全文获取类型
收费全文 | 43044篇 |
免费 | 472篇 |
国内免费 | 595篇 |
专业分类
安全科学 | 1365篇 |
废物处理 | 1957篇 |
环保管理 | 5589篇 |
综合类 | 6721篇 |
基础理论 | 11400篇 |
环境理论 | 21篇 |
污染及防治 | 11585篇 |
评价与监测 | 2871篇 |
社会与环境 | 2319篇 |
灾害及防治 | 283篇 |
出版年
2023年 | 188篇 |
2022年 | 437篇 |
2021年 | 440篇 |
2020年 | 321篇 |
2019年 | 394篇 |
2018年 | 669篇 |
2017年 | 659篇 |
2016年 | 1036篇 |
2015年 | 812篇 |
2014年 | 1235篇 |
2013年 | 3553篇 |
2012年 | 1484篇 |
2011年 | 1955篇 |
2010年 | 1592篇 |
2009年 | 1674篇 |
2008年 | 1987篇 |
2007年 | 2043篇 |
2006年 | 1772篇 |
2005年 | 1480篇 |
2004年 | 1414篇 |
2003年 | 1498篇 |
2002年 | 1357篇 |
2001年 | 1711篇 |
2000年 | 1214篇 |
1999年 | 731篇 |
1998年 | 522篇 |
1997年 | 513篇 |
1996年 | 554篇 |
1995年 | 616篇 |
1994年 | 610篇 |
1993年 | 520篇 |
1992年 | 517篇 |
1991年 | 481篇 |
1990年 | 532篇 |
1989年 | 462篇 |
1988年 | 418篇 |
1987年 | 394篇 |
1986年 | 335篇 |
1985年 | 356篇 |
1984年 | 395篇 |
1983年 | 383篇 |
1982年 | 370篇 |
1981年 | 352篇 |
1980年 | 284篇 |
1979年 | 321篇 |
1978年 | 269篇 |
1977年 | 201篇 |
1975年 | 215篇 |
1972年 | 212篇 |
1971年 | 186篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
361.
362.
Erwin W. Müller 《Die Naturwissenschaften》1970,57(5):222-230
363.
364.
365.
366.
Dr. Waldo Sepulveda Peter Nicolaidis Jean Hollingsworth Nicholas M. Fisk 《黑龙江环境通报》1995,15(2):193-197
The fetal gall bladder can now be easily identified during the second and third trimesters using high-resolution ultrasonography. In this report we present eight fetuses with an enlarged gall bladder detected on prenatal ultrasonography at a mean gestational age of 24.6 weeks (range 19–31 weeks). Additional ultrasonographic findings were present in four cases: fetal anomalies and intrauterine growth retardation in three and polyhydramnios in one. Of those cases associated with fetal anomalies, one woman underwent amniocentesis at 21 weeks revealing trisomy 18. The other two declined prenatal karyotyping; neonatal karyotyping revealed trisomy 13 in one and trisomy 18 in the other. Although an enlarged fetal gall bladder can be a normal variant in the second and third trimesters, the prenatal detection of cholecystomegaly should prompt a search for associated anomalies and other markers of aneuploidy. If found, prenatal karyotyping should be considered. 相似文献
367.
Mary C. Phelan Ph.D. Robert A. Saul Thompson A. Gailey Jr Steven A. Skinner 《黑龙江环境通报》1995,15(3):274-277
Mosaicism for the Wolf-Hirschhorn syndrome, del(4)(p16), is extremely rare and has not been reported in association with a numerical chromosome abnormality. We report the prenatal diagnosis of mosaic del(4)(p16) and non-mosaic trisomy 21 in a 16-week female fetus. The pregnancy ended in spontaneous abortion at 34 weeks secondary to fetal demise. The fetus had features of both 4p – and trisomy 21. 相似文献
368.
Forty-two open neural tube defects (NTDs) were identified in our series of 7440 amniocenteses tested between 11 and 15 weeks of gestation. Using a cut-off of ≥2.0 MOM, the detection rate for open NTDs was 95 per cent; 100 per cent each for anencephaly and spina bifida; and 78 per cent for encephalocele. Two encephaloceles had AFP levels less than 2.0 MOM and negative AChEs. Thirty-four (81 per cent) of these NTDs were tested between 13 and 15 weeks and 8 (19 per cent) before 13 weeks. There were 0.6 per cent false positives by AFP (excluding serious abnormalities and fetal death) and 0.1 per cent after AChE. The likelihood of an open NTD after an elevated AFP (≥2.0 MOM) was 24 and 77 per cent for any serious abnormality. These results, when combined with an earlier study, indicate that amniotic fluid AFP appears to be as sensitive a test for open NTDs between 13 and 15 weeks as between 16 and 20 weeks. Additional experience is necessary to determine this before 13 weeks. 相似文献
369.
M. Peter Marinkovich MD Guerrino Meneguzzi Robert E. Burgeson Claudine Blanchet-Bardon Karen A. Holbrook Lynne T. Smith Angela M. Christiano Jean-Paul Ortonne 《黑龙江环境通报》1995,15(11):1027-1034
Herlitz junctional epidermolysis bullosa (HJEB) is a severe blistering disorder which usually results in death during infancy. We have previously shown that the anchoring filament protein laminin-5 (kalinin/nicein), which mediates keratinocyte attachment and dermal–epidermal cohesion, is abnormally expressed in individuals with HJEB. Laminin-5 was detected by Western blot analysis in amniotic fluid from 44 consecutive normal secondtrimester control pregnancies, but was undetectable in second-trimester amniotic fluid from four pregnancies with fetuses affected by HJEB. In one case of severe non-Herlitz JEB, laminin-5 was detected in both amniotic fluid and skin. In human amniotic fluid, the laminin-5 a3 subunit was processed to a major 165 kD species and a minor 145 kD species and the β2 subunit was partially processed to 105 kD. Although laminin-5 was covalently associated with laminin-6 (K-laminin) in amniotic membrane, no covalent interaction was detected in amniotic fluid. Laminin-5 from amniotic fluid strongly supported keratinocyte attachment. These results suggest that Western blot analysis of second-trimester amniotic fluid is useful in determining the prenatal diagnosis of HJEB and that laminin-5 may serve a physiologically important function in amniotic fluid. 相似文献
370.
Trisomy 10 was detected at amniocentesis undertaken following observation of fetal nuchal oedema. This is the first report of fetal trisomy 10 in association with nuchal oedema. The physical features of fetal trisomy 10 are described. 相似文献