全文获取类型
收费全文 | 37143篇 |
免费 | 1978篇 |
国内免费 | 427篇 |
专业分类
耳鼻咽喉 | 408篇 |
儿科学 | 735篇 |
妇产科学 | 111篇 |
基础医学 | 2073篇 |
口腔科学 | 1123篇 |
临床医学 | 3727篇 |
内科学 | 3467篇 |
皮肤病学 | 153篇 |
神经病学 | 1431篇 |
特种医学 | 7883篇 |
外国民族医学 | 12篇 |
外科学 | 2880篇 |
综合类 | 7980篇 |
预防医学 | 2166篇 |
眼科学 | 167篇 |
药学 | 2124篇 |
45篇 | |
中国医学 | 833篇 |
肿瘤学 | 2230篇 |
出版年
2024年 | 66篇 |
2023年 | 393篇 |
2022年 | 1033篇 |
2021年 | 1352篇 |
2020年 | 1250篇 |
2019年 | 1061篇 |
2018年 | 1171篇 |
2017年 | 1284篇 |
2016年 | 1265篇 |
2015年 | 1141篇 |
2014年 | 2504篇 |
2013年 | 2120篇 |
2012年 | 2079篇 |
2011年 | 2529篇 |
2010年 | 2144篇 |
2009年 | 2242篇 |
2008年 | 2020篇 |
2007年 | 2039篇 |
2006年 | 1705篇 |
2005年 | 1359篇 |
2004年 | 1078篇 |
2003年 | 1066篇 |
2002年 | 995篇 |
2001年 | 793篇 |
2000年 | 689篇 |
1999年 | 565篇 |
1998年 | 466篇 |
1997年 | 415篇 |
1996年 | 301篇 |
1995年 | 343篇 |
1994年 | 308篇 |
1993年 | 182篇 |
1992年 | 193篇 |
1991年 | 152篇 |
1990年 | 126篇 |
1989年 | 116篇 |
1988年 | 93篇 |
1987年 | 100篇 |
1986年 | 79篇 |
1985年 | 149篇 |
1984年 | 132篇 |
1983年 | 55篇 |
1982年 | 99篇 |
1981年 | 98篇 |
1980年 | 73篇 |
1979年 | 54篇 |
1978年 | 37篇 |
1977年 | 22篇 |
1976年 | 6篇 |
1967年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
我院自 1994年使用CT检查以来 ,需增强检查者的比例越来越高。增强检查确实提供了CT平扫不可替代的诊断信息 ,但是碘对比剂的副作用却令人担忧 ,因此 ,CT室的护理人员应认真做好对患者的筛选、敏试工作 ,严格掌握禁忌证 ,加强对副反应的预防性措施及意外抢救工作 ,合理使用对比剂 ,现将我院应用碘对比剂的方法介绍如下。1 严格掌握禁忌证严重的甲状腺功能亢进、失代偿性心肌功能不全者禁忌。妊娠及急性盆腔炎症时禁行子宫输卵管造影。2 认真筛选高危因素有碘造影剂过敏、严重肝肾功能损害、心脏和循环功能不全、肺气肿、体质极差者 ,重… 相似文献
32.
Peter B. Richman MD Shari Dominguez MD David Kasper MD Frederick Chen MD Jeremy Friese MD Joseph Wood MD JD Joseph Collins MD Jeffrey A. Kline MD 《Academic emergency medicine》2006,13(3):295-301
Objectives: To determine interobserver agreement between radiologists for computed tomography (CT) angiography and venography. CT venography of the lower extremities combined with standard CT angiography of the chest may result in an increased overall diagnosis rate of venous thromboembolism (pulmonary embolism or deep venous thrombosis).
Methods: The study had a retrospective cohort design. The population consisted of emergency department patients who were evaluated for suspected pulmonary embolism. A random sample of 50 patients diagnosed and treated for venous thromboembolism and 50 age- and gender-matched patients whose CT angiograms and venograms were read as negative were enrolled. The original reading (R1) was compared with readings of two study radiologists: R2, a general radiologist, and R3, a radiologist with fellowship training in cross-sectional imaging. All readers were blinded to each other.
Results: Both R2 and R3 found both CT angiogram and venogram components technically adequate in 95% (95% CI = 89% to 98%) and 86% (95% CI = 78% to 92%) of studies, respectively. The agreement was very good for CT angiography (lowest agreement = 92%; lowest κ = 0.83) and was good for CT venography (85%, κ = 0.65). In nine cases, R1 read the CT angiogram as negative but the venogram as positive for DVT, whereas both R2 and R3 read both components as negative in four of these nine, suggesting a false-positive isolated DVT rate of 44% (95% CI = 19% to 73%). In no case did R1 read both scan components as negative when R2 and R3 agreed on presence of pulmonary embolism or DVT.
Conclusions: Diagnosis of pulmonary embolism on CT angiography is more reliable than diagnosis of isolated DVT on CT venography. 相似文献
Methods: The study had a retrospective cohort design. The population consisted of emergency department patients who were evaluated for suspected pulmonary embolism. A random sample of 50 patients diagnosed and treated for venous thromboembolism and 50 age- and gender-matched patients whose CT angiograms and venograms were read as negative were enrolled. The original reading (R1) was compared with readings of two study radiologists: R2, a general radiologist, and R3, a radiologist with fellowship training in cross-sectional imaging. All readers were blinded to each other.
Results: Both R2 and R3 found both CT angiogram and venogram components technically adequate in 95% (95% CI = 89% to 98%) and 86% (95% CI = 78% to 92%) of studies, respectively. The agreement was very good for CT angiography (lowest agreement = 92%; lowest κ = 0.83) and was good for CT venography (85%, κ = 0.65). In nine cases, R1 read the CT angiogram as negative but the venogram as positive for DVT, whereas both R2 and R3 read both components as negative in four of these nine, suggesting a false-positive isolated DVT rate of 44% (95% CI = 19% to 73%). In no case did R1 read both scan components as negative when R2 and R3 agreed on presence of pulmonary embolism or DVT.
Conclusions: Diagnosis of pulmonary embolism on CT angiography is more reliable than diagnosis of isolated DVT on CT venography. 相似文献
33.
目的:探讨CT、X线诊断胸壁病变的价值。材料和方法:回顾性分析53例胸壁病变的CT和X线表现,并评估其诊断价值。结果:53例中,CT确诊52例,X线平片确诊41例。正常7例,炎性和脓肿3例、骨折6例、胸膜病变12例(粘连4例、胸膜增厚3例、胸膜钙化3例、结核瘤2例)、良性肿瘤9例(脂肪瘤3例、神经纤维瘤3例、嗜酸性肉芽肿2例、间皮瘤1例)、恶性肿瘤16例(转移瘤13例、骨髓瘤3例)。结论:CT正确诊断率(98%)明显高于X线(77%),可以明确诊断胸壁病变,能发现X线平片不能发现的征象,具有较高的诊断价值。 相似文献
34.
Mayte Ramirez Francisco Garcí a-Rí o Aleydis Vi as Concepci n Prados Jos M. Pino Jos Villamor 《The Journal of asthma》2005,41(1):109-116
The study objectives were to analyze the changes in exhaled carbon monoxide (COex) induced by histamine provocation challenge in asthmatic patients and to evaluate the relationship between COex and airway sensitivity and reactivity. Levels of COex were measured in 105 nonsmoking mildly asthmatic subjects before and after histamine provocation challenge. Dose-response curves were characterized by their sensitivity (PD20) and reactivity. Dose-response slope (DRS), continuous index of responsiveness (CIR), and bronchial reactivity index (BRI) were determined as reactivity indices. Bronchial challenge was positive for 47 subjects and negative for 58. The COex levels rose significantly after bronchial challenge in the positive response group (4.49 ± 0.4 vs. 5.74 ± 0.57 ppm, p = 0.025) and in the negative response group (2.84 ± 0.25 vs 4.00 ± 0.41 ppm, p = 0.000). An inverse relation between basal COex and PD20 was found (r = - 0.318, p = 0.030). In all subjects, a proportional direct relationship between COex and DRS (r = 0.214, p = 0.015), CIR (r = 0.401, p = 0.000), and BRI (r = 0.208, p = 0.012) was observed. On stepwise multiple linear regression analysis, COex only significantly correlated with CIR (multiple r2 = 0.174, p = 0.000). In conclusion, exhaled CO determination is a noninvasive inflammatory marker of the respiratory tract, which shows an acceptable association with airway hyperresponsiveness. 相似文献
35.
目的 :探讨CT引导下微创清除术治疗急性高血压脑出血的疗效。方法 :对 38例急性高血压脑出血患者微创清除术前后行CT扫描 ,在CT引导下行微创清除术 ,并动态观察其疗效。结果 :38例急性高血压脑出血患者首次血肿清除率达 2 8.0 %~ 4 0 .0 %,其中 1 2例首次清除率为 4 0 .0 %~ 5 6 .0 %。存活 32例 7d后复查头颅CT证实者血肿清除率达 80 %以上。治愈有效率为 84 .2 %,死亡率为 1 5 .8%。结论 :CT引导下的微创清除术能有效地降低急性高血压脑出血的死亡率和致残率。 相似文献
36.
37.
目的:探讨食管癌X线检查与术前CT检查的临床意义.方法:收集50例食管癌患者的X线CT检查进行分析.结果:食道吞钡均能发现食管癌,且已处于中晚期;术前CT检查基本能发现病变,同时还能发现有淋巴或周围软组织侵犯征象.结论:食道吞钡是食管癌首选的检查方法,术前CT检查可为临床治疗进一步提供科学依据. 相似文献
38.
目的:探讨脊柱爆裂型骨折的CT扫描价值. 资料与方法:随机抽取我院1988年至2001年骨科70例脊柱外伤患者的资料.其中男性54例,女性16例.年龄19岁~73岁,平均49岁.全部患者均摄取普通X线片,然后依据X线片提示的骨折部位作CT扫描,采用估算法重建图像,应用骨窗和软组织窗观察,部分病例进行矢状面重组.结果:70例受检者中受损椎体87个,C5损伤1例,T12~L1损伤1例,L1~2损伤1例,其他均为单椎体损伤.按Denis[1]三柱理论,63例病例为爆裂骨折,累及二柱和二柱以上,7例为椎体单纯压缩型骨折,1例伴有严重的脱位.结论:CT在显示椎体骨折尤其是脊柱后结构损伤方面优于X线平片,对判定脊柱稳定程度及损伤有否手术指征帮助最大.当X线摄片之后考虑为爆裂性骨折时,应抓紧作CT扫描检查. 相似文献
39.
目的分析Dandy—Walker综合征的临床及cT与MR!影像特征。方法采用cT与MRI常规扫描,对12例Dandy—Walker综合征的临床表现、CT与MRI征象进行回顾性分析;结果12例Dandy—Walker综合征的CT与MRI表现归纳为①小脑蚓部缺失,小脑半球发育不良、完全分离,分离的小脑半球可以不对称;②第四脑室呈囊状、扇形、三角形显著扩张或后颅窝巨大囊状阴影与第四脑室相通;③窦汇异常抬高,越过人字缝/天幕抬高;④幕上脑室对称性扩张,脑积水。结论对Dandy—Walker综合征的诊断,CT扫描能够显示后颅凹及天幕上下脑的形态与结构,其CT表现具特征性;MRI可多平面扫描,无骨质伪影,显示后颅凹优于CT,在矢状面上可显示小脑、第四脑室、导水管、后颅凹囊肿以及与天幕的关系。CT与MRI扫描对Dandy—Walker综合征能够做出定性诊断,是术前诊断的主要依据,检查无痛苦,有重要的诊断和鉴别诊断价值。 相似文献
40.
目的探讨多层螺旋CT(MSCT)肺密度测定对结缔组织病(CTD)肺间质病变(ILL)早期诊断的临床意义。方法对222例CTD患者及50名正常对照者,应用MSCT附带的Pulmo自动评估软件进行上、中、下肺区的密度测定,并同时进行肺高分辨扫描(}-IR(_1、),分析二者的变化与CTD伴ILL的关系。结果222例cm患者中197例平均肺密度有不同程度的增高,25例平均肺密度正常。157例HRCT有不同程度的肺间质病变,65例HRCT正常。50名正常对照者HRCT均正常,8名平均肺密度有不同程度的增高,42名平均肺密度正常。结论采用MSCT与HRCT对CTD伴ILL的检测结果差异有统计学意义,P=0.000(双侧),因此MSCT平均肺密度测定对早期诊断CTD伴ILL比HRCT更敏感,更有临床意义。 相似文献