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   301017篇
  免费   24422篇
  国内免费   8645篇
耳鼻咽喉   3116篇
儿科学   10374篇
妇产科学   6737篇
基础医学   38180篇
口腔科学   5220篇
临床医学   30806篇
内科学   44065篇
皮肤病学   4228篇
神经病学   18156篇
特种医学   6794篇
外国民族医学   41篇
外科学   33888篇
综合类   44185篇
现状与发展   29篇
一般理论   25篇
预防医学   18130篇
眼科学   6841篇
药学   23437篇
  156篇
中国医学   18948篇
肿瘤学   20728篇
  2024年   493篇
  2023年   4388篇
  2022年   7003篇
  2021年   12607篇
  2020年   11468篇
  2019年   10359篇
  2018年   10290篇
  2017年   10269篇
  2016年   10467篇
  2015年   10255篇
  2014年   18004篇
  2013年   19233篇
  2012年   15579篇
  2011年   18044篇
  2010年   14863篇
  2009年   14574篇
  2008年   14569篇
  2007年   15683篇
  2006年   14299篇
  2005年   13217篇
  2004年   11549篇
  2003年   10231篇
  2002年   7470篇
  2001年   7113篇
  2000年   5881篇
  1999年   5428篇
  1998年   4152篇
  1997年   3707篇
  1996年   3686篇
  1995年   3507篇
  1994年   3116篇
  1993年   2804篇
  1992年   2455篇
  1991年   2071篇
  1990年   1766篇
  1989年   1617篇
  1988年   1556篇
  1987年   1267篇
  1986年   1010篇
  1985年   1240篇
  1984年   1166篇
  1983年   720篇
  1982年   921篇
  1981年   792篇
  1980年   668篇
  1979年   563篇
  1978年   423篇
  1977年   349篇
  1976年   344篇
  1975年   207篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
目的探讨经鼻间歇正压通气(NIPPV)在防治早产儿呼吸窘迫综合征(RDS)中的应用价值。方法选择2017年6月至2018年12月梧州市人民医院RDS早产儿90例,其中男性48例,女性42例;胎龄(29.03±0.58)周;出生体质量(996.91±98.52)g;病程(3.48±0.56)h;临床分级Ⅰ级58例,Ⅱ级32例;Apgar评分(6.85±1.06)分。依据随机数字表分为NIPPV组和持续气道正压通气(NCPAP)组,每组45例。NIPPV组给予NIPPV治疗,NCPAP组给予NCPAP治疗,若两组治疗后不能维持患儿生命体征则使用肺表面活性物质(PS)或行有创机械通气。结果NIPPV组和NCPAP组治疗12、24 h后和治疗结束时动脉血氧分压(PaO2)、氧合指数(OI)明显高于治疗前。NIPPV组治疗12、24 h后PaO2、OI明显高于NCPAP组,差异有统计学意义(P<0.05)。NIPPV组和NCPAP组治疗结束时PaO2、OI比较,差异无统计学意义(P>0.05);NIPPV组PS使用率(22.22%vs 44.44%)、有创通气率(17.78%vs 40.00%)、氧疗时间[(71.42±7.62)h vs(85.62±9.24)h]、有创通气时间[(46.78±5.32)h vs(55.27±6.14)h]、住院时间[(30.42±3.65)d vs(35.62±3.89)d]、并发症率(31.11%vs 53.33%)明显低于NCPAP组,差异有统计学意义(P<0.05)。结论NIPPV可有效改善RDS早产儿通气功能,有利于减少PS使用、有创通气及并发症,值得临床推广。  相似文献   
82.
83.
Interstitial cystitis/bladder pain syndrome (IC/BPS) and vulvodynia are chronic pain syndromes that appear to be intertwined from the perspectives of embryology, pathology and epidemiology. These associations may account for similar responses to various therapies.  相似文献   
84.
85.
BACKGROUNDGuillain-Barré syndrome (GBS) is a rare disorder that typically presents with ascending weakness, pain, paraesthesias, and numbness, which mimic the findings in lumbar spinal stenosis. Here, we report a case of severe lumbar spinal stenosis combined with GBS.CASE SUMMARYA 70-year-old man with a history of lumbar spinal stenosis presented to our emergency department with severe lower back pain and lower extremity numbness. Magnetic resonance imaging confirmed the diagnosis of severe lumbar spinal stenosis. However, his symptoms did not improve postoperatively and he developed dysphagia and upper extremity numbness. An electromyogram was performed. Based on his symptoms, physical examination, and electromyogram, he was diagnosed with GBS. After 5 d of intravenous immunoglobulin (0.4 g/kg/d for 5 d) therapy, he gained 4/5 of strength in his upper and lower extremities and denied paraesthesias. He had regained 5/5 of strength in his extremities when he was discharged and had no symptoms during follow-up.CONCLUSIONGBS should be considered in the differential diagnosis of spinal disorder, even though magnetic resonance imaging shows severe lumbar spinal stenosis. This case highlights the importance of a careful diagnosis when a patient has a history of a disease and comes to the hospital with the same or similar symptoms.  相似文献   
86.
87.
目的评估血肌酐和尿常规的常规检测基础上联合血清胱抑素C和尿微量白蛋白检测在人类免疫缺陷病毒(HIV)感染者肾功能损伤检测中的应用价值。 方法以2019年2~5月于首都医科大学附属北京地坛医院感染一科住院的169例HIV感染者为研究对象,完善其尿常规、尿微量白蛋白、血肌酐、血清胱抑素C检测;分析尿蛋白及尿微量白蛋白的阳性检出率及其差异,血肌酐升高及血清胱抑素C升高的比例及其差异。计算应用替诺福韦酯(TDF)及合并丙型肝炎、高血压、糖尿病、肿瘤的肾功能损伤的相对危险度。 结果169例HIV感染者中尿常规示尿蛋白阳性者5例(3.0%),尿微量白蛋白升高者17例(10.1%),两者阳性检出率差异具有统计学意义(χ2 = 5.9、P = 0.007)。血肌酐升高者10例(5.9%),血清胱抑素C升高者20例(11.8%),两者阳性检出率差异具有统计学意义(χ2 = 3.0、P = 0.042)。在尿常规和血肌酐检测的基础上联合检测尿微量白蛋白和血清胱抑素C的总体阳性检出率为49例(30.0%)。CD4+ T淋巴细胞计数< 200个/μl与≥ 200个/μl组患者血清胱抑素C水平分别为0.94(0.83,1.05)mg/L、0.85(0.77,0.95)mg/L,差异具有统计学意义(Z =-3.02、P = 0.003)。应用TDF及合并丙型肝炎、高血压、糖尿病、肿瘤的肾功能损伤的相对危险度分别为1.1、1.5、1.9、2.2和1.4。 结论HIV感染者中,单纯以尿常规为依据评估有无蛋白尿,以血肌酐水平为依据评估肾小球滤过功能会低估肾功能损伤的患病率。在常规检测血肌酐和尿常规的基础上联合检测血清胱抑素C和尿微量白蛋白在提高HIV感染者肾功能损伤检出率方面具有重要的应用价值。低CD4+ T淋巴细胞计数、应用TDF及合并丙型肝炎、高血压、糖尿病、肿瘤均为肾功能损伤的危险因素。  相似文献   
88.
89.
INTRODUCTIONPsoriasis is a chronic inflammatory condition that affects the skin and joints, and is associated with cardiovascular risk factors, including metabolic syndrome (MetS). We aimed to assess the prevalence of MetS in patients with psoriasis and determine whether there was a correlation between psoriasis severity and MetS in a Singapore population.METHODSThis was a cross-sectional study of patients with psoriasis, aged 18–69 years, who attended a tertiary dermatology referral centre in Singapore from October 2007 to February 2009. Fasting glucose, lipids, blood pressure, Psoriasis Area and Severity Index, and body mass index were measured. MetS was diagnosed in the presence of three or more criteria of the modified National Cholesterol Education Program Adult Treatment Panel III.RESULTSAmong 338 patients with psoriasis, there were 238 (70.4%) men and 100 (29.6%) women, who were Chinese (n = 228; 67.5%), Malay (n = 52; 15.4%) and Indian (n = 58; 17.2%). The prevalence of MetS was 45.1%. MetS was 44% more prevalent in patients older than 50 years (p = 0.02). Malay patients with psoriasis were significantly more likely to have hypertriglyceridaemia, elevated fasting plasma glucose and abdominal obesity. There was no significant correlation between psoriasis severity and risk of MetS.CONCLUSIONThe prevalence of MetS in patients with psoriasis in Singapore was 45.1%, or nearly threefold higher than the Singapore general population. Patients with psoriasis should be screened yearly for MetS and any modifiable cardiovascular risk factors should be actively controlled.  相似文献   
90.
PurposeTo compare morphological imaging features and CT texture histogram parameters between grade 3 pancreatic neuroendocrine tumors (G3-NET) and neuroendocrine carcinomas (NEC).Materials and methodsPatients with pathologically proven G3-NET and NEC, according to the 2017 World Health Organization classification who had CT and MRI examinations between 2006-2017 were retrospectively included. CT and MRI examinations were reviewed by two radiologists in consensus and analyzed with respect to tumor size, enhancement patterns, hemorrhagic content, liver metastases and lymphadenopathies. Texture histogram analysis of tumors was performed on arterial and portal phase CT images. images. Morphological imaging features and CT texture histogram parameters of G3-NETs and NECs were compared.ResultsThirty-seven patients (21 men, 16 women; mean age, 56 ± 13 [SD] years [range: 28-82 years]) with 37 tumors (mean diameter, 60 ± 46 [SD] mm) were included (CT available for all, MRI for 16/37, 43%). Twenty-three patients (23/37; 62%) had NEC and 14 patients (14/37; 38%) had G3-NET. NECs were larger than G3-NETs (mean, 70 ± 51 [SD] mm [range: 18 - 196 mm] vs. 42 ± 24 [SD] mm [range: 8 - 94 mm], respectively; P = 0.039), with more tumor necrosis (75% vs. 33%, respectively; P = 0.030) and lower attenuation on precontrast (30 ± 4 [SD] HU [range: 25-39 HU] vs. 37 ± 6 [SD] [range: 25-45 HU], respectively; P = 0.002) and on portal venous phase CT images (75 ± 18 [SD] HU [range: 43 - 108 HU] vs. 92 ± 19 [SD] HU [range: 46 - 117 HU], respectively; P = 0.014). Hemorrhagic content on MRI was only observed in NEC (P = 0.007). The mean ADC value was lower in NEC ([1.1 ± 0.1 (SD)] × 10−3 mm2/s [range: (0.91 - 1.3) × 10−3 mm2/s] vs. [1.4 ± 0.2 (SD)] × 10−3 mm2/s [range: (1.1 - 1.6) × 10−3 mm2/s]; P = 0.005). CT histogram analysis showed that NEC were more heterogeneous on portal venous phase images (Entropy-0: 4.7 ± 0.2 [SD] [range: 4.2-5.1] vs. 4.5 ± 0.4 [SD] [range: 3.7-4.9]; P = 0.023).ConclusionPancreatic NECs are larger, more frequently hypoattenuating and more heterogeneous with hemorrhagic content than G3-NET on CT and MRI.  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