全文获取类型
收费全文 | 7086篇 |
免费 | 192篇 |
国内免费 | 1637篇 |
专业分类
安全科学 | 342篇 |
废物处理 | 467篇 |
环保管理 | 550篇 |
综合类 | 2783篇 |
基础理论 | 1378篇 |
环境理论 | 3篇 |
污染及防治 | 2537篇 |
评价与监测 | 368篇 |
社会与环境 | 297篇 |
灾害及防治 | 190篇 |
出版年
2023年 | 80篇 |
2022年 | 229篇 |
2021年 | 187篇 |
2020年 | 132篇 |
2019年 | 130篇 |
2018年 | 234篇 |
2017年 | 221篇 |
2016年 | 238篇 |
2015年 | 292篇 |
2014年 | 348篇 |
2013年 | 659篇 |
2012年 | 412篇 |
2011年 | 488篇 |
2010年 | 392篇 |
2009年 | 417篇 |
2008年 | 445篇 |
2007年 | 422篇 |
2006年 | 350篇 |
2005年 | 283篇 |
2004年 | 250篇 |
2003年 | 275篇 |
2002年 | 266篇 |
2001年 | 328篇 |
2000年 | 257篇 |
1999年 | 209篇 |
1998年 | 155篇 |
1997年 | 150篇 |
1996年 | 134篇 |
1995年 | 150篇 |
1994年 | 119篇 |
1993年 | 106篇 |
1992年 | 78篇 |
1991年 | 67篇 |
1990年 | 41篇 |
1989年 | 38篇 |
1988年 | 35篇 |
1987年 | 20篇 |
1986年 | 23篇 |
1985年 | 17篇 |
1984年 | 23篇 |
1983年 | 25篇 |
1982年 | 31篇 |
1981年 | 19篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1975年 | 12篇 |
1973年 | 9篇 |
1972年 | 10篇 |
排序方式: 共有8915条查询结果,搜索用时 328 毫秒
131.
In Hydra vulgaris at the level of dissociated single cells endodermal cells adhere to each other more readily than to ectodermal cells at the
initial adhesion. The time required for adhesion to occur between two adjacent cells is shorter for both endodermal and ectodermal
homotypic cell adhesions once the initial adhesion of the first pair of cells has been established. It is confirmed that contact
of an aggregated pair with additional homotypic cells facilitates the occurrence of homotypic adhesions; heterotypic adhesions
are discouraged. This suggests that adhesion of homotypic cells contributes to an increased readiness for subsequent homotypic
cells to adhere.
Received: 25 August 1999 / Accepted in revised form: 11 January 2000 相似文献
132.
Zhou Zai zhi 《环境科学学报(英文版)》1999,11(2):174-180
1IntroductionHighlyproductivelanduseresultsinacontinuouschangeoflandscapesinruralareas.Undertheimpactofcropproductmarkets,lan... 相似文献
133.
134.
揭示了农业污染纠纷的内涵,提出了处理农业污染纠纷的4个“支撑点”,即运用农业技术先行界定,运用监测数据科学鉴证;运用因果关系逻辑推定,强化环境管理,疏通综合处理渠道等。 相似文献
135.
Numerous studies support that biodiversity predict most to ecosystem functioning, but whether other factors display a more significant direct impact on ecosystem functioning than biodiversity remains to be studied. We investigated 398 samples of the phytoplankton phosphorus resource use efficiency (RUEP = chlorophyll-a concentration/dissolved phosphate) across two seasons in nine plateau lakes in Yunnan Province, China. We identified the main contributors to phytoplankton RUEP and analyzed their potential influences on RUEP at different lake trophic states. The results showed that total nitrogen (TN) contributed the most to RUEP among the nine lakes, whereas community turnover (measured as community dissimilarity) explained the most to RUEP variation across the two seasons. Moreover, TN also influenced RUEP by affecting biodiversity. Species richness (SR), functional attribute diversity (FAD2), and dendrogram-based functional diversity (FDc) were positively correlated with RUEP in both seasons, while evenness was negatively correlated with RUEP at the end of the rainy season. We also found that the effects of biodiversity and turnover on RUEP depended on the lake trophic states. SR and FAD2 were positively correlated with RUEP in all three trophic states. Evenness showed a negative correlation with RUEP at the eutrophic and oligotrophic levels, but a positive correlation at the mesotrophic level. Turnover had a negative influence on RUEP at the eutrophic level, but a positive influence at the mesotrophic and oligotrophic levels. Overall, our results suggested that multiple factors and nutrient states need to be considered when the ecosystem functioning predictors and the biodiversity-ecosystem functioning relationships are investigated. 相似文献
136.
137.
B. Sikkema-Raddatz R. H. Sijmons M. B. Tan-Sindhunata A. Y. Van Der Veen R. Brunsting B. De Vries J. R. Beekhuis D. J. Bekedam B. Van Aken B. De Jong 《黑龙江环境通报》1995,15(5):467-473
We report two cases of apparently balanced complex de novo chromosomal rearrangements (BCCR) detected prenatally at 17 weeks and 10 weeks of gestation, respectively. Chromosomes were studied using GTG-banding and fluorescent in situ hybridization (FISH). In one case four chromosomes and in the other case three chromosomes were involved in the rearrangements. One of the pregnancies was terminated and no external or internal abnormalities were detected at autopsy. The other pregnancy continued to term. Level III ultrasound examination showed no abnormalities. The child is now 3 years old and has neither congenital anomalies nor evidence of delayed psychomotor development. 相似文献
138.
139.
140.
Reverse phase HPLC of radioactive globin chains has been compared to classical carboxy methyl cellulose chromatography for the prenatal diagnosis of β thalassaemia. The two methods correlated highly (r = 0.97 p < 0.0005) and provided an identical diagnosis for 40 fetal blood samples of fetuses homozygous or heterozygous for β thalassaemia. The HPLC procedure was much faster and required fewer biochemical steps (no globin preparation). It was at least as accurate and more sensitive than the classical chromatography. A single column can be used for 150 analyses and is always ready to be used. Last but not least it is much less expensive than CMC chromatography. 相似文献