全文获取类型
收费全文 | 15444篇 |
免费 | 1057篇 |
国内免费 | 534篇 |
专业分类
系统科学 | 1510篇 |
丛书文集 | 304篇 |
教育与普及 | 273篇 |
理论与方法论 | 293篇 |
现状及发展 | 905篇 |
研究方法 | 21篇 |
综合类 | 13727篇 |
自然研究 | 2篇 |
出版年
2024年 | 47篇 |
2023年 | 135篇 |
2022年 | 162篇 |
2021年 | 223篇 |
2020年 | 139篇 |
2019年 | 57篇 |
2018年 | 800篇 |
2017年 | 831篇 |
2016年 | 550篇 |
2015年 | 281篇 |
2014年 | 398篇 |
2013年 | 378篇 |
2012年 | 649篇 |
2011年 | 1396篇 |
2010年 | 1184篇 |
2009年 | 935篇 |
2008年 | 1045篇 |
2007年 | 1316篇 |
2006年 | 429篇 |
2005年 | 528篇 |
2004年 | 456篇 |
2003年 | 410篇 |
2002年 | 376篇 |
2001年 | 314篇 |
2000年 | 329篇 |
1999年 | 468篇 |
1998年 | 427篇 |
1997年 | 460篇 |
1996年 | 378篇 |
1995年 | 342篇 |
1994年 | 292篇 |
1993年 | 277篇 |
1992年 | 213篇 |
1991年 | 189篇 |
1990年 | 171篇 |
1989年 | 155篇 |
1988年 | 145篇 |
1987年 | 83篇 |
1986年 | 45篇 |
1985年 | 14篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1967年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Alexandra Sauer 《Systemic Practice and Action Research》2008,21(6):497-515
The participation of non-state actors in implementation processes is often understood as a means to increase compliance efficiency.
But the implementation of spatial policies frequently focuses on pre-established goals, processes and instruments and thus
renders difficult open discourse and shared decision-making. This paper introduces conflict pattern analysis (CPA) as a tool
that supports the analysis of the actual actor constellation in order to define efficient approaches that avoid common problems
of participatory processes. CPA is a semi-formalised method that helps to identify key-actors, their relations and interaction
amongst each other as well as their core beliefs, interests and resources. It aggregates this information to interaction patterns
that can be compared, classified and linked to different participatory methods on a theoretically informed basis. Particularly
on the local and regional level, this could be the first step for successful (participatory) implementation strategies. 相似文献
92.
S. K. MISHRA Shouyang WANG K. K. LAI 《系统科学与复杂性》2007,20(3):344-349
In this paper, we introduce a new class of generalized convex function, namely, a-pseudounivex function, by combining the concepts of pseudo-univex and α-invex functions. Further, we establish some relationships between vector variational-like inequality problems and vector optimization problems under the assumptions of α-pseudo-univex functions. Results obtained in this paper present a refinement and improvement of previously known results. 相似文献
93.
A theoretical model for mid-and low-latitude ionospheric electric fields in realistic geomagnetic fields 总被引:1,自引:1,他引:0
The geomagnetic fields, which play important roles in the ionospheric dynamo, can greatly affect the global distribution of ionospheric electric fields, currents and other ionospheric electrodynamics phenomena. In the study of ionospheric electrodynamics phenomena, such as the longitudinal variations of ionospheric electric fields, the non-dipolar component of the geomagnetic fields must be taken into account. In this paper, we deduce a theoretical electric field model for ionospheric dynamo at mid- and low-latitude which adopt a modified magnetic apex coordinates system. In the new electric field model, the geomagnetic fields can be calculated from either the IGRF model or the dipole field model, and the neutral winds and conductivities are calculated based on empirical models. Then the dynamo equation for the electric potential is finally solved in terms of the line-by-line iteration method, and the ionospheric electric fields and currents are derived from the calculated potential. Our model can reproduce the main features of the ionospheric electrodynamics processes, so it will be a useful tool for the investigation of the upper atmosphere and ionosphere. 相似文献
94.
医学类专业学分制人才培养方案的改革与实践 总被引:1,自引:0,他引:1
本文介绍了泸州医学院新一轮学分制培养方案的特点,并讲述了从2004年第一次试行学分制到现在,学校对人才培养方案所做的改革和实践。 相似文献
95.
96.
97.
本文根据使用新技术──双回路注(放)水系统在63上10工作面综采放顶煤开采覆岩破坏的探测结果,结合其它采矿方法的实测结果,应用断裂力学理论,研究了放顶煤开采覆岩移动变形破坏特征,为矿井安全生产提供了依据。 相似文献
98.
99.
100.