全文获取类型
收费全文 | 5150篇 |
免费 | 71篇 |
国内免费 | 66篇 |
专业分类
教育 | 3535篇 |
科学研究 | 640篇 |
各国文化 | 28篇 |
体育 | 379篇 |
综合类 | 228篇 |
文化理论 | 59篇 |
信息传播 | 418篇 |
出版年
2023年 | 18篇 |
2022年 | 70篇 |
2021年 | 143篇 |
2020年 | 120篇 |
2019年 | 122篇 |
2018年 | 137篇 |
2017年 | 146篇 |
2016年 | 131篇 |
2015年 | 186篇 |
2014年 | 256篇 |
2013年 | 547篇 |
2012年 | 358篇 |
2011年 | 320篇 |
2010年 | 297篇 |
2009年 | 329篇 |
2008年 | 300篇 |
2007年 | 333篇 |
2006年 | 293篇 |
2005年 | 252篇 |
2004年 | 153篇 |
2003年 | 145篇 |
2002年 | 152篇 |
2001年 | 145篇 |
2000年 | 79篇 |
1999年 | 47篇 |
1998年 | 29篇 |
1997年 | 18篇 |
1996年 | 25篇 |
1995年 | 15篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有5287条查询结果,搜索用时 15 毫秒
61.
62.
设计索引的目的是为了加快数据检索.文章就与索引相关的一些特征元素.提出了创建索引中数据目录项的3种不同方法.同时对B^ 索引进行了描述.分析了其在进行数据搜索的实现原理.简要个绍了在实现数据删除和插入时的优化思路. 相似文献
63.
基于关键帧的视像检索研究 总被引:1,自引:0,他引:1
在分析视像数据结构的基础上,介绍了基于关键帧的颜色和纹理特征的提取方法,并给出了具体的训练及测试流程. 相似文献
64.
65.
私营企业主能否入党是一个众说纷纭的敏感问题。我们认为有中国特色社会主义事业的建设的定性决定了优秀的私营企业主可以入党;发展优秀的私营主入党是扩大党的群众基础的需要。在发展优秀的私营企业主入党问题上,应该把握好发展党员的方针政策、原则和程序以及对优秀私营企业主的考察培养。 相似文献
66.
67.
Chang Xin Zhang Chengyu Gao Lan Liu Xiao You Shengping Qi Wei Wang Kang Guo Xin Su Rongxin Lu Han He Zhimin 《天津大学学报(英文版)》2019,25(5):488-496
2,5-Furandicarboxylic acid(FDCA) is a potential biorenewable chemical for applications including plastics, polyamides, drugs, etc. The selective biosynthesis of FDCA from 5-hydroxymethylfurfural(HMF) by a specific enzyme poses a great challenge. In this study, we reported an efficient strategy to produce FDCA from HMF by the tandem biocatalysis of laccase(Cot A-TJ102@UIO-66-NH_2) and Novozym 435. For the first step, a nanoparticle metal–organic framework was synthesized as a carrier to immobilize Cot A-TJ102@UIO-66-NH_2, which was assigned for the production of 5-formyl-2-furancarboxylic acid(FFCA) and featured an enzyme loading of 255.54 mg/g, specific activity of 135.90 U/mg, and solid loading ratio of 99.65%. Under optimal conditions, an ideal FFCA yield of 98.5% was achieved, and the Cot A-TJ102@UIO-66-NH_2 presented a high recycling capacity after 10 cycles. For the second step, Novozym 435 was applied for the further conversion of FFCA into FDCA, presenting a high FDCA yield of 95.5% under the optimized conditions. Novozym 435 also exhibited a high recyclability after eight cycles. As a result, the tandem biocatalysis strategy provided a 94.2% FDCA yield from HMF, indicating its excellence as a method for FDCA production. 相似文献
68.
吴兰 《连云港师范高等专科学校学报》2004,(3):89-91
文章介绍了在Authorware多媒体软件中实用性很好的组建整体结构的三种方法:常见交互图标应用法、导航图标应用法、文字超级链接法。将课件中的多种信息模块化地组织在一起,为课件制作者带来很大的方便性和灵活性,且在媒体软件制作方面有着广泛的应用。 相似文献
69.
Objective: We aim to describe the environment iodine concentration in salt, water and soil along Zhejiang Province coast in the China foreland. It will be helpful for us to judge whether this area is insufficient in iodine and universal iodized salt is necessary or not. Methods: We collected iodized salt samples, drinking water samples (tap water in the towns, and well water or spring water in the villages), water samples from different sources (ditches, lakes, rivers) and soil samples through random sampling in June, 2005. Salt, water and soil iodine was detected by arsenic-cerium redox method. Statistical analysis was expressed as mean±SEMby Windows SPSS 13.0. Results: (1) The iodine concentration in salt was 27.9±4.33 mg/kg (n=108). (2) Seventy-five water samples were collected. The water iodine value was 0.6~84.8 μg/L (mean of 11.66 μg/L). The watershed along the Qiantang River has significantly higher iodine content than the water in Lin'an in mountain area (P<0.01). The iodine content and mean iodine content of tap water, well or spring water and natural water sources were 4.30±2.43 μg/L (n=34), 23.59±27.74 μg/L (n=19)and 12.72±10.72 μg/L (n=22) respectively. This indicated that among environmental water sources, the ditch iodine content was the highest with river water iodine being the lowest (P<0.01). (3) Soil iodine value was 0.11~2.93 mg/kg (mean of 1.32 mg/kg).Though there was no statistical difference of soil iodine in different districts (P=0.131), soil iodine content correlated positively with water iodine content. Conclusion: Iodine concentration in salt accords with national policy of adding iodine in salt. Foreland has more iodine in water than mountain area. The data reflected that water and soil iodine in foreland area was not high, which suggests universal iodized salt should be necessary. Environment iodine has relatively close association with pollution. 相似文献
70.
Research Findings: This study explores the beliefs, self-reported practices, and observed practices of Turkish preschool teachers toward children’s peer relationship problems as well as the gap between their beliefs and practices. Five female teachers of 5-year-old children were selected as participants for this multiple case study. Approximately 79 hr of observation was conducted on the children’s daily routines and activities in a natural classroom environment, which specifically included the teachers’ problem-solving strategies while confronting peer relationship problems. The participants were also interviewed regarding their beliefs and strategies for solving peer relationship problems. The findings of this qualitative investigation indicated that the teachers’ beliefs and self-reported practices included both teacher- and child-related factors. However, the observed practices included several teacher-initiated strategies; child-initiated strategies appeared, albeit less than teacher-initiated ones. This affirms the teachers’ stress on children’s role in managing peer problems. Although some of the teacher practices and beliefs were consistent, certain inconsistencies may indicate the presence of external constraints. Practice or Policy: The results of this study highlight the importance of teacher education programs providing preservice and in-service teachers with the knowledge and skills required to understand children’s peer relationships, guide their interactions, and apply appropriate intervention strategies for various peer relationship problems. 相似文献