全文获取类型
收费全文 | 41054篇 |
免费 | 426篇 |
国内免费 | 309篇 |
专业分类
安全科学 | 1089篇 |
废物处理 | 1568篇 |
环保管理 | 5363篇 |
综合类 | 7499篇 |
基础理论 | 11085篇 |
环境理论 | 27篇 |
污染及防治 | 10413篇 |
评价与监测 | 2487篇 |
社会与环境 | 2027篇 |
灾害及防治 | 231篇 |
出版年
2022年 | 272篇 |
2021年 | 278篇 |
2019年 | 293篇 |
2018年 | 549篇 |
2017年 | 525篇 |
2016年 | 786篇 |
2015年 | 664篇 |
2014年 | 932篇 |
2013年 | 2946篇 |
2012年 | 1138篇 |
2011年 | 1675篇 |
2010年 | 1363篇 |
2009年 | 1430篇 |
2008年 | 1690篇 |
2007年 | 1793篇 |
2006年 | 1612篇 |
2005年 | 1356篇 |
2004年 | 1369篇 |
2003年 | 1305篇 |
2002年 | 1266篇 |
2001年 | 1634篇 |
2000年 | 1116篇 |
1999年 | 750篇 |
1998年 | 556篇 |
1997年 | 577篇 |
1996年 | 593篇 |
1995年 | 655篇 |
1994年 | 602篇 |
1993年 | 548篇 |
1992年 | 537篇 |
1991年 | 513篇 |
1990年 | 515篇 |
1989年 | 517篇 |
1988年 | 474篇 |
1987年 | 408篇 |
1986年 | 378篇 |
1985年 | 408篇 |
1984年 | 420篇 |
1983年 | 433篇 |
1982年 | 449篇 |
1981年 | 385篇 |
1980年 | 340篇 |
1979年 | 355篇 |
1978年 | 324篇 |
1977年 | 275篇 |
1976年 | 277篇 |
1975年 | 274篇 |
1974年 | 259篇 |
1973年 | 243篇 |
1972年 | 270篇 |
排序方式: 共有10000条查询结果,搜索用时 33 毫秒
891.
Dr J. L. Carrasco Juan A. Otero Gómez M. C. Vilar Mesa J. L. García Miranda J. M. Troyano Luque O. Morales Ruiz J. Parache Hernández 《黑龙江环境通报》1989,9(6):443-445
A dicentric X chromosome was found in a female fetus during cytogenetic studies performed on amniotic cells. Blood samples from the parents showed normal karyotypes and the pregnancy was terminated. The mechanism for the formation of this ‘de novo’ rearrangement is discussed. 相似文献
892.
Iniencephaly is an uncommon, but not rare, lesion involving a fusion between the posterior occipital bone and the cervical spine. Many cases are associated with other cranio-cervical abnormalities and anencephaly, and most are associated with other structural abnormalities. The prognosis is thought to be dismal. We describe a male infant, one of twins, who was diagnosed prenatally as having iniencephaly. The child was born without complication and has grown and thrived. This is the fourth patient with long-term survival with iniencephaly. We recommend that non-directive counselling be applied when presenting the findings of iniencephaly to parents. 相似文献
893.
Marcy C. Speer Margaret A. Pericak-Vance Larry H. Yamaoka James Koh Wu-Yen Hung Peter C. Gaskell Jr. Jeffery M. Vance Richard J. Bartlett Allen D. Roses 《黑龙江环境通报》1988,8(6):427-437
Accurate carrier testing and prenatal diagnosis in Duchenne muscular dystrophy (DMD) families is facilitated when an Xp21 deletion is found to be segregating within a family. We discuss the results of the DNA testing in two families, one in which DNA from affected males was available for study and the other in which no DNA from an affected male was available. Factors complicating the counselling of DMD deletion families are outlined. 相似文献
894.
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
895.
The outcome of the pregnancy following (a) a mid-trimester termination of pregnancy (TOP) for fetal neural tube defect (NTD) (77 women=group 1); (b) mid-trimester TOP for fetal Down's syndrome (13 women=group 2); (c) delivery of a baby with NTD (119 women=group 3) was studied. The prenatal fetal loss was relatively high in all groups. In group 1 it was similar to that found in other studies after first trimester TOP, in group 2 it was associated with advanced maternal age and the unexpected finding in group 3 was not attributable to advanced maternal age. It is suggested that a previous NTD per se might increase the risk of fetal loss in the next pregnancy. A previous mid-trimester TOP for NTD was not associated with an increase in premature labour, small for dates babies or congenital abnormality in the next pregnancy, but there was a slight increase in the number of babies weighing less than 2500 g. 相似文献
896.
J. G. Hooker M. Lucas B. A. Richards I. M. Shirley B. D. Thompson R. H. T. Ward 《黑龙江环境通报》1984,4(1):29-33
Estimation of maternal serum alpha-fetoprotein (AFP) was used as a screening method for the detection of neural tube defects (NTDs) in 6344 women over three years. Of 88 (1.4 per cent) who had one or more serum AFP levels equal to, or greater than, 2.5 multiples of the median (MoM) for the relevant gestational age, 43 (0.68 per cent) underwent amniocentesis. There were eight NTDs. Four of these were screened by serum AFP, and all cases of spina bifida had serum AFP levels greater than 3.0 MoM, including one small open defect which was not seen on ultrasound. The other four cases of NTD, which were not screened, were identified by ultrasound. Of 64 singleton pregnancies 32 (50 per cent) had serum AFP levels between 2.5 and 3.0 MoM, and low birthweight (⪕2500 g) occurred in 29 per cent. Because of improvements in ultrasound techniques and the apparent falling incidence of NTD, the role of serum AFP as the primary screening procedure should be regularly reviewed. Effective screening is dependent on mothers booking early. 相似文献
897.
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
898.
True microcephaly can be diagnosed at an early stage of gestation by serial measurements of fetal head growth as demonstrated by this case report in which the diagnosis of genetic microcephaly was made but termination refused. True microcephaly was evident at birth. 相似文献
899.
900.