全文获取类型
收费全文 | 4586篇 |
免费 | 99篇 |
国内免费 | 51篇 |
专业分类
安全科学 | 174篇 |
废物处理 | 168篇 |
环保管理 | 737篇 |
综合类 | 800篇 |
基础理论 | 1085篇 |
环境理论 | 10篇 |
污染及防治 | 1135篇 |
评价与监测 | 334篇 |
社会与环境 | 226篇 |
灾害及防治 | 67篇 |
出版年
2023年 | 23篇 |
2022年 | 33篇 |
2021年 | 68篇 |
2020年 | 37篇 |
2019年 | 49篇 |
2018年 | 117篇 |
2017年 | 125篇 |
2016年 | 127篇 |
2015年 | 115篇 |
2014年 | 153篇 |
2013年 | 334篇 |
2012年 | 200篇 |
2011年 | 281篇 |
2010年 | 202篇 |
2009年 | 224篇 |
2008年 | 242篇 |
2007年 | 272篇 |
2006年 | 253篇 |
2005年 | 202篇 |
2004年 | 167篇 |
2003年 | 169篇 |
2002年 | 165篇 |
2001年 | 118篇 |
2000年 | 90篇 |
1999年 | 74篇 |
1998年 | 66篇 |
1997年 | 72篇 |
1996年 | 51篇 |
1995年 | 66篇 |
1994年 | 59篇 |
1993年 | 43篇 |
1992年 | 47篇 |
1991年 | 26篇 |
1990年 | 27篇 |
1989年 | 17篇 |
1988年 | 20篇 |
1987年 | 16篇 |
1986年 | 24篇 |
1985年 | 26篇 |
1984年 | 23篇 |
1983年 | 28篇 |
1982年 | 25篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 22篇 |
1978年 | 14篇 |
1977年 | 11篇 |
1965年 | 11篇 |
1962年 | 12篇 |
1957年 | 11篇 |
排序方式: 共有4736条查询结果,搜索用时 132 毫秒
61.
B. Sikkema-Raddatz R. H. Sijmons M. B. Tan-Sindhunata A. Y. Van Der Veen R. Brunsting B. De Vries J. R. Beekhuis D. J. Bekedam B. Van Aken B. De Jong 《黑龙江环境通报》1995,15(5):467-473
We report two cases of apparently balanced complex de novo chromosomal rearrangements (BCCR) detected prenatally at 17 weeks and 10 weeks of gestation, respectively. Chromosomes were studied using GTG-banding and fluorescent in situ hybridization (FISH). In one case four chromosomes and in the other case three chromosomes were involved in the rearrangements. One of the pregnancies was terminated and no external or internal abnormalities were detected at autopsy. The other pregnancy continued to term. Level III ultrasound examination showed no abnormalities. The child is now 3 years old and has neither congenital anomalies nor evidence of delayed psychomotor development. 相似文献
62.
Frans J. Los MD PhD Diane Van Opstal Martin P. Schol Johannes L. J. Gaillard Helen Brandenburg Ans M. W. Van Den Ouweland Peter A. In 'T Veld 《黑龙江环境通报》1995,15(12):1155-1159
A prenatally detected case of a rare mosaic tetrasomy 12p/trisomy 12p is reported, presenting as the well-known accessory isochromosome 12p and a supernumerary single 12p marker in 17/24 and 6/24 clones of cultured amniotic fluid cells, respectively. The chromosomal nature of both marker chromosomes was investigated in cultured amniotic fluid cells by fluorescent in situ hybridization with various probes: the 12-centromeric probes pa12H8 and D12Z3, a whole chromosome 12 paint, and the chromosome 12p-specific paint M28. DNA analysis revealed a maternal origin of the extra 12p material. After counselling, the parents requested termination of pregnancy. Inspection and autopsy of the fetus revealed many of the dysmorphisms and internal structural abnormalities of the Pallister–Killian syndrome. 相似文献
63.
A Framework for Monitoring and Evaluating Carbon Mitigation by Farm Forestry Projects: Example of a Demonstration Project in Chiapas,Mexico 总被引:1,自引:0,他引:1
De Jong Ben H.J. Tipper Richard Taylor John 《Mitigation and Adaptation Strategies for Global Change》1997,2(2-3):231-246
Mitigation and Adaptation Strategies for Global Change - In Mexico an estimated 4.5 × 106ha are available for farm forestry, while up to 6.1 × 106 ha could be saved from deforestation by... 相似文献
64.
Baisen Zhang Ian Valentine Peter D. Kemp 《Agriculture, ecosystems & environment》2005,110(3-4):279-288
Decision tree, one of the data mining approaches, was used to model the relative abundance of five functional groups of plant species, namely high fertility response grasses (HFRG), low fertility tolerance grasses (LFTG), legume, moss and flatweeds in a New Zealand hill-pasture ecosystem using aboveground biomass. The model outputs were integrated with a geographic information system (GIS) to map and validate the predictions on a pasture. The decision tree models clearly revealed the interactions between the functional groups and environmental and management factors, and also indicated the relative importance of these factors in influencing the functional group abundance. Soil Olsen P was the most significant factor influencing the abundance of LFTG and moss, while soil bulk density, slope and annual P fertiliser input were the most significant factors influencing the abundance of legume, HFRG and flatweeds, respectively. Generally, slope and soil Olsen P were the two key factors underlying the patterns of abundance for these five functional groups. For the five functional groups studied, there was an overall predictive accuracy of 75%. Modelling functional group abundance simplified the investigation of the complex interrelationship between species and environment in a pasture ecosystem. The integration of the decision tree with GIS in this study provides a platform to investigate community structure and functional composition for a pasture over space, and thus can be applied as a tool in pasture management. 相似文献
65.
M. Van Blerk MD J. Smitz L. De Catte C. Kumps J. Van Der Elst A. C. Van Steirteghem 《黑龙江环境通报》1992,12(12):1062-1066
This study explores if assay of cancer antigen 125 (CA 125) in maternal serum might aid the detection of Down's syndrome in the second trimester of pregnancy. CA 125 levels were determined retrospectively in stored maternal serum samples from ten Down's syndrome pregnancies and 78 controls matched for gestational and maternal age. In addition, second-trimester amniotic fluid samples from nine Down's syndrome and 109 unaffected pregnancies were analysed for CA 125. Maternal serum CA 125 values for Down's syndrome pregnancies were lower, with the median being 0.72 multiples of the unaffected population median. The medians for affected and unaffected pregnancies did not differ significantly and there was a considerable overlap in the range of values of cases and controls. The distribution of amniotic fluid CA 125 levels for Down's syndrome pregnancies resembled that for controls. From our present results, we could not find an association between Down's syndrome and second-trimester maternal serum or amniotic fluid CA 125 levels. 相似文献
66.
67.
Although amphibians are highly vocal, they generally emit only a limited number of acoustic communication signals. We report here the extraordinarily rich vocal repertoire of Amolops tormotus, a ranid species in China. These frogs produce countless vocalizations, some of which share features of birdsong or primate calls, e.g., ultrasonic frequency components, multiple upward and downward FM sweeps, and sudden onset and offset of selective harmonic components within a call note. Frame-by-frame video analysis of the frog's calling behavior suggests the presence of two pairs of vocal sacs that may contribute to the remarkable call-note complexity in this species. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00114-002-0335-x. 相似文献
68.
69.
70.