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   37340篇
  免费   2941篇
  国内免费   354篇
耳鼻咽喉   413篇
儿科学   1001篇
妇产科学   967篇
基础医学   4762篇
口腔科学   624篇
临床医学   3878篇
内科学   7934篇
皮肤病学   837篇
神经病学   2621篇
特种医学   1220篇
外科学   5210篇
综合类   1187篇
一般理论   32篇
预防医学   2127篇
眼科学   1605篇
药学   2826篇
中国医学   308篇
肿瘤学   3083篇
  2023年   259篇
  2022年   437篇
  2021年   1018篇
  2020年   645篇
  2019年   842篇
  2018年   1065篇
  2017年   794篇
  2016年   916篇
  2015年   1084篇
  2014年   1425篇
  2013年   1732篇
  2012年   2460篇
  2011年   2595篇
  2010年   1470篇
  2009年   1293篇
  2008年   2007篇
  2007年   2083篇
  2006年   2080篇
  2005年   1987篇
  2004年   1777篇
  2003年   1644篇
  2002年   1483篇
  2001年   1154篇
  2000年   1082篇
  1999年   933篇
  1998年   370篇
  1997年   273篇
  1996年   254篇
  1995年   203篇
  1994年   204篇
  1993年   194篇
  1992年   478篇
  1991年   467篇
  1990年   437篇
  1989年   416篇
  1988年   355篇
  1987年   374篇
  1986年   324篇
  1985年   286篇
  1984年   212篇
  1983年   159篇
  1982年   103篇
  1981年   89篇
  1980年   98篇
  1979年   152篇
  1978年   98篇
  1977年   79篇
  1976年   83篇
  1975年   86篇
  1972年   81篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
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   
42.
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   
43.
44.
Klippel-Feil syndrome (KFS) is a heterogeneous entity, characterized by specific congenital anomalies of segmentation of the cervical spine. We report a case of KFS plus atretic meningocele in one identical twin and anencephaly in the other. These identical twins were both male with no chromosome defect. One of them had anencephaly diagnosed at the gestational age of 17 weeks and died soon after birth, whereas the co-twin had KFS with multiple congenital anomalies including short neck with low hairline, occipital atretic meningocele, butterfly vertebrae, hemivertebrae, cervico-thoracic scoliosis, left thumb preaxial polydactyly, and right undescended testis. He received rehabilitation during infancy and could walk at the age of 15 months. Both of these infants had preaxial polydactyly, which is an uncommon anomaly associated with KFS. In conclusion, iniencephaly and anencephaly are probably the extreme manifestations of KFS rather than different dysraphisms. Prompt clinical suspicion with early diagnostic imaging for spine lesions and occult opening of neural tube is mandatory for further intervention and rehabilitation.  相似文献   
45.
46.
Many people die in emergency departments (EDs) across the United States from sudden illnesses or injuries, an exacerbation of a chronic disease, or a terminal illness. Frequently, patients and families come to the ED seeking lifesaving or life-prolonging treatment. In addition, the ED is a place of transition-patients usually are transferred to an inpatient unit, transferred to another hospital, or discharged home. Rarely are patients supposed to remain in the ED. Currently, there is an increasing amount of literature related to end-of-life care. However, these end-of-life care models are based on chronic disease trajectories and have difficulty accommodating sudden-death trajectories common in the ED. There is very little information about end-of-life care in the ED. This article explores ED culture and characteristics, and examines the applicability of current end-of-life care models.  相似文献   
47.
OBJECTIVE: The aim of this study was to determine whether the survival of patients with untreated synchronous liver metastases after resection of a colorectal cancer was associated with any features of the primary tumour. METHODS: Information for 398 consecutive patients with unresected liver metastases in the period 1971-2001 was examined by multivariate survival analysis. RESULTS: Of 19 clinical and pathological variables considered, survival was independently associated only with residual tumour in a line of resection (hazard ratio (HR) 1.95), venous invasion (HR 1.87), right colonic tumour (HR 1.68), lymph node metastasis (HR 1.54), and extra-hepatic metastasis (HR 1.16); 8.3% of patients had none of these adverse features. Their 2-year overall survival rate was 39.2%, compared with only 16.5% (P < 0.001) in those with one or more adverse features. CONCLUSIONS: These findings may assist in selecting patients most likely to benefit from treatment of hepatic metastases and in counselling patients and their relatives.  相似文献   
48.
The appearance of an acute effusion in a well-pneumatized temporal bone directs attention to the nasopharynx and skull base. Two patients are described in whom dehiscence of the temporomandibular joint allowed herniation of the contents of the joint posteromedically, where they obstructed the middle ear entrance of the eustachian tube, the protympanum. This is, to the authors' knowledge, a previously unreported cause of an acute middle ear and mastoid effusion.  相似文献   
49.
The clinical presentation and the biochemical and molecular genetic findings are described in a 13 year old Chinese boy with MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes). The diagnosis was initially suspected because of the characteristic clinical features and the strong family history of convulsions. Using polymerase chain reaction—restriction enzyme analysis, the heteroplasmic nt3243 A→G mutation in mtDNA of peripheral blood leucocytes and a muscle sample was demonstrated. The oligosymptomatic relatives were then screened by this method and the degree of heteroplasmy was analysed. This appears to be the first report of a MELAS family in Hong Kong with this described mutation. Molecular genetic techniques are advantageous in the diagnosis of MELAS.  相似文献   
50.
应用双光子及单光子吸收测定技术,检测了92名出生3d内的新生儿骨矿质含量,其中巨大儿30名,正常体重儿32名,低出生体重儿30名,其孕龄分别是40.1±0.7、39.1±1.5和37.4±1.2孕周。结果表明,巨大儿、正常体重儿、低出生体重儿的全身骨矿质含量分别是101.6±28.8、85.2±19.8、59.9±27.2g/cm2,巨大儿骨矿质含量最高,正常体重儿次之,低出生体重儿最低,差异有显著性(P<0.01)。颅骨、肱骨、股骨的骨矿质含量与全身的骨矿质含量有高度的相关性,相关系数分别是0.943、0.879和0.745(P<0.01)。全身的骨矿质含量与出生体重、孕龄及头围有高度相关性,相关系数分别是0.755、0.596和0.556(P<0.01)。提示颅骨、肱骨及股骨的任一部位均可代表全身的骨矿质含量,肱骨是确定全身骨矿质含量较好的部位,新生儿骨矿质含量受出生体重、孕龄及头围的影响较大。  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