全文获取类型
收费全文 | 1771篇 |
免费 | 6篇 |
专业分类
安全科学 | 461篇 |
废物处理 | 2篇 |
环保管理 | 106篇 |
综合类 | 1039篇 |
基础理论 | 102篇 |
污染及防治 | 52篇 |
评价与监测 | 8篇 |
社会与环境 | 4篇 |
灾害及防治 | 3篇 |
出版年
2015年 | 8篇 |
2013年 | 52篇 |
2011年 | 8篇 |
2010年 | 13篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 13篇 |
2005年 | 10篇 |
2004年 | 161篇 |
2003年 | 162篇 |
2002年 | 73篇 |
2001年 | 40篇 |
1998年 | 47篇 |
1997年 | 15篇 |
1995年 | 58篇 |
1994年 | 56篇 |
1993年 | 41篇 |
1992年 | 34篇 |
1991年 | 27篇 |
1990年 | 34篇 |
1989年 | 26篇 |
1988年 | 36篇 |
1987年 | 31篇 |
1986年 | 27篇 |
1985年 | 17篇 |
1984年 | 13篇 |
1983年 | 16篇 |
1982年 | 12篇 |
1975年 | 12篇 |
1973年 | 10篇 |
1963年 | 9篇 |
1961年 | 9篇 |
1957年 | 9篇 |
1956年 | 8篇 |
1954年 | 8篇 |
1940年 | 10篇 |
1939年 | 10篇 |
1931年 | 12篇 |
1930年 | 10篇 |
1925年 | 7篇 |
1923年 | 9篇 |
1921年 | 9篇 |
1920年 | 7篇 |
1919年 | 50篇 |
1918年 | 45篇 |
1917年 | 36篇 |
1916年 | 55篇 |
1915年 | 38篇 |
1914年 | 74篇 |
1913年 | 106篇 |
排序方式: 共有1777条查询结果,搜索用时 578 毫秒
801.
Dr. I. V. Tsvetkova T. V. Zolotukhina V. A. Bakharev E. L. Rosenfeld I. S. Rosovsky 《黑龙江环境通报》1983,3(3):233-236
Chorion biopsy specimens were used for prenatal assay of arylsulphatase A activity in a pregnant woman whose two children had died from metachromatic leukodystrophy (MLD). As in two subsequent pregnancies chorion arylsulphatase A was in the control range, it was concluded that both fetuses were healthy. Absence of MLD in the fetus from the first pregnancy was confirmed after assay of arylsuphatase A activity in fetal organs. The second pregnancy resulted in delivery of a healthy child. 相似文献
802.
We describe further development of the fumarylacetoacetase (FAA) assay for the prenatal diagnosis of tyrosinaemia type 1 using chorionic villus sampling (CVS). We have established a reference range for FAA activity in cultured villus cells and have confirmed previously reported data on the FAA activity in uncultured chorionic villus cells. This should allow confirmation of results using CVS, without the need for further invasive procedures. We report the FAA enzyme stability at −70°C, +4°C, and at room temperature, and we have shown no obvious difference in enzyme activity with gestational age. We have analysed cultured and non-cultured CVS activity of FAA in two pregnancies at risk of tyrosinaemia type 1. In both, the fetus was designated unaffected, and these results were confirmed postnatally. 相似文献
803.
We report the use of DNA probes to determine carrier status in three young women from a large kindred with Norrie disease. One of the women requested prenatal diagnosis during pregnancy. In this pedigree, Norrie disease was not characterized by a deletion at DXS7. 相似文献
804.
Hypospadias is one of the most prominent and characteristic midline defects in male infants with the Wolf-Hirschhorn (4p —) syndrome. In this report we present a case in which hypospadias was identified prenatally at 29 weeks' gestation in association with intrauterine growth retardation. Cytogenetic evaluation after birth confirmed a 46, XY, del(4)(p14) karyotype. The prenatal identification of hypospadias in fetuses with intrauterine growth retardation and normal amniotic fluid should suggest a diagnosis of Wolf-Hirschhorn syndrome. 相似文献
805.
The prenatal sonographic findings in a case of Walker-Warburg syndrome are described. The patient was not at risk for this condition. Ultrasound examination at 34 weeks' gestation revealed hydrocephaly, Dandy-Walker anomaly, and striking ocular abnormalities. From a review of the literature it appears that while intracranial abnormalities can lead to the diagnosis in cases at risk for this syndrome, ocular abnormalities are rather characteristic for this syndrome and they should be searched for in every case of hydrocephaly or encephalocele. 相似文献
806.
The prenatal diagnosis of thrombocytopenia absent radius (TAR) syndrome, utilizing ultrasound and cordocentesis, is described. To our knowledge, this represents the first prenatal diagnosis of this condition in an index case. The diagnostic evaluation of a fetus with upper extremity limb reduction defects is discussed. 相似文献
807.
We report the prenatal diagnosis of Wolf-Hirschhorn syndrome (4p –) in a 24-week-old fetus. Echographic features included cystic hygroma, a complex heart defect with right ventricular hypoplasia, and a large placental chorioangioma. We suggest that chorioangioma may be associated with chromosomal imbalance and that systematic careful morphologic examination of the fetus and karyotyping of any pregnancy in which large chorioangioma is detected is advisable. Jugular lymphatic obstruction sequence has not been reported so far in association with 4p– syndrome. 相似文献
808.
In accordance with observations by other groups direct CVS preparations reveal only a few mitoses, whereas semi-direct cultures (overnight incubation) give good results. By monitoring the BrdU uptake with an immunological method, a delay in the proliferation activity in native villi could be observed up to 7 h after biopsy. 相似文献
809.
L. Shivashankar E. Whitney G. Colmorgen T. Young G. Munshi D. Wilmoth K. Byrne G. Reeves Dr. D. S. Borgaonkar S. R. Picciano P. A. Marttn-Deleon 《黑龙江环境通报》1988,8(2):85-91
A case of tetrasomy i(12p) detected prenatally is reported. The patient, a black, 33-year-old G3P2002 at 24 weeks' gestation with an unremarkable family history presented herself for prenatal care. Ultrasound examination showed a fetus with diminished femoral and humeral lengths, and hydramnios. A level II scan confirmed the presence of an omphalocele. Amniocentesis at 31 weeks showed 47,XY, + i(12p) karyotype. An infant with multiple congenital anomalies was delivered at 34 weeks. The infant died after 5 h. Genetic and ultrasonographic examinations in the third trimester were helpful in the investigation of this fetus with multiple congenital anomalies. The careful, complete team counselling afforded by this approach enabled the mother and family to be well adjusted to the strong possibility (and subsequent reality) of an abnormal infant. 相似文献
810.
Dr M. Bergere J. Selva M. Baud M. Volante B. Martin J. N. Hugues F. Olivennes R. Frydman M. Auroux 《黑龙江环境通报》1995,15(9):835-841
We performed fluorescence in situ hybridization (FISH) with a chromosome 18-specific probe on human abnormal cleaved embryos, fertilized either by two spermatozoa and exhibiting three pronuclei (3 PN) or normally fertilized and exhibiting two pronuclei (2 PN) with subsequent severe fragmentation and/or blocking. The aim of the study was to evaluate the incidence of chromosome 18 anomalies among these embryos, in order to evaluate the FISH efficiency on such material and to obtain more precise and complete data than those obtained with classical cytogenetic analysis. For the 3 PN cleaved embryos, FISH confirmed the frequent regulation towards diploidy (25 per cent) and the high frequency of mosaics (53 per cent). For the 2 PN blocked or damaged embryos, FISH permitted chromosome evaluation, which was otherwise impossible with classical cytogenetic techniques: we also found a high mosaic frequency (45 per cent) with these embryos. If this frequency were the same for normally developing embryos, it would be a major obstacle to the reliability of either chromosomal or genetic preimplantation diagnosis. 相似文献