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   2010篇
  免费   1篇
化学工业   18篇
金属工艺   2篇
建筑科学   1篇
轻工业   2篇
无线电   1篇
一般工业技术   7篇
冶金工业   1966篇
原子能技术   1篇
自动化技术   13篇
  2022年   1篇
  2021年   3篇
  2020年   1篇
  2018年   2篇
  2016年   1篇
  2013年   5篇
  2012年   2篇
  2011年   2篇
  2010年   2篇
  2008年   4篇
  2007年   2篇
  2006年   2篇
  2004年   1篇
  2003年   6篇
  1999年   71篇
  1998年   705篇
  1997年   385篇
  1996年   229篇
  1995年   117篇
  1994年   111篇
  1993年   114篇
  1992年   16篇
  1991年   21篇
  1990年   10篇
  1989年   18篇
  1988年   9篇
  1987年   14篇
  1986年   9篇
  1985年   15篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1981年   7篇
  1980年   12篇
  1978年   2篇
  1977年   32篇
  1976年   67篇
  1975年   4篇
  1974年   1篇
  1966年   1篇
  1955年   1篇
  1954年   1篇
排序方式: 共有2011条查询结果,搜索用时 0 毫秒
121.
In this study, we investigated the induction of cellular gene expression by the Epstein-Barr Virus (EBV) latent membrane protein 1 (LMP1). Previously, LMP1 was shown to induce the expression of ICAM-1, LFA-3, CD40, and EBI3 in EBV-negative Burkitt lymphoma (BL) cells and of the epidermal growth factor receptor (EGF-R) in epithelial cells. We now show that LMP1 expression also increased Fas and tumor necrosis factor receptor-associated factor 1 (TRAF1) in BL cells. LMP1 mediates NF-kappaB activation via two independent domains located in its C-terminal cytoplasmic tail, a TRAF-interacting site that associates with TRAF1, -2, -3, and -5 through a PXQXT/S core motif and a TRADD-interacting site. In EBV-transformed B cells or transiently transfected BL cells, significant amounts of TRAF1, -2, -3, and -5 are associated with LMP1. In epithelial cells, very little TRAF1 is expressed, and only TRAF2, -3, and -5, are significantly complexed with LMP1. The importance of TRAF binding to the PXQXT/S motif in LMP1-mediated gene induction was studied by using an LMP1 mutant that contains alanine point mutations in this motif and fails to associate with TRAFs. This mutant, LMP1(P204A/Q206A), induced 60% of wild-type LMP1 NF-kappaB activation and had approximately 60% of wild-type LMP1 effect on Fas, ICAM-1, CD40, and LFA-3 induction. In contrast, LMP1(P204A/Q206A) was substantially more impaired in TRAF1, EBI3, and EGF-R induction. Thus, TRAF binding to the PXQXT/S motif has a nonessential role in up-regulating Fas, ICAM-1, CD40, and LFA-3 expression and a critical role in up-regulating TRAF1, EBI3, and EGF-R expression. Further, D1 LMP1, an LMP1 mutant that does not aggregate failed to induce TRAF1, EBI3, Fas, ICAM-1, CD40, and LFA-3 expression confirming the essential role for aggregation in LMP1 signaling. Overexpression of a dominant form of IkappaBalpha blocked LMP1-mediated TRAF1, EBI3, Fas, ICAM-1, CD40, and LFA-3 up-regulation, indicating that NF-kappaB is an important component of LMP1-mediated gene induction from both the TRAF- and TRADD-interacting sites.  相似文献   
122.
Few guidelines are available with which to facilitate treatment in patients with noniatrogenic injuries of the esophagus. Early diagnosis and proper management are essential if a good outcome is to be expected. In an effort to define better the treatment of patients with penetrating and blunt injuries of the esophagus, we report our recent 5-year experience at an urban trauma center. From July 1988 to June 1993, nineteen patients with esophageal perforations from penetrating (18) and blunt (1) trauma were identified by our trauma registry. There was no mortality in this group of patients and morbidity was mostly due to associated injuries. Eleven cervical esophageal injuries were repaired. One cervical injury was treated by stopping oral intake and giving intravenous antibiotics. The neck was not drained in 10 of the surgical cases. In 1 patient a tracheoesophageal fistula developed, which later was repaired with a pectoralis muscle flap. Seven perforations were identified in the thoracic (2) and abdominal (5) portions of the esophagus. All were due to gunshot wounds. In 4 cases, a fundal wrap was used to reinforce the repairs. Postoperative contrast studies confirmed that all repairs were intact. We conclude that penetrating and blunt tears of the esophagus can be repaired safely with minimal mortality. Morbidity is usually from associated injuries such as to the spinal cord and trachea. When identified early, cervical esophageal injuries do not need to be drained routinely.  相似文献   
123.
This clinical research plan was designed to evaluate the predictable and current developments, growth, and stability of the economic status of part-time or full-time African-American practicing surgeons. In many communities throughout the United States, the economic successes of certified or experienced black surgical specialists are inhibited or modified by mistrust, jealousy, professional disengagements, prejudices, and self-hatred by black and white physicians and lay African Americans. Nevertheless, there are subtle and overt evidences of increasing satisfactory and above average associative interprofessional relationships between African-American physicians and surgical specialists. One hundred African-American surgical specialists from thirty-four communities in the United States were interviewed at periodic intervals over a period of three decades. Recommendations for improvements and changes are presented.  相似文献   
124.
HISTORY AND CLINICAL FINDINGS: A 47-year-old man in a reduced general condition, presumed to be a chronic alcoholic, was hospitalised in a sleepy state and impaired level of consciousness (Glasgow Coma Scale 8). There were no focal neurological deficits, but all proprioceptor reflexes were weak. Body temperature was 36.8 degrees C, blood pressure 90/60 mm Hg, and heart rate 80/min. INVESTIGATIONS: Biochemical tests showed sodium concentration reduced to 121 mmol/l, potassium to 1.83 mmol/l, chloride to 55 mmol/l and, on the next day, phosphate to 0.11 mmol/l. Blood gas analysis demonstrated a noncompensated respiratory alkalosis (pH 7.69, bicarbonate 39.5 mmol/l and a base excess of 20 mmol/l. TREATMENT AND COURSE: The impaired consciousness was thought to be due to the marked alkalosis in combination with hypophosphataemia. The alkalosis was completely removed within 48 hours by administration of Ringer's solution and potassium chloride concentrate, without sodium chloride Phosphate deficit was neutralised with KH2PO4 infusion. Normal consciousness was restored. CONCLUSIONS: Even severe hypochloraemic alkalosis can be quickly reversed with infusion of chloride without sodium Successful treatment with chloride alone excludes alkalosis induced by mineralocorticoids.  相似文献   
125.
OBJECTIVES: This study sought to define specialty-related differences in the care and outcome of patients admitted to the hospital with congestive heart failure (CHF). BACKGROUND: Congestive heart failure is the leading diagnosis-related group (DRG) discharge diagnosis in the United States and accounts for an estimated annual hospital cost in excess of $7 billion. The clinical impact of aggressive CHF management and the importance of the subspecialist in guiding this care have not been evaluated. METHODS: To define differences in physician practice patterns, we performed a chart review of consecutive patients admitted to a university teaching hospital with a primary DRG discharge diagnosis of CHF. We compared treatment and outcome of patients cared for by a generalist (n = 160) and those whose care was guided by a cardiologist (n = 138) during their index hospital period with CHF and over the next 6 months. RESULTS: At our institution, > 50% of patients admitted to the hospital with CHF cared for by generalists alone had minimal (New York Heart Association functional class I or II) symptoms, compared with < 15% of those cared for by a cardiologist (p < 0.01). Although generalists' patients underwent significantly fewer in-hospital diagnostic tests and had shorter lengths of stay, they had a 1.7-fold increased risk of readmission for CHF within 6 months (p < 0.05). Six-month cardiac and all-cause mortality were not significantly different between the groups. The type of physician caring for the patient and a history of diabetes, previous CHF or myocardial infarction were independent predictors of readmission for CHF. CONCLUSIONS: Involvement of a cardiologist in the care of patients admitted to the hospital with CHF is associated with increased use of diagnostic testing, longer hospital stays and improved clinical outcome. These results substantiate practice guidelines that suggest a role for cardiologists in the care of symptomatic patients with CHF.  相似文献   
126.
The sugar residues in glycoconjugates present in the parotid and mandibular glands of the adult fallow-deer were detected and characterized by using a battery of eight different lectin-horseradish peroxidase conjugates. In some cases a treatment with sialidase preceded the lectin staining. Parotid secretory cells produced glycoconjugates with N-acetylgalactosamine, N-acetylglucosamine and mannose residues. Mucous acinar cells were the most reactive sites of the mandibular gland and contained conspicuous quantities of oligosaccharides with terminal sialic acid radicals. Galactosil-(beta 1-->3)N-acetylgalactosamine was the most abundant penultimate sugar linked to N-acetylneuraminic acid. Mandibular mucous cells also presented N-acetylglucosamine and sialylated components with the terminal dimer sialic acid-N-acetylgalactosamine. Demilunar cells contained glycoconjugates with fucose and mannose residues. The apical surface of duct cells was stained by all the lectins.  相似文献   
127.
Both fast neutron radiotherapy and boron neutron capture therapy have been investigated as new radiation treatment techniques for patients with malignant gliomas. While each of these techniques individually has shown the potential for pathological eradication of malignant glioma, to date neither has evolved into an accepted, improved method of treatment. We have recently begun a research program investigating the feasibility of combining the benefits of both types of therapy. As a fast neutron beam penetrates tissue some of the particles are degraded to thermal energies. These can be captured by 10B or other suitable isotopes resulting in a highly-localized release of additional energy during a course of fast neutron radiotherapy. In this article we will review the rationale for such an approach, and review the underlying physics as well as in vitro, in vivo, and early human studies testing its feasibility. If appropriate carrier agents can be found that preferentially-localize in tumor cells, this approach ena be applied to many different tumor systems.  相似文献   
128.
129.
A prospective, open, multicentre study was performed to investigate the efficacy and safety of long-term treatment with cyclosporin in adults with severe atopic dermatitis. Subjects were treated for a maximum of 48 weeks. For the first 8 weeks, cyclosporin was administered at 2.5 mg/kg per day. The dose was then adjusted according to response. Disease activity was monitored using the six-area, six-sign score and the proportion of skin involved. Pruritus and sleep disturbance were assessed using four-point scales. Response was further evaluated on a five-point scale. Adverse events, blood pressure and serum biochemistry were monitored. Tolerability was assessed on a five-point scale. One hundred subjects were enrolled and 65 completed 48 weeks of treatment. Withdrawals occurred due to remission (three), inadequate response (seven), protocol violations (11) and adverse events (14, of which seven were probably treatment related). Cyclosporin produced rapid and highly significant improvements in all indices of disease activity. Sixty-five subjects considered that they had shown a considerable improvement or complete clearance of disease. Most patients relapsed after cessation of treatment, but neither signs nor symptoms had returned to baseline severity 8 weeks later. Blood pressure and serum creatinine levels increased slightly, and in one subject renal impairment was a major factor contributing to withdrawal of the drug. Overall, 85 subjects rated the tolerability of cyclosporin as good or very good. The results indicate that cyclosporin has a place in the long-term treatment of severe atopic dermatitis provided that appropriate patients are selected and careful monitoring is performed.  相似文献   
130.
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