全文获取类型
收费全文 | 1872篇 |
免费 | 82篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 75篇 |
综合类 | 3篇 |
化学工业 | 468篇 |
金属工艺 | 38篇 |
机械仪表 | 42篇 |
建筑科学 | 37篇 |
矿业工程 | 1篇 |
能源动力 | 73篇 |
轻工业 | 167篇 |
水利工程 | 14篇 |
石油天然气 | 2篇 |
无线电 | 139篇 |
一般工业技术 | 299篇 |
冶金工业 | 356篇 |
原子能技术 | 81篇 |
自动化技术 | 163篇 |
出版年
2023年 | 26篇 |
2022年 | 46篇 |
2021年 | 79篇 |
2020年 | 40篇 |
2019年 | 47篇 |
2018年 | 65篇 |
2017年 | 47篇 |
2016年 | 68篇 |
2015年 | 52篇 |
2014年 | 53篇 |
2013年 | 106篇 |
2012年 | 97篇 |
2011年 | 114篇 |
2010年 | 65篇 |
2009年 | 69篇 |
2008年 | 82篇 |
2007年 | 63篇 |
2006年 | 48篇 |
2005年 | 45篇 |
2004年 | 49篇 |
2003年 | 52篇 |
2002年 | 35篇 |
2001年 | 29篇 |
2000年 | 25篇 |
1999年 | 31篇 |
1998年 | 151篇 |
1997年 | 93篇 |
1996年 | 59篇 |
1995年 | 24篇 |
1994年 | 24篇 |
1993年 | 30篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 12篇 |
1974年 | 2篇 |
1972年 | 3篇 |
排序方式: 共有1958条查询结果,搜索用时 15 毫秒
61.
62.
Lam Vu Phan Sang Le Duy-Dinh Duong Duc Anh Satoh Shin’ichi 《Multimedia Tools and Applications》2017,76(5):7041-7065
Multimedia Tools and Applications - Violent scenes detection (VSD) is a challenging problem because of the heterogeneous content, large variations in video quality, and complex semantic meanings of... 相似文献
63.
The goal of our study is to develop a system for walking on a step using a wearable robot. Our system consists of (1) sensing of a step from the movement of the walker, (2) detection of the foot placement state related to the step, and (3) generation of gait patterns of climbing and stepping down for the step. In the generation of gait patterns for the step, toe trajectories are generated according to the height of the step to avoid collision of the swinging leg with the step. The hip trajectory is generated by an optimization technique that minimizes the sum of the joint angular jerk of the robot subject to constraints on the hip position and the velocity at toe liftoff. Each joint angle trajectory is calculated from the generated trajectories by means of inverse kinematic equations. We investigated the feasibility of the proposed sensor and control systems for two steps with different heights. 相似文献
64.
Ba2(Fe1?xInx)2O5 was prepared by a solid‐state reaction under a N2 flow. It was revealed that the solid solutions had a cubic perovskite structure with disordered oxygen vacancies at room temperature. Thermogravimetry and X‐ray diffraction measurements revealed that Ba2(Fe1?xInx)2O5 can reversibly react with CO2. It was found that the equilibrium temperature of the reaction could be controlled by preparing solid solution. 相似文献
65.
66.
Wonsang Kwon Yecheol Rho Kensuke Kamoshida Kyung Ho Kwon Youn Cheol Jeong Jonghyun Kim Hideki Misaka Tae Joo Shin Jehan Kim Kwang‐Woo Kim Kyeong Sik Jin Taihyun Chang Heesoo Kim Toshifumi Satoh Toyoji Kakuchi Moonhor Ree 《Advanced functional materials》2012,22(24):5194-5208
Low‐temperature anionic ring‐opening homopolymerizations and copolymerizations of two glycidol derivatives (allyl glycidyl ether (AGE) and ethoxyethyl glycidyl ether (EEGE)) are studied using a metal‐free catalyst system, 3‐phenyl‐1‐propanol (PPA) (an initiator) and 1‐tert‐butyl‐4,4,4‐tris(dimethylamino)‐2,2‐bis[tris‐(dimethylamino)phosphoranylidenamino]‐2Λ5,4Λ5‐catenadi(phosphazene) (t‐Bu‐P4) (a promoter) in order to obtain well‐defined functional linear polyethers and diblock copolymers. With the aid of the catalyst system, AGE is found to successfully undergo anionic ring‐opening polymerization (ROP) even at room temperature (low reaction temperature) without any side reactions, producing well‐defined linear AGE‐homopolymer in a unimodal narrow molecular weight distribution. Under the same conditions, EEGE also undergoes polymerization, producing a linear EEGE‐homopolymer in a unimodal narrow molecular‐weight distribution. In this case, however, a side reaction (i.e., chain‐transfer reaction) is found to occur at low levels during the early stages of polymerization. The chemical properties of the monomers in the context of the homopolymerization reactions are considered in the design of a protocol used to synthesize well‐defined linear diblock copolyethers with a variety of compositions. The approach, anionic polymerization via the sequential step feed of AGE and EEGE as the first and second monomers, is found to be free from side reactions at room temperature. Each block of the obtained linear diblock copolymers undergoes selective deprotection to permit further chemical modification for selective functionalization. In addition, thermal properties and structures of the polymers and their post‐modification products are examined. Overall, this study demonstrates that a low‐temperature metal‐free anionic ROP using the PPA/t‐Bu‐P4 catalyst system is suitable for the production of well‐defined linear AGE‐homopolymers and their diblock copolymers with the EEGE monomer, which are versatile and selectively functionalizable linear aliphatic polyether platforms for a variety of post‐modifications, nanostructures, and their applications. 相似文献
67.
Hiroyuki Kuramae Yuki Ikeya Hideo Morimoto 《International Journal of Mechanical Sciences》2010,52(2):183-197
A multi-scale parallel finite element (FE) procedure based on the crystallographic homogenization method was applied to the LDH sheet formability test analysis. For the multi-scale structure, two scales are considered. One is a microscopic polycrystal structure and the other is a macroscopic elastic plastic continuum. The analysis code can predict the formability of sheet metal in macro-scale, simultaneously the crystal texture and hardening evolutions in the micro-scale (Nakamachi E et al. Int J Plasticity 2007;23:450-8). Since huge computation time is required for the nonlinear dynamic multi-scale FE analysis, parallel computing technique based on domain partitioning of FE model for macro-continuum is introduced into the multi-scale code using the message passing interface (MPI) library and PC cluster (Kuramae H et al. In: Proceedings of the eighth international conference on computational plasticity, Part 1, 2005. p. 622-5). The explicit time stepping solution scheme in the nonlinear multi-scale FE dynamic problem is well-suited for parallel computing on distributed memory environment such as PC cluster because solving simultaneous equation is not required. We measured crystal morphologies of four automotive sheet metals, aluminum alloy sheet metals A6022-T43 and A5182-O, an asymmetrically rolled aluminum alloy sheet metal A6022-ASR, and mild steel HC220YD, by using the scanning electron microscope (SEM) with electron back scattered diffraction (EBSD) analyses, and defined a three-dimensional representative volume element (RVE) of micro polycrystal structure, which satisfy the periodicity condition of crystal orientation distribution. We evaluate not only macroscopic formability of the automotive sheet metals by the multi-scale LDH test analysis, but also microcrystalline texture evolution during plastic deformation. Furthermore, a relationship between the macroscopic formability and the microcrystal texture evolution was discussed through looking at multi-scale FE results. It is concluded that the mild steel HC220YD was the highest formability than the aluminum alloy sheet metals because of remaining and generating the γ-fiber texture, such as {1 1 1}〈1 1 0〉-{1 1 1}〈1 1 2〉 orientations, during plastic deformation. 相似文献
68.
Yu Takanashi Yuki OrikasaMasato Mogi Masatsugu OishiHaruno Murayama Kenji SatoHisao Yamashige Daiko TakamatsuTakahiro Fujimoto Hajime TanidaHajime Arai Toshiaki OhtaEiichiro Matsubara Yoshiharu UchimotoZempachi Ogumi 《Journal of power sources》2011,196(24):10679-10685
Solid electrolyte interface (SEI) films formed on Li1−xCoO2 electrodes were observed with hard X-ray photoelectron spectroscopy (HX-PES). This paper particularly focuses on film thickness estimation using HX-PES with theoretical calculation. The validity of the calculation was proven by experiments using model SEI films. The native film formed on a LiCoO2 composite electrode was estimated to be LiF with its thickness of 5 nm. Formation of Co (II) species on top of LiCoO2 was also indicated. Storage of the electrode at 60 °C brought about considerable film growth (30-40 nm) with carbonate compounds formation. SEI film changes during charging of the LiCoO2 electrode were also examined. The main component in the film was deduced to be LiF or a kind of fluorite, with its thickness decreased during charging. The SEI formation mechanisms are also elucidated. 相似文献
69.
70.
Prepolymerizations of 4,4′‐bismaleimidodiphenylmethane (BMI), diallyl isocyanurate (DAIC), and melamine (ML) at 160–170°C and subsequent compression molding at 200–280°C yielded cured BMI/DAIC/ML resins with feed molar ratios of 4/1/1, 3/1/1, and 2/1/1 (BMI‐DAIC‐ML411, 311, and 211). Similarly, cured BMI/DAIC 1/1 and BMI/ML 3/1 resins (BMI‐DAIC11 and BMI‐ML31) were prepared. The FT‐IR analysis revealed that the maleimide and allyl groups were almost consumed for all the cured resins, and the hydrogen bonding interaction became stronger with decreasing BMI contents for BMI‐DAIC‐MLs. Based on the cured structures elucidated from the FT‐IR result, the numbers of multiple hydrogen bonds and cross‐linking covalent bonds (NMHB and NCB), and total cross‐linking bond energy (ETB) were evaluated to be 0, 7.92, and 618 for BMI‐DAIC‐ML411, 0.71, 7.81, and 627 for BMI‐DAIC‐ML311, and 0.95 mol kg?1, 7.61 mol kg?1, and 617 kcal kg?1 for BMI‐DAIC‐ML211, respectively. A higher order of glass transition and 5% weight loss temperatures for BMI‐DAIC‐MLs was 411 > 311 > 211 in accordance with a higher order of NCB. BMI‐DAIC‐MLs displayed a weak tan δ peak at 70–150°C due to dissociation of the hydrogen bonds. The flexural strength and modulus of BMI‐DAIC‐ML311 were higher than those of BMI‐DAIC‐ML411 in accordance with the difference of ETB. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43121. 相似文献