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   5606篇
  免费   634篇
  国内免费   202篇
医药卫生   6442篇
  2024年   27篇
  2023年   111篇
  2022年   300篇
  2021年   374篇
  2020年   391篇
  2019年   193篇
  2018年   163篇
  2017年   251篇
  2016年   249篇
  2015年   198篇
  2014年   488篇
  2013年   415篇
  2012年   389篇
  2011年   437篇
  2010年   318篇
  2009年   310篇
  2008年   256篇
  2007年   311篇
  2006年   242篇
  2005年   181篇
  2004年   132篇
  2003年   119篇
  2002年   72篇
  2001年   76篇
  2000年   51篇
  1999年   49篇
  1998年   32篇
  1997年   31篇
  1996年   35篇
  1995年   25篇
  1994年   23篇
  1993年   23篇
  1992年   21篇
  1991年   18篇
  1990年   15篇
  1989年   10篇
  1988年   6篇
  1987年   12篇
  1986年   7篇
  1985年   15篇
  1984年   5篇
  1983年   5篇
  1982年   8篇
  1981年   8篇
  1980年   9篇
  1979年   11篇
  1978年   9篇
  1977年   4篇
  1975年   2篇
  1974年   3篇
排序方式: 共有6442条查询结果,搜索用时 31 毫秒
41.
目的 探讨提高神经内科临床医学实习生临床思维能力的方法。方法 选择2017年至2018年临床医学实习生为研究对象,2018年为试验组(98人),2017年为对照组(95人)。试验组实施临床思维能力培养,对照组采用传统常规的方法培养。实习结束前,采用自制的《临床医学实习生临床思维能力调查问卷》进行调查,评价教学效果。使用SPSS 14.0进行t检验和卡方检验。结果 试验组与对照组均存在临床思维的片面性、表像性、定势性、被动性、懒惰性、简化性、混乱性等问题,试验组存在的临床思维方面问题较对照组明显下降(P<0.001),其中试验组的临床思维的片面性、表像性、定势性、被动性、懒惰性方面与对照组比较差异有统计学意义(P<0.05)。除语言沟通与表达能力外,试验组的其他临床思维能力自评得分与对照组比较差异都有统计学意义(P<0.05)。试验组的出科考核成绩与对照组比较差异也有统计学意义(P<0.05)。结论 临床医学生在神经内科实习阶段实施临床思维训练,有利于培养学生的临床思维能力,提高人才培养质量。  相似文献   
42.
谢逍  魏继鸿  刘双  李淳  廖波  王扬洁 《西部医学》2023,35(6):875-880
探讨低频脉冲电刺激联合摄食-吞咽训练在急性缺血性脑卒中(AIS)后吞咽障碍的应用及对呼吸能力、吞咽功能、营养指标的影响。方法 选取本院2019年6月—2021年8月107例AIS后吞咽功能障碍患者,随机分为观察组(n=54)和对照组(n=53),对照组给予摄食-吞咽训练,观察组在对照组的基础上使用低频脉冲电刺激治疗,两组均持续治疗1个月,比较两组治疗前后吞咽功能、舌骨喉复合体动度、喉镜吞咽功能(FEES)评估结果、呼吸功能、营养指标以及并发症发生情况。结果 观察组治疗后洼田饮水试验评定、标准吞咽功能评价量表(SSA)评分、吞咽功能初筛量表(EAT-10)评分低于对照组(P<0.05);观察组治疗后舌骨喉复合体动度包括舌骨向前、上移以及喉向前、喉上移最大幅度均大于对照组(P<0.05);观察组治疗后FEES评价中声带麻痹、食物渗漏、食物潴留、误吸比例低于对照组(P<0.05);观察组治疗后肺功能指标最长呼气时间、第一秒用力呼气容积(FEV1)、用力肺活量(FVC)以及最大吸气压(PImax)均大于对照组(P<0.05);观察组治疗后营养指标BMI指数、血清总蛋白(TP)、白蛋白(ALB)、转铁蛋白(TRF)、前白蛋白(PALB)水平均高于对照组(P<0.05);观察组吸入性肺炎发生率低于对照组,营养不良发生率为低于对照组(均P<0.05)。结论 低频脉冲电刺激联合摄食-吞咽训练治疗AIS后吞咽障碍,可有效促进吞咽功能恢复,改善舌骨喉复合体动度,增强呼吸功能,提高营养状态,降低并发症发生风险  相似文献   
43.
Chronic arthritis may have great impact on the patient but also on his or her family, relatives and friends. The assessment of the consequences of chronic arthritis and the effect of therapy not only in terms of physical, but also psychological and social dimensions deserves more attention. Functional ability and health status can be measured using a questionnaire or ‘instrument’, high-lighting important aspects not quantified with more traditional measurements. In this paper, arguments to apply such instruments more frequently are given. Health status instruments can be used not only to assess beneficial but also deleterious (side-)effects of therapeutic interventions. The properties are summarized of the most frequently used instruments assessing functional ability and health status. Many of these instruments have been evaluated sufficiently for validity and reliability; their sensitivity to detect change seems to be satisfactory. Therefore it is advisable to choose an internationally accepted, frequently used instrument, reflecting the area of interest.  相似文献   
44.
To test the hypothesis that the etiology of covariation among measures of cognitive ability and academic achievement is due at least in part to shared genetic influences, data from 198 adoptive and 220 nonadoptive families participating in the Colorado Adoption Project were subjected to multivariate behavioral genetic analyses. Data on measures of cognitive ability (verbal comprehension and perceptual organization) and academic achievement (reading recognition and mathematics achievement) from related and unrelated sibling pairs tested at age 7, as well as from adoptive and nonadoptive parents, were analyzed. Phenotypic analyses confirmed previous findings of moderate correlations among measures of cognitive ability and achievement, averaging about .35. Although 54% of the covariation between reading and mathematics achievement was due to influences shared with verbal ability, a significant proportion of this covariation was independent of the cognitive ability measures. Heritabilities for the various measures were moderate, ranging from .21 to .37. Moreover, genetic influences accounted for 33–64% of their phenotypic covariation; for example, 33–60% of the observed correlations between verbal comprehension and the achievement measures, 64% of those between perceptual organization and the achievement measures, and 63% of that between reading recognition and mathematics achievement were due to shared genetic influences. Similar to the results of the phenotypic analysis, nearly half of the genetic covariance between reading and mathematics achievement was independent of cognitive ability. Their remaining covariance was due primarily to nonshared environmental influences.  相似文献   
45.
A relationship is found between the resistance ofEscherichia coli, Staphylococcus aureus, andStaphylococcus epidermidis to human serum and whole blood and their ability to inactivate the factors of natural antiinfectious resistance (lysozyme, complement, immunoglobulins, and a bactericidal fraction of leukocytic interferon). Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N o 2, pp. 174–176, February, 1996  相似文献   
46.
Mating ability differences between flies of different alcohol dehydrogenase (Adh) genotypes have been assessed in the temperature range 15 to 29°C for laboratory-adapted and field-derivedDrosophila melanogaster. Significant differences amongAdh genotypes were detected principally for the laboratory-adapted strains due to departures from random mating associated with heterozygote superiority at the relatively extreme temperature of 29°C, although mating ability differences could not be attributed directly to theAdh locus. The difference between the laboratory and the field populations can be explained by the effects of genetic back-ground manifested in the form of fitness differences, being enhanced for the laboratory-adapted flies as a consequence of the stress of laboratory culture. In contrast with larval survival and development time, laboratory and field flies do not differe appreciably in their overall abilities to obtain mates, which indicates that mating ability is a direct fitness character not greatly affected by laboratory culture. It follows that direct fitness traits are the least amenable to change under domestication.  相似文献   
47.
Three assays to determine the repopulation potential of stem cells in murine bone marrow grafts were evaluated on their reliability with regard to the ranges in graft size. In vivo, marrow repopulating ability, as calculated from the number of in vitro clonable progenitors (colony-forming units in culture, CFU-C) generated by the graft in the femur of an irradiated recipient, appeared to be independent of the input over a wide range of cell numbers grafted. A second assay, erythroid repopulating ability is a measure of the number of new reticulocytes or erythrocytes in the blood generated by the graft, and significantly underestimates stem cell activity of the graft. The third assay measures the long-term repopulating ability of bone marrow cells in vitro on pre-established stromal cell layers by determination of the number of CFU-C produced in these cultures. Calculations of short-term in vitro repopulating ability, done from measurements of the production of non-adherent CFU-C in the first week of culture, appeared to be independent of cell input. Long-term in vitro repopulating potential, measured by the CFU-C content of the adherent layer at 4 weeks, is also independent of the numbers of cell input.  相似文献   
48.
Genetic Structure of Spatial and Verbal Working Memory   总被引:6,自引:0,他引:6  
Ando J  Ono Y  Wright MJ 《Behavior genetics》2001,31(6):615-624
Working memory (WM) encompasses both short-term memory (storage) and executive functions that play an essential role in all forms of cognition. In this study, the genetic structure of storage and executive functions engaged in both a spatial and verbal WM span task is investigated using a twin sample. The sample consists of 143 monozygotic (MZ) and 93 dizygotic (DZ) Japanese twin pairs, ages 16 to 29 years. In 155 (87 MZ, 62 DZ) of these pairs, cognitive ability scores from the Kyodai Japanese IQ test are also obtained. The phenotypic relationship between WM and cognitive ability is confirmed (r = 0.26–0.44). Individual differences in WM storage and executive functions are found to be significantly influenced by genes, with heritability estimates all moderately high (43%–49%), and estimates for cognitive ability comparable to previous studies (65%). A large part of the genetic variance in storage and executive functions in both spatial and verbal modalities is due to a common genetic factor that accounts for 11% to 43% of the variance. In the reduced sample, this common genetic factor accounts for 64% and 26% of the variance in spatial and verbal cognitive ability, respectively. Additional genetic variance in WM (7%–30%) is due to modality specific factors (spatial and verbal) and a storage specific factor that may be particularly important for the verbal modality. None of the variance in cognitive ability is accounted for by the modality and storage genetic factors, suggesting these may be specific to WM.  相似文献   
49.
Pedersen  N. L.  McClearn  G. E.  Plomin  R.  Friberg  L. 《Behavior genetics》1985,15(4):407-419
Thirty-four pairs of Swedish fraternal twins separated in the first 10 years of life were administered 12 tests of cognitive abilities. The average age of the twins was 59 years. Nineteen pairs were separeted before the first year of life and 26 pairs (76%) were separated by the age of 5 years. Moderate positive twin correlations were found for all tests, reaching significance for Raven's Progressive Matrices and Word Beginnings and Endings. A twin correlation of 0.52 emerged for the first principal component (a measure of general ability). Moderate correlations were found for Spatial Ability and for Verbal Ability/Perceptual Speed factors; for the Memory factor the correlation was lower. The effect of early environment on cognitive ability was assessed by analyzing the association between a degree of separation index and twin resemblance. The importance of the separation measures taken individually was also examined. Some significant effects were found, but these were consistently in a counterintuitive direction: Twins separated earlier weremore similar than those separated later.This research was supported in part by National Institute on Aging Grant AG-01592.  相似文献   
50.
The goal of this study was to investigate the factors responsible for the low subitizing limit of cerebral palsied (CP) children. For this purpose, 44 CPs were tested on two tasks involving the rapid recognition of dot configurations. The answer was either a number (subitizing task) or the name of a pattern (pattern recognition task). The CPs were compared to controls of the same age. All children were evaluated for visual and visuospatial short-term memory. The results showed that CPs with a low subitizing limit did not do better with a canonical arrangement than the random one, were impaired to the same extent on the pattern recognition task as on the subitizing task, and had a short visuospatial short-term memory span. These results suggest that the low subitizing limit of CPs stems from a (non-number-dependent) lesser capacity to perceive a dot configuration as a gestalt. A low subitizing limit was almost always associated with a right-hemisphere lesion.  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