全文获取类型
收费全文 | 1473篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 11篇 |
金属工艺 | 3篇 |
机械仪表 | 1篇 |
建筑科学 | 2篇 |
能源动力 | 2篇 |
轻工业 | 3篇 |
水利工程 | 6篇 |
无线电 | 1篇 |
一般工业技术 | 7篇 |
冶金工业 | 1429篇 |
原子能技术 | 4篇 |
自动化技术 | 6篇 |
出版年
2023年 | 1篇 |
2018年 | 4篇 |
2017年 | 1篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 6篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1999年 | 44篇 |
1998年 | 474篇 |
1997年 | 264篇 |
1996年 | 173篇 |
1995年 | 88篇 |
1994年 | 73篇 |
1993年 | 88篇 |
1992年 | 9篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 22篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 1篇 |
1978年 | 4篇 |
1977年 | 23篇 |
1976年 | 80篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1476条查询结果,搜索用时 328 毫秒
991.
Human secretory leukocyte protease inhibitor (SLPI) is a predominant physiologic inhibitor of elastase and cathepsin G, proinflammatory serine proteases released by activated neutrophils. In order to fully evaluate the potential pharmacologic efficacy of human SLPI in animal models of inflammation, it is critical to know the potency of the inhibitor for corresponding proteases from the species of interest. In this report, we compare the inhibitory activity of human and murine SLPI against elastase and cathepsin G from both species. Human and murine neutrophil elastase and cathepsin G display comparable Km values for their specific peptide substrates. Murine SLPI inhibits murine neutrophil elastase and cathepsin G with Ki values of 5 and 0.12 nM, respectively, while human SLPI inhibits the both murine serine proteases with Ki's of 0.02 nM. In contrast, murine SLPI inhibits human neutrophil elastase and cathepsin G with Ki values of 1.4 and 90 nM, respectively, while human SLPI inhibits the proteases with Ki's of 0.3 and 10 nM, respectively. These results demonstrate species-specific variations in the protease inhibitory activities of SLPI. Such variations should be considered in the evaluation of the activity of human SLPI in murine pharmacologic models. 相似文献
992.
CD Steward SA Stocker JM Swenson CM O'Hara JR Edwards RP Gaynes JE McGowan FC Tenover 《Canadian Metallurgical Quarterly》1999,37(3):544-547
Fluoroquinolone resistance appears to be increasing in many species of bacteria, particularly in those causing nosocomial infections. However, the accuracy of some antimicrobial susceptibility testing methods for detecting fluoroquinolone resistance remains uncertain. Therefore, we compared the accuracy of the results of agar dilution, disk diffusion, MicroScan Walk Away Neg Combo 15 conventional panels, and Vitek GNS-F7 cards to the accuracy of the results of the broth microdilution reference method for detection of ciprofloxacin and ofloxacin resistance in 195 clinical isolates of the family Enterobacteriaceae collected from six U.S. hospitals for a national surveillance project (Project ICARE [Intensive Care Antimicrobial Resistance Epidemiology]). For ciprofloxacin, very major error rates were 0% (disk diffusion and MicroScan), 0.9% (agar dilution), and 2.7% (Vitek), while major error rates ranged from 0% (agar dilution) to 3.7% (MicroScan and Vitek). Minor error rates ranged from 12.3% (agar dilution) to 20.5% (MicroScan). For ofloxacin, no very major errors were observed, and major errors were noted only with MicroScan (3.7% major error rate). Minor error rates ranged from 8.2% (agar dilution) to 18.5% (Vitek). Minor errors for all methods were substantially reduced when results with MICs within +/-1 dilution of the broth microdilution reference MIC were excluded from analysis. However, the high number of minor errors by all test systems remains a concern. 相似文献
993.
The three-dimensional structure of omega-conotoxin MVIID has been determined in aqueous solution by two-dimensional 1H NMR techniques. A total of 267 relevant upper-bound distance restraints were used to obtain a family of convergent structures using molecular dynamics methods. A standard simulated annealing protocol using the XPLOR program included in ARIA provided a total of 18 final structures. The averaged RMSD between these structures and the mean atomic coordinates was 0.8 +/- 0.3 A for the backbone atoms. The highest mobility was observed in the segments between residues 10 to 13, comprising Tyr 13, one of the residues shown to be important for binding of omega-conotoxin GVIA and MVIIA to N-type calcium channels. The three-dimensional structure is stabilised by the three disulfide bonds and includes a short antiparallel beta-strand between residues 5-8, 23-25 and 19-21. The folding for this non-N-type calcium channel blocker is similar to that previously calculated for omega-conotoxins GVIA, MVIIA and MVIIC. This suggests the disulfide bond pattern fixes the structure. The reported three-dimensional information can be used to advantage in order to highlight the structural parameters involved in discrimination among calcium channel subtypes. 相似文献
994.
995.
Shelley Williams Krista Witherspoon Peter Kavsak Cyndi Patterson Jacqueline McBlain 《Revue canadienne de la pratique et de la recherche en diététique》2006,67(4):185-190
In 1995, Oshawa General Hospital (now Lakeridge Health Corporation, Oshawa site) developed an interdisciplinary feeding and swallowing clinic to serve children with feeding problems. After four years, a retrospective chart review of 104 subjects was completed to assess the performance of the clinic, which consists of a pediatrician, a speech-language pathologist (S-LP), an occupational therapist (OT), and a registered dietitian (RD). Goals were set at the initial and follow-up visits. These goals were individualized according to client needs and were related to improvements in growth and/or feeding abilities. During this period, 176 of 232, or 75.9% (70-81, 95% confidence interval), of the initial goals were attained by the first follow-up visit. Progress in the clinic, as measured by the number of goals achieved by the first follow-up visit, was further analyzed according to the patient age group/category (i.e., infant, toddler, and child) and by the health care professional (i.e., S-LP, OT, and RD) to ascertain and compare success rates in these groups and professionals. The overall success rates in the patient age groups (p=0.07) and among the different professionals (p=0.92) were not significantly different. In short, the interdisciplinary team approach proved successful in treating feeding problems in patients referred to the clinic. 相似文献
996.
997.
RA Taylor PH Marshall RD Dunlap CD Gable PS Sizer 《Canadian Metallurgical Quarterly》1998,28(2):81-87
OBJECTIVES: To estimate the number of breast cancer deaths induced by low dose radiation in breast cancer screening programmes compared with numbers prevented. METHODS: A computer simulation model on the natural history of breast cancer was combined with a model from BEIR-V on induced breast cancer mortality from low levels of radiation. The improvement in prognosis resulting from screening was based on the results of the Swedish overview of the randomised screening trials for breast cancer and the performance of screening in the Netherlands. Different scenarios (ages and intervals) were used to explore the objectives. Sensitivity analyses were carried out for latency period, dose of mammography, sensitivity of the screening test, early detection by screening of induced breast tumours, and new 1996 risk estimates by Howe and McLaughlin. RESULTS: For a screening programme, age group 50-69, two year interval, 2 mGy per view, the balance between the number of deaths induced versus those prevented was favourable: 1:242. When screening is expanded to the age group 40-49 with a one or two year interval the results may be less favourable, that is, 1:66 and 1:97. According to these scenarios and with the Dutch scenario as reference, one breast cancer death from radiation may be expected to occur to save eight extra deaths from breast cancer. If screening was equally effective in young women as in women aged 50-69, the marginal value was 1:+/- 30. Assuming detection of induced cancers by screening could influence the ratios by about 30%, but did not substantially change the conclusions. The new risk estimates by Howe and McLaughlin resulted in five times to eight times favourable ratios breast cancer deaths induced to prevented. Besides age group of screening, dose of mammography is the other determinant of risk. CONCLUSIONS: For screening under the age of 50, the balance between the number of breast cancer deaths prevented by screening compared with the number induced by radiation seem less favourable. Credibility intervals were however wide, because of many uncertainties of radiation risk at very low doses. 相似文献
998.
999.
1000.
OBJECTIVE: To develop a method for the detection of bilateral Horner's syndrome in patients with bilateral interruption of the cervical sympathetic pathway or widespread autonomic neuropathy. METHODS: Darkness pupil diameters and redilatation times during light reflexes have been recorded with infrared TV pupillometry in 65 healthy subjects, 47 patients with unilateral Horner's syndrome, and 20 patients with bilateral Horner's syndrome. The aetiologies of the last group were diabetic autonomic neuropathy (three cases), amyloidosis (four), pure autonomic failure (PAF) (four), dopamine-beta-hydroxylase deficiency (two), and one case each of hereditary sensory and autonomic neuropathy (HSAN) type III, carcinomatous sympathetic neuropathy, familial dysautonomia, multiple system atrophy, Anderson-Fabry disease, and anterior spinal artery thrombosis at C5,6 and one had had bilateral cervical sympathectomies. RESULTS: Darkness diameters on the affected side were below normal in 12 patients with unilateral Horner's syndrome, the measurement yielding only 26% sensitivity for detection of the condition. By contrast, the time taken to reach three quarter recovery in the light reflex (T3/4) was abnormally prolonged (redilatation lag) in 33 of the same eyes. The measurement yielded 70% sensitivity and 95% specificity for detection of the condition. In 20 cases, diagnosed on clinical grounds as having bilateral Horner's syndrome of various aetiologies, pupil diameters were abnormally small on both sides in five and on one side in three patients. Fourteen of these patients had significant redilatation lag in both eyes, five patients in one eye, and one patient had it in neither eye. Measurement of redilatation lag was therefore a more sensitive diagnostic test than pupil diameter in both unilateral and bilateral Horner's syndrome. CONCLUSIONS: Provided that the pupils are not tonic, bilateral Horner's syndrome can be diagnosed on the basis of redilatation lag. It occurs clinically in some generalised autonomic neuropathies and with interruption of the local sympathetic nerve supplies to the two eyes. 相似文献