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51.
Poverty among inner‐city residents is associated with their marginal status in the labor market. Marginalization in the labor market begins during youth when important educational and employment decisions are made. Analysis of 1990 U.S. Census tract data for San Antonio, Texas identifies the lack of a high school diploma, poverty, non‐employment, and non‐enrollment in school as conditions of marginality for youth. Spatial patterns of youth labor market marginalization show concentrations in the inner city and in sectors on the West, South, and Eastside. Regression analysis reveals that levels of youth marginalization are associated with neighborhood context represented by the employment, behavioral, and ethnic characteristics of the overall residential population of a census tract. 相似文献
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53.
Nicholas A. Cradock-Henry Bob Frame Benjamin L. Preston Andy Reisinger Dale S. Rothman 《Climatic change》2018,150(3-4):333-341
The parallel scenario process enables characterization of climate-related risks and response options to climate change under different socio-economic futures and development prospects. The process is based on representative concentration pathways, shared socio-economic pathways, and shared policy assumptions. Although this scenario architecture is a powerful tool for evaluating the intersection of climate and society at the regional and global level, more specific context is needed to explore and understand risks, drivers, and enablers of change at the national and local level. We discuss the need for a stronger recognition of such national-scale characteristics to make climate change scenarios more relevant at the national and local scale, and propose ways to enrich the scenario architecture with locally relevant details that enhance salience, legitimacy, and credibility for stakeholders. Dynamic adaptive pathways are introduced as useful tools to draw out which elements of a potentially infinite scenario space connect with decision-relevant aspects of particular climate-related and non-climate-related risks and response options. Reviewing adaptation pathways for New Zealand case studies, we demonstrate how this approach could bring the global-scale scenario architecture within reach of local-scale decision-making. Such a process would enhance the utility of scenarios for mapping climate-related risks and adaptation options at the local scale, involving appropriate stakeholder involvement. 相似文献
54.
Cultural political economy: On making the cultural turn without falling into soft economic sociology 总被引:1,自引:0,他引:1
This article explores the implications of making the cultural turn in the engagement of economic and political geography with issues of political economy. It seeks to steer a path between a fetishistic, reified economics that naturalizes economic categories and a soft economic sociology that focuses on the similarities between economic and other socio-cultural activities at the expense of the specificity of the economic. We show how combining critical semiotic analysis with an evolutionary and institutional approach to political economy offers one interesting way to achieve this goal. An evolutionary and institutional approach to semiosis enables us to recognize the semiotic dimensions of political economy at the same time as establishing how and why only some economic imaginaries among the many that circulate actually come to be selected and institutionalized; and Marxian political economy enables us to identify the contradictions and conflicts that make capital accumulation inherently improbable and crisis-prone, creating the space for economic imaginaries to play a role in stabilizing accumulation in specific spatio-temporal fixes and/or pointing the way forward from recurrent crises. The paper illustrates these arguments with a case study on the Flemish ‘anchoring strategy’ as a specific regional economic development strategy. It concludes with a set of guidelines for the further development of cultural political economy. 相似文献
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56.
The problem of fitting a probability distribution, here log-Pearson Type III distribution, to extreme floods is considered from the point of view of two numerical and three non-numerical criteria. The six techniques of fitting considered include classical techniques (maximum likelihood, moments of logarithms of flows) and new methods such as mixed moments and the generalized method of moments developed by two of the co-authors. The latter method consists of fitting the distribution using moments of different order, in particular the SAM method (Sundry Averages Method) uses the moments of order 0 (geometric mean), 1 (arithmetic mean), –1 (harmonic mean) and leads to a smaller variance of the parameters. The criteria used to select the method of parameter estimation are:
These criteria are transformed into value functions or fuzzy set membership functions and then three Multiple Criteria Decision Modelling (MCDM) techniques, namely, composite programming, ELECTRE, and MCQA, are applied to rank the estimation techniques. 相似文献
| - the two statistical criteria of mean square error and bias; |
| - the two computational criteria of program availability and ease of use; |
| - the user-related criterion of acceptability. |
57.
Behrouz Ahmadi‐Nedushan André St‐Hilaire Taha B. M. J. Ouarda Laurent Bilodeau Élaine Robichaud Nathalie Thiémonge Bernard Bobée 《水文研究》2007,21(1):21-34
Successful applications of stochastic models for simulating and predicting daily stream temperature have been reported in the literature. These stochastic models have been generally tested on small rivers and have used only air temperature as an exogenous variable. This study investigates the stochastic modelling of daily mean stream water temperatures on the Moisie River, a relatively large unregulated river located in Québec, Canada. The objective of the study is to compare different stochastic approaches previously used on small streams to relate mean daily water temperatures to air temperatures and streamflow indices. Various stochastic approaches are used to model the water temperature residuals, representing short‐term variations, which were obtained by subtracting the seasonal components from water temperature time‐series. The first three models, a multiple regression, a second‐order autoregressive model, and a Box and Jenkins model, used only lagged air temperature residuals as exogenous variables. The root‐mean‐square error (RMSE) for these models varied between 0·53 and 1·70 °C and the second‐order autoregressive model provided the best results. A statistical methodology using best subsets regression is proposed to model the combined effect of discharge and air temperature on stream temperatures. Various streamflow indices were considered as additional independent variables, and models with different number of variables were tested. The results indicated that the best model included relative change in flow as the most important streamflow index. The RMSE for this model was of the order of 0·51 °C, which shows a small improvement over the first three models that did not include streamflow indices. The ridge regression was applied to this model to alleviate the potential statistical inadequacies associated with multicollinearity. The amplitude and sign of the ridge regression coefficients seem to be more in agreement with prior expectations (e.g. positive correlation between water temperature residuals of different lags) and make more physical sense. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
58.
岩浆绿帘石能够作为压力计反映岩体侵位深度,进而可估算地壳抬升剥蚀速率及地壳演化历史,因而引起了人们的研究关注。在长乐—南澳构造带泉港临头地段发现了片麻状英云闪长岩中的岩浆绿帘石。该地段是我国当前报道岩浆绿帘石的第5处产出地,但在东南沿海地区尚属首次发现。含岩浆绿帘石的片麻状英云闪长岩形成于早白垩世(K1),以钙性(C,Peacock碱钙指数)、中钾钙碱性系列(MKCA)、准铝质和弱过铝质、钙碱性系列(CA,Miyashiro SiO2-FeO*/MgO)为主,具镁安山岩系列(MA)性质,呈奥长花岗岩演化趋势(Tdj);轻稀土(LREE)较富集,铕负异常不明显;微量元素呈现较大的钽(Ta)、磷(P)和钛(Ti)负异常,显示出造山带火山弧花岗岩的特征。片麻状英云闪长岩中绿帘石岩相学特征显示,黑云母和自形的绿帘石分布于斜长石的隙间,为典型的填间结构;绿帘石与黑云母相互接触、相互包裹,是一起从富水的晚期岩浆中结晶出来的原生矿物,不是交代斜长石的岩浆期后的次生矿物。绿帘石电子探针分析结果显示Ps值为24~29,TiO2含量均小于0.1%。综合绿帘石岩相学与化学特征知悉,泉港临头片麻状英云闪长岩中的绿帘石为岩浆绿帘石。岩浆绿帘石形成压力约870 MPa,深度为25~32 km,而现今东南沿海陆壳厚度约30 km,据此推测,早白垩世(K1)时东南沿海陆壳厚度为55~62 km;早白垩世(K1)之后,地壳可能经历了多次抬升。 相似文献
59.
In order to better model the fate and transport of material in a combined sewer overflow (CSO), hydrologic and geochemical measurements were made during a storm event in Flushing Bay, NY, USA. Particle size, total suspended solids concentrations, and CSO solid density are used to calculate the settling velocity of aggregates of the CSO material. Roughly half of the material that is discharged from the outfall sinks rapidly to the bottom, while the other half forms a turbid surface plume in fresher water. The dry solid density of the CSO material was 1589 kg m(-3) and the volume fraction of solid material to total aggregate volume ranged from 0.1 to 1.0. The settling velocity estimates of aggregated material in the surface plume ranged from about 0.5 to 9.0 mm s(-1) with a median settling velocity of 2.9 mm s(-1). A strong inverse relationship between the size of the aggregates and the aggregate density resulted in a fractal dimension of the aggregates of 2.3. 相似文献
60.
鄂尔多斯盆地南部延长组富铀凝灰岩地球化学特征及形成机制 总被引:1,自引:0,他引:1
本文系统地研究了鄂尔多斯盆地南部延长组凝灰岩元素和同位素地球化学特征。结果表明:凝灰岩主量元素具有高K、高Al、Si中等至高、低Na的特征;REE总体特征为轻稀土富集、重稀土亏损,∑REE在48.57~402.12μg/g之间变化,Eu呈现出负异常,在0.34~0.82内变化,δCe范围在0.80~2.08之间;微量元素中U含量在3.12~144μg/g之间,Ba、U、Th、Hf和Ce呈明显正异常,Nb、P、Ti和Rb呈现负异常。详细的分析表明:U的富集和一些微量元素如Ta、Dy、Lu等相关,Th与∑REE存在明显的正相关性,这些变化可能和盆地中铀矿的富集有关;凝灰岩的硫同位素总体呈现深源特征。根据以上的研究对凝灰岩的形成原因及形成环境进行了探讨。鄂尔多斯盆地南部延长组凝灰岩来源于秦岭造山带火山作用,其中的铀元素富集是由于砂岩型铀矿中铀向凝灰岩迁移而被还原所致。本研究对盆地砂岩型铀矿的铀运移和富集机理认识具有一定指导意义。 相似文献