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   290717篇
  免费   25845篇
  国内免费   5056篇
耳鼻咽喉   3499篇
儿科学   5886篇
妇产科学   4990篇
基础医学   21667篇
口腔科学   11268篇
临床医学   34277篇
内科学   27208篇
皮肤病学   2944篇
神经病学   14919篇
特种医学   6436篇
外国民族医学   11篇
外科学   23019篇
综合类   40709篇
现状与发展   11篇
一般理论   110篇
预防医学   61268篇
眼科学   2321篇
药学   22940篇
  411篇
中国医学   26833篇
肿瘤学   10891篇
  2024年   1253篇
  2023年   6661篇
  2022年   10995篇
  2021年   14749篇
  2020年   14598篇
  2019年   15830篇
  2018年   13764篇
  2017年   12213篇
  2016年   11108篇
  2015年   10577篇
  2014年   19414篇
  2013年   21474篇
  2012年   17181篇
  2011年   18570篇
  2010年   14630篇
  2009年   13275篇
  2008年   12513篇
  2007年   12626篇
  2006年   10796篇
  2005年   8881篇
  2004年   7430篇
  2003年   6525篇
  2002年   4995篇
  2001年   4355篇
  2000年   3844篇
  1999年   2986篇
  1998年   2429篇
  1997年   2120篇
  1996年   1716篇
  1995年   1520篇
  1994年   1376篇
  1993年   1255篇
  1992年   1121篇
  1991年   1010篇
  1990年   876篇
  1989年   817篇
  1988年   793篇
  1987年   687篇
  1986年   619篇
  1985年   1879篇
  1984年   2121篇
  1983年   1335篇
  1982年   1756篇
  1981年   1223篇
  1980年   1058篇
  1979年   935篇
  1978年   772篇
  1977年   587篇
  1976年   721篇
  1975年   509篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A retrospective clinico-pathological study has been carried out in a series of 405 patients with squamous cell carcinoma of the head and neck who underwent a total of 484 radical neck dissections. The recurrence rate in the neck in 327 patients who had histological positive nodes was 21.1%, Recurrence in the neck after a standard radical neck dissection almost invariably proved fatal. A statistical analysis has been carried out to evaluate the clinical and pathological factors which are of importance in regards to recurrence in the neck. Histological factors such as extra-nodal spread and the number of histological positive nodes have been shown to be of much more prognostic importance than clinical parameters. When corrections are made for interdependencies between variables, histological extra-nodal spread proved to be the most important single prognostic factor (P < 10?7).  相似文献   
992.
本文对25例头颈部肿瘤患者的外周血NK细胞杀伤活性及NK细胞计数进行测定,其中有15例患者手术治疗切除肿瘤,于术后三周复查NK活性及NK计数,并与正常人组对照。实验结果显示:头颈部肿瘤患者NK活性及NK计数均低于正常人,两组比较均有极显著性差异(P<0.01);术后患者的NK活性比术前有明显提高,配对t检验P<0.01,NK计数比术前也有所提高,配对t检验P<0.05,有显著性差异;NK活性的水平与肿瘤的分期有相关性,晚期(T4期)癌症患者NK活性明显低于早期(T1、T2)患者,可以看出NK活性随着肿瘤的发展而降低,肿瘤对宿主有免疫抑制作用;NK活性与NK数量之间无显著的相关性,二者之间的相关系数r=0.344。  相似文献   
993.
爱维治治疗前部缺血性视神经病变的疗效观察   总被引:7,自引:0,他引:7  
目的 观察爱维治治疗前部缺血性视神经病变(AION)的疗效。 方法 临床确诊的AION患者58例60只眼,其中29例30只眼接受爱维治1200 mg/d静脉滴注治疗(治疗组);另外29例30只眼接受1~2种溶栓抗凝剂或血管扩张剂1次/d静脉滴注治疗(对照组)。均以15 d为1个疗程。对照组中20只眼还同时进行眼局部药物注射,包括糖皮质激素、654-2球后或球旁注射,1次/d或1次/2 d,用药3~5次。两组患者用药后每天观察视力、眼底变化,治疗前有视野检查者复查视野。 结果 治疗组视力提高程度明显好于对照组,两组间差异有统计学意义(t=2.74, P<0.01); 用药第3天,两组视力提高程度差异无统计学意义(t=1.34, P>0.05); 第5、10、15天,治疗组视力提高程度明显好于对照组,其差异有统计学意义(t=2.01, P<0.05; t=2.07, P<0.05; t=2.74, P<0.01);治疗组有视野检查的15只眼中,13只眼治疗后视野好转,占87.00%;2只眼无变化,占13.00%。对照组有视野检查的13只眼中,4只眼治疗后视野好转,占31.00%;9只眼无变化,占69.00%。两组视野变化的差异比较有统计学意义(χ2=9.66,P<0.01)。 结论 爱维治治疗AION有效。 (中华眼底病杂志, 2006, 22: 97-99)  相似文献   
994.
目的探讨唇腭裂婴幼儿畸变产物耳声发射(distortion product otoacoustic emission,DPOAE)的特点,并将其与听性脑干反应(auditory brainstem response,ABR)阂值检查的结果加以对照,以探讨DPOAE在这类患儿听力检查中的应用价值。方法DPOAE检查63例(126耳),年龄2个月-42个月,平均11.83个月。其中单纯腭裂组(以下简称腭裂组)23例(46耳),腭裂并发唇裂及牙槽裂组(以下简称唇腭裂组)30例(60耳),单纯唇裂组(以下简称唇裂组)10例(20耳),每耳均检查8个频率,若2-5kHz4个频点有≥3个频点通过即为该耳通过。在上述患儿中,ABR阈值检查腭裂组17例(34耳),唇腭裂组10例(20耳),唇裂组6例(12耳),以能重复引出V波的最小刺激强度为ABR阈值。结果DPOAE检查:腭裂组通过7耳,未通过39耳,通过率为15.22%;唇腭裂组通过6耳,未通过54耳,通过率为10.00%;唇裂组通过18耳,未通过2耳,通过率为90%。统计分析腭裂组与唇腭裂组无显著差异,而腭裂组与唇裂组,唇腭裂组与唇裂组均有显著差异。ABR阈值检查统计分析结果与DPOAE一致。将各组DPOAE通过率与ABR正常率进行比较,腭裂组及唇腭裂组中二者无差异(P〉0.05),虽然唇裂组中二者有差异(P〈0.05),但唇裂组ABR阈值反应的听力下降较轻(均≤50dB nHL)。从总体趋势上说,DPOAE与ABR阈值检查在检测的结果上是一致的。结论唇腭裂患儿DPOAE和ABR检测结果一致,与ABR相比,DPOAE具有快速、简便、易实施等特点,因此DPOAE可以作为唇腭裂婴幼儿听力检查的手段,但仍需进一步结合ABR及其他相关的听力检查,以明确听力损害的程度和类型。  相似文献   
995.
The preservation of cognitive ability by increasing nicotinamide adenine dinucleotide (NAD+) levels through supplementation with NAD+ precursors has been identified as a promising treatment strategy for a number of conditions; principally, age-related cognitive decline (including Alzheimer’s disease and vascular dementia), but also diabetes, stroke, and traumatic brain injury. Candidate factors have included NAD+ itself, its reduced form NADH, nicotinamide (NAM), nicotinamide mononucleotide (NMN), nicotinamide riboside (NR), and niacin (or nicotinic acid). This review summarises the research findings for each source of cognitive impairment for which NAD+ precursor supplementation has been investigated as a therapy. The findings are mostly positive but have been made primarily in animal models, with some reports of null or adverse effects. Given the increasing popularity and availability of these factors as nutritional supplements, further properly controlled clinical research is needed to provide definitive answers regarding this strategy’s likely impact on human cognitive health when used to address different sources of impairment.  相似文献   
996.
997.
Background: Obesity relates to impaired olfactory function. Abnormal olfactory function is also associated with poor diet; however, whether obesity-related markers shape this relationship is unknown. Methods: Cross-sectional analysis (n = 1415, age > 40 years) of NHANES 2013–2014 examined body fat percent (BF%) and waist circumference (WC) as moderators of the relationship between olfactory function and diet. The olfactory function test identified adults with olfactory dysfunction (OD) or normal olfaction (NO). Validated 24 h recall captured nutrient intake and Healthy Eating Index-2010 scores. BF% and WC were measured. We tested adjusted linear regression models, with an interaction term between olfactory function and BF%/WC, for each nutrient or HEI score, and reported coefficients (β), standard errors (SE), and p-values for significant interaction terms. Results: In OD (9.5%; mean age 50.9 years, 95% CI 49.6, 52.2) compared with NO (mean age 49.3 years, 95% CI 48.8, 49.9), higher BF% was associated with higher intake of saturated fat (β (SE): 0.2 (0.1) g; p = 0.06) and percent of total calories from total fat (0.2 (0.1); p = 0.07), saturated (0.1 (0.004); p = 0.02), and monounsaturated fat (0.1 (0.1); p = 0.08); lower percent of total calories from carbohydrates (−0.2 (0.1); p = 0.09) and mg of sodium (−17.8 (09.6); p = 0.08); and a higher (healthier) refined grain score (0.1 (0.1); p = 0.04). Higher WC was associated with higher refined grain scores (0.01 (0.02); p = 0.01) in OD. Conclusion: BF% may shape dietary intake and quality in OD. Longitudinal studies are needed to elucidate the directionality of these relationships and develop strategies to improve dietary intake among OD.  相似文献   
998.
头颈部遗传性肿瘤主要包括家族性头颈部副神经节瘤、多发性内分泌腺瘤病1型、多发性内分泌腺瘤病2型、家族性甲状旁腺功能亢进、家族性甲状腺乳头状癌、神经纤维瘤病I型、神经纤维瘤病II型、家族性鼻咽癌及家族性鳞状细胞癌。本文从头颈部遗传性肿瘤的分类、临床特征、遗传学和治疗等方面做一综述。  相似文献   
999.
目的利用人工智能技术分析近年中国互联网用户对于过敏性鼻炎(allergic rhinitis,AR)的网上检索信息,以帮助耳鼻咽喉科医师更好地了解AR患者的实际需求,从而在临床实践中更加合理地对患者进行管理。  相似文献   
1000.
Fetal stroke is an important cause of cerebral palsy but is difficult to diagnose unless imaging is undertaken in pregnancies at risk because of known maternal or fetal disorders. Fetal ultrasound or magnetic resonance imaging may show haemorrhage or ischaemic lesions including multicystic encephalomalacia and focal porencephaly. Serial imaging has shown the development of malformations including schizencephaly and polymicrogyra after ischaemic and haemorrhagic stroke. Recognised causes of haemorrhagic fetal stroke include alloimmune and autoimmune thrombocytopaenia, maternal and fetal clotting disorders and trauma but these are relatively rare. It is likely that a significant proportion of periventricular and intraventricular haemorrhages are of venous origin. Recent evidence highlights the importance of arterial endothelial dysfunction, rather than thrombocytopaenia, in the intraparenchymal haemorrhage of alloimmune thrombocytopaenia. In the context of placental anastomoses, monochorionic diamniotic twins are at risk of twin twin transfusion syndrome (TTTS), or partial forms including Twin Oligohydramnios Polyhydramnios Sequence (TOPS), differences in estimated weight (selective Intrauterine growth Retardation; sIUGR), or in fetal haemoglobin (Twin Anaemia Polycythaemia Sequence; TAPS). There is a very wide range of ischaemic and haemorrhagic injury in a focal as well as a global distribution. Acute twin twin transfusion may account for intraventricular haemorrhage in recipients and periventricular leukomalacia in donors but there are additional risk factors for focal embolism and cerebrovascular disease. The recipient has circulatory overload, with effects on systemic and pulmonary circulations which probably lead to systemic and pulmonary hypertension and even right ventricular outflow tract obstruction as well as the polycythaemia which is a risk factor for thrombosis and vasculopathy. The donor is hypovolaemic and has a reticulocytosis in response to the anaemia while maternal hypertension and diabetes may influence stroke risk. Understanding of the mechanisms, including the role of vasculopathy, in well studied conditions such as alloimmune thrombocytopaenia and monochorionic diamniotic twinning may lead to reduction of the burden of antenatally sustained cerebral palsy.  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