全文获取类型
收费全文 | 31706篇 |
免费 | 295篇 |
国内免费 | 242篇 |
专业分类
安全科学 | 719篇 |
废物处理 | 1271篇 |
环保管理 | 3581篇 |
综合类 | 6772篇 |
基础理论 | 7893篇 |
环境理论 | 17篇 |
污染及防治 | 7959篇 |
评价与监测 | 2005篇 |
社会与环境 | 1888篇 |
灾害及防治 | 138篇 |
出版年
2022年 | 236篇 |
2021年 | 220篇 |
2019年 | 227篇 |
2018年 | 427篇 |
2017年 | 462篇 |
2016年 | 666篇 |
2015年 | 528篇 |
2014年 | 790篇 |
2013年 | 2258篇 |
2012年 | 904篇 |
2011年 | 1327篇 |
2010年 | 1073篇 |
2009年 | 1108篇 |
2008年 | 1328篇 |
2007年 | 1372篇 |
2006年 | 1196篇 |
2005年 | 1010篇 |
2004年 | 1009篇 |
2003年 | 997篇 |
2002年 | 970篇 |
2001年 | 1184篇 |
2000年 | 811篇 |
1999年 | 528篇 |
1998年 | 358篇 |
1997年 | 402篇 |
1996年 | 419篇 |
1995年 | 448篇 |
1994年 | 449篇 |
1993年 | 382篇 |
1992年 | 394篇 |
1991年 | 387篇 |
1990年 | 386篇 |
1989年 | 357篇 |
1988年 | 307篇 |
1987年 | 301篇 |
1986年 | 290篇 |
1985年 | 297篇 |
1984年 | 307篇 |
1983年 | 301篇 |
1982年 | 293篇 |
1981年 | 260篇 |
1980年 | 240篇 |
1979年 | 243篇 |
1978年 | 221篇 |
1977年 | 227篇 |
1976年 | 182篇 |
1975年 | 189篇 |
1974年 | 207篇 |
1973年 | 189篇 |
1972年 | 178篇 |
排序方式: 共有10000条查询结果,搜索用时 37 毫秒
121.
The sensitivity of an integrated model to assess the potential for wind-borne spread of foot-and-mouth disease (FMD) to variations
in key parameters controlling different physical and biological processes was evaluated. The estimated number of farms at
risk is sensitive to the virus strain used and the accompanying effective contact rate. The C Noville strain increased the
estimated number of exposed farms ranked as high and medium risk of being infected by a factor of 5, compared to the baseline,
based on the O UKG 2001 strain. The inclusion of a model for biological ageing of the virus can also have a significant effect
on the concentration patterns arising from transport and dispersion of the virus. Its inclusion has the practical advantage
of markedly reducing the time required for the calculations. The estimated number of farms affected by exposure to high and
medium virus concentrations is not grossly sensitive to attenuation caused by temperature or relative humidity effects. Changes
in susceptibility to infection, as determined by the parameter θ in the exposure-risk model, does not change the configuration of the virus plumes, but it does change the distribution of
farms at risk by risk category. These findings suggest that a good understanding of characteristics (excretion rates from
infected animals, susceptibility of different species to infection, virus survival, etc.) of the virus strain involved in
an FMD outbreak is necessary to provide a reliable assessment of the risk of wind-borne spread. In the event of an incursion
of FMD, provision for laboratory studies on the virus will be an essential component of the disease response and should be
factored into contingency plans.
相似文献
X. YangEmail: |
122.
123.
124.
125.
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
126.
Sofie Adolfsson Jörby 《Journal of Environmental Planning and Management》2002,45(2):219-244
Four small- to medium-sized municipalities in the south-east of Sweden were chosen for a 5-year study of their Local Agenda 21 (LA21) processes. The study shows that the LA21 processes have instigated many new ideas, brought fields together and introduced new subjects into the municipal world. In the decisions of the local governments environmental considerations are treated seriously. There are signs of an extended dialogue and of public influence, especially within fields where citizens are directly involved. LA21 does not seem to have great influence on which natural resources are dealt with, but does on how they are dealt with. New stakeholders within and outside the municipal organization have been identified through the LA21 processes, and more comprehensive ways of solving problems and a positive climate for testing new ideas have been created. In these respects LA21 has been and will be a significant support to the development of appropriate natural resource management at the local level. 相似文献
127.
128.
Community evacuation following a chlorine release, Mississippi 总被引:1,自引:0,他引:1
On 7th September 1986, four miles north of Collins, Mississippi, a train transporting chlorine derailed. Two cars ruptured and gas escaped. As a result, 100 families were evacuated. To study the evacuation process, we conducted person-to-person interviews with sixty-two families staying in the evacuation center. Only 52.5% of the families received their first directive to evacuate directly from police or other officials. Delays in evacuating tended to be shorter when people were warned by the police and were told the reason for evacuating. Lack of personal transportation and preexisting health problems resulted in delays in evacuation. Concerns about evacuation included fear of looting, lack of a place to go, lack of transportation, difficulty in moving with children and elderly persons, and the need to take care of pets. One third of the interviewees reported feeling panic. Community evacuation procedures would be improved if: (1) officials contact all households directly; (2) the warning message addresses people's concerns; and (3) transportation is provided. 相似文献
129.
130.
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