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21.
针对基于PC机和专用运动控制卡的传统数控系统的不足,提出了ARM微处理器(S3C2440)和数字信号处理芯片DSP(TMSC6713)双CPU主从式结构硬件平台,嵌入式Linux操作系统软件平台构建嵌入式运动控制器的方法;分别介绍了此嵌入式运动控制器主从控制板的硬件结构设计;软件方面,在Linux2.6内核环境下设计了FPGA的驱动程序,并给出了基于MiniGUI的人机界面设计以及DSP软件实现的程序结构框架;测试结果表明,该运动控制器工作可靠、运算能力强、结构灵活,精度达到1μm,在实践中有一定的借鉴意义。 相似文献
22.
Design sensitivity analysis of flexible multibody systems is important in optimizing the performance of mechanical systems.
The choice of coordinates to describe the motion of multibody systems has a great influence on the efficiency and accuracy
of both the dynamic and sensitivity analysis. In the flexible multibody system dynamics, both the floating frame of reference
formulation (FFRF) and absolute nodal coordinate formulation (ANCF) are frequently utilized to describe flexibility, however,
only the former has been used in design sensitivity analysis. In this article, ANCF, which has been recently developed and
focuses on modeling of beams and plates in large deformation problems, is extended into design sensitivity analysis of flexible
multibody systems. The Motion equations of a constrained flexible multibody system are expressed as a set of index-3 differential
algebraic equations (DAEs), in which the element elastic forces are defined using nonlinear strain-displacement relations.
Both the direct differentiation method and adjoint variable method are performed to do sensitivity analysis and the related
dynamic and sensitivity equations are integrated with HHT-I3 algorithm. In this paper, a new method to deduce system sensitivity
equations is proposed. With this approach, the system sensitivity equations are constructed by assembling the element sensitivity
equations with the help of invariant matrices, which results in the advantage that the complex symbolic differentiation of
the dynamic equations is avoided when the flexible multibody system model is changed. Besides that, the dynamic and sensitivity
equations formed with the proposed method can be efficiently integrated using HHT-I3 method, which makes the efficiency of
the direct differentiation method comparable to that of the adjoint variable method when the number of design variables is
not extremely large. All these improvements greatly enhance the application value of the direct differentiation method in
the engineering optimization of the ANCF-based flexible multibody systems. 相似文献
23.
24.
Helena Kratochvílov Milo Mrz Barbora J. Kasperov Daniel Hlav
ek Jakub Mahrík Ivana Lakov Anna Cinkajzlov Zdenk Matloch Zdeka Lacinov Jaroslava Trnovsk Peter Ivk Peter Novodvorský Ivan Netuka Martin Haluzík 《International journal of molecular sciences》2021,22(9)
The aim of our study was to analyze mitochondrial and endoplasmic reticulum (ER) gene expression profiles in subcutaneous (SAT) and epicardial (EAT) adipose tissue, skeletal muscle, and myocardium in patients with and without CAD undergoing elective cardiac surgery. Thirty-eight patients, 27 with (CAD group) and 11 without CAD (noCAD group), undergoing coronary artery bypass grafting and/or valvular surgery were included in the study. EAT, SAT, intercostal skeletal muscle, and right atrium tissue and blood samples were collected at the start and end of surgery; mRNA expression of selected mitochondrial and ER stress genes was assessed using qRT-PCR. The presence of CAD was associated with decreased mRNA expression of most of the investigated mitochondrial respiratory chain genes in EAT, while no such changes were seen in SAT or other tissues. In contrast, the expression of ER stress genes did not differ between the CAD and noCAD groups in almost any tissue. Cardiac surgery further augmented mitochondrial dysfunction in EAT. In our study, CAD was associated with decreased expression of mitochondrial, but not endoplasmic reticulum stress genes in EAT. These changes may contribute to the acceleration of coronary atherosclerosis. 相似文献
25.
Joanna Czajkowska Adam Junka Jakub Hoppe Monika Toporkiewicz Andrzej Pawlak Pawe Migda Monika Oleksy-Wawrzyniak Karol Fijakowski Marcin
miglak Agata Markowska-Szczupak 《International journal of molecular sciences》2021,22(11)
Staphylococcus aureus is one of the most prevalent pathogens associated with several types of biofilm-based infections, including infections of chronic wounds. Mature staphylococcal biofilm is extremely hard to eradicate from a wound and displays a high tendency to induce recurring infections. Therefore, in the present study, we aimed to investigate in vitro the interaction between S. aureus biofilm and fibroblast cells searching for metabolites that could be considered as potential biomarkers of critical colonization and infection. Utilizing advanced microscopy and microbiological methods to examine biofilm formation and the staphylococcal infection process, we were able to distinguish 4 phases of biofilm development. The analysis of staphylococcal biofilm influence on the viability of fibroblasts allowed us to pinpoint the moment of critical colonization—12 h post contamination. Based on the obtained model we performed a metabolomics analysis by 1H NMR spectroscopy to provide new insights into the pathophysiology of infection. We identified a set of metabolites related to the switch to anaerobic metabolism that was characteristic for staphylococcal biofilm co-cultured with fibroblast cells. The data presented in this study may be thus considered a noteworthy but preliminary step in the direction of developing a new, NMR-based tool for rapid diagnosing of infection in a chronic wound. 相似文献
26.
Reactor blends of polyethylene/poly(ethylene-co-1-octene) resins with bimodal molecular weight and bimodal short chain branching distributions were synthesized in a two-step polymerization process. The compositions of these blends range from low molecular weight (LMW) homopolymer to high molecular weight (HMW) copolymer and vice versa HMW homopolymer to LMW copolymer. The shear flow characteristics of these polymers in the typical processing range mostly depend on the molecular weight and MWD of the polymer and are independent of the short chain branch content. From oscillatory shear measurements, it was observed that the viscosity of HMW polymers was reduced with the addition of LMW material. For the polymers produced with this two-step polymerization process, the LMW homopolymer and HMW copolymer blends and HMW homopolymer and LMW copolymer blends were melt miscible, despite the large viscosity differences of the pure components. 相似文献
27.
Reactor blends of polyethylene/poly(ethylene-co-1-octene) resins with bimodal molecular weight and bimodal short chain branching distributions were synthesized in a two-step polymerization process. The compositions of these blends range from low molecular weight (LMW) homopolymer to high molecular weight (HMW) copolymer and, vice versa, HMW homopolymer to LMW copolymer. The physical properties of the blends were found to be consistent with the nature of the individual components. For the tensile properties, the stiffness decreases with increasing the fraction of the copolymer, regardless of the molecular weight of the homopolymer fraction. For these blends with bimodal microstructures, it was confirmed that the degree of crystallinity governs the stiffness of the polymer. However, the energy dampening properties of the polymers benefit from the presence of the copolymer. A balance of stiffness and toughness can be obtained by altering the composition of the blends. For some blends, the presence of HMW homopolymer can dominate the tensile properties, showing little variation in the stiffness with increased addition of copolymer. It was also demonstrated that the testing conditions and thermal treatment of the polymer greatly influence the resulting elastic and energy dampening properties. Depending on the desired application, annealing these polymers (especially very low density copolymers) not only increases the crystallinity and stiffness, but also changes the frequency response of the dynamic mechanical properties. 相似文献
28.
29.
CuS pineal microspheres congregated from interleaving nanoflakes with thickness of 40 to 200 nm were synthesized by a pyridine-solvothermal process via the reaction between cupric chloride(CuCl2·2H2O) and thioacetamide(TAA,CH3CSNH2).The products were characterized by X-ray diffraction and scanning electron microscopy.UV-Vis absorption spectrum,excitation and photoluminescence spectra of CuS pineal microspheres were obtained at room temperature to investigate their optical properties.A possible growth mechanism on the formation of CuS pineal microspheres is proposed.The factors influencing the evolution of morphologies of CuS crystals including the dosage of the reactants,surfactant,and sulphur-source were also analyzed. 相似文献
30.
The attractiveness of different synthetic host odors and a synthetic aggregation pheromone (grandisoic acid [GA]) to overwintered adult plum curculios (PCs), Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), was examined using two types of traps (sticky panels and black pyramids) placed in border areas surrounding an unsprayed section of an apple orchard in Massachusetts. In 2001, we evaluated the response of PCs to three synthetic fruit volatiles (benzaldehyde [BEN], ethyl isovalerate [EIV], and limonene [LIM]) assessed alone and in combination with GA, as well as the response to GA alone and a no-odor (control) treatment. BEN was the only host volatile that synergized the response of PCs to GA for both trap types. For both trap types, GA was as attractive to PCs as a single component as when in combination with either EIV or LIM. In 2002, four release rates of BEN (0, 2.5, 10, and 40 mg/day) and two release rates of GA (1 and 2 mg/day) were evaluated for attractiveness to PCs using panel and pyramid traps. For panel traps, an increase in amount of GA released (from 1 to 2 mg/day) was associated with a 35% increase in captures. However, PC captures by pyramid traps were similar regardless of the amount of GA released. For panel traps, 10 and 40 mg/day of BEN were the most attractive release rates regardless of the amount of GA released. For pyramid traps baited with GA. PC captures were enhanced by the presence of BEN, regardless of release rate. In 2003, GA at 1 mg/day + BEN at 80 mg/day of release did not enhance PC captures by panel traps relative to lower release rates of BEN. Pyramid traps releasing GA at 1 mg/day performed best when baited with BEN at 10 mg/day of release; a release rate of 80 mg/day of BEN decreased the attractiveness of the binary combination of BEN + GA. Combined results suggest that BEN at 10 mg/day + GA at 1 mg/day of release constitutes an attractive lure that may improve the effectiveness of monitoring traps for PCs. 相似文献