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641.
Hypogonadic subjects with insulin resistance (IR) showed different metabonomic profiles compared to normo-insulinemic subjects (IS). Testosterone replacement therapy (TRT) may have a different impact on the metabolisms of those with the presence or absence of insulin resistance. We evaluated the changes in the metabolism of IR hypogonadic patients before and after 60 days of TRT. The metabonomic plasma profiles from 20 IR hypogonadal patients were recorded using ultra-high-performance liquid chromatography (UHPLC) and high-resolution mass spectrometry (HRMS). Plasma metabolites, before and after 60 days of TRT, were compared. In hypogonadic patients, carnosine, which is important for improving performance during exercise, increased. Conversely, proline and lysine—amino acids involved in the synthesis of collagen—reduced. Triglycerides decreased and fatty acids (FFAs) increased in the blood as a consequence of reduced FFA β-oxidation. Glycolysis slightly improved, while the Krebs cycle was not activated. Gluconeogenesis (which is the main energy source for hypogonadal IR before TRT) stopped after treatment. As a consequence, lactate and acetyl CoA increased significantly. Both lactate and acetyl CoA were metabolized into ketone bodies which increased greatly, also due to leucine/isoleucine degradation. Ketone bodies were derived predominantly from acetyl CoA because the reaction of acetyl CoA into ketone bodies is catalyzed by mtHMGCoA synthase. This enzyme is inhibited by insulin, which is absent in IR patients but overexpressed following testosterone administration. Ketosis is an alternative route for energy supply and provides the same metabolic effects as insulin but at the metabolic or primitive control level, which bypasses the complex signaling pathway of insulin. After treatment, the hypogonadic patients showed clinical symptoms related to ketonuria. They presented similarly to those following a ketogenic diet, the so-called ‘keto flu’. This must be taken into account before the administration of TRT to hypogonadic patients.  相似文献   
642.
仿生非光滑用于旋成体减阻的试验研究   总被引:4,自引:4,他引:4  
基于仿生非光滑表面具有减粘降阻特性的基本思想,通过仿生非光滑表面控制旋成体附壁区的边界层结构来减小旋成体的阻力。利用6因素3水平的正交试验,考察了对旋成体阻力影响较大的6个因素。对具有不同尺寸的凸包、凹坑以及棱纹等形态的非光滑旋成体及光滑旋成体进行了低、亚、超音速风洞试验,并将减阻率作为试验指标。对减阻率的分析表明,三种非光滑表面均能起到减小旋成体阻力的作用,总阻力最大减阻效果为5%左右。用极差法进行正交试验设计分析,得到了影响旋成体阻力因素的主次顺序及最优水平,并探讨了不同仿生表面对旋成体粘性前部阻力(包括表面摩擦阻力及激波阻力等)及底部阻力的不同影响。  相似文献   
643.
本文研究了通信时延和联合连通切换拓扑条件下的多刚体系统分布式姿态一致性控制问题. 通过构建有 效的辅助向量并选择合适的Lyapunov-Krasovskii函数, 分别对恒定通信时延和时变通信时延两种不同情况下的控 制器进行了设计. 数值仿真结果表明, 本文提出的方法能够有效地解决这类分布式姿态一致性控制问题. 多刚体; 姿态一致性; 联合连通拓扑; 时变时延; Lyapunov函数  相似文献   
644.
为实现入水过程的精细数值仿真,解决入水问题数值模拟所面临的关键技术问题,围绕结构入水过程中固体移动边界的合理描述、自由液面的准确捕捉及流固耦合作用的精细刻画等核心难题,融合计算流体动力学-离散单元法(CFD-DEM)、浸入边界法(IBM)及改进的守恒式Level Set(ICLS)方法,提出了一种CFD-DEM-IBM方法。采用固定的笛卡尔网格离散计算域,分别通过CFD与DEM描述流体与结构运动,引入IBM追踪固体移动边界并获取准确的流固耦合作用力,采用ICLS方法在保证守恒性的同时隐式捕捉自由液面,并通过分区算法,在一个时间步内进行数次交错迭代以反映流固两相间的强耦合效应,建立了高解析度的CFD-DEM-IBM数值模型。通过圆柱常速入水、楔形体对称及非对称入水和多体入水现象仿真分析研究,结果表明,CFD-DEM-IBM方法能够考虑多块体间的相互作用,在准确反映流固耦合效应的同时能够获得高解析度的流场,在多体入水问题处理方面优势显著。  相似文献   
645.
《Ceramics International》2023,49(6):8827-8838
An aqueous colloidal processing method was proposed to prepare m-Li2ZrO3 bodies, with high green density and a homogenous microstructure, employing a pressureless forming technique. For this purpose, the preparation conditions of m-Li2ZrO3 aqueous suspensions were optimized considering colloidal processing variables, such as milling time (0–40 min), dispersant concentration (1–10 wt% of the solids content) and maximum solid loading (41–74 wt%). Particle size distributions and steady-state flow curves of the slips were analyzed, together with phase composition and microstructure of the ceramic bodies. The results show that after planetary ball milling for 30 min, the aqueous suspension with 63.1 wt% of m-Li2ZrO3, and a dispersant content equal to 10 wt% of the solid loading, yielded green bodies with bulk densities close to 66% TD by slip casting. Then, after the heat treatment process at 1100 °C for 12 h, bulk densities close to 88% TD were achieved. It was found that density values and microstructure of the green and sintered products bear a direct relationship to the particle size and the consistency of the slips.  相似文献   
646.
Inverse eigenstrain (inherent strain) analysis methods are shown to be effective for the reconstruction of residual stresses in plane eigenstrain problems (continuously processed bodies) while conversely residual stress reconstruction in discontinuously processed bodies is extremely challenging and necessitates the use of complex regularizing assumptions. Herein, a new generic inverse eigenstrain method suitable for the reconstruction of residual stresses along with residual elastic strains and displacements in discontinuously processed bodies is introduced. The proposed method uses the superposition of eigenstrain radial basis functions together with a set of limited experimental data for model-free (unconstrained) determination of unknown eigenstrain fields. This approach eliminates the limitations introduced by global basis functions such as polynomials. The novel point of this method is the ability to account for all six components of strain in an isotropic body without using regularizing assumptions. By lifting complex guiding formulation, the fidelity of full-field eigenstrain reconstruction becomes directly related to the quality of experimental data and proper discretisation of the model domain. The FEniCS implementation has been validated using the experimental data of pointwise high-energy synchrotron X-ray diffraction measurements from a bent titanium alloy bar. A hybrid high throughput computing approach is also introduced for effective parallel computing.  相似文献   
647.
This article presents a novel load frequency control (LFC) approach using colliding bodies optimizer (CBO) for frequency stabilization of interlinked multiarea electric power systems. The optimal parameters of the suggested CBO-based proportional–integral–derivative-filter controller ascertain an effective LFC solution. First, a well-known and widely used linearized two-area nonreheated thermal power system is examined to demonstrate the efficacy of the proposed approach. The effectiveness of the proposed method is analyzed by comparing the outcomes of several recently presented LFC schemes. The performance analysis shows a settling time improvement of 3.10%, 14.29%, and 18.66% in the case of area-1 and area-2 frequencies and tie-line power deviations compared with an imperialist competitive algorithm (ICA)-based controller. The robustness of the proposed scheme is also evaluated in the presence of various operating scenarios. Additionally, the work is extended to a two-area nonreheated hydrothermal power system. The proposed method shows an improvement of over 60% in the performance index compared with several existing techniques-based controllers such as optics-inspired optimization, gray-wolf optimization, quasi-oppositional differential search algorithm, bacterial foraging optimization algorithm, and ICA.  相似文献   
648.
The modulation of inflammatory responses plays an important role in the pathobiology of cardiac failure. In a natural healing process, the ingestion of apoptotic cells and their apoptotic bodies by macrophages in a focal lesion result in resolution of inflammation and regeneration. However, therapeutic strategies to enhance this natural healing process using apoptotic cell-derived biomaterials have not yet been established. In this study, apoptotic bodies-mimetic nanovesicles derived from apoptotic fibroblasts (ApoNVs) conjugated with dextran and ischemic cardiac homing peptide (CHP) (ApoNV-DCs) for ischemia-reperfusion (IR)-injured heart treatment are developed. Intravenously injected ApoNV-DCs actively targeted the ischemic myocardium via conjugation with CHP, and are selectively phagocytosed by macrophages in an infarcted myocardium via conjugation with dextran. ApoNV-DCs polarized macrophages from the M1 to M2 phenotype, resulting in the attenuation of inflammation. Four weeks after injection, ApoNV-DCs attenuated cardiac remodeling, preserved blood vessels, and prevented cardiac function exacerbation in IR-injured hearts. Taken together, the findings may open a new avenue for immunomodulation using targeted delivery of anti-inflammatory nanovesicles that can be universally applied for various inflammatory diseases.  相似文献   
649.
The bluff body is commonly used to improve micro combustion. The micro combustor with multiple rectangular bluff bodies in a single row was proposed. The effects of bluff bodies on H2/air combustion characteristics were numerically studied. The temperature distributions, ignition position, combustion efficiency and blow-out limit were investigated via changing the total width and number of bluff bodies. The results show that the combined use of multiple bluff bodies can further expand the blow-out limit of H2/Air. The effect of high temperature and viscous force on the flow velocity is main factors for the flame morphology. When the total width of bluff bodies is 2 mm, the blow-out limit decreases with the increase of bluff body number. When the total width of bluff bodies is 4 mm and 6 mm, the blow-out limit increases with the increase of the number of bluff bodies. With the increase of inlet velocity, the complete combustion efficiency decreases. The combustion efficiency in the combustor with wider blow-out limit decreases more slowly. It indicates that the combustor with multi-bluff bodies is more suitable for the operation conditions with high flow velocity.  相似文献   
650.
针对电站锅炉用大型阀体等枝杈管类零件的金属塑性成型 ,提出了“剪切挤压”新工艺 .并对阀体剪挤成型过程进行数值分析和模拟实验研究 ,得到了成型过程中金属流动规律 ,进而为获得阀体剪挤的最佳成型工艺参数提供依据 .最终在 10 0 0 0kN螺旋压力机上成功地锻造出大型高压截止阀阀体 .  相似文献   
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