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   688篇
  免费   37篇
电工技术   4篇
综合类   11篇
化学工业   219篇
金属工艺   8篇
机械仪表   11篇
建筑科学   42篇
矿业工程   4篇
能源动力   17篇
轻工业   164篇
水利工程   6篇
石油天然气   6篇
无线电   25篇
一般工业技术   79篇
冶金工业   68篇
原子能技术   4篇
自动化技术   57篇
  2023年   9篇
  2022年   21篇
  2021年   32篇
  2020年   16篇
  2019年   13篇
  2018年   23篇
  2017年   13篇
  2016年   19篇
  2015年   30篇
  2014年   29篇
  2013年   49篇
  2012年   29篇
  2011年   36篇
  2010年   31篇
  2009年   31篇
  2008年   44篇
  2007年   26篇
  2006年   32篇
  2005年   25篇
  2004年   29篇
  2003年   19篇
  2002年   21篇
  2001年   10篇
  2000年   10篇
  1999年   8篇
  1998年   8篇
  1996年   6篇
  1995年   11篇
  1994年   12篇
  1993年   4篇
  1992年   10篇
  1991年   6篇
  1990年   4篇
  1989年   3篇
  1988年   5篇
  1987年   2篇
  1986年   2篇
  1985年   3篇
  1983年   2篇
  1980年   2篇
  1979年   2篇
  1978年   4篇
  1977年   2篇
  1976年   2篇
  1975年   2篇
  1974年   2篇
  1968年   2篇
  1954年   1篇
  1948年   13篇
  1919年   1篇
排序方式: 共有725条查询结果,搜索用时 15 毫秒
81.
82.
Non‐invasive imaging holds significant potential for implementation in tissue engineering. It can be used to monitor the localization and function of tissue‐engineered implants, as well as their resorption and remodelling. Thus far, however, the vast majority of effort in this area of research have focused on the use of ultrasmall super‐paramagnetic iron oxide (USPIO) nanoparticle‐labeled cells, colonizing the scaffolds, to indirectly image the implant material. Reasoning that directly labeling scaffold materials might be more beneficial (enabling imaging also in the case of non‐cellularized implants), more informative (enabling the non‐invasive visualization and quantification of scaffold degradation), and easier to translate into the clinic (cell‐free materials are less complex from a regulatory point‐of‐view), three different types of USPIO nanoparticles are prepared and incorporated both passively and actively (via chemical conjugation; during collagen crosslinking) into collagen‐based scaffold materials. The amount of USPIO incorporated into the scaffolds is optimized, and correlated with MR signal intensity, showing that the labeled scaffolds are highly biocompatible, and that scaffold degradation can be visualized using MRI. This provides an initial proof‐of‐principle for the in vivo visualization of the scaffolds. Consequently, USPIO‐labeled scaffold materials seem to be highly suitable for image‐guided tissue engineering applications.  相似文献   
83.
84.
Since its medical legalization, cannabis preparations containing the major phytocannabinoids (cannabidiol (CBD) and δ9-tetrahydrocannabinol (THC)) have been used by patients with rheumatoid arthritis (RA) to alleviate pain and inflammation. However, minor cannabinoids such as cannabigerol (CBG) also demonstrated anti-inflammatory properties, but due to the lack of studies, they are not widely used. CBG binds several cellular target proteins such as cannabinoid and α2-adrenergic receptors, but it also ligates several members of the transient potential receptor (TRP) family with TRPA1 being the main target. TRPA1 is not only involved in nnociception, but it also protects cells from apoptosis under oxidative stress conditions. Therefore, modulation of TRPA1 signaling by CBG might be used to modulate disease activity in RA as this autoimmune disease is accompanied by oxidative stress and subsequent activation of pro-inflammatory pathways. Rheumatoid synovial fibroblasts (RASF) were stimulated or not with tumor necrosis factor (TNF) for 72 h to induce TRPA1 protein. CBG increased intracellular calcium levels in TNF-stimulated RASF but not unstimulated RASF in a TRPA1-dependent manner. In addition, PoPo3 uptake, a surrogate marker for drug uptake, was enhanced by CBG. RASF cell viability, IL-6 and IL-8 production were decreased by CBG. In peripheral blood mononuclear cell cultures (PBMC) alone or together with RASF, CBG-modulated interleukin (IL)-6, IL-10, TNF and immunoglobulin M and G production which was dependent on activation stimulus (T cell-dependent or independent). However, effects on PBMCs were only partially mediated by TRPA1 as the antagonist A967079 did inhibit some but not all effects of CBG on cytokine production. In contrast, TRPA1 antagonism even enhanced the inhibitory effects of CBG on immunoglobulin production. CBG showed broad anti-inflammatory effects in isolated RASF, PBMC and PBMC/RASF co-cultures. As CBG is non-psychotropic, it might be used as add-on therapy in RA to reduce IL-6 and autoantibody levels.  相似文献   
85.
Ohne ZusammenfassungMitteilung aus dem Pharmakognostischen Universitätsinstitut in Wien. (Vorstand: Privatdozent Dr. R. Wasicky.)  相似文献   
86.
Objective: Comprehensive review of studies using the choose-get-keep (CGK) process model of psychiatric rehabilitation. Also, other studies are identified that have demonstrated methodologies useful in future research on the CGK model. Intervention Model: The CGK process is conceptualized as the phases through which people with psychiatric disabilities proceed as they engage in psychiatric rehabilitation. Conclusion: The CGK model is a potentially useful psychiatric rehabilitation intervention that can be implemented in a variety of service settings and that focuses on the activities of the practitioner and the service recipient. The CGK model warrants further empirical study to examine its effectiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
87.
A simple, quantitative method for determining the plasmalogen content of small samples is reported here. The method uses the different susceptibility to acid-catalyzed hydrolysis of the alkyl, alkenyl and acyl linkages to separate the plasmalogen subclass from the other two non-labile subclasses. Hydrolysis of plasmenylethanolamine and plasmenylcholine was complete after 4 and 1 min of acid treatment, respectively. The acid-catalyzed hydrolysis did not alter the phospholipid fatty acid composition, making this method useful for fatty acid compositional analysis of the plasmalogen subclass. High-performance liquid chromatography was used for separations, and phospholipids were quantitated by assay of lipid phosphorus or by direct quantitation of peak area. Using this method, small amounts (10 nmol) of ethanolamine glycerophospholipid and choline glycerophospholipid are subjected to acid-catalyzed hydrolysis and subsequent separation of the resulting lysocompounds obtained from plasmalogens from the more acid-stable alkylacyl and diacyl glycerophospholipid fractions. Our values for plasmalogens from commercial preparations of choline and ethanolamine glycerophospholipids agree with literature values. The usefulness of the method is demonstrated for small glycerophospholipid samples that are equivalent to samples from cultured neural cells.  相似文献   
88.
This study focused to investigate the technological significance and the spoiling impact of diverse yeast strains, isolated from 'Bella di Cerignola' Italian table olives. Sixty-four isolates (belonging mainly to the species Candida famata and C. guilliermondii ) were studied to assess their growth at different temperatures (15, 25 and 37 °C), pHs (4.0, 5.0 and 9.5) and NaCl concentrations (0–10.0%) in lab medium. Their pectolytic, xylanolytic, lipolytic and catalase activities were also evaluated. Most of the yeasts showed a moderate pectolytic activity and were able to grow at pH 9.5 after 120 h of incubation. Salt and temperature were the most important environmental variables affecting yeast growth, which could exert a strong selective pressure on yeast population. Candida guilliermondii appeared more resistant to high salt concentrations, whereas C. famata was able to grow at 15 °C.  相似文献   
89.
Presented a character-classification task to 7 male college students under conditions of limited practice consistent with the characterization of memory search as a high-speed internal exhaustive serial comparison process having an average rate of 25-30 symbols/sec. Ss each performed under 3 positive set size conditions on each of 30 sessions. Results indicate that throughout sessions (a) the relationship between set size and response latency remained linear; (b) equality of slopes obtained from positive and negative trials was maintained; and (c) the estimate of scanning rate was stable, and its absolute value almost identical to previous values obtained with limited practice. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
90.
No population-based data are available on the degree to which Chinese Americans have adopted smoke-free household policies and whether these policies are effective in reducing environmental tobacco smoke (ETS) exposure. The present study examines the prevalence of smoke-free home rules among Chinese Americans living in New York City, describes predictors of adopting full smoking bans in the home, and explores the association between household smoking restrictions and ETS exposure at home. In-person interviews using a comprehensive household-based survey were conducted with 2,537 adults aged 18-74 years. Interviews were conducted in Mandarin, Cantonese, and other Chinese dialects. A total of 66% of respondents reported that smoking was not allowed inside the home, 22% reported a partial ban on smoking in the home, and 12% reported no smoking ban. Among current smokers, 38% reported a full household smoking ban. Current smoking status was the strongest predictor of less restrictive household smoking policies. Knowledge of the dangers of ETS, support of smoke-free air legislation, years in the United States, gender, income, and marital status also were associated with household smoking bans. Those living with a total household smoking ban were significantly less likely to report 30-day exposure to ETS than were those living in homes with a partial ban or no ban (7% vs. 68% and 73%, respectively). In homes of smokers and nonsmokers alike, exposure to ETS remains high. Smoke-free home rules and interventions among smokers and nonsmokers to raise awareness of the dangers of ETS have the potential to significantly reduce exposure to household ETS among this immigrant population.  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