全文获取类型
收费全文 | 36994篇 |
免费 | 388篇 |
国内免费 | 271篇 |
专业分类
安全科学 | 924篇 |
废物处理 | 1501篇 |
环保管理 | 4666篇 |
综合类 | 7217篇 |
基础理论 | 9912篇 |
环境理论 | 15篇 |
污染及防治 | 9238篇 |
评价与监测 | 2256篇 |
社会与环境 | 1683篇 |
灾害及防治 | 241篇 |
出版年
2022年 | 266篇 |
2021年 | 275篇 |
2019年 | 277篇 |
2018年 | 493篇 |
2017年 | 475篇 |
2016年 | 751篇 |
2015年 | 547篇 |
2014年 | 835篇 |
2013年 | 2742篇 |
2012年 | 1029篇 |
2011年 | 1400篇 |
2010年 | 1190篇 |
2009年 | 1178篇 |
2008年 | 1490篇 |
2007年 | 1533篇 |
2006年 | 1389篇 |
2005年 | 1131篇 |
2004年 | 1167篇 |
2003年 | 1129篇 |
2002年 | 1057篇 |
2001年 | 1340篇 |
2000年 | 979篇 |
1999年 | 622篇 |
1998年 | 492篇 |
1997年 | 474篇 |
1996年 | 482篇 |
1995年 | 561篇 |
1994年 | 558篇 |
1993年 | 469篇 |
1992年 | 487篇 |
1991年 | 471篇 |
1990年 | 514篇 |
1989年 | 487篇 |
1988年 | 428篇 |
1987年 | 384篇 |
1986年 | 353篇 |
1985年 | 361篇 |
1984年 | 413篇 |
1983年 | 368篇 |
1982年 | 426篇 |
1981年 | 375篇 |
1980年 | 319篇 |
1979年 | 357篇 |
1978年 | 305篇 |
1977年 | 254篇 |
1975年 | 246篇 |
1974年 | 264篇 |
1973年 | 263篇 |
1972年 | 260篇 |
1971年 | 228篇 |
排序方式: 共有10000条查询结果,搜索用时 833 毫秒
551.
A. G. W. Hunter M.D. 《黑龙江环境通报》1987,7(6):433-441
Three hundred and fifty-four women who underwent midtrimester genetic amniocentesis were matched for age, parity, indication, and smoking history, with an equivalent number of women who had declined the procedure, for the purpose of comparing the neonatal respiratory status of their offspring. There was no evidence that the infants exposed to genetic amniocentesis were compromised. 相似文献
552.
553.
Lee P. Shulman MD Patricia L. Gordon Donald S. Emerson R. Sidney Wilroy Sherman Elias 《黑龙江环境通报》1993,13(5):403-409
We describe the prenatal diagnosis of isolated bilateral fetal microphthalmia in a woman at increased risk of having a fetus with microphthalmia. Ultrasound examinations at 161 and 19-5 weeks' gestation demonstrated bilateral fetal microphthalmia with no other associated structural defects. The patient elected to terminate her pregnancy at 19.5 weeks. Pathological evaluation of the products of conception obtained by dilation and evacuation confirmed the prenatal diagnosis of isolated bilateral fetal microphthalmia. 相似文献
554.
E.F. Brünig 《Agriculture, ecosystems & environment》1984,11(2):191
555.
Prenatal diagnosis of trisomy 20 mosaicism was made in two pregnancies by chromosome analysis of cultured amniotic fluid cells. In both cases, the pregnancy continued to term and a healthy male infant was delivered. Regular assessments up to the age of 6-5 years revealed normal physical and intellectual development in both children. 相似文献
556.
In the case-control study of 118 women with autosomal trisomy identified at prenatal diagnosis and their 442 karyotypically normal matched controls, we found that there was no overall association between risk of trisomy and the presence of vaginal bleeding during pregnancy. However, a lengthy duration of bleeding appears to predict increased risk of trisorny. 相似文献
557.
558.
We report in detail two series of chorionic villus cultivation for prenatal chromosomal diagnosis. Chorionic villi were sampled from both first- and second-trimester pregnancies. One hundred cultures were treated with trypsin–EDTA for 2 h and collagenase overnight, (method A) and 100 were treated with trypsin–EDTA for 1 h and collagenase for 2 h (method B). Using short-term enzymatic digestion, the cultivation time was reduced from 14 days to 6 days. Sufficient amounts of metaphases of good quality were present in 93 per cent of primary cultures harvested in situ, whereas enough metaphases of sufficiently good quality were in most cases present only after subcultivation of the cultures using method A. The decrease in cultivation time obtained is probably due to a higher yield of viable cells in monocellular suspension, an increased attachment efficiency, and a more rapid attachment of single cells (within 24 h). 相似文献
559.
560.
Masera Omar R. Cerón Alma Delia Ordóñez Antonio 《Mitigation and Adaptation Strategies for Global Change》2001,6(3-4):291-312
We examine carbon (C) reference and mitigation scenarios for the Mexicanforest sector between the year 2000 and 2030. Estimates are presentedseparately for the period 2008–2012.Future C emissions and capture are estimated using a simulation modelthat: a) allocates the country land use/land cover classes among differentfuture uses and categories using demand-based scenarios for forestryproducts; b) estimates the total C densities associated to each land usecategory, and c) determines the net carbon implications of the process ofland use/cover change according to the different scenarios.The options analyzed include both afforestation/reforestation, such ascommercial, bionenergy and restoration plantations, and agroforestrysystems, and forest conservation, through the sustainable management ofnative forests and forest protection.The total mitigation potential, estimated as the difference between the totallong-term carbon stock in the reference and the mitigation scenario reaches300 × 106 Mg C in the year 2012 and increases to 1,382 × 106 Mg C in 2030. The average net sequestration in the 30 year period is 46 × 106 Mg C yr-1, or 12.5 × 106 Mg C yr-1 within the period 2008 to 2012. The costs of selected mitigation options range from 0.7–3.5 Mg C-1 to 35 Mg C-1. Some options are cost effective. 相似文献