全文获取类型
收费全文 | 675篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
教育 | 429篇 |
科学研究 | 157篇 |
各国文化 | 5篇 |
体育 | 33篇 |
综合类 | 4篇 |
文化理论 | 6篇 |
信息传播 | 59篇 |
出版年
2023年 | 7篇 |
2022年 | 13篇 |
2021年 | 29篇 |
2020年 | 14篇 |
2019年 | 36篇 |
2018年 | 39篇 |
2017年 | 50篇 |
2016年 | 29篇 |
2015年 | 24篇 |
2014年 | 41篇 |
2013年 | 89篇 |
2012年 | 49篇 |
2011年 | 28篇 |
2010年 | 30篇 |
2009年 | 29篇 |
2008年 | 32篇 |
2007年 | 22篇 |
2006年 | 19篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 14篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 3篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有693条查询结果,搜索用时 15 毫秒
11.
12.
Salamatullah Quazi M. Mohiduzzaman Moududur R. Khan B. Nahar M. Mostafizur Rahman M. Nurul Islam M. Baquer Chandrakant S. Pandav Harun K. M. Yusuf 《Indian journal of clinical biochemistry : IJCB》1997,12(2):128-133
Urinary iodine levels in children (5–11 years) and in adult males and females (15–44 years) of three ecological zones (hilly, flood-prone and plains) of Bangladesh were analyzed to determine the status of biochemical iodine deficiency in the country. Data indicated that a large majority of the population all over Bangladesh have biochemical iodine deficiency urinary iodine excretion (UIE) less than the accepted cut-off level of 10 μg/dl. Adults were deficient to comparable degrees, 31.3% severely iodine deficient. The flood-prone zone was less affected: 71.7% children had iodine deficiency and 25% were severely deficient. Adults of this zone were less affected than the children. Iodine deficiency was least severe in the plain zone: 59.8% children were biochemically iodine deficient and of them 23.4% had UIE less than 2.0 μg/dl. In the case of the adults of this zone, 60.8% were biochemically iodine deficient and 20.6% had severe iodine deficiency. The results indicate that Bangladesh as a whole is an iodine deficient region, with the hilly zone being the most severely affected. Children were slightly more affected than the adults, and females were more affected than the males. 相似文献
13.
Real options analysis was often recommended as an emerging valuation technique for high-risk investment projects. Former inter-sectoral surveys have drawn an ambivalent picture of real options usage in general. In addition, there is a lack of sector-specific investigations. In the following article the results of an in-depth analysis of collected empirical data regarding the application of this new tool in the pharmaceutical sector is presented by capturing the internal view from the pharmaceutical companies themselves and the external view from the health care departments of financial service firms. R&D stage specific modi of application, reasons for reluctance in the employment of real options and their assumed future prospects are elucidated. 相似文献
14.
Islam MR Khandoker MA Afroz S Rahman MG Khan RI 《Journal of Zhejiang University. Science. B》2007,8(7):465-469
Goat ovaries were collected from the slaughterhouse and categorized as right, left, corpus luteum (CL)-present and -absent group and evaluated on the basis of weight (g), length (cm), width (cm), number of follicles, follicles aspirated and number and state ofcumulus-oocyte-complexes (COCs). Comparatively higher weight [(0.66±0.02) vs (0.64±0.02) g], length [(1.17±0.02) vs (1.1 ±0.02) cm] and width [(0.77±0.02) vs (0.74±0.02) cm] were found in right ovaries than those of left. On the other hand significantly (P〈0.05) higher weight [(0.71±0.03) vs (0.64±0.01) g] and width [(0.76±0.03) vs (0.75±0.01) cm] were found in CL-present group than those of CL-absent group of ovaries. The left ovaries contained comparatively higher number of normal COCs [(1.06±0.09) per ovary] than fight ovaries [(1.03±0.10) per ovary] and the similar trend was found in total number of follicles [(4.51±0.25) vs (4.30±0.23) per ovary] and follicles aspirated [(2.55±0.14) vs (2.52±0.12) per ovary]. But the total COCs per ovary was almost similar in both ovaries [right and left: (1.85±0.12) and (1.85±0.11) per ovary, respectively]. Higher number of total COCs [(1.87±0.09) vs (1.76±0.16) per ovary], total number of follicles [(4.45±0.19) vs (4.16±0.37) per ovary], follicles aspirated [(2.55±0.10) vs (2.48±0.21) per ovary] and normal COCs [(1.12±0.07) vs (0.76±0.14) per ovary] were found in CL-absent group than those of CL-present group of ovaries. 相似文献
15.
Dong-Dong Wu Cui-Ping Yang Ming-Shan Wang Kun-Zhe Dong Da-Wei Yan Zi-Qian Hao Song-Qing Fan Shu-Zhou Chu Qiu-Shuo Shen Li-Ping Jiang Yan Li Lin Zeng He-Qun Liu Hai-Bing Xie Yun-Fei Ma Xiao-Yan Kong Shu-Li Yang Xin-Xing Dong Ali Esmailizadeh David M Irwin Xiao Xiao Ming Li Yang Dong Wen Wang Peng Shi Hai-Peng Li Yue-Hui Ma Xiao Gou Yong-Bin Chen Ya-Ping Zhang 《国家科学评论(英文版)》2020,7(6):952
Abundant and diverse domestic mammals living on the Tibetan Plateau provide useful materials for investigating adaptive evolution and genetic convergence. Here, we used 327 genomes from horses, sheep, goats, cattle, pigs and dogs living at both high and low altitudes, including 73 genomes generated for this study, to disentangle the genetic mechanisms underlying local adaptation of domestic mammals. Although molecular convergence is comparatively rare at the DNA sequence level, we found convergent signature of positive selection at the gene level, particularly the EPAS1 gene in these Tibetan domestic mammals. We also reported a potential function in response to hypoxia for the gene C10orf67, which underwent positive selection in three of the domestic mammals. Our data provide an insight into adaptive evolution of high-altitude domestic mammals, and should facilitate the search for additional novel genes involved in the hypoxia response pathway. 相似文献
16.
Sajjad Rahmani Dabbagh Fazle Rabbi Zafer Doan Ali Kemal Yetisen Savas Tasoglu 《Biomicrofluidics》2020,14(6)
High-throughput, cost-effective, and portable devices can enhance the performance of point-of-care tests. Such devices are able to acquire images from samples at a high rate in combination with microfluidic chips in point-of-care applications. However, interpreting and analyzing the large amount of acquired data is not only a labor-intensive and time-consuming process, but also prone to the bias of the user and low accuracy. Integrating machine learning (ML) with the image acquisition capability of smartphones as well as increasing computing power could address the need for high-throughput, accurate, and automatized detection, data processing, and quantification of results. Here, ML-supported diagnostic technologies are presented. These technologies include quantification of colorimetric tests, classification of biological samples (cells and sperms), soft sensors, assay type detection, and recognition of the fluid properties. Challenges regarding the implementation of ML methods, including the required number of data points, image acquisition prerequisites, and execution of data-limited experiments are also discussed. 相似文献
17.
Ali Asghar Ghasemi Hooshang Yazdani Majid Amerian 《Journal of Intercultural Communication Research》2020,49(1):41-60
ABSTRACTThis study aimed to present a model of intercultural communicative competence (ICC) by incorporating international posture, motivational disposition (ideal L2 self), second language (L2) self-confidence, and metacognitive learning strategies. To this end, 150 Iranian L2 learners, selected through convenience sampling procedure, took part in the research. The findings of structural equation modelling revealed that the proposed model showed adequate fit to the data, implying that the model is appropriate in Iranian English as a foreign language (EFL) context. Also, the results indicated that learners with a high level of international posture are more likely to bridge the gap between their present and ideal selves. This was, additionally, argued that internationally oriented and ideally motivated learners become confident of their abilities to get engaged in interaction with L2 target communities. Furthermore, metacognitive learning strategies were found to be directly associated with ICC, implicating that the learners who continuously reflect on their learning and evaluate their performances are more prone to have a higher level of ICC. Finally, suggestions were offered for language teachers and policy-makers to inspire their learners to be more competent in communication with people of other cultures and languages. 相似文献
18.
Robert Dan Michael Cate A. Egan Lynda Nilges Ali Brian Robert Johnson 《Research quarterly for exercise and sport》2019,90(2):151-162
Purpose: A systematic review was conducted to identify facilitators and barriers to movement integration (MI) in elementary school classrooms. Method: Online databases (Educational Resources Information Center, Google Scholar, PsycINFO, and PubMed) served as data sources for the study. Following the PRISMA guidelines, relevant published research on MI was identified and screened for inclusion in a qualitative synthesis. Content analysis of the included articles (N = 28) was used to identify themes of MI facilitators and barriers. Facilitators and barriers were then categorized using a social-ecological framework. Results: A total of 12 themes of MI facilitators and barriers were identified and categorized into two social-ecological levels: institutional factors (e.g., administrative support, resources) and intrapersonal factors (e.g., teacher confidence, ease of implementation). Conclusion: This review can inform research and practice aimed at supporting the implementation of MI in elementary classrooms. 相似文献
19.
20.
Fatma Emel Kocak Bahadir Ozturk Ozben Ozden Isiklar Ozlem Genc Ali Unlu Irfan Altuntas 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2015,25(3):430-438