全文获取类型
收费全文 | 434篇 |
免费 | 5篇 |
国内免费 | 7篇 |
专业分类
安全科学 | 13篇 |
废物处理 | 19篇 |
环保管理 | 118篇 |
综合类 | 56篇 |
基础理论 | 92篇 |
污染及防治 | 91篇 |
评价与监测 | 28篇 |
社会与环境 | 22篇 |
灾害及防治 | 7篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 10篇 |
2014年 | 11篇 |
2013年 | 43篇 |
2012年 | 12篇 |
2011年 | 24篇 |
2010年 | 13篇 |
2009年 | 19篇 |
2008年 | 17篇 |
2007年 | 17篇 |
2006年 | 20篇 |
2005年 | 18篇 |
2004年 | 16篇 |
2003年 | 11篇 |
2002年 | 25篇 |
2001年 | 13篇 |
2000年 | 15篇 |
1999年 | 4篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1988年 | 5篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有446条查询结果,搜索用时 15 毫秒
1.
2.
Five cases of mosaicism for an isochromosome of 20q have been detected from a total of 50 000 cases analysed for prenatal diagnosis by amniocentesis. Karyotypes were designated mos 46,X_/46,X_,i(20q). In all cases, the abnormal cell line was detected in more than one primary culture, thus fulfilling the criterion for true (level III) mosaicism. Indications for prenatal diagnosis were parental anxiety (two cases), low maternal serum alpha-fetoprotein (AFP) (two cases), and high maternal serum AFP (one case). Level II ultrasounds on all five fetuses were normal, and the abnormal cell line was never detected in fetal blood and/or cord blood. All five pregnancies were continued and had normal outcomes, with birth weights ranging from 2.4 to 3.8 kg. The development of all five children has been normal, with the oldest child in the study now 4 years of age. We suggest that the abnormal cell line in each case was of extrafetal origin, and that this may be one of the more common examples of this phenomenon, occurring in approximately 1/10000 prenatal diagnoses. Mosaicism i(20q) may have been missed in the past because of the higher resolution necessary to detect this subtle change. 相似文献
3.
4.
B. N. Chodirker M.D. A. E. Chudley K. M. Macdonald C. R. Harman J. A. Evans 《黑龙江环境通报》1994,14(11):1086-1089
This study was undertaken to evaluate the relationship between maternal serum alpha-fetoprotein (MSAFP) levels and oesophageal atresia (OA). OA occurred in 16 fetuses of mothers who had an MSAFP test in the study interval. The multiple of the median (MOM) value for MSAFP averaged 1·54 ± 0·65 (range 0·5–2·9 MOM), which was significantly higher than the value seen in controls. The median MOM was 1·35. Using a cut-off of 2·5 MOM, the sensitivity of MSAFP for detecting OA was 19 per cent. Although OA should be considered in the differential diagnosis of an elevated MSAFP level, MSAFP cannot be considered an appropriate screening test for OA given the low sensitivity. 相似文献
5.
Arie Drugan Anne Greb Mark Paul Johnson Eric L. Krivchenia Wendy R. Uhlmann Kamran S. Moghissi Mark I. Evans MD 《黑龙江环境通报》1990,10(8):483-490
Parental decisions concerning the continuation of pregnancy following prenatal detection of abnormal chromosomes were evaluated for 80 patients whose diagnosis and prenatal counselling were performed in our centre. Twenty-two anomalies were diagnosed by chorionic villus sampling (CVS) and 58 by amniocentesis. The severity of the chromosome anomaly and associated ultrasound findings in the first vs. second trimester were correlated with patients' decisions. No difference was found in the likelihood of parental decisions to interrupt or continue a pregnancy between CVS and amniocentesis for either the‘severe’ or the‘questionable’ group of chromosome anomalies. Ninety-three per cent of patients with severe prognosis and 27 per cent with questionable prognosis opted for pregnancy termination (p <0·0001). The association of ultrasound anomalies and termination was highly significant (p< 0·001). The severity of the chromosome anomaly, and, to a lesser extent, the visualization of anomalies on ultrasound were the major determinants of parental decisions to terminate the pregnancy. The diagnosis of an anomaly in the first trimester was no more likely ito lead to a termination of pregnancy than in the second trimester. 相似文献
6.
Bob Bermond 《Journal of Agricultural and Environmental Ethics》1997,10(3):227-247
The psychological literature about consciousness has been analyzed. It is argued that:
1) Only the higher symbolic cognitive powers like the ability to keep secrets, knowledge of self or self-consciousness, a
long-term view on the future, the ability to determine long-term goals, and to freely plan future behavior, add positive fitness-value
to consciousness. Without these higher intellectual abilities consciousness will have only negative fitness value and no positive
one. The intellectual powers mentioned may therefore be considered as prerequisites for consciousness. Consciousness may therefore
only be expected in those animal species that show these capacities in their behavior. So far these capacities have only been
described for the anthropoid apes and humans. For the time being, they are therefore the only species in which consciousness
may be expected.
2) Consciousness is not synchronous with real time. Human consciousness is, in as well in the perception of stimuli as in
the experience of free will to act, most times running after the facts.
3) Consciousness has to be viewed as an instinct that has been developed late in evolution. It is partially based upon primarily
innate neural circuits, fulfilling specialized cognitive functions by which information is interpreted and inferences are
made, in a more or less automatical way.
4) Most information processing concerning daily decisions,is done by parallel non-consciously functioning neural modules using
‘sloppy logic’, and only the end-product of these modules can be pushed forwards to consciousness. For this reason consciousness
will, most times, lack the necessary information to come to the correct inferences about the evaluations on which the decision
is based. Therefore, only rarely will people have insight into their cognitive processes or the real sources of their behavior.
When asked why they behaved as they did, they will produce confabulations. However, people's erroneous reports are not capricious,
but regular and systematic in such a way that they will fit the pre-existing ideas and beliefs. The contents of these reports
are therefore not based upon introspection, but, most times, on (sub)culturally accepted ideas.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
8.
9.
Craig A. Evans Kevin S. McLeary George P. Partridge Richard S. Huebner 《Journal of the American Water Resources Association》2004,40(2):409-417
ABSTRACT: Computer programs that model the fate and transport of organic contaminants through porous media typically use Fick's first law to calculate vapor phase diffusion. Fick's first law, however, is limited to the case of a single, dilute species diffusing into a stagnant, high concentration, bulk vapor phase. When dealing with more than one diffusing species and at higher concentrations, the multicomponent coupling effects on vapor phase diffusion and advection of the various constituents become significant. VLEACH, a one‐dimensional finite difference model developed for the U.S. Environmental Protection Agency (USEPA), is typical of the models using Fick's first law to model vapor‐phase diffusion. The VLEACH model was modified to accommodate up to 10 components and to calculate the binary diffusion coefficients for each of the components based on molecular weight, molecular volume, temperature and pressure, and to address the coupling effects on multiple component vapor phase diffusion and its impact on ground water. The resulting model was renamed MC‐CHEMSOIL. At low vapor phase concentrations, MC‐CHEMSOIL predicts identical ground water impacts (dissolved phase loading) to those from VLEACH 2.2a. At higher vapor phase concentrations, however, the relative difference between the models exceeded 20 percent. 相似文献
10.