首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5214篇
  免费   165篇
  国内免费   54篇
管理学   400篇
民族学   11篇
人才学   6篇
人口学   26篇
丛书文集   357篇
理论方法论   59篇
综合类   3121篇
社会学   218篇
统计学   1235篇
  2024年   8篇
  2023年   45篇
  2022年   17篇
  2021年   59篇
  2020年   70篇
  2019年   85篇
  2018年   122篇
  2017年   170篇
  2016年   104篇
  2015年   152篇
  2014年   246篇
  2013年   661篇
  2012年   329篇
  2011年   366篇
  2010年   284篇
  2009年   303篇
  2008年   311篇
  2007年   322篇
  2006年   291篇
  2005年   285篇
  2004年   215篇
  2003年   221篇
  2002年   199篇
  2001年   161篇
  2000年   106篇
  1999年   52篇
  1998年   35篇
  1997年   33篇
  1996年   22篇
  1995年   14篇
  1994年   20篇
  1993年   12篇
  1992年   15篇
  1991年   10篇
  1990年   8篇
  1989年   9篇
  1988年   5篇
  1987年   10篇
  1986年   3篇
  1985年   15篇
  1984年   15篇
  1983年   7篇
  1982年   8篇
  1980年   2篇
  1979年   2篇
  1977年   4篇
排序方式: 共有5433条查询结果,搜索用时 15 毫秒
171.
172.
河北省作为京津冀协同发展及其雄安新区建设的重要一环,具有很强文化资源禀赋。通过对河北省传统文化近期偏好、现代阐释和愿景设计的研究,为河北省消除地区文化差异和经济差异提供理论指导,并为之注入现代内涵,具有很强的现实意义和理论意义。  相似文献   
173.
Smart manufacturing systems (SMSs) are envisioned to contain highly automated and IT-driven production systems. To address the complexity that arises in such systems, a standard and holistic model for describing its activities and their interrelationships is needed. This paper introduces a factory design and improvement (FDI) activity model and illustrates a case study of FDI in an electromechanical component factory. In essence, FDI is a reference activity model that encompasses a range of manufacturing system activities for designing and improving a factory during its initial development and also its operational phases. The FDI model shows not only the dependency between activities and manufacturing control levels but also the pieces of information and software functions each activity relies on. We envision that the availability of these pieces of information in digital form to integrate across the software functions will increase the agility of factory design and improvement projects. Therefore, our future work lies in contributing to standards for exchanging such information.  相似文献   
174.
Abstract

Defining product platform architecture is a critical issue to design and develop product variants. Different factors are highly dependent on the architecture type, such as number of variants, to measure modularity level, component commonality, market demand, etc. It is directly related to manage product portfolios and setting up business plan of a company. Before defining a product platform, whether it is modular or integral product designers need to follow specific design guidelines and checklists. This research mainly focuses on to define the platform architecture as well as provides necessary design guidelines and checklists for the product designers. It also highlights an example product of a case company with the objective to clarify/validate the proposed product design approach. In conclusion, this paper outlines the findings from this research and proposed some critical questions need to be answered within the scope of future research potentials.  相似文献   
175.
从不均等选择概率的角度,提出两类常见的权数调整类型及其调整方法:一是规模调整,使得样本单元权数之和等于总体规模;二是结构调整,使得样本结构和总体结构一致,并构造出加权调整的设计效应模型,应用于复杂样本设计。案例分析显示,加权调整往往导致设计效应变大,带来负的效应,但校准调整能降低设计效应,提高估计精度。  相似文献   
176.
A variety of primary endpoints are used in clinical trials treating patients with severe infectious diseases, and existing guidelines do not provide a consistent recommendation. We propose to study simultaneously two primary endpoints, cure and death, in a comprehensive multistate cure‐death model as starting point for a treatment comparison. This technique enables us to study the temporal dynamic of the patient‐relevant probability to be cured and alive. We describe and compare traditional and innovative methods suitable for a treatment comparison based on this model. Traditional analyses using risk differences focus on one prespecified timepoint only. A restricted logrank‐based test of treatment effect is sensitive to ordered categories of responses and integrates information on duration of response. The pseudo‐value regression provides a direct regression model for examination of treatment effect via difference in transition probabilities. Applied to a topical real data example and simulation scenarios, we demonstrate advantages and limitations and provide an insight into how these methods can handle different kinds of treatment imbalances. The cure‐death model provides a suitable framework to gain a better understanding of how a new treatment influences the time‐dynamic cure and death process. This might help the future planning of randomised clinical trials, sample size calculations, and data analyses.  相似文献   
177.
Several researchers have proposed solutions to control type I error rate in sequential designs. The use of Bayesian sequential design becomes more common; however, these designs are subject to inflation of the type I error rate. We propose a Bayesian sequential design for binary outcome using an alpha‐spending function to control the overall type I error rate. Algorithms are presented for calculating critical values and power for the proposed designs. We also propose a new stopping rule for futility. Sensitivity analysis is implemented for assessing the effects of varying the parameters of the prior distribution and maximum total sample size on critical values. Alpha‐spending functions are compared using power and actual sample size through simulations. Further simulations show that, when total sample size is fixed, the proposed design has greater power than the traditional Bayesian sequential design, which sets equal stopping bounds at all interim analyses. We also find that the proposed design with the new stopping for futility rule results in greater power and can stop earlier with a smaller actual sample size, compared with the traditional stopping rule for futility when all other conditions are held constant. Finally, we apply the proposed method to a real data set and compare the results with traditional designs.  相似文献   
178.
Multiphase experiments are introduced and an overview of their design and analysis as it is currently practised is given via an account of their development since 1955 and a literature survey. Methods that are available for designing and analysing them are outlined, with an emphasis on making explicit the role of the model in their design. The availability of software and its use is described in detail. Overall, while multiphase designs have been applied in areas such as plant breeding, plant pathology, greenhouse experimentation, product storage, gene expression studies, and sensory evaluation, their deployment has been limited.  相似文献   
179.
Fractional factorial (FF) designs are no doubt the most widely used designs in experimental investigations due to their efficient use of experimental runs. One price we pay for using FF designs is, clearly, our inability to obtain estimates of some important effects (main effects or second order interactions) that are separate from estimates of other effects (usually higher order interactions). When the estimate of an effect also includes the influence of one or more other effects the effects are said to be aliased. Folding over an FF design is a method for breaking the links between aliased effects in a design. The question is, how do we define the foldover structure for asymmetric FF designs, whether regular or nonregular? How do we choose the optimal foldover plan? How do we use optimal foldover plans to construct combined designs which have better capability of estimating lower order effects? The main objective of the present paper is to provide answers to these questions. Using the new results in this paper as benchmarks, we can implement a powerful and efficient algorithm for finding optimal foldover plans which can be used to break links between aliased effects.  相似文献   
180.
Patient heterogeneity may complicate dose‐finding in phase 1 clinical trials if the dose‐toxicity curves differ between subgroups. Conducting separate trials within subgroups may lead to infeasibly small sample sizes in subgroups having low prevalence. Alternatively,it is not obvious how to conduct a single trial while accounting for heterogeneity. To address this problem,we consider a generalization of the continual reassessment method on the basis of a hierarchical Bayesian dose‐toxicity model that borrows strength between subgroups under the assumption that the subgroups are exchangeable. We evaluate a design using this model that includes subgroup‐specific dose selection and safety rules. A simulation study is presented that includes comparison of this method to 3 alternative approaches,on the basis of nonhierarchical models,that make different types of assumptions about within‐subgroup dose‐toxicity curves. The simulations show that the hierarchical model‐based method is recommended in settings where the dose‐toxicity curves are exchangeable between subgroups. We present practical guidelines for application and provide computer programs for trial simulation and conduct.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号