全文获取类型
收费全文 | 985篇 |
免费 | 50篇 |
专业分类
电工技术 | 5篇 |
综合类 | 3篇 |
化学工业 | 331篇 |
金属工艺 | 26篇 |
机械仪表 | 7篇 |
建筑科学 | 39篇 |
能源动力 | 23篇 |
轻工业 | 109篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 26篇 |
一般工业技术 | 157篇 |
冶金工业 | 167篇 |
原子能技术 | 7篇 |
自动化技术 | 125篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 24篇 |
2020年 | 7篇 |
2019年 | 26篇 |
2018年 | 32篇 |
2017年 | 22篇 |
2016年 | 17篇 |
2015年 | 24篇 |
2014年 | 36篇 |
2013年 | 68篇 |
2012年 | 51篇 |
2011年 | 59篇 |
2010年 | 50篇 |
2009年 | 47篇 |
2008年 | 41篇 |
2007年 | 42篇 |
2006年 | 24篇 |
2005年 | 16篇 |
2004年 | 27篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 20篇 |
2000年 | 5篇 |
1999年 | 17篇 |
1998年 | 47篇 |
1997年 | 31篇 |
1996年 | 40篇 |
1995年 | 17篇 |
1994年 | 10篇 |
1993年 | 21篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1975年 | 4篇 |
1973年 | 4篇 |
1969年 | 4篇 |
排序方式: 共有1035条查询结果,搜索用时 15 毫秒
81.
82.
HB Benestad T S?rensen KM Iranpour K Liest?l K Yogesan I Str?m-Gundersen X Wang D L?vhaug 《Canadian Metallurgical Quarterly》1998,26(10):936-941
A system for automatic analysis of in vitro hematopoietic colonies is described and evaluated. With the standard resolution provided by video cameras, the improvement in visualization obtained using features other than size and darkness when classifying potential colonies appears to be limited. We confirmed this by comparing results obtained with the test system with those obtained with a commercial one. However, for some applications it may be useful to supplement the system with specific methods, e.g., to separate merged colonies. Digital image analyses provide new possibilities, for instance of measuring the total cellularity of the dish or analyzing colonies according to the size and cell density of each colony. Examples provided are time course studies of colony development, cellularity feedback effects on colony sizes, and bell-shaped dose-response curves for the growth stimulation obtained by certain conditioned media on a subpopulation of progenitor cells that gives rise to large colonies. 相似文献
83.
84.
85.
Structure–Activity Relationship Study of Spider Polyamine Toxins as Inhibitors of Ionotropic Glutamate Receptors
下载免费PDF全文
![点击此处可从《ChemMedChem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Xiao‐Feng Xiong Dr. Mette H. Poulsen Rama A. Hussein Dr. Niels G. Nørager Prof. Kristian Strømgaard 《ChemMedChem》2014,9(12):2661-2670
The spider polyamine toxins Joro spider toxin‐3 (JSTX‐3) and Nephila polyamine toxins‐1 and ‐8 (NPTX‐1 and NPTX‐8) are isolated from the venom of the orb‐weaver spider Nephila clavata (Joro spider). They share a high degree of structural resemblance, their aromatic head groups being the only difference, and were recently found to be very potent open‐channel blockers of ionotropic glutamate (iGlu) receptors. In this study we designed and synthesized a collection of 24 analogues of these toxins using a recently developed solid‐phase synthetic methodology. Systematic variation in two regions of the toxins and subsequent evaluation of biological activity at AMPA and NMDA subtypes of iGlu receptors provided succinct information on structure–activity relationships. In particular, one set of analogues were found to display exquisite selectivity and potency for AMPA receptors relative to the natural products. Thus, this systematic SAR study has provided new pharmacological tools for studies of iGlu receptors. 相似文献
86.
On the case of a parallel metrological measurement of unattached and attached concentrations of radon progeny, the evaluation by an inversion of the Jacobi-Porstend?rfer room model indicates a real overestimation of the concentration of RaA ((218)Po). 相似文献
87.
M. Guzik J. Cybińska E. Tomaszewicz Y. Guyot J. Legendziewicz G. Boulon W. Str?k 《Optical Materials》2011,34(2):487-495
In the framework of systematic investigations of the optical properties of a new tungstate ZnY4W3O16 in which Y3+ cations allow for rare-earth ions doping, the compounds doped with neodymium Nd3+ ion were synthesized, analyzed and considered as a possible laser material. The crystalline stoichiometric sample of the chemical formula ZnNd4W3O16 and their yttrium diluted analogues 0.5, 1, 5 and 10 mol% Nd3+-doped ZnY4W3O16 were obtained by a solid-state reaction. X-ray powder diffraction analysis as well as the IR spectra were used to the structural characterization of the compounds. Electron microscopy has been used to analyze the grain size, the presence of aggregates, and the type of boundary between the microcrystals. In order to study spectroscopic properties, the high resolution absorption and emission spectra at room and low temperature were measured in visible and IR regions. The radiative transition probabilities in those tungstates were calculated and analyzed. Based on the 4 K absorption spectra in the range of 4I9/2 → 2P1/2 transition the number of metal sites occupied by the dopants was determined. The strong fluorescent emission involving the 4F3/2 → 4I9/2, 4I11/2, 4I13/2 transitions at 298 and 77 K were observed under pulsed laser and xenon lamp excitation. The dynamics of the Nd3+ excited states were characterized by decay times measurements and compared to earlier reported data for neodymium tungstates. 相似文献
88.
Klánová J Diamond M Jones K Lammel G Lohmann R Pirrone N Scheringer M Balducci C Bidleman T Bláha K Bláha L Booij K Bouwman H Breivik K Eckhardt S Fiedler H Garrigues P Harner T Holoubek I Hung H MacLeod M Magulova K Mosca S Pistocchi A Simonich S Smedes F Stephanou E Sweetman A Sebková K Venier M Vighi M Vrana B Wania F Weber R Weiss P 《Environmental science & technology》2011,45(18):7617-7619
89.
Life cycle environmental assessment of lithium-ion and nickel metal hydride batteries for plug-in hybrid and battery electric vehicles 总被引:1,自引:0,他引:1
This study presents the life cycle assessment (LCA) of three batteries for plug-in hybrid and full performance battery electric vehicles. A transparent life cycle inventory (LCI) was compiled in a component-wise manner for nickel metal hydride (NiMH), nickel cobalt manganese lithium-ion (NCM), and iron phosphate lithium-ion (LFP) batteries. The battery systems were investigated with a functional unit based on energy storage, and environmental impacts were analyzed using midpoint indicators. On a per-storage basis, the NiMH technology was found to have the highest environmental impact, followed by NCM and then LFP, for all categories considered except ozone depletion potential. We found higher life cycle global warming emissions than have been previously reported. Detailed contribution and structural path analyses allowed for the identification of the different processes and value-chains most directly responsible for these emissions. This article contributes a public and detailed inventory, which can be easily be adapted to any powertrain, along with readily usable environmental performance assessments. 相似文献
90.
Strohalm M Strohalm J Kaftan F Krásný L Volný M Novák P Ulbrich K Havlíček V 《Analytical chemistry》2011,83(13):5458-5462
Traditional tissue-sectioning techniques for histological samples utilize various embedding media to stabilize the tissue on a sectioning target and to provide a smooth cutting surface. Due to the ion suppression effect in MALDI ionization and number of background peaks in the low-mass region, these media are not suitable for mass spectrometry imaging (MSI) experiments. To overcome this, droplets of water are often used to mount the tissue on a sectioning target, but the ice block formed around the tissue does not provide a good support for sectioning of fragile samples. In this work, we propose a novel embedding media, compatible with MALDI ionization and MSI experiments, based on poly[N-(2-hydroxypropyl)methacrylamide] (pHPMA). Using a reversible addition-fragmentation chain transfer polymerization technique, well-defined pHPMA polymer with narrow mass distribution was prepared. Benefits of the resulted pHPMA-based embedding media were tested on different tissue samples. 相似文献