全文获取类型
收费全文 | 61427篇 |
免费 | 810篇 |
国内免费 | 3903篇 |
专业分类
安全科学 | 1973篇 |
废物处理 | 3100篇 |
环保管理 | 7573篇 |
综合类 | 12412篇 |
基础理论 | 16276篇 |
环境理论 | 27篇 |
污染及防治 | 16434篇 |
评价与监测 | 4212篇 |
社会与环境 | 3438篇 |
灾害及防治 | 695篇 |
出版年
2023年 | 326篇 |
2022年 | 810篇 |
2021年 | 756篇 |
2020年 | 540篇 |
2019年 | 599篇 |
2018年 | 2223篇 |
2017年 | 2199篇 |
2016年 | 2336篇 |
2015年 | 1401篇 |
2014年 | 1905篇 |
2013年 | 4506篇 |
2012年 | 2588篇 |
2011年 | 3845篇 |
2010年 | 2841篇 |
2009年 | 2711篇 |
2008年 | 3324篇 |
2007年 | 3556篇 |
2006年 | 2282篇 |
2005年 | 1876篇 |
2004年 | 1783篇 |
2003年 | 1816篇 |
2002年 | 1757篇 |
2001年 | 2068篇 |
2000年 | 1544篇 |
1999年 | 1050篇 |
1998年 | 874篇 |
1997年 | 841篇 |
1996年 | 874篇 |
1995年 | 828篇 |
1994年 | 726篇 |
1993年 | 685篇 |
1992年 | 667篇 |
1991年 | 590篇 |
1990年 | 577篇 |
1989年 | 575篇 |
1988年 | 508篇 |
1987年 | 412篇 |
1986年 | 378篇 |
1985年 | 414篇 |
1984年 | 432篇 |
1983年 | 447篇 |
1982年 | 458篇 |
1981年 | 374篇 |
1980年 | 328篇 |
1979年 | 383篇 |
1978年 | 311篇 |
1977年 | 271篇 |
1976年 | 273篇 |
1975年 | 253篇 |
1972年 | 249篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
741.
Prenatal diagnosis of trisomy 20 mosaicism was made in two pregnancies by chromosome analysis of cultured amniotic fluid cells. In both cases, the pregnancy continued to term and a healthy male infant was delivered. Regular assessments up to the age of 6-5 years revealed normal physical and intellectual development in both children. 相似文献
742.
In the case-control study of 118 women with autosomal trisomy identified at prenatal diagnosis and their 442 karyotypically normal matched controls, we found that there was no overall association between risk of trisomy and the presence of vaginal bleeding during pregnancy. However, a lengthy duration of bleeding appears to predict increased risk of trisorny. 相似文献
743.
Citrullinaemia was presumed to be excluded in a fetus at risk by the direct assay of argininosuccinate synthetase in chorionic villi. The diagnosis was confirmed after amniocentesis by normal argininosuccinate synthetase activity in the cultured amniotic fluid cells and by a normal citrulline concentration in the amniotic fluid. The prediction of a normal fetus was confirmed at term by the birth of a non-citrullinaemic boy. 相似文献
744.
745.
沧州炼油厂恶臭污染与防治浅析 总被引:5,自引:0,他引:5
炼油厂在生产过程中产生的废气易引起环境恶臭污染,通过对污染源进行治理,加强生产管理,杜绝无组织排放,实行有效监督是防止恶臭污染的关键。 相似文献
746.
747.
748.
Bosch J 《Die Naturwissenschaften》2002,89(12):575-578
Female midwife toads (genus Alytes) emit highly variable reciprocal calls of unclear function prior to and during courtship. In some species, female-female competition, expressed as physical fighting, has been reported. Males of Majorcan midwife toads (Alytes muletensis) show phonotactic response to female calls, and females of Iberian midwife toads (Alytes cisternasii) respond differently according to the male call characteristics. In this study, I test the hypothesis of female-female acoustic competition as an additional function of female reciprocal calls. Playback tests indicate that female calls are not clearly involved in female acoustic competition in the Iberian midwife toad, therefore female calls could be directed at males rather than towards competitive females. 相似文献
750.