全文获取类型
收费全文 | 19697篇 |
免费 | 114篇 |
国内免费 | 262篇 |
专业分类
安全科学 | 206篇 |
废物处理 | 1283篇 |
环保管理 | 2331篇 |
综合类 | 2496篇 |
基础理论 | 5636篇 |
污染及防治 | 4069篇 |
评价与监测 | 1717篇 |
社会与环境 | 2276篇 |
灾害及防治 | 59篇 |
出版年
2023年 | 69篇 |
2022年 | 177篇 |
2021年 | 148篇 |
2020年 | 86篇 |
2019年 | 120篇 |
2018年 | 1697篇 |
2017年 | 1630篇 |
2016年 | 1493篇 |
2015年 | 320篇 |
2014年 | 340篇 |
2013年 | 811篇 |
2012年 | 818篇 |
2011年 | 1854篇 |
2010年 | 1147篇 |
2009年 | 1052篇 |
2008年 | 1446篇 |
2007年 | 1827篇 |
2006年 | 365篇 |
2005年 | 393篇 |
2004年 | 365篇 |
2003年 | 448篇 |
2002年 | 473篇 |
2001年 | 371篇 |
2000年 | 239篇 |
1999年 | 127篇 |
1998年 | 117篇 |
1997年 | 89篇 |
1996年 | 114篇 |
1995年 | 136篇 |
1994年 | 104篇 |
1993年 | 86篇 |
1992年 | 95篇 |
1991年 | 95篇 |
1990年 | 80篇 |
1989年 | 73篇 |
1988年 | 70篇 |
1987年 | 79篇 |
1986年 | 54篇 |
1985年 | 64篇 |
1984年 | 80篇 |
1983年 | 74篇 |
1982年 | 62篇 |
1981年 | 68篇 |
1980年 | 48篇 |
1979年 | 46篇 |
1977年 | 40篇 |
1976年 | 38篇 |
1974年 | 34篇 |
1973年 | 44篇 |
1972年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 640 毫秒
161.
A case is described of the prenatal diagnosis of choroid plexus cysts at 17 weeks' gestation which persisted beyond 36 weeks but could not be detected after delivery. At birth the child was found to have trisomy 18. 相似文献
162.
中国环境镉接触人群低骨密度及肾功能不全的研究 总被引:19,自引:0,他引:19
25年前,Ambio曾载文提出应警惕环境镉污染引起的健康效应.1998年在中国进行了这方面的研究,评价了因食用大米而接触镉人群的前臂骨密度(BMD)和肾功能,发现尿镉(CdU)或血镉(CdB)高的绝经后妇女及血镉(CdB)高的男性,BMD均有所下降.在CdB或CdU与肾功能不全(视黄醇结合蛋白排泄增加)之间也发现了明显的、有统计学意义的剂量-效应关系及剂量-反应关系.第一次报道了日本以外的亚洲地区镉接触人群中存在骨不良效应.本文的意义在于阐明了亚洲的环境镉接触人群中仍存在着与肾和骨(镉的比较严重的有害效应)的联合效应,也讨论了一些欧洲镉接触人群的骨效应. 相似文献
163.
Stanislav N. Gorb 《Die Naturwissenschaften》1999,86(11):552-555
Two main types of joints occur in the damselfly wing: mobile and immobile. Some longitudinal veins (RP2–, RP3&4–, and MP–) are elastically joined with cross veins, whereas other longitudinal veins (IR1+, IR2+, MA+, CuA'+) are firmly joined with cross veins. In this study we mapped the distribution of serial elastic elements in the wing. The
occurrence of resilin, a rubberlike protein, in mobile joints suggests that the automatic twisting mechanism of the leading
edge by aerodynamic force works not by flexibility but by the elasticity of these joints. First, it should result in elastic
energy storage in the distal areas of the wing. Second, serial elastic elements of wing presumably act as dampers of an aerodynamic
force, which are responsible for gradual twisting of the leading edge.
Received: 16 March 1999 / Accepted in revised form: 26 August 1999 相似文献
164.
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
165.
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
166.
167.
168.
169.
170.