全文获取类型
收费全文 | 1321篇 |
免费 | 36篇 |
专业分类
电工技术 | 118篇 |
综合类 | 2篇 |
化学工业 | 416篇 |
金属工艺 | 34篇 |
机械仪表 | 39篇 |
建筑科学 | 29篇 |
能源动力 | 79篇 |
轻工业 | 98篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
无线电 | 45篇 |
一般工业技术 | 246篇 |
冶金工业 | 117篇 |
原子能技术 | 47篇 |
自动化技术 | 81篇 |
出版年
2023年 | 7篇 |
2022年 | 13篇 |
2021年 | 31篇 |
2020年 | 10篇 |
2019年 | 22篇 |
2018年 | 28篇 |
2017年 | 17篇 |
2016年 | 25篇 |
2015年 | 19篇 |
2014年 | 44篇 |
2013年 | 79篇 |
2012年 | 48篇 |
2011年 | 101篇 |
2010年 | 51篇 |
2009年 | 74篇 |
2008年 | 73篇 |
2007年 | 58篇 |
2006年 | 45篇 |
2005年 | 38篇 |
2004年 | 35篇 |
2003年 | 48篇 |
2002年 | 46篇 |
2001年 | 29篇 |
2000年 | 30篇 |
1999年 | 32篇 |
1998年 | 61篇 |
1997年 | 39篇 |
1996年 | 36篇 |
1995年 | 32篇 |
1994年 | 18篇 |
1993年 | 19篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 5篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 22篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 4篇 |
排序方式: 共有1357条查询结果,搜索用时 15 毫秒
91.
In general, experimentally measured fields such as moiré-interferometry fringes contain various errors associated with the
measurement and subsequent data analysis. Moreover, the measured displacement field does not necessarily satisfy the equilibrium
equation in solid mechanics, especially when the measurement errors are involved. First, a variational principle minimizing
the experimental measurement errors is derived to overcome such difficulties. Next, on the basis of this variational principle,
a new hybrid moiré-interferometry and finite-element method is developed. Concepts of restoration energy and restoration force
are also presented in the context of the present hybrid method. The present hybrid method demonstrates automatic detection
and elimination of the measurement errors and smooth visualization of stress contours. The present hybrid method automatically
achieves the path independence of the J integral, restoring the path-dependence caused by the measurement errors. 相似文献
92.
The electrical conduction and microstructure in Y-doped ceria and Ho-doped ceria were investigated. Visible differences between the two doped ceria were observed. The plots of conductivity of Y-doped ceria are well fit to the Arrhenius behavior, while curvature and kinks were observed on the plots of Ho-doped ceria. Such deviation from the Arrhenius behavior could be related to the existence of precipitates in Ho-doped ceria. It indicates that the electrolytic conductivity of doped ceria could be significantly influenced by microstructure features. 相似文献
93.
This paper deals with a three-dimensional stress analysis of adhesive butt joints of similar solid cylinders subjected to external tensile loads. Similar adherends and an adhesive bond are replaced with finite solid cylinders in the analysis. Stress distributions on adhesive joints are analyzed strictly by using the three-dimensional theory of elasticity. The effects of stiffness, thickness and Poisson's ratio of the adhesive bonds and of external load distribution on the normal and the shear stress distributions are shown by numerical calculations. In addition, the analytical result is compared with the result obtained by F.E.M. It is seen that they are in fairly good agreement. 相似文献
94.
In Japan, the research and development on the High Temperature Gas-cooled Reactors (HTGRs) had been carried out for more than fifteen years since 1969 as the multi-purpose Very High Temperature gas-cooled Reactor (VHTR) program for direct utilization of nuclear process heat such as nuclear steel making. Recently, reflecting the change of the social and energy situation and with less incentives for industries to introduce such in the near future, the JAERI changed the program to a more basic ‘HTTR program’ to establish and upgrade the HTGR technology basis.The HTTR is a test reactor with a thermal output of 30 MW and reactor outlet coolant temperature of 950°C, employing a pin-in-block type fuel block, and has the capability to demonstrate nuclear process heat utilization using an intermediate heat exchanger. Since 1986 a detailed design has been made, in which major systems and components are determined in line with the HTTR concept, paying essential considerations into the design for achieving the reactor outlet coolant temperature of 950°C. The safety review of the Government started in February 1989. By request of the Science and Technology Agency the Reactor Safety Research Association reviewed the safety evaluation guideline, general design criteria, design code and design guide for the graphite and the high-temperature structure of the HTTR.The installation permit of the HTTR was issued by the Government in November 1990. 相似文献
95.
The effect of hydroperoxide in breads on antigen-antibody reaction against IgE was examined. We compared the antigen-antibody reaction against IgE between dough including hydroperoxide and that not including hydroperoxide. Crude proteins extracted from the dough including hydroperoxide showed weak antigen-antibody reaction on allergic tests such as ring precipitin test with human-specific IgE, and the IgE binding activity on ELISA. In contrast, the dough without hydroperoxide showed antigen-antibody reaction. The crude proteins extracted from the dough with hydroperoxide or without hydroperoxide were applied by affinity chromatography of trypsin-immobilized chitin. Then proteins having affinity were recovered. The recovered proteins were separated by SDS-PAGE. Each protein was examined for the IgE binding activity on ELISA. The IgE binding activity of baked bread was studied as well. Crude proteins of baked bread made from dough including hydroperoxide showed weaker IgE binding activity on ELISA than proteins of baked bread made from dough without hydroperoxide. Those results suggested that addition of hydroperoxide into dough affects on antigen activation. 相似文献
96.
In this work, a failure criterion applicable to large strain Finite Element Analysis (FEA) results was proposed in order to predict both the fracture mode (collapse or cracking) and the limit bending load of wall-thinned straight pipes. This work was motivated from the recent experimental results of Tsuji and Meshii (2011); that is, fracture mode is not always collapse, and the fracture mode affects the limit bending load. The key finding in comparing their test results and a detailed large strain FEA results was that the Mises stress distribution at the limit bending load of a flawed cylinder was similar to that of a flawless cylinder; specifically, in case of collapse, the Mises stress exceeded the true yield stress of a material for the whole “volume” of a cylinder with a nominal wall thickness. Based on this finding, a failure criterion applicable to large strain FEA results of wall-thinned straight pipes under a bending load that can predict both fracture mode and limit bending load was proposed and was named the Domain Collapse Criterion (DCC). DCC predicts the limit bending load as the lower value of either the McFEA, which is the load at which the Mises stress exceeds the true yield strength of a straight pipe for the whole “volume” with a nominal wall thickness (fracture mode: collapse), or the McFEAb, which is the load at which the Mises stress in a section of the flaw ligament exceeds the true tensile stress (fracture mode: cracking). The results showed that the DCC could predict the fracture mode appropriately and the experimental limit bending load fundamentally on the conservative side within a maximum 20% difference regardless of the fracture mode. Another advantage of the DCC is that it uses the true yield and true tensile strength as the critical strength of the material and not the ambiguous flow strength. 相似文献
97.
Hydrolysis degradation of a set of drawn poly(lactic acid) (PLA) fibers was induced by an accelerated weathering test, radiating ultraviolet (UV) light under a certain temperature and humidity. The fine features of the transient behavior of the PLA fibers were captured by near-infrared (NIR) hyperspectral imaging. The PLA fibers showed a gradual decrease in mechanical property (e.g., tensile strength), indicating hydrolysis degradation. Thus, the detailed analysis of the spectral variation, in turn, offers useful information on the molecular-level degradation behavior of the drawn PLA fibers. The variation of the spectral intensity as well as band position shift of the crystalline band of PLA was analyzed. The spectral intensity of the crystalline band of PLA showed gradual decrease, suggesting the decrease in molecular weight induced by the hydrolysis degradation. In addition, the crystalline band also exhibited a coinciding shift to the lower wavenumber direction with the weathering test, revealing cleavage-induced crystallization of the PLA samples. Consequently, the hydrolysis degradation induced by the weathering test substantially accelerates predominant degradation of the amorphous structure of the PLA and such variation of the molecular structure, in turn, brings less ductility to the PLA fiber. 相似文献
98.
In this paper, an image processing strain measurement system was extended so that fracture behavior of wall-thinned pipes, such as out of plane and large plastic deformation observed in bulging, can be evaluated by the system. Regular grids with nominal size of 10 mm × 10 mm were marked on 100A carbon steel pipes and the images taken with 6 CCD cameras of 15 million pixels were correlated to achieve resolution of 0.3% strain. Strain of the cylinder's outer surface was evaluated by (1) modeling the grids as a cylindrical shell, (2) measuring deformation of the grid on a projected plane, and (3) applying an updated Lagrangian method. The validity of the system was confirmed by applying the proposed system to the burst tests of a wall-thinned cylinder. In addition, the system measured the non-uniform strain distribution that explained the unexpected cracking location. 相似文献
99.
In this paper, a limit bending moment equation applicable to all types of planar and non-planar flaws in wall-thinned straight pipes under bending was proposed. A system to rationally classify the planar/non-planar flaws in wall-thinned pipes was suggested based on experimental observations focused on the fracture mode. The results demonstrate the importance of distinguishing between axial and circumferential long flaws in wall-thinned pipes. 相似文献
100.