全文获取类型
收费全文 | 23185篇 |
免费 | 215篇 |
国内免费 | 193篇 |
专业分类
安全科学 | 625篇 |
废物处理 | 818篇 |
环保管理 | 3264篇 |
综合类 | 5275篇 |
基础理论 | 5461篇 |
环境理论 | 10篇 |
污染及防治 | 5890篇 |
评价与监测 | 1244篇 |
社会与环境 | 887篇 |
灾害及防治 | 119篇 |
出版年
2021年 | 159篇 |
2018年 | 270篇 |
2017年 | 253篇 |
2016年 | 412篇 |
2015年 | 324篇 |
2014年 | 442篇 |
2013年 | 1711篇 |
2012年 | 601篇 |
2011年 | 834篇 |
2010年 | 635篇 |
2009年 | 785篇 |
2008年 | 843篇 |
2007年 | 937篇 |
2006年 | 831篇 |
2005年 | 650篇 |
2004年 | 694篇 |
2003年 | 713篇 |
2002年 | 633篇 |
2001年 | 841篇 |
2000年 | 603篇 |
1999年 | 406篇 |
1998年 | 257篇 |
1997年 | 257篇 |
1996年 | 279篇 |
1995年 | 320篇 |
1994年 | 322篇 |
1993年 | 289篇 |
1992年 | 297篇 |
1991年 | 310篇 |
1990年 | 303篇 |
1989年 | 303篇 |
1988年 | 282篇 |
1987年 | 259篇 |
1986年 | 221篇 |
1985年 | 243篇 |
1984年 | 257篇 |
1983年 | 266篇 |
1982年 | 265篇 |
1981年 | 239篇 |
1980年 | 219篇 |
1979年 | 229篇 |
1978年 | 209篇 |
1977年 | 186篇 |
1976年 | 188篇 |
1975年 | 176篇 |
1974年 | 215篇 |
1973年 | 169篇 |
1972年 | 175篇 |
1970年 | 152篇 |
1967年 | 169篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
581.
Consanguineous partners had a boy with campomelic dysplasia who died of increasing respiratory distress soon after birth. The next pregnancy was monitored frequently by ultrasonography and a healthy male infant was born at term. During a further pregnancy, ultrasonography suggested campomelic dysplasia in the 16th week of gestation. This was confirmed in the 18th week. The pregnancy was terminated and the fetus showed the typical radiological, anatomical and histological findings. 相似文献
582.
C. Marchese M.D. E. Savin E. Dragone F. Carozzi M. De Marchi M. Campogrande G. C. Dolfin G. Pagliano E. Viora A. Carbonara 《黑龙江环境通报》1985,5(3):221-227
Six cases of cystic hygromas detected during second trimester ultrasound examination are reported: 4 fetuses (67 per cent) had a 45, X karyotype, 1 fetus had trisomy 18, 1 fetus had a normal karyotype (46,XX) and at autopsy multiple anomalies were observed. In the latter case the family history suggested an autosomal recessive pattern of inheritance. In order to reach a definite diagnosis and give proper genetic counselling when a fetus is found to have cystic hygroma, a fetal karyotype as well as a family and reproductive history should be obtained. 相似文献
583.
Routine ultrasound examination at 30 weeks gestation revealed an intrapulmonary cystic mass in an otherwise normal fetus. Following delivery at term, the diagnosis of congenital cystic adenomatoid malformation of the right lung was confirmed, and an elective right middle lobectomy successfully performed at nine days of age. 相似文献
584.
In 40 pregnancies at risk for the Hurler syndrome 13 affected fetuses were detected by the demonstration of an α-L -iduronidase deficiency and an increased level of 35S-sulphate incorporation. The diagnoses were confirmed by the analysis of fetal tissues and/or cultured fetal skin fibroblasts. Microassays for α-L -iduronidase, using phenyl α-L -iduronide and more recently 4–methyl-umbelliferyl α-L -iduronide, enabled a reliable diagnosis to be made within 15 to 18 days after amniocentesis. 35S-sulphate incorporation has been a valuable adjunct in cases with a low (heterozygote) enzyme activity. 相似文献
585.
586.
Ossie Geifman-Holtzman Eliezer J. Holtzman Theresa J. Vadnais Vincent E. Phillips Eleanor L. Capeless Diana W. Bianchi MD 《黑龙江环境通报》1995,15(3):261-268
The objective of this study was to detect fetal HLA-DQα gene sequences in maternal blood. HLA-DQα genotypes of 70 pregnant women and their partners were determined for type A1. We specifically sought couples where the father, but not the mother, had genotype A1. In 12 women, maternal blood samples were flow-sorted. Candidate fetal cells were isolated and amplified by using PCR primers specific for a paternal HLA-DQα A1 allele. Fetal HLA-DQα A1 genotype was predicted from sorted cells; amniocytes or cheek swabs were used for confirmation. Six of twelve sorted samples had amplification products indicating the presence of the HLA-DQα A1 allele; 6/12 did not. Prediction of the fetal genotype was 100 per cent correct, as determined by subsequent amplification of amniocytes or cheek swabs. We conclude that paternally inherited uniquely fetal HLA-DQα gene sequences can be identified in maternal blood. This system permits the identification of fetal cells independent of fetal gender, and has the potential for non-invasive prenatal diagnosis of paternally inherited conditions. 相似文献
587.
This study provides data on the incidence of fetal trisomies 21, 18, and 13 at 9–14 weeks' gestation in women aged 35–45 years and estimates of maternal age-specific risks in women aged 20–45 years. Our data from 5814 singleton pregnancies undergoing first-trimester karyotyping for the sole indication of maternal age ⩾ 35 years were combined with those from two previous reports and the incidence of the trisomies was calculated from a total of 15 793 pregnancies. Comparison of incidences at 9–14 weeks' gestation with published data at 15–20 weeks' gestation and in livebirths demonstrated that at birth the maternal age-specific incidence of trisomy 21 is 33 per cent lower than at 15–20 weeks' gestation and 54 per cent lower than at 9–14 weeks' gestation. Furthermore, the relative frequency of trisomies 18 and 13 decreases from 30 per cent at 9–14 weeks to 22 per cent at 15–20 weeks and 14 per cent at birth. 相似文献
588.
Ultrasound examination at 12 weeks' gestation revealed severe generalised subcutaneous oedema in a pregnancy at risk for achondrogenesis type II. Transvaginal scanning confirmed the oedema and suggested abnormal limb development. The prenatal diagnosis was confirmed by X-ray examination after transvaginal termination. 相似文献
589.
The value of maternal serum pregnancy-associated plasma protein (PAPP)-A in screening for Down syndrome in early pregnancy was assessed using stored samples. Seventeen cases of Down syndrome and 66 unaffected control pregnancies were studied. The median PAPP-A level in the cases was 0.42 multiples of the expected value in controls (p <0.0001). Eleven cases (65 per cent) had levels less than half the expected value compared with only six controls (9 per cent). A commercial assay kit is now needed so that prospective screening with this marker can begin. 相似文献
590.
The discussion on the possible increase of solar UV on earth due to the destruction of the stratospheric ozone has led to a renewed interest in the action of ultraviolet radiation on biological systems. The paper deals with changes at the cellular level stressing particularly molecular alterations in deoxyribonucleic acid, the carrier of genetic information. The most important repair processes by which lesions are removed or bypassed are described. It is also discussed whether the effectivity of a complex spectrum can be predicted on the basis of measurements with monochromatic radiation. Furthermore, possible consequences on human health are outlined which may be derived from cellular studies. 相似文献