全文获取类型
收费全文 | 89677篇 |
免费 | 1229篇 |
国内免费 | 1086篇 |
专业分类
安全科学 | 3713篇 |
废物处理 | 3271篇 |
环保管理 | 13801篇 |
综合类 | 21068篇 |
基础理论 | 26209篇 |
环境理论 | 71篇 |
污染及防治 | 14248篇 |
评价与监测 | 5392篇 |
社会与环境 | 3686篇 |
灾害及防治 | 533篇 |
出版年
2022年 | 776篇 |
2021年 | 802篇 |
2020年 | 648篇 |
2019年 | 860篇 |
2018年 | 1130篇 |
2017年 | 1179篇 |
2016年 | 2172篇 |
2015年 | 1838篇 |
2014年 | 2586篇 |
2013年 | 9255篇 |
2012年 | 2167篇 |
2011年 | 2411篇 |
2010年 | 3293篇 |
2009年 | 3378篇 |
2008年 | 1924篇 |
2007年 | 1764篇 |
2006年 | 2189篇 |
2005年 | 2192篇 |
2004年 | 2518篇 |
2003年 | 2341篇 |
2002年 | 1900篇 |
2001年 | 2223篇 |
2000年 | 1972篇 |
1999年 | 1489篇 |
1998年 | 1361篇 |
1997年 | 1351篇 |
1996年 | 1478篇 |
1995年 | 1566篇 |
1994年 | 1474篇 |
1993年 | 1331篇 |
1992年 | 1315篇 |
1991年 | 1289篇 |
1990年 | 1223篇 |
1989年 | 1214篇 |
1988年 | 1043篇 |
1987年 | 980篇 |
1986年 | 986篇 |
1985年 | 1055篇 |
1984年 | 1153篇 |
1983年 | 1162篇 |
1982年 | 1170篇 |
1981年 | 1091篇 |
1980年 | 942篇 |
1979年 | 917篇 |
1978年 | 820篇 |
1977年 | 714篇 |
1976年 | 637篇 |
1975年 | 601篇 |
1973年 | 629篇 |
1972年 | 634篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
S. N. Goroshkevich 《Russian Journal of Ecology》2008,39(3):168-175
A statistical analysis of interannual variation in a set of vegetative and generative characters over 13 years has been performed to characterize the growth and seed production dynamics of the Siberian stone pine (Pinus sibirica Du Tour) in the southeast of the forest zone in western Siberia. The results have shown that the range of fluctuations in most of vegetative characters is ordinary and their distribution is close to normal. The range of fluctuations in many generative characters is enormous (from 0 to +∞), and the distribution of their values is usually skewed, with low values being recorded several times more frequently than high values. Most variable are the proportion of abortive cones and other characters that are determined mainly in the spring of the pollination year. These characters account for a very high level of variation in the total seed production. 相似文献
73.
74.
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
75.
76.
77.
78.
79.
80.
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