全文获取类型
收费全文 | 32915篇 |
免费 | 5177篇 |
国内免费 | 2948篇 |
专业分类
电工技术 | 5723篇 |
技术理论 | 5篇 |
综合类 | 3588篇 |
化学工业 | 4399篇 |
金属工艺 | 1290篇 |
机械仪表 | 1998篇 |
建筑科学 | 1794篇 |
矿业工程 | 607篇 |
能源动力 | 1506篇 |
轻工业 | 942篇 |
水利工程 | 504篇 |
石油天然气 | 730篇 |
武器工业 | 367篇 |
无线电 | 4273篇 |
一般工业技术 | 4517篇 |
冶金工业 | 783篇 |
原子能技术 | 429篇 |
自动化技术 | 7585篇 |
出版年
2024年 | 256篇 |
2023年 | 793篇 |
2022年 | 1042篇 |
2021年 | 1301篇 |
2020年 | 1575篇 |
2019年 | 1474篇 |
2018年 | 1268篇 |
2017年 | 1519篇 |
2016年 | 1520篇 |
2015年 | 1522篇 |
2014年 | 2041篇 |
2013年 | 2267篇 |
2012年 | 2199篇 |
2011年 | 2416篇 |
2010年 | 1786篇 |
2009年 | 1729篇 |
2008年 | 1887篇 |
2007年 | 2048篇 |
2006年 | 1901篇 |
2005年 | 1613篇 |
2004年 | 1352篇 |
2003年 | 1141篇 |
2002年 | 1033篇 |
2001年 | 853篇 |
2000年 | 739篇 |
1999年 | 676篇 |
1998年 | 448篇 |
1997年 | 457篇 |
1996年 | 377篇 |
1995年 | 319篇 |
1994年 | 299篇 |
1993年 | 268篇 |
1992年 | 189篇 |
1991年 | 143篇 |
1990年 | 123篇 |
1989年 | 87篇 |
1988年 | 72篇 |
1987年 | 39篇 |
1986年 | 37篇 |
1985年 | 22篇 |
1984年 | 32篇 |
1983年 | 26篇 |
1982年 | 28篇 |
1981年 | 15篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1960年 | 5篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
V. V. Tcherdyntsev S. D. Kaloshkin A. I. Salimon E. A. Leonova I. A. Tomilin J. Eckert F. Schurack V. D. Rogozin S. P. Pisarev Yu. P. Trykov 《Materials and Manufacturing Processes》2002,17(6):825-841
Al-Cu-Fe alloys were prepared from elemental powders in a high-energy planetary ball mill. A sequence of solid state reactions resulting in quasicrystal (QC) phase formation takes place during heating of the as-milled powder. These reactions were studied by both differential scanning calorimetry and x-ray diffraction methods. Mechanically alloyed powders were consolidated by cold and hot pressing, as well as by explosive compaction. After annealing at sufficiently high temperatures, the consolidated samples are single-phase QC, except the ones consolidated by explosion. The high reactivity of the as-milled alloys causes the appearance of high porosity of the consolidated samples after the annealing. 相似文献
42.
43.
Shunsuke Ohashi 《Electrical Engineering in Japan》2005,150(1):71-77
Magnetic bearing using pinning force of a permanent magnet and a high‐temperature superconductor has been developed. Additional permanent magnet is introduced to increase the levitation force of the magnetic bearing. In this hybrid magnetic bearing system, levitation force is mainly given by the repulsive force of the permanent magnets, and stability for the lateral direction is given by pinning force of the superconductor. The experimental device is developed. A ring‐type superconductor and a bulk one are examined. Levitation characteristics of the hybrid magnetic bearing are measured. The bulk superconductor shows better characteristics of both levitation and lateral stability than the ring one. Levitation force of the hybrid system becomes about twice as large as that of the nonhybrid one. Although, the repulsive force of the permanent magnet decreases the lateral stability of the system, its influence becomes small by choosing an adequate position of the permanent magnets and the superconductor. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 71–77, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10350 相似文献
44.
Kotaro Matsuuchi Tadashi Fukami Nobuyuki Naoe Ryoichi Hanaoka Shinzo Takata Toshio Miyamoto 《Electrical Engineering in Japan》2005,150(2):43-49
This paper presents a method of predicting the steady‐state performance of a new hybrid‐excitation synchronous machine (HESM) theoretically. The field pole of this HESM is axially divided into two parts; one is an excitation part and the other a permanent‐magnet (PM) part. A nonlinear equivalent circuit, which can include the saliency of the rotor and the magnetic saturation due to the iron core, is derived. Based on this equivalent circuit, the steady‐state performance of the HESM is calculated, and the results are confirmed through experiments. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 43–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20033 相似文献
45.
This paper proposed a novel hybrid probabilistic network, which is a good tradeoff between the model complexity and learnability
in practice. It relaxes the conditional independence assumptions of Naive Bayes while still permitting efficient inference
and learning. Experimental studies on a set of natural domains prove its clear advantages with respect to the generalization
ability. 相似文献
46.
针对回转窑在运行过程中窑体变形的情况开发了一种监测与报警系统。完成了系统的前向通道设计、单片机与PC机的串行通讯设计和报警显示。 相似文献
47.
The exact magnetization pattern of magnetic films close to a spin-reorientation transition is difficult to analyze due to the intrinsically three-dimensional (3d) variation of the orientation of the local magnetization. We present a technique how this can be performed, based on the analysis of high quality 2d polarization maps from a single scanning electron microscope with polarization analysis (SEMPA) measurement with tilted sample. The key tool is the statistical distribution of all occurring polarization doublets, visualized in a 2d histogram plot. From the shape of the distribution the type of transition—canted-phase, or coexisting phases—can be inferred. For the canted-phase state, the canting angle can be accurately determined from geometrical considerations. With help of the histogram the image data can be analyzed and the three components of the magnetization can be calculated for most points of the image. For a Co/Pt multilayer film we found a cone state. The magnetization forms a complex pattern consisting of out-of-plane domains while the in-plane magnetization shows a maze pattern. 相似文献
48.
John Tsinias 《Systems & Control Letters》1991,17(1)
In this paper we generalize the Vidyasagar's well known theorem on the local stabilizability problem of nonlinear systems using state detection [11]. Our purpose is to prove that if a system is weakly detectable and stabilizable by means of a continuous state feedback u = γ(x), for which no differentiability assumption is imposed, then the system is also stabilized by the law u = γ(z), where z is the output of a weak detector for the state x. The result above is applicable to several cases not covered by other works. 相似文献
49.
XiaYinshui A.E.A.Almaini WuXunwei 《电子科学学刊(英文版)》2003,20(3):194-201
Using state assignment to minimize power dissipation and area for finite state machines is computationally hard.Most of published results show that the reduction of switching activity often trades with area penalty.In this paper,a new approach is proposed.Experimental results show a significant reduction of switching activity without area penalty compared with previous publications. 相似文献
50.
Docherty Nancy M.; Cohen Alex S.; Nienow Tasha M.; Dinzeo Thomas J.; Dangelmaier Ruth E. 《Canadian Metallurgical Quarterly》2003,112(3):469
This study examined the degree to which different types of communication disturbances in the speech of 48 schizophrenia patients and 28 controls were variable and state related versus stable and traitlike. Clinically rated formal thought disorder and 5 types of referential disturbance showed substantial stability within participants over time. The sixth type of referential disturbance, the vague reference, was not stable over time. Formal thought disorder was associated with the severity of core psychotic symptoms in patients, whereas referential disturbances showed little or no association with positive or negative symptom severity. Furthermore, changes in psychotic symptoms over time were accompanied by corresponding changes in formal thought disorder but not referential disturbances. These results support the idea that some types of referential disturbances are traitlike and may be reflective of vulnerability as well as manifest illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献