全文获取类型
收费全文 | 7265篇 |
免费 | 642篇 |
国内免费 | 103篇 |
学科分类
自然科学 | 8010篇 |
出版年
2018年 | 733篇 |
2017年 | 738篇 |
2016年 | 445篇 |
2015年 | 58篇 |
2014年 | 44篇 |
2013年 | 38篇 |
2012年 | 293篇 |
2011年 | 1000篇 |
2010年 | 847篇 |
2009年 | 483篇 |
2008年 | 546篇 |
2007年 | 805篇 |
2006年 | 52篇 |
2005年 | 95篇 |
2004年 | 205篇 |
2003年 | 314篇 |
2002年 | 350篇 |
2001年 | 198篇 |
2000年 | 129篇 |
1999年 | 86篇 |
1997年 | 15篇 |
1996年 | 23篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 20篇 |
1992年 | 15篇 |
1991年 | 16篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1982年 | 11篇 |
1980年 | 11篇 |
1979年 | 20篇 |
1978年 | 19篇 |
1977年 | 20篇 |
1976年 | 20篇 |
1975年 | 12篇 |
1974年 | 21篇 |
1973年 | 10篇 |
1972年 | 17篇 |
1971年 | 17篇 |
1970年 | 30篇 |
1969年 | 20篇 |
1968年 | 15篇 |
1967年 | 15篇 |
1966年 | 19篇 |
1965年 | 16篇 |
1964年 | 10篇 |
排序方式: 共有8010条查询结果,搜索用时 15 毫秒
1.
LuJian-ke 《武汉大学学报:自然科学英文版》2004,9(1):1-5
The homogeneous quadratic Riemann boundary value problem (1) with Hoelder continuous coefficients for the normal case was considered by the author in 1997. But the solutions obtained there are incomplete. Here its general method of solution is obtained. 相似文献
2.
Static extracting method of software intended behavior based on API functions invoking 总被引:1,自引:0,他引:1
The method of extracting and describing the intended behavior of software precisely has become one of the key points in the fields of software behavior's dynamic and trusted authentication. In this paper, the author proposes a specified measure of extracting SIBDS (software intended behaviors describing sets) statically from the binary executable using the software's API functions invoking, and also introduces the definition of the structure used to store the SIBDS in detail. Experimental results demonstrate that the extracting method and the storage structure definition offers three strong properties: (i) it can describe the software's intended behavior accurately; (ii) it demands a small storage expense; (iii) it provides strong capability to defend against mimicry attack. 相似文献
3.
WANG Xibo ZHOU Benhai YU Gei LI Qian 《武汉大学学报:自然科学英文版》2007,12(5):946-950
μC/OS-Ⅱ is an open source real-time kernel adopting priority preemptive schedule strategy. Aiming at the problem of μC/OS-Ⅱ failing to support homology priority tasks scheduling, an approach for solution is proposed. The basic idea is adding round-robin scheduling strategy in its original scheduler in order to schedule homology priority tasks through time slice roundrobin. Implementation approach is given in detail. Firstly, the Task Control Block (TCB) is extended. And then, a new priority index table is created, in which each index pointer points to a set of homology priority tasks. Eventually, on the basis of reconstructing μC/OS-Ⅱ real-time kernel, task scheduling module is rewritten. Otherwise, schedulability of homology task supported by modified kernel had been analyzed, and deadline formula of created homology tasks is given. By theoretical analysis and experiment verification, the modified kernel can support homology priority tasks scheduling, meanwhile, it also remains preemptive property of original μC/OS-Ⅱ. 相似文献
4.
The exponential Radon transform, a generalization of the Radon transform, is defined and studied as a mapping of function
spaces. It is represented in terms of Fourier transform of its domain and range, and this leads to the harmonic decomposition
reconstruction. The results are similar results of Tretiak and Metz.
Foundation item: Supported by the National Natural Science Foundation of China (No. 19971064), Key Project of Science and
Technology of Hubei Province Education Committee.
Biography: Wang Jin-ping (1963-), male, Ph.D. candidate, research direction: numberical solution of singular integral equation
and integral transformation etc. 相似文献
5.
YU Jianqiao LIAO Jianwei 《武汉大学学报:自然科学英文版》2007,12(5):887-892
We propose a multiple-tree overlay structure for resource discovery in unstructured P2P systems. Peers that have similar interests or hold similar type of resources will be grouped into a tree-like cluster. We exploit the heterogeneity of peers in each cluster by connecting peers with more capacities closer to the root of the tree. The capacity of a peer can be defined in different ways (e.g. higher network bandwidth, larger disk space, more data items of a certain type etc.) according to different needs of users or applications. 相似文献
6.
In October 1924, The Physical Review, a relatively minor journal at the time, published a remarkable two-part paper by John H. Van Vleck, working in virtual isolation
at the University of Minnesota. Using Bohr’s correspondence principle and Einstein’s quantum theory of radiation along with
advanced techniques from classical mechanics, Van Vleck showed that quantum formulae for emission, absorption, and dispersion
of radiation merge with their classical counterparts in the limit of high quantum numbers. For modern readers Van Vleck’s
paper is much easier to follow than the famous paper by Kramers and Heisenberg on dispersion theory, which covers similar
terrain and is widely credited to have led directly to Heisenberg’s Umdeutung paper. This makes Van Vleck’s paper extremely valuable for the reconstruction of the genesis of matrix mechanics. It also
makes it tempting to ask why Van Vleck did not take the next step and develop matrix mechanics himself.
This paper was written as part of a joint project in the history of quantum physics of the Max Planck Institut für Wissenschaftsgeschichte and the Fritz-Haber-Institut in Berlin. 相似文献
7.
DING Mingtao WEI Fangqiang ZHANG Jinghong WANG Hongjuan 《武汉大学学报:自然科学英文版》2007,12(4):599-604
By analyzing the observation data from Dongchuan Debris Flow Observation and Research Station and historical data from year 1965 to 1990 gotten from National Astronomical Ob-servatories/Yunnan Observatory,the responding of debris flow in Jiangjia Ravine to Solar Proton Flare is studied. The following conclusion can be drawn. Solar Proton Flare,as one of most im-portant astronomical factors,affects the activity of debris flow in Yunnan. Generally,from 1965 to1990,the more active Solar Pro-ton Flare is,the greater the probability of high frequency and large runoff of debris flow is. On the contrary,the less active Solar Pro-ton Flare is,the greater the probability of low frequency,small runoff,and low sediment transport of debris flow is. 相似文献
8.
许德生 《安徽工程科技学院学报:自然科学版》2002,17(4):24-26
简述TiO2、ZnO陶瓷粉纳米材料的性能、TiO2、ZnO陶瓷粉纳米功能性粘胶纤维的研制方法及含TiO2、ZnO等陶瓷粉纳米功能性粘胶纤维及其织物的性能分析.试验表明,用纳米材料制成的粘胶长丝与绦纶长丝复合丝(3.4tex/30f)制成的织物耐洗色率度、耐摩色率度、耐汗渍色牢度、燃烧性能均有不同程度改善,织物的服用性能提高,并具有屏蔽和抗菌性能. 相似文献
9.
估计两个单属性关系在连接属性上取相同值的个数的方法有两种:静态估计法和动态估计法.本文利用不精确性推理模型对这两种方法的可信度定量地进行讨论,并用具体例子进行说明. 相似文献
10.
赵德建 《江苏技术师范学院学报》2003,9(2):65-67,74
现行《化学教学论》教材将典型教学示例放在化学教学原则之后,致使整本教材缺乏逻辑性,不符合当前创新能力培养的要求,不利于坚定师范生从事教育事业的信心,笔者认为应先讲教学示例、后授教学原则。 相似文献