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   649篇
  免费   8篇
  国内免费   10篇
安全科学   63篇
废物处理   17篇
环保管理   158篇
综合类   134篇
基础理论   151篇
污染及防治   90篇
评价与监测   31篇
社会与环境   18篇
灾害及防治   5篇
  2024年   4篇
  2023年   7篇
  2022年   4篇
  2021年   14篇
  2020年   16篇
  2019年   7篇
  2018年   18篇
  2017年   15篇
  2016年   26篇
  2015年   17篇
  2014年   22篇
  2013年   45篇
  2012年   19篇
  2011年   41篇
  2010年   20篇
  2009年   28篇
  2008年   30篇
  2007年   31篇
  2006年   33篇
  2005年   32篇
  2004年   20篇
  2003年   22篇
  2002年   25篇
  2001年   14篇
  2000年   20篇
  1999年   6篇
  1998年   8篇
  1997年   5篇
  1996年   9篇
  1995年   11篇
  1994年   10篇
  1993年   6篇
  1992年   9篇
  1991年   8篇
  1990年   5篇
  1988年   8篇
  1987年   5篇
  1986年   3篇
  1985年   4篇
  1984年   2篇
  1983年   5篇
  1982年   6篇
  1981年   10篇
  1980年   6篇
  1979年   2篇
  1977年   2篇
  1974年   1篇
  1973年   1篇
  1962年   1篇
  1956年   1篇
排序方式: 共有667条查询结果,搜索用时 0 毫秒
51.
    
  相似文献   
52.
In utero sonographic diagnoses from forty-five malformed infants were correlated with their autopsy findings. Fifty-two malformations were diagnosed prenatally in 42 of the patients but 90 additional malformations were not. Nine sonographically diagnosed abnormalities were not confirmed at autopsy. Factors compromising sonographic diagnosis included: limited examinations, small fetal size, timing of examination, oligohydramnios, fetal position, nature of the malformation and unfamiliarity of the ultrasonographer with specific malformation syndromes. In vitro ultrasonography is an invaluable tool of diagnosing congenital malformations but has limitations.  相似文献   
53.
54.
    
A requirement for geostatistical prediction is estimation of the variogram from the data. Often low sample size is a major impediment to elucidating a variogram even for a highly autocorrelated spatial process. This paper presents a methodology for improving variogram estimation when samples exist from multiple years or regions sharing a similar process for generating spatial autocorrelation. Such samples may come from annual monitoring programs for natural resources or from multiple geologic regions. As each set of samples contains some information on the spatial autocorrelation, combining information through the construction of a combined variogram cloud and binning to obtain a common variogram improves the estimation of the variogram. In both simulations and in real datasets of oyster abundance the method proposed here reduces the likelihood of failing to obtain a variogram from a set of samples and improves the efficiency of variogram estimation. In practice, the benefits obtained by estimating an otherwise elusive variogram generally outweigh the costs of using a slightly incorrect variogram model if different sampling stanzas are combined when they do not share the same spatial autocorrelation. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
55.
Several compositions of Fenton's Reagent and hydrogen peroxide alone were used to disinfect combined sewage samples from a wastewater treatment facility. The presettled samples contained suspended solids (SS) and dissolved organic carbon (DOC) at concentrations of 28 and 290 mg/L, respectively. Disinfection with Fenton's Reagent was carried out at a pH between 5.90 and 6.0 and at a temperature of 25°C. All disinfected samples contained residual oxidants. Under all reaction conditions studied, complete inactivation of E. coli was achieved within one minute of the addition of Fenton's Reagent. Disinfection with hydrogen peroxide alone under similar conditions is incomplete even under much longer contact times. © 2009 Wiley Periodicals, Inc.  相似文献   
56.
57.
58.
    
A wide spectrum of genetic causes may lead to nonimmune hydrops fetalis (NIHF), and a thorough phenotypic and genetic evaluation are essential to determine the underlying etiology, optimally manage these pregnancies, and inform discussions about anticipated prognosis. In this review, we outline the known genetic etiologies of NIHF by fetal organ system affected, and provide a systematic approach to the evaluation of NIHF. Some of the underlying genetic disorders are associated with characteristic phenotypic features that may be seen on prenatal ultrasound, such as hepatomegaly with lysosomal storage disorders, hyperechoic kidneys with congenital nephrosis, or pulmonary valve stenosis with RASopathies. However, this is not always the case, and the approach to evaluation must include prenatal ultrasound findings as well as genetic testing and many other factors. Genetic testing that has been utilized for NIHF ranges from standard chromosomal microarray or karyotype to gene panels and broad approaches such as whole exome sequencing. Family and obstetric history, as well as pathology examination, can yield additional clues that are helpful in establishing a diagnosis. A systematic approach to evaluation can guide a more targeted approach to genetic evaluation, diagnosis, and management of NIHF.  相似文献   
59.
60.
    
With improvements in early diagnosis and management of genetic diseases, more women with genetic disorders are reaching reproductive age and becoming pregnant. While pregnancy can have a significant impact on a woman's health when there is an underlying genetic disorder, there can also be fetal effects, including embryopathy, fetal growth restriction, and brain injury. Some maternal genetic disorders are associated with adverse perinatal outcomes, including a high risk of perinatal loss and preterm birth. In this article, we review several maternal genetic disorders associated with fetal risk that are important for clinicians and patients to understand and manage appropriately. These include phenylalanine hydroxylase (PAH) deficiency and other inborn errors of metabolism, tuberous sclerosis complex, myotonic dystrophy, cystic fibrosis, Turner syndrome, sickle cell disease, and connective tissue disorders.  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