全文获取类型
收费全文 | 317497篇 |
免费 | 5004篇 |
国内免费 | 1698篇 |
专业分类
电工技术 | 5601篇 |
综合类 | 241篇 |
化学工业 | 46803篇 |
金属工艺 | 11373篇 |
机械仪表 | 9659篇 |
建筑科学 | 8190篇 |
矿业工程 | 1015篇 |
能源动力 | 8818篇 |
轻工业 | 33769篇 |
水利工程 | 2895篇 |
石油天然气 | 4100篇 |
武器工业 | 46篇 |
无线电 | 39651篇 |
一般工业技术 | 60829篇 |
冶金工业 | 57512篇 |
原子能技术 | 5866篇 |
自动化技术 | 27831篇 |
出版年
2021年 | 2619篇 |
2020年 | 1984篇 |
2019年 | 2367篇 |
2018年 | 4012篇 |
2017年 | 4064篇 |
2016年 | 4497篇 |
2015年 | 3026篇 |
2014年 | 5053篇 |
2013年 | 15081篇 |
2012年 | 8776篇 |
2011年 | 12118篇 |
2010年 | 9527篇 |
2009年 | 10698篇 |
2008年 | 11160篇 |
2007年 | 11142篇 |
2006年 | 10158篇 |
2005年 | 9149篇 |
2004年 | 8782篇 |
2003年 | 8628篇 |
2002年 | 8087篇 |
2001年 | 8485篇 |
2000年 | 7800篇 |
1999年 | 8174篇 |
1998年 | 19496篇 |
1997年 | 13586篇 |
1996年 | 10251篇 |
1995年 | 7845篇 |
1994年 | 6855篇 |
1993年 | 6748篇 |
1992年 | 4881篇 |
1991年 | 4726篇 |
1990年 | 4528篇 |
1989年 | 4326篇 |
1988年 | 4143篇 |
1987年 | 3399篇 |
1986年 | 3316篇 |
1985年 | 4007篇 |
1984年 | 3522篇 |
1983年 | 3274篇 |
1982年 | 2966篇 |
1981年 | 3006篇 |
1980年 | 2811篇 |
1979年 | 2656篇 |
1978年 | 2448篇 |
1977年 | 2888篇 |
1976年 | 3602篇 |
1975年 | 2126篇 |
1974年 | 1997篇 |
1973年 | 2065篇 |
1972年 | 1592篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
91.
92.
Spiridonova E. A. Rotko V. O. Samonin V. V. Podvyaznikov M. L. 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(1):45-51
Protection of Metals and Physical Chemistry of Surfaces - In this work, a universal sorbent has been obtained that works according to the mechanisms of chemisorption and adsorption by impregnating... 相似文献
93.
ABSTRACTGiven that online platforms disrupt established industries and challenge existing institutions, they can only be successful if their innovation becomes both legal and legitimate. This requires ‘institutional work’ that changes perceptions and regulations within society. Rather than only focussing on the online platform as the sole agent engaging in institutional work, our study analyses institutional work as a collective process. We investigate the case of home-sharing platform Airbnb and the process of institutional change its introduction prompted regarding short-term rental in Amsterdam, London and New York. We find, contrary to the popular view of online platforms as disruptive entrepreneurs, that the platform mainly focusses on creating new institutions rather than disrupting existing ones, and that users and non-users undertake most of the institutional work activities. We also show that different types of actors carry out different types of institutional work suggesting that the process of institutional work is highly distributed. 相似文献
94.
D.R. Santos‐Peñate C.M. Campos‐Rodríguez J.A. Moreno‐Pérez 《International Transactions in Operational Research》2019,26(1):340-363
The ‐centroid problem or leader–follower problem is generalized considering different customer choice rules where a customer may use facilities belonging to different firms, if the difference in travel distance (or time) is small enough. Assuming essential goods, some particular customer choice rules are analyzed. Linear programming formulations for the generalized ‐medianoid and ‐centroid problems are presented and an exact solution approach is applied. Some computational examples are included. 相似文献
95.
High Temperature - Experimental findings suggest that a strongly ionized, arc He plasma of atmospheric pressure does not exist in the state of the local thermodynamic equilibrium (LTE) expected for... 相似文献
96.
Byakova O. V. Stepanov G. V. Vlasov A. O. Danylyuk V. E. Semenov N. V. Berezovs’kyi O. M. Gnyloskurenko S. V. 《Strength of Materials》2019,51(5):726-734
Strength of Materials - The paper addresses the investigation of high-strain rate compressive behavior of Al foams subjected to impact at the intermediate striking velocity ranged from 40 to... 相似文献
97.
Bram H. Frohock Jessica M. Gilbertie Dr. Jennifer C. Daiker Dr. Lauren V. Schnabel Dr. Joshua G. Pierce 《Chembiochem : a European journal of chemical biology》2020,21(7):933-937
The failure of frontline antibiotics in the clinic is one of the most serious threats to human health and requires a multitude of novel therapeutics and innovative approaches to treatment so as to curtail the growing crisis. In addition to traditional resistance mechanisms resulting in the lack of efficacy of many antibiotics, most chronic and recurring infections are further made tolerant to antibiotic action by the presence of biofilms. Herein, we report an expanded set of 5-benzylidene-4-oxazolidinones that are able to inhibit the formation of Staphylococcus aureus biofilms, disperse preformed biofilms, and, in combination with common antibiotics, are able to significantly reduce the bacterial load in a robust collagen-matrix model of biofilm infection. 相似文献
98.
ABSTRACT Design and implementation of an effective dissemination programme for decentralised renewable energy system necessitate an accurate estimate of its utilisation potential. Hence, in this study, an attempt has been made to develop frameworks to estimate the utilisation potential of decentralised renewable energy systems in the state of Uttarakhand in India. Estimations imply large resource, technical and economic potentials of the domestic solar water heater, solar home system, solar lantern, family size biogas plant and improved biomass cookstove in Uttarakhand. With higher impact on the purchasing power of households, prevailing soft loan scheme has been found to be more appropriate than a capital subsidy for promoting the usage of decentralised renewable energy systems. 相似文献
99.
100.
E. G. Kulapina N. M. Makarova O. I. Kulapina I. A. Utc V. V. Baraguzina 《Petroleum Chemistry》2015,55(10):892-900
Potentiometric sensors with plasticized poly(vinyl chloride) membranes based on β-lactam–tetraalkylammonium ion associates sensitive to penicillin antibiotics are proposed. The physicochemical characteristics (solubility product constants and dissociation constants) of active membrane components and the electrode, transport, and selective properties of the membranes of liquidand solid-contact sensors have been studied. The quantitative characteristics of membrane transport (penetrability, ion flux, and transport rate) have been evaluated. The main charge carriers in the membranes and at the membrane/solution interface have been determined from the membrane transport characteristics. The potentiometric sensors are shown to be applicable to the determination of penicillin antibiotics in biological fluids (blood serum and oral fluid) from patients with urinary tract infection. 相似文献