全文获取类型
收费全文 | 665篇 |
免费 | 12篇 |
国内免费 | 8篇 |
专业分类
安全科学 | 24篇 |
废物处理 | 48篇 |
环保管理 | 31篇 |
综合类 | 126篇 |
基础理论 | 149篇 |
环境理论 | 1篇 |
污染及防治 | 192篇 |
评价与监测 | 82篇 |
社会与环境 | 25篇 |
灾害及防治 | 7篇 |
出版年
2023年 | 12篇 |
2022年 | 24篇 |
2021年 | 21篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 34篇 |
2017年 | 27篇 |
2016年 | 41篇 |
2015年 | 22篇 |
2014年 | 44篇 |
2013年 | 75篇 |
2012年 | 42篇 |
2011年 | 45篇 |
2010年 | 37篇 |
2009年 | 23篇 |
2008年 | 16篇 |
2007年 | 19篇 |
2006年 | 20篇 |
2005年 | 10篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 23篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1997年 | 4篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1986年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 6篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1967年 | 4篇 |
1966年 | 3篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1960年 | 4篇 |
1959年 | 4篇 |
1958年 | 10篇 |
1957年 | 4篇 |
1956年 | 3篇 |
1955年 | 1篇 |
1931年 | 1篇 |
1930年 | 2篇 |
排序方式: 共有685条查询结果,搜索用时 15 毫秒
271.
272.
273.
274.
275.
Adsorption kinetics of methyl violet onto perlite 总被引:11,自引:0,他引:11
This study examines adsorption kinetics and activation parameters of methyl violet on perlite. The effect of process parameters like contact time, concentration of dye, temperature and pH on the extent of methyl violet adsorption from solution has been investigated. Results of the kinetic studies show that the adsorption reaction is first order with respect to dye solution concentration with activation energy of 13.2 kJ mol(-1). This low activation energy value indicates that the adsorption reaction is diffusion controlled. The activation parameters using Arrhenius and Eyring equations have been calculated. Adsorption increases with increase of variables such as contact time, initial dye concentration, temperature and pH. 相似文献
276.
In the period from 1980 to 1984 organic phosphorus, nutrients, primary production rates (14C), chlorophyll a (chl a) standing crops, and basic oceanographic parameters were measured during 23 cruises at six stations in the open waters of the northern Adriatic Sea. These waters are significantly influenced by polluted Po River discharge. Organic phosphorus was correlated with several parameters which characterize phytoplankton activity and organic matter decomposition processes. In the late winter-spring period, organic phosphorus is produced during phytoplankton blooms. It is hypothesized that microzooplankton grazing is the main factor increasing the organic phosphorus concentrations in summer (up to 1.1 mol 1-1). Fall and winter had much lower values (below 0.3 mol 1-1) due to remineralization processes and an increased water mass exchange between the northern and central Adriatic regions. The direct contribution of organic phosphorus by freshwater discharge was not found to be significant. The higher organic phosphorus concentrations that can occur in low salinity waters are most likely due to their increased capability to support primary production. 相似文献
277.
The reproductive season of the Adelomelon brasiliana population of Mar del Plata extends from September to April (austral spring and summer), showing synchronisation with water temperature. Adult gonad state is related to shell-free wet mass. Oocytes reach 200 m in diameter before spawning. In autumn, a resting phase begins, when no new oocytes develop and the non-spawned ones undergo reabsorption. Gonadic development begins during the early winter, when new previtellogenic oocytes can be observed through histology. The long reproductive season would increase the ability of the species to recover from harvesting.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
278.
The relationship between somatic growth and growth of otoliths of sea bass larvae, postlarvae and juveniles under relatively steady temperature conditions was studied. Larvae were incubated at the constant ambient temperature of 13.5°C, whereas postlarvae and juveniles were reared at a comparatively steady temperature ranging from 18.6 to 20.4°C, with a mean of 19.67°C. The patterns of both somatic and otolith growth were found to be similar. Differentiated data on larvae length and otolith diameters indicated three periods of change in their growth rates. Since temperature was kept relatively steady during the experiment, and larvae fed ad libitum, these periods could be attributed with relative certainty to intrinsic changes which occur during stage-specific periods of growth. The third period of change in both growth rates indicates a specific phase of growth during metamorphosis. The changes in growth rates, as well as the raw time series of the growth of both larval lengths and otolith diameters, may be described by higher order polynomials with a high degree of probability levels. A non-linear relationship between body length and otolith diameters was established, indicating positive allometric growth of otoliths. It was also observed that the coefficient of allometric growth changed at the time estimated for the end of metamorphosis. Thus, a non-linear relationship and changes in the coefficients of allometry should be borne in mind when back-calculating somatic growth from the growth of otoliths. 相似文献
279.
M. Peharda C. A. Richardson I. Mladineo S. Šestanović Z. Popović J. Bolotin N. Vrgoč 《Marine Biology》2007,151(2):629-638
Age, growth and population structure of Modiolus barbatus from Mali Ston Bay, Croatia were determined using modal size (age) classes in length frequency distributions, annual pallial
line scars on the inner shell surface, internal annual growth lines in shell sections of the middle nacreous layer and Calcein
marked and transplanted mussels. The length frequency distributions indicated that M. barbatus attain a length of ∼40 mm in 5–6 years indicating that a large proportion of the population in Mali Ston Bay is <5 years
old. Some mussels of ∼60 mm were predicted to be 14 years old using the Von Bertalanffy growth (VBG) equation. Up to the first
6 pallial line scars were visible in young (<6 years) mussels but in older shells the first scars became obscured by nacre
deposition as the mussel increased in length and age. The age of the older shells (>6 years) was determined from the middle
nacreous lines in shell section, which formed annually in winter between February and March; the wider dark increments forming
during summer (June to September). The oldest mussel, determined from the middle nacreous lines, was >12 years, with the majority
of mussels aged between 3 and 6 years of age. The ages of mussels ascertained using the growth lines were not dissimilar to
the ages predicted from the length frequency distributions. Age at length curves produced using modal size class data were
not different from the data obtained using the pallial scar rings and internal growth lines. Taken together these data suggest
that M. barbatus attains a length of 40 and 50 mm within 5 and 8 years, respectively. Eighty one percent of individual M. barbatus injected with a Calcein seawater solution (300 mg Calcein l−1), into their mantle cavity successfully deposited a fluorescent line, which was visible in suitably prepared shell sections
under ultra violet light. Incorporation of Calcein into the mussel shells was seasonally variable with the lowest frequency
of incorporation in mussels marked in February and recovered in May. Seasonal shell growth was observed with significantly
higher growth rates in mussels marked in May and removed in August (ANCOVA, F
3,149 = 23.11, P < 0.001). Mussels (∼18 to 22 mm) marked in May and recovered in August displayed maximal growth rates of >2.5 mm month−1 compared with a mean mussel growth rate of 1.2 ± 0.6 mm month−1. At other times of the year mussel shell growth ranged from immeasurable to 1.48 mm month−1. 相似文献
280.
本文研究了在自然状况下污水塘的净化作用及其效率,通过对总氮、总磷、COD_(Cr)和BOD_5等在进、出水中的含量与水温进行回归分析,建立了三者之间的相关性方程。同时讨论了水温对污水塘的自净效率的影响。 相似文献