全文获取类型
收费全文 | 24255篇 |
免费 | 199篇 |
国内免费 | 21篇 |
专业分类
教育 | 17420篇 |
科学研究 | 2062篇 |
各国文化 | 221篇 |
体育 | 1791篇 |
综合类 | 34篇 |
文化理论 | 201篇 |
信息传播 | 2746篇 |
出版年
2022年 | 166篇 |
2021年 | 251篇 |
2020年 | 433篇 |
2019年 | 555篇 |
2018年 | 764篇 |
2017年 | 850篇 |
2016年 | 796篇 |
2015年 | 474篇 |
2014年 | 632篇 |
2013年 | 4594篇 |
2012年 | 614篇 |
2011年 | 670篇 |
2010年 | 515篇 |
2009年 | 481篇 |
2008年 | 555篇 |
2007年 | 533篇 |
2006年 | 465篇 |
2005年 | 419篇 |
2004年 | 387篇 |
2003年 | 350篇 |
2002年 | 402篇 |
2001年 | 430篇 |
2000年 | 405篇 |
1999年 | 411篇 |
1998年 | 226篇 |
1997年 | 237篇 |
1996年 | 267篇 |
1995年 | 222篇 |
1994年 | 215篇 |
1993年 | 199篇 |
1992年 | 315篇 |
1991年 | 309篇 |
1990年 | 344篇 |
1989年 | 317篇 |
1988年 | 303篇 |
1987年 | 257篇 |
1986年 | 259篇 |
1985年 | 331篇 |
1984年 | 270篇 |
1983年 | 262篇 |
1982年 | 198篇 |
1981年 | 215篇 |
1980年 | 179篇 |
1979年 | 250篇 |
1978年 | 220篇 |
1977年 | 204篇 |
1976年 | 166篇 |
1975年 | 129篇 |
1974年 | 125篇 |
1973年 | 150篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
981.
Mohammed A. El-Magd Ayman A. Saleh Abeer A. Nafeaa Shymaa M. El-Komy Mohamed A. Afifi 《Journal of Zhejiang University. Science. B》2017,18(12):1064-1074
The insulin-like growth factor 1 (IGF1) gene is a member of the group of somatotropin axis genes that play a significant role in cell proliferation and growth of muscles. Here, we searched for polymorphisms in buffalo IGF1 and found two novel single nucleotide polymorphisms (SNPs), G64A and G280A, in the noncoding sequences of exon 1 and exon 4, respectively. Statistical analysis of different genotypes showed that the individuals with GG genotypes had significantly (P<0.05) higher body weight (BW) and average daily gain (ADG) than those with other genotypes at ages of 3–6 months in G64A SNP and 6–9 months in G280A SNP. The combined genotypes of these two SNPs produced three haplotypes, GG/GG, AG/AG, and AA/AA, which were significantly associated (P<0.0001) with BW and ADG at an age from 3 to 12 months. Buffaloes with the homozygous GG/GG haplotype showed higher growth performance than other buffaloes. The two SNPs were correlated with mRNA levels of IGF1 and IGF1 receptor (IGF1R) in semitendinosus muscle as well as with the serum concentration level of IGF1. Also, buffaloes with GG/GG haplotype showed higher mRNA and serum concentration levels. The data revealed that these two SNPs could be valuable genetic markers for selection of Egyptian buffaloes for better performance in the population. 相似文献
982.
983.
Serum free fatty acids (FFA) in 100 parturient (50 primiparous and 50 multiparous volunteers) and 50 female patient (30 patients 20–30 years age group and 20 patients 31–50 yrs age group) volunteers undergoing elective major abdominal surgery were monitored during different stages of delivery and surgery respectively. FFA increased in both primiparous and multiparous from full term (46 mg%) to second stage of labour (60 mg%) and gradually decreased to 38 mg% on the third day postpartum. The intergroup comparison between primiparous and multiparous was significant. Surgical stress also increased FFA from the day of admission (21 mg%) to the preoperative stage (35 mg%). The intergroup comparison between 20–30 yrs age group and 31–50 yrs age group did not show any significant change. 相似文献
984.
985.
E. K. H. Saitta M. A. Bowdon C. L. Geiger 《Journal of Science Education and Technology》2011,20(6):790-795
Technology was integrated into service-learning activities to create an interactive teaching method for undergraduate students
at a large research institution. Chemistry students at the University of Central Florida partnered with high school students
at Crooms Academy of Information Technology in interactive service learning projects. The projects allowed UCF students to
teach newly acquired content knowledge and build upon course lecture and lab exercises. Activities utilized the web-conferencing
tool Adobe Connect Pro to enable interaction with high school students, many of whom have limited access to supplemental educational
opportunities due to low socioeconomic status. Seventy chemistry I students created lessons to clarify high school students’
misconceptions through the use of refutational texts. In addition, 21 UCF students enrolled in the chemistry II laboratory
course acted as virtual lab partners with Crooms students in an interactive guided inquiry experiment focused on chemical
kinetics. An overview of project’s design, implementation, and assessments are detailed in the case study and serve as a model
for future community partnerships. Emerging technologies are emphasized as well as a suggested set of best practices for future
projects. 相似文献
986.
Transforming the College through Technology: A Change of Culture 总被引:1,自引:0,他引:1
James A. McLoughlin Lih-Ching Chen Wang William A. Beasley 《Innovative Higher Education》2008,33(2):99-109
In this article we address the implementation of sustainable technological change among the faculty, staff, and students in the College of Education and Human Services at a mid-western urban institution. We examine cultural factors common to institutions of higher education and then describe particular planning and implementation processes employed at one institution to move faculty and staff from a state of minimal technology use to one of substantial technological competence over a period of years. The process turns out to be robust and stable despite growth over time. We conclude with recommendations for other educational institutions facing similar needs for cultural change in the use of technology. James A. McLoughlin has been Dean of the College of Education and Human Services at Cleveland State University since 1995 and Interim Provost from 2000 to 2001; he received his Ph.D. in Special Education from the University of Arizona. Lih-Ching Chen Wang is a Fulbright Scholar. She is currently an Associate Professor of Education in the Department of Curriculum and Foundations at Cleveland State University. Her work focuses on the integration of technology into teacher education. She holds a Ph.D. in Instructional Technology from Kent State University. William A. Beasley is a Professor of Education who specializes in Educational Technology and runs the Center for Teaching Excellence at Cleveland State University. He holds an Ed. D. in Gifted Education from the University of Georgia. 相似文献
987.
988.
989.
Alexandra LaLonde Maria F. Romero-Creel Mario A. Saucedo-Espinosa Blanca H. Lapizco-Encinas 《Biomicrofluidics》2015,9(6)
Isolation and enrichment of low-abundant particles are essential steps in many bio-analytical and clinical applications. In this work, the capability of an insulator-based dielectrophoresis (iDEP) device for the detection and stable capture of low abundant polystyrene particles and yeast cells was evaluated. Binary and tertiary mixtures of particles and cells were tested, where the low-abundant particles had concentration ratios on the order of 1:10 000 000 compared to the other particles present in the mixture. The results demonstrated successful and stable capture and enrichment of rare particles and cells (trapping efficiencies over 99%), where particles remained trapped in a stable manner for up to 4 min. A device with four reservoirs was employed for the separation and enrichment of rare particles, where the particles of interest were first selectively concentrated and then effectively directed to a side port for future collection and analysis. The present study demonstrates that simple iDEP devices have appropriate screening capacity and can be used for handling samples containing rare particles; achieving both enrichment and isolation of low-abundant particles and cells. 相似文献
990.
This study seeks to analyze how students apply a mathematical modeling skill that was previously learned by solving standard word problems to the solution of word problems with nonstandard contexts. During the course of an experiment involving 106 freshmen, we assessed how well they were able to transfer the mathematical modeling skill that is used to solve standard problems to the solution of nonstandard ones that had an analogous structure. The results of our research show that students had varying degrees of success applying the different stages of modeling depending on whether they were solving a familiar problem (involving near transfer) or one that had an unfamiliar context (involving far transfer): in cases of near transfer, students applied the template formally even though it did not align with the text of the new word problem, which complicated further interpretation. In cases of far transfer, students chose to solve the problem by using an ordinary method of selecting a solution by trial and error in preference to the use of modeling. Thus, the application of the modeling skill as a multistage process is complicated when solving nonstandard problems involving either near or far transfer. 相似文献