全文获取类型
收费全文 | 153045篇 |
免费 | 14900篇 |
国内免费 | 9350篇 |
专业分类
电工技术 | 11271篇 |
技术理论 | 7篇 |
综合类 | 11845篇 |
化学工业 | 22397篇 |
金属工艺 | 9704篇 |
机械仪表 | 10660篇 |
建筑科学 | 12266篇 |
矿业工程 | 4985篇 |
能源动力 | 4745篇 |
轻工业 | 10868篇 |
水利工程 | 3714篇 |
石油天然气 | 7477篇 |
武器工业 | 1819篇 |
无线电 | 18028篇 |
一般工业技术 | 16570篇 |
冶金工业 | 6405篇 |
原子能技术 | 2302篇 |
自动化技术 | 22232篇 |
出版年
2024年 | 696篇 |
2023年 | 2239篇 |
2022年 | 4318篇 |
2021年 | 6174篇 |
2020年 | 4616篇 |
2019年 | 3924篇 |
2018年 | 4294篇 |
2017年 | 4874篇 |
2016年 | 4557篇 |
2015年 | 6502篇 |
2014年 | 8238篇 |
2013年 | 9550篇 |
2012年 | 11250篇 |
2011年 | 12211篇 |
2010年 | 11198篇 |
2009年 | 10729篇 |
2008年 | 10620篇 |
2007年 | 10179篇 |
2006年 | 9529篇 |
2005年 | 7707篇 |
2004年 | 5728篇 |
2003年 | 4811篇 |
2002年 | 4809篇 |
2001年 | 4131篇 |
2000年 | 3260篇 |
1999年 | 2634篇 |
1998年 | 1662篇 |
1997年 | 1370篇 |
1996年 | 1193篇 |
1995年 | 1016篇 |
1994年 | 751篇 |
1993年 | 606篇 |
1992年 | 442篇 |
1991年 | 333篇 |
1990年 | 257篇 |
1989年 | 200篇 |
1988年 | 167篇 |
1987年 | 102篇 |
1986年 | 112篇 |
1985年 | 47篇 |
1984年 | 44篇 |
1983年 | 42篇 |
1982年 | 31篇 |
1981年 | 26篇 |
1980年 | 20篇 |
1979年 | 18篇 |
1977年 | 15篇 |
1970年 | 6篇 |
1959年 | 17篇 |
1951年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
1 INTRODUCTIONTheorthorhombicalloysareofgreattech nolog icalinterestinhightemperatureapplicationssincetheyhaveagoodbalanceamongst 相似文献
52.
Qiu Jun Wang Yueting Wu Peng Jiang Shan Cui Kaibo Chen Guowei Liu Dongliang Cui Guangwen 《Journal of Porous Materials》2021,28(6):1675-1687
Journal of Porous Materials - The dynamics and thermodynamics of adsorption of hexadecyl ammonium with different numbers of carbon chains in montmorillonite (Mt) with different layer charge density... 相似文献
53.
54.
脲醛呋喃树脂中的含氮量,一般采用克氏定氮法,方法繁琐,费时较长,不利于快速分析的要求,本文利用气相色谱法对脲醛呋喃树脂中的氮含量进行分析测定,并建立了测定方法.方法简捷、快速、重现性好,加标回收率在100.8~109.0之间,准确度较高,可很好的满足工业生产中快速分析的要求. 相似文献
55.
Silicon - In this paper, an analytical model for negative capacitance double gate field effect transistor (NC-DG-FET) is proposed. This model includes interface traps and temperature effects, which... 相似文献
56.
Shuya Liang Miaomiao Wang Jun Wang Guanzhi Chen 《Chembiochem : a European journal of chemical biology》2021,22(22):3184-3189
To overcome high toxicity, low bioavailability and poor water solubility of chemotherapeutics, a variety of drug carriers have been designed. However, most carriers are severely limited by low drug loading capacity and adverse side effects. Here, a new type of metal-drug nanoparticles (MDNs) was designed and synthesized. The MDNs self-assembled with Fe(III) ions and drug molecules through coordination, resulting in nanoparticles with high drug loading. To assist systemic delivery and prolong circulation time, the obtained MDNs were camouflaged with red blood cell (RBCs) membranes (RBCs@Fe-DOX MDNs) to improve their stability and dispersity. The RBCs@Fe-DOX MDNs presented pH-responsive release functionalities, resulting in drug release accelerated in acidic tumor microenvironments. The outstanding in vitro and in vivo antitumor therapeutic outcome was realized by RBCs@Fe-DOX MDNs. This study provides an innovative design guideline for chemotherapy and demonstrates the great capacity of nanomaterials in anticancer treatments. 相似文献
57.
H. B. Wu Z. T. Fan N. Y. Huang X. P. Dong X. F. Tian 《Journal of Materials Engineering and Performance》2005,14(1):132-135
The magnesium (Mg) alloy low-pressure expendable pattern casting (EPC) process is a newly developed casting technique combining
the advantages of both EPC and low-pressure casting. In this article, metal filling and the effect of the flow quantity of
inert gas on the filling rate in the low-pressure EPC process are investigated. The results showed that the molten Mg alloy
filled the mold cavity with a convex front laminar flow and the metal-filling rate increased significantly with increasing
flow quantity when flow quantity was below a critical value. However, once the flow quantity exceeded a critical value, the
filling rate increased slightly. The influence of the flow quantity of inert gas on melt-filling rate reveals that the mold
fill is controlled by flow quantity for a lower filling rate, and, subsequently, controlled by the evaporation of polystyrene
and the evaporation products for higher metal velocity. Meanwhile, the experimental results showed that the melt-filling rate
significantly affected the flow profile, and the filling procedure for the Mg alloy in the low-pressure EPC process. A slower
melt-filling rate could lead to misrun defects, whereas a higher filling rate results in folds, blisters, and porosity. The
optimized filling rate with Mg alloy casting is 140 to 170 mm/s in low-pressure EPC. 相似文献
58.
59.
60.