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排序方式: 共有134条查询结果,搜索用时 15 毫秒
121.
在pH10.4~11.1碱性溶液中钙离子与紫尿酸铵生成橙红色的稳定络合物.络合物最大吸收峰为500nm,显色后络合物可稳定2时.钙量在2.50~25.0(μg/50ml)范围内符合比耳定律,表观摩尔吸光系数为1.2×10~4L/mol·cm.桑德尔灵敏度为0.003μg/cm~2,方法加标回收率为94%~104%. 相似文献
122.
对离子色谱法测定水中钙离子的不确定度进行评定,并分析了其影响因素主要有来自重复测量引入的A类不确定度和来自工作曲线的不确定度以及来自标准溶液的不确定度。 相似文献
123.
悬浮液进样火焰原子吸收光谱法测定环境样品中钙、镁 总被引:1,自引:0,他引:1
将环境样品制成悬浮液,用空气/乙炔火焰原子吸收光谱法测定钙、镁、以三氯化镧、丙三醇和高氯酸为混合抗干扰剂,有效消除了环境样品中铅、磷、硫、硅等共存元素的干扰,其中丙三醇不仅是抗干扰剂,而且还起着稳定剂的作用,进一步简化了测定步骤,有效提高了分析速度。本文通过水溶液标准曲线校正,使测定更加方便。对测定结果与湿法消化法比较,具有较好的相关性。本法简便、快速、测定分析结果准确可靠。 相似文献
124.
以Al2O3和CaCO3为原料用焙烧酸溶制备工艺合成新型高效的聚合氯化铝钙,研究结果表明,提高焙烧温度,原料配比为(Al2O3)70%,酸溶时间为3h,酸用量为(20g原料)70mL时有利于新型絮凝剂制备合成反应。并以本钢转炉煤气洗涤废水为处理对象研究混凝效能。结果表明,新工艺制备的聚合氯化铝钙混凝效能优于工业聚铝。 相似文献
125.
F. P. Sival A. P. Grootjans P. J. Stuyfzand T. Verschoore de la Houssaye 《Journal of Coastal Conservation》1997,3(1):79-86
Basiphilous, open, species-rich vegetation types of young dune slacks have declined throughout Europe in recent years, and
have largely been replaced by often acidophilous, tall marsh and scrub vegetation. This succession appears to be accelerated
by a decrease in the discharge of calcareous groundwater from sandy ridges or small dune hummocks. The present study deals
with spatial and temporal variation in the chemical composition of the groundwater in the upper metres of the soil of a degraded
dune slack complex on the Dutch barrier island of Schiermonnikoog, with emphasis on (1) groundwater composition, (2) water
level and (3) decalcification patterns. The main aim was to assess perspectives for restoring basiphilous vegetation types
which had been abundant in this slack from 1954 to 1977. The depth of decalcification was related to former hydrological conditions
along a transect of 200 m. Acidifying effects of rainfall were reflected in the chemical composition of the groundwater below
small dune hummocks within the slack. Distinct precipitation water lenses, poor in dissolved ions, were formed under the dune
hummocks during a wet period. This microtopography did not contribute to the discharge of calcareous groundwater to lowlying
parts of the slack. Here, groundwater showed decreasing concentrations of the dissolved ions after a rain shower. Except for
the peripheral sections of the slack—where upward seepage of groundwater (exfiltration)still occurs—infiltration conditions
are now dominant in the slack. The consequences of the present hydrological conditions for restoration are briefly discussed. 相似文献
126.
Calcium concentrations were measured in supernatant amniotic fluid in order to establish whether they may be used as a marker for cystic fibrosis. No difference in values were found, whether the sample was derived from a normal pregnancy or from a pregnancy which resulted in a baby affected with cystic fibrosis. 相似文献
127.
中小型印染厂废水处理方法研究 总被引:3,自引:0,他引:3
介绍了利用自制的混凝剂与电石渣联用处理印染废水的一种新方法,该方法工艺流程简单,投资少,运行费用低,易于操作,CODcr去除率高,为中小型印染厂废水治理开辟一条新的途径. 相似文献
128.
Base cation depletion, eutrophication and acidification of species-rich grasslands in response to long-term simulated nitrogen deposition 总被引:2,自引:0,他引:2
Horswill P O'Sullivan O Phoenix GK Lee JA Leake JR 《Environmental pollution (Barking, Essex : 1987)》2008,155(2):336-349
Pollutant nitrogen deposition effects on soil and foliar element concentrations were investigated in acidic and limestone grasslands, located in one of the most nitrogen and acid rain polluted regions of the UK, using plots treated for 8-10years with 35-140kg Nha(-2)y(-1) as NH(4)NO(3). Historic data suggests both grasslands have acidified over the past 50years. Nitrogen deposition treatments caused the grassland soils to lose 23-35% of their total available bases (Ca, Mg, K, and Na) and they became acidified by 0.2-0.4 pH units. Aluminium, iron and manganese were mobilised and taken up by limestone grassland forbs and were translocated down the acid grassland soil. Mineral nitrogen availability increased in both grasslands and many species showed foliar N enrichment. This study provides the first definitive evidence that nitrogen deposition depletes base cations from grassland soils. The resulting acidification, metal mobilisation and eutrophication are implicated in driving floristic changes. 相似文献
129.
The effect of selenium on the vegetative reproduction of cultured Lemna minor was investigated. Cultures were grown for 28 days at a temperature of 23 ± 3°C and under a constant (24 h) light cycle. Growth was monitored every seven days. The growth of L. minor was inhibited at high concentrations (>5mg/L [Se]), but stimulated at low concentrations (0.2—2mg/L [Se]). This stimulation of growth at low selenium concentrations has significant implications for the use of selenium enriched superphosphate fertilisers on selenium deficient pastures. 相似文献
130.
Mercury (Hg) contents in ten chemical fertilizers were determined, and the e ect of calcium superphosphate (CSP) on the uptake
and translocation of Hg in corn seedlings was investigated by pot experiments. CSP was applied at the levels of 0, 66.7, and 133.4 mg
P2O5/kg to Hg-treated (2 mg/kg) and untreated soils. CSP had the highest Hg content (5.1 mg/kg), followed by the NPK compound
fertilizer 15-5-5 (15% N, 5% P2O5, 5% K2O) (1.2 mg/kg), then by nitrogen fertilizers (except for ammonia sulfate) and potassium
fertilizers. Application of CSP did not obviously influence the biomass of corn roots, but it significantly increased the biomass of corn
shoots in Hg-treated soil. Application of CSP at the levels of 66.7 and 133.4 mg P2O5/kg did not obviously influence the uptake of Hg
by corn seedlings on soils without Hg treatment, but it decreased the Hg uptake of corn seedlings significantly on Hg-treated soils. The
transfer coe cient of Hg in corn seedlings improved slightly on soils without Hg treatment, but decreased slightly on Hg-treated soils
with the application of CSP. These results implied that CSP could ameliorate Hg toxicity to corn seedlings by inhibiting the uptake and
the translocation of Hg in plants on Hg-polluted soils. 相似文献