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71.
隧道开挖技术中的放样工序目前主要用手工操作,难度大精度低成本高,需要发展激光隧道断面放样技术。本文提出的激光隧道断面放样方法,包括平移物镜扫描,光束发散我遥压缩,扫描光点的计算机数字控制(CNC),光电零位恢复装置,及仪器精确定信方法。理论分析和样机的试用这一放样方法是成功的。  相似文献   
72.
CNC车床的故障概率模型   总被引:6,自引:0,他引:6  
本文从CNC车床的故障数据的采集入手,建立了CNC车床的故障数据库。应用模糊综合评价的方法对CNC车床的故障模型进行了分析  相似文献   
73.
刘民  吴澄 《电子学报》1999,27(7):132-134
随着CIMS技术的发展,生产线调度问题的研究显得日益重要,最小化拖用期任务数并行机调度问题是一类重要的生产线调度问题,但迄今为止,在解决工件和机器数较多的大规模并行机调度问题还存在着许多困难,进化规划方法与遗传算法一样是一种重要的进化计算方法,它具有描述简单,使用灵活,运行效率高,鲁棒性强,较少受初始条件限制等优点,这使得它有很高的实用价值,但与遗传算法相比,进化规划方法的应用还刚刚开始,特别是在  相似文献   
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利用从头算MP2方法优化了Pt(CN)2(CNCH3)2,Pt(CN)2(CNCH3)2-(NCCH3)2.「Pt(CN)2.(CNCH3)2」2的在态几何结构,利用单激发的组态相互作用方法(CIS)计算了固态和乙氰溶液中标题化合物的发射光谱,并对激发态的几何结构进行了优化,结果表明,基态时,Pt...NCCH3之间的距离较大(0.406nm),说明溶剂分子与Pt原子之间存在较小的范德华作用;而激发时,Pt...NCCH3之间的距离减小(0.257nm),说明此时Pt...NCCH3之间相互作用较强,由于这种作用使乙氰溶液中该物质的发光性质与不考虑溶剂效应时相比差异较大,其发射光谱不可我谱区,固态时,此化合物为直线链状结构,MP2计算得到:基态时「Pt(CN)2(CNCH3)2」2中Pt...Pt之间的距离为0  相似文献   
76.
 A laboratory information management system (LIMS) can make a major contribution to the quality and therefore to the efficiency and competitiveness of a laboratory. Since it can impact all aspects of a laboratory's organization it must be the key if not the principal player of the laboratory's quality system. It should support the laboratory in establishing, maintaining and applying quality procedures thereby enabling the laboratory to achieve its quality goals. As a tool, LIMS permits the laboratory to input and use its own know-how and experience to optimize the total organization (internal and external) and workflow of generated information. However, perceived "quality" in the context of an LIMS, can be viewed as being made up of different facets such as the security, reliability and accessibility of information as well as its turn around time and production cost. This paper reviews the role of a LIMS in the laboratory and the contribution that both system design and functionality can have on "building quality ". Received: 5 October 1998 · Accepted: 20 October 1998  相似文献   
77.
Machine modeling was used to investigate the kinetic mechanism of the gas-phase oxidation of carbon disulfide at elevated temperatures. The scheme of the process examined includes 70 elementary reactions. On the basis of the kinetic data on these reactions available in the literature the rates of the oxidation process, the concentrations of end products and intermediate particles were calculated as a function of the time under various conditions (composition, pressure, temperature). Comparison of the results obtained with the experimental data showed satisfactory agreement and also revealed some important elementary reactions.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow 117977. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 812–822, April, 1992.  相似文献   
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Mutasynthesis of pyrichalasin H from Magnaporthe grisea NI980 yielded a series of unprecedented 4′-substituted cytochalasin analogues in titres as high as the wild-type system (≈60 mg L−1). Halogenated, O-alkyl, O-allyl and O-propargyl examples were formed, as well as a 4′-azido analogue. 4′-O-Propargyl and 4′-azido analogues reacted smoothly in Huisgen cycloaddition reactions, whereas p-Br and p-I compounds reacted in Pd-catalysed cross-coupling reactions. A series of examples of biotin-linked, dye-linked and dimeric cytochalasins was rapidly created. In vitro and in vivo bioassays of these compounds showed that the 4′-halogenated and azido derivatives retained their cytotoxicity and antifungal activities; but a unique 4′-amino analogue was inactive. Attachment of larger substituents attenuated the bioactivities. In vivo actin-binding studies with adherent mammalian cells showed that actin remains the likely intracellular target. Dye-linked compounds revealed visualisation of intracellular actin structures even in the absence of phalloidin, thus constituting a potential new class of actin-visualisation tools with filament-barbed end-binding specificity.  相似文献   
80.
System ringing is one of the most important factors affecting the quality of data obtained in high speed dynamic material tests using servo-hydraulic machines. This phenomenon is characterized by vibrations originated by the excitation of predominant modes of the machine during tests, producing distinctive waves in material curves that severely distort the required results. In the specialized literature, the quantitative study of these vibrations has mainly been carried out considering the testing machine as a single degree of freedom system, which has led to a general understanding of the variables involved in the process. However, discrepancies between analytical predictions and experimental observations have been detected using the single degree of freedom approach, so the need for further detailed study of machine dynamic characteristics has been reported. The work presented in this paper addresses this requirement by means of a detailed characterization of the dynamic behavior of a MTS 819.10 high rate testing system. Natural frequencies, mode shapes and damping factors have been obtained from an experimental modal analysis performed on the machine and a mathematical model of the process has been developed from these modal parameters. This model has been used to detect the modes that have the greatest influence in system ringing when testing rubber at high strain rates, and to predict quantitatively the amplitudes of vibrations produced in the process. Material curves have been corrected by subtracting the predicted undulations from the original measurements, obtaining smooth curves that adequately reflect the real material behavior at high strain rates and, thus, demonstrating the effectiveness of the proposed procedure. Although the research conducted in this work has been focused on rubber, the procedure can be extended equally to characterize other materials, thus constituting a valuable tool to correct experimental measurements contaminated by ringing.  相似文献   
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