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   1463篇
  免费   136篇
  国内免费   34篇
电工技术   22篇
综合类   47篇
化学工业   338篇
金属工艺   80篇
机械仪表   91篇
建筑科学   104篇
矿业工程   8篇
能源动力   91篇
轻工业   268篇
水利工程   20篇
石油天然气   17篇
武器工业   11篇
无线电   97篇
一般工业技术   141篇
冶金工业   93篇
原子能技术   13篇
自动化技术   192篇
  2024年   7篇
  2023年   19篇
  2022年   42篇
  2021年   47篇
  2020年   46篇
  2019年   37篇
  2018年   29篇
  2017年   54篇
  2016年   66篇
  2015年   51篇
  2014年   69篇
  2013年   132篇
  2012年   89篇
  2011年   105篇
  2010年   68篇
  2009年   78篇
  2008年   68篇
  2007年   99篇
  2006年   69篇
  2005年   58篇
  2004年   67篇
  2003年   49篇
  2002年   38篇
  2001年   29篇
  2000年   23篇
  1999年   21篇
  1998年   20篇
  1997年   18篇
  1996年   22篇
  1995年   16篇
  1994年   8篇
  1993年   9篇
  1992年   8篇
  1991年   7篇
  1990年   5篇
  1989年   12篇
  1988年   6篇
  1987年   4篇
  1986年   7篇
  1985年   7篇
  1984年   5篇
  1983年   4篇
  1981年   2篇
  1978年   1篇
  1972年   1篇
  1967年   2篇
  1965年   1篇
  1964年   2篇
  1959年   1篇
  1955年   2篇
排序方式: 共有1633条查询结果,搜索用时 31 毫秒
991.
Consumers’ preference to have a healthy eating pattern has led to an increasing demand for more nutrient-dense and healthier plant-based foods. Pulse proteins are exceptional quality ingredients with potential nutritional benefits, and might act as health-promoting agents for addressing the new-generation foods. However, the utilization of pulse protein in foods has been hampered by its relatively poor functionality and unpleasant flavor. Protein structure modification has been proved to be a useful means to improve the functionality and flavor profile of pulse protein. This paper begins with a brief introduction of hierarchical structure of pulse protein materials to better understand the structure characteristics. A comprehensive review is presented on the current techniques including chemical and enzymatic modifications and molecular breeding on pulse protein structure and functionality/flavor. The mechanism and the limitations and the toxicological concerns of these approaches are discussed. We conclude that understanding protein structure‒functionality relationship is extremely valuable in tailoring proteins for specific functional outcomes and expanding the availability of pulse proteins. Furthermore, selective protein modification is a valuable in-depth toolkit for generating novel protein constructs with preferable functional attributes and flavor profiles. Innovative structure modification with special focus on the molecular basis for the exquisite protein designs is a pillar of pulse protein access to the desired functionality.  相似文献   
992.
This paper presents a methodology to provide information to a decision maker on the associated impacts, both of economic and technical nature, of possible management schemes of storage units for choosing the best location of distributed storage devices, with a multiobjective optimisation approach based on genetic algorithms. The methodology was applied to a case study, a known distribution network model in which the installation of distributed storage units was tested, using lithium-ion batteries. The obtained results show a significant influence of the charging/discharging profile of batteries on the choice of their best location, as well as the relevance that these choices may have for the different network management objectives, for example, for reducing network energy losses or minimising voltage deviations. Results also show a difficult cost-effectiveness of an energy-only service, with the tested systems, both due to capital cost and due to the efficiency of conversion.  相似文献   
993.
The diffusion-weighted imaging (DWI) technique can be utilized to investigate a variety of diseases. We propose an automated pilot system, which assists in the diagnosis of metabolic brain diseases, utilizing the DWI. In this study, DWI images are preprocessed and exponential apparent diffusion coefficient (eADC) images are produced. The eADC images are later brain extracted and normalized to a standard brain template. Subsequently, we utilized wavelets to denoise the eADC images. The images are rectified, thresholded and now conspicuous abnormal regions are subsequently identified utilizing different brain atlases. Abnormal regions constitute the features that will be used by a fuzzy relational classifier in order to categorize the diseases. A sensitivity and specificity of 60% and 93.33%, respectively, in detecting metabolic brain diseases have been achieved.  相似文献   
994.
Computer programming ability is a type of knowledge that is considered to be quite complex because it demands many cognitive skills and extensive practice to be mastered. However, formative assessment is a strategy that can improve learning. For this reason, we developed a recommender system to aid in making choices on programming practices by recommending classes of activities. This system provides instructors with a means of semi-automatic assessment, with more individualised and accurate activities tailored to the needs of their learners. To achieve this goal, the system of recommendations analyses multidimensional profiles of new students and seeks the best match for them among profiles in the logs of previous recommendations, which were made manually. Based on these matched profiles, the system can now recommend to new learners classes of activities that are indicated by similar profiles that have already received recommendations. The recommendation of activities is thus treated by our system as a multi-label classification task in which each student’s profile is associated with one or more classes of programming activities. The results obtained under different evaluation metrics confirm that the chosen algorithm, the ML-kNN, correctly mimics human decisions on the recommendations of classes of activities most of the time. Furthermore, these metrics provide relevant information for instructors to perform better actions with regard to formative assessments.  相似文献   
995.
Comparing two suppliers for linear profiles is a very important task for supplier management. The difference test statistic based on the process‐yield index is proposed to tackle the better process selection for linear profiles. A simple form of the sampling distribution of the process‐yield index is derived by a simulation study. Therefore, the asymptotic normal distribution of the difference test statistic is established. The results provide useful information to practitioners. An example from the leather industry is presented to illustrate the applicability of the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
996.
BackgroundAlterations in gut microbiota composition and bacterial metabolites have been increasingly recognized to affect host metabolism and are at the basis of metabolic diseases such as obesity and type 2 diabetes (DM2). Intestinal enteroendocrine cells (EEC's) sense gut luminal content and accordingly secrete hormones that modulate glucose and lipid metabolism and affect satiety. It has become evident that microbial metabolic products significantly affect EEC function.Scope and approachIn this review, we will discuss current insights in the role of the gut microbiota and its metabolites in development of obesity and DM2 and elaborate on interventions that modulate EEC action.Key findings and conclusionsStudies including fecal transplantation and Roux-en-Y gastric bypass (RYGB) in humans and animal models suggest that the gut microbiota and its metabolites causally contribute to development of obesity and DM2. Emerging evidence suggests that the gut microbiota and its metabolites can modulate secretion of EEC hormones that regulate appetite and insulin secretion. Dispersed intestinal expression and low abundance make EEC's difficult to study. Since current intestinal sampling methods in humans are mostly limited to the colon, this leaves a large part of EEC function understudied. It would therefore be relevant to develop means to extend sampling methods throughout to entire GI tract.  相似文献   
997.
998.
This study examined some physicochemical properties of actomyosin isolated from pre-rigor chicken breast muscle (Pectoralis major) to gain insight on its interaction with 0.2–1.0M sodium bicarbonate (NaHCO3) either with or without 3% sodium chloride (NaCl). NaHCO3 has been a frequent quality raiser with respect to water holding capacity of meat, which is adversely affected at low pH. This study document a remarkable inactivation of ATPases and the weakening of actin-myosin interaction with increasing molarity of NaHCO3, irrespective of the presence or absence of NaCl. Similarly, there was a concomitant increase in turbidity of soluble fraction, increase in total protein solubility and reactive SH groups. The observations on protein solubility/insolubility are supported by SDS-PAGE profiles. Therefore, the conformational changes induced by NaHCO3 are concentration dependent and appear different from those during thermal transitions. The findings suggest that low concentration of NaHCO3 may be more suitable component of marinades, since it affects the main myofibrillar contractile complex less adversely.  相似文献   
999.
A polyanhydride implant containing gentamicin sulfate was fabricated using a laboratory‐scale injection‐molding machine. After injection molding, the implants were subject to heat treatment at 60°C for various time periods with or without nitrogen protection. The impact of this heat treatment on the in vitro properties of the implants including copolymer molecular weights, mechanical properties, and in vitro drug‐release profiles was investigated. This heat treatment caused a drastic drop in the molecular weight of the copolymer. Heating without nitrogen protection resulted in the hardening of the implant, but heating in the presence of nitrogen rendered the implant less rigid. It was also found that a faster in vitro drug release profile was shown by implants heated without nitrogen protection and a pronounced slowing down in drug release was exhibited by implants heated with nitrogen protection.  相似文献   
1000.
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