全文获取类型
收费全文 | 11180篇 |
免费 | 1111篇 |
国内免费 | 3677篇 |
专业分类
安全科学 | 1620篇 |
废物处理 | 614篇 |
环保管理 | 1174篇 |
综合类 | 7422篇 |
基础理论 | 2630篇 |
环境理论 | 4篇 |
污染及防治 | 1115篇 |
评价与监测 | 811篇 |
社会与环境 | 378篇 |
灾害及防治 | 200篇 |
出版年
2024年 | 64篇 |
2023年 | 250篇 |
2022年 | 393篇 |
2021年 | 473篇 |
2020年 | 451篇 |
2019年 | 429篇 |
2018年 | 407篇 |
2017年 | 484篇 |
2016年 | 608篇 |
2015年 | 670篇 |
2014年 | 722篇 |
2013年 | 1075篇 |
2012年 | 975篇 |
2011年 | 954篇 |
2010年 | 735篇 |
2009年 | 720篇 |
2008年 | 555篇 |
2007年 | 764篇 |
2006年 | 776篇 |
2005年 | 577篇 |
2004年 | 480篇 |
2003年 | 496篇 |
2002年 | 417篇 |
2001年 | 379篇 |
2000年 | 364篇 |
1999年 | 260篇 |
1998年 | 209篇 |
1997年 | 203篇 |
1996年 | 193篇 |
1995年 | 180篇 |
1994年 | 143篇 |
1993年 | 107篇 |
1992年 | 84篇 |
1991年 | 83篇 |
1990年 | 66篇 |
1989年 | 50篇 |
1988年 | 41篇 |
1987年 | 36篇 |
1986年 | 17篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 14篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Ellen Sidransky Susan H. Black Dawn M. Soenksen Shirley L. Jones Andrew D. Dorfmann Joseph D. Schulman MD 《黑龙江环境通报》1990,10(9):583-586
Chorionic villus sampling (CVS) with either transcervical catheters or transabdominal needles is a widely-accepted method for prenatal diagnosis. However, there exists a small subset of patients in whom sampling is difficult or impossible with either route because of individual anatomic variations. A new method of chorionic villus biopsy has been developed to circumvent these problems, utilizing transvaginal chorionic needle aspiration guided by an intravaginal ultrasound probe. This technique was performed successfully in 15 patients in whom villi could not be obtained by either of the conventional methods. This method now makes CVS possible in essentially all women regardless of their uterine anatomy or placental placement; it may also prove useful for very early chorionic sampling. 相似文献
92.
This paper reports results of an exploratory study of prenatal diagnosis patients who experienced voluntary terminations of pregnancy following the detection of an abnormality or spontaneous miscarriages. The 121 participants were part of the national collaborative Chorionic Villus Sampling and Amniocentesis Study. They completed semi-structured telephone interviews and mailed questionnaires at 1 month and 6 months after the pregnancy losses. Scores on the Profile of Mood States showed that mood levels improved significantly over time. However, there were some declines in loss-related support from partners and others. The persisting distress and difficulties of a minority highlight the variability in women's responses to pregnancy losses. Women who lost pregnancies later in gestation, showed the greatest mood disturbances at initial assessments, used professional mental health assistance after the loss, or reported less satisfactory loss-related support from significant others showed the greatest levels of mood disturbance at the six-month assessment. Follow-up contacts with patients who lose pregnancies should be used to inform women about the variation in possible grief reactions, to assess the extent of support the women are receiving from their partners and significant others, and to provide additional follow-up or referral of those experiencing the greatest distress. 相似文献
93.
Dr. C. Dawn DeLozier-Blanchet Eric Engel Philippe Extermann Béatrice Pastori 《黑龙江环境通报》1988,8(4):281-286
Cytogenetic study of chorionic villi sampled because of advanced maternal age revealed, after overnight culture, an apparently non-mosaic trisomy 7. Amniocentesis showed exclusively normal mitoses, and the pregnancy continued normally. One hundred mitoses from cord blood of the normal newborn revealed a non-mosaic 46,XX complement. No cells with a proven trisomy 7 were found in cultures from either of two biopsies of the morphologically normal placenta, but the peripheral biopsy showed in multiple cultures an abnormal clone: 47,XX, + 20,-2,-21, + t(2;21)(p13;q22). To our knowledge, this is the first case of non-mosaic trisomy 7 detected on CVS which has had follow-up studies of amniotic fluid, cord blood, and term placenta. 相似文献
94.
M. L. Smith O. L. Pellett M. M. J. Cass N. G. Kennaway N. R. M. Buist J. Buckmaster M. Golbus G. S. Spear J. A. Schneider 《黑龙江环境通报》1987,7(1):23-26
The prenatal diagnosis of cystinosis is currently based on the increased amount of free-cystine present in amniotic fluid cells. Amniocyte cultures must be grown for at least 2 weeks to obtain sufficient cells for such measurements. Thus, the diagnosis cannot be made until close to 20 weeks gestational age by this method. We report a case in which chorionic villi were used for direct cystine measurement resulting in the in utero diagnosis of cystinosis at 9 weeks gestational age. The diagnosis was confirmed by the study of cultured chorionic villus cells, and of the 10-week abortus. 相似文献
95.
The prenatal diagnosis of The Turner Syndrome is described at a menstrual age of 12 weeks. Detection of cystic hygroma was followed by vaginal chorionic villous sampling (CVS) which revealed a 45,X karyotype. Early documentation of fetal karyotype in the presence of a cystic hygroma is essential for accurate diagnosis and genetic counselling. 相似文献
96.
综述了土壤及地下水系统中反硝化作用的研究进展,详细地介绍了反硝化作用的原理和机制,用以防治地表水和地下水的污染。 相似文献
97.
Upper limb reduction was diagnosed by ultrasound scan at 17 weeks after chorion villus sampling at 9 weeks' gestation. Pregnancy was terminated and necropsy confirmed limb reduction in an otherwise normal fetus. The relationship of limb reduction to amniotic band syndrome is discussed. 相似文献
98.
电化学法烟气脱硫制取浓硫酸 总被引:1,自引:0,他引:1
利用电化学脱硫生产硫酸是一种自然资源再利用的新型大气环保技术 ,它通过电解I- /I2 体系生成I2 来吸收氧化烟气中的SO2 ,其脱硫率可达 95%~ 99% ,并生成 85%以上的高浓度硫酸和纯氢。以期获得废渣废液的零排放。 相似文献
99.
Effects of atmospheric mercury pollution on terrestrial ecosystem in Chongqing, China 总被引:1,自引:0,他引:1
1 IntroductionMercury(Hg)asaglobalpollutanthascausedconcernworldwidesincetheendof 1980s.Itisemittedtotheatmospherefrombothanthropogenicandnaturalsources.Importantsourceoftheformeristhedischargefrom productionanduseofHgaswellasthecombustionoffossilfuels(Nri… 相似文献
100.
Ensegam A.M. Zohny 《环境科学学报(英文版)》2002,14(1):34-38
IntroductionInnatureCooccursintwooxidationstates ,Co2 + andCo3+ ,andformationofthecomplexanionCo(OH) - 3 isalsopossible .DuringweatheringCoisrelativelymobileinoxidizingacidenvironment,butduetoahighsorptionbyFeandMnoxides,aswellasbyclayminerals,thismetaldoesnotm… 相似文献