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921.
Power matters in closing the phenotyping gap 总被引:1,自引:0,他引:1
Meyer CW Elvert R Scherag A Ehrhardt N Gailus-Durner V Fuchs H Schäfer H Hrabé de Angelis M Heldmaier G Klingenspor M 《Die Naturwissenschaften》2007,94(5):401-406
Much of our understanding of physiology and metabolism is derived from investigating mouse mutants and transgenic mice, and
open-access platforms for standardized mouse phenotyping such as the German Mouse Clinic (GMC) are currently viewed as one
powerful tool for identifying novel gene-function relationships. Phenotyping or phenotypic screening involves the comparison of wild-type control mice with their mutant or transgenic littermates. In our study, we explored
the extent to which standardized phenotyping will succeed in detecting biologically relevant phenotypic differences in mice
generated and provided by different collaborators. We analyzed quantitative metabolic data (body mass, energy intake, and
energy metabolized) collected at the GMC under the current workflow, and used them for statistical power considerations. Our
results demonstrate that there is substantial variability in these parameters among lines of wild-type C57BL/6 (B6) mice from
different sources. Given this variable background noise in mice that serve as controls, subtle phenotypes in mutant or transgenic
littermates may be overlooked. Furthermore, a phenotype observed in one cohort of a mutant line may not be reproducible (to
the same extent) in mice coming from a different environment or supplier. In the light of these constraints, we encourage
researchers to incorporate information on intrastrain variability into future study planning, or to perform advanced hierarchical
analyses. Both will ultimately improve the detectability of novel phenotypes by phenotypic screening.
Carola W. Meyer and Ralf Elvert contributed equally to this work. 相似文献
922.
923.
The continuing conundrum of the LEA proteins 总被引:9,自引:0,他引:9
Research into late embryogenesis abundant (LEA) proteins has been ongoing for more than 20 years but, although there is a strong association of LEA proteins with abiotic stress tolerance particularly dehydration and cold stress, for most of that time, their function has been entirely obscure. After their initial discovery in plant seeds, three major groups (numbered 1, 2 and 3) of LEA proteins have been described in a range of different plants and plant tissues. Homologues of groups 1 and 3 proteins have also been found in bacteria and in certain invertebrates. In this review, we present some new data, survey the biochemistry, biophysics and bioinformatics of the LEA proteins and highlight several possible functions. These include roles as antioxidants and as membrane and protein stabilisers during water stress, either by direct interaction or by acting as molecular shields. Along with other hydrophilic proteins and compatible solutes, LEA proteins might also serve as “space fillers” to prevent cellular collapse at low water activities. This multifunctional capacity of the LEA proteins is probably attributable in part to their structural plasticity, as they are largely lacking in secondary structure in the fully hydrated state, but can become more folded during water stress and/or through association with membrane surfaces. The challenge now facing researchers investigating these enigmatic proteins is to make sense of the various in vitro defined functions in the living cell: Are the LEA proteins truly multi-talented, or are they still just misunderstood? 相似文献
924.
PROBLEM: The purpose of this study was to examine the relationship between overall risk of injury and time use patterns between work and active recreation among adolescents and young adults. METHODS: Using a representative sample of 9,795 Canadians aged 15-24 years, a multivariate logistic regression on the likelihood of any medically attended injury was conducted, including sociodemographic, individual, and time factors. RESULTS: Young people who engaged in a combination of high work and high activity hours were twice as likely to sustain a medically attended injury compared to those who worked low hours, but did not participate in any recreational activity. Those respondents who were not in school had a 43% increase in injury risk compared to full-time students. SUMMARY: Our findings suggest that injury risk was not a simple function of fatigue and cumulative exposure time. Our findings suggest the importance of considering time use and the associated injury risk tradeoffs. IMPACT ON INDUSTRY: Relevant to state and federal work safety policy makers, our findings suggest the importance of understanding where youth might otherwise spend their time if constraint were placed on their employment opportunities, and the associated injury risk tradeoffs must be taken into consideration. 相似文献
925.
The existence of sex is one of the major unsolved problems in biology. We use computer simulations to model conditions in
which sex may first become established. We develop an individual-based population model and show that a hypothetical facultative
sex gene can fix, provided that the initial cost is low. It is demonstrated that the equilibrium fitness in the population
increases with increasing population size and decreasing mutation rate. The probability of the establishment of the sex gene
is found not to be directly related to the fitness difference between the asexual and sexual populations. This change in fitness
on changing the parameters of the model is investigated. 相似文献
926.
The neonatal incidence rate of Down syndrome (DS) is well-known to accelerate strongly with maternal age. This non-linearity
renders mere accumulation of defects at recombination during prolonged first meiotic prophase implausible as an explanation
for DS rate increase with maternal age, but might be anticipated from chromosomal drive (CD) for trisomy 21. Alternatively,
as there is selection against genetically disadvantaged embryos, the screening system that eliminates embryos with trisomy
21 might decay with maternal age. In this paper, we provide the first evidence for relaxed filtering stringency (RFS) to represent
an adaptive maternal response that could explain accelerating DS rates with maternal age. Using historical data, we show that
the proportion of aberrant live births decrease with increased family size in older mothers, that inter-birth intervals are
longer before affected neonates than before normal ones, and that primiparae exhibit elevated levels of DS incidence at higher
age. These findings are predicted by adaptive RFS but cannot be explained by the currently available alternative non-adaptive
hypotheses, including CD. The identification of the relaxation control mechanism and therapeutic restoration of a stringent
screen may have considerable medical implications. 相似文献
927.
INTRODUCTION: This study evaluated the implementation of a second phase training program for novice drivers in Spain, which puts the primary focus of the training on the higher hierarchical levels of driver behavior. METHOD: Two hundred and sixty-three participants took part throughout the study, which was implemented as an experimental design with the test and control groups assessed before and after the one day safety training. Measurement of the impact of the training program focused on the participants' self-evaluation and self-reporting of some driving behavior indicators related to accident risk. RESULTS: Data analysis showed a change in the expected direction in the scale related to the skills for careful driving, but not for the other four scales considered. A feedback survey about the training course offered some important input for evaluating the organization, contents, tuition, and results of the three parts of the training program (discussion group, on-road and track training) as reported by the participants in the test group. CONCLUSIONS AND SUGGESTIONS: The results of the experiment show that using a one day driver safety course, it is possible to change some of the drivers' evaluations connected to safe driving style into safe direction. The follow-up period was exceptionally long (9 months) and the design (randomly divided experimental and control groups with before and after measurements) was reliable. More effort should be devoted to improving the on-road part of the training, which was often perceived as a typical driving lesson rather than a feedback drive. IMPACT ON INDUSTRY: The findings suggest consideration of a mandatory 2nd phase driver training programme as a means to raise awareness of the full range of risks encountered by novice drivers, and as already introduced in 5 EU countries: Austria, Estonia, Finland, Luxembourg and Switzerland. 相似文献
928.
Motor vehicle crashes killed almost 5,000 pedestrians in 2005 in the United States. Pedestrian risk may be higher in areas characterized by urban sprawl. From 2000 to 2004, pedestrian fatality rates declined in the United States, but the Atlanta metropolitan statistical area did not experience the same decline. Pedestrian fatality rates for males, Hispanics, and the 15–34 and 35–54 year age groups were higher in Atlanta than in the United States overall. Pedestrian safety interventions should be targeted to high-risk populations and localized pedestrian settings. 相似文献
929.
The double trade-off between adaptation and mitigation for sea level rise: an application of FUND 总被引:6,自引:2,他引:4
Richard S. J. Tol 《Mitigation and Adaptation Strategies for Global Change》2007,12(5):741-753
This paper studies the effects of adaptation and mitigation on the impacts of sea level rise. Without adaptation, the impact
of sea level rise would be substantial, almost wiping out entire countries by 2100, although the globally aggregate effect
is much smaller. Adaptation would reduce potential impacts by a factor 10–100. Adaptation would come at a minor cost compared
to the damage avoided. As adaptation depends on socio-economic status, the rank order of most vulnerable countries is different
than the rank order of most exposed countries. Because the momentum of sea level rise is so large, mitigation can reduce impacts
only to a limited extent. Stabilising carbon dioxide concentrations at 550 ppm would cut impacts in 2100 by about 10%. However,
the costs of emission reduction lower the avoided impacts by up to 25% (average 10%). This is partly due to the reduced availability
of resources for adaptation, and partly due to the increased sensitivity to wetland loss by adaptation.
相似文献
Richard S. J. TolEmail: |
930.
Helen Sheridan Barry J. McMahonTim Carnus John A. FinnAnnette Anderson Alvin J. HeldenAnne Kinsella Gordon Purvis 《Agriculture, ecosystems & environment》2011,144(1):130-135
In this study, habitat surveys were undertaken on 50 grass-based farms in SE Ireland and data digitised onto aerial photography. Additional data i.e. stocking rates, and participation (or otherwise) in the Irish Rural Environment Protection Scheme (REPS) were collected and analysed as possible explanatory variables for farm habitat composition.Results indicated that approximately 14.3% of the land area of sampled farms comprised of semi-natural habitat types, a proportion substantially greater than has been reported for many other European countries. The most frequently recorded semi-natural habitats included, field boundaries, scrub, and deciduous and riparian woodlands.Multivariate analysis of farm habitat configuration showed a strong dichotomy between dairy and non-dairy farming systems. Habitats such as intensively managed grassland and built ground were closely associated with dairy-based enterprises. In contrast, the incidence of other habitat types was associated with non-dairy and/or REPS participating enterprises. The ecological quality of field boundaries as assessed by the Field Boundary Evaluation and Grading System (FBEGS) Index was significantly greater on dairy, compared with dry-stock farms.This dichotomy in farm habitat composition is not reflected within current Agri-Environment (AE) policy. Integration of locally important drivers of habitat diversity into the design and implementation of AE policy, is integral to the successful performance of AE schemes. 相似文献