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   183064篇
  免费   1579篇
  国内免费   23篇
耳鼻咽喉   1194篇
儿科学   6872篇
妇产科学   3149篇
基础医学   17618篇
口腔科学   1846篇
临床医学   13221篇
内科学   32470篇
皮肤病学   743篇
神经病学   17214篇
特种医学   9077篇
外国民族医学   2篇
外科学   29690篇
综合类   2412篇
一般理论   19篇
预防医学   18836篇
眼科学   2874篇
药学   10074篇
中国医学   642篇
肿瘤学   16713篇
  2023年   49篇
  2022年   59篇
  2021年   166篇
  2020年   114篇
  2019年   151篇
  2018年   22095篇
  2017年   17468篇
  2016年   19632篇
  2015年   1069篇
  2014年   1037篇
  2013年   1106篇
  2012年   7413篇
  2011年   21491篇
  2010年   19084篇
  2009年   11811篇
  2008年   19925篇
  2007年   22182篇
  2006年   1018篇
  2005年   2656篇
  2004年   3840篇
  2003年   4751篇
  2002年   2915篇
  2001年   385篇
  2000年   510篇
  1999年   288篇
  1998年   309篇
  1997年   287篇
  1996年   159篇
  1995年   167篇
  1994年   144篇
  1993年   109篇
  1992年   134篇
  1991年   155篇
  1990年   205篇
  1989年   144篇
  1988年   121篇
  1987年   109篇
  1986年   80篇
  1985年   96篇
  1984年   82篇
  1983年   95篇
  1982年   70篇
  1981年   44篇
  1980年   82篇
  1979年   45篇
  1978年   48篇
  1974年   45篇
  1938年   60篇
  1932年   56篇
  1930年   48篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
This study investigates whether tissue recoil or patient intrinsic factors influence the final position of the nipple areola complex (NAC) after reduction mammoplasty. The age, pre-operative ptosis, BMI and weight of the tissue resected were recorded as patient intrinsic factors in 37 patients undergoing reduction mammoplasty. The “spring-back” value was defined as the distance from the sternal notch to a nipple landmark on the breast meridian with the patient sitting up, minus the same measurement repeated with the patient recumbent to eliminate the pull of gravity on the breast. Spring back was measured pre-operatively for the nipple and nipple mark then post-operative for the nipple. The difference in centimeters between the final post-operative distance from the sternal notch to the nipple and the level intended by the pre-operative nipple mark was termed the “judgment error.” The final position of the post-operative nipple and the judgment error was compared to the spring-back values and patient intrinsic factors. Pre-operative ptosis was statistically related to increasing patient BMI and mass of tissue resected per breast. Pre-operative spring-back values for the nipple increased with increasing ptosis, BMI and decreasing age. Spring-back values were greater in the lower pole of the breast than in the upper pole. The final position of the nipple was higher than the pre-operative mark in 65% of cases, lower in 8% and as marked in 27% of cases. The post-operative NAC was, on average, 0.6 cm higher than planned pre-operatively. The post-operative distance from the sternal notch to the nipple increased with increasing pre-operative ptosis, mass of breast tissue resected per breast and all three spring-back values. The difference between the level of the pre-operative mark and the final nipple position showed a weak correlation with post-operative spring-back values. The parameters of ptosis, BMI, weight of tissue resected per breast and pre-operative nipple spring back reflect body habitus and breast size. Spring-back values vary between the upper and lower pole of the breast. The final NAC position was higher than that intended at pre-operative marking in the majority of cases. The surgeon instinctively marks the nipple lower in patients with greater pre-operative ptosis and in whom a larger resection is anticipated. Judgment error did not relate to intrinsic factors nor to pre-operative spring-back values; hence, these parameters cannot be applied as predictive tools for more accurate pre-operative marking of the nipple position. This study suggests that the pre-operative nipple mark should be placed, with the patient sitting up, at least 23 cm from the sternal notch and 0.6 cm lower than the final position estimated using the inframammary crease as a landmark. An invited commentary on this paper is available at .  相似文献   
92.
The nasolabial fold is a significant facial landmark. Its size, shape, and symmetry are important in facial reanimation surgery, while effacement is an important goal in rejuvenation surgery. However, quantitative data for the nasolabial fold volume (NLFV) and depth is still unavailable. We present a new method of measurement using 3D color speckle stereophotogrammetry and its application in the assessment of NLFV. The VECTRA-3D system was validated to determine its minimum resolution and accuracy. Normal volunteers aged 13–84 years (n = 87) were imaged in repose. Mother–daughter pairs (n = 15, aged 13–61) were imaged in the upright and supine positions. All data were processed using custom software and analyzed by linear regression and nonparametric tests as appropriate. NLFV varied from 0.0026 to 0.2306 ml. There was significant correlation between NLFV and age (r = 0.7269, p < 0.0001). Men had significantly higher NLFV than women across all ages. There was no significant difference between the left and right NLFV. NLFV altered significantly from upright to supine in all subjects (p = 0.0012). However, the mothers increased their NLFV by 32% from supine to upright postures, which was a greater change than observed in their daughters. We have demonstrated a rapid, objective, and non-invasive assessment tool for facial reanimation and rejuvenation surgery. We have quantified the effects of age and posture on NLFV, and the efficacy and longevity of rejuvenation procedures are currently under investigation.  相似文献   
93.
94.
95.
AIM: The aim of this study was to determine the impact of asthma and air pollution on school attendance of primary school children 6 to 12 years of age in Qatar. STUDY DESIGN: This was a cross-sectional population-based study. SUBJECTS: The total 31,400 Qatari school children at the primary school (16,130 boys and 15,270 girls) 6 to 12 of age were studied to investigate school absenteeism caused by asthma and wheezing during the academic year October 2003 to July 2004. METHODS: We have used the School Health Registry for obtaining the student information and school absenteeism due to asthma and wheezing. Again we had double confirmation on the data obtained on asthmatic children by using the modified version of the International Study of Asthma and Allergies in Childhood [ISAAC] questionnaire. RESULTS: A total of 3,270 (10.4%) pupils were diagnosed as having asthma and wheezing. Overall 2,516 (8.02%) pupils were absent from the school for at least one day during the year. There was a statistically significant difference between asthmatic and wheezing students in number of days absent from the school (p < 0.0001). Most absenteeism occurred during spring for both boys (45%) and girls (47%), followed by autumn for boys (33%) and girls (36%). The measured pollutants reached a peak during the spring season and then in autumn of the studied academic year. CONCLUSION: Children with known asthma miss more days of school than those who do not have asthma. This study finding shows that air pollution has an impact on asthma, which results in significant school absenteeism.  相似文献   
96.
Conclusions  Noninvasive imaging of neurohumoral upregulation in remodeled myocardium suggests that an imaging strategy can be developed for predicting the rate of remodeling and likelihood of HF development. This should allow a more judicious use of neurohumoral antagonists especially in subjects who do not have manifest HF.74 In others specific targeted imaging may allow timely selection of individualized treatment strategies and ensure optimization of therapeutic intervention. Similar to ACE and AII receptors, multiple other targets in the hormonal cascades can identify the likelihood of adverse and favorable remodeling.74  相似文献   
97.
Two successful cases of the surgical treatment for coronary artery aneurysm (non-Kawasaki disease) were reported. The first case had a saccular aneurysm on the left circumflex coronary artery (LCx) #14. Resection of the LCx aneurysm was performed subsequent to single vessel coronary artery bypass grafting (CABG) to the distal portion of LCx#14 under the cardioplegic cardiac arrest. The second case had aneurysms on both the left anterior descending artery (LAD) #7 (fusiform) and the LCx#11 (saccular). After double vessel CABG to LAD#7 and LCx#11, ligation or resection of two aneurysms was performed successfully. Postoperative courses have been uneventful with good angiographic results achieved. Since these surgical procedures demonstrated safety, the patients are expected to achieve a good long-term prognosis.  相似文献   
98.
Late-onset chylothorax occurred 49 days after right lower lobectomy for lung cancer in a 76-year-old man. Chylothorax was successfully managed by conservative treatment with chest tube drainage and an enteral low-fat diet. Chylothorax may occur in the late period after pulmonary resection and systematic mediastinal lymph node dissection for lung cancer, for which conservative management is the treatment of choice.  相似文献   
99.
Guidelines for design of clinical trials evaluating behavioral headache treatments were developed to facilitate production of quality research evaluating behavioral therapies for management of primary headache disorders. These guidelines were produced by a Workgroup of headache researchers under auspices of the American Headache Society. The guidelines are complementary to and modeled after guidelines for pharmacological trials published by the International Headache Society, but they address methodologic considerations unique to behavioral and other nonpharmacological treatments. Explicit guidelines for evaluating behavioral headache therapies are needed as the optimal methodology for behavioral (and other nonpharmacologic) trials necessarily differs from the preferred methodology for drug trials. In addition, trials comparing and integrating drug and behavioral therapies present methodological challenges not addressed by guidelines for pharmacologic research. These guidelines address patient selection, trial design for behavioral treatments and for comparisons across multiple treatment modalities (eg, behavioral vs pharmacologic), evaluation of results, and research ethics. Although developed specifically for behavioral therapies, the guidelines may apply to the design of clinical trials evaluating many forms of nonpharmacologic therapies for headache.  相似文献   
100.
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