全文获取类型
收费全文 | 10569篇 |
免费 | 125篇 |
国内免费 | 227篇 |
专业分类
安全科学 | 276篇 |
废物处理 | 543篇 |
环保管理 | 861篇 |
综合类 | 1849篇 |
基础理论 | 2489篇 |
环境理论 | 9篇 |
污染及防治 | 3287篇 |
评价与监测 | 892篇 |
社会与环境 | 648篇 |
灾害及防治 | 67篇 |
出版年
2023年 | 120篇 |
2022年 | 311篇 |
2021年 | 296篇 |
2020年 | 184篇 |
2019年 | 178篇 |
2018年 | 346篇 |
2017年 | 381篇 |
2016年 | 512篇 |
2015年 | 348篇 |
2014年 | 531篇 |
2013年 | 830篇 |
2012年 | 570篇 |
2011年 | 714篇 |
2010年 | 473篇 |
2009年 | 438篇 |
2008年 | 605篇 |
2007年 | 574篇 |
2006年 | 429篇 |
2005年 | 415篇 |
2004年 | 396篇 |
2003年 | 366篇 |
2002年 | 293篇 |
2001年 | 219篇 |
2000年 | 125篇 |
1999年 | 107篇 |
1998年 | 55篇 |
1997年 | 62篇 |
1996年 | 47篇 |
1995年 | 78篇 |
1994年 | 65篇 |
1993年 | 34篇 |
1992年 | 44篇 |
1991年 | 49篇 |
1990年 | 46篇 |
1989年 | 40篇 |
1988年 | 30篇 |
1987年 | 24篇 |
1986年 | 36篇 |
1985年 | 24篇 |
1984年 | 24篇 |
1983年 | 27篇 |
1982年 | 28篇 |
1981年 | 20篇 |
1979年 | 18篇 |
1966年 | 21篇 |
1965年 | 16篇 |
1964年 | 22篇 |
1958年 | 21篇 |
1957年 | 15篇 |
1956年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Matthew Bates Paolo Bruno Mariangela Caputi Maurizio Caselli Gianluigi de Gennaro Maria Tutino 《Atmospheric environment (Oxford, England : 1994)》2008,42(24):6144-6151
The technique of thermal desorption (TD)–GC/MS was evaluated for measuring airborne, 4–6 ring polycyclic aromatic hydrocarbons (PAHs) collected onto quartz filters. TD provides a more readily automated and sensitive alternative to traditional solvent extraction, decreasing the time/cost of analysis and reducing the risk of analyte loss or sample contamination. The developed method was successfully applied to the analysis of PAH standard solutions loaded on sorbent tubes packed with quartz wool and the graphitized carbon black sorbent Carbograph2. The optimized method showed high desorption efficiency over the whole range of target PAHs with good precision, linearity and sensitivity. The proposed method was verified on an urban dust Standard Reference Material (SRM 1649a); the experimentally determined concentrations agreed with the certified ranges (95% confidence limit) for all target compounds except benzo[a]anthracene, which fell just outside the narrow certified range. The desorption efficiency and the reproducibility of the method was evaluated by analysing pieces of real sample filters sampled from urban air for a period of 24 h. The results confirmed the homogeneity of the filter and showed high recovery efficiencies for all target PAHs. 相似文献
2.
Cornus stolonifera, Salix petiolaris, and Spiraea alba
clones already located within the corridor of an electrical power line. To
establish the efficiency of treatments, we examined the statistical
differences of growth traits between species and treatments.
An analysis of the effects of layering shows, after the first growth season,
differences for all growth traits in only one species, Spiraea alba.
After the second growth season, we observed the development of new aerial
stems. Layering favors horizontal expansion of shrubs over height
development. The third year after treatment, the effect of layering is
reduced except for Cornus stolonifera, which continuously increases,
as shown by the significant progression of the clone issued from the layer
even five years after treatments. With the cutting back technique, we
expected a distinct vertical growth of the shrubs at the expense of
increasing the crown diameter. This technique would be best associated with
the rejuvenation of clones, followed by a layering of new shoots to allow a
horizontal expansion of the shrubs. Therefore, the formation of a dense shrub
community by layering should be considered a valuable approach for the
biological control of undesirable trees in powerline rights-of-way. 相似文献
3.
A Barba M A Camara S Navarro Garcia C Sanchez-Fresneda N Lopez de Hierro A Acebes 《Journal of environmental science and health. Part. B》1991,26(3):323-332
Residues of Bromopropylate were determine in artichokes, strawberries and beans after foliar spray of acaricide at two rates. The rates used were 1 g/l formulated product (normal recommended) and 1.5 g/l. The residue levels of bromopropylate in the three crops after 14 days were lower than 0.7 ppm and did not exceed the Maximum Residual Level (MRL) recommended by FAO. In the artichokes and strawberries, the total concentration of residues decreased by 50% of the initial level after 2-3 days. Only trace levels of the bromopropylate residues (less than 0.01 ppm) were detected in the "hearts" of the artichokes. Bromopropylate residues in the green beans were also less than 0.8 ppm after the first day of foliar spraying. The kinetic of degradation occurred in two different steps. In the first step (4-6 days) the dissipation of bromopropylate was faster whereas in the second step (7-14 days) the loss of residues was much slower. 相似文献
4.
The modern theory of biological evolution: an expanded synthesis 总被引:12,自引:2,他引:12
In 1858, two naturalists, Charles Darwin and Alfred Russel Wallace, independently proposed natural selection as the basic mechanism responsible for the origin of new phenotypic variants and, ultimately, new species. A large body of evidence for this hypothesis was published in Darwins Origin of Species one year later, the appearance of which provoked other leading scientists like August Weismann to adopt and amplify Darwins perspective. Weismanns neo-Darwinian theory of evolution was further elaborated, most notably in a series of books by Theodosius Dobzhansky, Ernst Mayr, Julian Huxley and others. In this article we first summarize the history of life on Earth and provide recent evidence demonstrating that Darwins dilemma (the apparent missing Precambrian record of life) has been resolved. Next, the historical development and structure of the modern synthesis is described within the context of the following topics: paleobiology and rates of evolution, mass extinctions and species selection, macroevolution and punctuated equilibrium, sexual reproduction and recombination, sexual selection and altruism, endosymbiosis and eukaryotic cell evolution, evolutionary developmental biology, phenotypic plasticity, epigenetic inheritance and molecular evolution, experimental bacterial evolution, and computer simulations (in silico evolution of digital organisms). In addition, we discuss the expansion of the modern synthesis, embracing all branches of scientific disciplines. It is concluded that the basic tenets of the synthetic theory have survived, but in modified form. These sub-theories require continued elaboration, particularly in light of molecular biology, to answer open-ended questions concerning the mechanisms of evolution in all five kingdoms of life.Dedicated to Prof. Dr. Dr. hc mult. Ernst Mayr on the occasion of his 100th birthdayThis revised version was published online in March 2004, with corrections to the caption of Figure 6. 相似文献
5.
6.
7.
8.
9.
10.
We report relatively high citrulline concentration in amniotic fluid of a citrullinemic fetus suggesting that prenatal detection of this condition could be done on this basis in conjunction with a direct or an indirect determination of argininosuccinate synthetase activity in amniotic fluid cells. 相似文献