全文获取类型
收费全文 | 2580篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 11篇 |
综合类 | 1篇 |
化学工业 | 49篇 |
金属工艺 | 3篇 |
机械仪表 | 4篇 |
建筑科学 | 16篇 |
能源动力 | 16篇 |
轻工业 | 66篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 81篇 |
一般工业技术 | 68篇 |
冶金工业 | 2226篇 |
原子能技术 | 4篇 |
自动化技术 | 36篇 |
出版年
2021年 | 8篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 11篇 |
2012年 | 7篇 |
2011年 | 15篇 |
2010年 | 11篇 |
2009年 | 17篇 |
2008年 | 14篇 |
2007年 | 14篇 |
2006年 | 9篇 |
2005年 | 12篇 |
2004年 | 5篇 |
2003年 | 22篇 |
2002年 | 10篇 |
2001年 | 18篇 |
2000年 | 9篇 |
1999年 | 78篇 |
1998年 | 740篇 |
1997年 | 428篇 |
1996年 | 271篇 |
1995年 | 155篇 |
1994年 | 124篇 |
1993年 | 145篇 |
1992年 | 23篇 |
1991年 | 24篇 |
1990年 | 19篇 |
1989年 | 21篇 |
1988年 | 33篇 |
1987年 | 26篇 |
1986年 | 13篇 |
1985年 | 21篇 |
1984年 | 4篇 |
1983年 | 12篇 |
1982年 | 17篇 |
1981年 | 13篇 |
1980年 | 23篇 |
1979年 | 4篇 |
1978年 | 13篇 |
1977年 | 50篇 |
1976年 | 97篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1970年 | 3篇 |
1955年 | 1篇 |
排序方式: 共有2585条查询结果,搜索用时 862 毫秒
81.
JD Reveille GS Alarcón SE Fowler SR Pillemer R Neuner DO Clegg IS Mikhail DE Trentham JC Leisen G Bluhm SM Cooper H Duncan M Tuttleman SP Heyse JT Sharp B Tilley 《Canadian Metallurgical Quarterly》1996,39(11):1802-1807
OBJECTIVE: To examine the effect of alleles encoding the "shared"/"rheumatoid" epitope on rheumatoid arthritis (RA) disease severity in patients who participated in the minocycline in RA (MIRA) trial. METHODS: Of 205 patients with a week-48 visit, blood was available for typing of HLA-DRB1 and HLA-DQB1 in 174 (85%) and successfully completed in 169 (82%). Baseline erosions were used to assess disease severity and new erosions at the last visit served as a proxy for progression. RESULTS: At baseline, there was no association between the presence of erosive disease or rheumatoid factor status and the dose of rheumatoid epitope (homozygous, heterozygous, none) or the specific alleles identified. At the final visit, a gradient was observed for the 3 allelic subgroups (and their gene doses) in the occurrence of new erosions among the Caucasian placebo-treated, but not the minocycline-treated, patients. A treatment group/HLA-DR4 epitope interaction was demonstrated in multivariate analyses. Approximately two-thirds of African-American patients did not have the rheumatoid epitope. CONCLUSION: HLA-DRB1 oligotyping may be useful in predicting the progression of disease in some Caucasian patients. Our study corroborates the infrequency of the epitope among African-American patients with RA. 相似文献
82.
Perinuclear antineutrophil cytoplasmic antibodies in patients with Crohn's disease define a clinical subgroup 总被引:1,自引:0,他引:1
EA Vasiliauskas SE Plevy CJ Landers SW Binder DM Ferguson H Yang JI Rotter A Vidrich SR Targan 《Canadian Metallurgical Quarterly》1996,110(6):1810-1819
BACKGROUND & AIMS: Antineutrophil cytoplasmic antibodies (ANCA) have been consistently detected in a subgroup of patients with Crohn's disease (CD). This study was designed to determine whether serum ANCA expression in patients with CD characterizes an identifiable clinical subgroup. METHODS: The study population consisted of 69 consecutive patients with an established diagnosis of CD as determined by a combination of characteristic clinical, radiographic, endoscopic, and histopathologic criteria. Sera from the patients were analyzed for the presence of ANCAs using the fixed neutrophil enzyme-linked immunosorbent assay (ELISA) assay. Perinuclear ANCA (pANCA)-positive and cytoplasmic ANCA (cANCA)-positive results by ELISA were confirmed by indirect immunofluorescence staining. Clinical profiles of the ANCA-positive patients with CD were compared with those of patients with CD not expressing ANCA (ANCA-negative). RESULTS: pANCA-positive patients with CD have endoscopically and/or histopathologically documented left-sided colitis and symptoms of left-sided colonic inflammation, clinically reflected by rectal bleeding and mucus discharge, urgency, and treatment with topical agents. One hundred percent of patients with CD expressing pANCA had "UC-like" features. CONCLUSIONS: In patients with CD, serum pANCA expression characterizes a UC-like clinical phenotype. Stratification of CD by serum pANCA provides evidence of heterogeneity within CD and suggests a common intestinal mucosal inflammatory process among a definable subgroup of patients with CD and UC expressing this marker. 相似文献
83.
84.
N M Ferguson C A Donnelly J Hooper A C Ghani C Fraser L M Bartley R A Rode P Vernazza D Lapins S L Mayer R M Anderson 《Journal of the Royal Society Interface》2005,2(4):349-363
We analyse data on patient adherence to prescribed regimens and surrogate markers of clinical outcome for 168 human immunodeficiency virus infected patients treated with antiretroviral therapy. Data on patient adherence consisted of dose-timing measurements collected for an average of 12 months per patient via electronic monitoring of bottle opening events. We first discuss how such data can be presented to highlight suboptimal adherence patterns and between-patient differences, before introducing two novel methods by which such data can be statistically modelled. Correlations between adherence and subsequent measures of viral load and CD4+T-cell counts are then evaluated. We show that summary measures of short-term adherence, which incorporate pharmacokinetic and pharmacodynamic data on the monitored regimen, predict suboptimal trends in viral load and CD4+T-cell counts better than measures based on adherence data alone. 相似文献
85.
T. W. Tsuei R. L. Wood C. Khan Malek M. M. Donnelly R. B. Fair 《Microsystem Technologies》1998,4(4):201-204
A method for creating angled structures for use in microvalve devices applicable to control of liquid flow is presented.
This technique utilizes a modified LIGA process with successive angled and rotated exposures into free standing acrylic sheets
to form a tapered valve seat structure. These valve seats are integrated with bulk micromachined silicon diaphragms and tapered
PMMA valve bosses to complete the microvalve. The long term goal of this research effort is to develop a normally-closed,
low power, microfabricated valve for use in an implantable drug delivery system. This paper reports on the design and fabrication
of microvalves using off-axis LIGA exposures. Flow testing and fluid handling characterization results are also presented.
Received: 25 August 1997 Accepted: 22 October 1997 相似文献
86.
Arvind Jayaprakash Jin-Keun Choi Georges L. Chahine Farrel Martin Martin Donnelly Jean-Pierre Franc Ayat Karimi 《Wear》2012,274(1-2):619-629
Cavitation erosion prediction and characterization of cavitation field strength are of interest to industries suffering from cavitation erosion detrimental effects. One means to evaluate cavitation fields and materials is to examine pitting rates during the incubation period, where the test sample undergoes localized permanent deformations shaped as individual pits. In this study, samples from three metallic materials, an Aluminum alloy (Al 7075), a Nickel Aluminum Bronze (NAB) and a Duplex Stainless Steel (SS A2205) were subjected to a vast range of cavitation intensities generated by cavitating jets at different driving pressures and by an ultrasonic horn. The resulting pitted sample surfaces were examined and characterized with a non-contact 3D optical scanner and the resulting damage computer-analyzed. A statistical analysis of the pit population and its characteristics was then carried out. It was found that the various cavitation field strengths can be correlated to the measured pit distributions and that two characteristic quantities: a characteristic number of pits per unit surface area and unit time, and a characteristic pit diameter or a characteristic pit depth can be attributed to a given “cavitation intensity level”. This characterization concept can be used in the future to study the cavitation intensity of the full scale and to develop methods of full scale predictions based on model scale erosion data. 相似文献
87.
88.
89.
LUC SARRAZIN THéRèSE SCHEMBRI PIERRE REBOUILLON 《The International journal of environmental studies》2013,70(4):413-425
A selective method for determining polycyclic aromatic hydrocarbons (PAHs) in sediments using solid‐phase extraction and RP‐HPLC with fluorescence and UV detection is described. The complete analytical method is used to surface sediments from the creek of Cortiou (France). Sewage from the urban area of Marseille is delivered to the creek. PAH levels in sediments (µg/g) range between 2.251 µg/g (for the benzo(a)anthracene) and 0.001 µg/g. The flux of pollution provided by the outfall is preferentially oriented from East to West by the Liguro‐Provenalcal current. The significant values are mainly confined on a perimeter of 2 km around the outfall. The phenanthrene/anthracene and fluoranthene/pyrene ratios indicate pyrolytic and petrogenic contamination. The particulate size observations concerning the sediments show that oxygenated sandy zones, where eliminating mechanisms (desorption, biodegradation) take place, are mainly located on the Chêvres plateau and around Jarre, Plane and Riou Islands. 相似文献
90.
Colour removal from a simulated dye wastewater using a two-phase anaerobic packed bed reactor 总被引:12,自引:0,他引:12
In recent years, rapid technological advances in the textile and dyeing industry have yielded benefits to society but have also generated new and significant environmental problems. The treatment alternatives applicable for the removal of colour vary, depending upon the type of dye wastewater. A synthetic, simulated mixed dye waste (Basic Yellow 28, Basic Yellow 21, Basic Red 18.1, Basic Violet Red 16, Basic Red 46, Basic Blue 16, Basic Blue 41) representing a known waste from a fibre production factory, was investigated. The biological process of anaerobic digestion has been recognised as a simple and energy-efficient means of treating and stabilising a wide range of organic industrial wastewaters. This study sets out to demonstrate the effect of different loading rates, dye concentrations and hydraulic retention times (HRTs) on colour removal efficiency under mesophilic anaerobic conditions. The reactor was operated under mesophilic conditions at different organic loading rates (OLRs) and HRTs for nine months. The results of this study show that a 2-stage mesophilic anaerobic up-flow packed bed reactor can remove up to 90% of the colour from a mixed cationic dye containing 1000 mg/l of dye. Colour removal efficiency falls as the influent dye concentration increases, but rises with increased hydraulic retention time and increased organic loading. The primary colour removal mechanism was one of biosorption with subsequent biodegradation. Acetoclastic methanogens were moderately inhibited at low organic loading rates of 0.25 kg COD/m3 d, at which level, acidogenesis and acetogenesis appeared to be unaffected. Inhibition of acidogenesis became marked at higher OLRs (1 kg COD/m3 d) and when the HRT was reduced from 5 to 3 days. 相似文献