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   6080篇
  免费   53篇
  国内免费   2篇
电工技术   21篇
综合类   6篇
化学工业   155篇
金属工艺   10篇
机械仪表   43篇
建筑科学   9篇
矿业工程   7篇
能源动力   20篇
轻工业   62篇
水利工程   4篇
石油天然气   5篇
无线电   112篇
一般工业技术   122篇
冶金工业   5472篇
原子能技术   4篇
自动化技术   83篇
  2023年   4篇
  2022年   14篇
  2021年   11篇
  2020年   13篇
  2019年   15篇
  2018年   19篇
  2017年   28篇
  2016年   31篇
  2015年   16篇
  2014年   29篇
  2013年   42篇
  2012年   35篇
  2011年   64篇
  2010年   41篇
  2009年   32篇
  2008年   42篇
  2007年   38篇
  2006年   26篇
  2005年   17篇
  2004年   17篇
  2003年   22篇
  2002年   15篇
  2001年   14篇
  2000年   14篇
  1999年   177篇
  1998年   1682篇
  1997年   932篇
  1996年   598篇
  1995年   341篇
  1994年   299篇
  1993年   315篇
  1992年   46篇
  1991年   61篇
  1990年   79篇
  1989年   67篇
  1988年   75篇
  1987年   73篇
  1986年   57篇
  1985年   65篇
  1984年   3篇
  1983年   13篇
  1982年   32篇
  1981年   30篇
  1980年   54篇
  1979年   6篇
  1978年   14篇
  1977年   158篇
  1976年   341篇
  1975年   5篇
  1955年   4篇
排序方式: 共有6135条查询结果,搜索用时 15 毫秒
41.
Flexible chemical sensors utilizing chemically sensitive nanomaterials are of great interest for wearable sensing applications. However, obtaining high performance flexible chemical sensors with high sensitivity, fast response, transparency, stability, and workability at ambient conditions is still challenging. Herein, a newly designed flexible and transparent chemical sensor of reduced graphene oxide (R‐GO) coupled with organic dye molecules (bromophenol blue) is introduced. This device has promising properties such as high mechanical flexibility (>5000 bending cycles with a bending radius of 0.95 cm) and optical transparency (>60% in the visible region). Furthermore, stacking the water‐trapping dye layer on R‐GO enables a higher response as well as workability in a large relative humidity range (up to 80%), and dual‐mode detection capabilities of colorimetric and electrical sensing for NH3 gas (5–40 ppm). These advantageous attributes of the flexible and transparent R‐GO sensor coupled with organic dye molecules provide great potential for real‐time monitoring of toxic gas/vapor in future practical chemical sensing at room conditions in wearable electronics.  相似文献   
42.
Titania precipitation on cotton has been achieved using a commercially available antimicrobial polymer, Reputex 20. The cotton swatches precipitated with titania retain antimicrobial activity, and we have also shown the ability to encapsulate diisopropylfluorophosphatase (DFPase), an enzyme capable of breaking down organofluorophosphates. Cotton swatches are easily prepared and precipitation occurs at room temperature in aqueous solutions at neutral pH. Both the antimicrobial properties of Reputex 20 and the hydrolytic activity of the DFPase enzyme are retained after titania precipitation, generating a cotton material exhibiting multifunctional properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43199.  相似文献   
43.
Proteins from Sulfolobus solfataricus (S. solfataricus), an extremophile, are active even at high temperatures. The single-stranded DNA (ssDNA) binding protein of S. solfataricus (SsoSSB) is overexpressed to protect ssDNA during DNA metabolism. Although SsoSSB has the potential to be applied in various areas, its structural and ssDNA binding properties at high temperatures have not been studied. We present the solution structure, backbone dynamics, and ssDNA binding properties of SsoSSB at 50 °C. The overall structure is consistent with the structures previously studied at room temperature. However, the loop between the first two β sheets, which is flexible and is expected to undergo conformational change upon ssDNA binding, shows a difference from the ssDNA bound structure. The ssDNA binding ability was maintained at high temperature, but different interactions were observed depending on the temperature. Backbone dynamics at high temperature showed that the rigidity of the structured region was well maintained. The investigation of an N-terminal deletion mutant revealed that it is important for maintaining thermostability, structure, and ssDNA binding ability. The structural and dynamic properties of SsoSSB observed at high temperature can provide information on the behavior of proteins in thermophiles at the molecular level and guide the development of new experimental techniques.  相似文献   
44.
For several decades, a porous surface has been recognized as an efficient medium to increase boiling performance in a nucleate boiling regime. Most feasible porous surfaces have been studied in millimeter and micron-sized domains. It has been believed that a higher wall superheat is required to commence incipient nucleate boiling under a submicron regime. In this study, we demonstrate that a significantly enhanced pool boiling heat transfer is observed in a submicron regime through three dimensionally interconnected hybrid pores: the Alumina sponge-like nano-porous structure (ASNPS). The structural uniqueness of the ASNPS leads to an enlarged surface area, increases the potential number of the active nucleation site density, and improves the vapor–liquid menisci through the reentrant pore. Simultaneously, by changing the surface wettability with a hydrophobic self-assembled monolayer (SAM) coating, the number of active nucleation site density is improved. Eventually, the combination of the ASNPS and hydrophobic SAM coating can achieve substantial heat transfer coefficient (HTC) enhancement in the nucleate boiling. Also, the thickness of the ASNPS is a critical issue to adequately augment the HTC in pool boiling. The thickness of the ASNPS is optimized by examining the boiling performance of the ASNPS fabricated in different amounts of anodizing times. A classical mechanistic model from literature was modified and compared with the experimentally obtained data. The modified mechanistic model – with the combination of forced-convection and thin liquid film evaporation – showed reasonable predictions.  相似文献   
45.
Wireless Personal Communications - In cloud-assisted data outsourcing systems, the privacy of sensitive data is a major concern. Thus, data are uploaded in encrypted form in many cloud applications...  相似文献   
46.
47.
Research has indicated that schizophrenia patients report similar amounts of experienced emotion in response to emotional material compared with nonpatients. However, less is known about how schizophrenia patients describe and make sense of their emotional life events. We adopted a narrative approach to investigate schizophrenia patients' renderings of their emotional life experiences. In Study 1, patients' (n = 42) positive and negative narratives were similarly personal, tellable, engaged, and appropriate. However, negative narratives were less grammatically clear than positive narratives, and positive narratives were more likely to involve other people than negative narratives. In Study 2, emotional (positive and negative) narratives were less tellable and detached, yet more linear and social compared with neutral narratives for both schizophrenia patients (n = 24) and healthy controls (n = 19). However, patients' narratives about emotional life events were less appropriate to context and less linear, and patients' narratives, whether emotional or not, were less tellable and more detached compared with controls' narratives. Although schizophrenia patients are capable of recounting life events that trigger different emotions, the telling of these life events is fraught with difficulty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
48.
We calculated the electrostatic force between a planar interface, such as a planar-supported lipid bilayer membrane, and the tip of a stylus on which another lipid bilayer or some other biomacromolecular system might be deposited. We considered styli with rounded tips as well as conical tips. To take into account the effect of dynamical hydrogen-bonded structures in the aqueous phase, we used a theory of nonlocal electrostatics. We used the Derjaguin approximation and identified the systems for which its use is valid. We pointed out where our approach differs from previous calculations and to what extent the latter are inadequate. We found that 1) the nonlocal interactions have significant effects over distances of 10-15 A from the polar zone and that, at the surface of this zone, the effect on the calculated force can be some orders of magnitude; 2) the lipid dipoles and charges are located a distance L from the hydrophobic layer in the aqueous medium and this can have consequences that may not be appreciated if it is ignored; 3) dipoles, located in the aqueous region, can give rise to forces even though the polar layer is unchanged, and if this is ignored the interpretation of force data can be erroneous if an attempt is made to rationalize an observed force with a knowledge of an uncharged surface; 4) the shape of the stylus tip can be very important, and a failure to take this into account can result in incorrect conclusions, a point made by other workers; and 5) when L is nonzero, the presence of charges and dipoles can yield a force that can be nonmonotonic as a function of ionic concentration.  相似文献   
49.
A highly vascular petroclival meningioma supplied by tentorial branches of the internal carotid artery was embolized by temporary balloon occlusion of the parent vessel distal to the tumor, followed by obliteration of the tumor vascularity with polyvinyl alcohol particles. Subsequently, in vivo proton spectroscopy showed necrosis of a large portion of the tumor and helped determine the timing of surgery. Both innovative techniques considerably facilitated the subsequent radical excision of the tumor with no neurological morbidity.  相似文献   
50.
Examined the role of counterfactual thinking in 2 emotions: shame and guilt. In 1 series of studies, Ss read about situations evocative of shame and guilt or described personal experiences of guilt or shame. They then generated counterfactual alternatives to "undo" the distressing outcomes. Consistent with predictions derived from J. P. Tangney (see record 1992-05447-001), Ss tended to undo shame situations by altering qualities of the self and to undo guilt situations by altering actions. In a 2nd series of studies, Ss imagined themselves in a situation that could evoke either guilt or shame. Ss were then led to mutate the self or behavior to undo the situation. Mutation manipulations amplified shame and guilt such that the former Ss anticipated feeling greater shame, whereas the latter anticipated feeling greater guilt. The role of counterfactual thinking in specific emotions and in differentiating shame and guilt-prone personalities is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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