全文获取类型
收费全文 | 1890篇 |
免费 | 159篇 |
国内免费 | 175篇 |
出版年
2024年 | 8篇 |
2023年 | 40篇 |
2022年 | 37篇 |
2021年 | 41篇 |
2020年 | 54篇 |
2019年 | 83篇 |
2018年 | 61篇 |
2017年 | 73篇 |
2016年 | 64篇 |
2015年 | 76篇 |
2014年 | 125篇 |
2013年 | 116篇 |
2012年 | 99篇 |
2011年 | 113篇 |
2010年 | 80篇 |
2009年 | 105篇 |
2008年 | 111篇 |
2007年 | 111篇 |
2006年 | 115篇 |
2005年 | 69篇 |
2004年 | 82篇 |
2003年 | 73篇 |
2002年 | 81篇 |
2001年 | 52篇 |
2000年 | 40篇 |
1999年 | 30篇 |
1998年 | 33篇 |
1997年 | 17篇 |
1996年 | 33篇 |
1995年 | 22篇 |
1994年 | 22篇 |
1993年 | 24篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 3篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1972年 | 4篇 |
排序方式: 共有2224条查询结果,搜索用时 15 毫秒
1.
Due to the fact that the flood data series of small drainage basins is relatively short, available data are often not sufficient for flood risk analysis. This presents the problem of risk analysis using very small data samples. One method that can be applied is to regard the available small samples as fuzzy information and optimize them using information diffusion technology to yield analytical results with greater reliability. In this article a risk analysis method based on information diffusion theory is applied to create a new flood risk analysis model. Application of the model is illustrated taking the Jinhuajiang and Qujiang drainage basins as examples. This is a new attempt at applying information diffusion theory in flood risk analysis. Computations based on this analytical flood risk model can yield an estimated flood damage value that is relatively accurate. This study indicates that the aforementioned model exhibits fairly stable analytical results, even when using a small set of sample data. The results also indicate that information diffusion technology is highly capable of extracting useful information and therefore improves system recognition accuracy. This method can be easily applied and the analytical results produced are easy to understand. Results are accurate enough to act as a guide in disaster situations. 相似文献
2.
Parvinder Kaur 《Biometrical journal. Biometrische Zeitschrift》1985,27(1):107-110
For the estimation of population mean in simple random sampling, an efficient regression-type estimator is proposed which is more efficient than the conventional regression estimator and hence than mean per unit estimator, ratio and product estimators and many other estimators proposed by various authors. Some numerical examples are included for illustration. 相似文献
3.
Enzymes are remarkable molecules which make metabolism possible. Their processing powers are considerable for not only are they catalysts they also contribute to information processing, integration, coherence and memory in the cell. This complex of attributes suggests that a complementary perspective to enzyme nature and activity is needed related to what enzymes and verbs have in common. The value of this kind of thinking is that it shifts the focus from objects and mechanisms to processes and information. In order to support this idea a number of features which enzymes and verbs share are discussed including, context-dependence, occurrence, cases, voice, mood and glue/integrative capacities. The paper concludes with some reflections on the utility of a view of enzymes as verbs. 相似文献
4.
5.
6.
7.
8.
Hatem A. Howlader Uditha Balasooriya 《Biometrical journal. Biometrische Zeitschrift》2003,45(7):901-912
This paper presents the Bayes estimators of the Poisson distribution function based on complete and truncated data under a natural conjugate prior. Laplace transform of the incomplete gamma function and the Gauss hypergeometric function have been employed in order to overcome the intractability of the integrals. Numerical examples from biosciences are given to illustrate the results. A Monte Carlo study has been carried out to compare Bayes estimators under complete data with the corresponding maximum liklihood estimators. 相似文献
9.
Akaike's information criterion and the histogram 总被引:1,自引:0,他引:1
10.
Adjustments to profile likelihood 总被引:1,自引:0,他引:1