全文获取类型
收费全文 | 33786篇 |
免费 | 338篇 |
国内免费 | 246篇 |
专业分类
安全科学 | 1001篇 |
废物处理 | 1655篇 |
环保管理 | 4522篇 |
综合类 | 4873篇 |
基础理论 | 9257篇 |
环境理论 | 8篇 |
污染及防治 | 7838篇 |
评价与监测 | 2421篇 |
社会与环境 | 2615篇 |
灾害及防治 | 180篇 |
出版年
2023年 | 132篇 |
2022年 | 264篇 |
2021年 | 319篇 |
2020年 | 195篇 |
2019年 | 243篇 |
2018年 | 847篇 |
2017年 | 850篇 |
2016年 | 1066篇 |
2015年 | 564篇 |
2014年 | 862篇 |
2013年 | 2471篇 |
2012年 | 1197篇 |
2011年 | 1925篇 |
2010年 | 1419篇 |
2009年 | 1503篇 |
2008年 | 1865篇 |
2007年 | 1956篇 |
2006年 | 1208篇 |
2005年 | 1131篇 |
2004年 | 1063篇 |
2003年 | 1075篇 |
2002年 | 1048篇 |
2001年 | 1107篇 |
2000年 | 778篇 |
1999年 | 486篇 |
1998年 | 381篇 |
1997年 | 383篇 |
1996年 | 397篇 |
1995年 | 466篇 |
1994年 | 395篇 |
1993年 | 344篇 |
1992年 | 376篇 |
1991年 | 356篇 |
1990年 | 326篇 |
1989年 | 322篇 |
1988年 | 295篇 |
1987年 | 241篇 |
1986年 | 247篇 |
1985年 | 248篇 |
1984年 | 277篇 |
1983年 | 257篇 |
1982年 | 269篇 |
1981年 | 221篇 |
1980年 | 165篇 |
1979年 | 181篇 |
1978年 | 163篇 |
1977年 | 133篇 |
1975年 | 137篇 |
1973年 | 167篇 |
1972年 | 142篇 |
排序方式: 共有10000条查询结果,搜索用时 534 毫秒
461.
A protocol for easy storage and later expansion of lymphocyte populations is given. Compared with methods using transformed cell lines, the method has a number of advantages for repeated production of cells for the isolation of DNA in amounts sufficient for use in diagnostic DNA technology. 相似文献
462.
463.
The “Linh Duong” (Pseudonovibos spiralis), a newly described Vietnamese bovid, has been shown to be related to the Caprinae on the basis of the mitochondrial cytochrome
b gene sequencing from horn fragments. To integrate the greatest available biodiversity we performed a new phylogenetic analysis
including all genera of Caprinae. Unexpectedly, Pseudonovibos is found to be robustly associated with Rupicapra, and closer to the Alpine than to the Pyrenean chamois. Several clues led us to interpret this result as a carry-over DNA
contamination of Pseudonovibos by Rupicapra.
Received: 19 July 1999 / Accepted in revised form: 20 October 1999 相似文献
464.
465.
H. Brandenburg MD W. De Koning M. G. J. Jahoda Th. Stijnen M. A. J. De Ridder E. S. Sachs J. W. Wladimiroff 《黑龙江环境通报》1992,12(12):1031-1035
One hundred and fifty-one women of advanced maternal age who underwent genetic termination of pregnancy (TOP) were studied for their reproductive behaviour and the type of procedure for prenatal diagnosis in a subsequent pregnancy. A total of 59 women (39 per cent) had a further pregnancy. In all continuing pregnancies prenatal diagnosis was performed, of which 75 per cent consisted of chorionic villus sampling (CVS). Reproductive behaviour following a genetic termination was negatively correlated with maternal age and parity. Both reproductive behaviour and the choice to undergo a diagnostic procedure in the next pregnancy were independent of the type of diagnostic procedure in the previous affected pregnancy. 相似文献
466.
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
467.
468.
469.
I. Shagina H. L. Dadali V. P. Sitnikov V. V. Pugachev N. A. Malygina O. V. Evgrafov 《黑龙江环境通报》1995,15(1):27-34
Ninety-two families with spinal muscular atrophy (SMA) applied for genetic counselling and further prenatal diagnosis. To minimize expenses, only one tightly linked informative marker was determined in the course of preliminary examination, and non-radioactive allele detection was preferably used. Four prenatal diagnoses of SMA type I, four of SMA type II, and one of SMA type III were made. This trial programme shows the considerable requirements, importance, and potential effectiveness of prenatal prediction of SMA in Russia. 相似文献
470.
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