全文获取类型
收费全文 | 7287篇 |
免费 | 104篇 |
国内免费 | 26篇 |
专业分类
教育 | 5177篇 |
科学研究 | 577篇 |
各国文化 | 112篇 |
体育 | 594篇 |
综合类 | 39篇 |
文化理论 | 116篇 |
信息传播 | 802篇 |
出版年
2023年 | 20篇 |
2022年 | 36篇 |
2021年 | 103篇 |
2020年 | 175篇 |
2019年 | 225篇 |
2018年 | 241篇 |
2017年 | 279篇 |
2016年 | 256篇 |
2015年 | 195篇 |
2014年 | 231篇 |
2013年 | 1395篇 |
2012年 | 252篇 |
2011年 | 268篇 |
2010年 | 239篇 |
2009年 | 205篇 |
2008年 | 253篇 |
2007年 | 274篇 |
2006年 | 226篇 |
2005年 | 209篇 |
2004年 | 174篇 |
2003年 | 178篇 |
2002年 | 161篇 |
2001年 | 139篇 |
2000年 | 132篇 |
1999年 | 84篇 |
1998年 | 75篇 |
1997年 | 91篇 |
1996年 | 89篇 |
1995年 | 64篇 |
1994年 | 77篇 |
1993年 | 68篇 |
1992年 | 80篇 |
1991年 | 62篇 |
1990年 | 63篇 |
1989年 | 51篇 |
1988年 | 60篇 |
1987年 | 44篇 |
1986年 | 55篇 |
1985年 | 63篇 |
1984年 | 60篇 |
1983年 | 60篇 |
1982年 | 47篇 |
1981年 | 40篇 |
1980年 | 41篇 |
1979年 | 45篇 |
1978年 | 47篇 |
1977年 | 29篇 |
1976年 | 25篇 |
1975年 | 18篇 |
1948年 | 18篇 |
排序方式: 共有7417条查询结果,搜索用时 15 毫秒
81.
In a study of 243 firms of varying sizes across 14 different industries, we investigate the effect of customer participation on new product development performance. We confirm that overall customer participation is positively related to new product development performance and that the effect is mediated by innovativeness. We also demonstrate that these effects are contingent upon absorptive capacity of the firm in question such that firms with high absorptive capacity stand to gain more from engaging their customers in new product development than firms with low absorptive capacity, especially at the later stages of the NPD process. The results are robust to alternative estimation techniques, measures employed to operationalize key concepts, and the industrial makeup of the sample. Post hoc analyses provide non-trivial managerial implications for the decision makers at the firm level. 相似文献
82.
83.
Chunjia Han Stephen Rhys Thomas Mu Yang Petros Ieromonachou Hongru Zhang 《The Journal of High Technology Management Research》2017,28(1):93-109
Research and development (R&D) investment activity plays a crucial role in developing high-tech industries. In recent decades, China has made sustained investments in its domestic high-tech industries, with the goal of increasing their productivity. This paper investigates the effect of this investment on relative R&D efficiency across China's high-tech sectors. Data Envelopment Analysis (DEA) was used to generate quantitative indices for sector comparisons. The analysis of this study indicates that overall R&D investment efficiency did not increase from 1998 to 2009, despite R&D expenditure increasing by 2188%. Over the same period, most sectors suffered from decreasing returns to scale (DRS), presumably also reflecting the inefficient R&D investment. Most of the sectors showed significant fluctuation on R&D investment efficiency. This research result indicates that the problem of China's high-tech industry may be from the inefficiency of its technology commercialization processes, and therefore represents a critical parameter for policy makers and managers. 相似文献
84.
Salmanzadeh A Kittur H Sano MB C Roberts P Schmelz EM Davalos RV 《Biomicrofluidics》2012,6(2):24104-2410413
Ovarian cancer is the leading cause of death from gynecological malignancies in women. The primary challenge is the detection of the cancer at an early stage, since this drastically increases the survival rate. In this study we investigated the dielectrophoretic responses of progressive stages of mouse ovarian surface epithelial (MOSE) cells, as well as mouse fibroblast and macrophage cell lines, utilizing contactless dielectrophoresis (cDEP). cDEP is a relatively new cell manipulation technique that has addressed some of the challenges of conventional dielectrophoretic methods. To evaluate our microfluidic device performance, we computationally studied the effects of altering various geometrical parameters, such as the size and arrangement of insulating structures, on dielectrophoretic and drag forces. We found that the trapping voltage of MOSE cells increases as the cells progress from a non-tumorigenic, benign cell to a tumorigenic, malignant phenotype. Additionally, all MOSE cells display unique behavior compared to fibroblasts and macrophages, representing normal and inflammatory cells found in the peritoneal fluid. Based on these findings, we predict that cDEP can be utilized for isolation of ovarian cancer cells from peritoneal fluid as an early cancer detection tool. 相似文献
85.
图书馆知识管理能力评价是其实施知识管理战略的重要组成部分,是加快知识创新步伐、改善知识管理平台、提高知识管理能力的重要手段。借鉴软件开发的能力成熟度模型,提出图书馆知识管理能力成熟度模型框架,构建科学合理、全面客观的图书馆知识管理能力评价指标体系,并以某高校图书馆为例进行实证研究,以期为图书馆知识管理者改善工作,正确指导图书馆知识管理的发展提供新的思路与途径。 相似文献
86.
87.
88.
89.
在由一个制造商和一个零售商组成的制造商回收再制造闭环供应链中,考虑系统成员间存在Nash均衡博弈、制造商领导的Stackelberg博弈和零售商领导的Stackelberg博弈等权利关系,研究并比较三种分散式决策闭环供应链的定价决策及利润问题。研究结论表明:在制造商领导的市场中,零售商的零售价与获得产品的批发价呈正相关关系;在零售商领导的市场中,制造商的批发价和回收率均与零售商的零售价呈负相关关系;回收产品的潜在期望收益是回收行为的驱动因素;在分散式决策闭环供应链中,市场无领导者时,消费者获得的收益最多,闭环供应链也越有利于降低资源消耗,且制造商和零售商均有动机成为领导者,其拥有的权利越大,议价能力会越强,获得的利润就会越多;与分散式决策相比,集中式决策闭环供应链的零售价最低,回收率和渠道总利润最高。最后,我们设计了可协调三种分散式决策闭环供应链的收益共享契约。 相似文献
90.