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   460篇
  免费   29篇
电工技术   3篇
综合类   6篇
化学工业   118篇
金属工艺   4篇
机械仪表   3篇
建筑科学   37篇
矿业工程   1篇
能源动力   8篇
轻工业   80篇
水利工程   6篇
石油天然气   2篇
无线电   8篇
一般工业技术   80篇
冶金工业   58篇
原子能技术   1篇
自动化技术   74篇
  2023年   2篇
  2022年   6篇
  2021年   20篇
  2020年   12篇
  2019年   12篇
  2018年   10篇
  2017年   20篇
  2016年   20篇
  2015年   22篇
  2014年   12篇
  2013年   29篇
  2012年   27篇
  2011年   33篇
  2010年   20篇
  2009年   40篇
  2008年   22篇
  2007年   18篇
  2006年   20篇
  2005年   16篇
  2004年   14篇
  2003年   9篇
  2002年   15篇
  2001年   4篇
  2000年   5篇
  1999年   4篇
  1998年   4篇
  1997年   7篇
  1996年   8篇
  1995年   7篇
  1994年   6篇
  1993年   5篇
  1992年   2篇
  1991年   4篇
  1990年   4篇
  1989年   2篇
  1988年   1篇
  1987年   3篇
  1985年   4篇
  1984年   3篇
  1983年   1篇
  1982年   4篇
  1981年   3篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1977年   4篇
  1975年   1篇
排序方式: 共有489条查询结果,搜索用时 912 毫秒
451.
Azo dyes are widely used in industries and their release in the environment contributes to the pollution of effluents. The authors aim to develop a new eco‐friendly water treatment method for the degradation of azo dyes based on in situ magnetic separation and immobilisation of bacterial cells. The immobilisation was achieved using superparamagnetic Fe3 O4 nanoparticles and offers the possibility of reusing bacteria by magnetic separation for several degradation cycles. The iron oxide nanoparticles were synthesised by reverse co‐precipitation. The Gram‐positive bacteria Bacillus subtilis were immobilised using iron–oxide nanoparticles by adsorption and then separated with an external magnetic field. Transmission electron microscopy observation showed that the particles'' diameter was ∼20 nm with a narrow size distribution. Moreover, the iron–oxide nanoparticles were adsorbed onto the surface in order to coat the cells. B. subtilis has proved its ability to decolorise and degrade several azo dyes at different values of pH, with the highest decolorisation rate for Congo red. Furthermore, immobilised cells have a degradation activity similar to that of free cells. The system provided a degradation rate up to 80% and could be reused for seven batch cycles.Inspec keywords: biotechnology, microorganisms, pH, adsorption, iron compounds, superparamagnetism, transmission electron microscopy, ultraviolet spectra, chemical technology, wastewater treatment, effluents, dyes, magnetic separation, iron, magnetic particles, decontaminationOther keywords: degradation rate, immobilisation, magnetic nanoparticles, azo dyes, eco‐friendly water treatment method, degradation cycles, Gram‐positive bacteria, iron–oxide nanoparticles, external magnetic field, immobilised cells, degradation activity, magnetic separation, effluents, bacterial cells, Fe3 O4   相似文献   
452.
[Correction Notice: An erratum for this article was reported in Vol 24(3) of Psychology and Aging (see record 2009-13203-014). An incorrect Figure 1 was printed due to an error in the production process. The correct version is presented in the erratum.] Development does not take place in isolation; close others form an important dyad for exploring interrelationships. To examine spousal interrelations in level and change of cognitive functioning in old age, the authors applied dynamic models to 11-year longitudinal data of, initially, 304 married couples from the Australian Longitudinal Study of Ageing (aged 64–98 years at Time 1; M = 76 years). Findings revealed that perceptual speed for husbands predicted subsequent perceptual speed decline for wives (time lags of 1 year). There was little evidence for the opposite unidirectional effect or a bidirectional association between husbands and wives. Potential covariates (age, education, medical conditions, functional limitations, and depressive symptoms) did not account for differential lead–lag associations. A similar, though less pronounced, pattern was found for memory, which held except when functional limitations were controlled. Findings suggest that late-life cognitive development is not solely a product of intraindividual resources and are consistent with conceptual notions that development actively influences, and is influenced by, contextual factors such as close relationships. The authors discuss possible underlying mechanisms and further steps to substantiate the findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
453.
Several streptocyanine dyes were synthesized that contain polymethine chains of varying length. Their in vitro antimalarial activities were evaluated against the virulent P. falciparum parasite. In addition to the influence of polymethine chain length, the effects of structural modifications at nitrogen end groups, para substitution of the phenyl groups, and counter‐anions were studied. The most potent antimalarial activities were found for heptacarbon chain streptocyanines, with an IC50 value of 60 nM . Interestingly, most of the compounds were less cytotoxic toward the mammalian cells tested. The best selective toxicity profiles were found for pentacarbon chain streptocyanines, which have a good in vitro specificity index.  相似文献   
454.
455.
456.
457.
Olfactory behavioral studies have shown that, when modulated through systemic injections, D1 and D2 receptors have opposing effects on odor discrimination learning. In the present study, cannulated male Sprague–Dawley rats were used to investigate how the modulation of these 2 types of dopaminergic receptors through direct infusion of D1/D2 agonists and antagonists into the olfactory bulb affect olfactory perception. Dopaminergic modulation was locally altered by manipulations of D1 (agonist SKF 82958: 14.6, 43.8, & 143.6 mM; antagonist SCH-23390: 13.4, 40.1, & 60.1 mM) and D2 (agonists quinpirole: 78.2, 117.3, & 156.4 mM; antagonist sulpiride: 0.3, 0.9, & 2.9 mM) receptors during a simultaneous odor discrimination task. The authors found that modulation of D2, but not D1, receptors significantly affected rats’ odor discrimination performance. A significant positive correlation between blockade of D2 receptors and discrimination performance, as well as a significant negative correlation between D2 receptor activation and discrimination performance, was observed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
458.
Brazil is a highlight in the ranking of maize cooking oil production, which after consumption generates a significant amount of waste that the improper disposal of it, which could seriously affect the sewage pipes, groundwater, and soil. This research study the incorporation of 1%, 2%, and 3% of soybean (new and waste) in asphalt binder. The samples were analyzed by FTIR and frequency sweep tests. The results indicate that the optimum oil content is in the range of 1–2%, regardless of being new or residual. In the temperature sweep, it was found that the asphalt binder 55/75-E showed a smaller phase angle in all mixtures compared to the asphalt binder 50/70, thus having a better elastic recovery.  相似文献   
459.
Adults with attention-deficit/hyperactivity disorder (ADHD) are predisposed to smoking, but the neuropsychological correlates of this association have not been elucidated so far. The present study evaluates possible associations between cognitive performance and smoking and other comorbidities in adults with ADHD. Two hundred and sixty-four (264) patients were evaluated in the adult ADHD outpatient clinic of the Hospital de Clínicas de Porto Alegre. The diagnoses were based on the DSM-IV criteria and interviews were performed with the Portuguese version of K-SADS-E for ADHD and oppositional-defiant disorder. Axis I psychiatric comorbidities were evaluated with the SCID-IV and the cognitive performance with the Vocabulary and Block Design subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS-R). The evaluation of the influence of the WAIS-R scores on each dependent variable was performed with logistic regression analyses. Lower scores in the Block Design subtest of WAIS-R were associated with smoking and the presence of anxiety disorder. These results suggest that a subgroup of ADHD patients with lower Block Design subtest scores may be at increased risk of smoking as a cognitive enhancement. Our findings also confirmed the previously suggested association between anxiety and lower Block Design scores.  相似文献   
460.
A role for HE6/GPR64 in male excurrent ducts in the regulation of water balance was suggested from targeted gene mutation in the mouse. Results of the present immunolocalization study strengthen this hypothesis. Employing monospecific antibodies and laser confocal microscopy, we studied the localization of the receptor protein in the human and wild-type mouse ductuli efferentes and epididymis. We show that HE6/GPR64 is specifically associated with cell types and subcellular domains involved in the process of fluid reabsorption. In the mouse, dual labelling with anti-tubulin antibodies revealed that HE6/GPR64 was absent from the (kino-) cilia of ciliated cells. Instead, the receptor protein accumulated in the non-ciliated principal cells. Specifically, strong immunofluorescence was observed in the apical compartment of these cells. Dual labelling with phalloidin and anti-ezrin antibodies revealed that in the mouse the bulk amount of HE6/GPR64 protein co-localized with the F-actin-ezrin scaffold in brush border-like microvilli of ductuli efferentes and long stereocilia of the epididymis proper. In the ductuli efferentes, HE6/GPR64 also co-localized with the subapical F-actin network immediately below the microvilli. Comparable immunostaining patterns were observed in human and mouse; however, a specific feature of the human ductuli efferentes was an intense HE6/GPR64-related labelling of crypt-like grooves or furrows of hitherto unknown function.  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