全文获取类型
收费全文 | 3509篇 |
免费 | 221篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 45篇 |
综合类 | 1篇 |
化学工业 | 966篇 |
金属工艺 | 122篇 |
机械仪表 | 91篇 |
建筑科学 | 80篇 |
矿业工程 | 15篇 |
能源动力 | 129篇 |
轻工业 | 541篇 |
水利工程 | 33篇 |
石油天然气 | 8篇 |
无线电 | 184篇 |
一般工业技术 | 808篇 |
冶金工业 | 73篇 |
原子能技术 | 46篇 |
自动化技术 | 590篇 |
出版年
2023年 | 40篇 |
2022年 | 49篇 |
2021年 | 115篇 |
2020年 | 96篇 |
2019年 | 116篇 |
2018年 | 171篇 |
2017年 | 162篇 |
2016年 | 157篇 |
2015年 | 156篇 |
2014年 | 195篇 |
2013年 | 403篇 |
2012年 | 205篇 |
2011年 | 254篇 |
2010年 | 251篇 |
2009年 | 185篇 |
2008年 | 120篇 |
2007年 | 94篇 |
2006年 | 54篇 |
2005年 | 25篇 |
2004年 | 39篇 |
2003年 | 42篇 |
2002年 | 38篇 |
2001年 | 32篇 |
2000年 | 42篇 |
1999年 | 25篇 |
1998年 | 31篇 |
1997年 | 30篇 |
1996年 | 19篇 |
1995年 | 25篇 |
1994年 | 23篇 |
1993年 | 26篇 |
1992年 | 24篇 |
1991年 | 20篇 |
1990年 | 17篇 |
1989年 | 16篇 |
1988年 | 13篇 |
1986年 | 11篇 |
1985年 | 20篇 |
1984年 | 29篇 |
1983年 | 21篇 |
1982年 | 30篇 |
1981年 | 45篇 |
1980年 | 35篇 |
1979年 | 25篇 |
1978年 | 25篇 |
1977年 | 24篇 |
1976年 | 39篇 |
1975年 | 24篇 |
1974年 | 16篇 |
1973年 | 23篇 |
排序方式: 共有3732条查询结果,搜索用时 15 毫秒
11.
Male lambs, crossbred Merino × Ille de France, were fed a diet supplemented with 31 mg monensin or 32 mg lasalocid per kg of feed dry matter from an initial body weight of 23·6–23·9 kg to the slaughter weight of approximately 40 kg.
Carcass traits and meat quality were evaluated after slaughter; the values obtained were compared with those of the control group fed the same diet without the ionophore supplement.
There were few significant differences among the individual groups in carcass value, sensoric and technological properties of meat and of its composition. However, the lasalocid-fed group seemed to be somewhat better in muscling and in the composition of meat. 相似文献
12.
Pori Maja Arčon Iztok Dasireddy Venkata D. B. C. Likozar Blaž Orel Zorica Crnjak Marinšek Marjan 《Catalysis Letters》2021,151(11):3114-3134
Catalysis Letters - Industrial Cu/ZnO/Al2O3 or novel rate catalysts, prepared with a photochemical deposition method, were studied under functional CH3OH synthesis conditions at the set temperature... 相似文献
13.
Summary The effect of tert-butyl chloride in the polymerizations of isobutylene carried out in the presence of SnCl4 in dichloromethane at temperatures-20°C and-78°C was investigated. Synthesized polyisobutylene samples showed a bimodal molecular
weight distribution (MWD) and it was found that the weight content of the lowermolecular weight (LMW) fraction increased with
increasing t-BuCl concentration in the polymerization mixture. The effect of ageing of the initiation mixture t-BuCl/SnCl4 in CH2Cl2 prepared in advance on MWD of the PIB samples was also studied. Ageing of the initiation system supports the formation of
the LMW fraction and this oily PIB is the only product of the polymerization at-20°C,
. 相似文献
14.
Martin Saska Tomáš Krajník Vojtěch Vonásek Zdeněk Kasl Vojtěch Spurný Libor Přeučil 《Journal of Intelligent and Robotic Systems》2014,73(1-4):603-622
A fault-tolerant method for stabilization and navigation of 3D heterogeneous formations is proposed in this paper. The presented Model Predictive Control (MPC) based approach enables to deploy compact formations of closely cooperating autonomous aerial and ground robots in surveillance scenarios without the necessity of a precise external localization. Instead, the proposed method relies on a top-view visual relative localization provided by the micro aerial vehicles flying above the ground robots and on a simple yet stable visual based navigation using images from an onboard monocular camera. The MPC based schema together with a fault detection and recovery mechanism provide a robust solution applicable in complex environments with static and dynamic obstacles. The core of the proposed leader-follower based formation driving method consists in a representation of the entire 3D formation as a convex hull projected along a desired path that has to be followed by the group. Such an approach provides non-collision solution and respects requirements of the direct visibility between the team members. The uninterrupted visibility is crucial for the employed top-view localization and therefore for the stabilization of the group. The proposed formation driving method and the fault recovery mechanisms are verified by simulations and hardware experiments presented in the paper. 相似文献
15.
An experimental study has been made of temperature profiles incident within a zeolite adsorbent particle in the course of adsorption of n-heptan. Using thermocouple wires 0.1 mm in diameter it has been possible to measure simultaneously the temperatures of the surface and in the centre. It was observed that temperature differences between center of the pellet and ambient stagnant gas may be more than 20°C. The results of this work indicate that the overheating of an adsorbent particle is a very rapid process which is followed by a slow cooling of the hot particle. Experimental data are compared with predictions calculated from the theoretical model. 相似文献
16.
Polymer Bulletin - Solutions of syndiotactic (s) poly (methyl methacrylate) (PMMA) and samples of solid s-PMMA prepared from these solutions were studied by NMR and infrared (IR) spectroscopy and... 相似文献
17.
Sintered negative electrodes for nickel-cadmium secondary cells were studied. Model electrodes prepared by means of three different impregnation methods were evaluated. It was demonstrated that the impregnation procedure may affect properties of active mass and the service life of electrodes in a significant way. 相似文献
18.
The enantioselective hydrogenation of ethyl pyruvate to (S)-ethyl lactate over cinchonine- and -isocinchonine-modified Pt/Al2O3 catalysts was studied as a function of modifier concentration and reaction temperature. The maximum enantioselectivities obtained under the applied mild conditions were 89% ee using cinchonine (0.014 mmoldm–3, 1 bar H2, 23°C, 6% AcOH in toluene), and 76% ee in the case of -isocinchonine (0.14 mmoldm–3, 1 bar H2, –10°C, 6% AcOH in toluene). Since -isocinchonine of rigid structure exists only in anti-open conformation these data provide additional experimental evidence to support the former suggestion concerning the dominating role of anti-open conformation in these cinchona-modified enantioselective hydrogenations. 相似文献
19.
The rotational mobility of stable nitroxide radicals in PS, PMMA, PVC, PP and PE has been studied over a wide temperature range by the e.s.r. method. At temperatures T lower than Tg, spin probes act as kinetically independent particles, the rotational frequency of which is deter mined mainly by the micropore dimensions of the polymer and depends indirectly on the mobility of segments or side groups. 相似文献
20.