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1.
Diane Hope Weixing Zhu Corinna Gries Jacob Oleson Jason Kaye Nancy B. Grimm Lawrence A. Baker 《Urban Ecosystems》2005,8(3-4):251-273
We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding
desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well
as for the desert and urban sites separately. Concentrations of both NO3-N and NH4-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO3-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious
surfaces and lawn, whereas soil NH4-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO3-N and NH4-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation
of soil NO3-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic
soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than
factors related to an urban-rural gradient. 相似文献
2.
We consider assortment problems under a mixture of multinomial logit models. There is a fixed revenue associated with each product. There are multiple customer types. Customers of different types choose according to different multinomial logit models whose parameters depend on the type of the customer. The goal is to find a set of products to offer so as to maximize the expected revenue obtained over all customer types. This assortment problem under the multinomial logit model with multiple customer types is NP‐complete. Although there are heuristics to find good assortments, it is difficult to verify the optimality gap of the heuristics. In this study, motivated by the difficulty of finding optimal solutions and verifying the optimality gap of heuristics, we develop an approach to construct an upper bound on the optimal expected revenue. Our approach can quickly provide upper bounds and these upper bounds can be quite tight. In our computational experiments, over a large set of randomly generated problem instances, the upper bounds provided by our approach deviate from the optimal expected revenues by 0.15% on average and by less than one percent in the worst case. By using our upper bounds, we are able to verify the optimality gaps of a greedy heuristic accurately, even when optimal solutions are not available. 相似文献
3.
Caitlin Ward Jacob Oleson J. Bruce Tomblin Elizabeth Walker 《Journal of applied statistics》2022,49(2):449
Psychometric growth curve modeling techniques are used to describe a person’s latent ability and how that ability changes over time based on a specific measurement instrument. However, the same instrument cannot always be used over a period of time to measure that latent ability. This is often the case when measuring traits longitudinally in children. Reasons may be that over time some measurement tools that were difficult for young children become too easy as they age resulting in floor effects or ceiling effects or both. We propose a Bayesian hierarchical model for such a scenario. Within the Bayesian model we combine information from multiple instruments used at different age ranges and having different scoring schemes to examine growth in latent ability over time. The model includes between-subject variance and within-subject variance and does not require linking item specific difficulty between the measurement tools. The model’s utility is demonstrated on a study of language ability in children from ages one to ten who are hard of hearing where measurement tool specific growth and subject-specific growth are shown in addition to a group level latent growth curve comparing the hard of hearing children to children with normal hearing.KEYWORDS: Bayesian hierarchical models, psychometric modeling, language ability, growth curve modeling, longitudinal analysis 相似文献
4.
Negative (But Not Positive) Parenting Interacts with Infant Negative Affect to Predict Infant Approach: Evidence of Diathesis‐Stress 下载免费PDF全文
Jacob B. Holzman Nicole M. Burt Erin S. Edwards Leanna D. Rosinski David J. Bridgett 《Infancy》2018,23(3):471-480
Temperament by parenting interactions may reflect that individuals with greater risk are more likely to experience negative outcomes in adverse contexts (diathesis‐stress) or that these individuals are more susceptible to contextual influences in a “for better or for worse” pattern (differential susceptibility). Although such interactions have been identified for a variety of child outcomes, prior research has not examined approach characteristics—excitement and approach toward pleasurable activities—in the first year of life. Therefore, this study investigated whether 6‐month maternal reported infant negative affect—a phenotypic marker of risk/susceptibility—interacted with 8‐month observed parenting behaviors (positive parenting, negative parenting) to predict 12‐month infant behavioral approach. Based on a sample of mothers and their infants (N = 150), results indicated that negative parenting was inversely associated with subsequent approach for infants with high, but not low, levels of negative affect. Similar results did not occur regarding positive parenting. These findings better fit a diathesis‐stress model rather than a differential susceptibility model. Implications and limitations of these findings are discussed. 相似文献
5.
Although subprime mortgage lending and unemployment were largely responsible for the wave of foreclosures during the Great Recession, additional sources of financial risk may have exacerbated the crisis. We hypothesize that many parents sending children to college were financially overextended and vulnerable to foreclosure as the economy contracted. With commuting zone panel data from 2006 to 2011, we show that increasing rates of college attendance across the income distribution in one year predict a foreclosure rate increase in subsequent years, net of fixed characteristics and changes in employment, refinance debt, house prices, and 19-year-old population size. We find similar evidence of college-related foreclosure risk using longitudinal household data from the Panel Study of Income Dynamics. Our findings uncover a previously overlooked dimension of the foreclosure crisis, and highlight mortgage insecurity as an inadvertent consequence of parental investment in higher education. 相似文献
6.
Do the Constructs of the FACES IV Change Based on Definitions of “Family?” A Measurement Invariance Test 下载免费PDF全文
Jacob B. Priest Elizabeth O. Parker Sarah B. Woods 《Journal of marital and family therapy》2018,44(2):336-352
The Family Adaptability and Cohesion Scale (FACES) IV does not provide instructions about which family members respondents should think about while answering questions. This study examined which family members respondents thought about while completing the FACES IV, and if this changed measurement invariance and population heterogeneity of the measure. Using a sample of n = 511 individuals, a latent class analysis showed three distinct classes: Nuclear Family, Family of Origin, and All of the Above. The FACES IV demonstrated measurement invariance across classes on the majority of subscales; however, population heterogeneity tests suggested that the means and variances of the subscales varied across classes. The findings suggest further examination of how the measure functions with unique family constellations is warranted. 相似文献
7.
Jacob Mwathi Mati 《Voluntas: International Journal of Voluntary and Nonprofit Organizations》2012,23(1):63-84
This article analyses the Ufungamano Initiative, a broad-based movement involved in constitutional reform struggles in Kenya.
By analysing the rise, operations, achievements, and challenges of the Initiative, I argue that contemporary constitutional
reform struggles in Kenya were societal responses to an avaricious political and economic class. It is further argued that
the movement resulted from a fragmented elite consensus that widened political opportunities for contentious politics and
therefore forced concessions for popular engagement in re-defining the relationship between the people and the political class.
Ultimately, the Ufungamano Initiative’s power eroded as a result of multiple competing parochial interests in the movement. 相似文献
8.
9.
We present a study of the relationship between gender, linguistic style, and social networks, using a novel corpus of 14,000 Twitter users. Prior quantitative work on gender often treats this social variable as a female/male binary; we argue for a more nuanced approach. By clustering Twitter users, we find a natural decomposition of the dataset into various styles and topical interests. Many clusters have strong gender orientations, but their use of linguistic resources sometimes directly conflicts with the population‐level language statistics. We view these clusters as a more accurate reflection of the multifaceted nature of gendered language styles. Previous corpus‐based work has also had little to say about individuals whose linguistic styles defy population‐level gender patterns. To identify such individuals, we train a statistical classifier, and measure the classifier confidence for each individual in the dataset. Examining individuals whose language does not match the classifier's model for their gender, we find that they have social networks that include significantly fewer same‐gender social connections and that, in general, social network homophily is correlated with the use of same‐gender language markers. Pairing computational methods and social theory thus offers a new perspective on how gender emerges as individuals position themselves relative to audiences, topics, and mainstream gender norms. 相似文献
10.
We use duration models on a well-known historical data set of more than 15,000 families and 60,000 births in England for the period 1540–1850 to show that the sampled families adjusted the timing of their births in accordance with the economic conditions as well as their stock of dependent children. The effects were larger among the lower socioeconomic ranks. Our findings on the existence of parity-dependent as well as parity-independent birth spacing in England are consistent with the growing evidence that marital birth control was present in pre-transitional populations. 相似文献