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   8779篇
  免费   360篇
  国内免费   60篇
耳鼻咽喉   89篇
儿科学   79篇
妇产科学   70篇
基础医学   1011篇
口腔科学   291篇
临床医学   710篇
内科学   1857篇
皮肤病学   272篇
神经病学   572篇
特种医学   477篇
外科学   1670篇
综合类   50篇
一般理论   1篇
预防医学   391篇
眼科学   86篇
药学   704篇
中国医学   28篇
肿瘤学   841篇
  2023年   40篇
  2022年   91篇
  2021年   153篇
  2020年   93篇
  2019年   124篇
  2018年   164篇
  2017年   107篇
  2016年   145篇
  2015年   143篇
  2014年   191篇
  2013年   237篇
  2012年   396篇
  2011年   451篇
  2010年   262篇
  2009年   191篇
  2008年   364篇
  2007年   385篇
  2006年   382篇
  2005年   363篇
  2004年   357篇
  2003年   359篇
  2002年   330篇
  2001年   299篇
  2000年   312篇
  1999年   303篇
  1998年   136篇
  1997年   71篇
  1996年   72篇
  1995年   85篇
  1994年   65篇
  1993年   52篇
  1992年   222篇
  1991年   199篇
  1990年   218篇
  1989年   221篇
  1988年   178篇
  1987年   192篇
  1986年   161篇
  1985年   156篇
  1984年   101篇
  1983年   83篇
  1982年   40篇
  1981年   50篇
  1979年   97篇
  1978年   41篇
  1977年   52篇
  1974年   47篇
  1971年   40篇
  1969年   45篇
  1968年   40篇
排序方式: 共有9199条查询结果,搜索用时 12 毫秒
21.
22.
The risk of cerebral infarction (CI) in an individual is dependent on the interplay between genetic risk factors and environmental influences. Binding of thromboxane A2 (TXA2) to its receptor (TP) modulates thrombosis/hemostasis and plays a significant role in the pathogenesis of CI. The aim of the present study was to investigate the relationship between human TP gene single nucleotide polymorphisms (SNPs) and haplotypes and CI in a Japanese population. A genetic association study was performed in 194 CI patients and 365 non-CI subjects by specifically characterizing 6 SNPs in the human TP gene (rs2271875, rs768963, rs2238634, rs11085026, rs4523 and rs4806942). Analysis demonstrated that there were significant differences in the overall distribution of genotypes and dominant or recessive models of rs2271875 and rs768963 between the CI and the non-CI groups. Multiple logistic regression analysis revealed that the C allele of rs768963 was significantly associated with CI (p = 0.029), even after adjusting for confounding factors (odds ratio: 2.41). Further, the C-T-C haplotype of rs768963-rs2238634-rs4806942 was significantly more frequent in the CI group (23.0%) than in the non-CI group (17.7%). These results suggest that specific SNPs and haplotypes may have utility as genetic markers for the risk of CI and that TP or a neighboring gene is associated with the increased susceptibility to CI.  相似文献   
23.
We assessed the relations of visual hallucinations (VH) to cardiovascular autonomic dysfunction in patients with Parkinson's disease (PD). The subjects were 37 patients without VH (VH(-)) and 31 with VH (VH(+)). Autonomic function was evaluated on the basis of cardiac 123-radioiodinated metaiodobenzylguanidine (123I-MIBG) uptake and hemodynamic testing with Valsalva maneuver. Systolic blood pressure (SBP) and plasma norepinephrine concentrations (NE) were measured by tilt-table testing. 123I-MIBG uptake was lower in VH(+) than VH(-). Hemodynamic studies showed that VH(-) had only cardiac sympathetic and parasympathetic dysfunction, while VH(+) additionally had reduced vasomotor sympathetic functions. The fall in SBP during tilt-table testing was greater in VH(+) than VH(-). NE and its difference in the supine and upright positions were decreased in VH(+). We conclude that cardiac and vasomotor sympathetic dysfunction is more severe in VH(+) than in VH(-). Severe dysfunction in PD with VH is probably attributed to Lewy-body lesions or neuronal loss in sympathetic ganglia, the central autonomic system, or both.  相似文献   
24.
Prostaglandin E1 (PGE1) has several potential therapeutic effects, including cytoprotection, vasodilation, and inhibition of platelet aggregation. This study investigates the protective action of PGE1 against hepatic ischemia/reperfusion injury in vivo using a complementary DNA microarray. PGE1 or saline was continuously administered intravenously to mice in which the left lobe of the liver was made ischemic for 30 minutes and then reperfused. Livers were harvested 0, 10, and 30 minutes postreperfusion. Messenger RNA was extracted, and the samples were labeled with two different fluorescent dyes and hybridized to the RIKEN set of 18,816 full-length enriched mouse complementary DNA microarrays. Serum alanine aminotransferase and aspartate aminotransferase levels at 180 minutes postreperfusion were significantly lower in the PGE1-treated group than in the saline-treated group. The cDNA microarray analysis revealed that the genes encoding heat-shock protein (HSP) 70, glucose-regulated protein 78, HSP86, and glutathione S-transferase were upregulated at the end of the ischemic period (0 minutes postreperfusion) in the PGE1 group. Our results suggested that PGE1 induces HSPs immediately after ischemia reperfusion. HSPs might therefore play an important role in the protective effects of PGE1 against ischemia/reperfusion injury of the liver.  相似文献   
25.
We performed myocardial revascularization with bilateral internal mammary arteries in eight children for coronary artery complications consequent to Kawasaki disease. Subjects included seven boys and one girl, ranging in age from 3 to 13 years (mean age, 8.3 +/- 3.4 years). The body surface area ranged from 0.65 to 1.65 m2 (average, 1.08 +/- 0.35 m2). Three patients had a previous myocardial infarction. The right internal mammary artery was anastomosed to the right coronary artery and the left internal mammary artery was sutured to the left anterior descending artery in all patients. The patients received an average of 2.4 grafts. Magnifying loupes of 3.5 X were used for anastomosis with 8-0 monofilament polypropylene sutures. Subjects were followed up from 12 to 38 months (23 +/- 10.8 months) after operation. All were doing well with no recurrence of angina, and body development was normal, including the sternum and thorax according to chest x-ray films and computed tomography of the chest. Patency of the bilateral internal mammary arteries was 100% in the early (within 1 month) postoperative period and remained so in the late (over 1 year) postoperative period. Anastomotic junctions between the internal mammary artery and the coronary artery developed well angiographically in the late postoperative period. The internal mammary artery is the graft of choice for pediatric myocardial revascularization because of its excellent long-term patency and growth potential. Bilateral internal mammary arteries should be used whenever indicated, and the use of bilateral internal mammary arteries did not adversely influence chest wall development in the children.  相似文献   
26.
Forty-nine patients with 63 cystic thyroid masses who had undergone preoperative sonography were retrospectively reviewed. 52 lesions (83%) were benign and others (17%) were malignant. Among various sonographic findings of cystic thyroid masses, oval cystic lesions with polyp or dome like solid component projecting into the lumen were all diagnosed adenomatous goiter. Irregular cystic structures with more than 2 cm finger like pedunculated mass extended into and/or out of the lumen were all diagnosed papillary carcinoma. Small oval cysts (less than or equal to 1 cm) with strong echo were all diagnosed colloid goiter. The other sonographic type of cystic thyroid masses had somewhat malignancy (12-30%), not having characteristics which differentiate benign from malignant lesions. Pathologic findings of malignant lesions showed that cancer cells existed rather in pericystic portion than in cyst wall except for finger like solid component projecting into the lumen which was papillary carcinoma itself. Ultrasonically guided needle biopsy should be performed to get samples of above portions.  相似文献   
27.
Currently, heterogeneity is the word to describe any inhomogeneous phenomenon observed in the ever changing living creatures. Myocardial function is dynamic in nature which is a summation of many inhomogeneous components. In fact, heterogenic phenomenon has been observed both at cellular and at ventricular levels during myocardial contraction and relaxation. However, this heterogenic behavior of myocardial activities serves as a source of monitoring parameters by which we can grasp what is happening in the patient. Reliance on only one of those parameters would lead to a wrong diagnosis and judgement in the heterogenic world. We, therefore, need to integrate those parameters to form more realistic image about patient's status. We have to have a cut off point to divide what is right and what is wrong. Although the truth may not be reached eventually from heterogeneous informations, an appropriate method to integrate informations in the heterogenic world will aid us to come closer to the reality.  相似文献   
28.
Summary A human glioma cell line (YKG1), which was positively identified for glial fibrillary acidic (GFA) and S-100 proteins, was established from a surgical specimen of a patient with glioblastoma. Chromosome analysis of the cells revealed a homogeneously staining region (HSR) on a marker chromosome. The assay for transforming growth factors (TGFs) in the conditioned medium of the cell line revealed that it contained high levels of - and -type TGFs, which might regulate the growth of glioblastoma and influence on the peritumoral tissues.  相似文献   
29.
Calcified stenotic aortic valve are usually replaced by the artificial valve. Recently, we are trying to decalcify the calcification of the aortic valve by ultrasonic energy. This case report reviewed a small physique, 47 year old female, who had the calcified stenotic bicuspid aortic valve and the narrow aortic valve ring (18 mm diameter). The ultrasonic decalcification was performed by the ultrasonic surgical instrument, SUS-201D (ALOKA), ultrasonic energy output range from 25% to 45%. After the ultrasonic decalcification, the movability of the aortic cusps were improved and the aortic opening was enlarged. The systolic pressure gradient across the aortic valve was improved from 100 mmHg to 20 mmHg. This method "ultrasonic decalcification" is very useful technique for the repair of the calcified aortic valve stenosis.  相似文献   
30.
A new indole alkaloid glucoside, named palicoside, has been isolated from the leaves of PALICOUREA MARCGRAVII (Rubiaceae) collected in Brazil. The structure was established by spectroscopic methods and its chemical conversion to strictosamide.  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