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   6242篇
  免费   388篇
  国内免费   19篇
耳鼻咽喉   92篇
儿科学   208篇
妇产科学   174篇
基础医学   672篇
口腔科学   145篇
临床医学   454篇
内科学   1479篇
皮肤病学   138篇
神经病学   307篇
特种医学   162篇
外科学   1168篇
综合类   200篇
一般理论   3篇
预防医学   400篇
眼科学   159篇
药学   522篇
中国医学   33篇
肿瘤学   333篇
  2023年   63篇
  2022年   131篇
  2021年   209篇
  2020年   126篇
  2019年   165篇
  2018年   205篇
  2017年   139篇
  2016年   173篇
  2015年   187篇
  2014年   199篇
  2013年   270篇
  2012年   446篇
  2011年   471篇
  2010年   230篇
  2009年   186篇
  2008年   283篇
  2007年   298篇
  2006年   286篇
  2005年   290篇
  2004年   248篇
  2003年   215篇
  2002年   191篇
  2001年   96篇
  2000年   110篇
  1999年   88篇
  1998年   53篇
  1997年   38篇
  1996年   27篇
  1995年   32篇
  1993年   24篇
  1992年   88篇
  1991年   52篇
  1990年   62篇
  1989年   54篇
  1988年   55篇
  1987年   54篇
  1986年   48篇
  1985年   41篇
  1984年   36篇
  1983年   27篇
  1981年   25篇
  1980年   24篇
  1979年   46篇
  1978年   27篇
  1977年   33篇
  1975年   26篇
  1974年   30篇
  1973年   41篇
  1972年   38篇
  1971年   26篇
排序方式: 共有6649条查询结果,搜索用时 15 毫秒
91.
Post-partum haemorrhage (PPH) is a life-threatening obstetric complication and the leading cause of maternal death. Any bleeding that results in or could result in haemodynamic instability, if untreated, must be considered as PPH. There is no controversy about the need for prevention and treatment of PPH. The keystone of management of PPH entails first, non-invasive and nonsurgical methods and then invasive and surgical methods. However, mortality remains high. Therefore, new advancements in the treatment are most crucial. One such advancement has been the use of recombinant activated factor VII (rFVIIa) in PPH. First used 12 years back in PPH, this universal haemostatic agent has been effectively used in controlling PPH. The best available indicator of rFVIIa efficacy is the arrest of haemorrhage, which is judged by visual evidence and haemodynamic stabilization. It also reduces costs of therapy and the use of blood components in massive PPH. In cases of intractable PPH with no other obvious indications for hysterectomy, administration of rFVIIa should be considered before surgery. We share our experience in a series of cases of PPH, successfully managed using rFVIIa.  相似文献   
92.
93.
94.
95.
Our group has previously found that in silico, mechanical anisotropy may be interrogated by exciting transversely isotropic materials with geometrically asymmetric acoustic radiation force excitations and then monitoring the associated induced displacements in the region of excitation. We now translate acoustic radiation force-based anisotropy assessment to human muscle in vivo and investigate its clinical relevance to monitoring muscle degeneration in Duchenne muscular dystrophy (DMD). Clinical anisotropy assessments were performed using Viscoelastic Response ultrasound, with a degree of anisotropy reflected by the ratios of Viscoelastic Response relative elasticity (RE) or relative viscosity (RV) measured with the asymmetric radiation force oriented parallel versus perpendicular to muscle fiber alignment. In vivo results from rectus femoris and gastrocnemius muscles of boys aged ~7.9–10.4 y indicate that RE and RV anisotropy ratios in rectus femoris muscles of boys with DMD were significantly higher than those of healthy control boys (RE: DMD?=?1.51 ± 0.87, control?=?0.99 ± 0.69, p?=?0.04, Wilcoxon rank sum test; RV: DMD?=?1.04 ± 0.71, control?=?0.74 ± 0.22, p?=?0.02). In the gastrocnemius muscle, only the RV anisotropy ratio was significantly higher in dystrophic than control patients (DMD?=?1.23 ± 0.35, control?=?0.88 ± 0.31, p?=?0.04). In the dystrophic rectus femoris muscle, the RE anisotropy ratio was inversely correlated (slope?=?–0.03/lbf, r?=?–0.43, p?=?0.07, Pearson correlation) with quantitative muscle testing functional output measures but was not correlated with quantitative muscle testing in the dystrophic gastrocnemius. These results suggest that Viscoelastic Response RE and RV measures reflect differences in mechanical anisotropy associated with functional impairment with dystrophic degeneration that are relevant to monitoring DMD clinically.  相似文献   
96.
Objective: The aim of this study is to compare subfoveal choroidal thickness (SFCT) before and after uneventful phacoemulsification using enhanced depth imaging optical coherence tomography (EDI-OCT).Background: Cataract is a major cause of visual impairment in the elderly. Cataract surgery is the most common ophthalmic surgery and is performed simultaneously with glaucoma or vitreous surgery in many cases. However, according to the results in epidemiology studies, cataract surgery is associated with the onset of age-related macular degeneration (AMD) and cataract surgery increases visual acuity in these patients without an increased risk of progression to exudative AMD. Methods: A prospective study was conducted on 53 eyes of 53 patients who had phacoemulsification. Measurements of SFCT were performed preoperatively, 7 days (D7), 1 month (M1), and 3 months (M3) postoperative using the EDI-OCT technique. Central retinal thickness was also measured at the same time. Results: Twenty-seven male (50.9%) and 26 female (49.1%) with a mean age of 56.43 years ± 10.34 (SD) were analyzed. The mean choroidal thickness was 199.9 ± 60.74 µm. It significantly increased to 228.42 ± 59.77 µm at D7, then decreased to 210.78 ± 59.59 µm at M1, and then decreased to 200.63 ± 61 µm at M3. The mean retinal thickness was 260.79 ± 6.12 µm. It significantly increased to 294.09 ± 7.20 µm at D7 and then decreased to 274.70 ± 6.00 µm at M1 and 258.92 ± 5.89 µm at M3. Conclusion: Mean SFCT increased after cataract surgery. The changes in SFCT return to near the baseline after 3 months.  相似文献   
97.
98.
99.
Radioactivity in the soil of a tea garden in the Fatickchari area in Chittagong, Bangladesh, was measured using a high-resolution HPGe detector. The soil samples were collected from depths of up to 20 cm beneath the soil surface. The activity concentrations of naturally occurring 238U and 232Th were observed to be in the range of 27 ± 7 to 53 ± 8 Bq kg−1 and 36 ± 11 to 72 ± 11 Bq kg−1, respectively. The activity concentration of 40K ranged from 201 ± 78 to 672 ± 81 Bq kg−1, and the highest activity of fallout 137Cs observed was 10 ± 1 Bq kg−1. The average activity concentration observed for 238U was 39 ± 8 Bq kg−1, for 232Th was 57 ± 11 Bq kg−1, for 40K was 384 ± 79 Bq kg−1 and for 137Cs was 5 ± 0.5 Bq kg−1. The radiological hazard parameters (representative level index, radium equivalent activity, outdoor and indoor dose rates, outdoor and indoor annual effective dose equivalents, and radiation hazard index) were calculated from the radioactivity in the soil.  相似文献   
100.
Hepatitis C virus(HCV)is a major health burden infecting 170-210 million people worldwide.Additional 3-4millions are newly-infected annually.Prevalence of pediatric infection varies from 0.05%-0.36%in the United States and Europe;up to 1.8%-5.8%in some developing countries.The highest prevalence occurs in Egypt,sub-Saharan Africa,Amazon basin and Mongolia.HCV has been present in some populations for several centuries,notably genotypes 1 and 2 in West Africa.Parenteral anti-schistosomal therapy practiced in the 1960s until the early 1980s had spread HCV infection throughout Egypt.Parenteral acquisition of HCV remains a major route for infection among Egyptian children.Insufficient screening of transfusions,unsterilized injection equipment and re-used needles and syringes continue to be major routes of HCV transmission in developing countries,whereas vertical transmission and adolescent high-risk behaviors(e.g.,injection drug abuse)are the major routes in developed countries.The risk of vertical transmission from an infected mother to her unborn/newborn infant is approximately 5%.Early stages of HCV infection in children do not lead to marked impairment in the quality of life nor to cognitive,behavioral or emotional dysfunction;however,caregiver stress and family system strain may occur.HCV slowly progresses to serious complications as cirrhosis(1%-2%)and hepatocellular carcinoma(HCC)especially in the presence of risk factors as hemolytic anemias,obesity,treated malignancy,and concomitant human immune deficiency and/or hepatitis B virus co-infection.HCV vaccine remains elusive to date.Understanding the immune mechanisms in patients who successfully cleared the infection is essential for vaccine development.The pediatric standard of care treatment consists of pegylated interferon-α2a or b plus ribavirin for 24-48 wk.The new oral direct acting antivirals,approved for adults,need further evaluation in children.Sustained virologic response varies depending on the viral load,genotype,duration of infection,degree of am  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