首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   177篇
  免费   0篇
轻工业   1篇
冶金工业   176篇
  2018年   1篇
  1999年   2篇
  1998年   54篇
  1997年   35篇
  1996年   15篇
  1995年   14篇
  1994年   9篇
  1993年   9篇
  1992年   1篇
  1990年   3篇
  1989年   2篇
  1988年   4篇
  1987年   3篇
  1986年   3篇
  1985年   2篇
  1983年   2篇
  1981年   2篇
  1980年   3篇
  1977年   2篇
  1976年   10篇
  1955年   1篇
排序方式: 共有177条查询结果,搜索用时 0 毫秒
111.
Virus-associated haemophagocytic syndrome (VAHS) is a rare disease characterized by fever, splenomegaly, cytopenia and histiocytic proliferation with haemophagocytosis in the reticuloendothelial system. The clinical course of VAHS can be dramatic and the prognosis is often poor. The pathogenesis of VAHS is not well understood. Many believe that viral infection provokes an abnormal immune response in predisposed individuals leading to hyperactivation of Th1 helper cells, macrophage proliferation and secretion of large amounts of cytokines. The resultant hypercytokinaemia may be responsible for the clinical and biochemical manifestations of VAHS. In this article the clinical features, presumed pathogenesis, diagnostic criteria and treatment of VAHS are discussed.  相似文献   
112.
We have developed an algorithmic method for automatic determination of stimulation thresholds in both cardiac chambers in patients with intact atrioventricular (AV) conduction. The algorithm utilizes ventricular sensing, may be used with any type of pacing leads, and may be downloaded via telemetry links into already implanted dual-chamber Thera pacemakers. Thresholds are determined with 0.5 V amplitude and 0.06 ms pulse-width resolution in unipolar, bipolar, or both lead configurations, with a programmable sampling interval from 2 minutes to 48 hours. Measured values are stored in the pacemaker memory for later retrieval and do not influence permanent output settings. The algorithm was intended to gather information on continuous behavior of stimulation thresholds, which is important in the formation of strategies for programming pacemaker outputs. Clinical performance of the algorithm was evaluated in eight patients who received bipolar tined steroid-eluting leads and were observed for a mean of 5.1 months. Patient safety was not compromised by the algorithm, except for the possibility of pacing during the physiologic refractory period. Methods for discrimination of incorrect data points were developed and incorrect values were discarded. Fine resolution threshold measurements collected during this study indicated that: (1) there were great differences in magnitude of threshold peaking in different patients; (2) the initial intensive threshold peaking was usually followed by another less intensive but longer-lasting wave of threshold peaking; (3) the pattern of tissue reaction in the atrium appeared different from that in the ventricle; and (4) threshold peaking in the bipolar lead configuration was greater than in the unipolar configuration. The algorithm proved to be useful in studying ambulatory thresholds.  相似文献   
113.
PURPOSE: Chronic prostatitis is a common histopathological finding in prostatectomized patients. A possible interrelationship between the presence of leukocyte exudate and the extent of the hyperplastic lesions has been suggested. The aim of the present study was to analyze the effect of the immunomodulator compounds, Complete Freund Adjuvant (CFA) and cyclosporin A (CsA), administered alone or together with citral on the induction and extent of rat prostatic hyperplasia. MATERIALS AND METHODS: Adolescent Wistar rats (42 days old) were given citral alone or combined with CFA or CsA for one month. Semiquantitative analysis of the extent of the hyperplastic lesions was made with the histoscore protocol. RESULTS: CsA did not induce hyperplastic changes or abolish the ability of citral to promote hyperplastic changes or to affect the extent of the lymphocytic exudate in the stroma. CFA itself, however, had a proliferative action on the prostatic epithelium, and it augmented the hyperplastic changes induced by citral and even induced atypical transformations of the acinar epithelium. CONCLUSIONS: Immunoinflammatory stimulators might play a role in the prostatic epithelial cell growth and proliferation processes, most probably by modulation of the cytokine system.  相似文献   
114.
115.
Intracrevicular antimicrobial therapy is consistent with the site-specific nature of periodontitis. Considerable research has focused on the use of nonresorbable fibers. However, a bioerodible system is desirable. The purpose of this study was to assess tetracycline release and safety following a single application of a syringable 35% tetracycline hydrochloride in a lactic-glycolic acid gel. 31 generally healthy adult volunteers (mean age = 59 years) were enrolled in and completed this randomized, double-blind eight day study. 2, 6-10 mm non-adjacent interproximal pockets that bled on pocket probing were chosen as experimental sites in each subject. I experimental site and the surrounding gingival crevice received small particle size tetracycline in gel while the other site received larger particle size tetracycline in gel. Gingival crevicular fluid (GCF) was collected prior to treatment and 15 min, 1, 2, 3, 4 and 8 days post-treatment. GCF tetracyline concentrations were determined by agar diffusion bioassay and GCF volume measurements. 61% and 71% of sites had > or = 100 micrograms/ml tetracycline 3 days following application of large (mean concentration = 430 +/- 92 micrograms/ml) and small particle gels (mean concentration = 418 +/- 70 micrograms/ml), respectively. 37% and 55% of sites had measurable tetracycline 8 days after placement of large (mean concentration = 86 +/- 31 micrograms/ml) and small particle gels (mean concentration = 293 +/- 79 micrograms/ml), respectively. The most common adverse event was "bitter taste" (10% of subjects). Based upon the reduction in probing depths and % of sites bleeding on probing at 8 days relative to pretreatment, and the absence of any serious adverse events, it is concluded that these bioerodible gels are safe, and since the bacteriostatic range for most putative periodontopathogens is in the 2-10 micrograms/ml range, the tetracycline levels observed at days 3 and 8 likely represent significant antimicrobial efficacy.  相似文献   
116.
The prevalence of filariae in wild raccoons trapped in southeast Georgia was determined. Examination of blood samples revealed that 74 of 113 raccoons (66%) trapped in 6 southeastern Georgia counties were infected. Seventy-three of these raccoons (65%) were infected with Mansonella llewellyni and this parasite was observed in raccoons from every location examined. Dirofilaria tenuis was found in 22 raccoons (20%) and was observed in only 3 of the 6 counties surveyed. An adult specimen of Acanthocheilonema procyonis was found in the subcutaneous tissues of 1 of 5 necropsied raccoons. This is the first record of filariae in raccoons from Georgia. In addition, Dirofilaria-like larvae were found in Aedes taeniorhyncus mosquitoes collected in Liberty County.  相似文献   
117.
118.
Minitracheostomy is a commonly performed procedure usually carried out by junior medical staff. Though there are few problems associated with the technique of minitracheostomy, bleeding is often encountered. We now present a brief case report demonstrating the problems associated with bleeding. We also outline an alteration in insertion technique with the 'Minitrach' designed to diminish the risks of serious bleeding, and report on our results with this technical modification.  相似文献   
119.
To establish the value of diagnostic ultrasound (sonar) in the diagnosis of bilitary tract disease, 140 patients were scanned and also had a plain film of the biliary tract. Of these, 105 had contrast radiography and 123 were subjected to laparotomy. The results obtained suggest that in the absence of jaundice, sonar compares well with oral cholecystography in demonstrating the gallbladder, but is not as good as intravenous cholangiography in showing the duct system. In the presence of jaundice, however, sonar is considered the imaging investigation of choice.  相似文献   
120.
One-week-old wood ducks were fed cadmium in diets containing 18 or 30% protein for a period of three months. Seven drakes from each group were sacrificed, and blood, brain, muscle, kidney, liver, and wing feather tissues were collected and analyzed for cadmium. Highest cadmium concentrations were found in the kidney, liver, and feather tissues; blood, muscle, and brain cadmium residue levels were undetectable. Except in the kidney tissue, protein level of the diet did not affect cadmium residue levels. For birds that were changed to a cadmium-free, high-protein ration at 13 weeks of age, regression analysis indicated a significant decrease in cadmium residue levels for the kidney tissue only. Growth, as measured by bodyweight at 13 weeks of age, was not affected by the various cadmium treatment levels. Histopathological examination revealed lesions in the kidney tissues of the 100 ppm cadmium treatment groups, which were more severe in those birds receiving the 18% protein diet. Vacuolation of the pancreatic acinar cells was observed in all groups, but tended to occur more frequently in the higher cadmium level groups.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号