全文获取类型
收费全文 | 91582篇 |
免费 | 1228篇 |
国内免费 | 1118篇 |
专业分类
安全科学 | 3715篇 |
废物处理 | 3349篇 |
环保管理 | 13987篇 |
综合类 | 21131篇 |
基础理论 | 26461篇 |
环境理论 | 74篇 |
污染及防治 | 15227篇 |
评价与监测 | 5531篇 |
社会与环境 | 3901篇 |
灾害及防治 | 552篇 |
出版年
2022年 | 781篇 |
2021年 | 818篇 |
2020年 | 657篇 |
2019年 | 867篇 |
2018年 | 1191篇 |
2017年 | 1206篇 |
2016年 | 2211篇 |
2015年 | 1840篇 |
2014年 | 2587篇 |
2013年 | 9260篇 |
2012年 | 2227篇 |
2011年 | 2515篇 |
2010年 | 3316篇 |
2009年 | 3413篇 |
2008年 | 2058篇 |
2007年 | 1950篇 |
2006年 | 2344篇 |
2005年 | 2310篇 |
2004年 | 2617篇 |
2003年 | 2468篇 |
2002年 | 2037篇 |
2001年 | 2414篇 |
2000年 | 2067篇 |
1999年 | 1539篇 |
1998年 | 1384篇 |
1997年 | 1363篇 |
1996年 | 1496篇 |
1995年 | 1580篇 |
1994年 | 1482篇 |
1993年 | 1334篇 |
1992年 | 1335篇 |
1991年 | 1298篇 |
1990年 | 1248篇 |
1989年 | 1218篇 |
1988年 | 1057篇 |
1987年 | 992篇 |
1986年 | 995篇 |
1985年 | 1060篇 |
1984年 | 1159篇 |
1983年 | 1169篇 |
1982年 | 1177篇 |
1981年 | 1095篇 |
1980年 | 944篇 |
1979年 | 928篇 |
1978年 | 823篇 |
1977年 | 720篇 |
1976年 | 638篇 |
1974年 | 605篇 |
1973年 | 634篇 |
1972年 | 632篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
81.
Molecular phylogeny and population structure of tideland snails in the genus Cerithidea around Japan
Phylogenetic relationships and genetic population structures were analyzed for tideland gastropods in the genus Cerithidea around Japan on the basis of partial sequence of the mitochondrial COI gene. Large genetic divergence was shown between individuals of Cerithidea cingulata in the southern Ryukyus and those in the central Ryukyus and the Japanese Islands. Haplotypes of C. cingulata from the Japanese Islands were paraphyletic with the exclusion of a monophyletic group from the central Ryukyus. Genetic differentiation of C. cingulata was also detected between Amami-Oshima Island and Okinawajima Island. No genetic divergence was found between Cerithidea rhizophorarum in the Japanese Islands and its subspecies C. rhizophorarum morchii in the Ryukyu Islands. The lack of genetic divergence of Cerithidea largillierti between continental China and Japan suggests relatively recent migration between the Japanese Islands and the Asian continent. For all three Cerithidea species distributed in both the Japanese Islands and the Ryukyu Islands, the Tokara Gap and the Kerama Gap were shown to have acted as barriers to the dispersal. 相似文献
82.
83.
84.
85.
86.
87.
88.
Schaefer CE do Amaral EF de Mendonça BA Oliveira H Lani JL Costa LM Fernandes Filho EI 《Environmental monitoring and assessment》2008,140(1-3):279-289
The relationships between soils attributes, soil carbon stocks and vegetation carbon stocks are poorly know in Amazonia, even
at regional scale. In this paper, we used the large and reliable soil database from Western Amazonia obtained from the RADAMBRASIL
project and recent estimates of vegetation biomass to investigate some environmental relationships, quantifying C stocks of
intact ecosystem in Western Amazonia. The results allowed separating the western Amazonia into 6 sectors, called pedo-zones:
Roraima, Rio Negro Basin, Tertiary Plateaux of the Amazon, Javari-Juruá-Purus lowland, Acre Basin and Rondonia uplands. The
highest C stock for the whole soil is observed in the Acre and in the Rio Negro sectors. In the former, this is due to the
high nutrient status and high clay activity, whereas in the latter, it is attributed to a downward carbon movement attributed
to widespread podzolization and arenization, forming spodic horizons. The youthful nature of shallow soils of the Javari-Juruá-Purus
lowlands, associated with high Al, results in a high phytomass C/soil C ratio. A similar trend was observed for the shallow
soils from the Roraima and Rondonia highlands. A consistent east–west decline in biomass carbon in the Rio Negro Basin sector
is associated with increasing rainfall and higher sand amounts. It is related to lesser C protection and greater C loss of
sandy soils, subjected to active chemical leaching and widespread podzolization. Also, these soils possess lower cation exchangeable
capacity and lower water retention capacity. Zones where deeply weathered Latosols dominate have a overall pattern of high
C sequestration, and greater than the shallower soils from the upper Amazon, west of Madeira and Negro rivers. This was attributed
to deeper incorporation of carbon in these clayey and highly pedo-bioturbated soils. The results highlight the urgent need
for refining soil data at an appropriate scale for C stocks calculations purposes in Amazonia. There is a risk of misinterpreting
C stocks in Amazonia when such great pedological variability is not taken into account. 相似文献
89.
Greg R. J. Sutherland Joachim Haselbach Steven D. Aust 《Environmental science and pollution research international》1997,4(1):16-20
Two synthetic superabsorbent crosslinked acrylic polymers were mineralized by the white-rot fungusPhanerochaete chrysosporium. The amount of polymer converted to CO2 increased as the amount of polymer added to the cultures increased. In the presence of sufficiently large amounts of the superabsorbents, such that all of the culture fluid was absorbed and a gelatinous matrix was formed, the fungus still grew and mineralization was observed. Neither the polymers, nor their degradation products were toxic to the fungus. While the rates of mineralization were low, all of the polymers incubated in the liquid fungal cultures were completely depolymerized to water soluble products within 15–18 days. The depolymerization of the polymers was observed only in nitrogen limited cultures of the fungus which secrete the lignin degradation system, however, the water soluble products of depolymerization were mineralized in both nutrient limited and sufficient cultures of the fungus. The rate of mineralization of the depolymerized metabolites was more than two times greater in nutrient sufficient cultures. Following longer incubation periods, most (> 80 %) of the radioactivity was recovered in the fungal mycelial mat suggesting that carbon of the polymer had been converted to fungal metabolites. 相似文献
90.
We examined the impact of seven species of mobile mushroom corals (Fungiidae) on the community structure of sheltered reef slopes in terms of their patterns of migration, habitat use and competition with other benthic organisms. On fringing reefs at Eilat, Red Sea, polyps detached at 1 to 6 cm length, and grew to 11–55 cm length. Attached mushroom corals were oriented vertically in reef cavities. Detached corals migrated downward on the reef slope and onto rubble or soft substratum at the reef base, at 29 to 71 cmyr–1. Mobility decreased with corallum size and extent of undersurface ornamentation. In aquaria, small corals righted themselves and migrated up to 6 cm d–1 by nocturnally inflating and pushing their tissues against the substratum. Autonomous coral behavior and storm-generated water motion appeared to account for most fungiid mobility at Eilat. Mushroom corals did not damage each other upon contact, even in multi-species aggregations, but unilaterally damaged non-fungiid scleractinian corals. Their dominance during contact interactions retards overgrowth by larger attached scleractinians, and mobility allows them to colonize soft substrata not accessible to most other reef corals. 相似文献