全文获取类型
收费全文 | 791篇 |
免费 | 18篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 62篇 |
化学工业 | 96篇 |
金属工艺 | 32篇 |
机械仪表 | 22篇 |
建筑科学 | 14篇 |
能源动力 | 12篇 |
轻工业 | 70篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 51篇 |
一般工业技术 | 128篇 |
冶金工业 | 256篇 |
原子能技术 | 31篇 |
自动化技术 | 41篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 17篇 |
2013年 | 40篇 |
2012年 | 31篇 |
2011年 | 41篇 |
2010年 | 17篇 |
2009年 | 27篇 |
2008年 | 19篇 |
2007年 | 28篇 |
2006年 | 18篇 |
2005年 | 26篇 |
2004年 | 9篇 |
2003年 | 20篇 |
2002年 | 18篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 30篇 |
1998年 | 91篇 |
1997年 | 52篇 |
1996年 | 37篇 |
1995年 | 25篇 |
1994年 | 15篇 |
1993年 | 21篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 17篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 10篇 |
1973年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有817条查询结果,搜索用时 428 毫秒
101.
Inasmuch as precise correlations of light- and electronmicroscopy are crucial for understanding biostructure, it seemed necessary to bring together the advantages of the glyoxylic acid (GA) method (for inducing monoamine fluorescence) and electron microscopy. A combined fluorescence and electron microscope method using GA is introduced. The brain is perfused by 2% GA in Krebs-Ringer bicarbonate buffer (pH 7.0) and this solution is followed by 4% paraformaldehyde containing 0.5% glutaraldehyde in Sorensen's phosphate buffer (pH 7.4). Sections are cut by cryostat or by vitratome and incubated in 2% GA in phosphate buffer (pH 7.0). Using fluorescence microscopy, features of interest are sketched and/or photographed. Afterwards, the same or subsequent section is processed for electron microscopy. Since axons of catecholamine-containing neurons (as well as their perikarya and terminals) are visualized by GA, the recommended procedure expands the range of studies concerning monoamine neurons that can now be carried out effectively. 相似文献
102.
103.
104.
Endocrine glands of the ironfish were studied light microscopically to elucidate the relationship between the races of the genus Carassius. The rostral pars distalis of the adenohypophysis consists mainly of acidophils corresponding to prolactin cells and lead-hematoxylin positive cells corresponding to corticotrophs (ACTH cells). The prolactin cells are obviously arranged in the form of follicles. The proximal pars distalis contains orangenophils (STH cells) and two types of basophils (TSH and GTH cells). In the pars intermedia, three types of cells are identified: periodic acid Schiff positive cells, lead-hematoxylin stainable cells and orangenophils containing PAS positive coarse granules. In addition, small agranular cells are seldom demonstrated in the entire adenohypophysis. A considerable amount of aldehyde fuchsin positive neurosecretory material is laden in the cells of the nucleus preopticus and in the pars nervosa. The nucleus lateralis tuberis is composed of three portions: pars anterior, pars posterior, and pars lateralis. The thyroid follicles found in the pharyngeal region and head kidney show a mild state of activity. The interrenal cells intermingled with the chromaffin cells have a considerable amount of eosinophil cytoplasm. Judging from the gonadal condition, the breeding season of the ironfish may extend to the end of July. 相似文献
105.
S Chiba 《Canadian Metallurgical Quarterly》1976,119(1):101-102
The effects of potassium chloride on inotropic and chronotropic activity were investigated in five isolated canine atrium preparations which were suspended in a bath and perfused with arterial blood from the carotid artery of the heparinized support dog. Potassium chloride administered into the cannulated sinus node artery in a dose range of 100 mug-1 mg produced a dose-related negative inotropic and a positive chronotropic effect. These effects were not influenced by treatment with either atropine or propranolol. From these results, it is concluded that potassium had a direct negative effect on atrial contractility and a direct positive effect on atrial rate. 相似文献
106.
We developed an interdigitated array electrode (IDAE) consisting of a metal oxide electrode and a metal band heteroelectrode and employed it for the selective detection of catecholamines. We used an indium-tin oxide (ITO) film as the oxidation electrode of the IDAE because the ITO was able to suppress response currents from L-ascorbic acid (AA) and uric acid (UA), which are major electroactive interferents in biological fluids. However, the ITO film also suppresses the reduction of quinones including oxidized catecholamines. We developed a simple technique for fabricating our hetero IDAE, which also preserves the electrochemical properties of the ITO. When we compared hetero ITO-gold, homo ITO-ITO, and carbon-carbon IDAEs, we found that the hetero IDAE provided both high sensitivity and selectivity for DA detection. We achieved high selectivities for DA against AA and UA. The ratios of the response currents of AA and UA to DA were calculated as 6 and 5%, respectively. 相似文献
107.
Quantitative detection system for maize sample containing combined-trait genetically modified maize 总被引:4,自引:0,他引:4
Akiyama H Watanabe T Wakabayashi K Nakade S Yasui S Sakata K Chiba R Spiegelhalter F Hino A Maitani T 《Analytical chemistry》2005,77(22):7421-7428
Various countries have established regulations that stipulate the labeling of agricultural commodities, feed, and food products that contain or are made from genetically modified (GM) material or that contain adventitious GM material in amounts that exceed certain threshold levels. While regulations in some countries refer to GM material on a weight per weight (w/w) percentage, the currently applied detection methods do not directly measure the w/w percentage of the GM material. Depending on the particular method and the sample matrix it is applied to, the conversion of analytical results to a w/w percentage is challenging or not possible. The first rapid PCR system for GM maize detection on a single kernel basis has been developed. The equipment for the grinding of individual kernels and a silica membrane-based 96-well DNA extraction kit were both significantly revised and optimized for this particular purpose, respectively. We developed a multiplex real-time PCR method for the rapid quantification of GM DNA sequences in the obtained DNA solutions. In addition, a multiplex qualitative PCR detection method allows for the simultaneous detection of different GM maize traits in each kernel and thereby for identification of individual kernels that contain a combination of two or more GM traits. Especially for grain samples that potentially contain combined-trait GM maize kernels, the proposed methods can deliver informative results in a rapid, precise, and reliable manner. 相似文献
108.
Microstructures and bond strengths of plasma-sprayed hydroxyapatite coatings on porous titanium substrates 总被引:3,自引:0,他引:3
Oh IH Nomura N Chiba A Murayama Y Masahashi N Lee BT Hanada S 《Journal of materials science. Materials in medicine》2005,16(7):635-640
Hydroxyapatite (HA) coating was carried out by plasma spraying on bulk Ti substrates and porous Ti substrates having a Young’s modulus similar to that of human bone. The microstructures and bond strengths of HA coatings were investigated in this study. The HA coatings with thickness of 200–250 μ m were free from cracks at interfaces between the coating and Ti substrates. XRD analysis revealed that the HA powder used for plasma spraying had a highly crystallized apatite structure, while the HA coating contained several phases other than HA. The bond strength between the HA coating and the Ti substrates evaluated by standard bonding test (ASTM C633-01) were strongly affected by the failure behavior of the HA coating. A mechanism to explain the failure is discussed in terms of surface roughness of the plasma-sprayed HA coatings on the bulk and porous Ti substrates. 相似文献
109.
110.