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91.
Patients with advanced human immunodeficiency virus (HIV) infection are susceptible to infections with Mycobacterium avium complex (MAC). Interleukin (IL)-10 may impair immunity to MAC; therefore, the effect of different MAC preparations on IL-10 production was examined in mononuclear cell cultures from HIV-infected patients. IL-10 levels in cultures for 26 patients were higher than those in 20 control cultures. The highest IL-10 levels were found in cultures from patients with the most advanced HIV disease. Monocytes were the major IL-10 producers, while little IL-10 could be attributed to Th2 lymphocytes. Cultures for patients produced reduced levels of tumor necrosis factor-alpha and normal levels of IL-12; the production of these cytokines increased after neutralization of IL-10. Circulating IL-10 was higher in HIV-infected patients than in controls, with the highest levels in the AIDS group. Elevated monocyte/macrophage-derived IL-10 production may contribute to the high susceptibility to MAC infection seen in patients with advanced HIV disease.  相似文献   
92.
The surface tension and the viscosity of a series of industrial alloys have been measured by the oscillating drop technique with an electromagnetic levitation device under reduced gravity conditions in several parabolic flights. It was demonstrated that the 20 seconds of reduced gravity available in a parabola were sufficient for melting, heating into the liquid phase, and cooling to solidification of typically 7 mm diameter metallic specimen. The surface tension and the viscosity were obtained from the frequency and the damping time constant of the oscillation which were evaluated from the temperature signal of a highresolution pyrometer. Alloys processed included steels, Ni-based superalloys, and Ti-alloys which were supplied by industrial partners to the project. Three to four parabolas were sufficient to obtain the surface tension and the viscosity over a large range in temperature.  相似文献   
93.
94.
Terrain mapping by ground-based interferometric radar   总被引:4,自引:0,他引:4  
The authors propose a ground-based interferometric synthetic aperture radar (SAR) technique for terrain mapping. It is based on a coherent continuous-wave step-frequency (CW-SF) radar moved along a linear horizontal rail. It works synthesising microwave holographic images taken from different points of view to obtain elevation maps by phase comparison. The focusing algorithm for imaging synthetic holograms and digital elevation models (DEM) is able to correct topographic distortion and phase wrap through an iterative multi-baseline procedure  相似文献   
95.
A microwave radar technique for dynamic testing of large structures   总被引:1,自引:0,他引:1  
In this paper, the authors propose an innovative survey radar technique based on microwave holographic images for dynamic testing of large structures providing both vibration amplitude pattern and frequency. Theoretical background is provided and experimental results obtained during a dynamic test on a concrete and masonry building are reported.  相似文献   
96.
Analysis of Ground-Based SAR Data With Diverse Temporal Baselines   总被引:1,自引:0,他引:1  
In this paper, the algorithms developed for satellite synthetic aperture radar (SAR) interferometry were adapted to the ground-based SAR (GB-SAR) configuration and used for detecting the displacements of an alpine landslide which have occurred over many years. Indeed GB-SAR interferometry is based on the same principles as satellite SAR techniques but benefits from the GB-SAR's versatility and capability of gathering many images per day. In monitoring applications of landslides moving only few centimeters per year, as the case here reported, the GB-SAR sensor is installed at repeated intervals several months apart over the observation period. Although the revisiting time is very similar to the satellite one, for each survey, lasting two or three days, more than ten images are available. They are analyzed separately and in combination with images from other surveys for coherent pixel selection. Interferograms are formed by cross-combining images from different surveys. Finally, the evolution of the deformation across the surveys is retrieved in a least square sense without any assumptions on its regularity. The used GB-SAR technique is described in detail in this paper, and the results obtained with regard to a landslide in the Italian Alps that has been monitored over a period of about three years are discussed.  相似文献   
97.
Eucalyptus nitens and E. globulus are wood species used in kraft pulping in Chile and Australia. Although E. nitens adapts very well to cold regions it requires more severe cooking conditions to produce bleachable kraft pulps. An attempt was made to find out whether a pre‐treatment with Ceriporiopsis subvermispora would improve its performance during kraft pulping and the pulp properties. The biotreatment of the chips carried out for a period of 15 days resulted in 13.3% lignin loss and a limited glucan degradation (2%). The pulping of biotreated samples required lower active alkali charge to reach the target kappa number compared to the control untreated sample and exhibited better pulping selectivity. The pulp yield increased by 3% and 1.5% for the pulps of 22 and 16 kappa numbers, respectively. The biotreated pulp's strength properties were improved and were similar to those of E. globulus reference pulp. Copyright © 2006 Society of Chemical Industry  相似文献   
98.
The 18-karat Au43.3Cu31.8Al24.9 alloy displays shape memory effect. The parent phase has L21 structure which transforms to B2 at high temperature. The B2 phase is retained in metastable state by quenching from the B2 field. It then transforms irreversibly with an endothermic peak in Differential Scanning Calorimetry (DSC) to the stable L21 structure in the temperature range between 407 K and 435 K as a function of heating rate. The transformation is, therefore, entropy-driven. Details are reported on the enthalpy of transformation and its temperature dependence. The transformation is discussed with reference to the entropy content of phases as a function of temperature which counteracts austenite stability. The role of vacancy motion is outlined. A comparison is made with analogous transitions occurring in molecular substances and metallic materials.  相似文献   
99.
This in vitro study evaluated the apical sealing ability, bioactivity and biocompatibility of an experimental calcium silicate-based and two light-curing calcium silicate/calcium-phosphate cements as potential root end filling materials. A calcium silicate Portland-based (Control PC), an experimental calcium silicate (Exp. PC) and two light-curing cements (LC-CaP; LC-Si/CaP) were assessed for their alkalinising activity (pH) and biocompatibility. Single-rooted human canines were endodontically treated, filled with gutta-percha and finally submitted to apicoectomy. Root end fillings were performed using all tested cements, and their apical sealing ability was evaluated up to 4 weeks of immersion in simulated body fluid (SBF). The mineral precipitation at the apical region and the cement adaptation to root dentine were also evaluated through non-destructive optical microscopy both at 24?h and after prolonged water storage (four week). LC-CaP and LC-Si/CaP had neutral pH, the greatest sealing ability (24?h) and excellent cytocompatibility. The Exp. PC cement presented sealing ability after two and four weeks, as well as biocompatibility after four and seven days, similar to LC-CaP and LC-Si/CaP. The control PC cement showed the lowest sealing ability and the greatest cytotoxicity. Mineral precipitation was observed in all groups, while some differences were seen in terms of cement adaptation along the root canal dentine walls. The experimental light-curable cements as well as the experimental PC might be suitable root end filling materials with appropriate (in vitro) sealing ability, biocompatibility and aptitude to induce mineral precipitation.  相似文献   
100.
四川盆地西北部地区处于龙门山断褶带北段,地表地势变化剧烈、地腹断层发育、地震资料品质差、构造落实难;主要目的层——中二叠统栖霞组埋藏深、储层薄、非均质性强、地震预测难度大。为此,通过开展地震采集、处理、解释联合攻关,形成了适合地面、地下双复杂构造的地震勘探配套技术:(1)通过表层结构调查、动态井深岩性识别、单点检波器埋置工具及工艺优化激发接收参数,采用高覆盖、宽方位、大偏移距观测系统,提高地震资料采集品质;(2)形成以微测井约束层析静校正、保真保幅高分辨率处理、全方位角度域叠前深度偏移为主的复杂构造带地震成像技术,提高地震资料深层成像质量;(3)利用高精度重磁电资料提取地质结构、断裂等信息,结合地震资料精细解释,落实构造细节和断裂特征;(4)基于模型正演和单井储层地震精细标定,优选属性预测储层分布。运用上述配套技术,新发现川西北部地区1223 km~2大型构造—岩性复合圈闭,双鱼石—江油地区整体处于构造高带,双鱼石以南地区栖霞组台缘带白云岩储层连片发育。结论认为,该配套技术较好地解决了该区复杂构造带圈闭落实和薄储层预测等难题,明确了勘探方向,为井位部署提供了技术支撑,加快了深层海相碳酸盐岩气藏勘探开发示范工程的建设步伐。  相似文献   
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