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   350篇
  免费   1篇
电工技术   3篇
化学工业   14篇
金属工艺   3篇
机械仪表   2篇
建筑科学   11篇
能源动力   1篇
轻工业   16篇
无线电   46篇
一般工业技术   40篇
冶金工业   206篇
原子能技术   2篇
自动化技术   7篇
  2011年   4篇
  2010年   9篇
  2009年   6篇
  2008年   7篇
  2007年   8篇
  2006年   4篇
  2005年   9篇
  2004年   8篇
  2003年   5篇
  2002年   5篇
  2001年   7篇
  2000年   3篇
  1999年   5篇
  1998年   31篇
  1997年   31篇
  1996年   17篇
  1995年   13篇
  1994年   8篇
  1993年   11篇
  1992年   4篇
  1991年   7篇
  1990年   5篇
  1989年   11篇
  1988年   8篇
  1987年   4篇
  1986年   10篇
  1985年   4篇
  1984年   3篇
  1983年   3篇
  1982年   3篇
  1981年   5篇
  1980年   3篇
  1979年   6篇
  1978年   5篇
  1977年   6篇
  1976年   6篇
  1974年   8篇
  1973年   4篇
  1969年   6篇
  1968年   2篇
  1966年   4篇
  1965年   3篇
  1963年   2篇
  1962年   3篇
  1960年   2篇
  1957年   2篇
  1956年   2篇
  1936年   2篇
  1935年   3篇
  1931年   2篇
排序方式: 共有351条查询结果,搜索用时 8 毫秒
11.
Age-density fractionation, in-vitro erythrophagocytosis, and enumeration of membrane-bound antibodies were monitored for circulating red blood cells (RBC) from five anemic patients with myelodysplastic syndromes (MDS), in relation to administration of recombinant human erythropoietin (rhEPO). The density distribution patterns of erythrocytes from the patients prior to treatment were in accordance with their inability to produce compensating levels of circulating RBC. The complete response of one patient to rhEPO and partial responses of two other patients were accompanied by shifts to larger proportions of low density (young) RBC. In vitro phagocytosis of density-fractionated RBC from the complete responder was similar to those of age-matched non-anemic donors. Elevated erythrophagocytosis prior to rhEPO administration was observed for the partial responders and further increased during treatment in one, suggesting the stimulation of abnormal progenitors producing highly defective erythrocytes. There was no correlation between levels of erythrophagocytosis and RBC membrane-bound immunoglobulins in this group of patients. Our findings suggest that density distribution analysis of circulating RBC coupled with in vitro erythrophagocytosis may provide useful predictive tools for selecting potential responders to rhEPO administration among anemic MDS patients.  相似文献   
12.
13.
The osmotic pressure of very dilute liquid mixtures of3He in4He has been measured for the concentration range 0.08–0.6 mole%3He, and the temperature range 20–400 mK. The results are used to check the validity of different proposals for the3He–3He effective interaction.Work supported in part by the Gerald I. Swope Fund and the Batsheva de Rothschild Foundation.  相似文献   
14.
An analytical stochastic model to predict relevant statistical scattering features of electromagnetic waves propagating within vegetated environments is presented. The propagation phenomena are described by formulating the scattering associated with random permittivity fluctuations superimposed on a lossy deterministic background slab. The distorted wave Born approximation is employed to determine the backscattered power, and its temporal spectrum.  相似文献   
15.
Current theory suggests that temporal–limbic dysfunction is responsible for schizophrenic symtomatology. Such theory dovetails with many reports of a higher frequency of schizophreniform psychoses in temporal lobe epilepsy (TLE) than is found with other forms of seizure activity. To explore the possibility of a common neurological substrate for the 2 disorders, a variable foreperiod reaction-time task, on which early crossover has been found to be characteristic of many schizophrenics, was administered to 11 schizophrenics, 12 TLE patients, 9 generalized seizure patients, and 10 normal controls. Results show that only TLE and schizophrenic Ss showed an early crossover of regular and irregular preparatory interval gradients. Discussion focuses on the status of crossover as a marker variable, and relevant animal and human lesion literature is reviewed. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
16.
Neonatal emergencies have become more common as increasingly sophisticated Neonatal Intensive Care Units graduate lower birth-weight babies born at younger gestational ages. These patients present a number of challenges to emergency physicians. They are often discharged with apnea monitors, which generate a high number of false alarms. Neonatal Intensive Care Unit graduates, however, are predisposed to a number of conditions that can result in true episodes of apnea. We present such a case and will discuss the unusual underlying cause of apnea, the utility of apnea monitors, and the need for emergency physicians to be prepared to evaluate and treat these potentially complicated patients.  相似文献   
17.
Quantifying the turn-on behavior of electrostatic discharge (ESD) protection devices under subnanosecond transients is critical to achieving robust protection against the Charged Device Model stress. A wafer-level very fast transmission-line pulse system (VFTLP) has been developed and is shown to successfully measure the turn-on time of a common ESD protection device. Both formal analysis and practical details regarding VFTLP system construction and operation are documented  相似文献   
18.
19.
A central theme of research on human development and psychopathology is whether a therapeutic intervention or a turning-point event, such as a family break-up, alters the trajectory of the behavior under study. This article describes and applies a method for using observational longitudinal data to make more transparent causal inferences about the impact of such events on developmental trajectories. The method combines 2 distinct lines of research: work on the use of finite mixture modeling to analyze developmental trajectories and work on propensity score matching. The propensity scores are used to balance observed covariates and the trajectory groups are used to control pretreatment measures of response. The trajectory groups also aid in characterizing classes of subjects for which no good matches are available. The approach is demonstrated with an analysis of the impact of gang membership on violent delinquency based on data from a large longitudinal study conducted in Montréal, Canada. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
20.
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