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   9274篇
  免费   446篇
  2023年   80篇
  2022年   68篇
  2021年   119篇
  2020年   188篇
  2019年   221篇
  2018年   294篇
  2017年   290篇
  2016年   365篇
  2015年   255篇
  2014年   253篇
  2013年   1060篇
  2012年   454篇
  2011年   540篇
  2010年   317篇
  2009年   350篇
  2008年   423篇
  2007年   427篇
  2006年   353篇
  2005年   311篇
  2004年   348篇
  2003年   353篇
  2002年   294篇
  2001年   183篇
  2000年   179篇
  1999年   158篇
  1998年   146篇
  1997年   115篇
  1996年   100篇
  1995年   99篇
  1994年   106篇
  1993年   69篇
  1992年   108篇
  1991年   66篇
  1990年   96篇
  1989年   74篇
  1988年   60篇
  1987年   58篇
  1986年   65篇
  1985年   66篇
  1984年   55篇
  1983年   69篇
  1982年   57篇
  1981年   42篇
  1980年   37篇
  1979年   54篇
  1978年   55篇
  1977年   33篇
  1976年   30篇
  1974年   19篇
  1972年   23篇
排序方式: 共有9720条查询结果,搜索用时 15 毫秒
941.
The length of the stagnant stage during the new ferrite growth starting from a mixture of austenite and ferrite has been investigated for a Fe-0.17Mn-0.023C (wt%) alloy. It was found that the stagnant stage depends on the thermal path followed to create the mixture, and deduce that the tie-lines for austenite to ferrite transformation are quite different from those for ferrite to austenite transformation. The length of the stagnant stage is determined by the very local partitioning effect at the interface, and it can be used as a tool to monitor the Mn partitioning.  相似文献   
942.
Since the 1930s it has been widely acknowledged that agricultural crop diversity is being lost at an alarming rate. The international response to this genetic erosion has principally taken the form of ex situ genebanks. In these facilities and in the international regulatory frameworks that now surround them, it is genetic diversity that is the focus of conservation efforts. This focus, however, passes over the many other important diversities—both biological and social (or ‘biosocial’)—that exist in, and depend on, agricultural environments. These diversities cannot be conserved in genebanks. In addition to failing to actually conserve agricultural diversity (in any full sense of the term), ex situ banking projects also produce important potential inequalities—in terms of which material is banked and who has access to it. If, however, we refuse to accept an exclusive focus on the genetic components of plants, and instead insist on a brand of conservation that includes whole biosocial, more-than-human communities, then the role of banked resources must be radically rethought. Genebanks might instead take the place of central nodes in networks of diversity sharing, helping to keep plant varieties growing and circulating. This focus, in turn, requires that we also pay more critical attention to the various economic, legal and other mechanisms that prevent or stifle the flow and development of plant genetic resources in/to agricultural communities—especially those of peasant and indigenous farmers that play such a crucial role in conserving the world's (agro)biodiversity.  相似文献   
943.
944.
Although Isaiah Berlin's critique of positive liberty has achieved canonical status, its place within his wider political philosophy remains obscure. However, the re-publication of one of his most important philosophical essays, From Hope and Fear Set Free, as part of a new edition of Four Essays on Liberty, simply entitled Liberty, has opened the door to a re-evaluation of Berlin's political project.

At the heart of Berlin's argument, which gains its fullest expression in From Hope and Fear Set Free, stands his contention that positive liberty, in its incarnation as self-realisation, conflates liberty with knowledge, which leads to the distortion of our phenomenologically inescapable structure of experience. This transgression against the conceptual framework in terms of which we think, Berlin argues, played its desolate part in linking the ‘totalitarian temptation’ latent in liberty as self-realisation with the totalitarian politics of the mid-twentieth century.  相似文献   
945.
It has been argued with some justice by commentators from Walter Kaufmann to Thomas Hurka that Nietzsche's positive ethical position is best understood as a variety of virtue theory – in particular, as a brand of perfectionism. For Nietzsche, value flows from character. Less attention has been paid, however, to the details of the virtues he identifies for himself and his type. This neglect, along with Nietzsche's frequent irony and non-standard usage, has obscured the fact that almost all the virtues he praises are intellectual rather than moral. The vices he most despises include dogmatism, intellectual partisanship, faith, boredom, the desire for certainty and pity. The virtues he most appreciates include curiosity, honesty, scepticism, creativity, the historical sense, intellectual courage and intellectual fastidiousness. These tables of values place Nietzsche squarely among so-called responsibilist virtue epistemologists, such as Lorraine Code and Linda Zagzebski, who emphasize that knowledge is infused with desire and affect. I argue that curiosity construed as the specification of the will to power in the domain of epistemology is the cardinal Nietzschean virtue, and that the others – especially intellectual courage and honesty – are presupposed by curiosity. Thus, Nietzsche turns out to accept his own peculiar brand of the thesis of the unity of virtue.  相似文献   
946.
Despite the increasingly recognized importance of spatial ability in STEM (science, technology, engineering, and mathematics) fields, research to date has largely ignored distinctions in the criterion‐related validity and subgroup differences associated with theoretically distinct spatial abilities. This study aims to enhance practical understanding by spotlighting a prominent military context as an example wherein specific spatial abilities may be both differentially relevant and differentially apt to result in adverse impact. Analyses compared the relative importance of (i) spatial orientation, (ii) visualization, (iii) closure flexibility, and (iv) perceptual speed for predicting U.S. Air Force pilot performance (N = 1440), and compared subgroup differences in a large applicant sample (N = 10,643). Given that specific spatial abilities vary substantially in the extent to which gender differences exist, this study highlights the practical implications associated with the choice of particular spatial ability measures in personnel selection.  相似文献   
947.
The capability of adult and child witnesses to accurately recollect events from the past and provide reliable testimony has been hotly debated for more than 100 years. Prominent legal cases of the 1980s and 1990s sparked lengthy debates and important research questions surrounding the fallibility and general reliability of memory. But what lessons have we learned, some 35 years later, about the role of memory in the judicial system? In this review, we focus on what we now know about the consequences of the fallibility of memory for legal proceedings. We present a brief historical overview of false memories that focuses on three critical forensic areas that changed memory research: children as eyewitnesses, historic sexual abuse and eyewitness (mis)identification. We revisit some of the prominent trials of the 1980s and 1990s to not only consider the role false memories have played in judicial decisions, but also to see how this has helped us understand memory today. Finally, we consider the way in which the research on memory (true and false) has been successfully integrated into some courtroom procedures.  相似文献   
948.
949.
Recent theoretical models highlighting the role of imagery in trauma and aversion learning focus on the role of images in memory (e.g., Brewin, Dalgleish, & Joseph, 1996) and images as substitute stimuli in aversive conditioning (Dadds, Bovbjerg, Redd, & Cutmore, 1997). An unanswered question is whether individual differences in imagery are associated with different rates of traumatisation and aversion states (fear and avoidance of various stimuli). We examine one aspect of this: does high imagery ability correlate with the frequency with which people report aversions? Three samples of university students were tested on the Betts Questionnaire Upon Mental Imagery, the Tellegen Absorption Scale, and a new measure we designed to sample of range of aversions. As hypothesised, vividness of imagery showed positive correlations with number of aversions reported. This relationship held after controlling for general neuroticism and proneness to disgust. Results for absorption showed no relationship. The results are unable to disentangle causal paths but suggest a focus on individual differences in imagery vividness may be fruitful for understanding individual differences in aversion learning.  相似文献   
950.
Two experiments investigated recall following two study conditions, (1) repeated test: a study trial followed by multiple recall trials, and (2) repeated study: multiple study trials with no tests. At a retention interval of 5 minutes, repeated study produced a higher level of recall than repeated test. When the retention interval was extended, forgetting was much more rapid in the study condition, with the repeated test manipulation leading to higher recall at an interval of 7 days. We conclude that study and test trials have different effects upon memory, with study trials promoting memory acquisition, and test trials enhancing the retrieval process itself, which protects against subsequent forgetting.  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