全文获取类型
收费全文 | 205篇 |
免费 | 7篇 |
专业分类
教育 | 178篇 |
科学研究 | 9篇 |
各国文化 | 2篇 |
体育 | 9篇 |
文化理论 | 2篇 |
信息传播 | 12篇 |
出版年
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 7篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 10篇 |
2013年 | 45篇 |
2012年 | 2篇 |
2011年 | 9篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 4篇 |
1967年 | 2篇 |
1964年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有212条查询结果,搜索用时 82 毫秒
1.
Shoudong Wang Shulin Liu Jie Wang Kengo Yokosho Bin Zhou Ya-Chi Yu Zhi Liu Wolf B Frommer Jian Feng Ma Li-Qing Chen Yuefeng Guan Huixia Shou Zhixi Tian 《国家科学评论(英文版)》2020,7(11):1776
Soybean accounts for more than half of the global production of oilseed and more than a quarter of the protein used globally for human food and animal feed. Soybean domestication involved parallel increases in seed size and oil content, and a concomitant decrease in protein content. However, science has not yet discovered whether these effects were due to selective pressure on a single gene or multiple genes. Here, re-sequencing data from >800 genotypes revealed a strong selection during soybean domestication on GmSWEET10a. The selection of GmSWEET10a conferred simultaneous increases in soybean-seed size and oil content as well as a reduction in the protein content. The result was validated using both near-isogenic lines carrying substitution of haplotype chromosomal segments and transgenic soybeans. Moreover, GmSWEET10b was found to be functionally redundant with its homologue GmSWEET10a and to be undergoing selection in current breeding, leading the the elite allele GmSWEET10b, a potential target for present-day soybean breeding. Both GmSWEET10a and GmSWEET10b were shown to transport sucrose and hexose, contributing to sugar allocation from seed coat to embryo, which consequently determines oil and protein contents and seed size in soybean. We conclude that past selection of optimal GmSWEET10a alleles drove the initial domestication of multiple soybean-seed traits and that targeted selection of the elite allele GmSWEET10b may further improve the yield and seed quality of modern soybean cultivars. 相似文献
2.
3.
This study examines how parent socioeconomic status (SES) directly and indirectly predicts children's school readiness through pathways of parental investment. Data come from direct assessments with preschool children and surveys with their primary caregivers in Ghana at the start of the 2015–2016 school year (N = 2,137; Mage = 5.2 years). Results revealed SES-related gaps in all parental investment characteristics and child school readiness skills. Preschool involvement served as the primary mediating mechanism in the path from SES to most school readiness skills, though it did not predict executive function. The number of books in the household was marginally positively predictive of early literacy, whereas at-home stimulation was negatively related to motor, literacy, and numeracy skills. 相似文献
4.
5.
6.
Arne Frick Rainer Neumann und Wolf Zimmermann 《Informatik - Forschung und Entwicklung》1997,12(4):186-195
Zusammenfassung. In diesem Beitrag wird eine Methode zur Konstruktion robuster Klassenhierarchien vorgestellt. Hierzu wird aus den überlegungen
bezüglich der polymorphen Verwendung von Klassen [2] eine Vorgehensweise zur Konstruktion von Klassenhierarchien abgeleitet.
Die Begriffe Konformit?t und Spezialisierung werden verfeinert, indem nicht mehr s?mtliche Methoden einer Klasse, sondern
Teilmengen davon betrachtet werden. Dies führt zum Begriff der partiellen Konformit?t. In Erweiterung von [2] sind partiell konforme Klassen dann polymorph verwendbar, wenn der Anwendungskontext, der sich aus der Benutzung der Klasse ergibt, sich ausschlie?lich auf konforme Methoden erstreckt. Diese Eigenschaft ist
statisch zur übersetzungszeit überprüfbar. Damit k?nnen Fehlbenutzungen bereits zur übersetzungszeit ausgeschlossen werden.
Eingegangen am 24. Dezember 1996 / Angenommen am 15. Oktober 1997 相似文献
7.
8.
A. Zaher S. Li K. T. Wolf F. N. Pirmoradi O. Yassine L. Lin N. M. Khashab J. Kosel 《Biomicrofluidics》2015,9(5)
Implantable drug delivery systems can provide long-term reliability, controllability, and biocompatibility, and have been used in many applications, including cancer pain and non-malignant pain treatment. However, many of the available systems are limited to zero-order, inconsistent, or single burst event drug release. To address these limitations, we demonstrate prototypes of a remotely operated drug delivery device that offers controllability of drug release profiles, using osmotic pumping as a pressure source and magnetically triggered membranes as switchable on-demand valves. The membranes are made of either ethyl cellulose, or the proposed stronger cellulose acetate polymer, mixed with thermosensitive poly(N-isopropylacrylamide) hydrogel and superparamagnetic iron oxide particles. The prototype devices'' drug diffusion rates are on the order of 0.5–2 μg/h for higher release rate designs, and 12–40 ng/h for lower release rates, with maximum release ratios of 4.2 and 3.2, respectively. The devices exhibit increased drug delivery rates with higher osmotic pumping rates or with magnetically increased membrane porosity. Furthermore, by vapor deposition of a cyanoacrylate layer, a drastic reduction of the drug delivery rate from micrograms down to tens of nanograms per hour is achieved. By utilizing magnetic membranes as the valve-control mechanism, triggered remotely by means of induction heating, the demonstrated drug delivery devices benefit from having the power source external to the system, eliminating the need for a battery. These designs multiply the potential approaches towards increasing the on-demand controllability and customizability of drug delivery profiles in the expanding field of implantable drug delivery systems, with the future possibility of remotely controlling the pressure source. 相似文献
9.
Pedro Rosário José Carlos Núñez Luisa Trigo Carina Guimarães Estrella Fernández Rebeca Cerezo 《高等教育研究与发展》2015,34(1):173-187
The current investigation aims at assessing the effectiveness of an intervention program designed to enhance self-regulated learning (SRL) strategies at the university level, with students from different cultural, linguistic, and educational backgrounds. The central tool of the program is a set of letters in which a fictional first-year student describes his experiences as an SRL student. The program was implemented in four universities in different countries and continents (Portugal, Spain, Chile, and Mozambique), with an experimental group and a comparison group at each university (263 students from experimental groups and 247 from comparison groups). Findings display the effectiveness of the program in enhancing a set of motivational variables related to the study process and the use of SRL strategies. Data were consistent across the different cultural and academic contexts in which the program was implemented. The implications of these findings for university administrators and faculty are discussed. 相似文献
10.
Shereen C. Naser Katherine Clonan-Roy Kimberly A. Fuller Elizabeth A. Goncy Nicole Wolf 《Psychology in the schools》2022,59(1):34-50
The purpose of this study is to describe the experiences of lesbian, gay, bisexual, transgender, questioning, intersex, two spirit, and queer (LGBTQ+) youth with school-based sexuality education (SBSE), as well as to document strategies LGBTQ+ youth are using to address their evolving and specific sexual health needs outside of SBSE. Researchers conducted focus groups with 17 adolescents (ages 14–18) from urban and suburban Midwestern cities. Results of this study indicate LGBTQ+ youth find SBSE to be heteronormative, cisgender focused, and primarily focused on pregnancy and disease prevention, which contributes to LGBTQ+ youth experiences of exclusion. In response to SBSE that did not meet student needs, participants reported seeking sexual health information outside of SBSE. Other sources included family and other trusted adults, the Internet, and community resource centers. Students reported variable rates of use and trustworthiness across these resources. Results of this study suggest that school personnel should consider alternatives to traditional SBSE models to meet the needs of LGBTQ+ youth, and that an important part of SBSE should include guidelines for Internet safety. 相似文献