全文获取类型
收费全文 | 193949篇 |
免费 | 3515篇 |
国内免费 | 716篇 |
专业分类
电工技术 | 3612篇 |
综合类 | 156篇 |
化学工业 | 31970篇 |
金属工艺 | 8302篇 |
机械仪表 | 5540篇 |
建筑科学 | 5262篇 |
矿业工程 | 999篇 |
能源动力 | 4969篇 |
轻工业 | 18807篇 |
水利工程 | 1836篇 |
石油天然气 | 3153篇 |
武器工业 | 2篇 |
无线电 | 20919篇 |
一般工业技术 | 37900篇 |
冶金工业 | 33537篇 |
原子能技术 | 4423篇 |
自动化技术 | 16793篇 |
出版年
2021年 | 1750篇 |
2019年 | 1578篇 |
2018年 | 2730篇 |
2017年 | 2743篇 |
2016年 | 2908篇 |
2015年 | 2171篇 |
2014年 | 3463篇 |
2013年 | 9242篇 |
2012年 | 5422篇 |
2011年 | 7412篇 |
2010年 | 5953篇 |
2009年 | 6689篇 |
2008年 | 6801篇 |
2007年 | 6726篇 |
2006年 | 5663篇 |
2005年 | 5174篇 |
2004年 | 4877篇 |
2003年 | 4554篇 |
2002年 | 4531篇 |
2001年 | 4464篇 |
2000年 | 4197篇 |
1999年 | 4270篇 |
1998年 | 10546篇 |
1997年 | 7570篇 |
1996年 | 5807篇 |
1995年 | 4436篇 |
1994年 | 3742篇 |
1993年 | 3673篇 |
1992年 | 2705篇 |
1991年 | 2629篇 |
1990年 | 2492篇 |
1989年 | 2504篇 |
1988年 | 2436篇 |
1987年 | 2190篇 |
1986年 | 2114篇 |
1985年 | 2500篇 |
1984年 | 2325篇 |
1983年 | 2106篇 |
1982年 | 1971篇 |
1981年 | 2067篇 |
1980年 | 1885篇 |
1979年 | 1888篇 |
1978年 | 1851篇 |
1977年 | 2167篇 |
1976年 | 2750篇 |
1975年 | 1632篇 |
1974年 | 1604篇 |
1973年 | 1664篇 |
1972年 | 1379篇 |
1971年 | 1290篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Catalysis Letters - In this work we studied the reactivity of the Trifluoroacetic acid hydroxylamine system in the one step salt free synthesis of amides from ketones. A particular regards was paid... 相似文献
62.
63.
Maria A. Ospina Monica Pizarro Thierry Tran Julien Ricci John Belalcazar Jorge L. Luna Luis F. Londoño Sandra Salazar Hernan Ceballos Dominique Dufour Luis A. Becerra Lopez-Lavalle 《International Journal of Food Science & Technology》2021,56(3):1343-1353
The objective of this study was to characterise the nutritional potential of leaves and identify a diversity centre with low cyanide and high nutrient content among 178 Latin American cassava genotypes. This field-based collection represents the seven diversity centres, held at The International Center for Tropical Agriculture (CIAT Palmira, Colombia) by the Cassava Program. The cyanide, all-trans-β-carotene and lutein concentrations in cassava leaves ranged from 346 to 7484 ppm dry basis (db), from 174–547 μg g−1 db and 15–181 μg g−1 db, respectively. Cassava leaves also showed significant levels of essential amino acids leucine, lysine, phenylalanine, valine and threonine, and average total protein content of 26.24 g 100 g−1 db. Among seven diversity centres, South American rainforest group showed low cyanide and high carotene content in leaves. In addition, VEN77 and PAN51 genotypes stood out for having low cyanide in leaves and roots and high carotene in leaves. This genetic diversity can be used to select high potential progenitors for breeding purposes. 相似文献
64.
Kooij Julian F. P. Flohr Fabian Pool Ewoud A. I. Gavrila Dariu M. 《International Journal of Computer Vision》2019,127(3):239-262
International Journal of Computer Vision - Anticipating future situations from streaming sensor data is a key perception challenge for mobile robotics and automated vehicles. We address the problem... 相似文献
65.
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
66.
67.
A. A. Babenko V. I. Zhuchkov L. A. Smirnov A. V. Sychev A. A. Akberdin A. S. Kim M. F. Vitushchenko A. A. Dobromilov 《Steel in Translation》2015,45(11):883-886
A technology for slag formation in the ladle–furnace unit is considered; the slag is based on the CaO–SiO2–MgO–Al2O3–B2O3 system. This technology permits both microalloying of the steel with boron (reduced from the oxide phase) and desulfurization of the steel. The resulting boron content in the steel is 0.001–0.008%; the sulfur content in low-alloy steel and pipe steel is low (0.004–0.010%); and the consumption of manganese ferroalloys is reduced to 0.5 kg/t for 08кп steel and 1.4 kg/t for 09Г2C steel. In addition, the proposed technology increases the strength of the rolled steel, without loss in its plasticity; and reduces the environmental impact thanks to the replacement of fluorspar by colemanite. 相似文献
68.
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
69.
70.