全文获取类型
收费全文 | 4592篇 |
免费 | 15篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 13篇 |
化学工业 | 123篇 |
金属工艺 | 2篇 |
机械仪表 | 11篇 |
建筑科学 | 8篇 |
矿业工程 | 1篇 |
能源动力 | 17篇 |
轻工业 | 94篇 |
水利工程 | 1篇 |
无线电 | 20篇 |
一般工业技术 | 51篇 |
冶金工业 | 4217篇 |
原子能技术 | 5篇 |
自动化技术 | 45篇 |
出版年
2023年 | 3篇 |
2022年 | 19篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 29篇 |
2012年 | 17篇 |
2011年 | 25篇 |
2010年 | 16篇 |
2009年 | 18篇 |
2008年 | 23篇 |
2007年 | 20篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 140篇 |
1998年 | 1408篇 |
1997年 | 797篇 |
1996年 | 480篇 |
1995年 | 281篇 |
1994年 | 246篇 |
1993年 | 244篇 |
1992年 | 30篇 |
1991年 | 56篇 |
1990年 | 43篇 |
1989年 | 41篇 |
1988年 | 51篇 |
1987年 | 51篇 |
1986年 | 36篇 |
1985年 | 49篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 23篇 |
1980年 | 31篇 |
1978年 | 11篇 |
1977年 | 84篇 |
1976年 | 145篇 |
1975年 | 5篇 |
1963年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有4608条查询结果,搜索用时 0 毫秒
81.
82.
Difficulties of diagnosis of pleural neoplasms in biopsies are discussed. The short history of serous tumors as entity, their classification, methodological approaches to their morphological diagnosis are outlined. It is concluded that the problem of neoplastic pleural diseases verification can be solved by clinical and morphological correlations. Histochemistry, immunomorphology, and electron microscopy should be combined with conventional morphologic methods used in biopsy investigations. 相似文献
83.
The Wetox® process has been proven effective on a variety of industrial and municipal waste streams. Many of these streams contained chemicals whichAn advantage of the technology is that elements such as sulphur, chlorine and nitrogen are retained in solution, thus minimizing any potential air pollThe first commercial Wetox system has been installed at a chemical company in Ontario in the spring of 1982. This unit is being designed to treat about 相似文献
84.
Extreme flows, that is extreme points of the feasible set for network flow problems, play a fundamental role in most optimization
problems. The adiacency relation between extreme flows is investigated, and a theorem is stated, which, for any extreme flow
on a given network, defines a one-to-one correspondence between the set of its neighboring extreme flows and a set of cycles. 相似文献
85.
86.
87.
Antennas and Propagation for On-Body Communication Systems 总被引:3,自引:0,他引:3
Hall P.S. Yang Hao Nechayev Y.I. Alomalny A. Constantinou C.C. Parini C. Kamarudin M.R. Salim T.Z. Hee D.T.M. Dubrovka R. Owadally A.S. Wei Song Serra A. Nepa P. Gallo M. Bozzetti M. 《Antennas and Propagation Magazine, IEEE》2007,49(3):41-58
On-body communication channels are of increasing interest for a number of applications, such as medical-sensor networks, emergency-service workers, and personal communications. This paper describes investigations into channel characterization and antenna performance at 2.45 GHz. It is shown that significant channel fading occurs during normal activity, due primarily to the dynamic nature of the human body, but also due to multipath around the body and from scattering by the environment. This fading can be mitigated by the use of antenna diversity, and gains of up to 10 dB are obtained. Separation of the antenna's performance from the channel characteristics is difficult, but results show that for many channels, an antenna polarized normal to the body's surface gives the best path gain. Simulation and modeling present many challenges, particularly in terms of the problem's scale, and the need for accurate modeling of the body and its movement. 相似文献
88.
Daniel Raucoules Damien Raffard Jérémy Rohmer Annick Loschetter Marcello De Michele Yann Le Gallo 《International journal of remote sensing》2013,34(11):2800-2815
This article proposes to test the feasibility of long-term surface deformation monitoring based on synthetic aperture radar (SAR) interferometry on carbon dioxide (CO2) storage sites with land cover representative of potential European injection sites (agricultural or forests with minimum built-up land cover). Because no operational injection site is currently active in Europe, a SAR data set (based on EnviSAT–ASAR spaceborne data) is simulated by combining SAR scenes acquired over a potential future European injection site with deformation measurements from SAR analysis carried out on the In-Salah (Algeria) CO2 injection demonstrator site. The study shows that under such conditions, both persistent scatterer interferometry (PSI) and diffuse scatterer (DS) interferometry appear insufficient to provide a sufficiently dense measurement network to characterize surface deformation correctly. Alternative solutions, to be investigated in further studies, include the use of data archives with shorter acquisition time spans (e.g. Sentinel-1 data when available) or installation of corner reflectors. The cost of the latter mixed space/ground solution must be evaluated with respect to conventional ground-based measurement methods in the proposed context. 相似文献
89.
S Fong SJ Hamill M Proctor SM Freund GM Benian C Chothia M Bycroft J Clarke 《Canadian Metallurgical Quarterly》1996,264(3):624-639
The NMR solution structure of an immunoglobulin superfamily module of twitchin (Ig 18') has been determined and the kinetic and equilibrium folding behaviour characterised. Thirty molecular coordinates were calculated using a hybrid distance geometry-simulated annealing protocol based on 1207 distance and 48 dihedral restraints. The atomic rms distributions about the mean coordinate for the ensemble of structures is 0.55( +/- 0.09) A for backbone atoms and 1.10( +/- 0.08) A for all heavy atoms. The protein has a topology very similar to that of telokin and the titin Ig domains and thus it falls into the I set of the immunoglobulin superfamily. The close agreement between the predicted and observed structures of Ig 18' demonstrates clearly that the I set profile can be applied in the structure prediction of immunoglobulin-like domains of diverse modular proteins. Folding studies reveal that the protein has relatively low thermodynamic stability, deltaG(H2O)U-F = 4.0 kcal mol(-1) at physiological pH. Unfolding studies suggest that the protein has considerable kinetic stability, the half life of the unfolding is greater than 40 minutes in the absence of denaturant. 相似文献
90.
SD Gettings RA Lordo KL Hintze DM Bagley PL Casterton M Chudkowski RD Curren JL Demetrulias LC Dipasquale LK Earl PI Feder CL Galli SM Glaza VC Gordon J Janus PJ Kurtz KD Marenus J Moral WJ Pape KJ Renskers LA Rheins MT Roddy MG Rozen JP Tedeschi J Zyracki 《Canadian Metallurgical Quarterly》1996,34(1):79-117
The CTFA Evaluation of Alternatives Program is an evaluation of the relationship between data from the Draize primary eye irritation test and comparable data from a selection of promising in vitro eye irritation tests. In Phase III, data from the Draize test and 41 in vitro endpoints on 25 representative surfactant-based personal care formulations were compared. As in Phase I and Phase II, regression modelling of the relationship between maximum average Draize score (MAS) and in vitro endpoint was the primary approach adopted for evaluating in vitro assay performance. The degree of confidence in prediction of MAS for a given in vitro endpoint is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curve. Prediction intervals reflect not only the error attributed to the model but also the material-specific components of variation in both the Draize and the in vitro assays. Among the in vitro assays selected for regression modeling in Phase III, the relationship between MAS and in vitro score was relatively well defined. The prediction bounds on MAS were most narrow for materials at the lower or upper end of the effective irritation range (MAS = 0-45), where variability in MAS was smallest. This, the confidence with which the MAS of surfactant-based formulations is predicted is greatest when MAS approaches zero or when MAS approaches 45 (no comment is made on prediction of MAS > 45 since extrapolation beyond the range of observed data is not possible). No single in vitro endpoint was found to exhibit relative superiority with regard to prediction of MAS. Variability associated with Draize test outcome (e.g. in MAS values) must be considered in any future comparisons of in vivo and in vitro test results if the purpose is to predict in vivo response using in vitro data. 相似文献