全文获取类型
收费全文 | 2462篇 |
免费 | 57篇 |
国内免费 | 10篇 |
专业分类
管理学 | 124篇 |
劳动科学 | 1篇 |
民族学 | 6篇 |
人口学 | 31篇 |
丛书文集 | 147篇 |
理论方法论 | 76篇 |
综合类 | 1240篇 |
社会学 | 97篇 |
统计学 | 807篇 |
出版年
2024年 | 2篇 |
2023年 | 16篇 |
2022年 | 8篇 |
2021年 | 19篇 |
2020年 | 30篇 |
2019年 | 49篇 |
2018年 | 50篇 |
2017年 | 94篇 |
2016年 | 45篇 |
2015年 | 53篇 |
2014年 | 103篇 |
2013年 | 443篇 |
2012年 | 147篇 |
2011年 | 107篇 |
2010年 | 95篇 |
2009年 | 101篇 |
2008年 | 104篇 |
2007年 | 113篇 |
2006年 | 94篇 |
2005年 | 106篇 |
2004年 | 95篇 |
2003年 | 84篇 |
2002年 | 59篇 |
2001年 | 77篇 |
2000年 | 73篇 |
1999年 | 55篇 |
1998年 | 40篇 |
1997年 | 36篇 |
1996年 | 46篇 |
1995年 | 37篇 |
1994年 | 29篇 |
1993年 | 13篇 |
1992年 | 21篇 |
1991年 | 6篇 |
1990年 | 21篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 2篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 4篇 |
排序方式: 共有2529条查询结果,搜索用时 15 毫秒
1.
《Risk analysis》2018,38(9):1988-2009
Harbor seals in Iliamna Lake, Alaska, are a small, isolated population, and one of only two freshwater populations of harbor seals in the world, yet little is known about their abundance or risk for extinction. Bayesian hierarchical models were used to estimate abundance and trend of this population. Observational models were developed from aerial survey and harvest data, and they included effects for time of year and time of day on survey counts. Underlying models of abundance and trend were based on a Leslie matrix model that used prior information on vital rates from the literature. We developed three scenarios for variability in the priors and used them as part of a sensitivity analysis. The models were fitted using Markov chain Monte Carlo methods. The population production rate implied by the vital rate estimates was about 5% per year, very similar to the average annual harvest rate. After a period of growth in the 1980s, the population appears to be relatively stable at around 400 individuals. A population viability analysis assessing the risk of quasi‐extinction, defined as any reduction to 50 animals or below in the next 100 years, ranged from 1% to 3%, depending on the prior scenario. Although this is moderately low risk, it does not include genetic or catastrophic environmental events, which may have occurred to the population in the past, so our results should be applied cautiously. 相似文献
2.
Aggressive behavior in pet dogs is a serious problem for dog owners across the globe, with bite injuries representing a serious risk to both people and other dogs. The effective management of aggressive behavior in dogs represents a challenging and controversial issue. Although positive reinforcement training methods are now considered to be the most effective and humane technique to manage the risk of aggression, punishment‐based methods continue to be used. Unfortunately, there has been little scientific study into the various factors influencing whether dog owners choose to use positive reinforcement techniques to manage aggression in their dogs. As such, current understanding of how best to encourage and support dog owners to use these methods remains extremely limited. This article uses a survey methodology based on protection motivation theory (PMT) to investigate the factors that influence owner use of positive reinforcement methods to manage aggressive behavior, in an attempt to understand potential barriers and drivers of use. In addition, the article provides an initial exploration of the potential role of wider psychological factors, including owner emotional state, social influence, and cognitive bias. Findings show that the perceived efficacy of positive reinforcement methods and the perceived ability of owners to effectively implement the technique are both key factors predicting future intentions and current reported use. Future interventions should focus on enhancing owner confidence in the effective use of positive reinforcement techniques across multiple scenarios, as well as helping owners manage their own emotional responses when they encounter challenging situations and setbacks. 相似文献
3.
4.
Hadi Emami 《统计学通讯:理论与方法》2020,49(8):1793-1800
AbstractIn this article we develop the minimax estimation approach of general linear models to the semiparametric linear models when the parameters are simultaneously constrained by an ellipsoid and linear restrictions. Combining sample information and prior constraints the minimax estimator is obtained and compared with partially least square estimator by theoretical and simulation methods. 相似文献
5.
6.
袁晖坪 《上海理工大学学报(社会科学版)》2002,24(3):214-217,221
给出了复亚半正定矩阵的概念,研究了它的基本性质及行列式理论,将Hermite阵的Schur定理,华罗庚定理,Minkowski不等式,凸性不等式,Ostrowski-Taussky不等式推广到了较广泛的复矩阵类,扩大了Minkowski不等式的指数范围,削弱了华罗庚不等式的条件。 相似文献
7.
天波 《广西师范学院学报(哲学社会科学版)》2002,23(2):62-65
乾隆三十三年 ,纪昀因为“漏言”被谪贬至西域乌鲁木齐。与古代其他谪贬文人所不同的是 ,他并未完全沉浸于穷愁怨艾的情绪中 ,而是以积极乐观的人生态度面对现实。他的《乌鲁木齐杂诗》及《阅微草堂笔记》多方面地展示了西域的风土人情。但两者在内容及视角上有所不同 ,《乌鲁木齐杂诗》以丰富见长 ,但多粉饰之意 ;《阅微草堂笔记》以深刻取胜 ,真实而颇见其洞察力 相似文献
8.
考虑用 4个长为 2 n - 2 的Bent序列或线性序列级联构造Bent序列的问题 ,给出了第二类线性基Bent序列的类型以及级联序列为第二类Bent基Bent序列的一个充分条件 . 相似文献
9.
讨论增长曲线模型Y =X1BX2 +ε中回归矩阵B的函数C1BC2 的估计L1YL2 +A ,在矩阵损失 (LT2 L1)Y +A - (ST2 XT2 S1X1)B (LT2 L1)Y +A - (ST2 XT2 S1X1)B T 下 ,我们得到了非齐次线性估计L1YL2 +A在非齐次线性估计类Г ={L1YL2 +A|L1:t×p ,L2 ;n×n ,A :t×s均为已知实阵 }中可容许的充要条件 :L1YL2在Г0 ={L1YL2 |L1:t×p ,L2 :n×s均为已知实阵 }中容许且当LT2 XT2 L1X1=ST2 XT2 S1X1时有A =0。 相似文献
10.
The problem considered is that of finding an optimum measurement schedule to estimate population parameters in a nonlinear model when the patient effects are random. The paper presents examples of the use of sensitivity functions, derived from the General Equivalence Theorem for D-optimality, in the construction of optimum population designs for such schedules. With independent observations, the theorem applies to the potential inclusion of a single observation. However, in population designs the observations are correlated and the theorem applies to the inclusion of an additional measurement schedule. In one example, three groups of patients of differing size are subject to distinct schedules. Numerical, as opposed to analytical, calculation of the sensitivity function is advocated. The required covariances of the observations are found by simulation. 相似文献