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   1394篇
  免费   73篇
  国内免费   3篇
电工技术   10篇
综合类   3篇
化学工业   402篇
金属工艺   22篇
机械仪表   19篇
建筑科学   72篇
能源动力   17篇
轻工业   210篇
水利工程   16篇
石油天然气   2篇
无线电   105篇
一般工业技术   224篇
冶金工业   202篇
原子能技术   10篇
自动化技术   156篇
  2024年   5篇
  2023年   25篇
  2022年   68篇
  2021年   87篇
  2020年   53篇
  2019年   33篇
  2018年   44篇
  2017年   36篇
  2016年   45篇
  2015年   49篇
  2014年   45篇
  2013年   83篇
  2012年   102篇
  2011年   101篇
  2010年   75篇
  2009年   81篇
  2008年   104篇
  2007年   68篇
  2006年   49篇
  2005年   42篇
  2004年   36篇
  2003年   37篇
  2002年   25篇
  2001年   24篇
  2000年   12篇
  1999年   21篇
  1998年   13篇
  1997年   13篇
  1996年   15篇
  1995年   8篇
  1994年   8篇
  1993年   7篇
  1992年   7篇
  1991年   1篇
  1990年   4篇
  1989年   6篇
  1988年   1篇
  1987年   11篇
  1986年   5篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   6篇
  1981年   1篇
  1980年   2篇
  1979年   4篇
  1976年   3篇
  1968年   1篇
排序方式: 共有1470条查询结果,搜索用时 0 毫秒
21.
The present research was conducted to clarify the relationships among social anxiety, alcohol consumption, alcohol-related problems, and negative-reinforcement drinking motives among college students. Heavy drinking students (N = 316, 53.80% female) completed self-report measures of social anxiety, alcohol consumption, alcohol-related problems, and drinking motives. Findings indicated that students higher in social anxiety consumed less alcohol but experienced more negative consequences. Moreover, the relationship between social anxiety and negative consequences was mediated by coping and conformity drinking motives in addition to alcohol consumption. In the context of social anxiety, the current research demonstrates the importance of examining problematic drinking as distinct constructs: alcohol consumption and negative consequences. Findings are also discussed in terms of implications for interventions with socially anxious students. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
22.
Maternal obesity predisposes for hepato-metabolic disorders early in life. However, the underlying mechanisms causing early onset dysfunction of the liver and metabolism remain elusive. Since obesity is associated with subacute chronic inflammation and accelerated aging, we test the hypothesis whether maternal obesity induces aging processes in the developing liver and determines thereby hepatic growth. To this end, maternal obesity was induced with high-fat diet (HFD) in C57BL/6N mice and male offspring were studied at the end of the lactation [postnatal day 21 (P21)]. Maternal obesity induced an obese body composition with metabolic inflammation and a marked hepatic growth restriction in the male offspring at P21. Proteomic and molecular analyses revealed three interrelated mechanisms that might account for the impaired hepatic growth pattern, indicating prematurely induced aging processes: (1) Increased DNA damage response (γH2AX), (2) significant upregulation of hepatocellular senescence markers (Cdnk1a, Cdkn2a); and (3) inhibition of hepatic insulin/insulin-like growth factor (IGF)-1-AKT-p38-FoxO1 signaling with an insufficient proliferative growth response. In conclusion, our murine data demonstrate that perinatal obesity induces an obese body composition in male offspring with hepatic growth restriction through a possible premature hepatic aging that is indicated by a pathologic sequence of inflammation, DNA damage, senescence, and signs of a possibly insufficient regenerative capacity.  相似文献   
23.
The ocular surface is in constant interaction with the environment and with numerous pathogens. Therefore, complex mechanisms such as a stable tear film and local immune defense mechanisms are required to protect the eye. This study describes the detection, characterization, and putative role of surfactant protein G (SP-G/SFTA2) with respect to wound healing and surface activity. Bioinformatic, biochemical, and immunological methods were combined to elucidate the role of SP-G in tear film. The results show the presence of SP-G in ocular surface tissues and tear film (TF). Increased expression of SP-G was demonstrated in TF of patients with dry eye disease (DED). Addition of recombinant SP-G in combination with lipids led to an accelerated wound healing of human corneal cells as well as to a reduction of TF surface tension. Molecular modeling of TF suggest that SP-G may regulate tear film surface tension and improve its stability through specific interactions with lipids components of the tear film. In conclusion, SP-G is an ocular surface protein with putative wound healing properties that can also reduce the surface tension of the tear film.  相似文献   
24.
25.
A meta-analysis of 26 published articles (with 36 independent participant groups) was conducted to analyze the relationship between task-switching effects and aging. Latency served as the dependent measure. Multilevel modeling was used to test for additive and multiplicative complexity effects in local and global switch costs. Global task switching was found to add 1 or more stages to processing and resulted in a marked age deficit. Local task-switching costs, on the other hand, showed a multiplicative complexity effect but no specific attention-related age deficits. Cueing or switch predictability did not affect age differences. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
26.
ABSTRACT

The efficacy of climate-change mitigation policy within the building sector is examined in terms of how fragmentation can limit the extent of mitigation actions that can be achieved in a timely manner. The policy and regulatory context for the building industry is examined in relation to the policy context for solutions and recommendations that will work for all parties. Based on this analysis, two substantive recommendations are made for improved policy design. Firstly, a decoupling of policy objectives and policy mechanisms is needed so that the policy-taking stakeholders (in design, development and construction) can reduce energy use in buildings more effectively. Secondly, policy-taking stakeholders need an explicit and diverse system in order to advocate for policy objectives. The major aspect of this work is the development of a new conceptual framework that ties together these recommendations into a continuous process of policy-making and policy-taking. This framework demonstrates an idealized system that operates simultaneously top down and bottom up, and the development of policy objectives is influenced by stakeholders of all kinds to further the goals of an energy-efficient, low-carbon built environment.  相似文献   
27.
Enfuvirtide (ENF) is a fusion inhibitor that prevents the entry of HIV virions into target cells. Studying the characteristics of viral evolution during treatment and after a treatment interruption can lend insight into the mechanisms of viral evolution and fitness. Although interruption of anti-HIV therapy often results in rapid emergence of an archived “wild-type” virus population, previous work from our group indicates that when only ENF is interrupted, viral gp41 continues to evolve forward and resistance mutations are lost due to back-mutation and remodeling of the envelope protein. To examine the co-evolution of gp120 and gp41 during ENF interruption we extend the Bayesian Hierarchical Phylogenetic model (HPM). Current HPMs enforce conditional independence across all outcomes while biologically all gene regions within a patient should return the same tree unless recombination confers an evolutionary selective advantage. A two-way-interaction HPM is proposed that provides middle ground between these two extremes and allows us to test for differences in evolutionary pressures across gene regions in multiple patients simultaneously. When the model is applied to a well-characterized cohort of HIV-infected patients interrupting ENF we find that across patients, the virus continued to evolve forward in both gene regions. Overall, the hypothesis of independence over dependence between the gene regions is supported. Models that allow for the examination of co-evolution over time will be increasingly important as more therapeutic classes are developed, each of which may impact other through novel and complex mechanisms.  相似文献   
28.
29.
Excess dietary fructose is a major public health concern, yet little is known about its influence on offspring development and later-life disease when consumed in excess during pregnancy. To determine whether increased maternal fructose intake could have long-term consequences on offspring health, we investigated the effects of 10% w/v fructose water intake during preconception and pregnancy in guinea pigs. Female Dunkin Hartley guinea pigs were fed a control diet (CD) or fructose diet (FD; providing 16% of total daily caloric intake) ad libitum 60 days prior to mating and throughout gestation. Dietary interventions ceased at day of delivery. Offspring were culled at day 21 (D21) (weaning) and at 4 months (4 M) (young adult). Fetal exposure to excess maternal fructose intake significantly increased male and female triglycerides at D21 and 4 M and circulating palmitoleic acid and total omega-7 through day 0 (D0) to 4 M. Proteomic and functional analysis of significantly differentially expressed proteins revealed that FD offspring (D21 and 4 M) had significantly increased mitochondrial metabolic activities of β-oxidation, electron transport chain (ETC) and oxidative phosphorylation and reactive oxygen species production compared to the CD offspring. Western blotting analysis of both FD offspring validated the increased protein abundances of mitochondrial ETC complex II and IV, SREBP-1c and FAS, whereas VDAC1 expression was higher at D21 but lower at 4 M. We provide evidence demonstrating offspring programmed hepatic mitochondrial metabolism and de novo lipogenesis following excess maternal fructose exposure. These underlying asymptomatic programmed pathways may lead to a predisposition to metabolic dysfunction later in life.  相似文献   
30.
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