全文获取类型
收费全文 | 1423篇 |
免费 | 6篇 |
国内免费 | 42篇 |
专业分类
安全科学 | 45篇 |
废物处理 | 86篇 |
环保管理 | 142篇 |
综合类 | 240篇 |
基础理论 | 340篇 |
环境理论 | 1篇 |
污染及防治 | 393篇 |
评价与监测 | 100篇 |
社会与环境 | 118篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 13篇 |
2022年 | 45篇 |
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 14篇 |
2018年 | 54篇 |
2017年 | 22篇 |
2016年 | 28篇 |
2015年 | 49篇 |
2014年 | 35篇 |
2013年 | 119篇 |
2012年 | 36篇 |
2011年 | 63篇 |
2010年 | 61篇 |
2009年 | 72篇 |
2008年 | 70篇 |
2007年 | 60篇 |
2006年 | 44篇 |
2005年 | 43篇 |
2004年 | 77篇 |
2003年 | 65篇 |
2002年 | 43篇 |
2001年 | 102篇 |
2000年 | 43篇 |
1999年 | 24篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 9篇 |
1995年 | 20篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1980年 | 6篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 7篇 |
1972年 | 12篇 |
1971年 | 5篇 |
1966年 | 5篇 |
1965年 | 5篇 |
1959年 | 5篇 |
1957年 | 5篇 |
排序方式: 共有1471条查询结果,搜索用时 375 毫秒
931.
R. Achiron MD Z. Gottlieb Y. Yaron M. Gabbay U. Gabbay S. Lipitz S. Mashiach 《黑龙江环境通报》1995,15(2):155-160
Our objective was to establish nomograms for fetal eye measurements from 12 weeks' gestation by using transvaginal and transabdominal high-resolution ultrasound techniques. A prospective cross-sectional study was performed on 450 normal singleton pregnancies between 12 and 37 weeks' gestation. Vitreous and lens circumferences were measured by transvaginal ultrasonography until 17 weeks, and by abdominal ultrasound between 18 and 37 weeks' gestation. Regression analyses were used to create nomograms, and several transformations were done to obtain linearity. Eye measurements of 12 fetuses at risk for ocular disturbances were plotted on the constructed nomograms. Linear relationships were fitted between vitreous (r2=0.79) and lens (r2=0.88) circumferences and gestational age. In addition, there was a significant correlation between these measurements and the biparietal diameter. Data of the fetuses at risk showed that disturbances in ocular growth were associated mainly with abnormal cerebral development. These normative data may be helpful in the prenatal diagnosis of suspected congenital syndromes that include, among their manifestations, ocular growth disturbances such as microphthalmos and anophthalmos. 相似文献
932.
933.
934.
Coal combustion power plant flyash materials have been reported as useful soil amendments with agronomic and environmental benefits. This paper reports the efficacy of fluidized bed combustion (FBC) and flue gas desulfurization (FGD) byproducts, when amended with dairy, swine, and broiler litter manures, in reducing phosphorus (P) solubility and potential impact on water quality. At a rate of 400 g/kg, FBC reduced water soluble P by 60% for dairy and swine and 50% for broiler litter, as compared to un-treated control samples. Byproduct FGD had little effect when amended into dairy manure, but reduced water soluble P by nearly 80% when amended into swine and broiler manure at a rate of 250 g/kg. The amount of Ca added in the amendments together with pH of the mixture is the major contributing factor in soluble P reduction. Sequential extraction results showed that the flyash treatments shifted water soluble P into mainly bicarbonate extractable P. The latter is still considered available for crop uptake but less vulnerable for environmental losses. Coal combustion byproducts, when amended into manure and used properly, can provide a useful and viable option for improving nutrient management on animal farms. 相似文献
935.
Intrauterine fetal brain death is a rare cause of a fixed fetal heart rate pattern. Seven cases have been previously reported in the literature, but only two of them were diagnosed prenatally and all the newborns died soon after delivery. Two additional cases of antepartum diagnosis of intrauterine fetal brain death, managed expectantly, are reported. We had the unique opportunity to document progressive sonographic cerebral changes during the follow-up period, following the neurological event, while the fetus continued life and growth in utero. The cardiographic and sonographic findings suggesting intrauterine fetal brain death were a prolonged fixed fetal heart rate, even following a vibroacoustic and contraction stress test; an atonic fetus without breathing and body movement; and the appearance of hydramnios and the development of ventriculomegaly. 相似文献
936.
937.
938.
939.
In this study the biosorption of Yellow RL, a metal-complex anionic dye, by dried Rhizopus arrhizus, a filamentous fungus, was investigated as a function of initial solution pH, initial dye concentration and initial salt (sodium chloride) concentration. The fungus exhibited the maximal dye uptake at pH 2 in the absence and in the presence of salt. Dye uptake increased with the dye concentration up to 1000 mg l?1 and diminished considerably in the presence of increasing concentrations of salt up to 50 g l?1. The fungus biosorbed 85.4 mg dye g?1of dried biomass at 100 mg l?1 initial dye concentration in the absence of salt. When 50 g l?1 salt was added to the biosorption medium, this value dropped to 60.8 mg g?1 resulting in 28.8% reduction in biosorption capacity. The Redlich–Peterson and Langmuir–Freundlich were the most suitable adsorption models for describing the biosorption equilibrium data of the dye both individually and in salt containing medium. The pseudo-second-order and saturation type kinetic models depicted the biosorption kinetics accurately for all cases studied. Equilibrium and kinetic constants varied with the level of salt were expressed as a function of salt concentration. 相似文献
940.
Viscosity, peel and shear strength of epoxidized natural rubber (ENR)-based pressure-sensitive adhesive was studied by using
hybrid tackifiers consisting of a mixture of coumarone-indene resin and petro resin. The coumarone-indene resin concentration
was fixed at 40 parts per hundred parts of rubber (phr). The concentration of petro resin, however, was varied from 20 to
80 phr. Toluene and polyethylene terephthalate (PET) film were used as the solvent and coating substrate respectively throughout
the experiment. Viscosity of adhesive was determined by a HAAKE Rotary Viscometer whereas peel and shear strength was measured
by a Lloyd Adhesion Tester. Results show that viscosity and shear strength decreases with increasing petro resin concentration.
However, peel strength exhibits a maximum value at 40 phr petro resin, an observation which is attributed to maximum wettability
and compatibility of adhesive on the substrate. ENR 25-based adhesive exhibits higher viscosity and peel strength but lower
shear strength compared to the ENR 50 adhesive system. 相似文献