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   479篇
  免费   28篇
  国内免费   3篇
电工技术   15篇
化学工业   115篇
金属工艺   16篇
机械仪表   11篇
建筑科学   15篇
矿业工程   1篇
能源动力   17篇
轻工业   57篇
水利工程   6篇
无线电   60篇
一般工业技术   101篇
冶金工业   58篇
原子能技术   4篇
自动化技术   34篇
  2024年   3篇
  2023年   5篇
  2022年   17篇
  2021年   26篇
  2020年   16篇
  2019年   15篇
  2018年   23篇
  2017年   19篇
  2016年   12篇
  2015年   15篇
  2014年   16篇
  2013年   45篇
  2012年   22篇
  2011年   19篇
  2010年   28篇
  2009年   12篇
  2008年   15篇
  2007年   25篇
  2006年   9篇
  2005年   12篇
  2004年   12篇
  2003年   11篇
  2002年   9篇
  2001年   9篇
  2000年   4篇
  1999年   7篇
  1998年   18篇
  1997年   14篇
  1996年   7篇
  1995年   5篇
  1994年   4篇
  1993年   6篇
  1992年   6篇
  1991年   4篇
  1987年   3篇
  1986年   3篇
  1985年   5篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
  1980年   3篇
  1979年   1篇
  1978年   3篇
  1977年   2篇
  1976年   4篇
  1974年   3篇
  1973年   2篇
  1967年   1篇
  1964年   1篇
排序方式: 共有510条查询结果,搜索用时 0 毫秒
51.
52.
The objective of this study was to formulate and develop a good quality cottage cheese dressing using acid whey as the main ingredient. Up to 72% of cottage cheese whey was used in the dressing mixes. The percentage of fat (4.10–5.05%) and total solids (19.41–20.24%) approached the desired level and was within the legal limits for regular cottage cheese. Sensory evaluation scores for flavour, body/texture and appearance were not adversely affected by the use of acid whey. The sensory evaluation scores for all four products made with whey- or skimmed milk-based dressings were higher than the commercial control.  相似文献   
53.
OBJECTIVE: To evaluate the histopathologic changes that occur in human small intestine or time when preserved in Viaspan organ preservation solution. DESIGN: Short segments of human small intestine were placed in standard organ preservation solution (Viaspan) and stored in conditions that mimic the clinical situation associated with clinical organ procurement, preservation, and transplantation. The intestinal segments were removed at sequential time points and placed in 10% formalin. Specimens underwent histopathologic examination to determine time-related changes. SPECIMENS: Short intestinal segments were obtained from seven multiorgan cadaver donors. Specimens were obtained in a way that exactly mimicked small intestinal organ retrieval. RESULTS: Small intestinal histology remained normal for the first 6 hours. After 6 hours, vacuolar separation began to occur between the epithelium and the basement membrane in the upper half of the villi. After 9 hours of cold preservation, epithelial detachment extended deep into the crypts with occasional shedding of cells and villi. CONCLUSIONS: Currently used small intestinal preservation using Viaspan results in considerable histopathologic changes in human jejunum after 9 hours of cold storage. The histopathologic pattern appears normal for the first 6 hours and suggests that preservation times should be limited to this time period when possible.  相似文献   
54.
This paper proposes a new control strategy of shunt flexible ac transmission system (FACTS) devices to improve the first swing stability limit of a simple power system. It is shown that the speed based bang-bang control (BBC) is unable to use the entire decelerating area in maintaining stability. The proposed control strategy improves the stability limit first by maximizing the decelerating area and then fully utilizing it in counterbalancing the accelerating area. This requires to continue the operation of shunt FACTS devices at full capacitive rating until the machine speed reaches a reasonable negative value during the first return journey. Afterwards, the control can be switched to continuous type to improve system damping in subsequent swings. The proposed control strategy is then applied to both static var compensator and static synchronous compensators placed in a single machine infinite bus system. The same control strategy is also used for some faults in a multimachine system. In both the systems, it is found that the proposed control can provide significantly higher stability limit than that of the BBC. The mechanism of improving the stability limit is also described.  相似文献   
55.
56.
The use of mobile phones while driving is more prevalent among young drivers—a less experienced cohort with elevated crash risk. The objective of this study was to examine and better understand the reaction times of young drivers to a traffic event originating in their peripheral vision whilst engaged in a mobile phone conversation. The CARRS-Q advanced driving simulator was used to test a sample of young drivers on various simulated driving tasks, including an event that originated within the driver's peripheral vision, whereby a pedestrian enters a zebra crossing from a sidewalk. Thirty-two licensed drivers drove the simulator in three phone conditions: baseline (no phone conversation), hands-free and handheld. In addition to driving the simulator each participant completed questionnaires related to driver demographics, driving history, usage of mobile phones while driving, and general mobile phone usage history. The participants were 21–26 years old and split evenly by gender. Drivers’ reaction times to a pedestrian in the zebra crossing were modelled using a parametric accelerated failure time (AFT) duration model with a Weibull distribution. Also tested where two different model specifications to account for the structured heterogeneity arising from the repeated measures experimental design. The Weibull AFT model with gamma heterogeneity was found to be the best fitting model and identified four significant variables influencing the reaction times, including phone condition, driver's age, license type (provisional license holder or not), and self-reported frequency of usage of handheld phones while driving. The reaction times of drivers were more than 40% longer in the distracted condition compared to baseline (not distracted). Moreover, the impairment of reaction times due to mobile phone conversations was almost double for provisional compared to open license holders. A reduction in the ability to detect traffic events in the periphery whilst distracted presents a significant and measurable safety concern that will undoubtedly persist unless mitigated.  相似文献   
57.
BACKGROUND: Protein conformational modifications and water‐protein interactions are two major factors believed to induce instability of protein and eventually affect the solubility of milk protein concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (aw 0.0–0.85) and temperatures (25 and 45 °C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in protein conformation by Fourier transform infrared (FTIR) spectroscopy and water status (interaction of water with the protein molecule/surface) by measuring the transverse relaxation time (T2) with proton nuclear magnetic resonance (1H NMR). RESULTS: The solubility of MPC decreased significantly with ageing and this process was enhanced by increasing water activity (aw) and temperature. Minor changes in protein secondary structure were observed with FTIR which indicated some degree of unfolding of protein molecules. The NMR T2 results indicated the presence of three distinct populations of water molecules and the proton signal intensity and T2 values of proton fractions varied with storage condition (humidity) and ageing. CONCLUSION: Results suggest that protein/protein interactions may be initiated by unfolding of protein molecules that eventually affects solubility. Copyright © 2011 Society of Chemical Industry  相似文献   
58.
59.
This study investigated the effect of soaking time on the quality of parboiled rice. The paddy was soaked in water at 25 and 80 °C for 15, 30, 45, 60 and 120 min. The soaked paddy was steamed, dried, stored and milled. With increasing soaking time a significant increase in water absorption and milling and head rice yield (hence reduction in broken rice) was observed. A significant difference in milling yield, at the 1% level, was obtained between the raw rice control and the hot soaked parboiled samples. A large reduction in fissured grain was observed after soaking. It is suggested that parboiling fills the void spaces and cements the cracks inside the endosperm, making the grain harder and minimizing internal fissuring and thereby breakage during milling.  相似文献   
60.
Mast cells (MC) are a key effector cell in multiple types of immune responses, including atopic conditions. Allergic diseases have been steadily rising across the globe, creating a growing public health problem. IgE-mediated activation of MCs leads to the release of potent mediators that can have dire clinical consequences. Current therapeutic options to inhibit MC activation and degranulation are limited; thus, a better understanding of the mechanisms that regulate MC effector functions in allergic inflammation are necessary in order to develop effective treatment options with minimal side effects. Several cytokines have been identified that play multifaceted roles in regulating MC activation, including TGFβ, IL-10, and IL-33, and others that appear to serve primarily anti-inflammatory functions, including IL-35 and IL-37. Here, we review the literature examining cytokines that regulate MC-mediated allergic immune responses.  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