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   2024篇
  免费   129篇
  国内免费   13篇
电工技术   28篇
综合类   9篇
化学工业   655篇
金属工艺   75篇
机械仪表   27篇
建筑科学   141篇
矿业工程   24篇
能源动力   52篇
轻工业   163篇
水利工程   7篇
石油天然气   12篇
无线电   129篇
一般工业技术   401篇
冶金工业   153篇
原子能技术   8篇
自动化技术   282篇
  2023年   15篇
  2022年   27篇
  2021年   57篇
  2020年   44篇
  2019年   47篇
  2018年   34篇
  2017年   40篇
  2016年   76篇
  2015年   77篇
  2014年   101篇
  2013年   109篇
  2012年   89篇
  2011年   112篇
  2010年   70篇
  2009年   101篇
  2008年   80篇
  2007年   83篇
  2006年   73篇
  2005年   72篇
  2004年   55篇
  2003年   56篇
  2002年   47篇
  2001年   36篇
  2000年   28篇
  1999年   37篇
  1998年   52篇
  1997年   39篇
  1996年   41篇
  1995年   35篇
  1994年   35篇
  1993年   36篇
  1992年   33篇
  1991年   24篇
  1990年   24篇
  1989年   19篇
  1988年   14篇
  1987年   11篇
  1986年   22篇
  1985年   17篇
  1984年   12篇
  1983年   27篇
  1982年   9篇
  1981年   17篇
  1980年   17篇
  1979年   15篇
  1978年   17篇
  1977年   10篇
  1976年   21篇
  1974年   7篇
  1973年   6篇
排序方式: 共有2166条查询结果,搜索用时 15 毫秒
61.
Clinical proteomics is defined as application of proteome analysis aiming at improving the current clinical situation. As such, the success of clinical proteomics should be assessed based on the clinical impact following implementation of the findings. While we have experienced significant technological advancements in mass spectrometry in the last years, based on the above measure, this has not at all resulted in similar advancements in clinical proteomics. Although a large number of proteomic biomarkers have been described, most of them were not subsequently validated, and certainly have had no impact in clinical decision making as yet. Under the current conditions, it appears likely that the situation will not change significantly: we will be flooded by reports on biomarkers, but not see any implementation. In this article, some key issues in proteomic biomarker research are pinpointed, based on the experience with CE‐MS, likely also holding true for biomarkers resulting from other analysis domains.  相似文献   
62.
For the production of high-quality goods in industrial furnaces using minimal expenditure of energy, optimization of the process parameters is required. One tool for improving the processes economically is the simulation of the furnaces by using Computational Fluid Dynamics (CFD). The pre-heating process of a steel strip in a section of an annealing furnace for surface treatment in a hot-dip galvanizing process was simulated using the commercial CFD software Ansys Fluent 15.0. For combustion, the Equilibrium model is used, turbulence is modeled by the realizable-k-ε model, and radiation is taken into account by using the Discrete Ordinate Method (DOM).  相似文献   
63.

The main principle of diagnostic pathology is the reliable interpretation of individual cells in context of the tissue architecture. Especially a confident examination of bone marrow specimen is dependent on a valid classification of myeloid cells. In this work, we propose a novel rotation-invariant learning scheme for multi-class echo state networks (ESNs), which achieves very high performance in automated bone marrow cell classification. Based on representing static images as temporal sequence of rotations, we show how ESNs robustly recognize cells of arbitrary rotations by taking advantage of their short-term memory capacity. The performance of our approach is compared to a classification random forest that learns rotation-invariance in a conventional way by exhaustively training on multiple rotations of individual samples. The methods were evaluated on a human bone marrow image database consisting of granulopoietic and erythropoietic cells in different maturation stages. Our ESN approach to cell classification does not rely on segmentation of cells or manual feature extraction and can therefore directly be applied to image data.

  相似文献   
64.
Successful tissue engineering with the aid of a polymer scaffold offers the possibility to produce a larger construct and to mould the shape after the defect. We investigated the use of cryogelation to form protein-based scaffolds through different types of formation mechanisms; enzymatic crosslinking, chemical crosslinking, and non-covalent interactions. Casein was found to best suited for enzymatic crosslinking, gelatin for chemical crosslinking, and ovalbumin for non-covalent interactions. Fibroblasts and myoblasts were used to evaluate the cryogels for tissue engineering purposes. The stability of the cryogels over time in culture differed depending on formation mechanism. Casein cryogels showed best potential to be used in skeletal tissue engineering, whereas gelatin cryogels would be more suitable for compliable soft tissues even though it also seemed to support a myogenic phenotype. Ovalbumin cryogels would be better suited for elastic tissues with faster regeneration properties due to its faster degradation time. Overall, the cryogelation technique offers a fast, cheap and reproducible way of creating porous scaffolds from proteins without the use of toxic compounds.  相似文献   
65.
66.
During operation, thermomechanical stresses occur in refractory linings. Under elevated stress and temperatures, these ceramics experience primary creep, which can further proceed to the secondary and tertiary creep stages. This necessitates a characterization of their three-stage creep behavior. Hence, two advanced uniaxial tensile and compressive creep testing devices are utilized. The Norton-Bailey creep equations and an inverse identification procedure are applied for the evaluation of the creep curves. To account for the full three-stage creep behavior in thermomechanical modelling activities, a creep-stage transition criterion is identified and subsequently implemented together with the Norton-Bailey creep-strain rate representations in a new developed creep model. The finite element simulation results from different creep testing procedures are in accordance with the corresponding experimental results of a magnesia-chromite refractory ceramic. The study also reveals the temperature-dependent asymmetrical creep behavior of the material in terms of the creep-strain rates and critical creep strains.  相似文献   
67.
68.
SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Ju?lich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 μeV, a dynamic range of ±?31 μeV, and a signal-to-noise ratio of up to 1750:1.  相似文献   
69.
The triterpenoid (+)-ambrein is the major component of ambergris, a coprolite of the sperm whale that can only be rarely found on shores. Upon oxidative degradation of (+)-ambrein, several fragrance molecules are formed, amongst them (−)-ambrox, one of the highest valued compounds in the perfume industry. In order to generate a Saccharomyces cerevisiae whole-cell biocatalyst for the production of (+)-ambrein, intracellular supply of the squalene was enhanced by overexpression of two central enzymes in the mevalonate and sterol biosynthesis pathway, namely the N-terminally truncated 3-hydroxy-3-methylglutaryl-CoA reductase 1 (tHMG) and the squalene synthase (ERG9). In addition, another key enzyme in sterol biosynthesis, squalene epoxidase (ERG1) was inhibited by an experimentally defined amount of the inhibitor terbinafine in order to reduce flux of squalene towards ergosterol biosynthesis while retaining sufficient activity to maintain cell viability and growth. Heterologous expression of a promiscuous variant of Bacillus megaterium tetraprenyl-β-curcumene cyclase (BmeTC-D373C), which has been shown to be able to catalyse the conversion of squalene to 3-deoxyachillol and then further to (+)-ambrein resulted in production of these triterpenoids in S. cerevisiae for the first time. Triterpenoid yields are comparable with the best microbial production chassis described in literature so far, the methylotrophic yeast Pichia pastoris. Consequently, we discuss similarities and differences of these two yeast species when applied for whole-cell (+)-ambrein production.  相似文献   
70.
Food Science and Biotechnology - Histamine intolerance (HIT) is thought to be caused by a disproportionate amount of histamine in the body. The enzyme diamine oxidase (DAO) is considered for the...  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