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191.
Pregnancy outcome after transcervical cvs with a flexible biopsy forceps: Evaluation of risk factors
The pregnancy outcome of 1936 women who had transcervical chorionic villus sampling (CVS) with a flexible biopsy forceps was evaluated. Follow-up until 4 weeks after delivery was 99.4 per cent. Various patient- and procedure-related risk factors for spontaneous loss (fetal or neonatal death) were analysed using stepwise logistic regression analysis. The overall spontaneous loss rate was 4.5 per cent. Factors found to be significantly associated with spontaneous loss were quantity of villi ≤ 15 mg (relative risk (RR) 2.13), a history of first-trimester miscarriage (RR 1.87) or delivery between 16 and 27 weeks (RR 3.87), cervical culture positive for anaerobes (RR 4.52) or group B streptococcus (RR 3.62), post-procedural bleeding >3 days (RR 1.99), and multiple insertions (RR 2.64). Significant differences in loss rates between individual operators were found. A learning effect was not present. There were no infants born with terminal transversal limb anomalies in our series. 相似文献
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Rosen Johannes Fichtner Wolf Rentz Otto 《Mitigation and Adaptation Strategies for Global Change》2004,9(2):121-146
Determining adequate baselinesis a major methodological problem whenquantifying emissions reductions achievedwith the project-based flexibilitymechanisms. Possible methodologies forbaseline setting may be classified intomulti-project and project-specificapproaches. While multi-project approachesprovide baselines for a series of typicalprojects within a certain geographicregion, a sector, or a load range,project-specific (orproject-by-project/single-project)approaches only cover one specific project.Project-by-project baseline approaches havebeen tested extensively within theActivities Implemented Jointly (AIJ) pilotphase; multi-project methodologies, on theother hand, have only rarely been applieddue to the (perceived) political andeconomic complexity of the issue, whichmakes the process of introducingstandardised baselines a very sensitivetask. In particular, there is a lack ofmulti-project baseline approaches takingadvantage of optimising computer modelswithin the electricity sector, even thoughother fields of research have made use ofsuch models quite successfully in the past.Experiences made in the PROBASE projectwith the calculation of standardised,aggregated multi-project baselines forJI/CDM projects using optimising energysystem models are illustrated in this paperfor South Africa, Russia, and Indonesia.Increased transparency and credibility ofstandardised approaches along withpotentially lower transaction costs areidentified as the main arguments for theiruse and further development. In addition,the text gives recommendations wheremodel-based baseline standardisation canpreferentially be applied. 相似文献
199.
Assessing the carbon balance of circumpolar Arctic tundra using remote sensing and process modeling. 总被引:1,自引:0,他引:1
Stephen Sitch A David McGuire John Kimball Nicola Gedney John Gamon Ryan Engstrom Annett Wolf Qianlai Zhuang Joy Clein Kyle C McDonald 《Ecological applications》2007,17(1):213-234
This paper reviews the current status of using remote sensing and process-based modeling approaches to assess the contemporary and future circumpolar carbon balance of Arctic tundra, including the exchange of both carbon dioxide and methane with the atmosphere. Analyses based on remote sensing approaches that use a 20-year data record of satellite data indicate that tundra is greening in the Arctic, suggesting an increase in photosynthetic activity and net primary production. Modeling studies generally simulate a small net carbon sink for the distribution of Arctic tundra, a result that is within the uncertainty range of field-based estimates of net carbon exchange. Applications of process-based approaches for scenarios of future climate change generally indicate net carbon sequestration in Arctic tundra as enhanced vegetation production exceeds simulated increases in decomposition. However, methane emissions are likely to increase dramatically, in response to rising soil temperatures, over the next century. Key uncertainties in the response of Arctic ecosystems to climate change include uncertainties in future fire regimes and uncertainties relating to changes in the soil environment. These include the response of soil decomposition and respiration to warming and deepening of the soil active layer, uncertainties in precipitation and potential soil drying, and distribution of wetlands. While there are numerous uncertainties in the projections of process-based models, they generally indicate that Arctic tundra will be a small sink for carbon over the next century and that methane emissions will increase considerably, which implies that exchange of greenhouse gases between the atmosphere and Arctic tundra ecosystems is likely to contribute to climate warming. 相似文献
200.
Georgios Tsounis Sergio Rossi Maria Aranguren Josep-Maria Gili Wolf Arntz 《Marine Biology》2006,148(3):513-527
Red coral (Corallium rubrum, L. 1758) is an over-exploited Mediterranean gorgonian. The gonadal development cycle of this gorgonian is examined at the
Costa Brava (NW Mediterranean) taking into account for the first time colony size, depth and spatial horizontal variability.
This study compares the gonad development and fertility in two colony size classes (colonies <6-cm height, and >10-cm height,
both at 40–45-m depth), and two populations at different depths (16–18-m depth, and 40–45-m depth, both consisting of <6-cm
high colonies) in a 15-month period. The fertility of seven size classes (<2 cm to >12 cm high colonies, in 2 cm intervals)
was examined in the deep population, where large colonies were present. Furthermore, reproductive output was compared in 6
populations (distributed along more than 70-km coastline) one month before spawning (June). Red coral was found to be dioecious
and gonochoric with a sex ratio of 1:1, which differs from other NW Mediterranean populations. On the other hand, fertility
of different size classes indicates that small colonies of 2-cm height already produce gonads, which is in line with previous
studies. Female and male polyp fertility and sperm sac size increase significantly with colony size [sperm sac diameter: 476±144 μm
(mean±SD) and 305±150 μm in the >10-cm and <6-cm height colonies, respectively), whereas no significant effect on oocyte diameter
was found (oocyte diameter: 373.7±18.7 μm). Depth staggered spawning, that is, an earlier release of gonads in the shallow
populations, was observed in summer 2003, coinciding with the highest temperature gradient between shallow and deep water
during the study period. Colonies of <6-cm height were significantly less fertile than colonies >12 cm, thus the recommendation
of this study is that a minimum height should be incorporated into fishing regulations. The six studied populations at the
Costa Brava showed a comparable reproductive potential, which demonstrates little variability within the homogenous population
structure and range of size classes (due to overharvesting) found at the Costa Brava. The study of reproductive output is
an important tool for ecosystem management, and this work recommends basing specific exploitation laws for distinctive populations
on colony size, which is found to have a larger effect on reproductive potential than mesoscale variability.
An erratum to this article can be found at 相似文献