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   405篇
  免费   15篇
  国内免费   1篇
电工技术   3篇
化学工业   162篇
机械仪表   1篇
建筑科学   16篇
矿业工程   1篇
能源动力   3篇
轻工业   94篇
水利工程   3篇
石油天然气   1篇
无线电   15篇
一般工业技术   55篇
冶金工业   17篇
原子能技术   1篇
自动化技术   49篇
  2024年   2篇
  2023年   7篇
  2022年   38篇
  2021年   46篇
  2020年   24篇
  2019年   14篇
  2018年   11篇
  2017年   16篇
  2016年   17篇
  2015年   18篇
  2014年   18篇
  2013年   22篇
  2012年   19篇
  2011年   30篇
  2010年   20篇
  2009年   9篇
  2008年   19篇
  2007年   16篇
  2006年   13篇
  2005年   10篇
  2004年   7篇
  2003年   8篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1999年   3篇
  1998年   1篇
  1997年   2篇
  1996年   3篇
  1995年   1篇
  1994年   4篇
  1993年   2篇
  1992年   4篇
  1989年   5篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1972年   1篇
排序方式: 共有421条查询结果,搜索用时 15 毫秒
81.
Among mammals, serotonin is predominantly found in the gastrointestinal tract, where it has been shown to participate in pathway-regulating satiation. For the stomach, vascular serotonin release induced by gastric distension is thought to chiefly contribute to satiation after food intake. However, little information is available on the capability of gastric cells to synthesize, release and respond to serotonin by functional changes of mechanisms regulating gastric acid secretion. We investigated whether human gastric cells are capable of serotonin synthesis and release. First, HGT-1 cells, derived from a human adenocarcinoma of the stomach, and human stomach specimens were immunostained positive for serotonin. In HGT-1 cells, incubation with the tryptophan hydroxylase inhibitor p-chlorophenylalanine reduced the mean serotonin-induced fluorescence signal intensity by 27%. Serotonin release of 147 ± 18%, compared to control HGT-1 cells (set to 100%) was demonstrated after treatment with 30 mM of the satiating amino acid L-Arg. Granisetron, a 5-HT3 receptor antagonist, reduced this L-Arg-induced serotonin release, as well as L-Arg-induced proton secretion. Similarly to the in vitro experiment, human antrum samples released serotonin upon incubation with 10 mM L-Arg. Overall, our data suggest that human parietal cells in culture, as well as from the gastric antrum, synthesize serotonin and release it after treatment with L-Arg via an HTR3-related mechanism. Moreover, we suggest not only gastric distension but also gastric acid secretion to result in peripheral serotonin release.  相似文献   
82.
    
Synchronous collaboration sessions within the context of 4D BIM position construction professionals into a complex socio–technical system. This system includes hardware, software, people, and broader community aspects. This article strictly focuses on the ontology representation of synchronous collaboration sessions with collocated collective decision-making. The model is designed by considering various 4D BIM model uses while a digital multiuser touch table facilitates the collaboration between actors. The outlined ontological model aims to improve interoperability and to move toward a knowledge-driven, smart-built environment paradigm. A knowledge engineering methodology is outlined, by virtue of which the semantics of the presented model are defined and discussed. Concepts from nearby knowledge fields, especially from the Industry Foundation Classes, are reused. Several examples on querying the knowledge base according to the project meeting requirements are outlined to demonstrate the benefits of using the model. Although 4D BIM model data can be imported by using standard formats, capturing data about the social context remains a challenge in the future. This is expected to change the ontology model structure by considering user ergonomics, data modeling requirements, as well as technical implementation constraints.  相似文献   
83.
    
Hydropower contributes to a higher share of renewables but is also in conflict with environmental legislation aiming to protect natural habitats, wildlife and endangered species. Analysing two neighbouring European countries with similar topographical and hydromporphological characteristics, Austria and Slovenia, allows assessing to what extent a policies’ national context steers possible policy conflicts of EU legislation. The paper shows that hydropower expansion in examined countries is strongly shaped by factors such as financial concerns of investors, diverging opinions of involved stakeholders, available hydro potential and the role of hydropower in national energy strategies. Addressing issues that lead to a lower effectiveness of national policies already at the level of EU policy design or engaging countries to broadening their national energy portfolio by considering emerging technologies such as PV and wind will enable future energy and climate strategies that are more consistent with other environmental goals.  相似文献   
84.
    
The coexistence of cancer and other concomitant diseases is very frequent and has substantial implications for treatment decisions and outcomes. Beta-blockers, agents that block the beta-adrenergic receptors, have been related also to cancers. In the model of multicellular spheroids formed by colorectal cancer cells we described a crosstalk between beta-blockade by propranolol and tumour microenvironment. Non-selective beta-blocker propranolol decreased ability of tumour cells to adapt to hypoxia by reducing levels of HIF1α and carbonic anhydrase IX in 3D spheroids. We indicated a double action of propranolol in the tumour microenvironment by inhibiting the stability of HIF1α, thus mediating decrease of CA IX expression and, at the same time, by its possible effect on CA IX activity by decreasing the activity of protein kinase A (PKA). Moreover, the inhibition of β-adrenoreceptors by propranolol enhanced apoptosis, decreased number of mitochondria and lowered the amount of proteins involved in oxidative phosphorylation (V-ATP5A, IV-COX2, III-UQCRC2, II-SDHB, I-NDUFB8). Propranolol reduced metastatic potential, viability and proliferation of colorectal cancer cells cultivated in multicellular spheroids. To choose the right treatment strategy, it is extremely important to know how the treatment of concomitant diseases affects the superior microenvironment that is directly related to the efficiency of anti-cancer therapy  相似文献   
85.
    
Breast cancer is the most common cancer in women in the world. The role of germline genetic variability in ATP-binding cassette (ABC) transporters in cancer chemoresistance and prognosis still needs to be elucidated. We used next-generation sequencing to assess associations of germline variants in coding and regulatory sequences of all human ABC genes with response of the patients to the neoadjuvant cytotoxic chemotherapy and disease-free survival (n = 105). A total of 43 prioritized variants associating with response or survival in the above testing phase were then analyzed by allelic discrimination in the large validation set (n = 802). Variants in ABCA4, ABCA9, ABCA12, ABCB5, ABCC5, ABCC8, ABCC11, and ABCD4 associated with response and variants in ABCA7, ABCA13, ABCC4, and ABCG8 with survival of the patients. No association passed a false discovery rate test, however, the rs17822931 (Gly180Arg) in ABCC11, associating with response, and the synonymous rs17548783 in ABCA13 (survival) have a strong support in the literature and are, thus, interesting for further research. Although replicated associations have not reached robust statistical significance, the role of ABC transporters in breast cancer should not be ruled out. Future research and careful validation of findings will be essential for assessment of genetic variation which was not in the focus of this study, e.g., non-coding sequences, copy numbers, and structural variations together with somatic mutations.  相似文献   
86.
87.
88.
    
Oriented organic layers have great potential for organic electronics devices because of the unique modification of material properties without extensive chemical synthesis. Such layers can be prepared by wet coating of anisotropic organic molecules on top of specific surface of alignment layer. One of the most important parameter that indicates alignment properties of the surface is the anchoring energy. In this paper, we investigate azimuthal anchoring energy of pure and glycerol‐doped PEDOT : PSS layers and study the influence of the alignment layer preparation on the order parameter of the top wet‐coated oriented organic emitter. We confirm that the azimuthal anchoring energy increase leads to improvement of both dichroic ratio and contrast ratio of polarized emitter layer rod‐coated on top of the PEDOT : PSS. Suggested mechanism of anisotropic emitter formation at wet deposition grounds possibility of linear deposition rate of 2 m/s on top of PEDOT : PSS layer with obtained azimuthal anchoring above >10?4 J/m2.  相似文献   
89.
90.
    
The vat dyeing process of specific fabrics with protective, inherently fire retardant properties that have a high content of aramid fibres in their composition, is presented. The research was performed on fabric samples that differ in raw material composition and aramid content. The samples were dyed in raw form (group 1) as well as after pretreatment with alkaline scouring (group 2). Measured limiting oxygen index (LOI) values showed that the selected fabrics meet the properties of inherently fire retardant fabrics. Dyeing was performed with Indanthren® Olive Green HB (manufactured by DyStar) vat dye, in exhaustion process, with a bath ratio of 1:30. The dye concentration was 3%, and sodium-hydrosulphite (Na2S2O4) was used as a reducing agent. The colouristic analyses were performed based on spectrophotometric measurement and results interpretation according to CIELab system. The evaluation of primary tactile properties was performed which show an increase of smoothness and softness after scouring and dyeing. Also, wash fastness as well as light fastness tests have shown satisfactory fastness properties.  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