全文获取类型
收费全文 | 367篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 3篇 |
综合类 | 6篇 |
化学工业 | 12篇 |
金属工艺 | 2篇 |
机械仪表 | 5篇 |
建筑科学 | 4篇 |
能源动力 | 2篇 |
轻工业 | 18篇 |
石油天然气 | 1篇 |
无线电 | 3篇 |
一般工业技术 | 8篇 |
冶金工业 | 304篇 |
自动化技术 | 3篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 13篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 4篇 |
1999年 | 8篇 |
1998年 | 108篇 |
1997年 | 48篇 |
1996年 | 25篇 |
1995年 | 20篇 |
1994年 | 13篇 |
1993年 | 24篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1977年 | 9篇 |
1976年 | 19篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有371条查询结果,搜索用时 15 毫秒
1.
DH Kang CL Coe DO McCarthy NN Jarjour EA Kelly RR Rodriguez WW Busse 《Canadian Metallurgical Quarterly》1997,17(8):481-487
T cell cytokines play an important role in mediating airway inflammation in asthma. The predominance of a Th2 cytokine profile, particularly interleukin (IL)-4 and IL-5, is associated with the pathogenesis and course of asthma. The aim of this study was to test the hypothesis that a stressful life event alters the pattern of cytokine release in asthmatic individuals. Thirteen healthy controls and 21 asthmatic adolescents gave blood samples three times over a semester: midsemester, during the week of final examinations, and 2-3 weeks after examinations. Interferon-gamma (IFN-gamma), IL-2, IL-4, and IL-5 were measured from supernatants of cells stimulated with PHA/PMA for 24 h. Cells from asthmatic subjects released significantly more IL-5 during the examination and postexamination periods, whereas cells from healthy controls released significantly more IL-2 during the midsemester and examination periods, thereby indicating a bias for a Th2-like pattern in asthmatics and a Th1-like pattern in healthy controls. IL-4 and IL-5 production showed a marked decrease during and after examinations in healthy controls, whereas this decline was absent in asthmatics. The ratios of IFN-gamma:IL-4 and IFN-gamma:IL-5 also revealed significant changes in the profile of cytokine release across the semester. These results indicate differential cytokine responses in asthmatics that may become pronounced during periods of cellular activation. 相似文献
2.
BACKGROUND: Laparoscopic Nissen fundoplication is an effective procedure for the treatment of gastro-oesophageal reflux disease (GORD), but the underlying motility mechanisms that explain the success of this operation remain unclear. METHODS: Twenty patients with a history of GORD underwent stationary oesophageal manometry and prolonged ambulatory pH monitoring, both before and 3 months after fundoplication. RESULTS: Eighteen patients were completely cured of reflux symptoms and stopped all antireflux medication after operation. After fundoplication there was a significant increase (P < 0.01) in median resting lower oesophageal sphincter (LOS) pressure and length. Median residual LOS pressure during swallow-induced LOS relaxation also increased significantly after operation (P < 0.01). The number of reflux episodes decreased from a median of 48 to 3 after fundoplication (P < 0.01). The time at pH less than 4 decreased from 5.7 to 0 per cent in the supine position (P < 0.01), and from 9.8 to 0.2 per cent while upright (P < 0.001). CONCLUSION: Early subjective results at 3 months following laparoscopic antireflux surgery show improved symptoms. One of the mechanisms underlying the antireflux action of fundoplication is an increase in median residual LOS pressure at the gastro-oesophageal junction. This may be a purely mechanical effect of the fundic wrap extrinsic to the LOS. 相似文献
3.
JW DiFiore DO Fauza R Slavin CA Peters JC Fackler JM Wilson 《Canadian Metallurgical Quarterly》1994,29(2):248-56; discussion 256-7
Infants with congenital diaphragmatic hernia (DH) and profound pulmonary hypoplasia are currently unsalvageable. The authors previously demonstrated that tracheal ligation (TL) accelerates fetal lung growth and reverses the pulmonary hypoplasia of fetal nephrectomy. The purpose of this study was to determine if the pulmonary hypoplasia of experimental DH could be similarly reversed and, if so, whether the resulting lungs would show better function than those of their DH counterparts. Eighteen fetal lambs were divided into three experimental groups of six animals each. In group 1, DH was created at 90 days' gestation. In group 2, DH was created at 90 days' gestation and TL performed during the same operation. Group 3 consisted of sham-operated controls. These animals were delivered near full-term, and their lungs analyzed by standard morphometric techniques. Ten additional fetal lambs were divided into two experimental groups of five animals each. In group 4, DH was created at 90 days' gestation. In group 5, DH was created at 90 days' gestation and TL performed 20 days later, at 110 days' gestation. These animals were pressure-ventilated via tracheostomy over a 2-hour period in which PaO2, PaCO2, and compliance were measured. Intratracheal pressure (ITP) was measured at the time of delivery in all groups. Upon retrieval, DH animals had abdominal viscera in the chest and small lungs; in contrast, DH/TL animals had the herniated viscera reduced from the chest by enlarged lungs. DH/TL lungs showed markedly increased growth, with significant increases in lung volume:body weight ratio (LV:BW; P = .0001), alveolar surface area (ALV.SA; P = .0001), and alveolar number (ALV#) (P = .0001) when compared with those of the DH or control group. This growth was associated with a normal maturation pattern based on histological appearance, normal airspace fraction, and normal alveolar numerical density. ITP in the DH/TL group was increased when compared with that of DH and control animals (P = .0001). Total lung DNA and protein were both elevated in the DH/TL animals (P = .0001). However, the DNA:protein ratio remained normal, suggesting lung growth had occurred through cell proliferation, not by hypertrophy. When ventilated over a range of settings, DH/TL lungs were more compliant (P = .0001) and achieved higher PaO2s (P < .003) and lower PaCO2s (P = .0001) than their DH counterparts. From these data, the authors conclude: (1) Experimental fetal DH produces hypoplastic lungs that are not capable of adequate gas exchange with conventional ventilation.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
4.
When one wants to understand and model the drying of high water content gels, one needs to gather all thermal physical parameters and to derive a physical model based on independently measured parameters. We chose to work experimentally and theoretically on water diffusion and drying of spheres of polyacrylamide gel.
We have demonstrated the strong influence of vitreous transition on the relationship of water diffusivity with moisture content. Values of the diffusion coefficient and temperature shift factor for diffusion have been proposed.
Convective and micro-wave drying kinetics show the presence of a drying phase purely specific to radiation absorption. Finally, we have proposed a mathematical model containing independent physical parameters, which' not only predicts mass fluxes but also analyses critical physical phenomena. 相似文献
We have demonstrated the strong influence of vitreous transition on the relationship of water diffusivity with moisture content. Values of the diffusion coefficient and temperature shift factor for diffusion have been proposed.
Convective and micro-wave drying kinetics show the presence of a drying phase purely specific to radiation absorption. Finally, we have proposed a mathematical model containing independent physical parameters, which' not only predicts mass fluxes but also analyses critical physical phenomena. 相似文献
5.
Autosomal dominant polycystic kidney disease (ADPKD) is a systemic disorder with a variety of cardiovascular manifestations. This study presents a group of patients with ADPKD who had intracranial arterial dolichoectasia. One hundred seventy-eight ADPKD patients were screened with magnetic resonance angiography, 40 ADPKD patients had conventional angiography, and 98 ADPKD patients underwent a brain autopsy. For comparison, 360 patients without ADPKD who had magnetic resonance angiography and conventional angiography or brain autopsy were also studied. The prevalence of asymptomatic intracranial arterial dolichoectasia was 2.2% (4 of 178), 2.5% (1 of 40), and 2.0% (2 of 98) in the three ADPKD groups, respectively. None of the patients without ADPKD had intracranial arterial dolichoectasia. In addition to the seven patients with asymptomatic disease, two ADPKD patients with vertebrobasilar dolichoectasia had posterior circulation ischemic symptoms. The mean age of the nine patients (five men and four women) was 56.6 yr (range, 41 to 67 yr). The posterior circulation was involved in five patients, the anterior circulation was involved in two patients, and both were involved in two patients. Arterial dissection was believed to have caused middle cerebral artery dolichoectasia in one patient, and intracranial arterial dissections were strongly suspected in two other patients. Six of the nine patients with intracranial arterial dolichoectasia had additional vascular manifestations of ADPKD. Some patients with ADPKD are at an increased risk of developing intracranial arterial dolichoectasia and dissections. Recognizing this association is important because (1) it may be a cause of stroke; (2) it may mimic a saccular aneurysm on radiographic studies; and (3) it suggests that the arteriopathy of ADPKD may be more generalized than previously believed. 相似文献
6.
An inhibition ELISA (IH-ELISA) test for foot-and-mouth disease virus (FMDV) was validated using 106 epithelial samples from suspected cases of FMD in Argentina submitted to the Argentine National Diagnostics Laboratory (GELAB) over a period of 12 months and examined in parallel with the complement fixation test (CFT). IH-ELISA was found to be more sensitive, detecting 25% (26 samples) more FMDV positives than the CFT in original suspensions of field samples. The effect of storage conditions on 12S stability was examined. Plates stored at 4 degrees C blocked with 1% ovalbumin and plates stored at -20 degrees C with or without blocking buffer could be used for at least 90 days. When various brands of polystyrene plates were compared for 12ps adsorption it was found that those microplates of higher binding capacity were more efficient. 相似文献
7.
DO Warner 《Canadian Metallurgical Quarterly》1998,88(6):1433-1434
8.
Magossi Maiara S. Maraldi Vitor A. Magossi Mariana S. DA Costa Fabíola M. Alves Kamilla Franco Fernanda D. S. DO Carmo Devaney R. 《SILICON》2021,13(7):2243-2255
Silicon - This study describes the preparation and characterization of 3-chloropropyl silica gel with 4-amino-5-(4pyridyl)-4H-1,2,4-triazole-3-thiol (SGA) for copper adsorption in different media.... 相似文献
9.
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
10.
A recent intracellular study of dorsal cochlear nucleus (DCN) neurons in vitro by Manis [P. B. Manis, J. Neurosci. 10, 2338-2351 (1990)] suggests that the expression of the pause-build discharge pattern is in large part dependent on hyperpolarization of their membrane potentials in a period just preceding a depolarizing stimulus ("hyperpolarization conditioning" hypothesis). Our examination of the activity of a sample of pause-build units (n = 72) revealed suppression of discharge activity during a time window of the silent interstimulus interval (SII) just preceding the tone burst relative to the spontaneous rate in 74% of all units. The discharge suppression of a subset of DCN pause-build units in the SII satisfies a requirement of the "hyperpolarization conditioning" hypothesis, and thus supports the hypothesis. 相似文献