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   1425篇
  免费   47篇
  国内免费   4篇
电工技术   25篇
综合类   1篇
化学工业   409篇
金属工艺   16篇
机械仪表   25篇
建筑科学   33篇
矿业工程   7篇
能源动力   22篇
轻工业   67篇
水利工程   10篇
石油天然气   1篇
武器工业   1篇
无线电   105篇
一般工业技术   252篇
冶金工业   238篇
原子能技术   11篇
自动化技术   253篇
  2023年   11篇
  2022年   38篇
  2021年   29篇
  2020年   17篇
  2019年   18篇
  2018年   23篇
  2017年   24篇
  2016年   26篇
  2015年   19篇
  2014年   34篇
  2013年   100篇
  2012年   61篇
  2011年   70篇
  2010年   46篇
  2009年   50篇
  2008年   33篇
  2007年   30篇
  2006年   55篇
  2005年   47篇
  2004年   51篇
  2003年   49篇
  2002年   35篇
  2001年   17篇
  2000年   22篇
  1999年   16篇
  1998年   18篇
  1997年   20篇
  1996年   24篇
  1995年   16篇
  1994年   20篇
  1993年   16篇
  1992年   24篇
  1991年   11篇
  1990年   14篇
  1989年   19篇
  1988年   20篇
  1987年   12篇
  1986年   17篇
  1985年   15篇
  1982年   19篇
  1981年   13篇
  1980年   14篇
  1979年   16篇
  1978年   23篇
  1977年   16篇
  1976年   25篇
  1975年   16篇
  1974年   21篇
  1973年   14篇
  1970年   10篇
排序方式: 共有1476条查询结果,搜索用时 0 毫秒
141.
Approximately zero-order release of ephedrine hydrochloride and procaine hydrochloride was obtained from multiple-layered matrixes of hydrogenated castor oil containing various concentrations of the medicinal compound in each layer. For the examples presented, an apparent zero-order release was observed for the release of 50-90% of the medicinal compound.  相似文献   
142.
143.
We propose method for the local spectral analysis of images via the two-dimensional continuous wavelet transform with the Morlet wavelet based on its representation as a solution of the partial differential equation. It has been shown that a transformed function uniquely determines an initial value for the equation, i.e. a Cauchy problem is stated. Its solving implies that scale parameter a plays a role of “time variable” and two translation parameters b x , b y are spatial independent variables. Numerical examples are given to illustrate the efficiency of the proposed method.  相似文献   
144.
Dielectric, X-ray, and piezoelectric studies of highly-resistive Li-doped (1-x)PbFe(1/2)Nb(1/2)O(3)-(x)PbTiO(3) (PFN-xPT) ceramics from the 0 ≤ x ≤ 0.2 range fabricated by solid-state synthesis and usual sintering have been carried out. Distinct anomalies of dielectric and piezoelectric parameters, corresponding to the transition between rhombohedral (monoclinic) and tetragonal ferroelectric phases, have been observed in pure PFN and PFN-xPT compositions with PbTiO(3) content up to 8 mol.%. The x,T-phase diagram of the PFN-xPT solid solution system has been constructed using these data.  相似文献   
145.
Red blood cell (RBC) aggregation and deformation are governed by the molecular processes occurring on the membrane. Since several social important diseases are accompanied by alterations in RBC aggregation and deformability, it is important to develop a diagnostic parameter of RBC membrane structural integrity and stability. In this work, we propose membrane microviscosity assessed by time-resolved fluorescence anisotropy of the lipophilic PKH26 fluorescent probe as a diagnostic parameter. We measured the fluorescence decay curves of the PKH26 probe in the RBC membrane to establish the optimal parameters of the developed fluorescence assay. We observed a complex biphasic profile of the fluorescence anisotropy decay characterized by two correlation times corresponding to the rotational diffusion of free PKH26, and membrane-bounded molecules of the probe. The developed assay allowed us to estimate membrane microviscosity ηm in the range of 100–500 cP depending on the temperature, which paves the way for assessing RBC membrane properties in clinical applications as predictors of blood microrheological abnormalities.  相似文献   
146.
Tumor necrosis factor (TNF) inhibitors (anti-TNFs) represent a cornerstone of the treatment of various immune-mediated inflammatory diseases and are among the most commercially successful therapeutic agents. Knowledge of TNF binding partners is critical for identification of the factors able to affect clinical efficacy of the anti-TNFs. Here, we report that among eighteen representatives of the multifunctional S100 protein family, only S100A11, S100A12 and S100A13 interact with the soluble form of TNF (sTNF) in vitro. The lowest equilibrium dissociation constants (Kd) for the complexes with monomeric sTNF determined using surface plasmon resonance spectroscopy range from 2 nM to 28 nM. The apparent Kd values for the complexes of multimeric sTNF with S100A11/A12 estimated from fluorimetric titrations are 0.1–0.3 µM. S100A12/A13 suppress the cytotoxic activity of sTNF against Huh-7 cells, as evidenced by the MTT assay. Structural modeling indicates that the sTNF-S100 interactions may interfere with the sTNF recognition by the therapeutic anti-TNFs. Bioinformatics analysis reveals dysregulation of TNF and S100A11/A12/A13 in numerous disorders. Overall, we have shown a novel potential regulatory role of the extracellular forms of specific S100 proteins that may affect the efficacy of anti-TNF treatment in various diseases.  相似文献   
147.
A stationary mold-ingot bottom withdrawal ac consumable electrode electroslag furnace with electrode change capability has been installed for melting superalloys at Teledyne-Allvac. The furnace, which utilizes melt voltage and rms current regulation for automatic melt control and its operation are described. The stationary mold-ingot bottom withdrawal and auto-melt control concepts have proven successful and solution hardening superalloys are in routine production with high quality and good yield. Additionally, experimental melting of the nickel base and iron base precipitation hardening superalloys (containing titanium and aluminum) is in process, and initial results look encouraging with respect to quality and chemistry control.  相似文献   
148.
In a free-living flatworm, Macrostomum lignano, an S-phase kinase-associated protein 1 (SKP1) homologous gene was identified as enriched in proliferating cells, suggesting that it can function in the regulation of stem cells or germline cells since these are the only two types of proliferating cells in flatworms. SKP1 is a conserved protein that plays a role in ubiquitination processes as a part of the Skp1-Cullin 1-F-box (SCF) ubiquitin ligase complex. However, the exact role of Mlig-SKP1 in M. lignano was not established. Here, we demonstrate that Mlig-SKP1 is neither involved in stem cell regulation during homeostasis, nor in regeneration, but is required for spermatogenesis. Mlig-SKP1(RNAi) animals have increased testes size and decreased fertility as a result of the aberrant maturation of sperm cells. Our findings reinforce the role of ubiquitination pathways in germ cell regulation and demonstrate the conserved role of SKP1 in spermatogenesis.  相似文献   
149.
Mental disorders represent common brain diseases characterized by substantial impairments of social and cognitive functions. The neurobiological causes and mechanisms of psychopathologies still have not been definitively determined. Various forms of brain proteinopathies, which include a disruption of protein conformations and the formation of protein aggregates in brain tissues, may be a possible cause behind the development of psychiatric disorders. Proteinopathies are known to be the main cause of neurodegeneration, but much less attention is given to the role of protein impairments in psychiatric disorders’ pathogenesis, such as depression and schizophrenia. For this reason, the aim of this review was to discuss the potential contribution of protein illnesses in the development of psychopathologies. The first part of the review describes the possible mechanisms of disruption to protein folding and aggregation in the cell: endoplasmic reticulum stress, dysfunction of chaperone proteins, altered mitochondrial function, and impaired autophagy processes. The second part of the review addresses the known proteins whose aggregation in brain tissue has been observed in psychiatric disorders (amyloid, tau protein, α-synuclein, DISC-1, disbindin-1, CRMP1, SNAP25, TRIOBP, NPAS3, GluA1, FABP, and ankyrin-G).  相似文献   
150.
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