全文获取类型
收费全文 | 49414篇 |
免费 | 437篇 |
国内免费 | 341篇 |
专业分类
安全科学 | 1131篇 |
废物处理 | 2244篇 |
环保管理 | 6431篇 |
综合类 | 7430篇 |
基础理论 | 14179篇 |
环境理论 | 24篇 |
污染及防治 | 12248篇 |
评价与监测 | 3438篇 |
社会与环境 | 2791篇 |
灾害及防治 | 276篇 |
出版年
2022年 | 296篇 |
2021年 | 282篇 |
2020年 | 240篇 |
2019年 | 311篇 |
2018年 | 1876篇 |
2017年 | 1787篇 |
2016年 | 1878篇 |
2015年 | 817篇 |
2014年 | 1038篇 |
2013年 | 3098篇 |
2012年 | 1629篇 |
2011年 | 2914篇 |
2010年 | 2086篇 |
2009年 | 1995篇 |
2008年 | 2478篇 |
2007年 | 2899篇 |
2006年 | 1649篇 |
2005年 | 1390篇 |
2004年 | 1402篇 |
2003年 | 1356篇 |
2002年 | 1363篇 |
2001年 | 1673篇 |
2000年 | 1189篇 |
1999年 | 731篇 |
1998年 | 554篇 |
1997年 | 570篇 |
1996年 | 583篇 |
1995年 | 643篇 |
1994年 | 586篇 |
1993年 | 512篇 |
1992年 | 543篇 |
1991年 | 499篇 |
1990年 | 507篇 |
1989年 | 539篇 |
1988年 | 445篇 |
1987年 | 405篇 |
1986年 | 377篇 |
1985年 | 403篇 |
1984年 | 413篇 |
1983年 | 427篇 |
1982年 | 415篇 |
1981年 | 351篇 |
1980年 | 324篇 |
1979年 | 354篇 |
1978年 | 302篇 |
1977年 | 267篇 |
1976年 | 247篇 |
1975年 | 245篇 |
1973年 | 248篇 |
1972年 | 264篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
S. Kojima S. Ohta T. Yamamoto T. Miura Y. Fujiwara K. Fujikura J. Hashimoto 《Marine Biology》2002,141(1):57-64
The nucleotide sequence of part (624 bp) of a mitochondrial gene for cytochrome oxidase I was determined for 46 escarpiid vestimentiferans collected from seven sites in the western Pacific and 49 individual specimens of Arcovestia ivanovi from two sites in the Manus Basin. Phylogenetic analysis, based on the newly obtained and previously reported sequences, indicated that escarpiids in the western Pacific can be divided into two tentative species, as we proposed in a previous report. While members of the first tentative species have been collected exclusively from a seep area at a depth of 300 m off the coast of central Japan, the members of the second species inhabit some sites at depths greater than 1,100 m, namely, seep areas in Japanese and Papua-New Guinean waters as well as hydrothermal vent fields in the Okinawa Trough and the Manus Basin. We detected no genetic structure among populations of the second tentative species. The first tentative species was more closely related to a species in the eastern Pacific, Escarpia spicata, and to a species in the Gulf of Mexico, Escarpia laminata, than to the second tentative species in the western Pacific. Sequences obtained from all arcovestiids were identical with the exception of those from three individuals, each of which included a single synonymous nucleotide substitution relative to the dominant haplotype, and no genetic differences were detected between specimens from the two sites in the Manus Basin. 相似文献
55.
V. Nataf M. V. Senat M. Albert L. Bidat P. de Mazancourt J. Roume L. Allard D. Le Tessier Y. Ville J. Selva 《黑龙江环境通报》2002,22(8):675-680
Male phenotype associated with a 45,X karyotype is an infrequent finding. We present a case diagnosed prenatally on amniocentesis performed for maternal age. The male phenotype was associated with a translocation of a distal part of Yp including the pseudoautosomal SHOX gene and SRY gene on the short arm of a chromosome 21. By DNA analysis we could show that the X chromosome was of maternal origin and that the breakpoint was in interval 3 of the Y chromosome. Mechanisms and genetic counselling are discussed based on a review of published cases of 45,X and XX males. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
56.
David L. Skidmore Aditya P. Pai Ants Toi Leslie Steele David Chitayat 《黑龙江环境通报》2003,23(12):1009-1013
Two de novo cases with Apert Syndrome detected prenatally are presented herein. In the first, fetal ultrasound findings of syndactyly of the hands, craniosynostosis and proptosis resulted in a prenatal diagnosis in the nineteenth week of gestation. This is the earliest prenatal diagnosis of this syndrome in a not-at-risk case. Following counseling, this pregnancy was terminated and subsequent pathological examination and DNA analysis confirmed the diagnosis of Apert Syndrome and coarctation of the aorta. In the second case, fetal ultrasound at 21 weeks' gestation revealed a hypoplastic left heart and clover-leaf skull. Following counseling, this pregnancy was also terminated. Further examination of the fetus and DNA analysis led to a diagnosis of Apert Syndrome. These cases emphasize the need to complete a thorough fetal ultrasound in cases with potentially lethal cardiac abnormality and the importance of incorporating a fetal pathologist, as well as a medical geneticist, in the investigations performed after delivery or pregnancy termination when a fetal abnormality is detected on ultrasound. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
57.
58.
59.
P Joseph S Viswanatha M K Krishnakumari 《Journal of environmental science and health. Part. B》1992,27(3):269-280
The haematotoxicity of technical hexachlorocyclohexane (HCH) (1000 ppm) was investigated in male albino rats fed with diet free of vitamin A or containing vitamin A at 2000 or 10(5) I.U./kg. Assessment of HCH-induced haematotoxicity at the end of the 7 weeks feeding period was done on the basis of haemoglobin content, total count of red blood cells and white blood cells and the differential counts of the white blood cells as well as by parameters such as packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin content, prothrombin time and clotting time. In the rats fed with vitamin A-free diet containing HCH, significant reductions were noticed in the total white blood cells count, clotting time and prothrombin time indicating severe haematotoxicity. Differential count of the white blood cells of these rats revealed a non-significant reduction in the lymphocyte count. The only indication of haematotoxicity caused by hexachlorocyclohexane in the vitamin A supplemented rats was a slight but statistically significant reduction of the total count of white blood cells. These results demonstrate that the haematotoxicity of hexachlorocyclohexane in the rats is enhanced by vitamin A-deficiency and its supplementation particularly in excess but not at hypervitaminotic level is protective against the toxicity. 相似文献
60.
As part of a programme to characterize floating anthropogenic debris in the aquatic environment, the US Environmental Protection Agency (EPA) conducted 18 field surveys in the harbours of major metropolitan cities of the east, west, and Gulf coasts of the United States and the Mid-Atlantic Bight. the surveys were designed to provide information on the types, relative amounts, and distributions of aquatic debris in different geographic regions of the United States. Neuston nets (0.33 mm mesh) were used to collect surface debris during outgoing tides on two or three consecutive days in selected areas of each city. After each net tow, the debris, which ranged in size from small resin pellets to large plastic sheeting pieces, was identified, categorized, and counted. the data are being used to qualitatively characterize aquatic debris in coastal metropolitan areas, to examine potential regional variations, and to tentatively identify potential sources. 相似文献