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81.
分析了非共沸混合工质水平管内环状流型下强制对流蒸发的局部换热系数的计算方法,推导出局部换热系数的计算公式,并分析了影响非共沸混合工质蒸发换热的主要因素.利用本文公式得出的预测值与实验数据比较,取得了一致的结果  相似文献   
82.
根据一般动力学系统在相空间的作用积分在无穷小群变换下的变换性质,分别建立起完整和非完整非保守系统的Noether定理和逆定理.由给出的例子表明,在相空间中可以呈现出动力学系统新的对称性.  相似文献   
83.
用流体动力学模型研究一维流体的集体效应和相变对末态粒子分布的影响,结果表明:在RHIC-LHC能区有相变和无相变时的末态快度分布形状是很不相同的,预计快度分部的形状可作为夸克物质形成的信号。  相似文献   
84.
本文综合论述了1987年以来超导研究发展的动态、进展和预言了超导发展的前景。文章简述了超导物理学发展简史,并就超导起始转变温度、临界电流密度、超导线材、超导薄膜、超导器件、超导制备工艺、超导组分、超导相结构以及超导理论方面的进展分别作了介绍。并对超导发展的方向作了一定的评述。  相似文献   
85.
应用流体动力学模型,分别采用包含相变的状态方程和不含相变的状态方程,计算了每对核子能量为100GeV~(197)Au—~(197)Au 碰撞的末态碎裂时空分布、末态快度分布,并分析讨论了影响末态分布的因素.  相似文献   
86.
冲击型负荷下的生产存储模型研究   总被引:1,自引:0,他引:1  
建立了考虑冲击需求、变化生产率的最优生产存储库存策略. 其特点是:把一个生产周 期分为多个生产阶段,各个生产阶段时间可以不同;在每个生产阶段中,允许生产率小于需求 率,允许提前生产;而且,最大生产率要小于最大需求率. 研究发现,为满足冲击需求,提前存储 较多而启动机器数量较少,或提前存储较少而启动机器数量较多,不一定能够取得最佳效益, 要根据存储费用和启动费用共同确定. 在有限生产率的条件下,得出一种寻求最优生产- 库存 策略,为此类库存系统的管理决策提供了理论依据.  相似文献   
87.
过渡时期:向哪里过渡?   总被引:1,自引:0,他引:1  
石镇平 《河北学刊》2005,25(6):10-16
马克思所说的过渡时期是向共产主义社会第一阶段过渡,而不是向共产主义社会高级阶段过渡;而向共产主义社会第一阶段过渡,仅仅完成消灭剥削阶级的任务是远远不够的,还必须完成消灭阶级的历史任务。20世纪以来社会主义实践中存在的一个重要问题,就是提前宣布进入社会主义,混淆了过渡时期与共产主义社会第一阶段的界限,造成了理论与实践之间的严重错位。  相似文献   
88.
Adoption and permanence planning has been a key feature of Scotland's policy in relation to children and young people who are “looked after.” Although policy and law has significantly developed in recent years, there has been comparatively little research on permanence processes in Scotland. This paper outlines key findings from the first comprehensive study of permanence planning in Scotland. It examines the process for two cohorts of children where adoption or other types of permanence orders were made. The children were selected under the long standing Adoption (Scotland) Act 1978 and the more recent Adoption and Children (Scotland) Act 2007. In total, 300 cases were examined, analysing data from the children's first contact with services through to the order made by the Scottish Courts. This paper pays particular attention to the timescales found at key stages under the two sets of legislation and asks what difference the change in legislation has made.  相似文献   
89.
Research concerning outcomes for children who have been placed in out‐of‐home care has indicated that the care may have unwanted consequences. However, there has been no coherent terminology for differentiating between different types of such unwanted consequences. In this article therefore, we attempt to disentangle different aspects of potentially harmful care for looked after children, as well as to discuss potential pathways to more systematically approach and report adverse events for this group. In this endeavour, we turn to two adjacent disciplines, medicine and psychology, where these issues have received more interest. The applicability of the concepts used in these fields is discussed, and it is concluded that although they provide some help in categorizing different aspects of harmful care, the complexity of out‐of‐home care makes existing models difficult to adopt without adjustments. This has consequences for the possibility of evaluating care in research, as well as for monitoring adverse events in practice. Importantly, the causality will often be unknown. We therefore suggest that it is essential to shed more light on how decisions should be made about when to intervene or not in out‐of‐home care, despite limited information.  相似文献   
90.
The Simon's two‐stage design is the most commonly applied among multi‐stage designs in phase IIA clinical trials. It combines the sample sizes at the two stages in order to minimize either the expected or the maximum sample size. When the uncertainty about pre‐trial beliefs on the expected or desired response rate is high, a Bayesian alternative should be considered since it allows to deal with the entire distribution of the parameter of interest in a more natural way. In this setting, a crucial issue is how to construct a distribution from the available summaries to use as a clinical prior in a Bayesian design. In this work, we explore the Bayesian counterparts of the Simon's two‐stage design based on the predictive version of the single threshold design. This design requires specifying two prior distributions: the analysis prior, which is used to compute the posterior probabilities, and the design prior, which is employed to obtain the prior predictive distribution. While the usual approach is to build beta priors for carrying out a conjugate analysis, we derived both the analysis and the design distributions through linear combinations of B‐splines. The motivating example is the planning of the phase IIA two‐stage trial on anti‐HER2 DNA vaccine in breast cancer, where initial beliefs formed from elicited experts' opinions and historical data showed a high level of uncertainty. In a sample size determination problem, the impact of different priors is evaluated.  相似文献   
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