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   5958篇
  免费   303篇
  国内免费   14篇
耳鼻咽喉   68篇
儿科学   335篇
妇产科学   261篇
基础医学   622篇
口腔科学   332篇
临床医学   406篇
内科学   1116篇
皮肤病学   105篇
神经病学   370篇
特种医学   239篇
外科学   807篇
综合类   108篇
一般理论   2篇
预防医学   324篇
眼科学   331篇
药学   499篇
中国医学   50篇
肿瘤学   300篇
  2023年   38篇
  2022年   69篇
  2021年   210篇
  2020年   106篇
  2019年   118篇
  2018年   164篇
  2017年   101篇
  2016年   158篇
  2015年   192篇
  2014年   266篇
  2013年   334篇
  2012年   458篇
  2011年   422篇
  2010年   305篇
  2009年   217篇
  2008年   317篇
  2007年   354篇
  2006年   297篇
  2005年   273篇
  2004年   282篇
  2003年   217篇
  2002年   185篇
  2001年   149篇
  2000年   117篇
  1999年   106篇
  1998年   34篇
  1997年   33篇
  1996年   26篇
  1995年   28篇
  1994年   20篇
  1993年   18篇
  1992年   58篇
  1991年   45篇
  1990年   45篇
  1989年   50篇
  1988年   51篇
  1987年   47篇
  1986年   46篇
  1985年   45篇
  1984年   29篇
  1983年   27篇
  1982年   15篇
  1981年   18篇
  1980年   17篇
  1979年   30篇
  1978年   18篇
  1975年   14篇
  1974年   14篇
  1973年   13篇
  1971年   15篇
排序方式: 共有6275条查询结果,搜索用时 15 毫秒
1.
2.
Purpose:To evaluate the rate of compliance and the reasons for loss to follow-up in Indian patients with diabetic macular edema (DME), age-related macular degeneration (AMD), and retinal vein occlusion (RVO) being treated with anti-vascular endothelial growth factor (VEGF) therapy.Methods:This was a retrospective single-center study. Patients with DME, AMD, or RVO were eligible if they initiated anti-VEGF therapy between January 2013 and December 2017. Patients'' data were obtained from hospital electronic records, including the number of injections received, visits, details of follow-up, missed appointments, and reasons for loss to follow-up (>365 days).Results:A total of 648 patients were eligible for the study, of which 334 (51.54%) patients were lost to follow-up. Overall, 343 (64.96%) were males and the overall mean (SD) age was 66.40 (7.44) years. A total of 376 (58.0%) patients had a history of diabetes and 364 (56.2%) patients had a history of hypertension. Further, 127 (38.0), 112 (33.5), and 95 (28.4) had DME, AMD, and RVO, respectively and were lost to follow-up. The most commonly reported reason for loss to follow-up was “non-affordability” (n = 120; 41.1%) followed by “no improvement in vision” (n = 83; 28.4%). “No improvement in vision” (42.2%) and “non-affordability” (37.5%) were higher among patients with DME. No association was found in gender- and treatment-wise distribution of reasons for loss to follow-up.Conclusion:The results showed that around half of the patients with DME, AMD, and RVO were lost to follow-up to intravitreal anti-VEGF therapy, and the most common factors were “non-affordability” and “no improvement in vision.”  相似文献   
3.
4.
18F-2beta-Carbomethoxy-3beta-(4-chlorophenyl)-8-(2-fluoroethyl)nortropane (18F-FECNT), a PET radioligand for the dopamine transporter (DAT), generates a radiometabolite that enters the rat brain. The aims of this study were to characterize this radiometabolite and to determine whether a similar phenomenon occurs in human and nonhuman primate brains by examining the stability of the apparent distribution volume in DAT-rich (striatum) and DAT-poor (cerebellum) regions of the brain. METHODS: Two rats were infused with 18F-FECNT and sacrificed at 60 min. Extracts of brain and plasma were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometric (LC-MS) techniques. Two human participants and 3 rhesus monkeys were injected with 18F-FECNT and scanned kinetically, with serial arterial blood analysis. RESULTS: At 60 min after the injection of rats, 18F-FECNT accumulated to levels about 7 times higher in the striatum than in the cortex and cerebellum. The radiometabolite was distributed at equal concentrations in all brain regions. The LC-MS techniques identified N-dealkylated FECNT as a major metabolite in the rat brain, and reverse-phase HPLC detected an equivalent amount of radiometabolite eluting with the void volume. The radiometabolite likely was 18F-fluoroacetaldehyde, the product expected from the N-dealkylation of 18F-FECNT, or its oxidation product, 18F-fluoroacetic acid. The distribution volume in the cerebellum increased up to 1.7-fold in humans between 60 and 300 min after injection and 2.0 +/- 0.1-fold (mean +/- SD; n = 3) in nonhuman primates between 60 and 240 min after injection. CONCLUSION: An 18F-fluoroalkyl metabolite of 18F-FECNT originating in the periphery confounded the measurements of DAT in the rat brain with a reference tissue model. Its uniform distribution across brain regions suggests that it has negligible affinity for DAT (i.e., it is an inactive radiometabolite). Consistent with the rodent data, the apparent distribution volume in the cerebellum of both humans and nonhuman primates showed a continual increase at late times after injection, a result that may be attributed to entry of the radiometabolite into the brain. Thus, reference tissue modeling of 18F-FECNT will be prone to more errors than analysis with a measured arterial input function.  相似文献   
5.
OBJECTIVE AND DESIGN: Bacterial products as well as the host airway inflammatory responses contribute to the pathogenesis of Pseudomonas infections. We sought to determine if Pseudomonas elastase (PE) induces mitogen-activated protein (MAP) kinase activity in association with interleukin-8 (IL-8) production by alveolar epithelial cells. METHODS: We utilized Western blot analysis to detect phosphorylation of signaling intermediates and ELISA was used to measure IL-8 production. RESULTS: We found that PE induces phosphorylation of the extracellular signal-regulated (ERK1/2) proteins of the MAPK pathway in A549 epithelial cells. Similar results were obtained using primary cultures of rabbit alveolar type II epithelial cells. PE also enhanced IL-8 production, which was abolished in the presence of the ERK activation inhibitor U0126. CONCLUSIONS: We conclude that PE activates the ERK1/2 arm of the MAPK pathway and that activation of this pathway results in enhanced IL-8 production. The results demonstrate that PE may augment pulmonary inflammation via cellular signaling that regulates expression of IL-8.  相似文献   
6.
We report a case of an intra-articular vascular malformation occurring simultaneously with a ganglion in a knee joint. We believe this to be the first reported case of an intra-articular vascular malformation occurring simultaneously with a ganglion. The malformation was cauterized resulting in resolution of knee pain. We suggest that vascular malformations be considered in the differential diagnosis of knee pain.  相似文献   
7.
8.
We report the case of a 20-year-old man with an ipsilateral mid-third clavicle fracture with grade V acromioclavicular joint (ACJ) dislocation. The combination of these two injuries is rare. A literature search produced various treatment algorithms. In this case, the patient was successfully treated with a Bosworth screw.This work was carried out in the Department of Orthopaedics, William Harvey Hospital, Ashford, Kent, UK  相似文献   
9.
10.
The immediate surgical goals in the treatment of thoraco-lumbar fractures are decompression of compromised neural structures and stabilization of the vertebral column. If more sophisticated instrumentation is available, e.g. A.O.-fixateur interne or instrument set according to Kluger, stable reposition and reformation of compressed vertebral bodies also becomes possible. The long-term goals are to prevent delayed onset of spinal deformity, pain, and further neurological deficit. Early operative stabilization also shortens hospitalization time and allows immediate ambulation, thus lessening pulmonary, vascular, urological, and psychological complications. The Department of Neurosurgery, Sher-I-Kashmir Institute of Medical Sciences, treated 75 cases of thoraco-lumbar fractures. Out of 75 cases 63 were operated upon: 32 cases by spinal fusion alone and 31 by a combined procedure of decompression and posterior spinal fusion with fibular graft. 52 showed evidence of recovery ranging from moderate to excellent in a follow-up of 2-3 years. Thus surgery resulted not only in giving a stable spine to patients but also good improvement of neurodeficits. Our experiences demonstrate that operative treatment of thoraco-lumbar fractures can give satisfactory results even in situations where sophisticated instrumentation is not available.  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