全文获取类型
收费全文 | 563篇 |
免费 | 2篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 4篇 |
废物处理 | 14篇 |
环保管理 | 27篇 |
综合类 | 269篇 |
基础理论 | 108篇 |
环境理论 | 1篇 |
污染及防治 | 102篇 |
评价与监测 | 20篇 |
社会与环境 | 23篇 |
灾害及防治 | 2篇 |
出版年
2018年 | 7篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2013年 | 21篇 |
2012年 | 12篇 |
2011年 | 16篇 |
2010年 | 12篇 |
2009年 | 18篇 |
2008年 | 18篇 |
2007年 | 21篇 |
2006年 | 22篇 |
2005年 | 28篇 |
2004年 | 17篇 |
2003年 | 17篇 |
2002年 | 34篇 |
2001年 | 14篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1996年 | 9篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1968年 | 3篇 |
1967年 | 4篇 |
1966年 | 8篇 |
1965年 | 11篇 |
1964年 | 11篇 |
1963年 | 9篇 |
1962年 | 11篇 |
1961年 | 11篇 |
1960年 | 18篇 |
1959年 | 10篇 |
1958年 | 10篇 |
1957年 | 10篇 |
1956年 | 10篇 |
1955年 | 6篇 |
1954年 | 5篇 |
1951年 | 5篇 |
排序方式: 共有570条查询结果,搜索用时 734 毫秒
521.
522.
The currently discussed model of magnetoreception in birds proposes that the direction of the magnetic field is perceived by radical-pair processes in specialized photoreceptors, with cryptochromes suggested as potential candidate molecules mediating magnetic compass information. Behavioral studies have shown that magnetic compass orientation takes place in the eye and requires light from the blue-green part of the spectrum. Cryptochromes are known to absorb in the same spectral range. Because of this we searched for cryptochrome (CRY) in the retina of European robins, Erithacus rubecula, passerine birds that migrate at night. Here, we report three individually expressed cryptochromes, eCRY1a, eCRY1b, and eCRY2. While eCRY1a and eCRY2 are similar to the cryptochromes found in the retina of the domestic chicken, eCRY1b has a unique carboxy (C)-terminal. In light of the radical-pair model, our findings support a potential role of cryptochromes as transducers for the perception of magnetic compass information in birds. 相似文献
523.
524.
525.
Dr Wiltrud Coerdt Helga Rehder Hans-Jürgen Gebauer Wolfgang Holzgreve Franz Klink Peter Miny Bernt Schulze 《黑龙江环境通报》1988,8(9):647-659
Cardiac defects were studied in five chromosomally abnormal embryos of 10–14 weeks' gestation by free-hand microdissection of hearts measuring 2·5–6 mm in diameter. The type of cardiac malformation alone or in association with other anomalies helped to confirm the chromosome diagnosis established prenatally by chorionic villus sampling or after spontaneous abortion. It was suggestive of a chromosomal disorder in one case in which cytogenetic investigation had failed. 相似文献
526.
527.
528.
529.
530.
Dr. Georg Keckstein Sonja Tschurtz Volker Schneider Wolfgang Mütter Rainer Terinde Wolf-Dietrich Jonatha 《黑龙江环境通报》1990,10(1):59-65
Between October 1985 and February 1989, 49 ultrasound-guided intravascular fetal blood transfusions were performed in 16 patients (14 with rhesus (Rh) isoimmunization, 2 with non-immunologic hydrops fetalis (NIHF)). As an intra-operative complication, perivascular haematoma of the cord occurred in three patients (7 per cent). In two cases, fetal bradycardia necessitated delivery by Caesarean section at 30 and 32 weeks' gestation, respectively. In the third case, fetal bradycardia developed during transfusion, at 31 weeks' gestation, but normalized within 3 min. The baby was delivered as planned at 36 weeks of gestation, after another transfusion at 34 weeks. Dislodgement of the needle tip into perivascular tissue, caused by sudden fetal or maternal movements, is the reason for this complication. The haematoma develops as a result of delayed recognition and continuous transfusion into Wharton' s jelly. Cord haematoma may be diagnosed in time by continuous ultrasound imaging, as illustrated in case 3. To minimize the risk of needle dislodgement during transfusion, sedation of the mother and complete immobilization of the fetus by injecting a short-acting muscle relaxant into the umbilical vessel are recommended. 相似文献