全文获取类型
收费全文 | 312篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 9篇 |
废物处理 | 6篇 |
环保管理 | 17篇 |
综合类 | 115篇 |
基础理论 | 83篇 |
污染及防治 | 70篇 |
评价与监测 | 12篇 |
社会与环境 | 5篇 |
出版年
2022年 | 2篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 14篇 |
2012年 | 15篇 |
2011年 | 17篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 8篇 |
2007年 | 12篇 |
2006年 | 15篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 11篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1985年 | 3篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1966年 | 7篇 |
1965年 | 3篇 |
1964年 | 4篇 |
1963年 | 4篇 |
1962年 | 5篇 |
1960年 | 2篇 |
1958年 | 3篇 |
1957年 | 3篇 |
1955年 | 4篇 |
1954年 | 2篇 |
1952年 | 2篇 |
1951年 | 3篇 |
1943年 | 2篇 |
1940年 | 2篇 |
1939年 | 2篇 |
1936年 | 1篇 |
1923年 | 1篇 |
1921年 | 1篇 |
排序方式: 共有317条查询结果,搜索用时 15 毫秒
311.
312.
313.
Maternal serum alpha-fetoprotein (AFP) has been reported to be decreased in insulin-dependent diabetes mellitus (IDDM). The objective of the present study was to reinvestigate this finding in detail. Maternal serum levels of AFP, human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) in 114 diabetic women, of whom 84 had IDDM, were compared to those of 19,251 control pregnancies in the second trimester (15th to 20th gestational weeks). The mean body weight at the date of sampling was 73.7 kg in all diabetic women, 72.7 kg in women with IDDM and 68.3 kg in non-diabetic women, respectively. Body weights were significantly (p<0.001) elevated in all diabetic pregnancies. Using weight-adjusted MoM (multiple of the median) values no statistical difference of serum levels in diabetic and non-diabetic pregnant women was found. Median MoM levels were 1.01 (hCG), 1.01 (uE3), 1.06 (AFP) in all diabetic women, and 0.95 (hCG), 0.96 (uE3), 0.96 (AFP) in women with IDDM, respectively. Ignoring adjustment for maternal weight leads to a reduction of all serum parameters in diabetic pregnancies. However, median MoM values of all three analytes are not statistically different when compared to non-diabetic pregnancies. This finding is contrary to the results of former studies from the 1970s and 1980s. It is concluded that progress in insulin adjustment and blood glucose surveillance of diabetic patients on the whole has balanced out serum levels. Therefore adjustment of serum AFP values for diabetic status no longer seems reasonable. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
314.
315.
Ulrich Keppler 《Die Naturwissenschaften》1962,49(19):446-447
316.
H. Borchert H. Seilkopf H. Musso G. Schramm Hans Ulrich 《Die Naturwissenschaften》1955,42(11):351-352
317.
The German biologist August Weismann (1834–1914) proposed that amphimixis (sexual reproduction) creates variability for natural selection to act upon, and hence he became one of the founders of the Neo-Darwinian theory of biological evolution. He is perhaps best known for what is called “Weismann’s Doctrine” or “Weismann’s Barrier” (i.e. the irreversible separation of somatic and germ cell functionalities early during ontogeny in multicellular organisms). This concept provided an unassailable argument against “soft inheritance” sensu Lamarck and informed subsequent theorists that the only “individual” in the context of evolution is the mature, reproductive organism. Herein, we review representative model organisms whose embryology conforms to Weismann’s Doctrine (e.g. flies and mammals) and those that do not (e.g. freshwater hydroids and plants) based on this survey and the Five Kingdoms of Life scheme; we point out that most species (notably bacteria, fungi, protists and plants) are “non-Weismannian” in ways that make a canonical definition of the “individual” problematic if not impossible. We also review critical life history functional traits that allow us to create a matrix of all theoretically conceivable life cycles (for eukaryotic algae, embryophytes, fungi and animals), which permits us to establish where this scheme Weismann’s Doctrine holds true and where it does not. In addition, we argue that bacteria, the dominant organisms of the biosphere, exist in super-cellular biofilms but rarely as single (planktonic) microbes. Our analysis attempts to show that competition among genomic variants in cell lineages played a critical part in the evolution of multicellularity and life cycle diversity. This feature was largely ignored during the formulation of the synthetic theory of biological evolution and its subsequent elaborations. 相似文献