全文获取类型
收费全文 | 37967篇 |
免费 | 479篇 |
国内免费 | 338篇 |
专业分类
安全科学 | 1093篇 |
废物处理 | 1708篇 |
环保管理 | 4842篇 |
综合类 | 5509篇 |
基础理论 | 10056篇 |
环境理论 | 13篇 |
污染及防治 | 10263篇 |
评价与监测 | 2723篇 |
社会与环境 | 2293篇 |
灾害及防治 | 284篇 |
出版年
2023年 | 186篇 |
2022年 | 403篇 |
2021年 | 436篇 |
2020年 | 291篇 |
2019年 | 381篇 |
2018年 | 689篇 |
2017年 | 687篇 |
2016年 | 1032篇 |
2015年 | 731篇 |
2014年 | 1095篇 |
2013年 | 3221篇 |
2012年 | 1292篇 |
2011年 | 1666篇 |
2010年 | 1437篇 |
2009年 | 1349篇 |
2008年 | 1705篇 |
2007年 | 1759篇 |
2006年 | 1597篇 |
2005年 | 1263篇 |
2004年 | 1319篇 |
2003年 | 1216篇 |
2002年 | 1156篇 |
2001年 | 1508篇 |
2000年 | 1010篇 |
1999年 | 649篇 |
1998年 | 487篇 |
1997年 | 433篇 |
1996年 | 477篇 |
1995年 | 496篇 |
1994年 | 493篇 |
1993年 | 431篇 |
1992年 | 452篇 |
1991年 | 407篇 |
1990年 | 434篇 |
1989年 | 416篇 |
1988年 | 371篇 |
1987年 | 321篇 |
1986年 | 284篇 |
1985年 | 287篇 |
1984年 | 346篇 |
1983年 | 326篇 |
1982年 | 360篇 |
1981年 | 291篇 |
1980年 | 241篇 |
1979年 | 286篇 |
1978年 | 241篇 |
1977年 | 212篇 |
1975年 | 192篇 |
1974年 | 193篇 |
1972年 | 200篇 |
排序方式: 共有10000条查询结果,搜索用时 84 毫秒
371.
J. H. A. M. Tuerlings MD A. S. P. M. Breed R. Vosters G. J. P. A. Anders 《黑龙江环境通报》1993,13(4):301-306
A 70,XXX, +18 karyotype was found by chorionic villus sampling, while the fetal fibroblast culture of the affected fetus revealed a 47,XX,+ 18 karyotype. From several possible mechanisms, we assume that a second gamete fusion occurred after the first cell division of the zygote. According to this interpretation, the mosaicism arose in very early pregnancy (at the two-cell stage). This discrepancy can therefore be explained by selection pressure, due to the differentiation processes in the embryonic tissues. 相似文献
372.
Dr Claire Julian-Reynier Genevieve Macquart-Moulin Jean-Paul Moatti Anderson Loundou Yvette Aurran Françoise Chabal Ségolene Aymé 《黑龙江环境通报》1993,13(7):613-627
The objective of this study was to explore women's attitudes towards prenatal diagnosis of trisomy 21 and to examine some of the factors possibly responsible for these attitudes before implementing in real practice serological screening of pregnant women at risk for trisomy 21. We carried out a telephone survey on a representative sample of women who had recently had a normal livebirth delivery in the Marseille district in 1990. The participation rate was 80 per cent and the average age of the mothers was 28-9 years. Among the 514 women interviewed, 78 per cent stated that they would ask for an amniocentesis for a 1 per cent risk of trisomy 21 at their next pregnancy. When adjusting for confounding factors, the decision to have or not to have an amniocentesis was found to depend not only on the women's attitude towards induced abortion, but also on their understanding of the risk involved and on the social context (knowing a handicapped child, discussion with the father). It also depended on the women's age and on what they knew about amniocentesis from the medical point of view. The risk of miscarriage can influence a woman's choice but this objection was not found to affect the women's decisions significantly in our survey. The data showed the existence of a high potential demand for fetal karyotyping. 相似文献
373.
374.
375.
376.
377.
378.
Cynthia J. Sims MD Don T. Fujito Dennis R. Burholt Josef Dadok Harlan R. Giles D. Allan Wilkinson 《黑龙江环境通报》1993,13(6):473-480
We have investigated the ability of high-resolution proton NMR spectroscopy to provide a biochemical constituent screening of human amniotic fluid (AF). Proton NMR spectra were obtained at 300 MHz on AF from patients undergoing amniocentesis in the mid-trimester. Only AF from normal pregnancies (normal fetal karyotype, normal a-fetoprotein levels, normal birth outcome) was used in this study. The AF supernatant was lyophilized and resuspended in deuterated water containing 0.1 mm phosphate buffer and 6.02 mm disodium maleate. Identification of low molecular weight compounds was confirmed by two-dimensional NMR spectra (primarily correlated spectroscopy, or COSY) and standard addition techniques. A broad profile of compounds were ‘NMR visible’ in a single proton spectrum, including creatinine, glucose, organic acids (acetate, citrate, and lactate) and several amino acids (alanine, histidine, leucine, phenylalanine, tyrosine and valine). The proton spectrum was unaffected by prior freezing/thawing of AF samples. We were able to quantify compounds by comparison with an added concentration standard (maleate) at concentrations as low as 30 μm. Good agreement with literature values based on other analytical techniques was obtained. 相似文献
379.
380.