全文获取类型
收费全文 | 1858篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 23篇 |
综合类 | 1篇 |
化学工业 | 262篇 |
金属工艺 | 51篇 |
机械仪表 | 29篇 |
建筑科学 | 55篇 |
矿业工程 | 5篇 |
能源动力 | 18篇 |
轻工业 | 155篇 |
水利工程 | 10篇 |
石油天然气 | 2篇 |
无线电 | 192篇 |
一般工业技术 | 325篇 |
冶金工业 | 594篇 |
原子能技术 | 23篇 |
自动化技术 | 141篇 |
出版年
2022年 | 20篇 |
2021年 | 17篇 |
2019年 | 15篇 |
2018年 | 24篇 |
2017年 | 27篇 |
2016年 | 20篇 |
2015年 | 17篇 |
2014年 | 26篇 |
2013年 | 35篇 |
2012年 | 53篇 |
2011年 | 60篇 |
2010年 | 53篇 |
2009年 | 46篇 |
2008年 | 62篇 |
2007年 | 74篇 |
2006年 | 40篇 |
2005年 | 38篇 |
2004年 | 38篇 |
2003年 | 44篇 |
2002年 | 35篇 |
2001年 | 44篇 |
2000年 | 42篇 |
1999年 | 54篇 |
1998年 | 187篇 |
1997年 | 126篇 |
1996年 | 93篇 |
1995年 | 52篇 |
1994年 | 44篇 |
1993年 | 49篇 |
1992年 | 23篇 |
1991年 | 21篇 |
1990年 | 24篇 |
1989年 | 22篇 |
1988年 | 20篇 |
1987年 | 27篇 |
1986年 | 22篇 |
1985年 | 23篇 |
1984年 | 17篇 |
1983年 | 18篇 |
1982年 | 10篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 22篇 |
1978年 | 15篇 |
1977年 | 17篇 |
1976年 | 38篇 |
1975年 | 11篇 |
1974年 | 10篇 |
1973年 | 14篇 |
1970年 | 7篇 |
排序方式: 共有1886条查询结果,搜索用时 0 毫秒
1.
Luca Pietrobon Lorenzo Fallarino Andreas Berger Andrey Chuvilin Flix Casanova Luis E. Hueso 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(47):6295-6301
Graphene has been predicted to develop a magnetic moment by proximity effect when placed on a ferromagnetic film, a promise that could open exciting possibilities in the fields of spintronics and magnetic data recording. In this work, the interplay between the magnetoresistance of graphene and the magnetization of an underlying ferromagnetic insulating film is studied in detail. A clear correlation between both magnitudes is observed but through a careful modeling of the magnetization and the weak localization measurements, that such correspondence can be explained by the effects of the magnetic stray fields arising from the ferromagnetic insulator is found. The results emphasize the complexity arising at the interface between magnetic and 2D materials. 相似文献
2.
3.
Behavior of Magnesium‐Alloys for Automotive Applications under Mechanical and Environmental Loading: Influence of Passivating Films and Mechanisms of Local Breakdown To assure an efficient design of components under cyclic loading, all available data concerning fatigue have to be observed. Therefore the influences of manufacturing on the material condition, the mechanical loads and environmental effects have to be analysed. Magnesium‐alloys are of special interest for lightweight applications because of their excellent strength‐density ratio. The corrosion resistance of magnesium‐alloys depends on the same factors that are critical to other metals. The alloys have a good stability to atmospheric exposure and a good resistance to attack by alkali, chromic and hydrofluoric acids. However, because of the electrochemical activity of magnesium, the relative importance of some factors is greatly amplified. The nature and composition of passive films formed on magnesium‐alloys depend on the prevailing conditions, viz. alloy‐composition, passivation potential, pH, electrolyte composition and temperature. Passive films may be damaged by local breakdown. Because of this, magnesium‐alloys suffer a degradation of their properties when exposed to an aqueous environment. The main topic of the present investigations is the verification of mechanisms of the local breakdown of the protecting film. At least two mechanisms are possible for this localization: mechanical breakdown by slip steps and electrochemical breakdown (for e.g. by the effects of chloride ions). Corrosion and passivation of different high purity alloys have been studied in different solutions (neutral, alkaline with specific anions and cations) using electrochemical techniques. The diecasted alloys were tested as produced and machined. The results clarified that depending on alloy/material and surface condition/corrosion environment different mechanisms for electrochemical breakdown of the protecting films are possible. Hence fatigue life under environmental loading is influenced by surface and testing conditions. 相似文献
4.
5.
Jun Chen Berger T. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(8):3385-3398
We consider a distributed source coding system in which several observations must be encoded separately and communicated to the decoder by using limited transmission rate. We introduce a robust distributed coding scheme which flexibly trades off between system robustness and compression efficiency. The optimality of this coding scheme is proved for various special cases. 相似文献
6.
A. Alt Dr.‐Ing. H. Mertens U. Arz L. Blessing C. Berger 《Materialwissenschaft und Werkstofftechnik》2007,38(5):402-409
High cycle fatigue of bolted connections Extensive tests regarding the influences on the fatigue of bolt‐nut‐connections of preloading with torsion, of preloading with yielding, of loading with superimposed bending and of the tested lot are processed. These influences are not yet known according to VDI 2230. New testing devices were designed for these tests, which allow a far less expensive operation and may easily be used for bolts of diameters up to M100 and testing frequencies up to 1000 Hz. The validity of fatigue resistance according to VDI 2230 is specified with respect to the test results. The determined influence of the tested lots is unexpectedly high. The manufacturing process of bolts should be improved to minimize this influence. 相似文献
7.
JA Burger A Ochs K Wirth DP Berger R Mertelsmann R Engelhardt M Roessle K Haag 《Canadian Metallurgical Quarterly》1997,8(2):200-202
BACKGROUND: The increase in portal vascular resistance is a significant complication of metastatic disease to the liver or locally advanced cancer, e.g., biliary cancer. PATIENTS AND METHODS: This paper describes the successful palliative treatment of two cancer patients with portal hypertension presenting with the symptoms of tense ascites, mesenteric congestion, and severe variceal bleeding. By creating a stenttract between a hepatic vein and a main branch of the portal vein and/or by placing an extendable stent into the portal vein, the transjugular intrahepatic portosystemic stent-shunt (TIPS) technique was used to decompress the portovascular system. RESULTS: The TIPS-technique offers a new, safe and effective palliation for malignant portal hypertension. In both patients, the symptoms of the portal hypertension disappeared after the procedure. This was accompanied by a significant improvement of the patients performance status allowing an early ambulation. CONCLUSION: Our findings demonstrate the feasibility and effectiveness of the TIPS procedure as a minimal invasive treatment for portal vein decompression in selected tumor patients. 相似文献
8.
F Liao G Alkhatib KW Peden G Sharma EA Berger JM Farber 《Canadian Metallurgical Quarterly》1997,185(11):2015-2023
The chemokine receptors CXCR4, CCR2B, CCR3, and CCR5 have recently been shown to serve along with CD4 as coreceptors for HIV-1. The tropisms of HIV-1 strains for subgroups of CD4(+) cells can be explained, at least partly, by the selective use of G protein-coupled receptors (GPCRs). We have identified a novel human gene, STRL33, located on chromosome 3 that encodes a GPCR with sequence similarity to chemokine receptors and to chemokine receptor-like orphan receptors. STRL33 is expressed in lymphoid tissues and activated T cells, and is induced in activated peripheral blood lymphocytes. When transfected into nonhuman NIH 3T3 cells expressing human CD4, the STRL33 cDNA rendered these cells competent to fuse with cells expressing HIV-1 envelope glycoproteins (Envs). Of greatest interest, STRL33, in contrast with CXCR4 or CCR5, was able to function as a cofactor for fusion mediated by Envs from both T cell line-tropic and macrophage-tropic HIV-1 strains. STRL33-transfected Jurkat cell lines also supported enhanced productive infection with HIV-1 compared with control Jurkat cells. Despite the sequence similarities between STRL33 and chemokine receptors, STRL33-transfected cell lines did not respond to any in a panel of chemokines. Based on the pattern of tissue expression of the STRL33 mRNA, and given the ability of STRL33 to function with Envs of differing tropisms, STRL33 may play a role in the establishment and/or progression of HIV-1 infection. 相似文献
9.
C Müller H Dienemann H Hoffmann H Berger M Storck A Jolk FW Schildberg 《Canadian Metallurgical Quarterly》1993,118(9):543-548
The treatment of tracheo-bronchial stenosis or tracheomalacia is mainly carried out by means of resection or tracheoplastic operative strategies. Since the introduction of metal-mesh stents, a definitive endoluminal therapy has to be considered under new aspects. Six patients with malignant stenosis or tracheomalacia due to compression were treated by implantation of Palmaz- or Wallstents. Immediately after the implantation, patients were relieved from dyspnoea, the forced inspiratory volume-1 (FIV1) was normalized. All implanted stents were well tolerated, even in the long-time follow-up (19 months). Bronchoscopic control showed overgrowth of the metal meshes by respiratory epithelium. The implantation of metal-mesh stents is an adequate alternative in the treatment of malignant stenosis and tracheomalacia. 相似文献
10.