全文获取类型
收费全文 | 16395篇 |
免费 | 173篇 |
国内免费 | 137篇 |
专业分类
安全科学 | 451篇 |
废物处理 | 628篇 |
环保管理 | 2291篇 |
综合类 | 2592篇 |
基础理论 | 4467篇 |
环境理论 | 4篇 |
污染及防治 | 4309篇 |
评价与监测 | 1005篇 |
社会与环境 | 855篇 |
灾害及防治 | 103篇 |
出版年
2022年 | 112篇 |
2021年 | 129篇 |
2020年 | 106篇 |
2019年 | 148篇 |
2018年 | 224篇 |
2017年 | 221篇 |
2016年 | 356篇 |
2015年 | 241篇 |
2014年 | 359篇 |
2013年 | 1275篇 |
2012年 | 441篇 |
2011年 | 632篇 |
2010年 | 536篇 |
2009年 | 519篇 |
2008年 | 689篇 |
2007年 | 692篇 |
2006年 | 661篇 |
2005年 | 508篇 |
2004年 | 587篇 |
2003年 | 522篇 |
2002年 | 482篇 |
2001年 | 705篇 |
2000年 | 471篇 |
1999年 | 284篇 |
1998年 | 241篇 |
1997年 | 218篇 |
1996年 | 227篇 |
1995年 | 249篇 |
1994年 | 273篇 |
1993年 | 220篇 |
1992年 | 247篇 |
1991年 | 222篇 |
1990年 | 254篇 |
1989年 | 238篇 |
1988年 | 193篇 |
1987年 | 175篇 |
1986年 | 158篇 |
1985年 | 169篇 |
1984年 | 192篇 |
1983年 | 180篇 |
1982年 | 187篇 |
1981年 | 179篇 |
1980年 | 137篇 |
1979年 | 153篇 |
1978年 | 131篇 |
1977年 | 118篇 |
1975年 | 118篇 |
1974年 | 115篇 |
1973年 | 110篇 |
1972年 | 134篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
281.
282.
This paper, based on the autonomy concept, continues to investigate hierarchical forms and spatial structure of ecosystems. The former can lead to limits for the selection of the component parts of an ecosystem and a distinction between its endogenous and exogenous variables; and the latter can be lead to a hypothesis of the space of an ecosystem: the space of an ecosystem = its habitat area + supporting area + impact area, and two characteristics of ecosystems, space-overlapping and the area of ecosystem space, have been further studied referring to human activities. 相似文献
283.
284.
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
285.
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
286.
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
287.
288.
289.
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
290.