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   1082411篇
  免费   116053篇
  国内免费   682篇
  2018年   9829篇
  2016年   13248篇
  2015年   18132篇
  2014年   21255篇
  2013年   30822篇
  2012年   33973篇
  2011年   34660篇
  2010年   23569篇
  2009年   21598篇
  2008年   30789篇
  2007年   31738篇
  2006年   29980篇
  2005年   28829篇
  2004年   28759篇
  2003年   27700篇
  2002年   26866篇
  2001年   47587篇
  2000年   47954篇
  1999年   38111篇
  1998年   13416篇
  1997年   13945篇
  1996年   13018篇
  1995年   12748篇
  1994年   12439篇
  1993年   12280篇
  1992年   32023篇
  1991年   31194篇
  1990年   30579篇
  1989年   29959篇
  1988年   27899篇
  1987年   26278篇
  1986年   24511篇
  1985年   24706篇
  1984年   20493篇
  1983年   17438篇
  1982年   13410篇
  1981年   11984篇
  1980年   11224篇
  1979年   19145篇
  1978年   14949篇
  1977年   13778篇
  1976年   12699篇
  1975年   14065篇
  1974年   15043篇
  1973年   14911篇
  1972年   13582篇
  1971年   12407篇
  1970年   10707篇
  1969年   10482篇
  1968年   9567篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
21.
22.
23.
24.
25.
26.
27.
There is considerable need for accurate suicide risk assessment for clinical, screening, and research purposes. This study applied the tripartite affect-behavior-cognition theory, the suicidal barometer model, classical test theory, and item response theory (IRT), to develop a brief self-report measure of suicide risk that is theoretically-grounded, reliable and valid. An initial survey (n = 359) employed an iterative process to an item pool, resulting in the six-item Suicidal Affect-Behavior-Cognition Scale (SABCS). Three additional studies tested the SABCS and a highly endorsed comparison measure. Studies included two online surveys (Ns = 1007, and 713), and one prospective clinical survey (n = 72; Time 2, n = 54). Factor analyses demonstrated SABCS construct validity through unidimensionality. Internal reliability was high (α = .86-.93, split-half = .90-.94)). The scale was predictive of future suicidal behaviors and suicidality (r = .68, .73, respectively), showed convergent validity, and the SABCS-4 demonstrated clinically relevant sensitivity to change. IRT analyses revealed the SABCS captured more information than the comparison measure, and better defined participants at low, moderate, and high risk. The SABCS is the first suicide risk measure to demonstrate no differential item functioning by sex, age, or ethnicity. In all comparisons, the SABCS showed incremental improvements over a highly endorsed scale through stronger predictive ability, reliability, and other properties. The SABCS is in the public domain, with this publication, and is suitable for clinical evaluations, public screening, and research.  相似文献   
28.
29.
Botrytis allii andCollectotrichum dematium are onion pathogens which can infect in the field and cause decay in storage. Some phenolics can hinder development of these fungi, but the effect of cytokinins is not clear. Cytokinins (kinetin or 6-benzyladenine) or phenolics (caffeic or chlorogenic acids) were added to agar at concentrations of 0 to 10–3 M. Cultures were continuously irradiated with fluorescent light or maintained in the dark for 6 days. On unamended media, final mycelial elongation was 45 or 17.8 mm and sporulation was 28 or 10.6 × 104 spores/ml forBotrytis andColletotrichum, respectively. ForBotrytis, mycelial elongation was slightly (5%) but significantly increased and sporulation increased by 21% by incubation on phenolics as compared to cytokinins. Mycelial extension ofColletotrichum was not affected by amendment. Sporulation ofColletotrichum on kinetin was 16 to 28% greater than on the other amendments. As amendments concentration increased elongation of mycelia of both fungi decreased. Sporulation ofBotrytis increased by 60% as amendment concentration increased from 0 to 10–5 M and then decreased 25% at 10–3 M. As amendment concentration increased from 0 to 10–3 M, sporulation ofColletotrichum increased by 45%. Incubation in light increased mycelial extension 3 to 17% forBotrytis andColletotrichum respectively, and sporulation was increased approximately 78% for both fungi. These compounds do not appear to inhibit development of theseBotrytis orColletotrichum species in culture.  相似文献   
30.
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