全文获取类型
收费全文 | 401篇 |
免费 | 11篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 81篇 |
金属工艺 | 10篇 |
机械仪表 | 6篇 |
建筑科学 | 30篇 |
能源动力 | 17篇 |
轻工业 | 38篇 |
水利工程 | 4篇 |
无线电 | 14篇 |
一般工业技术 | 90篇 |
冶金工业 | 70篇 |
原子能技术 | 10篇 |
自动化技术 | 41篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 27篇 |
2012年 | 13篇 |
2011年 | 26篇 |
2010年 | 18篇 |
2009年 | 20篇 |
2008年 | 9篇 |
2007年 | 22篇 |
2006年 | 18篇 |
2005年 | 11篇 |
2004年 | 15篇 |
2003年 | 8篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 16篇 |
1997年 | 13篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 7篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1969年 | 2篇 |
1964年 | 2篇 |
1963年 | 2篇 |
1961年 | 1篇 |
排序方式: 共有412条查询结果,搜索用时 15 毫秒
1.
T Garnier 《Canadian Metallurgical Quarterly》1996,56(3):297-302
According to some ultrastructural studies, the pericapillary axon terminals in the central nervous system (CNS) are functionally connected with the capillary vessel wall. Thus, it may be expected that the population of pericapillary axon terminals will be morphologically distinct from the terminals at a further distance from the capillary walls. To test this hypothesis, morphometrical analysis of 3,048 axon terminals was performed, comparing terminals situated in the close vicinity of the capillary vessel with those at a distance from the vessels in the lateral, basal, medial, central and cortical nuclei of the amygdaloid body of eight cats. The cross-sectional area and circumference of each identified axon terminal profile were measured, and the shape of synaptic vesicles and the presence of synaptic contacts and granular vesicles were recorded. The statistical evaluation of results was performed by means of the Newman-Keuls' test, Wilcoxon's test, Fisher's contingency-table test and the test for two coefficients of structure. The morphometric examination revealed two ultrastructurally distinct groups of axon terminals, pericapillary and distant terminals, in all the nuclei of the amygdaloid body. The differentiating features were the shape of the synaptic vesicles, the number of synaptic contacts, and the size of the axon terminals. These results further support the hypothesis of a functional connection between axon terminals and the capillary vessel wall in the CNS. 相似文献
2.
3.
4.
5.
BACKGROUND: Recently, investigators have reported the use of endoscopic myotomy in the treatment of esophageal achalasia. As with the open operation, considerable disagreement exists regarding the appropriate length of the myotomy and the need for a concomitant antireflux procedure. METHODS: Patients presenting with symptomatic achalasia between 1993 and 1997 were included in this prospective study. Preoperative studies included barium upper gastrointestinal study, endoscopy, and esophageal manometry. Laparoscopic myotomy was completed in all 20 patients; 18 had concomitant Toupet fundoplication. RESULTS: Operative times ranged from 95 to 345 minutes (mean 216). Blood loss ranged from 50 to 300 cc (mean 100 cc). There were 7 minor complications (5 mucosal injuries repaired laparoscopically, 1 bile leak and 1 splenic capsular tear). Nine patients began a liquid diet on the first day postoperatively; 19 were tolerating liquids by postoperative day 3. Hospital stay ranged from 2 to 20 days (mean 5). Eighteen patients had complete relief of dysphagia, with less than one reflux episode per month. One individual continues to have mild persistent solid food dysphagia. Another patient initially did well but subsequently developed mild recurrent dysphagia and reflux. One patient required laparoscopic take-down of the wrap because of recurrent dysphagia and now has no problems swallowing, but does complain of mild reflux. Two other patients also have mild reflux, 1 of whom did not undergo fundoplication. CONCLUSIONS: Laparoscopic Heller myotomy can be performed safely with excellent results in patients with achalasia. Adding a partial fundoplication appears to help control postoperative symptoms of reflux. This procedure should be considered the procedure of choice in patients with symptomatic esophageal achalasia. 相似文献
6.
Discusses problems involved in collecting data based on observation of small groups. The example of a study of manifestations of cooperation in groups of preschoolers (aged 21–57 mo) is used for illustration. Statistical treatment of observation data and global analysis of data are considered. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
8.
The protein structure code: what is its present status? 总被引:3,自引:0,他引:3
Current methods of prediction of protein conformation are reviewed and the algorithms on which they rely are presented. For non-homologous proteins and after cross-validation the reported methods exhibit a probability index, i.e. the per cent of correctly predicted residues per predicted residues, of 63-65% with a standard deviation of the order of 7% for three conformational states--helix, beta-strand and coil. This present limitation in the accuracy of predictions that use only the information of the local sequence can be related essentially to the effect of long-range interactions specific for each protein family. The methods based on sequence similarity can improve the accuracy of prediction by expressing explicitly the homology of the protein to be predicted with proteins in the database. In these circumstances the probability index can reach 87% with a standard deviation of 6.6%. This property can be used for modeling homologous proteins by aiding in amino acid sequence alignments. The prediction of the tertiary structure of a protein is still limited to the case of modeling a structure based on the known three-dimensional structure of a homologous protein. 相似文献
9.
H.‐G. Boyen G. Kstle K. Zürn T. Herzog F. Weigl P. Ziemann O. Mayer C. Jerome M. Mller J.P. Spatz M.G. Garnier P. Oelhafen 《Advanced functional materials》2003,13(5):359-364
Starting with Co‐salt‐loaded inverse micelles, which form if the diblock copolymer polystyrene‐block‐poly(2‐vinylpyridine) is dissolved in a selective solvent like toluene and CoCl2 is added to the solution, monomicellar arrays of such micelles exhibiting a significant hexagonal order can be prepared on top of various substrates with tailored intermicellar distances and structure heights. In order to remove the polymer matrix and to finally obtain arrays of pure Co nanoparticles, the micelles are first exposed to an oxygen plasma, followed by a treatment in a hydrogen plasma. Applying in‐situ X‐ray photoelectron spectroscopy, it is demonstrated that: 1) The oxygen plasma completely removes the polymer, though conserving the original order of the micellar array. Furthermore, the resulting nanoparticles are entirely oxidized with a chemical shift of the Co 2p3/2 line pointing to the formation of Co3O4. 2) By the subsequent hydrogen plasma treatment the nanoparticles are fully reduced to metallic Co. 3) By exposing the pure Co nanoparticles for 100 s to various oxygen partial pressures pequation/tex2gif-inf-5.gif, a stepwise oxidation is observed with a still metallic Co core surrounded by an oxide shell. The data allow the extraction of the thickness of the oxide shell as a function of the total exposure to oxygen (pequation/tex2gif-inf-7.gif × time), thus giving the opportunity to control the ferromagnetic–antiferromagnetic composition of an exchange‐biased magnetic system. 相似文献
10.
A. K. Hansen A. C. Boxer J. L. Ellsworth D. T. Garnier I. Karim J. Kesner M. E. Mauel E. E. Ortiz 《Journal of Fusion Energy》2007,26(1-2):57-60
Plasmas in the Levitated Dipole Experiment (LDX) are formed and sustained currently via two electron cyclotron resonance heating
(ECRH) sources: 2.5 kW at 2.45 GHz and 2.5 kW at 6.4 GHz. An important topic being investigated is how varying the ECRH affects
the confinement and stability of the plasma. We report the results of using different operational combinations of our RF sources,
such as varying the power composition, changing the power levels, and sequencing of the onset time. 相似文献