全文获取类型
收费全文 | 1268篇 |
免费 | 9篇 |
专业分类
电工技术 | 5篇 |
综合类 | 2篇 |
化学工业 | 67篇 |
金属工艺 | 7篇 |
机械仪表 | 9篇 |
建筑科学 | 10篇 |
能源动力 | 8篇 |
轻工业 | 41篇 |
水利工程 | 1篇 |
无线电 | 41篇 |
一般工业技术 | 57篇 |
冶金工业 | 990篇 |
原子能技术 | 3篇 |
自动化技术 | 36篇 |
出版年
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 29篇 |
2012年 | 6篇 |
2011年 | 18篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 10篇 |
2007年 | 15篇 |
2006年 | 11篇 |
2005年 | 13篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 36篇 |
1998年 | 297篇 |
1997年 | 176篇 |
1996年 | 103篇 |
1995年 | 69篇 |
1994年 | 55篇 |
1993年 | 62篇 |
1992年 | 15篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 8篇 |
1988年 | 17篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 28篇 |
1976年 | 53篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1971年 | 4篇 |
排序方式: 共有1277条查询结果,搜索用时 0 毫秒
61.
Laureano?LambánEmail author Vico?Pascual Julio?Rubio 《Applicable Algebra in Engineering, Communication and Computing》2003,14(3):187-215
In a previous paper we characterized, in the Category Theory setting, a class of implementations of Abstract Data Types, which has been suggested by the way of programming in the EAT system. (EAT, Effective Algebraic Topology, is one of Sergeraerts systems for effective homology and homotopy computation.) This characterization was established using classical tools, in an unrelated way to the current mainstream topics in the field of Algebraic Specifications. Looking for a connection with these topics, we have found, rather unexpectedly, that our approach is related to some object-oriented formalisms, namely hidden specifications and the coalgebraic view. In this paper, we explore these relations making explicit the implicit object-oriented features of the EAT system and generalizing the data structure analysis we had previously done. 相似文献
62.
Thomas Lamb 《CAD/CAM与制造业信息化》2007,(1):6-8
近年来,世界造船中心正从欧美等高成本国家向东南亚转移,我国船舶工业正面临巨大的发展机遇和挑战.在这一大环境下,依靠我国完善的工业基础和强大的综合国力,依靠政府的大力扶植,我国船舶工业飞速发展,并已经具有了成熟的国际市场竞争经验,一跃成为世界第三造船大国. 相似文献
63.
MM Berenson TD Johnson NR Markowitz KN Buchi WS Samowitz 《Canadian Metallurgical Quarterly》1993,104(6):1686-1691
BACKGROUND: Antireflux therapy has generally failed to induce regression of Barrett's epithelium. It was hypothesized that squamous epithelium could be restored if the columnar tissue was ablated while gastric acid secretion was suppressed. METHODS: Ten white men with Barrett's esophagus received 40 mg of omeprazole daily. Thereafter, every 2-5 weeks they underwent videotaped endoscopies to argon laser photoablate columnar tissue, obtain biopsy specimens, and assess results. Squamous re-epithelialization was assessed by correlation of videotapes and directed biopsies. RESULTS: Patients had one to eight areas ablated, totaling 0.5-12.0 cm2. Videotape assessments were corroborated by biopsy in all but one instance. Thirty-eight of 40 treatment locations partially or completely re-epithelialized with squamous tissue. Squamous regrowth appeared to occur by spread from contiguous squamous borders and de novo from glandular tissue. Regrowth was influenced by the extent of squamous borders and completeness of ablations. Nonablated glandular tissue persisted beneath squamous epithelium. CONCLUSIONS: Ablation of Barrett's epithelium and suppression of acid secretion facilitated squamous re-epithelialization. A progenitor cell within the metaplastic tissue has the potential to differentiate normally. 相似文献
64.
Identification of a gene that causes primary open angle glaucoma 总被引:3,自引:0,他引:3
EM Stone JH Fingert WL Alward TD Nguyen JR Polansky SL Sunden D Nishimura AF Clark A Nystuen BE Nichols DA Mackey R Ritch JW Kalenak ER Craven VC Sheffield 《Canadian Metallurgical Quarterly》1997,275(5300):668-670
Glaucoma is a major cause of blindness and is characterized by progressive degeneration of the optic nerve and is usually associated with elevated intraocular pressure. Analyses of sequence tagged site (STS) content and haplotype sharing between families affected with chromosome 1q-linked open angle glaucoma (GLC1A) were used to prioritize candidate genes for mutation screening. A gene encoding a trabecular meshwork protein (TIGR) mapped to the narrowest disease interval by STS content and radiation hybrid mapping. Thirteen glaucoma patients were found to have one of three mutations in this gene (3.9 percent of the population studied). One of these mutations was also found in a control individual (0.2 percent). Identification of these mutations will aid in early diagnosis, which is essential for optimal application of existing therapies. 相似文献
65.
Characterising heave,pitch, and roll motion of road vehicles with principal component and frequency analysis 下载免费PDF全文
Michael Thomas Long Vincent Rouillard Matthew James Lamb Michael Andrej Sek 《Packaging Technology and Science》2018,31(1):3-13
For the great majority of transport vehicles, the magnitude of the heave vibration is generally more severe than pitch and roll. Consequently, the measurement, analysis, and simulation of the vehicle vibrations have been focused on vertical vibration. Despite this, it is now being increasingly recognised that the combination of heave, pitch, and roll vibratory motion can induce more severe damage to shipments than vertical vibration alone. Although the pitch and roll motion of road vehicles can now be readily measured, there is little information on how to analyse the data to produce meaningful statistical relationships between the three variables. This paper builds upon previous work that showed that there is some correlation between pitch, roll, and heave motion and that these relationships are dependent on vehicle geometry, including payload mass, centre of mass, vehicle roll centre, and moments of inertia as well as vehicle speed and the road surface. In this paper, data from a range of quasi‐controlled experiments, which involved driving vehicles at constant‐speed on selected roads, were analysed using principal component analysis as well as frequency domain analysis to reveal the relationship between heave, pitch, and roll motion. This was undertaken for a variety of vehicle speeds and routes in order to establish if they influence pitch and roll response. Results are presented in the form of distribution functions, statistical coefficients, and frequency response functions, all of which are useful for helping to define parameters for the simulation of complete, three‐axis vibrations using multi‐axis vibration test systems. 相似文献
66.
67.
To understand how mammalian herbivores process plant secondary compounds, we examined differences in expression of biotransformation enzyme mRNAs among populations of wild woodrats (Neotoma lepida) and laboratory rats. We compared expression of mRNAs for 10 biotransforming enzymes in five families (CYP, mEH, QOR, GST, and UGT) by using Northern blot analysis. We found significant differences in eight of 10 mRNAs tested. We suggest that the differences in mRNA expression among populations of woodrats and laboratory rats may be due to differences in the secondary compound composition of their diets. Our results provide background for future studies of detoxification strategies in mammalian herbivores that combine pharmacological techniques with an ecological perspective. 相似文献
68.
Previous research has indicated that abstinence early in a smoking cessation program is predictive of successful posttreatment abstinence. However, it has not been established whether or not this effect is independent of other in-treatment abstinence patterns. In this paper the relationship between three potentially important aspects of in-treatment smoking abstinence and posttreatment smoking abstinence are examined: early abstinence, extended abstinence, and end-of-treatment abstinence. We examined the relationship between smoking behavior measured each weekday over 70 visits (approximately 14 weeks) of a contingency management smoking cessation program and at a follow-up visit 6 months after study entry (3 months after the scheduled end of treatment). Ninety-five of 102 participants were successfully followed-up. Seven of these 95 participants were confirmed abstinent. Early abstinence, defined as abstinence during the first 10 treatment visits, was significantly and independently related to follow-up abstinence (OR = 56.67 [7.29–440.63]). Extended abstinence and end-of-treatment abstinence were related to follow-up abstinence, but not independent of early abstinence based on multiple regression models. Inclusion of a variety of demographic and environmental characteristics did not significantly alter this relationship. Thus, consistent with the previous literature, the establishment of early abstinence appears to be crucial to establishing longer-term abstinence, independent of other in-treatment abstinence patterns. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
69.
Silica-supported Pd clusters were characterized by in situ EXAFS spectroscopy. Clusters with an average nuclearity of six atoms were derived from either an inorganic or an organometallic precursor by reduction at 100–150C. Despite the small size of the clusters, EXAFS contributions from the metal-support interface were not detected. These clusters and larger ones formed by reduction at 320C absorb hydrogen on cooling in H2 to 30C; the resultant interstitial hydride species decompose in vacuo at 30C. Vacuum treatment at 300C removes chemisorbed H2 yielding bare Pd clusters. In contrast to larger crystallites, the Pd clusters do not react with C2H4 at 150 to form interstitial carbide species. 相似文献
70.
Hildo J. Lamb 《Magma (New York, N.Y.)》2000,11(1):75-77
4. Conclusions Severe aortic valve stenosis leads to a decreased myocardial PCr/ATP, and to impairment of LV diastolic function. Following
aortic valve replacement, myocardial PCr/ATP normalizes completely, whereas LV diastolic function improves significantly.
Moreover, there is an association between altered myocardial HEP metabolism and impaired LV diastolic function. 相似文献