全文获取类型
收费全文 | 227181篇 |
免费 | 20260篇 |
国内免费 | 9941篇 |
专业分类
电工技术 | 14189篇 |
技术理论 | 30篇 |
综合类 | 22853篇 |
化学工业 | 28437篇 |
金属工艺 | 9683篇 |
机械仪表 | 11547篇 |
建筑科学 | 31247篇 |
矿业工程 | 12829篇 |
能源动力 | 8358篇 |
轻工业 | 20993篇 |
水利工程 | 10720篇 |
石油天然气 | 12269篇 |
武器工业 | 3212篇 |
无线电 | 14228篇 |
一般工业技术 | 16664篇 |
冶金工业 | 11563篇 |
原子能技术 | 1688篇 |
自动化技术 | 26872篇 |
出版年
2024年 | 1081篇 |
2023年 | 3098篇 |
2022年 | 5886篇 |
2021年 | 7725篇 |
2020年 | 7489篇 |
2019年 | 5679篇 |
2018年 | 5367篇 |
2017年 | 6762篇 |
2016年 | 8038篇 |
2015年 | 8673篇 |
2014年 | 15436篇 |
2013年 | 13737篇 |
2012年 | 16335篇 |
2011年 | 18020篇 |
2010年 | 13204篇 |
2009年 | 13422篇 |
2008年 | 12297篇 |
2007年 | 14928篇 |
2006年 | 13535篇 |
2005年 | 11865篇 |
2004年 | 9860篇 |
2003年 | 8529篇 |
2002年 | 6983篇 |
2001年 | 5714篇 |
2000年 | 4891篇 |
1999年 | 3830篇 |
1998年 | 2724篇 |
1997年 | 2400篇 |
1996年 | 1963篇 |
1995年 | 1616篇 |
1994年 | 1374篇 |
1993年 | 1009篇 |
1992年 | 806篇 |
1991年 | 560篇 |
1990年 | 489篇 |
1989年 | 449篇 |
1988年 | 248篇 |
1987年 | 203篇 |
1986年 | 179篇 |
1985年 | 201篇 |
1984年 | 147篇 |
1983年 | 121篇 |
1982年 | 67篇 |
1981年 | 78篇 |
1980年 | 90篇 |
1979年 | 40篇 |
1978年 | 22篇 |
1977年 | 23篇 |
1975年 | 20篇 |
1959年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
《Food Control》2015
The aim of the study was to investigate annual and regional differences in the level of aflatoxin B1 (AFB1) in grains and dairy cattle feed. Maize (n = 972), wheat (n = 201), barley (n = 147), oat (n = 136), grain mixtures (n = 168), and dairy cattle feed (n = 325) were sampled from 2009 to 2013 on different farms and in different farm factories situated in four Croatian regions. The samples were analysed for AFB1 using the validated ELISA immunoassay. AFB1 was determined in 16.4% of all investigated samples, among which maize was proven to be the most contaminated, with 21.7% of the samples recovered during 2013 harbouring AFB1 in concentrations over the permissible ones. Levels higher than permitted were observed in 17.9% and 12.3% of grain mixtures and dairy cattle feed, respectively, whereas concentrations of AFB1 determined in other crops throughout the investigated period met the stipulated requirements. The results revealed the AFB1 occurrence to be significantly (p < 0.05) dependent on the cultivation region, with the highest levels generally found in maize harvested in 2013 and consequently in grain mixtures and cattle feed that can most likely be associated with climatic conditions as the most critical factor for mould formation, and thus also AFB1 production. 相似文献
3.
为检查工程质量,查找输水系统可能存在的问题并消除隐患,保障电站安全运行,福建仙游抽水蓄能电站在投产发电前,要对输水发电系统进行充水试验与放空排水试验,在试验过程中监测输水系统的应力、应变与渗漏水情况。本文以尾水系统为例,介绍了试验所应具备的工程条件、工作程序及技术要求、试验成果分析和存在问题处理等。试验表明,仙游抽水蓄能电站尾水系统设计合理,施工质量优良,结构可靠,可供同类工程参考与借鉴。 相似文献
4.
5.
文章通过对黑龙江省高效节水现状,存在问题的分析,结合黑龙江省高效节水发展的支撑能力,阐述黑龙江省节水增粮目标、任务及总体布局,为黑龙江省2012—2015年节水增粮实施提供依据。 相似文献
6.
7.
ABSTRACTIn this paper, we review some algebraic control system. Precisely, linear and bilinear systems on Euclidean spaces and invariant and linear systems on Lie groups. The fourth classes of systems have a common issue: to any class, there exists an associated subgroup. From this object, we survey the controllability property. Especially, from those coming from our contribution to the theory. 相似文献
8.
The Vehicle Routing Problem with Simultaneous Pickup and Delivery (VRPSPD) is an extension to the classical Vehicle Routing Problem (VRP), where customers may both receive and send goods simultaneously. The Vehicle Routing Problem with Mixed Pickup and Delivery (VRPMPD) differs from the VRPSPD in that the customers may have either pickup or delivery demand. However, the solution approaches proposed for the VRPSPD can be directly applied to the VRPMPD. In this study, an adaptive local search solution approach is developed for both the VRPSPD and the VRPMPD, which hybridizes a Simulated Annealing inspired algorithm with Variable Neighborhood Descent. The algorithm uses an adaptive threshold function that makes the algorithm self-tuning. The proposed approach is tested on well-known VRPSPD and VRPMPD benchmark instances derived from the literature. The computational results indicate that the proposed algorithm is effective in solving the problems in reasonable computation time. 相似文献
9.
Esteban Vera Pingitore María Silvina Juárez Tomás Birgitt Wiese 《Drug development and industrial pharmacy》2015,41(6):942-952
Context: The administration of pharmabiotics is a promising alternative to antimicrobial drugs for the treatment and/or prevention of female urogenital infections.Objective: To design pharmabiotic formulations including bioactive ingredients of microbial origin combined with non-microbial substances and then to evaluate the stability of the combinations during freeze-drying and storage.Materials and methods: Different formulations including Lactobacillus gasseri CRL 1263, Lactobacillus salivarius CRL 1328, salivaricin CRL 1328 (a bacteriocin) and non-microbial compounds (lactose, inulin and ascorbic acid) were assayed, and the ingredients were freeze-dried together or separately. The formulations were stored in gelatin capsules at 4?°C for 360?d.Results: The viability of lactobacilli was affected to different extents depending on the strains and on the formulations assayed. L. salivarius and ascorbic acid were successfully combined only after the freeze-drying process. Salivaricin activity was not detected in formulations containing L. gasseri. However, when combined with ascorbic acid, lactose, inulin or L. salivarius, the bacteriocin maintained its activity for 360?d. The selected microorganisms proved to be compatible for their inclusion in multi-strain formulations together with lactose, inulin and ascorbic acid. Salivaricin could be included only in a L. salivarius CRL 1328 single-strain formulation together with non-microbial substances.Conclusions: This study provides new insights into the design of urogenital pharmabiotics combining beneficial lactobacilli, salivaricin CRL 1328 and compounds with different functionalities. 相似文献
10.
《Intermetallics》2015
An equiatomic CoCrFeNiMn high-entropy alloy was synthesized by mechanical alloying (MA) and spark plasma sintering (SPS). During MA, a solid solution with refined microstructure of 10 nm which consists of a FCC phase and a BCC phase was formed. After SPS consolidation, only one FCC phase can be detected in the HEA bulks. The as-sintered bulks exhibit high compressive strength of 1987 MPa. An interesting magnetic transition associated with the structure coarsening and phase transformation was observed during SPS process. 相似文献