首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   16477篇
  免费   176篇
  国内免费   30篇
教育   11098篇
科学研究   2102篇
各国文化   169篇
体育   1246篇
综合类   10篇
文化理论   122篇
信息传播   1936篇
  2021年   119篇
  2020年   202篇
  2019年   305篇
  2018年   346篇
  2017年   399篇
  2016年   357篇
  2015年   238篇
  2014年   349篇
  2013年   3073篇
  2012年   328篇
  2011年   324篇
  2010年   286篇
  2009年   289篇
  2008年   354篇
  2007年   332篇
  2006年   304篇
  2005年   268篇
  2004年   228篇
  2003年   211篇
  2002年   215篇
  2001年   242篇
  2000年   283篇
  1999年   244篇
  1998年   139篇
  1997年   130篇
  1996年   155篇
  1995年   136篇
  1994年   156篇
  1993年   159篇
  1992年   244篇
  1991年   234篇
  1990年   226篇
  1989年   259篇
  1988年   196篇
  1987年   207篇
  1986年   216篇
  1985年   246篇
  1984年   223篇
  1983年   215篇
  1982年   190篇
  1981年   176篇
  1980年   166篇
  1979年   212篇
  1978年   222篇
  1977年   162篇
  1976年   164篇
  1975年   129篇
  1974年   127篇
  1973年   141篇
  1972年   112篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
971.
Maximal voluntary static muscle force production was assessed both in strength trials and during 2-min contractions by three muscle groups (right-hand finger flexors [RHF], right-leg extensors [RLE], and both leg extensors [BLE]) in young males (n = 13) and females (n = 14). There was a significant difference (p less than .01) between males and females for RHF strength and BLE strength but no significant difference between sexes for RLE strength. During the 2-min task, impulse (force x time) declined significantly (p less than .001) and there was a significant difference (p less than .001) between muscle groups, but there was no difference between sexes. There was a significant (p less than .05) sex x time interaction for the impulse values indicating that the fatigability was greater in males than females.  相似文献   
972.
Tumor lysis syndrome has been observed in patients with malignancies with high cellular burden and high cell turnover, tumor sensitive to therapy, especially after initiating medical treatment. It very rarely occurs spontaneously. The case described here is of 6 months male infant who presented with fever since 1 month and loose stools associated with blood since 15 days. The laboratory investigations showed lactate dehydrogenase (LDH) of 6,192 IU/L and serum uric acid 18.2 mg/dl along with pancytopenia. The infant presented with electrolyte abnormalities and renal failure.  相似文献   
973.
The present work was aimed to study the association of one carbon genetic variants, hyperhomocysteinemia and oxidative stress markers, i.e., serum nitrite, plasma malondialdehyde (MDA) and glutathione (GSH) on intimal medial thickening (IMT) in patients with type 2 diabetes mellitus (T2D). A total number of 76 subjects from ACS Medical College and Hospital, Chennai, India were included in the study, i.e., Group I (n = 42) of T2D and Group II (n = 34) of age- and sex matched healthy controls. The glycated haemoglobin was measured by ion-exchange resin method; plasma homocysteine by Enzyme Linked Immunosorbant Assay method; serum nitrite (nitric oxide, NO), plasma MDA and GSH by spectrophotometric methods; the IMT by high frequency ultrasound. The polymorphisms of one carbon genetic variants were genotyped using polymerase chain reaction-restriction fragment length polymorphism and amplified fragment length polymorphism methods. Results indicate that methyltetrahydrofolate homocysteine methyl transferase (MTR) A2756G allele was found to be protective in T2D and the other variants were not significantly associated with T2D. Glutamate carboxypeptidase II (GCP II) C1561T (r = 0.34; p = 0.05) and methylene tetrahydrofolate reductase (MTHFR) C677T (r = 0.35; 0.04) showed positive correlation with plasma homocysteine in T2D cases. In this study, MTR A2756G allele was found to be protective in T2D; GCP II C1561T and MTHFR C677T showed positive association with plasma homocysteine in T2D cases. Among all the genetic variants, MTR A2756G was found influence IMT. RFC 1 G80A and TYMS 5′-UTR 2R3R showed synergistically interact with MTR A2756G in influencing increase in IMT.  相似文献   
974.
Although many newly-graduated librarians are applying for and accepting part-time library employment after graduation, little research has been done into what working part-time means for these early career librarians. This article, based on a survey of recent LIS graduates who have worked part-time, provides a snapshot of part-time library employment and the advantages and disadvantages it affords to new librarians. This information is particularly relevant in light of the difficult job market for entry-level librarians. All of the surveyed librarians have worked in at least one part-time professional or paraprofessional position in a library after receiving their degree. Many of these respondents describe holding multiple part-time positions and receiving low salaries and few, if any, employment benefits. The themes documented in the open-ended short answers of these part-time librarians will help to guide further research into the professional and personal impact of part-time employment.  相似文献   
975.
This paper reports the conclusions and recommendations of the working group that synthesized the discussions on ‘How can science connect with and be of greater benefit to conservation practice?’ during the ICCROM Forum on Conservation Science. The author reflects on these findings from her own perspective and experiences, and places them in the context of two major shifts in heritage research: the first, a shift in focus from conserving materials to managing meaning. The second, a shift in organizational structures from single, centrally funded heritage institutions towards diffuse networks which include new players who have no direct responsibility towards heritage. Both shifts are taking place in an environment of decreased funding and increased accountability to society. Science and conservation connect and contribute to each other most effectively if they together contribute to the societal benefits of heritage. In this regard, heritage science strategies can stimulate collaboration, and direct science and conservation towards innovative, applicable outcomes. Moreover, they can promote a transdisciplinary approach which connects social, economic and business sciences and stakeholders. They should also ensure the creation of sustainable nodes for consolidating knowledge within these dynamic networks.  相似文献   
976.
The experience from the application of the OKVED 2 economic classifier for indexing scientific publications is considered. More than 9500 articles on the subject of “Automation. Computer Engineering” in authoritative Russian magazines were the material for the study. Some means for the comparative analysis of economic statistics and results of the classification of scientific publications are shown.  相似文献   
977.
Recent research has shown that exposure to entertainment media depicting moral beauty may not only influence viewers' affective responses, but also lead to altruistic behavior. Although the process has been tied to a set of feelings commonly referred to as elevation, the mechanisms by which the effects take place have not been examined. This experiment (N = 107) showed that participants who watched a clip portraying moral beauty were more likely to help with an unrelated volunteer task after viewing than those who watched a non-meaningful clip. The effect of the clip was mediated by the degree to which the clip produced mixed affective response in participants. Although the clip portraying moral beauty led to increased empathy with the character and increased feelings of elevation, neither of these predicted helping behavior after controlling for clip content. Helping behavior also increased when the help recipient was less similar to the participants (age, race, and university affiliation).  相似文献   
978.
This study investigated whether anticipation and search strategies of goalkeepers are influenced by temporally and spatially manipulated video of a penalty. Participants were clustered into three groups depending on skill: goalkeepers (n = 17), field players (n = 20) and control group (n = 20). An eye tracker was worn whilst watching 40 videos of a striker kicking to four corners of a goal in random order. All 40 videos were temporally occluded at foot-to-ball contact, and the non-kicking leg of 20 videos was spatially manipulated. Results showed that goalkeepers had significantly better predictions than the two groups with no differences between the two testing conditions. According to effect size, the percentage of fixation location and viewing time of the kicking leg and ball were greater for the goalkeepers and field players group than the control group irrespective of testing conditions. The fixations on the kicking leg and ball in conjunction with comparable predictions between spatially manipulated and control conditions suggest that goalkeepers may not rely on the non-kicking leg. Furthermore, goalkeepers appear to use a global perceptual approach by anchoring on a distal fixation point/s of the penalty taker whilst using peripheral vision to obtain additional information.  相似文献   
979.
A motor skills assessment could be helpful in talent development by estimating essential perceptuo-motor skills of young players, which are considered requisite to develop excellent technical and tactical qualities. The Netherlands Table Tennis Association uses a motor skills assessment in their talent development programme consisting of eight items measuring perceptuo-motor skills specific to table tennis under varying conditions. This study aimed to investigate this assessment regarding its reproducibility, internal consistency, underlying dimensions and concurrent validity in 113 young table tennis players (6–10 years). Intraclass correlation coefficients of six test items met the criteria of 0.7 with coefficients of variation between 3% and 8%. Cronbach’s alpha valued 0.853 for internal consistency. The principal components analysis distinguished two conceptually meaningful factors: “ball control” and “gross motor function.” Concurrent validity analyses demonstrated moderate associations between the motor skills assessment’s results and national ranking; boys r = ?0.53 (< 0.001) and girls r = ?0.45 (= 0.015). In conclusion, this evaluation demonstrated six test items with acceptable reproducibility, good internal consistency and good prospects for validity. Two test items need revision to upgrade reproducibility. Since the motor skills assessment seems to be a reproducible, objective part of a talent development programme, more longitudinal studies are required to investigate its predictive validity.  相似文献   
980.
Citrulline has been proposed as an ergogenic aid, leading to an interest in watermelon given its high citrulline concentration. The aim of this study was to determine the effects of a single, pre-exercise dose of l-citrulline, watermelon juice, or a placebo on the total maximum number of repetitions completed over 5 sets, time to exhaustion, maximal oxygen consumption (VO2max), anaerobic threshold, and flow-mediated vasodilation. A randomised double-blind within-participants study design was used to examine these effects among 22 participants (n = 11 males). Supplementation included either a 7.5% sucrose drink containing 6 g of l-citrulline, 710 mL of watermelon juice (~1.0 g citrulline), or a 7.5% sucrose placebo drink. Supplementation was administered 1 or 2 h before exercise testing to investigate a timing effect. There was no significant effect between the three supplements for the total number of repetitions, time to exhaustion, VO2max, anaerobic threshold, or flow-mediated vasodilation. There was also no interaction observed relative to gender or supplement timing (P > 0.05). A single dose of l-citrulline or watermelon juice as a pre-exercise supplement appears to be ineffective in improving exercise performance; however, greater doses of l-citrulline have been shown to be safe and are currently left unexamined.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号