全文获取类型
收费全文 | 806篇 |
免费 | 51篇 |
国内免费 | 238篇 |
专业分类
安全科学 | 110篇 |
废物处理 | 53篇 |
环保管理 | 45篇 |
综合类 | 495篇 |
基础理论 | 219篇 |
污染及防治 | 149篇 |
评价与监测 | 13篇 |
社会与环境 | 8篇 |
灾害及防治 | 3篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 15篇 |
2021年 | 12篇 |
2020年 | 27篇 |
2019年 | 24篇 |
2018年 | 28篇 |
2017年 | 32篇 |
2016年 | 35篇 |
2015年 | 36篇 |
2014年 | 34篇 |
2013年 | 92篇 |
2012年 | 69篇 |
2011年 | 76篇 |
2010年 | 34篇 |
2009年 | 40篇 |
2008年 | 42篇 |
2007年 | 54篇 |
2006年 | 43篇 |
2005年 | 49篇 |
2004年 | 33篇 |
2003年 | 35篇 |
2002年 | 31篇 |
2001年 | 27篇 |
2000年 | 30篇 |
1999年 | 26篇 |
1998年 | 23篇 |
1997年 | 16篇 |
1996年 | 17篇 |
1995年 | 30篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 3篇 |
排序方式: 共有1095条查询结果,搜索用时 15 毫秒
221.
M. R. Thomas B. Tutschek A. Frost C. H. Rodeck N. Yazdani I. Craft R. Williamson 《黑龙江环境通报》1995,15(7):641-646
A single copy Y-chromosome DNA sequence was amplified using the polymerase chain reaction (PCR) from the peripheral blood of 30 women who had achieved a pregnancy through an in vitro fertilization (IVF) programme. The time of conception was known precisely and was confirmed by serial ultrasound scans. Conceptions were dated as the number of weeks after fertilization plus 2, to give a time equivalent to the obstetric menstrual dating of the pregnancy (LMP). Y-chromosome-specific DNA was detected in all pregnancies with a male fetus (18/30). The earliest detection was at 4 weeks and 5 days, and the latest at 7 weeks and 1 day. Y-chromosome-specific sequences were no longer detected in any of the male pregnancies 8 weeks after delivery. No Y-chromosome sequences were detected in any of the pregnancies where only female babies were delivered. This demonstrates that fetal DNA appears in the maternal circulation early in the first trimester, that it can be identified in all pregnancies tested by 7 weeks, that it continues to be present throughout pregnancy, and that it has been cleared from the maternal circulation 2 months after parturition. Early non-invasive prenatal diagnosis for aneuploidies and inherited disorders will be possible in all pregnancies if fetal cells can be isolated free from maternal contamination (or identified accurately in the presence of maternal cells) without problems of contamination from previous pregnancies. 相似文献
222.
F. Daffos F. Forestier J. Mac Aleese C. Aufrant L. Mandelbrot E. A. Cabanis M. T. Iba-Zizen J. M. Alfonso J. Tamraz 《黑龙江环境通报》1988,8(4):311-314
Fetal magnetic resonance (MR) imaging was performed at 33 weeks of gestation for investigation of a posterior fossa abnormality found at ultrasound screening. Fetal movements were abolished by vecuronium injected under ultrasound guidance into the umbilical vein. MR images showed atrophy of the left cerebellar lobe with cisternal dilatation. These were confirmed postnatally by CT scan. 相似文献
223.
A longitudinal study was carried out on 30 healthy fetuses in order to assess the modifications of fetal blood flow throughout pregnancy. The pulsatility index was evaluated at two-week intervals by means of pulsed Doppler equipment. In the umbilical artery measurements were performed from 20 weeks onwards, whereas in the descending aorta and internal carotid artery analysis started from 26 weeks onwards. A decrease of the pulsatility index in umbilical artery and in the ratio between the pulsatility indexes in umbilical artery and internal carotid artery was found over the second half of pregnancy. 相似文献
224.
Investigation of protein-styrene oxide adducts as a molecularbiomarker of human exposed to styrene 总被引:2,自引:0,他引:2
IntroductionBiomarker ,definedascellular,biochemicalormolecularalterationsthataremeasurableinbiologicalmedia ,suchashumantissues ,cells,orfluids ,havebeenusedbygenerationsofepidemiologistsintheirresearch .Molecularbiologyandlaboratorytechnologyhaveshownane… 相似文献
225.
粉状活性炭应用于气浮工艺中能发挥吸附和提供絮聚中心的协同作用 ,提高工艺效率。该工艺对滇池水的色度、COD、BOD及藻类的去除率分别达到 72 %、 57 2 %、 2 4 %和 97 6%。 相似文献
226.
Flow cytometry was used to enumerate the lymphocyte subpopulations in fetal blood obtained by cordocentesis from eight trisomy 18 fetuses at 20–36 weeks' gestation. Compared with values in chromosomally normal fetuses, in trisomy 18 the mean T- and natural killer (NK) cell counts were significantly lower (t= − 7·63, P<0·001 and t= − 3·58, P<0·01, respectively); the mean B-cell count was not significantly different (t= − 1·32). These findings demonstrate that in trisomy 18 there is abnormal intrauterine development of the immune system. 相似文献
227.
Ph. Labrune MD J. C. Pons M. Khalil V. Mirlesse M. C. Imbert M. Odièvre F. Daffos G. Tchernia R. Frydman 《黑龙江环境通报》1993,13(6):463-466
Three fetuses with TAR (thrombocytopenia with absent radii) or TAR variant syndrome were found to be thrombocytopenic during the third trimester of the pregnancy. These findings indicate that fetal blood sampling, besides ultrasonography, skeletal radiographs, or even fetoscopy, may indeed contribute to the prenatal diagnosis of TAR syndrome, and thus may help in differentiating TAR syndrome from other syndromes with malformations of the upper limbs. 相似文献
228.
229.
Dr Helen M. Kingston Consultant Clinical Geneticist Umberto Nicolini John Haslam Tony Andrews 《黑龙江环境通报》1993,13(7):637-642
46,XY/47,XY, + 17p + mosaicism was found in two primary amniotic fluid cultures (AFCs). Fetal blood karyotype was normal, but ultrasonography revealed Dandy-Walker malformation and bilateral choroid plexus cysts. Following termination of pregnancy, fetal examination revealed post-axial polydactyly and neuroblastoma-in-situ affecting both adrenals in addition to the cerebellar abnormalities. Mosaicism for the aberrant cell line was confirmed in all fetal tissues sampled and in the placenta. 相似文献
230.
Metachromatic leucodystrophy was excluded in a fetus at risk, by assay of fetal blood collected at fetoscopy. Isolated fetal leucocytes were shown to have activities of arylsulphatase A and cerebroside sulphatase in the heterozygous range. The prediction was confirmed in the newborn. 相似文献