首页 | 官方网站   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   962篇
  免费   55篇
工业技术   1017篇
  2023年   14篇
  2022年   13篇
  2021年   75篇
  2020年   26篇
  2019年   28篇
  2018年   30篇
  2017年   37篇
  2016年   35篇
  2015年   18篇
  2014年   30篇
  2013年   58篇
  2012年   55篇
  2011年   54篇
  2010年   53篇
  2009年   50篇
  2008年   60篇
  2007年   35篇
  2006年   23篇
  2005年   23篇
  2004年   22篇
  2003年   24篇
  2002年   26篇
  2001年   12篇
  2000年   7篇
  1999年   12篇
  1998年   12篇
  1997年   8篇
  1996年   16篇
  1995年   13篇
  1994年   12篇
  1993年   8篇
  1992年   13篇
  1991年   5篇
  1990年   10篇
  1989年   8篇
  1988年   7篇
  1987年   9篇
  1986年   7篇
  1985年   8篇
  1984年   8篇
  1983年   7篇
  1982年   4篇
  1981年   5篇
  1979年   3篇
  1978年   6篇
  1977年   3篇
  1976年   3篇
  1974年   3篇
  1970年   3篇
  1964年   2篇
排序方式: 共有1017条查询结果,搜索用时 15 毫秒
51.
What unique assessment issues do evaluators face when conducting mental retardation evaluations in capital cases? This article describes 4 assessment issues and reports how 20 evaluators in 1 state have approached them: (a) What methods are appropriate for evaluating adaptive functioning in this context? (b) Should information about criminal behavior be used as evidence of adaptive functioning? (c) Should correctional officers serve as informants regarding adaptive behavior? and (d) How should the Flynn effect influence the interpretation of intelligence test scores? Implications for practice are that practitioners should expect to be asked about the relation between criminal behavior and adaptive functioning, must think carefully about the validity of tests of adaptive functioning for inmates, and must be knowledgeable about the current state of Flynn effect research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
52.
Water-leaving reflectance (ρw) data from the European Space Agency ocean colour sensor Medium Resolution Imaging Spectrometer (MERIS) was validated with in situ ρw between October 2008 and November 2011, off Sagres on the southwest coast of the Iberian Peninsula. The study area is exceptional, since Stations A, B, and C at 2, 10, and 18 km offshore are in optically deep waters at approximately 40, 100, and 160 m, respectively. These stations showed consistently similar bio-optical properties, characteristic of Case 1 waters, enabling the evaluation of adjacency effects independent of the usual co-varying inputs of coastal waters. Using the third reprocessing of MERIS with the standard MEGS 8.1 processor, four different combinations of procedures were tested to improve the calibration between MERIS products and in situ data. These combinations included no vicarious adjustment (NoVIC), vicarious adjustment (VIC), and, for mitigating the effects of land adjacency on MERIS ρw, the improved contrast between ocean and land (ICOL) processor (version 2.7.4) and VIC + ICOL. Out of approximately 130 potential matchups for each station, 38–77%, 74–86%, and 88–90% were achieved at Stations A, B, and C, respectively, depending on which of the four combinations were used. Analyses of ρw comparing these various procedures, including statistics, scatter plots, histograms, and MERIS full-resolution images, showed that the VIC procedure compared with NoVIC produced minimal changes to the calibration. For example, at the oceanic Station C, the regression slope was closer to unity at all wavelengths with NoVIC compared to VIC, whereas, with the exception of wavelengths 412 and 443 nm, the intercept, mean ratio (MR), absolute percentage difference (APD), and relative percentage difference (RPD) were better with NoVIC. The differences for MR and APD indicate that there was marginal improvement for these two bands with VIC, and an over-adjustment with RPD. ICOL also showed inconsistent results for improving the retrieval of the near-shore conditions, but under some conditions, such as ρw at wavelength 560 nm, the improvement was striking. VIC + ICOL showed results intermediate between those of VIC and ICOL implemented separately. In relation to other validation sites, the offshore Station C at Sagres had much in common with the Mediterranean deep water, BOUSSOLE buoy, although the matchup statistics between MERIS ρw and in situ ρw were much better for Sagres than for BOUSSOLE. Strikingly, the matchup statistics for ρw at Sagres were very similar to those for the Acqua Alta Oceanographic Tower (AAOT), where the AAOT showed more scatter at 412 nm, probably because of the atmospheric correction where the aerosol optical thickness is higher at the AAOT. Conversely, Sagres showed much greater scatter at 665 nm in the red as the values were generally close to the limits of detection owing to the clearer waters at Sagres compared to the more turbid waters at the AAOT.  相似文献   
53.
The aim of this study was to determine if changes in omega‐3 polyunsaturated fatty acid status following tuna oil supplementation correlated with changes in scores of depression. A total of 95 volunteers receiving treatment for major depression were randomised to consume 8 × 1 g capsules per day of HiDHA (2 g DHA, 0.6 g EPA and 10 mg Vitamin E) or olive oil (placebo) for 16 weeks, whilst undergoing weekly counseling sessions by trained clinical psychologists using a standard empirically validated psychotherapy. Depression status was assessed using the 17 item Hamilton rating scale for depression and the Beck Depression Inventory by a psychodiagnostician who was blind to the treatment. Blood was taken at baseline and 16 weeks (n = 48) for measurement of erythrocyte fatty acids. With HiDHA supplementation, erythrocyte DHA content rose from 4.1 ± 0.2 to 7.9 ± 0.4 % (mean ± SEM, p < 0.001) of total fatty acids but did not change (4.0 ± 0.2 to 4.1 ± 0.2 %) in the olive oil group. The mean changes in scores of depression did not differ significantly between the two groups (?12.2 ± 2.1 for tuna oil and ?14.4 ± 2.3 for olive oil). However, analysis of covariance showed that in the fish oil group there was a significant correlation (r = ?0.51) between the change in erythrocyte DHA and the change in scores of depression (p < 0.05). Further study of the relationship between DHA and depression is warranted.  相似文献   
54.
Non-targeted effects (NTE) of ionizing radiation may initiate myeloid neoplasms (MN). Here, protein mediators (I) in irradiated human mesenchymal stromal cells (MSC) as the NTE source, (II) in MSC conditioned supernatant and (III) in human bone marrow CD34+ cells undergoing genotoxic NTE were investigated. Healthy sublethal irradiated MSC showed significantly increased levels of reactive oxygen species. These cells responded by increasing intracellular abundance of proteins involved in proteasomal degradation, protein translation, cytoskeleton dynamics, nucleocytoplasmic shuttling, and those with antioxidant activity. Among the increased proteins were THY1 and GNA11/14, which are signaling proteins with hitherto unknown functions in the radiation response and NTE. In the corresponding MSC conditioned medium, the three chaperones GRP78, CALR, and PDIA3 were increased. Together with GPI, these were the only four altered proteins, which were associated with the observed genotoxic NTE. Healthy CD34+ cells cultured in MSC conditioned medium suffered from more than a six-fold increase in γH2AX focal staining, indicative for DNA double-strand breaks, as well as numerical and structural chromosomal aberrations within three days. At this stage, five proteins were altered, among them IQGAP1, HMGB1, and PA2G4, which are involved in malign development. In summary, our data provide novel insights into three sequential steps of genotoxic signaling from irradiated MSC to CD34+ cells, implicating that induced NTE might initiate the development of MN.  相似文献   
55.
56.
Symmetry reduction techniques aim to combat the state-space explosion problem for model checking by restricting search to representative states from equivalence classes with respect to a group of symmetries. The standard approach to representative computation involves converting a state to its minimal image under a permutation group G, before storing the state. This is known as the constructive orbit problem (COP), and is NP{\mathit{NP}} hard. It may be possible to solve the COP efficiently if G is known to have certain structural properties: in particular if G is isomorphic to a full symmetry group, or G is a disjoint/wreath product of subgroups. We extend existing results on solving the COP efficiently for fully symmetric groups, and investigate the problem of automatically classifying an arbitrary permutation group as a disjoint/wreath product of subgroups. We also present an approximate COP strategy based on local search, and some computational group-theoretic optimisations to improve the basic approach of solving the COP by symmetry group enumeration. Experimental results using the TopSPIN symmetry reduction package, which interfaces with the computational group-theoretic system GAP, illustrate the effectiveness of our techniques.  相似文献   
57.
This study was a 5-year follow-up of obese children who participated in a family-based behavioral weight-control program targeting and reinforcing children and parents for weight loss (Epstein, Wing, Koeske, Andrasik, & Ossip, 1981). Children in the parent-plus-child group showed significantly greater weight reductions after 5 years (–22.7% overweight) than did children in a child-alone target group or in a no-target control group (4.3% and 8.2% overweight, respectively). One third of children in the parent-plus-child group were within 20% of normal weight in comparison with 5% of the children in the no-target control group. Height percentile decreased from the 72nd to the 60th percentile; these changes were negatively related to weight change. These children remained taller than the average child after weight loss, and children of short and medium-height parents were still relatively taller than their parents after 5 years. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
58.
Assessed the effect of parent weight (obese/nonobese parent) and parent control vs child self-control on the weight loss of 41 obese 8–12 yr olds over a 3-yr period. Children of nonobese parents had significantly greater decrease in relative weight after 1 yr, but not after 3 yrs, than children of obese parents. Locus of control was not related to treatment outcome over the 3 yrs. Results suggest that parent weight was related to weight loss, but not weight maintenance, in obese children. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
59.
60.
Two experiments examined long-term repetition priming in data entry. In each experiment, participants entered 4-digit numbers displayed as either words or numerals, and responded with digits (Experiment 1), or either digits or initial letters (Experiment 2). At test 1 week later, they entered old and new numbers, with the format changed for half of the old stimuli. Implicit memory was evidenced at test by faster entry of the old than the new numbers, regardless of whether the numbers were in the same or different format, suggesting that the abstract numerical meaning, not the surface form, contributes to repetition priming. Numbers presented as words in training had an advantage over numbers presented as numerals, regardless of response format, implying that type of processing also contributes to the effect and ruling out an explanation based on time spent processing numbers in word format. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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-23

京公网安备 11010802026262号