全文获取类型
收费全文 | 89941篇 |
免费 | 10448篇 |
国内免费 | 10468篇 |
专业分类
系统科学 | 3199篇 |
丛书文集 | 2153篇 |
教育与普及 | 2296篇 |
理论与方法论 | 300篇 |
现状及发展 | 667篇 |
研究方法 | 207篇 |
综合类 | 102024篇 |
自然研究 | 11篇 |
出版年
2024年 | 311篇 |
2023年 | 887篇 |
2022年 | 1100篇 |
2021年 | 1387篇 |
2020年 | 1641篇 |
2019年 | 3685篇 |
2018年 | 3909篇 |
2017年 | 4197篇 |
2016年 | 4390篇 |
2015年 | 4749篇 |
2014年 | 5298篇 |
2013年 | 4524篇 |
2012年 | 4151篇 |
2011年 | 4962篇 |
2010年 | 4459篇 |
2009年 | 4516篇 |
2008年 | 3904篇 |
2007年 | 3667篇 |
2006年 | 2767篇 |
2005年 | 2810篇 |
2004年 | 3545篇 |
2003年 | 2828篇 |
2002年 | 2535篇 |
2001年 | 2085篇 |
2000年 | 1992篇 |
1999年 | 3329篇 |
1998年 | 3281篇 |
1997年 | 3483篇 |
1996年 | 2797篇 |
1995年 | 2407篇 |
1994年 | 2555篇 |
1993年 | 2582篇 |
1992年 | 2144篇 |
1991年 | 1977篇 |
1990年 | 1676篇 |
1989年 | 1356篇 |
1988年 | 1140篇 |
1987年 | 762篇 |
1986年 | 519篇 |
1985年 | 201篇 |
1984年 | 66篇 |
1983年 | 23篇 |
1982年 | 20篇 |
1977年 | 25篇 |
1974年 | 9篇 |
1972年 | 66篇 |
1970年 | 10篇 |
1969年 | 9篇 |
1968年 | 14篇 |
1967年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
91.
王耀富 《黔西南民族师范高等专科学校学报》2008,(3):100-104
通过介绍几个经济管理中的典型案例,探索了经济和管理中错误的变化或转化的条件、方式和规律。在介绍模糊错误集得出几个基本概念的同时,主要研究了模糊错误集分解运算与内涵对立运算的关系,得到了1个定理。 相似文献
92.
在考察针刺穴位治疗作用的基础上,根据现有的实验事实,将人体经络的观念和经改进后的神经-内分泌-免疫系统的观念统一起来,提出人体经络是具有敏感节点和功能连接的神经-内分泌-免疫网络的假说。人体经络的复杂网络不仅是遍及全身的系统,而且可以通过敏感节点及其功能连接对身体起调控作用。 相似文献
93.
高新技术是高科技与新技术的组合,相对于一般传统技术而言的新兴尖端技术,它包含了以电子信息技术、生物技术、新材料技术、新能源技术和航天技术等为代表的高新技术群. 相似文献
94.
在科技迅速发展的今天,信息化管理及其人们对新信息的需求程度不断提高,计算机技术的应用日益深入到各行各列,西藏高校的"计算机文化"课程的教学方法和考核方式都迫切需要改革。文章在教学实践的基础上,对我区高校"计算机文化"课程的教学方法及考核方式改革进行了探索。 相似文献
95.
96.
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
97.
High-density event-related potentials (ERPs) were measured when participants were required to evaluate oneself, significant others (father and mother) and the most familiar public figures (Lei Feng and Jiang Qing) based on trait adjectives. There were three referential conditions and a non-referential control condition including self-evaluation (SE), significant other-evaluation (SOE), general other-evaluation (GOE), and semantic positivity-evaluation (SPE). The behavioral data showed that RTs to GOE condition were longer than the other three conditions. Scalp ERP analysis revealed that (1) SPE condition elicited a more negative N2 than SE condition, which was associated with inhibition of responses; (2) SE condition elicited a more positive P300 than SPE condition, which was an index of attention to self-relevant stimuli; (3) there was no difference on the amplitude and latency of P300 between SE and SOE conditions, which reflected that the concept of “self” included intimate others (e.g., father and mother) in Chinese culture. 相似文献
98.
99.
莱钢特钢厂20CrMnTiH钢材成分波动较大,淬透性带HRC8~10,范围较大,制约了齿轮钢质量的进一步提高.通过研究,发现铸坯中心偏析尤其是碳偏析为主要问题.通过工艺优化采取各项措施,尤其增加电磁搅拌后,中心碳偏析得到明显改善;C控制在0.19%~0.20%的炉次达到了95.6%;淬透性带控制在HRC6内的达到了92.1%;在HRC4内的达到了86.2%;提高了产品质量,满足了用户需求. 相似文献
100.
Duan Jinqing Liu Hongbin Zhang Xinian Lu Hongmin Gou Ai Liu Zheng Wang Tao Ge Rili 《中国工程科学》2006,4(2):183-186
Study Objective: To compare and analyze the changes of the pulmonary-artery pressure of the migrants coming from different elevation in the hypoxic environment of 4636 - 4907 m extreme altitude. To explore the susceptibility to hypoxic pulmonary-artery hypertension (PH) in the subjects from different altitude and profession. Methods: By using Color Doppler Ultmsonography (CDU), measuring the pulmonary-artery pressure of 207 healthy men, who had continuously being lived and worked at the extreme altitude for more than six months, and then were divided into three groups according to their profession and the altitude of original living place. Results: There was a significant difference in the outcomes of pulmonary-artery pressure from the 3 groups. Conclusions: Altitude of original living place, labor intensity are some of factors that impact the pulmonary-artery pressure of the people who exposure to a hypoxic environment. The pulmonary- artery pressure of person without strenuously physical work experience was more sensitive to hypoxic surroundings than that of labor workers. It was not always the fact at an extreme altitude that the moderate altitude mountaineers were superior to other migrants from a lower altitude or plain. The higher PH was found in the groups of the moderate altitude mountaineers and labor workers. It is unlikely certain that one with PH would surfer from HAPE. 相似文献