全文获取类型
收费全文 | 1854篇 |
免费 | 22篇 |
国内免费 | 12篇 |
专业分类
教育 | 1025篇 |
科学研究 | 286篇 |
各国文化 | 6篇 |
体育 | 347篇 |
综合类 | 24篇 |
文化理论 | 2篇 |
信息传播 | 198篇 |
出版年
2023年 | 15篇 |
2022年 | 16篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2016年 | 7篇 |
2015年 | 7篇 |
2014年 | 26篇 |
2013年 | 29篇 |
2012年 | 150篇 |
2011年 | 212篇 |
2010年 | 83篇 |
2009年 | 20篇 |
2008年 | 113篇 |
2007年 | 141篇 |
2006年 | 119篇 |
2005年 | 113篇 |
2004年 | 94篇 |
2003年 | 100篇 |
2002年 | 88篇 |
2001年 | 48篇 |
2000年 | 67篇 |
1999年 | 50篇 |
1998年 | 12篇 |
1997年 | 19篇 |
1996年 | 14篇 |
1995年 | 24篇 |
1994年 | 14篇 |
1993年 | 22篇 |
1992年 | 23篇 |
1991年 | 22篇 |
1990年 | 23篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 17篇 |
1986年 | 17篇 |
1985年 | 15篇 |
1984年 | 12篇 |
1983年 | 19篇 |
1982年 | 9篇 |
1981年 | 16篇 |
1980年 | 8篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1958年 | 3篇 |
1957年 | 3篇 |
1948年 | 3篇 |
1937年 | 3篇 |
1927年 | 3篇 |
排序方式: 共有1888条查询结果,搜索用时 15 毫秒
31.
The nature and correlates of underachievement among elementary schoolchildren in Hong Kong 总被引:2,自引:0,他引:2
This study investigated for the first time several characteristics of underachievement in a large sample of Hong Kong elementary schoolchildren. More males were identified as underachievers than females, but the ratio was substantially less than the two-to-one rate typically found in the American literature. The stability and persistence of underachievement increased during the elementary school years, and the stability of underachievement tended to be higher in subject matter that was relatively more difficult, which varied with gender. Underachievement became more specific to particular academic subjects rather than more general across the elementary grades. Parents and teachers, but not the children themselves, perceived that underachievers were more capable than same-grade nonunderachievers (who score lower on ability tests), although this awareness is more likely directed at male than female underachievers, which has been observed in other samples. In grades 1-4, teachers provided extra mentoring, communications, and support to underachievers. Thereafter, underachievers became more disruptive, impatient, and aggressive in school and perhaps at home. At that point, teachers became less supportive, offered less extra mentoring, and applied greater behavioral control over underachievers. Underachieving children also perceived that their parents became less supportive and used more discipline in grades 5-6 relative to grades 3-4. These correlates of underachievement suggests the existence of a syndrome of underachievement that separates underachievers from children who have the same grades but lower mental ability. 相似文献
32.
S.M.Ishtiaque 《技术创新》2004,(11):24-27
织物风格特征是由织物组织结构和纱的特性决定的,新型纱线结构的不断出现和发展对织物性能和质量提出了更高的要求。研究表明:通过改变纺纱工艺可以获得不同的纱线结构,从而改变织物的风格特征。DREF-Ⅲ型摩擦纺包芯纱具有典型的皮芯结构,可以是双组分也可以是多组分,而且组分的不同会对织物性能产生不同的影响,纱的性能也会由于芯皮之间压力、摩擦力大小的不同而改变。以前的研究主要集中在包芯纱的拉伸性能上,而对空心纱几乎没有什么新的研究和讨论。 相似文献
33.
OBJECTIVES: To investigate whether an information literacy programme for pre-registration nursing students at a UK higher education institution is effective in developing their skills and confidence: examines students' skill levels, factors affecting their confidence, and relationships between skills, confidence and demographic characteristics. METHODS: Quantitative and qualitative techniques were used: pre- and post-tests to measure changes in students' skills and self-assessed confidence levels after two key sessions in their first semester (n = 29); semi-structured interviews to explore factors affecting confidence (n = 5). RESULTS: Findings demonstrated positive impacts on skills and confidence. Key areas of skill development included: identifying journal articles, selecting search terms and evaluating website quality. Factors affecting confidence included: successful 'mastery' experiences in searching for information and the programme itself, especially small-group sessions, handouts and staff support. Evidence on links between skills, confidence and demographic factors was inconclusive. CONCLUSIONS: The study demonstrated the programme's effectiveness and identified areas for development, including the need to help students understand the relative merits of search engines and other sources. Evidence has contributed to a change in departmental policy, making attendance at sessions mandatory. Further studies have been recommended. 相似文献
34.
Jackson R Baird W Davis-Reynolds L Smith C Blackburn S Allsebrook J 《Health information and libraries journal》2007,24(2):95-102
OBJECTIVES: The objectives of this work were to identify the sources of information currently received, information-seeking behaviours, information requirements and preferences for future information provision amongst health and social care professionals providing care to children with health care needs. METHODS: Data were collected using a cross-sectional postal questionnaire survey. RESULTS: A wide range of information resources was reported as being available to professionals. However, a large proportion of respondents found it necessary to perform additional searches for information, suggesting that current resources were not satisfying their needs. The majority of professionals reported a preference for electronic formats, whilst a smaller proportion preferred hard copy materials. Participants promoted the use of informal networks as a means of support and exchange of information. CONCLUSION: Supplementing the information that is provided in electronic and hard copy formats, by enhancing informal networks, may be the most effective way of meeting the information needs of this group of professionals. 相似文献
35.
Berent GP Kelly RR Aldersley S Schmitz KL Khalsa BK Panara J Keenan S 《Journal of deaf studies and deaf education》2007,12(1):8-24
Focus-on-form English teaching methods are designed to facilitate second-language learners' noticing of target language input, where "noticing" is an acquisitional prerequisite for the comprehension, processing, and eventual integration of new grammatical knowledge. While primarily designed for teaching hearing second-language learners, many focus-on-form methods lend themselves to visual presentation. This article reports the results of classroom research on the visually based implementation of focus-on-form methods with deaf college students learning English. Two of 3 groups of deaf students received focus-on-form instruction during a 10-week remedial grammar course; a third control group received grammatical instruction that did not involve focus-on-form methods. The 2 experimental groups exhibited significantly greater improvement in English grammatical knowledge relative to the control group. These results validate the efficacy of visually based focus-on-form English instruction for deaf students of English and set the stage for the continual search for innovative and effective English teaching methodologies. 相似文献
36.
37.
A consumer advocate, two childbirth educators, and a certified nurse-midwife each provide commentary on the effectiveness of and potential uses for the Evidence Basis for the Ten Steps of Mother-Friendly Care. 相似文献
38.
Shalini M Yogeeswari P Sriram D Induja S 《Journal of Zhejiang University. Science. B》2007,8(1):45-55
Objective: To study the effect of halo substitution on disubstituted aryl semicarbazones on the anticonvulsant potential and model the activity based on quantum mechanics. Methods: A series of twenty-six compounds of N^4-(4-bromo-3-methylphenyl) semicarbazones were synthesized and evaluated for the anticonvulsant activity in the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure threshold tests. Some potential compounds were also tested in the subcutaneous strychnine (scSTY) and subcutaneous picrotoxin (scPIC) seizure threshold tests. The synthesized compounds were tested for behavioral impairment and CNS (central nervous system) depression in mice. Quantum mechanical modelling was carried out on these compounds to gain understanding on the structural features essential for activity. Results: Some compounds possessed broad spectrum anticonvulsant activity as indicated by their effect in pentylenetetrazole, strychnine, picrotoxin and maximal electroshock seizures models in resemblance to other aryl semicarbazone derivatives reported earlier. The higher the difference in HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy levels was, the greater was the activity profile. Conclusion: The pharmacophoric requirements for compounds to exhibit anticonvulsant activity that includes one aryl unit in proximity to a hydrogen donor-acceptor domain and an electron donor have been justified with the molecular orbital surface analysis of the synthesized compounds. 相似文献
39.
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
40.
Genetic analysis of fruit shape traits at different maturation stages in sponge gourd 总被引:5,自引:0,他引:5
The fruit shape is important quantitative trait closely related to the fruit quality. However, the genetic model of fruit shapes has not been proposed. Therefore, in the present study, analysis of genetic effects for fruit shape traits (fruit length and fruit perimeter) in sponge gourd was conducted by employing a developmental genetic model including fruit direct effects and maternal effects. Analysis approaches of unconditional and conditional variances were applied to evaluate the genetic behavior of fruit shape traits at economical and physiological maturation times. The results of variance analysis indicated that fruit length and fruit perimeter were simultaneously affected by fruit direct genetic effects and maternal effects. Fruit direct genetic effects were relatively more important for fruit shape traits at whole developmental period. The gene expression was most active at the economical maturation stage (1-12 d after flowering) for two shape traits, and the activation of gene was mostly due to direct dominance effects at physiological maturation stage (13-60 datter flowering). The coefficients due to different genetic effects, as well as the phenotypic correlation coefficients, varied significantly between fruit shape traits themselves at various maturation stages. The results showed that it was relatively easy to improve fruit shape traits for industrial purpose by carefully selecting the parents at economical maturation stage instead of that at physiological maturation stage. 相似文献