全文获取类型
收费全文 | 139篇 |
免费 | 22篇 |
国内免费 | 7篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 12篇 |
2012年 | 12篇 |
2011年 | 11篇 |
2010年 | 1篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有168条查询结果,搜索用时 15 毫秒
41.
42.
原发性腹膜后节细胞神经纤维瘤在临床上是属于极少见的病例,通常患者就诊时无明显临床症状。本文报道1例43岁成年男性的腹膜后节细胞神经纤维瘤并进行相关文献的复习。已有研究证实影像学检查可对原发性腹膜后肿瘤的良恶性鉴别提供重要依据,节细胞神经纤维瘤的影像学检查亦具有其特征性表现,但最终本病的确诊仍依赖病理及免疫组化技术。影像学检查是确定原发性腹膜后肿瘤的治疗计划的必要措施。目前手术已成为治疗腹膜后节细胞神经纤维瘤的首选治疗。辅以血管外科技术,肿瘤的根治性切除已在临床上广泛开展。通过手术治疗后尽管有二次复发可能,但腹膜后节细胞神经瘤预后仍较好。 相似文献
43.
This study formulates a model to maximize the profit of a lignocellulosic biofuel supply chain ranging from feedstock suppliers to biofuel customers. The model deals with a time-staged, multi-commodity, production/distribution system, prescribing facility locations and capacities, technologies, and material flows. A case study based on a region in Central Texas demonstrates application of the proposed model to design the most profitable biofuel supply chain under each of several scenarios. A sensitivity analysis identifies that ethanol (ETOH) price is the most significant factor in the economic viability of a lignocellulosic biofuel supply chain. 相似文献
44.
This paper presents qualitative and quantitative study of a TB mathematical model to test results from a survey carried out in Benin City, Nigeria. The purpose of the survey was to determine factors that could enhance the case detection rate of tuberculosis. Results from the survey identified four key factors that must be combined for an effective control of TB and increase the case detection rate: effective awareness programme, active cough identification, associated cost factor for treatment of identified cases and effective treatment. The overall effect of these factors on the basic reproduction number under treatment, RT, of the TB model was considered. In all, a serious concentration on tuberculosis awareness programmes and active cough identification as a marker for someone having TB was shown to significantly reduce the value of the reproduction number, hereby reducing the severity of the disease in the presence of treatment. 相似文献
45.
Basil Sansom 《Anthropological Forum》2007,17(1):71-92
Australia's Native Title Act 1993 (Cth) allows Indigenous Australians to lay claims to traditional country located on unalienated Crown land. The Act also admits claims to compensation for the loss of traditional country that has been appropriated and made subject to freehold or other forms of tenure. The Yulara case discussed here was historically important. It was the first case mounted to determine appropriate compensation for the extinguishment of native title. In a compensation claim, the Indigenous applicants must first establish that (taken together) they are both (i) the rightful heirs to ancestral holders of native title and (ii) that they still maintain the traditions and customs of their forebears (phase 1). Once their holding of native title has been established at law, the applicants may then enter their claim to monetary compensation for the ‘extinguishment’ of their native title over designated lands (phase 2). In the Yulara case, it was found that the applicants were not constituted as a group of recognisable native title holders whose rights to country were rooted in those traditional laws and customs that obtained when the Yulara lands were officially brought under the dominion of British authorities ‘at sovereignty’ (1824). The case could not, therefore, proceed to a hearing of the compensation phase. Eight issues concerning the proper performance of the anthropologist as expert witness in native title matters were raised by the trial judge in the Yulara case. This paper deals with the bearing of the judge's observations on those anthropological representations that may be made in future native title cases. 相似文献
46.
Most methods for genome-wide association studies (GWAS) focus on discovering a single genetic variant, but the pathogenesis of complex diseases is thought to arise from the joint effect of multiple genetic variants. Information about pathway structure, such as the interactions and distances between gene products within pathways, can help us learn more about the functions and joint effect of genes associated with disease risk. We developed a novel sub-pathway based approach to study the joint effect of multiple genetic variants that are modestly associated with disease. The approach prioritized sub-pathways based on the significance values of single nucleotide polymorphisms (SNPs) and the interactions and distances between gene products within pathways. We applied the method to seven complex diseases. The result showed that our method can efficiently identify statistically significant sub-pathways associated with the pathogenesis of complex diseases. The approach identified sub-pathways that may inform the interpretation of GWAS data. 相似文献
47.
Summary Identification of novel biomarkers for risk assessment is important for both effective disease prevention and optimal treatment recommendation. Discovery relies on the precious yet limited resource of stored biological samples from large prospective cohort studies. Case‐cohort sampling design provides a cost‐effective tool in the context of biomarker evaluation, especially when the clinical condition of interest is rare. Existing statistical methods focus on making efficient inference on relative hazard parameters from the Cox regression model. Drawing on recent theoretical development on the weighted likelihood for semiparametric models under two‐phase studies ( Breslow and Wellner, 2007 ), we propose statistical methods to evaluate accuracy and predictiveness of a risk prediction biomarker, with censored time‐to‐event outcome under stratified case‐cohort sampling. We consider nonparametric methods and a semiparametric method. We derive large sample properties of proposed estimators and evaluate their finite sample performance using numerical studies. We illustrate new procedures using data from Framingham Offspring Study to evaluate the accuracy of a recently developed risk score incorporating biomarker information for predicting cardiovascular disease. 相似文献
48.
Gayathri Babarenda Gamage Carol Boyle Sarah J. McLaren Jake McLaren 《The International Journal of Life Cycle Assessment》2008,13(5):401-411
Background, aims and scope The environmental aspects of companies and their products are becoming more significant in delivering competitive advantage.
Formway Furniture, a designer and manufacturer of office furniture products, is a New Zealand-based company that is committed
to sustainable development. It manufactures two models of the light, intuitive, flexible and environmental (LIFE) office chair:
one with an aluminium base and one with a glass-filled nylon (GFN) base. It was decided to undertake a life cycle assessment
(LCA) study of these two models in order to: (1) determine environmental hotspots in the life cycle of the two chairs (goal
1); (2) compare the life cycle impacts of the two chairs (goal 2); and (3) compare alternative potential waste-management
scenarios (goal 3). The study also included sensitivity analysis with respect to recycled content of aluminium in the product.
Materials and methods The LIFE chair models consist of a mix of metal and plastic components manufactured by selected Formway suppliers according
to design criteria. Hence, the research methodology included determining the specific material composition of the two chair
models and acquisition of manufacturing data from individual suppliers. These data were compiled and used in conjunction with
pre-existing data, specifically from the ecoinvent database purchased in conjunction with the SimaPro7 LCA software, to develop
the life cycle inventory of the two chair models. The life cycle stages included in the study extended from raw-material extraction
through to waste management. Impact assessment was carried out using CML 2 baseline 2000, the methodology developed by Leiden
University’s Institute for Environmental Sciences.
Results This paper presents results for global warming potential (GWP100). The study showed a significant impact contribution from
the raw-material extraction/refinement stage for both chair models; aluminium extraction and refining made the greatest contribution
to GWP100. The comparison of the two LIFE chair models showed that the model with the aluminium base had a higher GWP100 impact
than the model with the GFN base. The waste-management scenario compared the GWP100 result when (1) both chair models were
sent to landfill and (2) steel and aluminium components were recycled with the remainder of the chair sent to landfill. The
results showed that the recycling scenario contributed to a reduced GWP100 result. Since production and processing of aluminium
was found to be significant, a sensitivity analysis was carried out to determine the impact of using aluminium with different
recycled contents (0%, 34% and 100%) in both waste-management scenarios; this showed that increased use of recycled aluminium
was beneficial. The recycling at end-of-life scenarios was modelled using two different end-of-life allocation approaches,
i.e. consequential and attributional, in order to illustrate the variation in results caused by choice of allocation approach.
The results using the consequential approach showed that recycling at end-of-life was beneficial, while use of the attributional
method led to a similar GWP100 as that seen for the landfill scenario.
Discussion The results show that the main hotspot in the life cycle is the raw-material extraction/refinement stage. This can be attributed
to the extraction and processing of aluminium, a material that is energy intensive. The LIFE chair model with the aluminium
base has a higher GWP100 as it contains more aluminium. Sensitivity analysis pertaining to the recycled content of aluminium
showed that use of aluminium with high recycled content was beneficial; this is because production of recycled aluminium is
less energy intensive than production of primary aluminium. The waste-management scenario showed that recycling at end-of-life
resulted in a significantly lower GWP100 than landfilling at end-of-life. However, this result is dependent upon the modelling
approach used for recycling.
Conclusions With respect to goal 1, the study found that the raw-material extraction/refinement stage of the life cycle was a significant
factor for both LIFE chair models. This was largely due to the use of aluminium in the product. For goal 2, it was found that
the LIFE chair model with the aluminium base had a higher GWP100 than the GFN model, again due to the material content of
the two models. Results for goal 3 illustrated that recycling at end-of-life is beneficial when using a system expansion (consequential)
approach to model recycling; if an attributional ‘cut-off’ approach is used to model recycling at end-of-life, there is virtually
no difference in the results between landfilling and recycling. Sensitivity analysis pertaining to the recycled content of
aluminium showed that use of higher recycled contents leads to a lower GWP100 impact.
Recommendation and perspectives Most of the GWP100 impact was contributed during the raw-material extraction/refinement stage of the life cycle; thus, the
overall impact of both LIFE chair models may be reduced through engaging in material choice and supply chain environmental
management with respect to environmental requirements. The study identified aluminium components as a major contributor to
GWP100 for both LIFE chair models and also highlighted the sensitivity of the results to its recycled content. Thus, it is
recommended that the use of aluminium in future product designs be limited unless it is possible to use aluminium with a high
recycled content. With respect to waste management, it was found that a substantial reduction in the GWP100 impact would occur
if the chairs are recycled rather than landfilled, assuming an expanding market for aluminium. Thus, recycling the two LIFE
chair models at end-of-life is highly recommended. 相似文献
49.
A precise definition of case fatality proportion for compartmental disease transmission models with disease induced mortality
rate is given. This is applied in classical epidemic modeling frameworks to models with multiple infectious stages, with multi-groups,
with spatial patches, and with age of infection. It is shown that the case fatality proportion is the sum over all stages
of the product of the probability of dying from the disease at a given stage and the probability of surviving to that stage.
The derived expressions for case fatality can be used to estimate the disease induced death rates from more readily available
data. 相似文献
50.