全文获取类型
收费全文 | 18754篇 |
免费 | 189篇 |
国内免费 | 168篇 |
专业分类
安全科学 | 513篇 |
废物处理 | 750篇 |
环保管理 | 2524篇 |
综合类 | 2993篇 |
基础理论 | 4954篇 |
环境理论 | 6篇 |
污染及防治 | 5007篇 |
评价与监测 | 1227篇 |
社会与环境 | 1014篇 |
灾害及防治 | 123篇 |
出版年
2022年 | 194篇 |
2021年 | 225篇 |
2020年 | 149篇 |
2019年 | 185篇 |
2018年 | 318篇 |
2017年 | 313篇 |
2016年 | 462篇 |
2015年 | 307篇 |
2014年 | 457篇 |
2013年 | 1418篇 |
2012年 | 552篇 |
2011年 | 779篇 |
2010年 | 636篇 |
2009年 | 609篇 |
2008年 | 792篇 |
2007年 | 791篇 |
2006年 | 724篇 |
2005年 | 609篇 |
2004年 | 728篇 |
2003年 | 660篇 |
2002年 | 569篇 |
2001年 | 769篇 |
2000年 | 500篇 |
1999年 | 313篇 |
1998年 | 254篇 |
1997年 | 239篇 |
1996年 | 240篇 |
1995年 | 267篇 |
1994年 | 287篇 |
1993年 | 226篇 |
1992年 | 257篇 |
1991年 | 234篇 |
1990年 | 261篇 |
1989年 | 246篇 |
1988年 | 197篇 |
1987年 | 181篇 |
1986年 | 166篇 |
1985年 | 175篇 |
1984年 | 202篇 |
1983年 | 191篇 |
1982年 | 190篇 |
1981年 | 186篇 |
1980年 | 137篇 |
1979年 | 161篇 |
1978年 | 133篇 |
1977年 | 120篇 |
1975年 | 121篇 |
1974年 | 116篇 |
1973年 | 110篇 |
1972年 | 133篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
301.
302.
Val A. Catanzarite MD Ph.D. David B. Schrimmer Cynthia Maida Art Mendoza 《黑龙江环境通报》1995,15(3):229-235
The sinusoidal fetal heart rate pattern has been described in association with severe fetal anaemia, with fetal hypoxaemia, and with the administration of parenteral narcotics. Here, we report a case of decreased fetal movement in which a sinusoidal tracing was recorded. The sonographic diagnosis of a massive fetal intracranial haemorrhage was made. A non-interventive approach was taken and the fetus died soon after in utero. We review 28 previous cases in which the prenatal sonographic diagnosis of fetal intracranial haemorrhage was made, including the underlying maternal and fetal factors and neonatal outcomes. We propose that the sinusoidal tracing in this case was due to the intracranial bleed and suggest that fetal intracranial haemorrhage be considered in the sonographic evaluation of the fetus with a sinusoidal pattern. 相似文献
303.
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
304.
Christine Willekes Frans J. M. E. Roumen MD PhD Anne-Marie W. van Elsacker-Niele Harro T. Weiland Christl Vermey-Keers Johan H. J. M. van Krieken Christine E. M. de Die-Smulders Guus J. H. Hamers Gerrie P. M. Vaes-Peters 《黑龙江环境通报》1994,14(3):181-185
In a case of hydrops fetalis, serological examination showed a recent maternal human parvovirus B19 infection. Amniocentesis revealed a unique unbalanced translocation between chromosomes 3 and 11 of the fetus. The mother proved to have a balanced reciprocal translocation between chromosomes 3 and 11. A grossly macerated hydropic male fetus was delivered with a flat nose and low implanted deformed ears. Histopathological examination revealed nuclear inclusion bodies in fetal erythroid cells, confirming human parvovirus B19 infection. Parvovirus B19 DNA was demonstrated by in situ hybridization in the nuclei of heart muscle cells. Our finding of two different disorders in one case illustrates the importance of a complete evaluation of every case of hydrops fetalis, especially concerning counselling on the outcome of future pregnancies. The human parvovirus B19 infection will not recur due to the acquired immunity of the mother, whereas the balanced reciprocal translocation will endanger future pregnancies. 相似文献
305.
We describe a patient with a significantly elevated serum alphafetoprotein (AFP) concentration at 17 weeks of gestation, who showed only a marginally increased amniotic fluid AFP and lacked the second rapidly migrating band of acetylcholinesterase electrophoresis. Ultrasound examination revealed an encephalocele and ventriculomegaly. Autopsy showed that the encephalocele was not covered by skin. 相似文献
306.
307.
308.
The polymerase chain reaction (PCR) was used on material from a blighted ovum to confirm indirectly the carrier status of a woman with a family history of Becker muscular dystrophy. Conventional testing including creatine kinase levels, muscle biopsy, and EMG had been inconclusive, and on the basis of one elevated creatine kinase level, the woman had been designated a possible carrier. Ultrasound examination at 10 weeks of pregnancy indicated a blighted ovum, from which DNA was subsequently extracted and subjected to PCR testing for determination of sex and genotypic status with respect to the known familial deletion of the dystrophin gene. The blighted ovum was found to have a Y chromosome and also to be deleted for at least exon 6 of the dystrophin gene, indirectly indicating that the mother most likely carried the family mutation for Becker muscular dystrophy. 相似文献
309.
310.
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