全文获取类型
收费全文 | 4093387篇 |
免费 | 295478篇 |
国内免费 | 10441篇 |
专业分类
耳鼻咽喉 | 58104篇 |
儿科学 | 132616篇 |
妇产科学 | 114214篇 |
基础医学 | 574185篇 |
口腔科学 | 118589篇 |
临床医学 | 373282篇 |
内科学 | 791000篇 |
皮肤病学 | 94284篇 |
神经病学 | 335025篇 |
特种医学 | 158478篇 |
外国民族医学 | 1267篇 |
外科学 | 614443篇 |
综合类 | 92299篇 |
现状与发展 | 11篇 |
一般理论 | 1614篇 |
预防医学 | 318790篇 |
眼科学 | 94631篇 |
药学 | 302451篇 |
15篇 | |
中国医学 | 8219篇 |
肿瘤学 | 215789篇 |
出版年
2018年 | 42849篇 |
2017年 | 33058篇 |
2016年 | 37870篇 |
2015年 | 42564篇 |
2014年 | 59267篇 |
2013年 | 90311篇 |
2012年 | 118894篇 |
2011年 | 126634篇 |
2010年 | 76239篇 |
2009年 | 72684篇 |
2008年 | 118660篇 |
2007年 | 127055篇 |
2006年 | 128564篇 |
2005年 | 124067篇 |
2004年 | 119815篇 |
2003年 | 115861篇 |
2002年 | 111872篇 |
2001年 | 188299篇 |
2000年 | 193711篇 |
1999年 | 163620篇 |
1998年 | 48006篇 |
1997年 | 42630篇 |
1996年 | 42371篇 |
1995年 | 41005篇 |
1994年 | 37966篇 |
1993年 | 35619篇 |
1992年 | 129658篇 |
1991年 | 125850篇 |
1990年 | 122319篇 |
1989年 | 118442篇 |
1988年 | 109412篇 |
1987年 | 107565篇 |
1986年 | 101820篇 |
1985年 | 97519篇 |
1984年 | 73495篇 |
1983年 | 62483篇 |
1982年 | 37495篇 |
1981年 | 33704篇 |
1979年 | 67509篇 |
1978年 | 48209篇 |
1977年 | 41296篇 |
1976年 | 38099篇 |
1975年 | 41494篇 |
1974年 | 49364篇 |
1973年 | 47429篇 |
1972年 | 44673篇 |
1971年 | 41799篇 |
1970年 | 38834篇 |
1969年 | 37166篇 |
1968年 | 34441篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
91.
92.
93.
94.
95.
F. Spöler M. Först Y. Marquardt D. Hoeller H. Kurz H. Merk F. Abuzahra 《Skin research and technology》2006,12(4):261-267
BACKGROUND: Three dimensional skin equivalents are widely used in dermatopharmacological and toxicological studies and as autologous transplants in wound healing. In pharmacology, there is tremendous need for monitoring the response of engineered skin equivalents to external treatment. Transplantation of skin equivalents for wound healing requires careful verification of their quality prior to transplantation. Optical coherence tomography (OCT) is a non-contact, non-destructive imaging technique for living tissues offering the potential to fulfill these needs. This work presents an analysis of OCT for high-resolution monitoring of skin equivalents at different stages during the culture process. METHODS: We developed a high-resolution OCT imaging setup based on a commercially available OCT system. A broadband femtosecond laser light source replaces the original superluminescence diode. Tomograms of living skin equivalents were recorded with an axial resolution of 3 mum and correlated with histology and immunofluorescence images. Comparison with standard low-resolution OCT is presented to emphasize the advantages of high-resolution OCT for this application. RESULTS: OCT is particularly able to distinguish between different layers of skin equivalents including stratum corneum, epidermal and dermal layer as well as the basement membrane zone. The high-resolution OCT scans correlate closely with two key benchmarks, histology and immunofluorescence imaging. CONCLUSIONS: This study clearly demonstrates the benefits of high-resolution OCT for identifying living tissue structure and morphology. Compared with the current gold standard histology, OCT offers non-destructive tissue imaging, enabling high-resolution evaluation of living tissue morphology and structure as it evolves. 相似文献
96.
D Van Neste† RM Trüeb‡ 《Journal of the European Academy of Dermatology and Venereology》2006,20(5):578-583
BACKGROUND: Computer-assisted image analysis has been proposed for human hair growth studies. METHODS: The performances of Trichoscan, a commercially available automated system combining epiluminiscence microscopy with digital image analysis, developed for office-based hair growth measurements, have been evaluated comparatively on the same skin sites using standardized photographic equipment and calibrated processing for contrast-enhanced phototrichogram (CE-PTG) analysis. This reference method has been validated with scalp biopsies and histological examination of serial sectioning. RESULTS: Besides edge effects, hair fibres escaped the Trichoscan analysis for various reasons including, but not limited to, thickness, pigmentation, closeness and crossing. CONCLUSION: Most of these problems have been identified in the late 1980s and remain largely unsolved by the processing software that was evaluated in 2004. Therefore claims promoting the Trichoscan method for accurate hair measurements in clinical trials on scalp and body hair are not supported by the present investigation. The speed at which the analysis is performed is outweighed by the errors in signal detection. Therefore we suggest that improvements must be clearly documented before Trichoscan is established for quantified diagnostic purposes and detailed hair cycle monitoring during hair trials. 相似文献
97.
C F A Peralta P Cavoretto B Csapo O Falcon K H Nicolaides 《Ultrasound in obstetrics & gynecology》2006,27(2):128-133
OBJECTIVE: To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. METHODS: Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. RESULTS: The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. CONCLUSIONS: In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined. 相似文献
98.
99.
K M Sarraf M Abdalla O Al-Omari M G Sarraf 《Ultrasound in obstetrics & gynecology》2006,27(2):220-221
We report the case of a 38-year-old woman who presented with chronic lower abdominal pain. Her past medical history included a splenectomy due to abdominal trauma. Ultrasound examination revealed four pelvic tumors which, upon laparotomy, were found to be the result of splenosis. Approximately 100 cases of splenosis have been reported but only a minority of them have been published in the gynecological literature. Our case indicates that those involved in pelvic scanning (even of asymptomatic women) and/or treating those complaining of lower abdominal pain or presenting with pelvic tumors should be aware of splenosis as a possible diagnosis. 相似文献
100.
B Sedgmen C McMahon D Cairns R J Benzie R L Woodfield 《Ultrasound in obstetrics & gynecology》2006,27(3):245-251
OBJECTIVE: To explore the impact of timing and type of ultrasound, particularly three-dimensional (3D), exposure on maternal-fetal attachment and maternal health behavior during pregnancy. METHODS: Subjects were 68 women aged 18 years or older expecting their first child who presented for a routine ultrasound scan at around either 12 or 18 weeks' gestation in Nepean Hospital, Western Sydney. Women completed questionnaires assessing maternal-fetal attachment and health behavior, and were then allocated arbitrarily to either two-dimensional (2D) or 3D ultrasound examination. Repeat questionnaires were completed 1 week later. RESULTS: Maternal-fetal attachment increased after both 2D and 3D ultrasound exposure, and the effect was moderated by the timing of exposure, with women receiving their first ultrasound examination at around 12 weeks showing the greatest change. Alcohol consumption was the only behavior to show significant change following ultrasound exposure, with a reduction in the reported average number of drinks per week. There was no significant difference in the pattern of change for 2D compared with 3D ultrasound exposure, and no effect of ultrasound exposure on maternal perception of the fetus. CONCLUSIONS: Ultrasound has a positive impact on maternal-fetal attachment, particularly in the first trimester. 3D ultrasound did not offer enhanced benefits. Associations between ultrasound exposure and alcohol consumption warrant further investigation. Larger samples are needed to clarify the moderating effects of gestational age and type of ultrasound exposure. 相似文献