全文获取类型
收费全文 | 1710168篇 |
免费 | 50183篇 |
国内免费 | 18785篇 |
专业分类
电工技术 | 51052篇 |
技术理论 | 56篇 |
综合类 | 25470篇 |
化学工业 | 318186篇 |
金属工艺 | 79323篇 |
机械仪表 | 59128篇 |
建筑科学 | 68881篇 |
矿业工程 | 22062篇 |
能源动力 | 58730篇 |
轻工业 | 116946篇 |
水利工程 | 19069篇 |
石油天然气 | 58465篇 |
武器工业 | 2719篇 |
无线电 | 225116篇 |
一般工业技术 | 300177篇 |
冶金工业 | 133888篇 |
原子能技术 | 36593篇 |
自动化技术 | 203275篇 |
出版年
2022年 | 18655篇 |
2021年 | 27297篇 |
2020年 | 20912篇 |
2019年 | 21786篇 |
2018年 | 22197篇 |
2017年 | 22642篇 |
2016年 | 28637篇 |
2015年 | 28628篇 |
2014年 | 43400篇 |
2013年 | 104710篇 |
2012年 | 51662篇 |
2011年 | 64115篇 |
2010年 | 58103篇 |
2009年 | 66138篇 |
2008年 | 57673篇 |
2007年 | 53661篇 |
2006年 | 59393篇 |
2005年 | 51483篇 |
2004年 | 48346篇 |
2003年 | 47386篇 |
2002年 | 45883篇 |
2001年 | 41617篇 |
2000年 | 41132篇 |
1999年 | 40983篇 |
1998年 | 37355篇 |
1997年 | 36319篇 |
1996年 | 35214篇 |
1995年 | 32128篇 |
1994年 | 30016篇 |
1993年 | 28567篇 |
1992年 | 27426篇 |
1991年 | 23865篇 |
1990年 | 23937篇 |
1989年 | 22759篇 |
1988年 | 21061篇 |
1987年 | 19170篇 |
1986年 | 18338篇 |
1985年 | 21489篇 |
1984年 | 22012篇 |
1983年 | 19944篇 |
1982年 | 19084篇 |
1981年 | 19092篇 |
1980年 | 17653篇 |
1979年 | 18221篇 |
1978年 | 17443篇 |
1977年 | 16541篇 |
1976年 | 16413篇 |
1975年 | 15761篇 |
1974年 | 15305篇 |
1973年 | 15362篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
Nilesh P. Vanikar Shantipal S. Ohol Saeede Goldar 《International Journal of Cast Metals Research》2018,31(4):249-259
Bottom pour ladles with stopper rod systems are commonly used in the metal casting industry. However, stopper rod bottom-pouring systems have not yet been developed for the lower thermal masses of alloys typically used in the investment casting industry. Large thermal masses used with bottom pour systems are typically limited for ladles larger than 700 kg and to certain alloys with higher fluidity and longer solidification time like cast iron, aluminum alloys etc. In this study, bottom pour ladle designs and low thermal mass refractory systems have been developed and evaluated in production investment foundry trials with 300 kg pouring ladle. The ladles system and pouring practices used will be described along with the results from the pouring trials for SS304 that represents typical alloys used in Investment casting industries. Optimization of the variables used in an experimentation using Genetic algorithm is also explained. 相似文献
993.
Golovin V. A. Pechnikov N. V. Shchelkov V. A. Tsivadze A. Yu. 《Protection of Metals and Physical Chemistry of Surfaces》2018,54(6):1221-1232
Protection of Metals and Physical Chemistry of Surfaces - The possibility is shown of creating a chart of local corrosion damage in the walls of heat-exchange tubes on the basis of the data of... 相似文献
994.
I. Shepa E. Mudra M. Vojtko P. Tatarko V. Girman O. Milkovic T. Sopcak V. Medvecka J. Dusza 《Ceramics International》2018,44(15):17925-17934
The aim of the present contribution is to study the influence of the post-spinning heat - treatment of single TiO2/PVP precursor fibers on the properties and morphology of the final titanium-based microfibers. The post-spinning treatment conditions were: calcination in air at 450–600?°C and pyrolysis in argon at 1000–1700?°C. Calcination resulted in a production of anatase-rich and pure rutile fibers. The use of an alternative sintering method, the low-temperature plasma treatment, led to the crystallization of the composite Magnéli phases/polymer fibers. As a result of the same one precursor, pyrolysis at 1000?°C, the Carbon/TiO2 composite fibers were obtained. Rising the treatment temperature in inert atmosphere led to the formation of the titanium carbide fibers. The formation process and all the obtained products were characterized by differential scanning calorimetry accompanied with thermogravimetric analysis (DSC/TGA), scanning and transmission electron microscopy (SEM, TEM), X-ray diffraction (XRD), and image analysis techniques. 相似文献
995.
Saba Mehrafzoon S.A. Hassanzadeh-Tabrizi Ashkan Bigham 《Ceramics International》2018,44(12):13951-13958
In this research, a bimodal nanoporous Baghdadite (NB) (Ca3ZrSi2O9) was prepared by a modified sol-gel method using P123 as a surfactant. The effects of P123's contents on the structural and textural properties as well as the drug delivery behavior of NB were assessed in vitro. The usage of P123 offered a new route for the synthesis of NB. The synthesized NB samples with different amounts of P123 were studied through X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), N2 adsorption-desorption, field emission scanning electron microscopy (FESEM) equipped with energy-dispersive X-ray analysis spectroscopy (EDAX) and transmission electron microscopy (TEM). The results showed that a single-phase Baghdadite was obtained by this new method at the calcination temperature of 800?°C. It was found that an increase in P123's content up to 0.025?mol changed the morphology of NB samples from mountain-like to needle-like. The potential application of NB samples as drug delivery agents was assessed by estimating their release properties up to 240?h. This research revealed that the synthesized Baghdadite could be used as a potential nanoporous carrier with controlled release capability in bone tissue regeneration. 相似文献
996.
L.C. Souza A.C.A. Silva N.O. Dantas P.C. Morais S.W. da Silva 《Ceramics International》2018,44(1):208-215
Successful fabrication of glass-based hybrid nanocomposites (GHNCs) incorporating Ag, core-shell CdSe/CdS and CdSxSe1?x nanoparticles (NPs) is herein reported. Both metallic (Ag) and semiconductor (CdSe/CdS) NPs were pre-synthesized, suspended in colloids and added into the sol-gel reaction medium which was used to fabricate the GHNCs. During fabrication of the nanocomposites a fraction (20–60%) of core-shell CdSe/CdS NPs was alloyed into CdSxSe1?x (0.20 < x < 0.35) NPs without changing morphology. Modulation of in situ alloying is possible via the relative content of organics added into the sol-gel protocol. Within colloids Ag (core-shell CdSe/CdS) NPs presented average diameter and polydispersity index of 49.5 nm (4.2 nm) and 0.41 (0.21), respectively. On the other hand, the Ag (core-shell CdSe/CdS) NPs’ average diameter and polydispersity index assessed from the GHNCs were respectively 51.5 nm (4.1 nm) and 0.43 (0.25), revealing negligible aggregation of the nanophases within the glass template. The new GHNCs herein introduced presented two independent excitonic transitions associated to homogenously dispersed semiconductor NPs, peaking around 420 nm (core-shell CdSe/CdS) and 650 nm (CdSxSe1?x) and matching the plasmonic resonance (Ag NPs) in the 400–500 nm range. We envisage that the new GHNCs represent very promising candidates for superior light manipulation while illuminated with multiple laser beams in quantum interference-based devices. 相似文献
998.
The application of deep learning in the field of object detection has
experienced much progress. However, due to the domain shift problem, applying an
off-the-shelf detector to another domain leads to a significant performance drop. A
large number of ground truth labels are required when using another domain to train
models, demanding a large amount of human and financial resources. In order to avoid
excessive resource requirements and performance drop caused by domain shift, this
paper proposes a new domain adaptive approach to cross-domain vehicle detection. Our
approach improves the cross-domain vehicle detection model from image space and
feature space. We employ objectives of the generative adversarial network and cycle
consistency loss for image style transfer in image space. For feature space, we align
feature distributions between the source domain and the target domain to improve the
detection accuracy. Experiments are carried out using the method with two different
datasets, proving that this technique effectively improves the accuracy of vehicle
detection in the target domain. 相似文献
999.
1000.
为解决21000工作面采空区及顶板涌水问题,根据工作面出水点的不同情况,采取了集水器导水、老塘设挡水堰截水、挖排水沟疏水等多项治水措施,经统计排水量达33~42m3/h,有效控制了水情,确保了工作面正常生产。 相似文献