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   25115篇
  免费   3048篇
  国内免费   608篇
耳鼻咽喉   88篇
儿科学   500篇
妇产科学   1244篇
基础医学   1393篇
口腔科学   183篇
临床医学   7885篇
内科学   3657篇
皮肤病学   301篇
神经病学   902篇
特种医学   1558篇
外国民族医学   6篇
外科学   2915篇
综合类   4002篇
现状与发展   3篇
预防医学   1126篇
眼科学   449篇
药学   1080篇
  51篇
中国医学   236篇
肿瘤学   1192篇
  2024年   112篇
  2023年   551篇
  2022年   1005篇
  2021年   1214篇
  2020年   1504篇
  2019年   1275篇
  2018年   1236篇
  2017年   1251篇
  2016年   1221篇
  2015年   1228篇
  2014年   2078篇
  2013年   1904篇
  2012年   1410篇
  2011年   1503篇
  2010年   1169篇
  2009年   1079篇
  2008年   1136篇
  2007年   1158篇
  2006年   948篇
  2005年   773篇
  2004年   646篇
  2003年   622篇
  2002年   494篇
  2001年   417篇
  2000年   331篇
  1999年   326篇
  1998年   269篇
  1997年   272篇
  1996年   233篇
  1995年   190篇
  1994年   174篇
  1993年   148篇
  1992年   123篇
  1991年   113篇
  1990年   89篇
  1989年   68篇
  1988年   64篇
  1987年   52篇
  1986年   60篇
  1985年   93篇
  1984年   65篇
  1983年   22篇
  1982年   48篇
  1981年   29篇
  1980年   25篇
  1979年   21篇
  1978年   9篇
  1977年   5篇
  1976年   3篇
  1973年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
杨凡  程文 《现代肿瘤医学》2022,(8):1524-1527
超声微血管成像技术是在多普勒血流成像基础上发展起来的新型多普勒成像模式,对微细血管结构及深部血管的显示存在极大的优势。研究显示,超声微血管成像技术在乳腺、甲状腺、肝脏、颈动脉斑块、肌骨、肾脏以及淋巴结疾病中有较好的应用,在疾病活动分级及监测治疗反应中也显示出特殊的应用价值。本文将从以下三个方面对超声微血管成像技术展开综述:超声微血管成像技术的原理、超声微血管成像技术的临床应用以及超声微血管成像技术的现状和展望。  相似文献   
72.
目的探讨超声引导下置管引流在肝移植拔除T管后胆漏中的价值,并与其他处理方法作比较。方法2001年8月至2005年3月肝移植行胆管端端吻合或胆肠吻合放置T管患者76例,拔除T管后发生胆漏9例,其中8例患者行超声引导下置管引流,男性7例,女性1例,年龄22-59岁,平均46.7岁。穿刺置管引流术方法为确定穿刺点,在超声引导下采用Seldinger法徒手操作,18G穿刺针穿入积液内,观察到针尖进入积液区后拔出针芯,见液体流出或抽出液体后放入导丝,退出穿刺针放置带内套针的7F直通管,导管进入积液内退出内套针和导丝,局部固定包敷引流管。结果8例患者拔除T管后分别出现剧烈腹痛、发烧、大汗淋漓等症状,超声检查发现均有盆腔积液,积液最大深度范围为3~7cm。8例超声引导下置管引流均一次成功,引流出淡黄色或金黄色胆汁,1d内症状均迅速改善或消失。5~10d后见管内无引流液后拔管,无并发症发生。结论超声引导下置管引流对肝移植拔除T管后胆漏的治疗是安全、有效的,具有重要价值。  相似文献   
73.
PurposeTerlipressin improves renal function in patients with septic shock. However, the mechanism remains unclear. Here, we aimed to evaluate the effects of terlipressin on renal perfusion in patients with septic shock.Materials and MethodsThis pilot study enrolled patients with septic shock in the intensive care unit of the tertiary hospital from September 2019 to May 2020. We randomly assigned patients to terlipressin and usual care groups using a 1:1 ratio. Terlipressin was intravenously pumped at a rate of 1.3 μg/kg/hour for 24 h. We monitored renal perfusion using renal contrast-enhanced ultrasound (CEUS). The primary outcome was peak sonographic signal intensity (a renal perfusion parameter monitored by CEUS) at 24 h after enrollment.Results22 patients were enrolled in this study with 10 in the terlipressin group and 12 in the usual care group. The baseline characteristics of patients between the two groups were comparable. The peak sonographic signal intensity at 24 h after enrollment in the terlipressin group (60.5 ± 8.6 dB) was significantly higher than that in the usual care group (52.4 ± 7.0 dB; mean difference, 7.1 dB; 95% CI, 0.4–13.9; adjusted p = .04). Patients in the terlipressin group had a lower time to peak, heart rates, norepinephrine dose, and a higher stroke volume at 24 h after enrollment. No significant difference in the urine output within 24 h and incidence of acute kidney injury within 28 days was found between the two groups.ConclusionsTerlipressin improves renal perfusion, increases stroke volume, and decreases norepinephrine dose and heart rates in patients with septic shock.  相似文献   
74.
This current case report presents the detailed clinicopathological analysis of three patients with papillary thyroid carcinoma, each of which presented with the ‘snowstorm appearance’ on ultrasonography. Ultrasonography of this tumour typically shows a diffusely enlarged thyroid with hypoechoic and heterogeneous internal echoes, and diffusely scattered microcalcifications, which form the ‘snowstorm appearance’. Microscopically, case 1 had a large number of psammoma bodies, infiltration of lymphocytes, formation of lymphatic follicles and extensive squamous metaplasia, leading to the diagnosis of a diffuse sclerosing variant of papillary thyroid carcinoma (DSVPTC). Case 2 was diagnosed with follicular papillary thyroid carcinoma. Their tumour had numerous calcifications in the stroma and follicles. Case 3 was diagnosed with a multifocal papillary thyroid carcinoma in the background of Hashimoto''s thyroiditis. Their tumour showed calcification in the stroma and follicles, together with cervical lymph node metastasis. DSVPTC is a rare variant of thyroid papillary carcinoma. It has the ‘snowstorm appearance’ on ultrasound, but this can also be found in follicular papillary carcinoma and multifocal thyroid papillary carcinoma. Papillary thyroid carcinoma with the ‘snowstorm appearance’ has a large number of peripheral lymph nodes metastases, thus requiring radical surgery and postoperative adjuvant therapy.  相似文献   
75.
目的:观察经阴道或直肠彩色多普勒超声在多囊卵巢综合征中的诊断价值。方法:经阴道或经直肠行彩色多普勒超声检查,显示双侧卵巢内部结构,记录最多切面卵泡数,测量最大切面卵巢径线,计算卵巢体积,选用面积测量软件包测量卵巢面积(TA)、髓质面积(SA),然后计算SA/TA,并记录。启动彩色多普勒和频谱多普勒测量卵巢间质动脉搏动指数(PI)、阻力指数(RI)值。所有数据均测量3次并取平均值。结果:多囊卵巢综合征组患者卵巢体积增大(>10mL),双侧卵巢呈多囊样改变,多见10个以上小囊,小囊直径约4~6mm。卵巢间质回声增强,面积增大,间质面积比例较对照组显著增大,P<0.05,卵巢间质血流较丰富,卵巢间质动脉血流RI、PI与对照组比较,差异有统计学意义。结论:经阴道或经直肠彩色多普勒超声,可更直观准确显示卵巢特征。最多切面卵巢小卵泡数目、间质面积比、卵巢间质动脉阻力指数相结合对诊断多囊卵巢综合征(PCOS)有很重要的临床价值。  相似文献   
76.
A new drug-targeting system for CD13+ tumors has been developed, based on ultrasound-sensitive nanobubbles (NBs) and cell-permeable peptides (CPPs). Here, the CPP-doxorubicin conjugate (CPP-DOX) was entrapped in the asparagine–glycine–arginine (NGR) peptide modified NB (CPP-DOX/NGR-NB) and the penetration of CPP-DOX was temporally masked; local ultrasound stimulation could trigger the CPP-DOX release from NB and activate its penetration. The CPP-DOX/NGR-NBs had particle sizes of about 200?nm and drug entrapment efficiency larger than 90%. In vitro release results showed that over 85% of the encapsulated DOX or CPP-DOX would release from NBs in the presence of ultrasound, while less than 1.5% of that (30?min) without ultrasound. Cell experiments showed the higher cellular CPP-DOX uptake of CPP-DOX/NGR-NB among the various NB formulations in Human fibrosarcoma cells (HT-1080, CD13+). The CPP-DOX/NGR-NB with ultrasound treatment exhibited an increased cytotoxic activity than the one without ultrasound. In nude mice xenograft of HT-1080 cells, CPP-DOX/NGR-NB with ultrasound showed a higher tumor inhibition effect (3.1% of T/C%, day 24), longer median survival time (50 days) and excellent body safety compared with the normal DOX injection group. These results indicate that the constructed vesicle would be a promising drug delivery system for specific cancer treatment.  相似文献   
77.
Naturally occurring sono- and photoactive minerals, which are abundant on Earth, represent an attractive alternative to the synthesized sonophotocatalysts as cost-effective materials for water and wastewater treatment. This study focuses on characterizing and evaluating the sonophotocatalytic activity of natural sphalerite (NatS) from Dovatka deposit (Siberia) under high-frequency ultrasonic (US, 1.7 MHz) and ultraviolet light-emitting diodes (UVA LED, 365 nm) irradiation towards degradation of 4-chlorophenol as a model organic pollutant. Since raw natural sphalerite did not exhibit a measurable photocatalytic activity, it was calcined at 500, 900 and 1200 °C. The natural sphalerite after calcination at 900 °C (NatS*) was found to be the most effective for sonophotocatalytic degradation of 4-chlorophenol, attaining the highest efficiency (55%, 1 h exposure) in the following row: UV < US ≈ UV/US ≈ US/NatS* < UV/NatS* < UV/US/NatS*. Addition of 1 mM H2O2 increased the removal to 74% by UV/US/NatS*/H2O2 process. An additive effect between UV/NatS* and US/NatS* processes was observed in the sonophotocatalytic system as well as in the H2O2-assisted system. We assume that the sonophotocatalytic hybrid process, which is based on the simultaneous use of high-frequency ultrasound, UVA light, calcined natural sphalerite and H2O2, could provide a basis of an environmentally safe and cost-effective method of elimination of organic pollutants from aqueous media.  相似文献   
78.
林晓纯  程文 《现代肿瘤医学》2022,(24):4573-4576
人工智能是利用计算机模拟人类学习、思考及作出判断的技术和方法,在医学影像领域应用中为临床流程带来便利,也为疾病诊断、治疗和预后提供更多的信息。而超声技术与人工智能的结合为乳腺诊断带来革新,本文就人工智能在乳腺超声中的流程及方法、应用和发展作一综述。  相似文献   
79.
80.
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