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   174篇
  免费   1篇
  国内免费   1篇
电工技术   9篇
化学工业   21篇
金属工艺   2篇
建筑科学   3篇
能源动力   3篇
轻工业   9篇
水利工程   3篇
无线电   23篇
一般工业技术   29篇
冶金工业   36篇
原子能技术   2篇
自动化技术   36篇
  2023年   2篇
  2022年   8篇
  2021年   7篇
  2019年   2篇
  2017年   1篇
  2016年   3篇
  2015年   3篇
  2014年   11篇
  2013年   16篇
  2012年   4篇
  2011年   7篇
  2010年   3篇
  2009年   8篇
  2008年   8篇
  2007年   11篇
  2006年   12篇
  2005年   4篇
  2004年   3篇
  2003年   1篇
  2002年   2篇
  2001年   1篇
  2000年   5篇
  1999年   7篇
  1998年   9篇
  1997年   7篇
  1996年   5篇
  1995年   5篇
  1994年   2篇
  1993年   2篇
  1992年   2篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1985年   1篇
  1984年   1篇
  1983年   3篇
  1977年   1篇
  1976年   2篇
  1967年   1篇
  1955年   1篇
排序方式: 共有176条查询结果,搜索用时 15 毫秒
81.
The structural investigations performed on Guarini’s Chapel of the Holy Shroud in Torino have made it possible to come closer than ever before to understanding its structural behaviour. They have also shed light on the building’s history. This paper presents some of the new findings about key elements of the structure, and mentions some of the still open questions.  相似文献   
82.
We present high-resolution resistivity and magnetoresistivity measurements on a DyNi2B2C thin film obtained by laser ablation. The measurements are interpreted in the framework of the theory developed by Yamada and Takada (YT) in the early 1970s (Yamada H., Takada S. Prog Theor Phys 1973;49:1401) for the magnetoresistivity of the antiferromagnetic materials and permit identification of the magnetic field Hc2 that destroys the magnetic ordering. So, we obtain a H–T phase diagram where the antiferromagnetic and paramagnetic states are unambiguously determined and that we compare with data in the literature. Finally, in the paramagnetic state we have found a linear dependence between magnetoresistivity and the square of the magnetization.  相似文献   
83.
A compact circuit model for power PiN diode is presented in this paper. The model includes thermal and electrical characteristics. Emitter efficiency effect, voltage drop due to epilayer region and accurate modeling of reverse recovery and forward recovery are main features of the electric part of the model. The thermal part of the model dynamically takes into account heat generation and flow through the device and includes the effect of temperature on diode model parameters. Circuit implementation of device thermal equations includes the effect of the non uniform heat generation in the chip and, hence, is very effective in modeling thermal response to short current pulses, which give a substantial modification of power rectifiers characteristics with negligible case heating. Modeling of charge distribution in the epilayer and of heat flow, is achieved through an approximation of the Laplace transform of the exact solution. The model is implemented as a Pspice subcircuit. Medici device simulations, including self heating, are used to validate the Pspice model.  相似文献   
84.
Amyotrophic lateral sclerosis (ALS) is a disease with a resilient neuroinflammatory component caused by activated microglia and infiltrated immune cells. How to successfully balance neuroprotective versus neurotoxic actions through the use of anti-inflammatory agents is still under debate. There has been a boost of awareness regarding the role of extracellular ATP and purinergic receptors in modulating the physiological and pathological mechanisms in the nervous system. Particularly in ALS, it is known that the purinergic ionotropic P2X7 receptor plays a dual role in disease progression by acting at different cellular and molecular levels. In this context, we previously demonstrated that the P2X7 receptor antagonist, brilliant blue G, reduces neuroinflammation and ameliorates some of the pathological features of ALS in the SOD1-G93A mouse model. Here, we test the novel, noncommercially available, and centrally permeant Axxam proprietary P2X7 antagonist, AXX71, in SOD1-G93A mice, by assessing some behavioral and molecular parameters, among which are disease progression, survival, gliosis, and motor neuron wealth. We demonstrate that AXX71 affects the early symptomatic phase of the disease by reducing microglia-related proinflammatory markers and autophagy without affecting the anti-inflammatory markers or motor neuron survival. Our results suggest that P2X7 modulation can be further investigated as a therapeutic strategy in preclinical studies, and exploited in ALS clinical trials.  相似文献   
85.
Data Mining and Knowledge Discovery - Pattern mining is well established in data mining research, especially for mining binary datasets. Surprisingly, there is much less work about numerical...  相似文献   
86.
A new approach to design the phase to sine mapper of a direct digital frequency synthesizer (DDFS) is presented. The proposed technique uses an optimized polynomial expansion of sine and cosine functions to achieve either a 60-dBc spurious free dynamic range (SFDR), with a second-order polynomial, or a 80-dBc SFDR, with third-order polynomials. Polynomial computation is done by using new canonical-signed-digit (CSD) hyperfolding technique. This approach exploits all the symmetries of polynomials parallel computation and uses CSD encoding to minimize hardware complexity. CSD hyperfolding technique is also presented in the paper. The performances of new DDFS compares favorably with circuits designed using state-of-the-art Cordic algorithm technique.  相似文献   
87.
In this paper the authors describes a rare case of renal hydatidosis complicated by post acute pancreatitic cyst. There have been no reports up till now either of any physiopathological between the development of hydatid cysts in the vicinity of the pancreas and subsequent pancreatitis, or of any correlation between long-term albendazole therapy and acute pancreatitis. In our particular case, however, the volumetric increase of the renal cyst caused external compression of the pancreas and the consequent slowing-down of bilio-pancreatic flow, which probably led to the development of acute pancreatitis. Since, in our opinion, the pancreatic pseudocyst required surgical removal, we decided to perform the operation there and then; intraoperative examination of the cystic fluid and the presence of daughter cysts confirmed the suspected diagnosis of hydatidosis, of clear renal origin since it was closely attached to the upper pole and continued along the upper calyces renales; the cyst was easily detached from the lower and posterior edge of the liver, and was completely removed, together with its pericystium, which was detached from the lower surface of the liver and from the inferior subhepatic vein; only a tiny disk of pericystium was left in communication with a calyx, sutured to the rest of the kidney. The pancreatic cyst was drained by means of a mesocolic Roux-loop cysto-jejunostomy.  相似文献   
88.
Transforming growth factor beta1 (TGF-beta1) is a potent modulator of cell proliferation in vitro, and recent studies have demonstrated its overexpression in several different tumours; nevertheless, the molecular mechanisms of TGF-beta1 action on cell growth and differentiation have not been fully elucidated. To clarify the role of TGF-beta and its receptor in human endometrial proliferation and differentiation, TGF-beta1 expression at both the mRNA and protein levels has been evaluated by using Northern blotting and immunohistochemistry, in both normal (atrophic, proliferative and secretory) and neoplastic (adenocarcinoma) endometrial samples. This study demonstrates that TGF-beta1 mRNA expression is dramatically reduced in endometrial carcinomas with respect to non-neoplastic tissues, whereas the immunohistochemical expression of TGF-beta1 is enhanced in the epithelial component of endometrial carcinomas compared with non-neoplastic tissues. These data suggest that TGF-beta1 acts as a paracrine regulator of endometrial cell proliferation and that it may contribute to the carcinogenic mechanisms of endometrial carcinoma.  相似文献   
89.
A comprehensive particle size distribution model has been developed for the simulation of γ′ precipitation in multicomponent Ni alloys. Nucleation, growth and coarsening of the precipitates are described by a particle size distribution. The growth rate of each precipitate class is calculated with a multi-component diffusion model formulated for non-diagonal matrices of diffusion coefficients. The model is fully coupled with CALPHAD calculations of the thermodynamic equilibrium at the interface, including a direct treatment of the effect of curvature through modification of the Gibbs free energy. An optimization strategy was developed to minimize the computational cost. The model was used to simulate ageing heat treatment at 600 °C of Ni–7.56 at.% Al–8.56 at.% Cr, which was studied experimentally by Booth-Morrison and others (Booth-Morrison C, Weninger J, Sudbrack CK, Mao Z, Noebe RD, Seidman DN. Acta Mater 2008;56:3422; Mao Z, Booth-Morrison C, Sudbrack CK, Martin G, Seidman DN. Acta Mater 2012;60:1871). The comparisons showed that the precipitation stages of γ′ precipitates are correctly captured by the numerical model. It was shown that non-diagonal diffusion coefficients substantially influence the selection of the operating tie-line and the overall transformation kinetics. With non-diagonal diffusion matrices, complex phenomena such as uphill diffusion of Cr due to the Al gradients were evidenced and explained.  相似文献   
90.
Dyslipidemias can affect molecular networks underlying the metabolic homeostasis and vascular function leading to atherogenesis at early stages of development. Since disease-related proteins often interact with each other in functional modules, many advanced network-oriented algorithms were applied to patient-derived big data to identify the complex gene–environment interactions underlying the early pathophysiology of dyslipidemias and atherosclerosis. Both the proprotein convertase subtilisin/kexin type 7 (PCSK7) and collagen type 1 alpha 1 chain (COL1A1) genes arose from the application of TFfit and WGCNA algorithms, respectively, as potential useful therapeutic targets in prevention of dyslipidemias. Moreover, the Seed Connector algorithm (SCA) algorithm suggested a putative role of the neuropilin-1 (NRP1) protein as drug target, whereas a regression network analysis reported that niacin may provide benefits in mixed dyslipidemias. Dyslipidemias are highly heterogeneous at the clinical level; thus, it would be helpful to overcome traditional evidence-based paradigm toward a personalized risk assessment and therapy. Network Medicine uses omics data, artificial intelligence (AI), imaging tools, and clinical information to design personalized therapy of dyslipidemias and atherosclerosis. Recently, a novel non-invasive AI-derived biomarker, named Fat Attenuation Index (FAI™) has been established to early detect clinical signs of atherosclerosis. Moreover, an integrated AI-radiomics approach can detect fibrosis and microvascular remodeling improving the customized risk assessment. Here, we offer a network-based roadmap ranging from novel molecular pathways to digital therapeutics which can improve personalized therapy of dyslipidemias.  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