全文获取类型
收费全文 | 152篇 |
免费 | 0篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 153篇 |
出版年
2021年 | 2篇 |
2016年 | 1篇 |
2013年 | 37篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 8篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有153条查询结果,搜索用时 46 毫秒
21.
Jacobson Joseph L.; Jacobson Sandra W.; Padgett Robert J.; Brumitt Gail A.; Billings Robin L. 《Canadian Metallurgical Quarterly》1992,28(2):297
Assesses 4-yr-old children exposed prenatally to polychlorinated biphenyls (PCBs; an environmental toxin) on 3 tasks: 2 designed to evaluate cognitive processing efficiency and 1 to evaluate sustained attention. When compared with standardized IQ tests, these tasks provided greater specificity in identifying cognitive deficits. Adapted for 4-yr-old children in the present study, these paradigms demonstrated moderate levels of test–retest reliability. Prenatal exposure to PCBs was associated with less efficient visual discrimination processing and more errors in short-term memory scanning but not with sustained attention. Although much larger quantities of these contaminants are transferred postnatally via breastfeeding than prenatally across the placenta, postnatal exposure was unrelated to cognitive performance. The data link intrauterine PCB exposure to 2 dimensions of cognitive functioning fundamental to learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
22.
The occurrence of Rocky Mountain spotted fever, human monocytotropic ehrlichiosis, tularemia, tick-borne relapsing fever, and a southern erythema migrans-like illness (Lyme/Lyme-like disease) is determined by the geographic distribution and seasonal activity of the particular vector tick(s). The flulike signs and symptoms early in the course of spotted fever rickettsiosis, ehrlichiosis, tularemia, and relapsing fever are nonspecific and do not readily suggest a particular diagnosis. Laboratory diagnosis, particularly during the acute stage of illness, often is elusive. Empiric treatment with doxycycline can be lifesaving for Rocky Mountain spotted fever and ehrlichiosis. This article provides insight into the significance of each of these tick-transmitted diseases in Texas. 相似文献
23.
24.
DH Walker HM Feng S Ladner AN Billings SR Zaki DJ Wear B Hightower 《Canadian Metallurgical Quarterly》1997,10(10):1038-1042
A monoclonal antibody directed against an epitope on the lipopolysaccharide of typhus-group rickettsiae was developed for the purpose of detecting this heat-stable, proteinase-resistant antigen in formalin-fixed, paraffin-embedded tissues. Rickettsia prowazekii organisms were identified in endothelium and macrophages in sections of the brains of three Egyptian men who died of epidemic louse-borne typhus in Cairo during World War II and in the brain from a recent case of typhus fever acquired in Burundi. R. typhi organisms were identified in endothelial cells from a fatal case of murine typhus and in experimentally infected mice. This approach is applicable not only to the study of archival tissues and experimental animal models but also could be used to establish a timely diagnosis of typhus-group rickettsiosis by immunohistochemical examination of cutaneous biopsies of rash lesions during the acute stage of illness. 相似文献
25.
OBJECTIVE: To describe the status of palliative care education in the undergraduate medical curriculum and to offer recommendations for improvement. DATA SOURCES: Review of literature on palliative care and of recently submitted grants on medical education for end-of-life care. STUDY SELECTION: English-language reports of educational programs targeted toward medical students were examined, as well as surveys of medical schools. DATA EXTRACTION: Studies were reviewed by the authors to assess the quality of the educational program, evaluation methodology, and conclusions. From over 9000 citations on palliative care and related topics that were retrieved from MEDLINE searches from 1980 through 1995, and from reviewing 14 palliative care journals published from 1985 through 1996, 310 articles were identified that addressed medical education for end-of-life care, and 180 were carefully examined. DATA SYNTHESIS: While nearly all medical schools offer some formal teaching about end-of-life care, there is considerable evidence that current training is inadequate, most strikingly in the clinical years. Teaching about palliative care is received favorably by students, positively influences student attitudes, and enhances communication skills. However, curricular offerings are not well integrated; the major teaching format is the lecture; formal teaching is predominantly preclinical; clinical experiences are mostly elective; there is little attention to home care, hospice, and nursing home care; role models are few; and students are not encouraged to examine their personal reactions to these clinical experiences. CONCLUSIONS: The increasing attention to palliative care education has created major opportunities for improving education about care at the end of life. Educational programs should be rigorously evaluated to identify best educational practices. 相似文献
26.
E. A. Roberts P. M. Billings T. L. Payne J. V. Richerson C. W. Berisford R. L. Hedden L. J. Edson 《Journal of chemical ecology》1982,8(3):641-652
The response ofDendroctonus frontalis to an attractant mixture (frontalin,trans-verbenol, and loblolly pine turpentine) was measured in the laboratory over a four-year period. Beetle response was highest in late winter and early spring, and lowest in midsummer and early fall. Males consistently responded higher than females. Female beetles displayed significantly higher responses in early morning and late afternoon than in the middle of the day. Analysis of beetle pronotal width and fat content revealed a high degree of correlation between these two parameters in female beetles, but there was no correlation of response with either fat content or pronotal width for either sex. There was no evident relationship between mean monthly beetle response and total amounts of frontalin andtrans-veibenol found in hindgut extracts. Daily temperature in months both during which beetles were bioassayed and immediately prior to bioassay was highly correlated to response to the attractant.Texas Agricultural Experiment Station Paper Number 16652. This research was supported by McIntire-Stennis Project 1525, and the U.S. Department of Agriculture-sponsored program entitled The Expanded Southern Pine Beetle Research and Applications Program through TAES-SEA-CR Grant 904-15-4. The findings, opinions, and recommendations expressed herein are those of the authors and not necessarily those of the U.S. Department of Agriculture. All programs and information of the Texas Agricultural Experiment Station are available to everyone without regard to race, color, religion, sex, age, or national origin. 相似文献
27.
The paper highlights the requirement for a comprehensive program suite to facilitate data analysis. An attempt is made to integrate all the normal routines encountered in a scientific data processing environment into one package. Addition of new algorithms to the package is simplified by avoiding duplication of data handling and display segments, and by the chaining of existing options. The applications of the suite are illustrated using field derived data. 相似文献
28.
29.
Plasma brain natriuretic peptide in assessment of acute dyspnoea 总被引:1,自引:0,他引:1
M Davis E Espiner G Richards J Billings I Town A Neill C Drennan M Richards J Turner T Yandle 《Canadian Metallurgical Quarterly》1994,343(8895):440-444
Recognition of heart failure (HF) may be difficult in patients presenting with acute dyspnoea, particularly in the presence of chronic airways obstruction. Since increased secretion of the cardiac hormones atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) occurs early in the course of HF, we have assessed the value of measuring these hormones in plasma in the diagnosis of suspected HF in 52 elderly patients presenting with acute dyspnoea, and compared values with left-ventricular ejection fraction (LVEF), a standard measure of left-ventricular function, by radionuclide angiography. Patients were enrolled prospectively. On the basis of clinical findings, conventional tests, and response to specific treatment, 20 of the 52 patients were classified as having primary lung disorder (PLD), 12 as HF alone, and 20 as HF with underlying PLD (HF/PLD). Compared with findings in PLD patients, LVEF was significantly depressed in HF and HF/PLD patients (p < 0.001), whereas both plasma ANP and BNP were significantly increased (p < 0.001). Admission plasma BNP concentration more accurately reflected the final diagnosis of HF (93% sensitivity and 90% specificity when BNP > or = 22 pmol/L) than LVEF or plasma ANP concentration. When all patients were considered together, there were strong negative correlations between LVEF and log BNP (r = -0.7, p < 0.001) and log ANP (r = -0.59, p < 0.001). Our finding that plasma BNP is raised in dyspnoeic patients with HF but not in acutely breathless patients with PLD, suggests that rapid BNP assays may assist in the diagnosis of patients with acute dyspnoea. 相似文献
30.
Efficient cw end-pumped, end-cooled Nd:YVO(4) diode-pumped laser 总被引:2,自引:0,他引:2
Using a novel end-pumped, end-cooled geometry, we demonstrated a Nd:YVO(4) cw laser that produces close to 2 W of single-mode output when pumped by a high-brightness 100-mum-core diode fiber source. An optical-optical conversion efficiency of 49% was obtained. Beam quality was found to be nearly diffraction-limited (M(2) = 1.08) and independent of pumping power. 相似文献