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   89篇
  免费   4篇
  国内免费   1篇
管理学   29篇
人口学   3篇
理论方法论   3篇
综合类   9篇
社会学   7篇
统计学   43篇
  2022年   1篇
  2021年   2篇
  2020年   4篇
  2019年   6篇
  2018年   5篇
  2017年   5篇
  2016年   1篇
  2015年   5篇
  2014年   3篇
  2013年   13篇
  2012年   8篇
  2011年   1篇
  2009年   2篇
  2008年   2篇
  2007年   2篇
  2006年   4篇
  2005年   1篇
  2004年   3篇
  2003年   2篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   3篇
  1993年   4篇
  1992年   2篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1982年   1篇
排序方式: 共有94条查询结果,搜索用时 15 毫秒
11.
微生物的群体组成是决定生物处理系统降解污染物能力的重要因素之一,在利用软体动物门腹足纲微型动物——卷贝进行活性污泥减量的应用研究基础上,本文利用醌指纹法分析了活性污泥被卷贝摄食前后的微生物的群体组成.结果表明,在500 ind/m3~5000 ind/m3密度范围内活性污泥中卷贝的存在对微生物的多样性及种的均匀性没有明显影响,从而为生物法减量活性污泥的污水处理系统的进一步研究奠定基础.  相似文献   
12.
Staudte  R.G.  Zhang  J. 《Lifetime data analysis》1997,3(4):383-398
The p-value evidence for an alternative to a null hypothesis regarding the mean lifetime can be unreliable if based on asymptotic approximations when there is only a small sample of right-censored exponential data. However, a guarded weight of evidence for the alternative can always be obtained without approximation, no matter how small the sample, and has some other advantages over p-values. Weights of evidence are defined as estimators of 0 when the null hypothesis is true and 1 when the alternative is true, and they are judged on the basis of the ensuing risks, where risk is mean squared error of estimation. The evidence is guarded in that a preassigned bound is placed on the risk under the hypothesis. Practical suggestions are given for choosing the bound and for interpreting the magnitude of the weight of evidence. Acceptability profiles are obtained by inversion of a family of guarded weights of evidence for two-sided alternatives to point hypotheses, just as confidence intervals are obtained from tests; these profiles are arguably more informative than confidence intervals, and are easily determined for any level and any sample size, however small. They can help understand the effects of different amounts of censoring. They are found for several small size data sets, including a sample of size 12 for post-operative cancer patients. Both singly Type I and Type II censored examples are included. An examination of the risk functions of these guarded weights of evidence suggests that if the censoring time is of the same magnitude as the mean lifetime, or larger, then the risks in using a guarded weight of evidence based on a likelihood ratio are not much larger than they would be if the parameter were known.  相似文献   
13.
ABSTRACT

The article examines job satisfaction in 21 Italian call centres. The results of research carried out on 1715 handlers indicate how dissatisfaction prevails among call centre representatives (CCRs) and how it is influenced by aspects related to some organisational characteristics (service delivered, size and organisational typology), on one side, and to different aspects of working conditions (contract, wage and tenure) and participants’ biographical and working profiles of CCRs (gender, age, educational attainment), on the others. However, the most interesting finding emerges by distinguishing different dimensions of job satisfaction (extrinsic and intrinsic-relational). In particular, the relationship between type of contract and job satisfaction is rather interesting. For non-permanent workers, in fact, the probability of being dissatisfied is decidedly greater if we consider the extrinsic dimension of job satisfaction. Instead, when the intrinsic-relational dimension is taking into account, atypical workers are no more dissatisfied than the permanent ones. Job insecurity and limited perspectives in terms of work alternatives, safeguards and rewards, seem to be the source of greatest dissatisfaction for Italian CCRs. This certainly does not surprise considering the Italian development model and its dualistic labour market, highly segmented between insiders and outsiders.  相似文献   
14.
借助Antconc语料库检索软件及人工统计的方法,通过自建两个小型专用语料库,选取世界500强中10家中外企业的简介文本进行对比分析。研究发现,外国企业简介和中国企业简介呈现明显不同的词汇特征、句子特征和语篇特征。针对此,文章提出了英译中国企业简介的若干实用策略,即增加第一人称;删减冗余信息;改变语态和主语,突出重点内容。研究结果对中国企业在走向全球化过程中如何更好地解读自己、诠释自己、宣传自己具有重要的借鉴价值。  相似文献   
15.
Abstract

“Herpes Simplex Virus Proctitis in Homosexual Men: Clinical, Sigmoidoscopic, and Histopathological Features,” Steven E. Goodell, Thomas C. Quinn, Emmanuel Mkrtichian, Michael D. Schuffler, King K. Holmes, and Lawrence Corey. Acute herpes simplex virus (HSV) infection was detected in 23 of 102 consecutively examined, sexually active male homosexuals who presented with anorectal pain, discharge, tenesmus, or hematochezia, as compared with 3 of 75 homosexual men without gastrointestinal symptoms (P < 0.01). Findings that were significantly more frequent in men with HSV proctitis than in men with proctitis due to other infectious causes included fever (48 per cent), difficulty urinating (48 per cent), sacral paresthesias (26 per cent), inguinal lymphadenopathy (57 per cent), severe anorectal pain (100 per cent), tenesmus (100 per cent), constipation (78 per cent), perianal ulcerations (70 per cent), and the presence of diffuse ulcerative or discrete vesicular or pustular lesions in the distal 5 cm of the rectum (50 per cent). Serologic evidence indicated that 85 per cent of the men with symptomatic HSV proctitis were having their first episode of HSV-2 infection. The diagnosis of HSV proctitis is suggested by the presence of severe anorectal pain, and diffuse ulceration of the distal rectal mucosa. (New England Journal of Medicine 1983;308:868–71.)  相似文献   
16.
Methods are needed to improve the ability of biomonitoring and epidemiological studies to identify potential carcinogenic hazards and to quantify human risk. The limitations of pharmacokinetic models can be mitigated by the direct measurement of molecular markers of biologically effective dose of carcinogen. Parallel animal and human studies are recommended as a means of validating these markers.  相似文献   
17.
Environmental tobacco smoke (ETS)has recently been determined by U.S. environmental and occupational health authorities to be a human carcinogen. We develop a model which permits using atmospheric nicotine measurements to estimate nonsmokers’ETS lung cancer risks in individual workplaces for the first time. We estimate that during the 1980s, the U.S. nonsmoking adult population's median nicotine lung exposure (homes and workplaces combined)was 143 micrograms (μg)of nicotine daily, and that most-exposed adult nonsmokers inhaled 1430 μg/day. These exposure estimates are validated by pharmacokinetic modeling which yields the corresponding steady-state dose of the nicotine metabolite, cotinine. For U.S. adult nonsmokers of working age, we estimate median cotinine values of about 1.0 nanogram per milliliter (ng/ml)in plasma, and 6.2 ng/ml in urine; for most-exposed nonsmokers, we estimate cotinine concentrations of about 10 ng/ml in plasma and 62 ng/ml in urine. These values are consistent to within 15% of the cotinine values observed in contemporaneous clinical epidemiological studies. Corresponding median risk from ETS exposure in U.S. nonsmokers during the 1980s is estimated at about two lung cancer deaths (LCDs)per 1000 at risk, and for most-exposed nonsmokers, about two LCDs per 100. Risks abroad appear similar. Modeling of the lung cancer mortality risk from passive smoking suggests that de minimis [i.e., “acceptable” (10-6)], risk occurs at an 8-hr time-weighted-average exposure concentration of 7.5 nanograms of ETS nicotine per cubic meter of workplace air for a working lifetime of 40 years. This model is based upon a linear exposure-response relationship validated by physical, clinical, and epidemiological data. From available data, it appears that workplaces without effective smoking policies considerably exceed this de minimis risk standard. For a substantial fraction of the 59 million nonsmoking workers in the U.S., current workplace exposure to ETS also appears to pose risks exceeding the de manifestos risk level above which carcinogens are strictly regulated by the federal government.  相似文献   
18.
Dose proportionality/linearity is a desirable property in pharmacokinetic studies. Various methods have been proposed for its assessment. When dose proportionality is not established, it is of interest to evaluate the degree of departure from dose linearity. In this paper, we propose a measure of departure from dose linearity and derive an asymptotic test under a repeated measures incomplete block design using a slope approach. Simulation studies show that the proposed method has a satisfactory small sample performance in terms of size and power.  相似文献   
19.
《Journal of women & aging》2013,25(1-2):27-46
SUMMARY

This study focuses on gender differences in health profiles, and examines which health profiles drive gender differences in remaining life expectancy in women and men aged 65 and over in The Netherlands. Data from the first two cycles of the Longitudinal Aging Study Amsterdam (n = 2,141 and 1,659, respectively) were used to calculate health profiles for individuals of 65–85 years. For both women and men, six profiles were found: I. cancer; II. “other” chronic diseases; III. cognitive impairment; IV. frailty or multimorbidity; V. cardiovascular diseases; and VI. good health. The further characterization of these types showed some gender differences. Remaining life expectancy for women was greater than for men in each health profile. A decomposition into health expectancies showed that both women and men could expect to live about 5 years in good health from age 66. The greatest gender differences in years spent with health problems were found for profile IV and for profile III. Their greater number of years spent in these health states have direct consequences for the type and cost of care women need.  相似文献   
20.
Geometric profiles can be modeled effectively by large and small scale components. In several articles, a regression model with spatial autoregressive error term is combined with control charts to monitor geometric profiles. However, once a signal occurs, control charts would not be able to determine whether the shift is due to the large or small scale component. In this article, a combination of a multivariate and an omnibus control charts is used to monitor the large scale and small scale components to determine whether the shift is due to the large scale or small scale components.  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