全文获取类型
收费全文 | 92828篇 |
免费 | 6830篇 |
国内免费 | 571篇 |
专业分类
耳鼻咽喉 | 1069篇 |
儿科学 | 2432篇 |
妇产科学 | 2030篇 |
基础医学 | 11733篇 |
口腔科学 | 1528篇 |
临床医学 | 9262篇 |
内科学 | 19308篇 |
皮肤病学 | 1542篇 |
神经病学 | 7932篇 |
特种医学 | 3097篇 |
外国民族医学 | 4篇 |
外科学 | 14609篇 |
综合类 | 1979篇 |
现状与发展 | 1篇 |
一般理论 | 101篇 |
预防医学 | 7043篇 |
眼科学 | 2753篇 |
药学 | 6227篇 |
中国医学 | 369篇 |
肿瘤学 | 7210篇 |
出版年
2023年 | 480篇 |
2022年 | 928篇 |
2021年 | 1943篇 |
2020年 | 1163篇 |
2019年 | 1718篇 |
2018年 | 2144篇 |
2017年 | 1546篇 |
2016年 | 1750篇 |
2015年 | 2014篇 |
2014年 | 2986篇 |
2013年 | 4048篇 |
2012年 | 5872篇 |
2011年 | 6302篇 |
2010年 | 3578篇 |
2009年 | 3236篇 |
2008年 | 5387篇 |
2007年 | 5644篇 |
2006年 | 5621篇 |
2005年 | 5651篇 |
2004年 | 5345篇 |
2003年 | 4919篇 |
2002年 | 4677篇 |
2001年 | 1590篇 |
2000年 | 1406篇 |
1999年 | 1468篇 |
1998年 | 1098篇 |
1997年 | 893篇 |
1996年 | 810篇 |
1995年 | 732篇 |
1994年 | 668篇 |
1993年 | 623篇 |
1992年 | 806篇 |
1991年 | 801篇 |
1990年 | 715篇 |
1989年 | 694篇 |
1988年 | 630篇 |
1987年 | 638篇 |
1986年 | 569篇 |
1985年 | 574篇 |
1984年 | 671篇 |
1983年 | 543篇 |
1982年 | 616篇 |
1981年 | 593篇 |
1980年 | 582篇 |
1979年 | 388篇 |
1978年 | 380篇 |
1977年 | 356篇 |
1976年 | 297篇 |
1975年 | 294篇 |
1974年 | 296篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
93.
94.
95.
Philip F. Giampietro MD PhD Margaret G. E. Peterson PhD Robert Schneider MD Jessica G. Davis MD Stephen W. Burke MD Oheneba Boachie-Adjei MD Charles M. Mueller PhD RD Cathleen L. Raggio MD 《HSS journal》2007,3(1):89-92
Reduced bone mineral density (BMD) was sporadically reported in patients with Marfan syndrome. This may or may not place the
Marfan patient at increased risk for bone fracture. In comparing the BMDs of our patients with those reported in the literature,
it seemed that agreement between values, and hence the degree of osteoporosis or osteopenia reported, was dependent on the
instrumentation used. The objective of this study was to statistically assess this impression. Bone mineral density measurements
from our previously published study of 30 adults with Marfan syndrome performed on a Lunar DPXL machine were compared with
studies published between 1993–2000 measured using either Lunar or Hologic bone densitometry instruments. The differences
of our measurements compared with those made on other Lunar machines were not statistically significant, but did differ significantly
with published results from Hologic machines (P < 0.001). Before progress can be made in the assessment of BMD and fracture risk in Marfan patients and in the evidence-based
orthopedic management of these patients, standardization of instrumental bone density determinations will be required along
with considerations of height, obesity, age, and sex. 相似文献
96.
97.
Hung-Fat Tse Sukumaran Thambar Yok-Lam Kwong Philip Rowlings Greg Bellamy Jane McCrohon Paul Thomas Bruce Bastian John K F Chan Gladys Lo Chi-Lai Ho Wing-Sze Chan Raymond Y Kwong Anthony Parker Thomas H Hauser Jenny Chan Daniel Y T Fong Chu-Pak Lau 《European heart journal》2007,28(24):2998-3005
AIMS: Experimental studies have demonstrated that bone marrow (BM) cells can induce angiogenesis in ischaemic myocardium. Recently, several non-randomized pilot studies have also suggested that direct BM cells implantation appears to be feasible and safe in patients with severe coronary artery diseases (CAD). METHODS AND RESULTS: We performed a randomized, blinded, and placebo-controlled trial in 28 CAD patients. After BM harvesting, we assigned patients to receive low dose (1 x 10(6) cells/0.1 mL, n = 9), high dose (2 x 10(6) cells/0.1 mL, n = 10) autologous BM cells or control (0.1 mL autologous plasma/injection, n = 9) catheter-based direct endomyocardial injection as guided by electromechanical mapping. Our primary endpoint was the increase in exercise treadmill time and our secondary endpoints were changes in Canadian Cardiovascular Society (CCS) and New York Heart Association (NYHA) class, and myocardial perfusion and left ventricular ejection fraction (LVEF) assessed by single-photon emission computed tomography and magnetic resonance imaging, respectively. A total 422 injections (mean 14.6 +/- 0.7 per patient) were successfully performed at 41 targeted ischaemic regions without any acute complication. Baseline exercise treadmill time was 439 +/- 182 s in controls and 393 +/- 136 s in BM-treated patients, and changed after 6 months to 383 +/- 223s and 464 +/- 196 s [BM treatment effect +0.43 log seconds (+53%), 95% CI 0.11-0.74, P = 0.014]. Compared with placebo injection, BM implantation was associated with a significant increase in LVEF (BM treatment effect +5.4%, 95% CI 0.4-10.3, P = 0.044) and a lower NYHA class (odds ratio for treatment effect 0.12, 95% CI 0.02-0.73, P = 0.021) after 6 months, but CCS reduced similarly in both groups. We observed no acute or long-term complications, including ventricular arrhythmia, myocardial damage, or development of intramyocardial tumour or calcification associated with BM implantation. CONCLUSION: Direct endomyocardial implantation of autologous BM cells significantly improved exercise time, LVEF, and NYHA functional class in patients with severe CAD who failed conventional therapy. 相似文献
98.
BACKGROUND: Previous studies with cystic fibrosis transmembrane conductance regulator (CFTR) DeltaF508 mice indicate that estrogen levels may play a role in the occurrence or severity of CF-associated liver disease. However, the underlying mechanisms of liver disease in CF are poorly understood. METHODS: The levels of SULT1E1 (estrogen sulfotransferase) were measured in livers of control and CFTR-knockout (KO) mice. The impact of increased SULT1E1 activity on hepatic protein expression was assessed by immunoblot and MALDI mass spectrometric analysis. RESULTS: SULT1E1 expression was significantly elevated in livers of several CFTR-KO mice. SULT1E1 and CFTR were specifically detected in hepatocytes and cholangiocytes, respectively. Elevated SULT1E1 activity may result in lower levels of free beta-estradiol thereby altering estrogen-responsive hepatic protein expression. Estrogen receptors (ER)-alpha and beta were differentially regulated in CFTR-KO and CFTR-DeltaF508 mice. ERalpha expression was reduced in mice with high SULT1E1 activity. Glutathione S-transferase-P1 and carbonic anhydrase III were significantly decreased in CFTR (-/-) mice with high SULT1E1 activity. Furthermore, cytochrome P450 2B9, also estrogen regulated, was significantly induced in the livers of CFTR (-/-) mice with high SULT1E1 activity. CONCLUSIONS: Elevated SULT1E1 levels and associated alterations in estrogen-regulated hepatic protein expression may play an important role in CF liver disease. 相似文献
99.
Mao-Sheng Ran Meng-Ze Xiang Jie Li Jian Huang Eric Yu-Hai Chen Cecilia Lai-Wan Chan Yeates Conwell 《Archives of Suicide Research》2007,11(1):119-127
The aim of this study was to compare the demographic and clinical characteristics of individuals with affective disorders who had attempted suicide at some time in their lives and those who had not made a suicide attempt. In a Chinese rural community, individuals with suicide attempt (N = 30) and those without suicide attempt (N = 166) were assessed with Present State Examination (PSE). Attempters had a significantly higher level of family economic status, higher rate of lifetime depressed mood and hopelessness, and delusions than nonattempters. The logistic regression models also indicated that depressed mood and hopelessness were the most important predictors of suicide attempts. No significant difference in treatment condition was found between attempters and non-attempters. Early identification and interventions focusing on reducing depressed mood, hopelessness, and controlling psychotic symptoms may be helpful in reducing the risk of suicide attempts among individuals with affective disorders residing in the community. 相似文献
100.