全文获取类型
收费全文 | 1787篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 6篇 |
轻工业 | 5篇 |
石油天然气 | 1篇 |
一般工业技术 | 1篇 |
冶金工业 | 1776篇 |
自动化技术 | 2篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2018年 | 2篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2009年 | 1篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2000年 | 1篇 |
1999年 | 71篇 |
1998年 | 609篇 |
1997年 | 345篇 |
1996年 | 207篇 |
1995年 | 114篇 |
1994年 | 71篇 |
1993年 | 123篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 16篇 |
1978年 | 3篇 |
1977年 | 27篇 |
1976年 | 73篇 |
1975年 | 3篇 |
1954年 | 1篇 |
排序方式: 共有1792条查询结果,搜索用时 15 毫秒
171.
Obtaining high-quality radiographs of the proximal aspect of equine limbs is difficult because of the large muscles in these regions. The use of scintigraphy may provide further information. Abnormal bone scan findings of the ischial tuberosity or the third trochanter were found in 29 adult horses with obscure hind limb lameness between 1986 and 1996 at the Large Animal Clinic of the University of Bern. Each had abnormal radiopharmaceutical uptake but not all had radiographic changes. Radiopharmaceutical uptake ratios between the ischial tuberosity and the greater trochanter were calculated. The uptake ratio in a control group of 11 clinically sound horses was lower than in 11 lame horses with subjectively enhanced radiopharmaceutical uptake. 相似文献
172.
A range of different drugs can cause renal problems, and reactions to the radiocontrast material administered for diagnostic tests are well known. This review describes factors that put patients at risk of kidney damage from drug use and outlines how to clinically diagnose adverse reactions. The most appropriate way to deal with drug-induced renal toxicity is through prevention. 相似文献
173.
Class I presentation of microinjected native OVA by a temperature-sensitive ubiquitin conjugation mutant, ts85, but not wild-type murine cells, was markedly inhibited following incubation at a nonpermissive temperature. In contrast, the nonpermissive temperature did not affect class I presentation of a minimal OVA peptide expressed in the cytosol. Therefore, these results provide a second example in which a temperature sensitive mutation in the ubiquitin conjugation pathway inhibits MHC class I presentation of native OVA. Surprisingly, incubation at the nonpermissive temperature did not inhibit class I presentation of chemically denatured and alkylated OVA microinjected into the cytosol of mutant cells. Similarly, the presentation of endogenously synthesized OVA (which is expressed from a recombinant vaccinia virus and, presumably, is misfolded in the cytosol) was also not inhibited in both mutant cell lines. Methylation of the lysine groups in denatured OVA, which blocks ubiquitin conjugation, reduced but did not eliminate the presentation of denatured OVA, providing evidence for both ubiquitin-dependent and ubiquitin-independent pathways for class I presentation. In contrast, a proteasome inhibitor blocked class I presentation of all forms of OVA, while a control peptide aldehyde was not inhibitory. These results indicate that modification of the structure of a protein can influence its requirements for ubiquitin conjugation for efficient class I presentation, with the key alteration possibly being the loss of proper conformation. However, regardless of the form of the Ag, the proteasome appears to be required for generating peptides from both endogenously synthesized and microinjected OVA for class I presentation. 相似文献
174.
GR Davies N Banatvala CE Collins MT Sheaff Y Abdi L Clements DS Rampton 《Canadian Metallurgical Quarterly》1994,29(5):419-424
Helicobacter pylori infection has been associated with stimulation of gastric mucosal reactive oxygen metabolite production. To provide further evidence of a causal relationship we looked for a dose-response relationship. We studied antral biopsy material from 110 patients. Quantitative H. pylori assessments were made using histologic and microbiologic methods. Reactive oxygen metabolite production was measured by luminol-dependent chemiluminescence. The usefulness of timed urease test colour changes as a guide to infective load was assessed. There was a positive association between mucosal reactive oxygen metabolite production and histologic (p = 0.002, n = 69) and microbiologic (Spearman's R = +0.6, p = 0.05, n = 18) quantitative H. pylori assessments. H. pylori infective load varied markedly over small areas (coefficient of repeatability of paired cultures (in colony-forming units/mg) = 1.9 x 10(6). Urease test timing correlated with histologic (p = 0.01) and microbiologic (p = 0.03) H. pylori quantitation. Histologically assessed mucosal damage was related to quantitative H. pylori assessment and to mucosal reactive oxygen metabolite production (p = 0.0001). These results support the hypothesis that H. pylori stimulates gastric mucosal reactive oxygen metabolite production and that this phenomenon is of pathogenic importance. 相似文献
175.
L Arreguín Osuna R García Caballero MT Montero Cortés I Ortiz Aldana 《Canadian Metallurgical Quarterly》1998,45(3):7-11
OBJECTIVE: To compare the efficacy and safety of levocabastine nasal spray asid cetirizine oral for the treatment of perennial allergic rhinitis in children. MATERIAL AND METHODS: In this randomized, prospective experimental, open clinical trial. We studied 30 children with ages between 6 and 16 years with perennial allergic rhinitis. Group 1, 17 subjects (7 female, 10 male) received cetirizine once daily, 5 mg children weientig less dian 30 k asid 10 mg in children weighing more trw' 30 k during 15 days. Group 2, 13 subjects (7 male, 6 female) received levocabastine 2 puffs BID on each nostril during tbe same time. A nasal symptoms score, nasal peal: flow vid eosinophils in a nasal smear were performed before and after treatment. RESULTS: There were no statistical differences in age, weight, height and arid duration of symptoms. Both groups showed improvement of symptoms via nasal peak flow with no differences between them (intergroup); nasal eosinophils remained unchanged. We for third statistical differences pre vid postreatment in each group (intragroup): Group 1, nasal congestion p = 0.002, ocular itch p = 0.01, sneezing p = 0.007, nasal secretion p = 0.01, nasal itch O = 0.009, total points O = 0.0005. Group 2, nasal congestion O = 0.02, ocular itch p = 0.05, sneezing p = 0.01, nasal secretion p = 0.01, nasal itch p = 0.04, total points p = 0.005. Significant differences were found in nasal peal' flow in Group 1 (p = 0.01) but no differences in eosinophils between file two groups. Side effects: 3 subjects in Group 1 (drowsiness, 1 appetite increase said 1 rhinorrea with epistaxis) vide 1 in Group 2 sensation of facial edema. CONCLUSION: Bofil drugs are effective the clinical relief of symptoms of perennial allergic rhinitis in children vied levocabastine has less side effects. 相似文献
176.
DD Bigner MT Brown AH Friedman RE Coleman G Akabani HS Friedman WL Thorstad RE McLendon SH Bigner XG Zhao CN Pegram CJ Wikstrand JE Herndon NA Vick N Paleologos I Cokgor JM Provenzale MR Zalutsky 《Canadian Metallurgical Quarterly》1998,16(6):2202-2212
PURPOSE: To determine the maximum-tolerated dose (MTD) of iodine 131 (131I)-labeled 81C6 monoclonal antibody (mAb) in brain tumor patients with surgically created resection cavities (SCRCs) and to identify any objective responses to this treatment. METHODS: In this phase I trial, eligible patients were treated with a single injection of 131I-labeled 81C6. Cohorts of three to six patients were treated with escalating dosages of 131I (starting dose of 20 mCi with a 20-mCi escalation in subsequent cohorts) administered through an Ommaya reservoir in the SCRC. Patients were followed up for toxicity and response until death or for a minimum of 1 year after treatment. The SCRC patients, who were previously irradiated, were followed up without additional treatment unless progressive disease was identified. RESULTS: We administered 36 treatments of 131I doses up to 120 mCi to 34 previously irradiated patients with recurrent or metastatic brain tumors. Dose-limiting toxicity was reached at 120 mCi and was limited to neurologic or hematologic toxicity. None of the patients treated with less than 120 mCi developed significant neurologic toxicity; one patient developed major hematologic toxicity (MHT). The estimated median survival for patients with glioblastoma multiforme (GBM) and for all patients was 56 and 60 weeks, respectively. CONCLUSION: The MTD for administration of 131I-labeled 81C6 into the SCRCs of previously irradiated patients with recurrent primary or metastatic brain tumors was 100 mCi. The dose-limiting toxicity was neurologic toxicity. We are encouraged by the minimal toxicity and survival in this phase I trial. Radiolabeled mAbs may improve the current therapy for brain tumor patients. 相似文献
177.
W Zareba AJ Moss PJ Schwartz GM Vincent JL Robinson SG Priori J Benhorin EH Locati JA Towbin MT Keating MH Lehmann WJ Hall 《Canadian Metallurgical Quarterly》1998,339(14):960-965
BACKGROUND: The congenital long-QT syndrome, caused by mutations in cardiac potassium-channel genes (KVLQT1 at the LQT1 locus and HERG at the LQT2 locus) and the sodium-channel gene (SCN5A at the LQT3 locus), has distinct repolarization patterns on electrocardiography, but it is not known whether the genotype influences the clinical course of the disease. METHODS: We determined the genotypes of 541 of 1378 members of 38 families enrolled in the International Long-QT Syndrome Registry: 112 had mutations at the LQT1 locus, 72 had mutations at the LQT2 locus, and 62 had mutations at the LQT3 locus. We determined the cumulative probability and lethality of cardiac events (syncope, aborted cardiac arrest, or sudden death) occurring from birth through the age of 40 years according to genotype in the 246 gene carriers and in all 1378 members of the families studied. RESULTS: The frequency of cardiac events was higher among subjects with mutations at the LQT1 locus (63 percent) or the LQT2 locus (46 percent) than among subjects with mutations at the LQT3 locus (18 percent) (P<0.001 for the comparison of all three groups). In a multivariate Cox analysis, the genotype and the QT interval corrected for heart rate were significant independent predictors of a first cardiac event. The cumulative mortality through the age of 40 among members of the three groups of families studied was similar; however, the likelihood of dying during a cardiac event was significantly higher (P<0.001) among families with mutations at the LQT3 locus (20 percent) than among those with mutations at the LQT1 locus (4 percent) or the LQT2 locus (4 percent). CONCLUSIONS: The genotype of the long-QT syndrome influences the clinical course. The risk of cardiac events is significantly higher among subjects with mutations at the LQT1 or LQT2 locus than among those with mutations at the LQT3 locus. Although cumulative mortality is similar regardless of the genotype, the percentage of cardiac events that are lethal is significantly higher in families with mutations at the LQT3 locus. 相似文献
178.
The high-pressure Diels-Alder reaction of N-carbomethyoxypyrroles and phenyl vinyl sulfone affords versatile intermediates for the palladium-catalyzed preparation of new epibatidine analogues. Structure-activity relationships of new epibatidine analogues are presented. High affinities of Ki = 0.81 and 2.6 nM for the [3H]-cytisine rat brain nicotinic acetylcholine binding sites were found for the 5-pyrimidinyl and the 5-(2-amino)-pyrimidinyl epibatidine analogues, respectively. 相似文献
179.
Health status measurement in Toxic Oil Syndrome 总被引:1,自引:0,他引:1
A Gómez de la Cámara M Posada de la Paz I Abaitua Borda MT Barainca Oyagüe V Abraira Santos MD Ruiz-Navarro B Terracini 《Canadian Metallurgical Quarterly》1998,51(10):867-873
Toxic Oil Syndrome (TOS) is a previously unreported condition which affected more than 20,000 people in Spain in 1981 and whose natural history is unknown. In 1993-94, a stratified random sample of 1400 survivors was drawn to measure their health status through clinical examination and their self-perception of well-being through the Nottingham Health Profile Questionnaire (NHPQ). Two-thirds of the sample population responded; indirect estimates suggest that selection bias was limited. Clear and intermediate signs of neuropathy were found in one-fifth and one-half of the patients, respectively. One-fourth and one-sixth showed some degree of scleroderma and contractures. All conditions were more frequent in women than in men and in age >50 than in younger ages. Although no concurrent control group was included in the study, prevalences of these conditions are well above expectations and are largely attributable to TOS. NHPQ scores increased with age in both sexes up to age 50, after which they reached a plateau (with values around 48 in men and 62 in women). Scores were associated to the occurrence of peripheral neurological changes, contractures, and scleroderma-like conditions. A multivariate analysis indicated age, sex, and severity of neurological conditions as major determinants of the NHPQ scores. This overall pattern of findings is peculiar to TOS and differs from the typical post-disaster nonspecific syndrome. 相似文献
180.
SA Eisen N Lin MJ Lyons JF Scherrer K Griffith WR True J Goldberg MT Tsuang 《Canadian Metallurgical Quarterly》1998,93(9):1375-1384
BACKGROUND: Pathological gambling is becoming an increasing problem in the United States as the number of legalized gambling establishments grows. To examine vulnerability to pathological gambling, we estimated the familial contributions (i.e. inherited factors and/or experiences shared by twin siblings during childhood) to DSM-III-R pathological gambling symptoms and disorder. METHODS: Data were obtained from a telephone interview performed in 1991-92 utilizing the Diagnostic Interview Schedule Version III-Revised. Interviews were administered to 6718 members of the nationally distributed Vietnam Era Twin Registry of male-male monozygotic and dizygotic twin pairs who served in the military during the Vietnam era. RESULTS: Inherited factors explain between 35% (95% CI: 28%, 42%) and 54% (95% CI: 39%, 67%) of the liability for the five individual symptoms of pathological gambling behavior that could be estimated statistically. In addition, familial factors explain 56% (95% CI: 36%, 71%) of the report of three or more symptoms of pathological gambling and 62% (95% CI: 40%, 79%) of the diagnosis of pathological gambling disorder (four or more symptoms). CONCLUSIONS: Familial factors have an important influence on risk for pathological gambling behavior. The increasing access to legalized gambling is likely to result in a higher prevalence of pathological gambling behavior among individuals who are more vulnerable because of familial factors. 相似文献