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371.
An in-situ large-scale underground blast test program was conducted to investigate stress wave characteristics inside the medium, at the soil-rock interface and on the soil ground surface. The stress wave measurements were made through a vertical borehole and a horizontal borehole inside the rock mass, and along several horizontal lines arranged at the rock-soil interface and on the soil surface. Three different charge weights of 0.5, 2.5 and 10 t with loading densities of 0.5, 2.5 and 10 kg/m3, respectively, were used in the detonation. The measured stress wave time histories and their characteristic parameters, such as peak particle velocity (PPV) and peak particle acceleration (PPA), as well as the principal frequency (PF) at different locations are presented and analyzed in this paper. The results are also compared with those recorded from small-scale tests in a previous study and those from some other researchers, and the pertinent scale effects are discussed by observing differences of the stress wave intensities between the small-scale and the large-scale tests.Received: 18 November 2002, Accepted: 8 July 2003, Published online: 8 October 2003 相似文献
372.
“Geomechatronics” is a technical field in which “Geotechniques” is fused with “Mechatronics” that is the technical field to promote the automatic control of machines by using the electronics. In the field of “Geomechatronics”, a construction machine, which treats geotechnical materials such as soil and rock, automatically evaluates the properties and conditions of the ground and determines the optimum controlling method of itself for the ground with the base of the machine–ground interaction. Some researches for practical use in the field of geomechatronics are introduced, and then the progressing view of this research and technical filed is explained in this paper. 相似文献
373.
K. Nagayama Y. Kotsuka T. Kajiwara T. Nishiyama S. Kubota M. Nakahara 《Shock Waves》2007,17(3):171-183
We have studied pulse laser ablation of ground glass surface. Ablation process in air and in vacuum has been observed by high
speed framing camera. Burst of small fragments of glass has been observed in the present experiment, when ground glass surface
is laser ablated through glass plate from rear side. Production of macro particles by laser ablation is an inherent characteristic
of ground glass, and no similar phenomena have been observed in case of ablation of other transparent materials. By using
ns-duration Nd:YAG laser of 100–400 mJ/pulse, observed maximum particle velocity ranges from 0.5 to 1.5 km/s. In order to
understand the particle generation process, scanning electron micrograph observation of the ground surface in the region of
no laser irradiation and also in the damaged region, has been made. Cleavage surface structure has been evidenced in the damaged
surface area, which stems from plenty of micro cracks covering the virgin glass surface. Effects of surface roughness on the
particle generation were studied by using ground glass of quartz with different surface roughness. Produced glass particles
were captured in vacuum by a polymethylmetacrylate (PMMA) plate. Size distribution was obtained by analysing the trapped particles
on the PMMA plate and revealed that most probable particles size has almost no dependence on the initial surface roughness.
Finally, we applied the phenomena to ignite pentaerithritoltetranitrate (PETN) powder explosive, and succeeded in igniting
(PETN) powder only by laser ablation of ground glass.
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利用多年冻土区昆仑山隧道2#冲沟帷幕注浆的机会,将注浆孔当作测试孔,测试每个孔的水位和孔温。通过测试孔水位、孔温和注浆量变化分析,判断2#冲沟融区发育特征,得出2#冲沟沟底的融化深度远大于通常的冻土上限;阳坡地温高于阴坡地温;在2#冲沟段,昆仑山隧道中心线左右至少7m范围内为融化区,融区深度在隧底25m以下;阳坡地层的孔隙率高于阴坡孔隙率,沟底岩层与地表有较为畅通的地下水流通道,沟底地下水渗流通道明显优于两侧山坡,沟心纵断面位置附近存在至少一条未被冻结的地下水通道,且该通道的埋置深度至少可达1730m,为昆仑山隧道渗漏水病害治理提供依据。 相似文献
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This paper reviews methods currently used to predict the pressure exerted by a wheeled vehicle on the ground. It describes a programme of experiments designed to measure the pressure at a certain depth in a soil mass, the surface of which is traversed by a number of different vehicles in a range of loading conditions. Methods for inferring the surface pressure from underground measurements are described and compared. The inferred surface pressures are then compared with predicted values. A discussion is given on the usefulness and validity of ground pressure characterisation for wheeled vehicles. 相似文献