全文获取类型
收费全文 | 106036篇 |
免费 | 2935篇 |
国内免费 | 1405篇 |
专业分类
电工技术 | 2073篇 |
技术理论 | 2篇 |
综合类 | 3789篇 |
化学工业 | 15196篇 |
金属工艺 | 6084篇 |
机械仪表 | 4484篇 |
建筑科学 | 4167篇 |
矿业工程 | 1368篇 |
能源动力 | 1698篇 |
轻工业 | 4795篇 |
水利工程 | 1641篇 |
石油天然气 | 1913篇 |
武器工业 | 153篇 |
无线电 | 11562篇 |
一般工业技术 | 19020篇 |
冶金工业 | 3740篇 |
原子能技术 | 494篇 |
自动化技术 | 28197篇 |
出版年
2024年 | 95篇 |
2023年 | 421篇 |
2022年 | 673篇 |
2021年 | 961篇 |
2020年 | 776篇 |
2019年 | 649篇 |
2018年 | 15021篇 |
2017年 | 14049篇 |
2016年 | 10544篇 |
2015年 | 1468篇 |
2014年 | 1394篇 |
2013年 | 1476篇 |
2012年 | 4639篇 |
2011年 | 10909篇 |
2010年 | 9614篇 |
2009年 | 6788篇 |
2008年 | 7981篇 |
2007年 | 8939篇 |
2006年 | 1388篇 |
2005年 | 2373篇 |
2004年 | 1843篇 |
2003年 | 1801篇 |
2002年 | 1098篇 |
2001年 | 621篇 |
2000年 | 672篇 |
1999年 | 690篇 |
1998年 | 547篇 |
1997年 | 463篇 |
1996年 | 436篇 |
1995年 | 359篇 |
1994年 | 279篇 |
1993年 | 167篇 |
1992年 | 153篇 |
1991年 | 144篇 |
1990年 | 96篇 |
1989年 | 72篇 |
1988年 | 69篇 |
1987年 | 32篇 |
1986年 | 33篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 42篇 |
1965年 | 44篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
91.
湖南省地方电力是水利产业的重要支柱,对促进农村经济发展等多方面发挥了重要的作用,但在经营中还存在着一系列的困难,文章详细的介绍了地方电网在经营企业中存在的主要问题和解决问题的关键环节。 相似文献
92.
93.
Jon T. Carter Paul E. Krajewski Ravi Verma 《JOM Journal of the Minerals, Metals and Materials Society》2008,60(11):77-81
The hot blow forming of magnesium sheet offers significant opportunity for forming complex, lightweight parts for automotive
applications. This paper characterizes the elevated-temperature formability of AZ31 magnesium sheet materials and the effect
of processing conditions on the performance of these materials. In addition, magnesium sheet application development at General
Motors Corporation is reviewed. 相似文献
94.
Toshihiko Hoshide Junpei Fujita 《Journal of Materials Engineering and Performance》2008,17(5):627-632
Strength of ground ceramics may be affected by residual stress as well as surface flaws induced by grinding. Strength prediction
for ground ceramics is convenient for mechanical design of ceramic components. In this article, a numerical procedure based
on fracture mechanics was proposed to estimate strength distribution of ground ceramics by considering grinding-induced residual
stress. Bending strength and residual stress of ground ceramics were measured for three grinding-conditions. By comparison
of simulated results with experimental ones, it was revealed that strength characteristics in experiments were well simulated
by using the proposed procedure. 相似文献
95.
本文提出了一种新的多变量解耦极点配置自校正前馈控制器,它具有使伺服跟踪性能和
随机调节性能两者均优的组合自校正特性.仿真例子说明了其有效性. 相似文献
96.
Zirconium(IV) tungstoiodophosphate has been synthesized under a variety of conditions. The most chemically and thermally stable
sample is prepared by adding a mixture of aqueous solutions of 0·5 mol L−1 sodium tungstate, potassium iodate and 1 mol L−1 orthophosphoric acid to aqueous solution of 0·1 mol L−1 zirconium(IV) oxychloride. Its ion exchange capacity for Na+ and K+ was found to be 2·20 and 2·35 meq g−1 dry exchanger, respectively. The material has been characterized on the basis of chemical composition, pH titration, Fourier
transform infrared spectroscopy (FTIR) and thermogravimetric analysis. The effect on the exchange capacity of drying the exchanger
at different temperatures has been studied. The analytical importance of the material has been established by quantitative
separation of Pb2+ from other metal ions. 相似文献
97.
Jonathan P. Belnoue Giang D. Nguyen Alexander M. Korsunsky 《International Journal of Fracture》2007,144(1):53-60
This paper presents a new 1-D non-local damage-plasticity deformation model for ductile materials. It uses the thermodynamic
framework described in Houlsby and Puzrin (2000) and holds, nevertheless, some similarities with Lemaitre’s (1971) approach.
A 1D finite element (FE) model of a bar fixed at one end and loaded in tension at the other end is introduced. This simple
model demonstrates how the approach can be implemented within the finite element framework, and that it is capable of capturing
both the pre-peak hardening and post-peak softening (generally responsible for models instability) due to damage-induced stiffness
and strength reduction characteristic of ductile materials. It is also shown that the approach has further advantages of achieving
some degree of mesh independence, and of being able to capture deformation size effects. Finally, it is illustrated how the
model permits the calculation of essential work of rupture (EWR), i.e. the specific energy per unit cross-sectional area that
is needed to cause tensile failure of a specimen. 相似文献
98.
Yewang Su Baohua Ji Yonggang Huang Kehchih Hwang 《Journal of Materials Science》2007,42(21):8885-8893
Wet adhesion is widely adopted in biological adhesion systems in nature. Wet adhesion is studied in this paper with the focus
on the effect of different contact shapes (flat, concave, convex, and ring-like) on the adhesion force. The evolution of the
liquid bridge between a fiber tip and substrate during the detaching process shows two transition points. The first transition
from the radius-controlled to the contact-angle controlled process is critical to influence the strength and robustness of
adhesion. We show that a concave shape is more effective than a flat one, while a convex shape has no advantage. A ring-like
contact shape has advantages in a hydrophobic environment and on a rough surface. 相似文献
99.
Jinting Jiu Seiji Isoda Motonari Adachi Hao Wang 《Journal of Materials Science: Materials in Electronics》2007,18(6):593-597
Nanocrystalline TiO2 with 3–10 nm in diameter was prepared with a surfactant-template method. Dye-sensitized solar cells were assembled using
the prepared nanocrystalline TiO2 with large surface area and high crystallinity, which achieved significant higher Jsc when compared to cells fabricated with
bigger particles of 25 nm in diameter. In the cells with nanocrystalline TiO2, the sintering temperature drastically affected the conversion performance of the cells. 相似文献
100.
Irine Banu Lucy 《Journal of Materials Science》2007,42(14):5875-5879
Capacitance and dielectric loss measurements were carried out using an Al/Cu–GeO2/Al sandwich structure for 0 to 10 vol% Cu films, 120–400 nm thick, deposited at 0.4–1.5 nm/s in the frequency and temperature
range 1–106 Hz and 90–573 K, respectively. The variation of capacitance and dielectric loss with frequency and temperature follows the
Goswami and Goswami model. Capacitance decreases slowly with increasing thickness and also varies with the change in deposition
rate of the cermet film. 相似文献