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   943篇
  免费   0篇
电工技术   1篇
综合类   1篇
化学工业   5篇
建筑科学   12篇
矿业工程   2篇
轻工业   5篇
水利工程   1篇
无线电   1篇
一般工业技术   6篇
冶金工业   907篇
自动化技术   2篇
  2016年   1篇
  2013年   5篇
  2011年   1篇
  2010年   4篇
  2008年   1篇
  2006年   1篇
  2005年   3篇
  2004年   2篇
  2003年   2篇
  2002年   1篇
  2001年   1篇
  2000年   2篇
  1999年   25篇
  1998年   286篇
  1997年   164篇
  1996年   109篇
  1995年   50篇
  1994年   67篇
  1993年   49篇
  1992年   10篇
  1991年   14篇
  1990年   7篇
  1989年   8篇
  1988年   4篇
  1987年   6篇
  1986年   7篇
  1985年   6篇
  1983年   3篇
  1982年   3篇
  1981年   7篇
  1980年   12篇
  1978年   1篇
  1977年   29篇
  1976年   48篇
  1972年   2篇
  1971年   1篇
  1969年   1篇
排序方式: 共有943条查询结果,搜索用时 15 毫秒
81.
Benign paroxysmal positional vertigo can be succesfully treated by means of the Epley manoeuvre and vibration. This is a simple, non-invasive and economic procedure for this group of patients, who are greatly affected by vertigo in their daily life and therefore have many sick days.  相似文献   
82.
BACKGROUND: Chemical peels have become an increasingly popular method to treat a myriad of benign skin disorders. Individually, glycolic acid (GA) and 5-fluorouracil (5-FU) have been proven efficacious in the treatment of actinically damaged skin. However, to our knowledge the literature lacks a study examining the synergistic effects of these two agents in the treatment of actinic keratoses (AKs) and solar damage. OBJECTIVE: The aim of the study was to determine if a combination of 5-FU and 70% GA, when delivered in pulse doses, would have greater efficacy than using GA alone in destroying precancerous AKs and improving the cosmetic appearance of the skin. METHODS: A prospective randomized controlled study was designed with 18 subjects who had clinically apparent facial AKs. Each patient was treated with the combination of 5-FU and GA to one half of the face, while GA alone was applied to the other half, in a randomized fashion. A before-treatment count of the number of AKs present on each half of the face was recorded and pretreatment photographs were taken. The solutions were applied weekly to all patients for an 8-week period. A posttreatment count of AKs on each half of the face along with posttreatment photographs followed at 6 months. RESULTS: The combination of 5-FU and GA cleared 91.94% of AKs at a 6-month follow-up period as compared with 19.67% clearing by GA alone. There were no significant side effects reported with the combination peel. CONCLUSION: The fluor-hydroxy pulse peel applied in a pulse dose regimen not only provides cosmetic improvement, but more importantly, has a therapeutic effect on ablating premalignant AKs. This therapeutic effect occurs without the usual morbidity associated with using 5-FU alone in a nonpulsed dosage. Additionally, it is evident that the superficial peeling induced by alpha hydroxy acids may improve cosmesis of actinically damaged skin, but the GA alone cannot destroy a significant number of AKs.  相似文献   
83.
84.
Thymoma in dogs: 23 cases (1980-1991)   总被引:1,自引:0,他引:1  
OBJECTIVE: To assess the efficacy of misoprostol for the treatment of chronic erosive gastritis and associated symptoms. METHODS: We performed a double-blind controlled trial, administering 200-micrograms misoprostol tablets or placebo twice daily for 2 months to 48 patients with symptomatic chronic erosive gastritis. Symptomatology was assessed by means of a standard questionnaire at the beginning and at the end of the study, as well as endoscopic and histologic changes of the gastric mucosa. RESULTS: At the end of the treatment period, a significant reduction in symptom score was observed in misoprostol-treated (from 86.6 +/- 66.2 to 17.6 +/- 18.2, p < 0.001) but not in placebo-treated patients. Endoscopic score was significantly reduced at the end of the treatment period in the misoprostol group, compared with that of the placebo group (p < 0.05). A significant reduction in the activity of histologic gastritis was observed only in patients on misoprostol. The prevalence of gastric colonization by Helicobacter pylori was rather low (30%), and no effect of treatment was observed. CONCLUSIONS: Patients with symptomatic chronic erosive gastritis seem to profit from treatment with misoprostol: the treatment with misoprostol, but not with placebo, was effective in significantly reducing the extent of symptoms. Such an improvement was associated with a substantial improvement in the endoscopic and histologic appearance of the gastric mucosa.  相似文献   
85.
Phorbol ester treatment of MCF-7 cells led to the tyrosine phosphorylation and activation of PKC delta. However, through Western blot analysis and in vitro immunecomplex kinase assays, we detected a differential localization of tyrosine-phosphorylated PKC delta and catalytically active PKC delta. Catalytically active PKC delta was concentrated in Triton X-100 solubilized-membrane fractions while tyrosine-phosphorylated PKC delta was localized to the cytosol fraction. Phorbol ester treatment of MCF-7 cells stimulated both the time-dependent in vivo association of Src with PKC delta, evidenced in Src immunoprecipitates by the co-immunoprecipitation of PKC delta, and activation of Src, evidenced in Src immunoprecipitates as an increase in reactivity with a Src antibody (clone 28) reactive only with active Src (dephosphorylated on residue 530) and in Src and PKC delta immunoprecipitates by an increase in Src kinase activity. While our data are consistent with reports in the literature showing the activator/stimulus-dependent tyrosine phosphorylation of PKC delta, our data show that the tyrosine phosphorylation of PKC delta is not essential for kinase activity. These results are the first to demonstrate an in vivo association between PKC delta and active Src in the absence of over-expression of either PKC delta or Src, and support the association of Src and PKC delta towards a physiological function.  相似文献   
86.
87.
OBJECTIVES: To determine the prevalence of the pathogenic strain of Neisseria meningitidis in contacts of patients with meningococcal disease, and to determine which contact groups are likely to be carriers and warrant chemoprophylaxis. DESIGN: Population based study. SETTING: Norwegian county of Telemark. SUBJECTS: 1535 primary contacts of 48 patients with meningococcal disease, and 78 secondary contacts. INTERVENTIONS: Carriers of the pathogenic strain were treated with rifampicin. All household members and kissing contacts under 15 years of age were treated with oral penicillin. Contacts were taught to recognise the symptoms of meningococcal disease. RESULTS: In 27 of 48 cases investigated, contacts carrying the pathogenic strain of N meningitidis were found. A total of 42 such contacts were identified. Contacts were stratified into three classes according to the assumed closeness of contact with patients. In class 1 (household members and kissing contacts) the prevalence of the pathogenic strain was 12.4% (95% confidence interval 5.5% to 19.3%). In classes 2 and 3 the prevalence was 1.9% (0.9% to 3.4%) and 1.6% (0.14% to 3.1%). CONCLUSIONS: There is a high rate of carriage of the pathogenic strain of N meningitidis in patients' household members and kissing contacts, and this supports the practice of giving chemoprophylaxis to these contacts. The prevalence of carriage among other contacts is 2-3 times that found in the general population (0.7%); the benefits of chemoprophylaxis to these contacts may be marginal.  相似文献   
88.
The AMP-activated protein kinase is a heterotrimeric enzyme, important in cellular adaptation to the stress of nutrient starvation, hypoxia, increased ATP utilization, or heat shock. This mammalian enzyme is composed of a catalytic alpha subunit and noncatalytic beta and gamma subunits and is a member of a larger protein kinase family that includes the SNF1 kinase of Saccharomyces cerevisiae. In the present study, we have identified by truncation and site-directed mutagenesis several functional domains of the alpha1 catalytic subunit, which modulate its activity, subunit association, and protein turnover. C-terminal truncation of the 548-amino acid (aa) wild-type alpha1 protein to aa 312 or 392 abolishes the binding of the beta/gamma subunits and dramatically increases protein expression. The full-length wild-type alpha1 subunit is only minimally active in the absence of co-expressed beta/gamma, and alpha1(1-392) likewise has little activity. Further truncation to aa 312, however, is associated with a large increase in enzyme specific activity, thus revealing an autoinhibitory sequence between aa 313 and 392. alpha-1(1-312) still requires the phosphorylation of the activation loop Thr-172 for enzyme activity, yet is now independent of the allosteric activator, AMP. The increased levels of protein expression on transient transfection of either truncated alpha subunit cDNA are because of a decrease in enzyme turnover by pulse-chase analysis. Taken together, these data indicate that the alpha1 subunit of AMP-activated protein kinase contains several features that determine enzyme activity and stability. A constitutively active form of the kinase that does not require participation by the noncatalytic subunits provides a unique reagent for exploring the functions of AMP-activated protein kinase.  相似文献   
89.
During a 2-year period 159 malnourished children ages 3 months to 5 years with radiologic evidence of pneumonia were investigated to determine the cause of their pneumonia. In addition 119 malnourished children without pneumonia, 119 well-nourished children with pneumonia and 52 well-nourished children without pneumonia were studied as controls. Percutaneous lung aspiration was performed on 35 malnourished and 59 well-nourished children with pneumonia. Bacteria were isolated from the blood, lung or pleural fluid of 28 (18%) malnourished children with pneumonia, 42 (35%) well-nourished children with pneumonia and from the blood of 5 (4%) malnourished children without pneumonia. Streptococcus pneumoniae and Haemophilus influenzae, which were the two organisms isolated most frequently in both groups of children with pneumonia, were found in 17 (11%) malnourished and 39 (33%) well-nourished children with pneumonia. Mycobacterium tuberculosis was detected in 5 malnourished children with pneumonia. A potentially pathogenic virus was identified in 35% of malnourished children with pneumonia and 40% of well-nourished children with pneumonia, and from 25% of children without pneumonia. The viruses identified most frequently were adenovirus and respiratory syncytial virus.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
90.
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