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   500719篇
  免费   33495篇
  国内免费   11471篇
耳鼻咽喉   5275篇
儿科学   11727篇
妇产科学   9239篇
基础医学   49125篇
口腔科学   10958篇
临床医学   47898篇
内科学   63526篇
皮肤病学   6515篇
神经病学   30132篇
特种医学   13858篇
外国民族医学   32篇
外科学   49378篇
综合类   72018篇
现状与发展   29篇
一般理论   37篇
预防医学   48262篇
眼科学   7358篇
药学   53132篇
  428篇
中国医学   41148篇
肿瘤学   25610篇
  2023年   7597篇
  2022年   14521篇
  2021年   19840篇
  2020年   17677篇
  2019年   22830篇
  2018年   20713篇
  2017年   18582篇
  2016年   16229篇
  2015年   15297篇
  2014年   25878篇
  2013年   31085篇
  2012年   25893篇
  2011年   29065篇
  2010年   21704篇
  2009年   20553篇
  2008年   21632篇
  2007年   22981篇
  2006年   20750篇
  2005年   18492篇
  2004年   15399篇
  2003年   13604篇
  2002年   10745篇
  2001年   9664篇
  2000年   8028篇
  1999年   6866篇
  1998年   5540篇
  1997年   5510篇
  1996年   4876篇
  1995年   4484篇
  1994年   4343篇
  1993年   3549篇
  1992年   3448篇
  1991年   3074篇
  1990年   2686篇
  1989年   2307篇
  1988年   2217篇
  1987年   1972篇
  1986年   1818篇
  1985年   4813篇
  1984年   5582篇
  1983年   3945篇
  1982年   4415篇
  1981年   4047篇
  1980年   3642篇
  1979年   3275篇
  1978年   2785篇
  1977年   2116篇
  1976年   2347篇
  1975年   1780篇
  1974年   1546篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
Background/aims: The objective and quantitative assessment of the skin is important in medical and cosmeceutical research. Assessment of color is an important element for analyzing the surface of the skin, which is usually determined subjectively by a doctor or using color analysis devices. These devices, however, cannot provide correct color information because color is construed from the mean value of the observation region, and analysis of color distribution is impossible. The purpose of this paper is to develop an objective analysis method to permit skin color measurement of each pixel unit of an image and analyze the distribution of skin surface color. Methods: The Skin Color Distribution Analyzer (SCDA) is an analysis method newly developed at the Research Institute for Skin Image at Korea University. The SCDA system presented in this paper performed a novel form of quantitative and objective analysis of skin color distribution using each pixel color model parameter found in image wavelength information. In this paper, distribution analysis was conducted on normal skin and skin lesions and skin affected by artificially induced irritant contact dermatitis and pigmented nevous. The method selected a grade using a color model parameter. Twenty healthy Korean males participated in this study. A comparative study of the eight anatomical areas was performed, including the exposure and non‐exposure parts and the medial aspect and the lateral aspect of the forearm. A reliability test for the SCDA system was also conducted with a spectrometer (SPEC) using the color analysis method. Results: Each skin lesion was precisely segmented by grade and each parameter hada different statistical significance for results of analysis of distribution in pigmented nevous and the artificially induced irritant contact dermatitis. Parameters L*, b*, a*, and EI showed salient traits. Showed resemble measured result in the SCDA system and the SPEC of normal skin. The exposed site, in comparison with the non‐exposed site, showed a notable difference in the L* parameter and a significant statistical difference in the x and z parameters, except b*. The comparison of the medial and lateral aspects of the forearm showed a notable difference in the L* parameter and a significant statistical difference in the parameters except y and b*. In the reliability test result using the SCDA system and the SPEC, the SCDA system was highly reliabile in terms of the CV value in all color model parameters. Conclusions: The color distribution analysis method using the SCDA system has revealed an aspect that the existent method of medical research has not shown, and is considered to be more reliable than other methods. This method can provide better study findings because it can be applied to other fields in addition to the medical science field and the ripple effect is thought to be bigger in other science field too.  相似文献   
122.
123.
124.
Research has shown that increasing numbers of teenagers are going online to find health information, but it is unclear whether there are disparities in the prevalence of online health seeking among young Internet users associated with social and economic conditions. Existing literature on Internet uses by adults indicates that low income, less educated, and minority individuals are less likely to be online health seekers. Based on the analysis of data from the Pew Internet and American Life Project for the US, this study finds that teens of low education parents are either as likely as or even more likely than teens of high education parents to seek online health information. Multiple regression analysis shows that the higher engagement in health seeking by teens of low education parents is related to a lower prevalence of parental Internet use, suggesting that some of these teens may be seeking online health information on behalf of their low education parents. Implications of these findings are discussed in relation to the issues of the digital divide and digital empowerment.  相似文献   
125.
PURPOSE: The purpose of this study was to measure spectrophotometrically the color stability of pigmented A-2186 silicone maxillofacial elastomer with 10% by volume of titanium white dry earth opacifier before and after exposure to microwave energy over a simulated 1.5-year period of microwave sterilization. Materials AND METHODS: A-2186 silicone elastomer opacified with titanium white dry earth pigment, pigmented with 5 cosmetic dry earth pigment colors [no pigment (control) group (Pc), red (Pr), yellow ochre (Py), burnt sienna (Po), and a mixture of Pr + Py + Po color group (P3)], was used in this study. Each of the 5 experimental groups consisted of 5 specimens. All specimens were placed in a 250 ml glass beaker filled with 150 ml of water (replenished for each microwave exposure). An exposure of 6 minutes was used 18 times (simulating 1.5 years of microwave sterilization with one 6 minute exposure monthly). Reflectance values were measured by spectrophotometer. Three- and two-way analyses of variance with repeated measures were performed for the color difference (DeltaE*) with the factors of group/color/months, and group/months, respectively. Means were compared by Tukey Honest Significant Difference (HSD) multiple range test calculated at the 0.05 level of significance using SPSS. RESULTS: The trained human eye can detect color changes (DeltaE*) greater than 1.0. Most DeltaE* values of the red pigment group at all intervals and the mixed pigment group at 15- and 18- month intervals increased significantly greater than 1.0 (p < 0.001) compared with the control group. Yellow and burnt sienna groups remained the most color stable over time with DeltaE* values below 0.35. CONCLUSIONS: Lack of color stability of red dry earth pigmented A-2186 silicone maxillofacial elastomers was clinically significant after 12-month exposure to microwave energy as compared with yellow, burnt sienna, and opacified A-2186 dry earth pigments.  相似文献   
126.
青蒿琥酯皮肤擦剂在小鼠和兔体内的药代动力学研究   总被引:1,自引:0,他引:1  
赵凯存  宣文漪  赵一  宋振玉 《药学学报》1989,24(11):813-816
将青蒿琥酯溶于苯二甲酸二甲酯,加适量氨酮制成皮肤擦剂。给兔脱毛后,皮肤涂抹此擦剂25mg/kg后,血药浓度达峰时间平均为2 h,峰浓度平均为1.80μg/ml。药物在兔体内平均驻留时间为3.54 h,清除半衰期约为2.46 h。给小鼠脱毛皮肤涂抹擦剂6.7,31.3和71.4 mg/kg,血药浓度在给药后0.5~4 h达高峰,峰浓度分别为0.82,2.05和7.11μg/ml,体内药物平均驻留时间为3.39,2.79及3.54 h,清除半衰期为2.35,1.93及2.45 h。可见,给兔及小鼠皮肤擦剂后,青蒿琥酯吸收良好,血药浓度维持时间较长。  相似文献   
127.
While much time has been spent deliberating about the definition of play, little emphasis has been placed on what children themselves perceive as play. The aim of the present study was to examine social context as a cue for children's perceptions of play and learning. Ninety-two children aged between four and six years (mean four years nine months) participated in the study and completed the Activity Apperception Story Procedure. Children were asked to sort photographic stimuli into those they believed depicted play/not play and learning/not learning. Each of the stimuli were identified by independent raters as containing one of the following social cues; teacher absence (solitary activity, parallel activity or cooperative activity) or teacher presence (teacher involved activity or teacher directed activity). Findings revealed that children associated teacher absence with play. More specifically, children made links between play and the presence of peers (parallel and cooperative activity). Findings are discussed in relation to play in the early years curriculum, differences in children's early educational experiences and the importance of understanding children's perceptions of play.  相似文献   
128.
Central Sensitization Theory of Migraine: Clinical Implications   总被引:4,自引:2,他引:2  
David Dodick  MD  ; Stephen Silberstein  MD 《Headache》2006,46(S4):S182-S191
The clinical science of migraine headache continues to evolve. Theories of the pathophysiology of migraine have progressed from the early vascular basis of migraine to more complex current theories that emphasize the centrality of neuronal dysfunction. The most recently articulated theory of migraine is the central sensitization hypothesis, which proposes that altered processing of sensory input in the brainstem, principally the trigeminal nucleus caudalis, could account for many of the temporal and symptomatic features of migraine, as well as its poor response to triptan therapy when such treatment is initiated hours after the onset of pain. Both preclinical and clinical data support the central sensitization theory. A critical clinical implication of this theory is that drugs that are capable of either aborting or arresting the process of central sensitization, most prominently dihydroergotamine, may have a unique role in the treatment of migraine. An additional, and highly practical, implication is based upon the finding that cutaneous allodynia—pain arising from innocuous stimulation of the skin, as in hair brushing or the application of cosmetics—is an easily identifiable marker of central sensitization. Thus, the presence or absence of cutaneous allodynia can be integrated into the routine clinical assessment of migraine and utilized as a determinant of treatment. Future basic and clinical research on central sensitization is likely to be of ongoing importance to the field.  相似文献   
129.
130.
Quality of life after total mesorectal excision for rectal cancer   总被引:3,自引:0,他引:3  
BACKGROUND: After total mesorectal excision for rectal cancer, many surgeons try to avoid an abdominoperineal resection (APR) by performing a transanally double stapled low colo-rectal anastomosis (LRA), frequently without a pouch. This policy is mainly based on the assumption that the quality of life after such LRA is higher than after APR. It has been suggested that a better functional outcome and therefore a higher quality of life might be achieved by a colo-anal J-pouch anastomosis (CPA). The aim of this study was to assess quality of life among disease-free survivors after APR, LRA and CPA. METHODS: The charts of 301 consecutive patients who had undergone surgery for cancer in the middle or lower third of the rectum were analysed. Two hundred four patients were eligible for inclusion. The quality of life among these patients was assessed using one generic (EQ-5D) and two disease-specific questionnaires (EORTC QLQ-C30 and EORTC QLQ-CR38). RESULTS: The response rate was 82%. The median follow-up was 31 months. Overall, quality of life was good but CPA patients had better quality of life scores than APR and LRA patients. This difference was not only due to the better functional outcome but also to the lower incidence of disturbed micturition and sexual problems in the CPA group. CONCLUSION: The quality of life after colo-anal J-pouch anastomosis is better than after abdominoperineal resection (APR) and low colo-rectal anastomosis (LRA). The quality of life after APR is similar to that after LRA.  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