全文获取类型
收费全文 | 47818篇 |
免费 | 381篇 |
国内免费 | 523篇 |
专业分类
安全科学 | 982篇 |
废物处理 | 2416篇 |
环保管理 | 6041篇 |
综合类 | 7734篇 |
基础理论 | 12478篇 |
环境理论 | 12篇 |
污染及防治 | 11737篇 |
评价与监测 | 3495篇 |
社会与环境 | 3609篇 |
灾害及防治 | 218篇 |
出版年
2022年 | 399篇 |
2021年 | 395篇 |
2020年 | 249篇 |
2019年 | 341篇 |
2018年 | 1950篇 |
2017年 | 1866篇 |
2016年 | 1983篇 |
2015年 | 794篇 |
2014年 | 1048篇 |
2013年 | 3043篇 |
2012年 | 1625篇 |
2011年 | 2864篇 |
2010年 | 2009篇 |
2009年 | 2011篇 |
2008年 | 2506篇 |
2007年 | 2924篇 |
2006年 | 1515篇 |
2005年 | 1372篇 |
2004年 | 1415篇 |
2003年 | 1444篇 |
2002年 | 1389篇 |
2001年 | 1519篇 |
2000年 | 1029篇 |
1999年 | 648篇 |
1998年 | 489篇 |
1997年 | 472篇 |
1996年 | 527篇 |
1995年 | 561篇 |
1994年 | 511篇 |
1993年 | 467篇 |
1992年 | 435篇 |
1991年 | 437篇 |
1990年 | 421篇 |
1989年 | 378篇 |
1988年 | 372篇 |
1987年 | 352篇 |
1986年 | 309篇 |
1985年 | 334篇 |
1984年 | 381篇 |
1983年 | 371篇 |
1982年 | 353篇 |
1981年 | 347篇 |
1980年 | 292篇 |
1979年 | 307篇 |
1978年 | 246篇 |
1977年 | 230篇 |
1976年 | 204篇 |
1975年 | 215篇 |
1973年 | 208篇 |
1972年 | 214篇 |
排序方式: 共有10000条查询结果,搜索用时 609 毫秒
41.
S. S. S. Sarma Saúl Avelino Rivera Fabiola Elizalde Hinojosa S. Nandini 《Russian Journal of Ecology》2007,38(5):353-362
We tested separately the effect of two taxonomically related rotifers (B. patulus and B. macracanthus) on the population dynamics of another species (A. fissa) at low (0.5 ×10 6) and high food levels (1.5 × 106 cells/ml of Chlorella vulgaris) using different inoculation densities (0–100%). We also quantified the impact of A. fissa on the two brachionid species. Regardless of the presence of the competing species, an increase in the availability of food
led to increase in the abundances of the three rotifers. The population growth of B. patulus, B. macracanthus, or A. fissa was affected negatively when cultured together with another species. An increase in the initial density of any one of the
competing species became advantageous to maintain a certain population size. At a low algal food level, B. patulus was able to suppress A. fissa more strongly than B. macracanthus. On the other hand, at a high food level, B. macracanthus suppressed the population of A. fissa more strongly than B. patulus. Peak population densities for A. fissa varied from about 150 to 1000 ind./ml, depending on food density and the presence of competitors. The rate of population
increase (r) of A. fissa, B. patulus, and B. macracanthus increased with an increase in food availability but decreased with increasing initial density of the competitor. Both Brachionus spp. experienced negative growth rates in the presence of A. fissa, especially at a high initial density of the latter.
Published in Russian in Ekologiya, 2007, Vol. 38, No. 5, pp. 381–390.
The article was submitted by the authors in English. 相似文献
42.
43.
44.
E Enan I G Berberian S el-Fiki M el-Masry O H Enan 《Journal of environmental science and health. Part. B》1987,22(2):149-170
Male Baladi rabbits were acutely and sub-chronically intoxicated with cyanofenphos and profenophos. The levels of cholesterol, triglycerides, B-lipoproteins and total proteins were determined in the serum, brain, spinal cord and sciatic nerve of rabbits. Moreover, the activities of alkaline phosphatase, acid phosphatase and glutamic-pyruvic transaminase were determined in the liver of the animals. The whole studies revealed that the biochemical constituents were highly affected by the tested insecticides. Also, the liver function suffered from adverse effects of the tested insecticides. 相似文献
45.
S. N. Goroshkevich 《Russian Journal of Ecology》2008,39(3):168-175
A statistical analysis of interannual variation in a set of vegetative and generative characters over 13 years has been performed to characterize the growth and seed production dynamics of the Siberian stone pine (Pinus sibirica Du Tour) in the southeast of the forest zone in western Siberia. The results have shown that the range of fluctuations in most of vegetative characters is ordinary and their distribution is close to normal. The range of fluctuations in many generative characters is enormous (from 0 to +∞), and the distribution of their values is usually skewed, with low values being recorded several times more frequently than high values. Most variable are the proportion of abortive cones and other characters that are determined mainly in the spring of the pollination year. These characters account for a very high level of variation in the total seed production. 相似文献
46.
Tanay B. Yıldırım Tutku Ak Zuhal Ölmez 《Environment, Development and Sustainability》2008,10(6):871-881
While the world is going into different tourism expectations, the tourism understanding in Turkey is defined as tourism in the sea-sand-sun triangle. However, it is possible to contribute to the income and local development of the indigenous people by developing nature-based tourism. Besides, with the sustainable use and preservation of the natural-cultural assets, the damage of the traditional tourism industry on the natural and cultural environment could be reduced. In this study, it is aimed to bring up the nature-based tourism concept in Çanakkale by evaluating the nature-based tourism industry in the general of Turkey and assessing the natural-cultural resources that Çanakkale comprehends. The most important areas that have a nature-based tourism potential in Çanakkale and the tourism activities that are most suitable for these areas have been determined. 相似文献
47.
Collections made in the course of long-term field studies on ecology of the northern mole vole Ellobius talpinus Pall. in the Ural Region and neighboring areas (more than 2000 individuals from 24 points of the species range) were used
to analyze geographic variation in its coat color (color morphs). On the basis of long-term observations (1985–1999) on marked
animals from a polymorphic population (Kurtamyshskii raion, Kurgan oblast), the life spans of males and females and the dependence
of life span on population density and structure were estimated in animals of different color morphs. Each color morph of
E. talpinus was shown to have specific features of the seasonal dynamics of age structure and migrations. 相似文献
48.
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
49.
50.
We examined the impact of seven species of mobile mushroom corals (Fungiidae) on the community structure of sheltered reef slopes in terms of their patterns of migration, habitat use and competition with other benthic organisms. On fringing reefs at Eilat, Red Sea, polyps detached at 1 to 6 cm length, and grew to 11–55 cm length. Attached mushroom corals were oriented vertically in reef cavities. Detached corals migrated downward on the reef slope and onto rubble or soft substratum at the reef base, at 29 to 71 cmyr–1. Mobility decreased with corallum size and extent of undersurface ornamentation. In aquaria, small corals righted themselves and migrated up to 6 cm d–1 by nocturnally inflating and pushing their tissues against the substratum. Autonomous coral behavior and storm-generated water motion appeared to account for most fungiid mobility at Eilat. Mushroom corals did not damage each other upon contact, even in multi-species aggregations, but unilaterally damaged non-fungiid scleractinian corals. Their dominance during contact interactions retards overgrowth by larger attached scleractinians, and mobility allows them to colonize soft substrata not accessible to most other reef corals. 相似文献