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   506篇
  免费   35篇
综合类   6篇
化学工业   159篇
金属工艺   6篇
机械仪表   3篇
建筑科学   27篇
能源动力   15篇
轻工业   89篇
水利工程   5篇
石油天然气   2篇
无线电   14篇
一般工业技术   68篇
冶金工业   69篇
原子能技术   2篇
自动化技术   76篇
  2024年   1篇
  2023年   10篇
  2022年   32篇
  2021年   27篇
  2020年   13篇
  2019年   15篇
  2018年   10篇
  2017年   17篇
  2016年   24篇
  2015年   15篇
  2014年   23篇
  2013年   30篇
  2012年   37篇
  2011年   50篇
  2010年   26篇
  2009年   34篇
  2008年   25篇
  2007年   17篇
  2006年   16篇
  2005年   20篇
  2004年   10篇
  2003年   13篇
  2002年   11篇
  2001年   6篇
  2000年   5篇
  1999年   6篇
  1998年   5篇
  1997年   8篇
  1996年   5篇
  1995年   9篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1986年   3篇
  1984年   1篇
  1982年   2篇
  1979年   2篇
  1978年   1篇
  1977年   1篇
  1972年   1篇
排序方式: 共有541条查询结果,搜索用时 31 毫秒
531.
Adolescent girls with body dissatisfaction (N = 481, SD = 1.4) were randomized to a dissonance-based thin-ideal internalization reduction program, healthy weight control program, expressive writing control condition, or assessment-only control condition. Dissonance participants showed significantly greater decreases in thin-ideal internalization, body dissatisfaction, negative affect, eating disorder symptoms, and psychosocial impairment and lower risk for eating pathology onset through 2- to 3-year follow-up than did assessment-only controls. Dissonance participants showed greater decreases in thin-ideal internalization, body dissatisfaction, and psychosocial impairment than did expressive writing controls. Healthy weight participants showed greater decreases in thin-ideal internalization, body dissatisfaction, negative affect, eating disorder symptoms, and psychosocial impairment; less increases in weight; and lower risk for eating pathology and obesity onset through 2- to 3-year follow-up than did assessment-only controls. Healthy weight participants showed greater decreases in thin-ideal internalization and weight than did expressive writing controls. Dissonance participants showed a 60% reduction in risk for eating pathology onset, and healthy weight participants showed a 61% reduction in risk for eating pathology onset and a 55% reduction in risk for obesity onset relative to assessment-only controls through 3-year follow-up, implying that the effects are clinically important and enduring. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
532.
Carbonic anhydrase (CA) is an attractive biodegradable catalyst for CO2 absorption in solvent-based CO2 capture. However, maintaining the stability of CA as a homogeneous component of the solvents is a challenge. Solvent regeneration temperature typically exceeds the enzyme thermal tolerance, which leads to CA deactivation. To reduce the need for frequent CA replenishment and to avoid inactive CA accumulation in the solvent, this work shows the benefits of an immobilization strategy where CA is fixed in a second-generation design of textile structured packing (CATSP-2) modules. The enzyme-immobilized packing showed 1.5 times better performance in CO2 separation compared with traditional structured packing with a corresponding increased CO2 loading in the rich solvent. The modules exhibited good CA activity retention of ~80% during the tests without any CA replenishment. Applying CATSP-2 could potentially decrease the packing height and absorber column size for a lower cost per amount of CO2 captured.  相似文献   
533.
534.
Drawing on theorising on digital technologies as external enablers of entrepreneurial activities and an interactionist perspective on corporate entrepreneurship, this article examines the relationship between digital technology support and employee intrapreneurial behaviour. We propose that management support for innovation as an organisational characteristic and intrapreneurial self-efficacy as an individual characteristic moderate this relationship. Findings from a metric conjoint experiment with 1360 decisions nested within 85 employees showed that support by social media, support by collaborative technologies, and support by intelligent decision support systems were significant predictors of employee intrapreneurial behaviour. However, the relative impact of support by these digital technologies varied with different levels of management support for innovation and intrapreneurial self-efficacy.  相似文献   
535.
The targeted manipulation of polyketide synthases has in recent years led to numerous new-to-nature polyketides. For type I polyketide synthases the response of post-polyketide synthases (PKS) processing enzymes onto the most frequently polyketide backbone manipulations is so far insufficiently studied. In particular, complex processes such as the polyether cyclisation in the biosynthesis of ionophores such as monensin pose interesting objects of research. We present here a study of the substrate promiscuity of the polyether cyclisation cascade enzymes in monensin biosynthesis in the conversion of redox derivatives of the nascent polyketide chain. LC-HRMS/MS2-based studies revealed a remarkable flexibility of the post-PKS enzymes. They acted on derivatized polyketide backbones based on the three possible polyketide redox states within two different modules and gave rise to an altered polyether structure. One of these monensin derivatives was isolated and characterized by 2D-NMR spectroscopy, crystallography, and bioactivity studies.  相似文献   
536.
The interest in analytical methods that accurately measure or predict the elemental profile of dairy foods has been steadily rising. The purpose of this study was to assess the robustness of the energy-dispersive X-ray fluorescence (ED-XRF) technique for the prediction of mineral elements in milk and cheese, avoiding any sample preparation steps. Results highlighted relatively low accuracy of the ED-XRF technique for the quantification of milk mineral elements, with coefficients of determination in validation ( R v 2 ) from 0.03 (magnesium) to 0.39 (phosphorus). Greater accuracies were obtained for the quantification of cheese minerals, with R v 2 from 0.26 (sodium) to 0.69 (calcium).  相似文献   
537.
538.
Combining natural product fragments to design new scaffolds with unprecedented bioactivity is a powerful strategy for the discovery of tool compounds and potential therapeutics. However, the choice of fragments to couple and the biological screens to employ remain open questions in the field. By choosing a primary fragment containing the A/B ring system of estradiol and fusing it to nine different secondary fragments, we were able to identify compounds that modulated four different phenotypes: inhibition of autophagy and osteoblast differentiation, as well as potassium channel and tubulin modulation. The latter two were uncovered by using unbiased morphological profiling with a cell-painting assay. The number of hits and variety in bioactivity discovered validates the use of recombining natural product fragments coupled to phenotypic screening for the rapid identification of biologically diverse compounds.  相似文献   
539.
Di-ubiquitin (diUB) conjugates of defined linkages are useful tools for probing the functions of UB ligases, UB-binding proteins and deubiquitinating enzymes (DUBs) in coding, decoding and editing the signals carried by the UB chains. Here we developed an efficient method for linkage-specific synthesis of diUB probes based on the incorporation of the unnatural amino acid (UAA) Nϵ-L-thiaprolyl-L-Lys (L-ThzK) into UB for ligation with another UB at a defined Lys position. The diUB formed by the UAA-mediated ligation reaction has a G76C mutation on the side of donor UB for conjugation with E2 and E3 enzymes or undergoing dethiolation to generate a covalent trap for DUBs. The development of UAA mutagenesis for diUB synthesis provides an easy route for preparing linkage-specific UB-based probes to decipher the biological signals mediated by protein ubiquitination.  相似文献   
540.
The construction of custom libraries is critical for rational protein engineering and directed evolution. Array-synthesized oligo pools of thousands of user-defined sequences (up to ∼350 bases in length) have emerged as a low-cost commercially available source of DNA. These pools cost ≤10 % (depending on error rate and length) of other commercial sources of custom DNA, and this significant cost difference can determine whether an enzyme engineering project can be realized on a given research budget. However, while being cheap, oligo pools do suffer from a low concentration of individual oligos and relatively high error rates. Several powerful techniques that specifically make use of oligo pools have been developed and proven valuable or even essential for next-generation protein and pathway engineering strategies, such as sequence-function mapping, enzyme minimization, or de-novo design. Here we consolidate the knowledge on these techniques and their applications to facilitate the use of oligo pools within the protein engineering community.  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