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991.
Whole blood concentrations of selenium were determined in 776 dairy cows and calves from 28 farms located in three States (Aragua, Carabobo and Guárico) of the central zone of Venezuela and in Portuguesa State. Selenium levels largely varied according to both the geographic distribution and animals breed. Cattle from Guárico State showed the lowest average concentration (0.21 ppm) and those from Portuguesa the highest one (0.67 ppm). A group of animals from Turén (a District of Portuguesa State) showed the highest average concentration (1.64 ppm, range 1.02 +/- to 3.24 ppm). Concentrations of this magnitude in animals under grazing conditions could be related to high levels of selenium either in the soil or in the pasture. It is concluded that such animals are localized inaseleniferous zone (Turén). It must be noted that Jaffé et al. (op. cit.) found high levels of selenium in sesame seeds (Sesamum indicum) from this area and in blood and urine samples of children from Villa Bruzual, a little town of Turén. The results of this wok significantly differ from those obtained in other countries (of Europe and North America), where animals are managed under conditions very different from those of the tropical areas like Venezuela. The role this factor is discussed. This is the first report on blood levels in large animals of economical importance in Venezuela. 相似文献
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993.
Voluntary muscle involvement in hypertrophic cardiomyopathy. A study of eleven patients 总被引:1,自引:0,他引:1
ER Smith LP Heffernan VE Sangalang LM Vaughan CS Flemington 《Canadian Metallurgical Quarterly》1976,85(5):566-572
Hypertrophic cardiomyopathy is generally considered to be a primary disease of cardiac muscle, although several clinical observations suggest that the pathologic process might be more diffuse. To further examine this possibility, electromyography and voluntary muscle biopsies were done on 11 patients with hypertrophic cardiomyopathy. In 10 of 10 patients electromyography showed reductions in mean potential amplitude and duration, with an increased incidence of short-duration polyphasic deflections (findings traditionally accepted as indicative of a myopathic process). Light and electron microscopic studies of the biopsy material showed abnormalities in eight of 11 patients: four had central core or target fibers, or both, and two of these, plus four others, had subsarcolemmal mitochondrial proliferation with or without abnormal ultrastructure. These findings indicate that hypertrophic cardiomyopathy is only one aspect of a larger disease spectrum, with abnormalities in both voluntary and cardiac muscle. 相似文献
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1. During dehydrocholate administration in the taurine replete dog, the maximum excretory rate of total bile salt (almost entirely dehydrocholate derivative, mostly conjugated) was 3-84 +/- 0-53 (S.D.) mumole/min. kg body wt. (eleven experiments). This was much less than the excretory maximum previously obtained for taurocholate (8-64 +/- 1-31 (S.D.) mumole/min. kg total cholate, mostly conjugated). 2. The superimposition of taurocholate infusion did not cause any significant change in the 'dehydrocholate' maximum but taurocholate itself was excreted into bile at no more than about half its normal maximum. When taurocholate maximum excretion was established first, it was reduced by dehydrocholate administration. In both types of experiment the joint bile salt excretory maximum was of the same order as that of taurocholate alone, provided taurocholate made up at least 40-50% of the total bile salt. 3. When taurocholate administration was stopped, the maximum excretory rate of 'dehydrocholate' rose to values up to 63% above the initially determined excretory maximum; the enhanced 'dehydrocholate' excretory maximum, when calculated for optimal conditions, approached that of actively conjugated vholate, even though the effective 'dehydrocholate' concentration in bile was ten to twenty times the critical micellar concentration of taurocholate. This suggests that the effective bile salt concentration in bile is not an important determinant of the secretory performance of a bile salt. 4. To explain findings (2) and (3) it is necessary to postulate that taurocholate has both a facilitatory and an inhibitory action on 'dehydrocholate' excretion. The facilitatory action, which persists after taurocholate has left the animal, may consist either of an increase in the maximum rate at which modification of dehydrocholate takes place within the liver cell, or an increase in the number of functioning 'carriers' for 'dehydrocholate' transfer. The data suggest that the inhibitory effect is due to the competitive interaction that also appears to exist between the two bile salts. 5. The increase in bile flow rate per unit increase in 'dehydrocholate' excretion (15 ml./m-mole) was about twice that obtained for taurocholate. There was no significant formation of micellar aggregates during 'dehydrocholate' excretion, as judged from the total electrolyte concentration of bile and its osmalality. 6. During the excretion of 'dehydrocholate'-taurocholate mixtures (approximately 1:1) at submaximal rates the associated bile flow rate was not less than the sum of the separate components, thus suggesting that 'dehydrocholate' was not being incorporated in taurocholate mixed micelles. 相似文献
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JL Boxerman TJ Mosher ER McVeigh E Atalar JA Lima DA Bluemke 《Canadian Metallurgical Quarterly》1998,18(3):543-564
A "one-stop shop" for evaluating cardiac disease with magnetic resonance (MR) imaging is progressing toward clinical reality and promises to have a major effect on the care of patients with cardiac disease. T1-weighted conventional spin-echo imaging gated to the cardiac cycle yields good anatomic detail but requires long imaging times and provides only static images of a single cardiac phase. Fast MR imaging with electrocardiographically (ECG) gated, low-flip-angle, segmented k-space gradient-recalled-echo (GRE) sequences provides excellent image quality with sufficiently high temporal resolution to "freeze" cardiac motion. Segmented k-space sequences improve on standard ECG-gated GRE sequences by allowing many cardiac phases, or frames of a cine sequence, to be imaged in a single breath hold with prospective cardiac gating. As commercial implementations of segmented k-space imaging become more widely available, the applications of this technique are expanding from research protocols to include many clinical applications in the heart and great vessels. Such applications include evaluation of vascular anatomy (coronary angiography, aortic disease, aberrant vessels, vascular access), cardiac anatomy (congenital anomalies, right ventricular dysplasia, constrictive pericarditis, valvular function), myocardial perfusion, and myocardial wall motion. 相似文献
1000.
In late 1997, the authors conducted a national survey of communities of interest about the importance and clarity of 44 accreditation standards applied to teaching, learning, and evaluation in medical schools by the Liaison Committee on Medical Education (LCME). Questionnaires were mailed to deans and educational administrators at U.S. medical schools; current LCME members and surveyors and those who had served during the preceding five years; a random selection of residency program directors drawn from both general practice and speciality disciplines; sample groups of medical students and residents; and a cohort of practicing physicians not affiliated with academic medical institutions. Altogether 1,659 questionnaires were mailed, and 701 responses were received (42%). The recipients were asked to use a five-point Likert scale to rate each of the 44 standards both for its perceived importance as an indicator of the quality of undergraduate medical education and for the clarity with which the standard's intent was conveyed. Although the mean ratings of importance all fell in the "moderately important" and "highly important" areas across the respondent groups, the ratings divided into three groups, semantically and statistically. At the high end for importance are standards dealing with fundamental qualities of students, instruction, and the structuring of resources. At the low end of the importance scale are standards dealing largely with matters of process. The ratings for clarity were systematically lower than the ratings for importance, and in some cases the rating for clarity were even more widely discrepant with the ratings for importance. Individual comments by respondents about certain standards were critical of their complicated construction and of confusion about their meaning and measures of compliance. One or more of these hallmarks--being rated of lower importance or clarity, and being the target of criticism by survey respondents--distinguished most of the standards that earlier study had shown are often neglected by surveyors. The predictive validity of each of a number of standards was examined by testing the association between the standard (or its derivative) and outcomes expressed in annual student and school questionnaires and compiled in databases of the Association of American Medical Colleges and the American Medical Association. The result was a mixed bag, confounded by the absence of specific dimensions of many accreditation standards (independent variables) and the lack of discriminating measures of outcome (dependent variables). Nevertheless, the LCME's accreditation standards are believed to be important by those most affected by them. And beyond validating that medical accreditation is guided by relevant standards for teaching, learning, and evaluation, the results of this study point to ways by which the process can be made more precise and useful. 相似文献