全文获取类型
收费全文 | 25729篇 |
免费 | 182篇 |
国内免费 | 143篇 |
专业分类
安全科学 | 459篇 |
废物处理 | 1098篇 |
环保管理 | 3009篇 |
综合类 | 4825篇 |
基础理论 | 6521篇 |
环境理论 | 9篇 |
污染及防治 | 5838篇 |
评价与监测 | 1796篇 |
社会与环境 | 2427篇 |
灾害及防治 | 72篇 |
出版年
2022年 | 163篇 |
2021年 | 192篇 |
2019年 | 150篇 |
2018年 | 770篇 |
2017年 | 743篇 |
2016年 | 821篇 |
2015年 | 363篇 |
2014年 | 537篇 |
2013年 | 1535篇 |
2012年 | 783篇 |
2011年 | 1495篇 |
2010年 | 1004篇 |
2009年 | 1145篇 |
2008年 | 1430篇 |
2007年 | 1675篇 |
2006年 | 823篇 |
2005年 | 751篇 |
2004年 | 757篇 |
2003年 | 795篇 |
2002年 | 773篇 |
2001年 | 839篇 |
2000年 | 555篇 |
1999年 | 373篇 |
1998年 | 260篇 |
1997年 | 257篇 |
1996年 | 269篇 |
1995年 | 300篇 |
1994年 | 283篇 |
1993年 | 260篇 |
1992年 | 243篇 |
1991年 | 246篇 |
1990年 | 254篇 |
1989年 | 213篇 |
1988年 | 202篇 |
1987年 | 187篇 |
1986年 | 193篇 |
1985年 | 187篇 |
1984年 | 221篇 |
1983年 | 199篇 |
1982年 | 212篇 |
1981年 | 176篇 |
1980年 | 174篇 |
1979年 | 161篇 |
1978年 | 159篇 |
1977年 | 140篇 |
1976年 | 124篇 |
1975年 | 132篇 |
1974年 | 140篇 |
1973年 | 124篇 |
1972年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Tone River supplies most of the water requirements of the Tokyo Metropolitan Area (TMA). Lowering of Tone flow and yearly
fluctuation, however, is causing water shortage along TMA nowadays. This study investigated the future water availability
scenarios under climatic changes. A state-of-the-art approach to utilize the output of several GCM has been demonstrated to
investigate the future water availability scenarios for TMA from the Tone River. An integrated modeling approach for water
balance considering several hydrological risk indices was adopted to quantify the future changes in this case. It is observed
that the future summer precipitation along the Tone basin is going to be increased considerably, while an almost constant
or decreasing trend is observed for winter season. Natural flow availability for winter or spring seasons thus can be crucial
under future scenarios. After reservoir routing, the hydrological risk indices estimated, however, were not found to be changed
significantly due to the presence of a robust reservoir system at the upstream. 相似文献
62.
63.
E. A. Kleshcheva 《Russian Journal of Ecology》2007,38(2):94-100
A method for estimating the current state of plant communities based on the ecological amplitudes of constituent species is proposed. An original program, Fitoindikatsiya, has been developed to compute the indices of disturbance and homogeneity of plant communities from species ecological scale values. The current state of pine forests in the part of Novosibirsk oblast east of the Ob River has been analyzed; slightly, moderately, and severely disturbed zones have been distinguished. 相似文献
64.
65.
66.
We examined the chemical antifouling properties of four sublittoral red algae, Chondrus crispus, Delesseria sanguinea, Osmundea ramosissima, and Polyides rotundus, which are all rarely fouled in the field. Two different approaches were used. Firstly, we tested the effects of lipophilic crude extracts on the settlement behaviour of cyprid larvae of the co-existing barnacle Balanus improvisus. Secondly, in a settlement preference experiment, we tested whether B. improvisus cyprid larvae settle on living algae when given a choice between natural algal surfaces and control surfaces. With this procedure, we were able to test both if the algae inhibit recruitment of cyprids, and if this inhibition is a result of chemistry. The settlement of B. improvisus larvae was strongly inhibited at concentrations estimated to be potentially ecologically relevant for all of the tested extracts. However, only C. crispus significantly inhibited settlement in the preference experiment, even though there was also a tendency for settlement inhibition on P. rotundus and O. ramosissima. In contrast, D. sanguinea seemed to stimulate settlement. This contradiction probably resulted from an extraction of metabolites that naturally occur only inside the alga. However, as this study shows, a combination of settlement assays with whole-cell extracts and preference tests of ecologically relevant fouling organisms on natural algal and control surfaces may be a useful procedure to avoid erroneous conclusions regarding natural antifouling roles of compounds based on settlement assays with only whole-cell extracts. Furthermore, this study also shows that production of inhibitory metabolites may explain the low degree of fouling, especially by B. improvisus, on C. crispus.Communicated by L. Hagerman, Helsingør 相似文献
67.
68.
T. Antoniadi C. Yapijakis P. Kaminopetros C. Makatsoris V. Velissariou D. Vassilopoulos M. B. Petersen 《黑龙江环境通报》2002,22(5):425-429
The presence of maternal cells in fetal samples constitutes a serious potential source for prenatal misdiagnosis. Here we present our approach for detecting maternal cell contamination (MCC) at prenatal diagnosis for eight monogenic disorders (autosomal recessive: β-thalassaemia, sickle-cell anaemia, cystic fibrosis, prelingual deafness; autosomal dominant: achondroplasia, Huntington disease, myotonic dystrophy, neurofibromatosis type I; X-linked: spinobulbar muscular atrophy). Our aim was to apply a simple and low-cost approach, which would easily and accurately provide information on the fetal tissue MCC status. MCC testing was applied to cases of recessive inheritance where the primary mutation screening of the fetus revealed the presence of the maternal mutation, to cases concerning dominant inheritance and to cases of multiple gestation. The potential presence of maternal cells was determined by the amplification of the 3′-HVR/APO B, D1S80, THO1 and VNTRI of vWf polymorphic loci, which have previously demonstrated high heterozygosity in Caucasians. Among 135 prenatal diagnoses, 44 finally needed to be tested for MCC (32.6%). MCC was detected in four cases, where DNA was isolated directly from chorionic villi samples (CVS), and in one case with DNA isolated directly from amniotic fluid (AF). In almost 90% of cases a simple test of one polymorphic locus provided sufficient information about MCC. The choice of the appropriate locus is therefore essential, while the simultaneous screening of both parents provides the means for distinguishing non-informative sites about MCC. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
69.
The situation and the latest findings of forest damage research in Germany are discussed. A newly developed concept for this research is described. This concept allows to identify the drawbacks of the recent damage research concept but also the integration of results compiled up to now. The importance for including natural occurring stress factors such as climate, soil conditions or local situation of individual species is outlined. 相似文献
70.
Indices of abundance and reproduction rate are considered in some groups of aquatic and terrestrial vertebrates from the zones of technogenic disasters. Upon a critical population decline caused by external destructive factors, such as emissions of acute ecotoxicants, the ecophysiological and behavioral compensatory mechanisms are activated, which provide for restoration of the total population size to the optimum within a short period of time. Environmental pollution with substances disturbing the reproductive function has the gravest consequences for animals. In this case, population size may remain fairly high, and, therefore, the effect of enhanced reproduction as a response to population decline does not take place, which eventually leads to a gradual but irreversible destruction of the population. Pathologies of reproduction should be used as a criterion for assessing the state of animals in the zones of technogenic disasters.Translated from Ekologiya, No. 1, 2005, pp. 32–38.Original Russian Text Copyright © 2005 by Shilova, Shatunovskii. 相似文献