首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3689篇
  免费   193篇
  国内免费   6篇
电工技术   58篇
综合类   3篇
化学工业   1018篇
金属工艺   79篇
机械仪表   88篇
建筑科学   144篇
矿业工程   6篇
能源动力   155篇
轻工业   295篇
水利工程   28篇
石油天然气   3篇
无线电   359篇
一般工业技术   732篇
冶金工业   223篇
原子能技术   34篇
自动化技术   663篇
  2023年   31篇
  2022年   82篇
  2021年   109篇
  2020年   56篇
  2019年   77篇
  2018年   88篇
  2017年   92篇
  2016年   122篇
  2015年   104篇
  2014年   151篇
  2013年   246篇
  2012年   224篇
  2011年   287篇
  2010年   188篇
  2009年   219篇
  2008年   229篇
  2007年   175篇
  2006年   182篇
  2005年   125篇
  2004年   113篇
  2003年   107篇
  2002年   126篇
  2001年   56篇
  2000年   56篇
  1999年   54篇
  1998年   74篇
  1997年   74篇
  1996年   49篇
  1995年   37篇
  1994年   42篇
  1993年   34篇
  1992年   21篇
  1991年   19篇
  1990年   21篇
  1989年   19篇
  1988年   11篇
  1987年   10篇
  1986年   14篇
  1985年   15篇
  1984年   17篇
  1983年   12篇
  1982年   14篇
  1981年   15篇
  1980年   8篇
  1979年   10篇
  1978年   10篇
  1977年   10篇
  1976年   10篇
  1975年   10篇
  1972年   6篇
排序方式: 共有3888条查询结果,搜索用时 10 毫秒
1.
Mosquito-borne Zika virus (ZIKV) became a real threat to human health due to the lack of vaccine and effective antiviral treatment. The virus has recently been responsible for a global outbreak leading to millions of infected cases. ZIKV complications were highlighted in adults with Guillain–Barré syndrome and in newborns with increasing numbers of congenital disorders ranging from mild developmental delays to fatal conditions. The ability of ZIKV to establish a long-term infection in diverse organs including the kidneys has been recently documented but the consequences of such a viral infection are still debated. Our study aimed to determine whether the efficiency of ZIKV growth in kidney cells relates to glucose concentration. Human kidney HK-2 cells were infected with different ZIKV strains in presence of normal and high glucose concentrations. Virological assays showed a decrease in viral replication without modifying entry steps (viral binding, internalization, fusion) under high glucose conditions. This decrease replication was associated with a lower virus progeny and increased cell viability when compared to ZIKV-infected HK-2 cells in normal glucose concentration. In conclusion, we showed for the first time that an elevated glucose level influences ZIKV replication level with an effect on kidney cell survival.  相似文献   
2.
3.
4.
5.
6.
BACKGROUND: In the framework of biological processes used for waste gas treatment, the impact of the inoculum size on the start‐up performance needs to be better evaluated. Moreover, only a few studies have investigated the behaviour of elimination capacity and biomass viability in a two‐phase partitioning bioreactor (TPPB) used for waste gas treatment. Lastly, the impact of ethanol as a co‐substrate remains misunderstood. RESULTS: Firstly, no benefit of inoculation with a high cellular density (>1.5 g L?1) was observed in terms of start‐up performance. Secondly, the TPPB was monitored for 38 days to characterise its behaviour under several operational conditions. The removal efficiency remained above 63% for an inlet concentration of 7 g isopropylbenzene (IPB) m?3 and at some time points reached 92% during an intermittent loading phase (10 h day?1), corresponding to a mean elimination capacity of 4 × 10?3 g L?1 min?1 (240 g m?3 h?1) for a mean IPB inlet load of 6.19 × 10?3 g L?1 min?1 (390 g m?3 h?1). Under continuous IPB loading, the performance of the TPPB declined, but the period of biomass acclimatisation to this operational condition was shorter than 5 days. The biomass grew to approximately 10 g L?1 but the cellular viability changed greatly during the experiment, suggesting an endorespiration phenomenon in the bioreactor. It was also shown that simultaneous degradation of IPB and ethanol occurred, suggesting that ethanol improves the biodegradation process without causing oxygen depletion. CONCLUSION: A water/silicone oil TPPB with ethanol as co‐substrate allowed the removal of a high inlet load of IPB during an experiment lasting 38 days. Copyright © 2008 Society of Chemical Industry  相似文献   
7.
8.
Critical Shear Stress of Bimodal Sediment in Sand-Gravel Rivers   总被引:1,自引:0,他引:1  
A new model for the critical shear stress and the transport of graded sediment is presented. The model is based on the size distribution of the bed surface and can be used to compute sediment transport rates in numerical simulations with an active layer model. This model makes a distinction between unimodal and bimodal sediments. It is assumed that all size fractions of unimodal sediments have the same critical shear stress while there is selective transport for the gravel fractions of bimodal sediments. A recently published laboratory transport data set is used to calibrate our model.  相似文献   
9.
This paper is dedicated to the determination of topological S parameters in the transmission line networks. We are especially interested in ideal junctions which consist of short circuit connections. For this type of junctions, it is impossible to deduce the S parameters from the usual impedance or admittance matrices which are not defined in this case. We suggest a method allowing a direct calculation of S. This procedure is described and then carried out for a two wire fork. At last, an experimental application is given for this model.  相似文献   
10.
Although lexical frequencies are familiar measures of stylistic and thematic analysis, only recently have some stylostatisticians been tempted to investigate the relationship between the frequency and topography of repeated lexical items. In the present paper the authors have turned to the study of the four focal types of discursive narratology, using Marguerite Duras'Moderato Cantabile. Their intent is to uncover aspects of narratological performance which further elucidate the communicative strategies in the story. Part 1 summarizes the problematic between frequency and topography. It describes how a topographical index can be computed for any repeated item and how a Global Topography Index (GTI) can summarize the major topographical characteristics of any text sequence. Part 2 presents a four-cell typology of narrational mode: a segmentation of the verbal chain into narrating and narrated speech acts, with each text sequence tagged according to its discursive function: overt sender intervention for story coherence or comment on the focal level of a narrating present; representation of discrete or unlocalized events on the focal level of a mimeticized past. In Part 3 the focal encodings are displayed in numerical and graphic form, first according to the eight surface chapter divisions and then according to twenty-six subsets of approximately equal length. The fluctuations of the topography indices are reviewed, with particular attention being paid to the manifestation of cluster effects. Although sender interventions predominate, the relativized behavior of each focal type contributes to a climactic unraveling of the intrigue in the final chapters. In conclusion, the authors stress the dichotomy between the calm surface of the chapters and the agitated tensions of the twenty-six subsets.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号