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   746篇
  免费   0篇
化学工业   14篇
建筑科学   30篇
矿业工程   1篇
能源动力   2篇
水利工程   4篇
一般工业技术   4篇
冶金工业   678篇
原子能技术   2篇
自动化技术   11篇
  2020年   1篇
  2017年   1篇
  2013年   2篇
  2012年   3篇
  2011年   7篇
  2010年   6篇
  2009年   2篇
  2008年   8篇
  2007年   2篇
  2006年   2篇
  2005年   1篇
  2004年   5篇
  2003年   2篇
  2002年   2篇
  2001年   2篇
  2000年   3篇
  1999年   20篇
  1998年   184篇
  1997年   115篇
  1996年   57篇
  1995年   41篇
  1994年   28篇
  1993年   51篇
  1992年   8篇
  1991年   11篇
  1990年   15篇
  1989年   13篇
  1988年   11篇
  1987年   11篇
  1986年   12篇
  1985年   7篇
  1983年   4篇
  1982年   6篇
  1981年   2篇
  1980年   6篇
  1979年   1篇
  1978年   5篇
  1977年   26篇
  1976年   55篇
  1975年   3篇
  1974年   1篇
  1972年   1篇
  1955年   3篇
排序方式: 共有746条查询结果,搜索用时 12 毫秒
681.
This article reviews the current status of the classification and treatment of the juvenile idiopathic inflammatory myopathies. The intent of classification is to define homogeneous groups that share similar clinical features, disease courses, and responses to therapy. The classification scheme proposed includes clinicopathologic subsets, serologic subjects based on the presence of myositis-specific and myositis-associated autoantibodies, and environmental triggers of myositis. Juvenile dermatomyositis is the most common and widely recognized of these disorders. The second part reviews the history of treatment of juvenile dermatomyositis and discusses agents to consider for patients with refractory disease, unacceptable steroid toxicity, or poor prognostic factors.  相似文献   
682.
AIMS: To estimate the cost of population screening for haemochromatosis in Australia and to compare the cost of alternative screening strategies. METHODS: The costs of screening for haemochromatosis were analysed in a hypothetical study using transferrin saturation as the primary screening test, with confirmation of the diagnosis by either liver biopsy or DNA testing for the recently-described haemochromatosis gene. RESULTS: Screening, with confirmation of the diagnosis by liver biopsy, would cost between US$5079 and US$8813 per case detected (excluding administrative costs), depending on the screening strategy (Aust$ = US$0.80). If a DNA test were used instead of liver biopsy, the cost would be reduced to an estimated US$3954-US$4410 per case. This would be further reduced to US$2457 by detection of additional cases by screening family members. The least costly strategy utilised a transferrin saturation threshold of 55% and DNA testing for confirmation of the diagnosis; however, a transferrin saturation threshold of 45% increased the cost only marginally. The initial screening step (transferrin saturation) accounted for 74%-94% of the estimated cost of the screening programme. CONCLUSIONS: Screening for haemochromatosis using transferrin saturation involves relatively modest costs which may be recovered if complications of haemochromatosis can be prevented by early detection and treatment. The most cost-effective strategies utilised transferrin saturation for initial screening, followed by DNA testing. Reduction in the cost of transferrin saturation would lead to a significant reduction in total screening costs. Additional benefits of a screening programme include detection of other iron overload disorders and iron deficiency.  相似文献   
683.
A population of early to late third-stage larvae (L3) of Ascaris suum obtained from the lungs of swine 7 days after infection developed to the fourth stage (L4) in stationary, multi-well, culture plates in an atmosphere of 5% CO2 in air. Larval survival, growth and morphogenesis were evaluated in five culture systems consisting of Dulbecco's Modified Eagles' Medium alone (DM) or containing a serum supplement (DM-S) or a tripeptide (1-glycyl-1-histidyl-1-lysine) at final concentrations of 20, 200, and 1,000 ng/ml (respectively, DM-20, DM-200, and DM-1,000). The rate of development and morphogenesis of larvae from L3 to L4 was optimal in the DM-S culture system and similar to that observed in vivo. However, development beyond L4 was retarded in vitro; sex was not distinguished until 21 days in culture (DIC) and the largest L4 obtained after 52 DIC was 9.2 mm long. Although larval growth and development were similar in all systems tested through 14 days in culture, higher yields of advanced stages of L4 were obtained in systems DM-200 and DM-S. Developing larvae released metabolic products into the culture media that stimulated a specific blastogenic response in lymphocytes obtained from A. suum-infected swine.  相似文献   
684.
Orthostatic tremor, sometimes known as "shaky legs syndrome," is a disorder of middle-aged or elderly people characterized by feelings of unsteadiness in the legs and a fear of falling when standing. Patients stand on a wide base but walk normally. These symptoms are due to high-frequency (13-18 Hz) burst firing in weight-bearing muscles. They are attenuated by walking and are abolished immediately by sitting. Some authors believe that the disorder is a variant of essential tremor. This study reports the clinical and electrophysiologic features of orthostatic tremor in 30 patients. The findings indicate that orthostatic tremor is distinct from essential tremor, both clinically and electrophysiologically. The major differences are the frequency of electromyographic burst firing, the invariable involvement of lower limb and paraspinal muscles, and the task-specific nature of the tremor in orthostatic tremor. The study shows that the diagnosis can be established rapidly with surface electromyographic recordings.  相似文献   
685.
This research is part of the Sewer Mining project aimed at developing a new technological concept by extracting water from sewage by means of forward osmosis (FO). FO, in combination with a reconcentration system, e.g. reverse osmosis (RO) is used to recover high-quality water. Furthermore, the subsequent concentrated sewage (containing an inherent energy content) can be converted into a renewable energy (RE) source (i.e. biogas). The effectiveness of FO membranes in the recovery of water from sewage has been evaluated. Stable FO water flux values (>4.3 LMH) were obtained with primary effluent (screened, not treated) used as the feed solution. Fouling of the membrane was also induced and further investigated. Accumulated fouling was found to be apparent, but not irreversible. Sewer Mining could lead to a more economical and sustainable treatment of wastewater, facilitating the extraction of water and energy from sewage and changing the way it is perceived: not as waste, but as a resource.  相似文献   
686.
The implementation of wastewater reuse is becoming an increasingly important means of supplementing water supply needs and/or reducing costs. The present paper provides examples of possible uses of treated domestic effluent for the three sectors, i.e. public water supply, industrial and agricultural uses with the aim to address the feasibility of these applications. It is concluded that, although The Netherlands as a whole is considered to be a low water stressed country, regional fresh water scarcity and costs can result in the need for applications of domestic wastewater reuse.  相似文献   
687.
688.
The movement of 75 two-component hemi-arthroplasties, implanted following displaced subcapital fracture of the femoral neck, were examined radiologically in equal numbers of Hastings hips (22 mm), 22-mm Bi-articular hips and 32-mm Bi-articular hips. A classification of the movement of the two-component hemi-arthroplasty was devised. The 22-mm Bi-articular hips showed predominantly intraprosthetic movement compared with the 32-mm Bi-articular hips, where movement was mainly extraprosthetic, thus confirming in vivo the Charnley low friction principle. True bipolar movement was found predominantly in the Hastings hips. In selecting a two-component hemi-arthroplasty, the prosthesis of choice is therefore one with a 22-mm rather than a 32-mm femoral head.  相似文献   
689.
Surfactant bolus instillation has been reported to cause changes in arterial blood pressure (BP) and cerebral blood flow velocities which may increase the risk of intraventricular haemorrhage. To avoid these effects, slow tracheal infusion was evaluated as a possible alternative method of surfactant administration. Saline lung lavages were performed in 13 anesthetized and artificially ventilated adult rabbits to produce respiratory distress syndrome. Curosurf (CS, 200 mg/kg) labeled with 14C-dipalmitoyl-phosphatidylcholine (-DPPC) and/or red microspheres (RMS) was instilled into the trachea either as a single bolus (n = 8) or by infusion during 45 min via a side-channel within the wall of the tracheal tube (n = 5). An arterial cannula was placed for monitoring of blood gases and BP. To determine surfactant distribution, the lungs were cut into 60-70 pieces and radioactivity and/or the number of RMS were measured in each piece. The distribution of RMS was closely related to the distribution of 14C-DPPC (r = 0.96). Bolus instillation of CS led to a prompt and sustained increase in PaO2 (from < 10.5 to > 40 kPa within 2 min), a transient decrease in BP, and a reasonably homogeneous pulmonary surfactant distribution. Tracheal infusion of CS changed neither BP nor PaO2 during the observation period of 60 min. The pulmonary distribution of CS was extremely uneven after infusion. The distribution of exogenous surfactant and its effects on gas exchange are influenced by the instillation method. An inadequate instillation technique may add to the causes of "poor response" after surfactant replacement.  相似文献   
690.
OBJECTIVE: Reported cases of multiple personality disorder have increased dramatically in the last decade. Few data are available on the treatment of multiple personality disorder. Current recommendations are based on the experience of individual clinicians rather than on systematic research. METHOD: A questionnaire study of 305 clinicians representing a spectrum of mental health professionals was conducted to survey the types and relative efficacy of treatment modalities currently used with cases of multiple personality disorder. RESULTS: Individual psychotherapy facilitated by hypnosis was uniformly endorsed as the primary treatment by all practitioner groups. The average patient was in twice-weekly psychotherapy facilitated by hypnosis for 3.8 years. Antidepressant and anxiolytic medications were reported to be moderately useful adjunctive treatments. CONCLUSIONS: These findings support current impressionistic treatment recommendations for multiple personality disorder regarding the primacy of psychotherapy and the moderate benefits of psychopharmacology with antidepressant and antianxiety agents.  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