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   2846篇
  免费   123篇
  国内免费   16篇
耳鼻咽喉   58篇
儿科学   121篇
妇产科学   111篇
基础医学   307篇
口腔科学   74篇
临床医学   243篇
内科学   536篇
皮肤病学   87篇
神经病学   184篇
特种医学   72篇
外科学   547篇
综合类   40篇
一般理论   2篇
预防医学   113篇
眼科学   63篇
药学   236篇
中国医学   11篇
肿瘤学   180篇
  2024年   5篇
  2023年   28篇
  2022年   77篇
  2021年   144篇
  2020年   71篇
  2019年   119篇
  2018年   109篇
  2017年   80篇
  2016年   92篇
  2015年   111篇
  2014年   149篇
  2013年   158篇
  2012年   279篇
  2011年   301篇
  2010年   147篇
  2009年   113篇
  2008年   174篇
  2007年   123篇
  2006年   144篇
  2005年   142篇
  2004年   116篇
  2003年   91篇
  2002年   66篇
  2001年   14篇
  2000年   12篇
  1999年   11篇
  1998年   11篇
  1997年   5篇
  1996年   3篇
  1995年   5篇
  1994年   10篇
  1992年   2篇
  1991年   9篇
  1990年   2篇
  1989年   4篇
  1988年   4篇
  1986年   5篇
  1985年   3篇
  1984年   4篇
  1983年   2篇
  1982年   7篇
  1981年   3篇
  1979年   2篇
  1978年   4篇
  1975年   2篇
  1974年   2篇
  1972年   2篇
  1971年   3篇
  1970年   4篇
  1966年   3篇
排序方式: 共有2985条查询结果,搜索用时 15 毫秒
31.
Multichannel auditory brainstem implants (ABI) are currently indicated for patients with neurofibromatosis type II (NF2) involving both vestibulocochlear nerves. The ABI helps bypass the damaged cochlear nerves and restores a level of auditory sensation via the electrical stimulation of the cochlear nucleus. The implant is usually placed in the lateral recess of the fourth ventricle at the time of tumor resection to stimulate the cochlear nucleus. We report a case of ABI done on a 15-year-old girl with bilateral vestibular schwannomas.  相似文献   
32.
Several 1-(substituted phenoxy)-3-{[4-(4-trifluoromethyl) phenoxy] piperidin-1-yl} propan-2-ols (str.II) were prepared in a six-step reaction sequence starting from methylamine and ethyl acrylate and evaluated for antidepressant activity. The compounds were fully characterized by spectral and elemental analyses, and were tested for their effect on gross behavior, antireserpine and anorexigenic activity. No effect was observed on gross behavior and some of them showed fluoxetine like antireserpine and anorexigenic activity.  相似文献   
33.
The binding studies of Co(III) and Ru(II) polypyridyl complexes with dsDNA were carried out by molecular modeling studies to identify the binding interactions. The 3D structures of the metal complexes [Ru(phen)2ippip]2+ (RP-ippip), [Co(phen)2ippip]3+ (CP-ippip), [Ru(bpy)2ippip]2+ (RB-ippip), and [Co(bpy)2ippip]3+ (CB-ippip), where ippip = 4-(isopropylbenzaldehyde)imidazo[4,5-f][1,10] phenanthroline, phen = 1,10-phenanthroline, and bpy = bypyridine, were simulated using molecular dynamic simulations for stable conformers. The energy-minimized 3D structures of metal complexes were docked to the double-stranded dodecamer 5′-D(*AP * CP * CP * GP * AP * CP * GP * TP * CP * GP * GP * T)-3′. The aromatic ligand, ippip, facilitates the binding of the metal complex with DNA through intercalation. The effect of ancillary ligands, phen and bpy, was investigated. The ancillary ligands were found to be involved in bond formation with the phosphate backbone of nucleotide base pairs in metal complex–DNA docked complex. The significant interactions of metal complexes in the major groove of DNA are the prerequisite features of the metal complexes to be considered as DNA-intercalator. The molecular docking data are well substantiated by the available experimental data. The modeling results should extend knowledge about the nature of binding of these complexes with DNA.  相似文献   
34.
Aim To compare American Diabetes Association and International Expert Committee recommended cut‐off values of HbA1c for detecting the presence of pre‐diabetes against plasma glucose values obtained from oral glucose tolerance tests in Asian Indians. Methods A cross‐sectional randomly sampled population survey involving 2368 adults, aged ≥ 20 years. HbA1c was measured on a Bio‐Rad 10 system in 1972 subjects. Results Of the 1972 subjects studied, 329 were detected to have pre‐diabetes based on isolated impaired fasting glucose in 125 subjects (6.3%), isolated impaired glucose tolerance in 141 subjects (7.1%) and the presence of both in 63 subjects (3.2%). The HbA1c cut‐off of 34 mmol/mol (5.7%), as recommended by the American Diabetes Association for detecting the presence of pre‐diabetes, showed sensitivity of 62%, specificity 77%, with a positive predictive value of 34.7%, a negative predictive value of 89.5% and accuracy of 67.8%; whereas the HbA1c cut‐off recommended by the International Expert Committee of 42 mmol/mol (6%) had a sensitivity of 36%, specificity of 90%, positive predictive value of 42.7%, negative predictive of 85.4% and an accuracy of 77%. However, both these HbA1c cut‐offs underdiagnosed the presence of pre‐diabetes in 38 and 64% of these subjects, respectively. Conclusions The American Diabetes Association and the International Expert Committee recommended HbA1c cut‐off values and oral glucose tolerance tests identify different pre‐diabetes cohorts. Long‐term prospective studies are required to define the usefulness of one over the other.  相似文献   
35.
Adaptive optics is a relatively new tool that is available to ophthalmologists for study of cellular level details. In addition to the axial resolution provided by the spectral-domain optical coherence tomography, adaptive optics provides an excellent lateral resolution, enabling visualization of the photoreceptors, blood vessels and details of the optic nerve head. We attempt a mini review of the current role of adaptive optics in retinal imaging. PubMed search was performed with key words Adaptive optics OR Retina OR Retinal imaging. Conference abstracts were searched from the Association for Research in Vision and Ophthalmology (ARVO) and American Academy of Ophthalmology (AAO) meetings. In total, 261 relevant publications and 389 conference abstracts were identified.  相似文献   
36.
Epidemiologic findings suggest that lipids and alteration in lipid metabolizing protein/gene may contribute to the development of neurodegenerative disorders. The aim of the current study was to determine the serum lipid levels and genetic variation in two lipid metabolizing genes, low-density lipoprotein receptor-related protein-associated protein (LRPAP1) and apolipoprotein E (APOE) gene in Parkinson’s disease (PD). Based on well-defined inclusion and exclusion criteria, this study included 70 patients with PD and 100 age-matched controls. LRPAP1 and APOE gene polymorphism were analyzed by polymerase chain reaction and restriction fragment length polymorphism, respectively. Fasting serum lipid levels were determined using an autoanalyser. The logistic regression analysis showed that high levels of serum cholesterol [odds ratio (OR) = 1.101, 95 % confidence interval (CI95%) = 1.067–1.135], LRPAP1 I allelic variant alone (OR = 2.766, CI95% = 1.137–6.752) and in combination with APOE ε4 allelic variant (OR = 4.187, CI95% = 1.621–10.82) were significantly associated with increase in PD risk. Apart from that, the high levels of LDL cholesterol appears to have a protective role (OR = 0.931, CI95% = 0.897–0.966) against PD. The LRPAP1 I allelic variant may be considered a candidate gene for PD, predominantly in patients having the APOE ε4 allelic variant.  相似文献   
37.
Abstract: Scalene muscle injections are used to confirm the diagnosis of neurogenic thoracic outlet syndrome and predict the response of patients to surgery. We performed a retrospective study to determine if relief of pain was related to brachial plexus blockade in these patients. Methods: We reviewed the charts of 12 patients who had anterior and middle scalene muscle injections, for neurogenic thoracic outlet syndrome, between April 2009 and September 2010. The injections were performed under ultrasound guidance wherein 2 to 5 mL of 0.25% bupivacaine was injected into the belly of the anterior and scalene muscles. The following were noted: (1) sites of preprocedure pain; (2) volume injected into each of the anterior and middle scalene muscles; (3) presence of numbness after injection; and (4) presence and duration of pain relief. Results: All 12 patients had relief of their pain. Six of the twelve patients developed numbness, which ranged from blockade of the C4‐5, C6‐7, and C4‐T1 dermatomes. In the patients who developed numbness, there was no relationship between the duration of numbness and the duration of pain relief or the location of numbness and the location of pain relief. Conclusions: The relief from scalene muscle injections in patients with neurogenic thoracic outlet syndrome is not related to blockade of the brachial plexus. ?  相似文献   
38.
Abstract

Positive blood cultures were found in 41 patients on the Spinal Cord Injury Service at the Milwaukee VAMC during the period of July, 1980 to December, 1985 giving an incidence of bacteremia of 1.3%. Mortality rate was 17%. Most common pathogens were E. Coli, Proteus mirabilis, Serratia marcescens and Staphylococcus aureus. A review of 29 available charts revealed genitourinary and respiratory tracts as the most common sources of infection (72.4% and 10.3% respectively). Other sources of infection were skin, postoperative, intravenous catheter site and cellulitis. Initial febrile response was seen in 93.1% of patients with 48.1% having temperature greater than 38.3°C. Hypotension (blood pressure less than 90/50 mm Hg) was noted in five out of the 29 (17.1%) patients. Clinical diagnosis of disseminated intravascular coagulation was made in two out of the 29 (6.9%) patients. Underlying risk factors were poor nutrition, respirator dependency, indwelling Foley catheters and manipulative procedures. Incidence and mortality rates are similar to the non-SCI population as reported elsewhere. The risk factors are different; therefore preventive management is extremely important.  相似文献   
39.
This report and images describe a case of atrial flutter with 2:1 conduction pattern in a 3 year-old male with d-TGA, ASD, and VSD status-post repair, which was demonstrated by M-mode echocardiography.  相似文献   
40.

1 Background and aims

Right ventricular pacing may lead to heart failure (HF). Upgrades from pacemakers to cardiac resynchronization therapy (CRT) were excluded from most randomized, controlled trials. We sought to determine the long‐term outcomes of upgrading from pacemakers to CRT with (CRT‐D) or without (CRT‐P) defibrillation in patients with no history of sustained ventricular arrhythmias.

2 Methods and results

In this observational study, clinical events were quantified in relation to the type of implant (de novo or upgrade) and device type at upgrade (CRT‐P or CRT‐D). Patients underwent CRT implantation (n = 1,545; 1,314 [85%] de novo implants and 231 [15%] upgrades) over a median of 4.6 years [interquartile range: 2.4–7.0]. In analyses of crude event rates, upgrades had a higher total mortality (adjusted hazard ratio [aHR]: 1.33; 95% confidence interval [CI] 0.10–1.61), a higher total mortality or HF hospitalization (aHR: 1.26; 95% CI 1.05–1.51), but similar mortality or hospitalization for major adverse cardiac events (MACEs, aHR: 1.15; 95% CI 0.96–1.38). No group differences emerged in any of these endpoints after propensity score matching. After inverse probability weighting in upgrades, total mortality (HR: 0.55; 95% CI 0.36–0.73), total mortality or HF hospitalization (HR: 0.56; 95% CI 0.34–0.79), and total mortality or hospitalization for MACEs (HR: 0.61; 95% CI 0.40–0.82) were lower after CRT‐D than after CRT‐P.

3 Conclusion

Upgrading from pacemakers to CRT was associated with a similar long‐term risk of mortality and morbidity to de novo CRT. After upgrade, CRT‐D was associated with a lower mortality than CRT‐P.  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