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121.
122.
镀镍渗硼层的抗热震及抗高温氧化性能 总被引:2,自引:0,他引:2
研究了45钢镀镍渗硼层的抗热震能力及抗高温氧化性能。研究结果表明,镀镍渗硼层的硼化物齿间存在γ-(Fe,Ni)固溶体,渗层表面含镍量较高,渗层致密、光滑、可明显改善单一渗硼层的抗热震及高温氧化性能。 相似文献
123.
对于现代汽车而言,最佳的点火提前角不仅要保证发动机的动力性和燃油经济性都达到最佳值,还必须保证排放性最好.介绍了点火提前角影响因素,提出了对点火提前角进行控制的方法,从而使发动机的动力性和经济性达到最优. 相似文献
124.
Xinghua Zhang Jun Yang Jiqiang Ma Junying Hao Qinling Bi Yongmin Liang Weimin Liu 《Tribology Letters》2012,45(1):109-116
The tribological behaviour of Fe–28Al–5Cr and its composites containing 15, 25 and 50 wt% TiC (corresponding to 19.3, 31.2
and 57.6 vol%), produced by hot-pressing process, was investigated under liquid paraffine lubrication against an AISI 52100
steel ball in ambient environment at varied applied loads and sliding speeds. It was found that the wear resistance increased
and friction coefficient decreased with increasing of TiC content. The coefficients of friction are in the range of 0.09–0.14
at the given testing conditions. The wear rates of all the materials except the 50% composite are on the order of 10−6–10−5 mm3 m−1, the wear rate for the 50% composite is too low to quantify under the two sliding conditions, (50 N, 0.04 m/s) and (100 N,
0.02 m/s). The wear rates of all the materials increase as applied load increases and the increasing extent diminishes with
the increase of TiC content, but first increase slightly and then nearly remains steadiness with increasing sliding speed.
The 50 wt% composite has wear resistance about 7–20 times better than pure Fe–28Al–5Cr at different sliding parameters. The
enhanced wear resistance by TiC addition is attributed to the high hardness of the composites, as well as support of the oil
lubrication film/layer by the hard TiC phase. The worn surfaces of all the materials are analyzed by a scanning electron microscope.
The dominant wear mechanism of the Fe–28Al–5Cr and 15% composite is grooving and flaking-off, but those of the 25 and 50%
composites are mainly shallow grooving. 相似文献
125.
126.
Harianto Rahardjo Nguyen Cong Thang Yongmin Kim Eng-Choon Leong 《Soils and Foundations》2018,58(3):534-546
Transient process of water flow changes the equilibrium conditions of an unsaturated soil, resulting in volume change of a soil. The volume change alters the hydraulic properties of the soil and thus influences the transient process of water flow through the soil. Therefore, the interactive processes between stress-strain behavior and pore-water pressure are the primary processes affecting the mechanical behavior of unsaturated soils. This paper presents coupled elasto-plastic constitutive equations for unsaturated compacted kaolin under consolidated drained and shearing-infiltration conditions. The study focused on the development of the suction increase (SI) yield curve that incorporates changes in matric suction during transient processes. In addition, the relationship of change in specific water volume with respect to net mean stress and matric suction was also proposed by incorporating the hysteresis of soil-water characteristic curve. The simulated results by the proposed constitutive model were compared with those obtained from isotropically consolidated drained tests and shearing infiltration tests of compacted kaolin to verify the proposed model. The simulated results are in close agreement with the experimental results. 相似文献
127.
随着城镇住宅建筑不断增加,对住宅空调的需求量也急剧增长。目前,中国住宅空调是以电力空调为主,住宅空调间断性负荷是拉大电力峰谷差、造成电力短缺的重要原因之一。我国天然气资源丰富,并且举世瞩目的“西气东输”工程已启动,因此发展燃气空调是很好的选择。燃气空调就是直接使用燃气作为能源的空调,具有保护环境、平衡燃气峰谷、改善电力负荷率及能源利用效率高的优点,近年来在国内外均得到了较快的发展。本文在介绍了各种燃气空调方案的基础上,提出了我国燃气空调发展的建议。 相似文献
128.
叙述了仕嘉SOHO楼的基础设计、抗震设计。分析了倾斜部分的受力特征。并介绍了倾斜型钢混凝土构件的构造措施。 相似文献
129.
随着数字技术在通信系统中的广泛应用,数字集群通信系统逐渐成为专用通信市场主流。对陆上集群无线系统(TETRA)中的数字集群通信系统的物理层协议进行了分析,提出并设计了基带信号处理的单芯片解决方案。该芯片包含嵌入式ARM9内核,兼容多种卷积方式的信道编解码和兼容多种速率的GMSK调制解调等模块,能够完成从TETRA协议处理到调制解调的全部基带处理功能,具有精度可调,应用灵活的特点,适合公安、武警、消防等专用安全领域的数字集群应用。该芯片电路通过了FPGA原型验证并已应用于TETRA集群通信系统。 相似文献
130.
Yongji Gong Gonglan Ye Sidong Lei Gang Shi Yongmin He Junhao Lin Xiang Zhang Robert Vajtai Sokrates T. Pantelides Wu Zhou Bo Li Pulickel M. Ajayan 《Advanced functional materials》2016,26(12):2009-2015
The emergence of semiconducting transition metal dichalcogenide (TMD) atomic layers has opened up unprecedented opportunities in atomically thin electronics. Yet the scalable growth of TMD layers with large grain sizes and uniformity has remained very challenging. Here is reported a simple, scalable chemical vapor deposition approach for the growth of MoSe2 layers is reported, in which the nucleation density can be reduced from 105 to 25 nuclei cm?2, leading to millimeter‐scale MoSe2 single crystals as well as continuous macrocrystalline films with millimeter size grains. The selective growth of monolayers and multilayered MoSe2 films with well‐defined stacking orientation can also be controlled via tuning the growth temperature. In addition, periodic defects, such as nanoscale triangular holes, can be engineered into these layers by controlling the growth conditions. The low density of grain boundaries in the films results in high average mobilities, around ≈42 cm2 V?1 s?1, for back‐gated MoSe2 transistors. This generic synthesis approach is also demonstrated for other TMD layers such as millimeter‐scale WSe2 single crystals. 相似文献