相似文献
60.
This paper investigates the event-triggered decentralized adaptive tracking problem of a class of uncertain interconnected nonlinear systems with unexpected actuator failures. It is assumed that local control signals are transmitted to local actuators with time-varying faults whenever predefined conditions for triggering events are satisfied. Compared with the existing control-input-based event-triggering strategy for adaptive control of uncertain nonlinear systems, the aim of this paper is to propose a tracking-error-based event-triggering strategy in the decentralized adaptive fault-tolerant tracking framework. The proposed approach can relax drastic changes in control inputs caused by actuator faults in the existing triggering strategy. The stability of the proposed event-triggering control system is analyzed in the Lyapunov sense. Finally, simulation comparisons of the proposed and existing approaches are provided to show the effectiveness of the proposed theoretical result in the presence of actuator faults. 相似文献