全文获取类型
收费全文 | 645112篇 |
免费 | 8691篇 |
国内免费 | 1874篇 |
专业分类
电工技术 | 11353篇 |
综合类 | 2841篇 |
化学工业 | 93824篇 |
金属工艺 | 28416篇 |
机械仪表 | 22163篇 |
建筑科学 | 15668篇 |
矿业工程 | 3329篇 |
能源动力 | 16001篇 |
轻工业 | 50763篇 |
水利工程 | 6992篇 |
石油天然气 | 10601篇 |
武器工业 | 38篇 |
无线电 | 72253篇 |
一般工业技术 | 127380篇 |
冶金工业 | 109604篇 |
原子能技术 | 11413篇 |
自动化技术 | 73038篇 |
出版年
2022年 | 3197篇 |
2021年 | 4941篇 |
2020年 | 3529篇 |
2019年 | 4619篇 |
2018年 | 25222篇 |
2017年 | 24578篇 |
2016年 | 19312篇 |
2015年 | 6451篇 |
2014年 | 9591篇 |
2013年 | 24510篇 |
2012年 | 18916篇 |
2011年 | 33463篇 |
2010年 | 27920篇 |
2009年 | 27167篇 |
2008年 | 28069篇 |
2007年 | 29981篇 |
2006年 | 15793篇 |
2005年 | 17831篇 |
2004年 | 15940篇 |
2003年 | 15547篇 |
2002年 | 13628篇 |
2001年 | 13009篇 |
2000年 | 12174篇 |
1999年 | 12719篇 |
1998年 | 32911篇 |
1997年 | 22979篇 |
1996年 | 17558篇 |
1995年 | 13086篇 |
1994年 | 11355篇 |
1993年 | 11033篇 |
1992年 | 7970篇 |
1991年 | 7483篇 |
1990年 | 7291篇 |
1989年 | 7049篇 |
1988年 | 6501篇 |
1987年 | 5800篇 |
1986年 | 5683篇 |
1985年 | 6298篇 |
1984年 | 5944篇 |
1983年 | 5208篇 |
1982年 | 4933篇 |
1981年 | 4998篇 |
1980年 | 4733篇 |
1979年 | 4629篇 |
1978年 | 4432篇 |
1977年 | 5353篇 |
1976年 | 6995篇 |
1975年 | 3820篇 |
1974年 | 3561篇 |
1973年 | 3676篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Dr. Yahu A. Liu Dr. Qihui Jin Qiang Ding Dr. Xueshi Hao Tingting Mo Shanshan Yan Dr. Yefen Zou Dr. Zhihong Huang Xiaoyue Zhang Wenqi Gao Dr. Tom Y.-H. Wu Chun Li Dr. Badry Bursalaya Dr. Michael Di Donato Dr. You-Qing Zhang Lisa Deaton Dr. Weijun Shen Dr. Brandon Taylor Anwesh Kamireddy Dr. George Harb Dr. Jing Li Dr. Yong Jia Dr. Andrew M. Schumacher Dr. Bryan Laffitte Dr. Richard Glynne Dr. Shifeng Pan Dr. Peter McNamara Dr. Valentina Molteni Dr. Jon Loren 《ChemMedChem》2020,15(16):1562-1570
Loss of β-cell mass and function can lead to insufficient insulin levels and ultimately to hyperglycemia and diabetes mellitus. The mainstream treatment approach involves regulation of insulin levels; however, approaches intended to increase β-cell mass are less developed. Promoting β-cell proliferation with low-molecular-weight inhibitors of dual-specificity tyrosine-regulated kinase 1A (DYRK1A) offers the potential to treat diabetes with oral therapies by restoring β-cell mass, insulin content and glycemic control. GNF4877, a potent dual inhibitor of DYRK1A and glycogen synthase kinase 3β (GSK3β) was previously reported to induce primary human β-cell proliferation in vitro and in vivo. Herein, we describe the lead optimization that lead to the identification of GNF4877 from an aminopyrazine hit identified in a phenotypic high-throughput screening campaign measuring β-cell proliferation. 相似文献
102.
A. M. Mirzabaev V. P. Kanonerov T. A. Makhkamov O. R. Sytdykov Sh. M. Mirzabekov 《Applied Solar Energy》2018,54(3):224-226
The data on the use of solar photovoltaic plants (PVPs) for providing a reliable and guaranteed power supply to telecommunication systems and cellular communication systems in the conditions prevalent in Uzbekistan are given. The research-based structures developed by OOO MIR SOLAR and the selection of PVP elements ensuring their reliable operation are described. The main influencing factors are discussed, and the use of effective combinations of different types of panels (from monocrystalline and polycrystalline silicon) and a specially developed controller are considered. 相似文献
103.
D. M. Mukhammadiev F. Kh. Ibragimov T. D. Mukhammadiev 《Journal of Machinery Manufacture and Reliability》2020,49(3):256-262
The dynamic characteristics of a saw gin as a subsystem with lumped and distributed parameters are considered in the paper. On the basis of investigation of the machine assembly, graphs are drawn that allow establishing the maximum values of the angle of relative rotation and the angle of rotation of the saw cylinder shaft under torsion. 相似文献
104.
C. G. Prosgolitis S. G. Lambrakos A. D. Zervaki 《Journal of Materials Engineering and Performance》2018,27(10):5102-5113
This work presents simulation of microstructure evolution in the nugget zone (NZ) of a AZ31-Mg-alloy friction stir weld. The process parameters (tool geometrical characteristics, rotational speed, travel speed, applied load) have been correlated with the resulting microstructural features in the NZ of the weld (grain size and population) with the aid of the MICRESS software, which provides the ability to simulate both nucleation and grain growth during dynamic recrystallization phenomena evolving in the NZ during the weld thermal cycle. The input parameters of the developed model include the tool geometry, the welding conditions as well as the recrystallization energy, the grain boundary mobility and specific material properties. NZ microstructure obtained by simulation shows good agreement with experimental measurements for both grain population and size. 相似文献
105.
106.
Carbon supported bimetallic Ru‐Co catalysts for H2 production through NaBH4 and NH3BH3 hydrolysis 下载免费PDF全文
This work investigates the effect of the addition of small amounts of Ru (0.5‐1 wt%) to carbon supported Co (10 wt%) catalysts towards both NaBH4 and NH3BH3 hydrolysis for H2 production. In the sodium borohydride hydrolysis, the activity of Ru‐Co/carbon catalysts was sensibly higher than the sum of the activities of corresponding monometallic samples, whereas for the ammonia borane hydrolysis, the positive effect of Ru‐Co systems with regard to catalytic activity was less evident. The performances of Ru‐Co bimetallic catalysts correlated with the occurrence of an interaction between Ru and Co species resulting in the formation of smaller ruthenium and cobalt oxide particles with a more homogeneous dispersion on the carbon support. It was proposed that Ru°, formed during the reduction step of the Ru‐Co catalysts, favors the H2 activation, thus enhancing the reduction degree of the cobalt precursor and the number of Co nucleation centers. A subsequent reduction of cobalt and ruthenium species also occurs in the hydride reaction medium, and therefore the state of the catalyst before the catalytic experiment determines the state of the active phase formed in situ. The different relative reactivity of the Ru and Co active species towards the two investigated reactions accounted for the different behavior towards NaBH4 and NH3BH3 hydrolysis. 相似文献
107.
Buryakov A. M. Khusyainov D. I. Mishina E. D. Khabibullin R. A. Yachmenev A. E. Ponomarev D. S. 《Technical Physics Letters》2018,44(12):1115-1119
Technical Physics Letters - The influence of excitation photons energy on the relaxation times of photoexcited carriers is studied. The involved relaxation mechanisms are evaluated and the... 相似文献
108.
109.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
110.
Sukharev S. V. Zabolotskii A. V. Kotrovskii P. V. Turchin M. Yu. 《Refractories and Industrial Ceramics》2020,60(6):539-542
Refractories and Industrial Ceramics - We study the problem of evaluation of the influence of design of the metal receiver of a large-capacity tundish of slab continuous-casting machine on the... 相似文献