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   24938篇
  免费   2505篇
  国内免费   1406篇
耳鼻咽喉   214篇
儿科学   338篇
妇产科学   170篇
基础医学   2572篇
口腔科学   549篇
临床医学   2819篇
内科学   3579篇
皮肤病学   480篇
神经病学   1430篇
特种医学   1200篇
外国民族医学   5篇
外科学   3600篇
综合类   4284篇
现状与发展   4篇
一般理论   3篇
预防医学   1833篇
眼科学   450篇
药学   2205篇
  33篇
中国医学   1227篇
肿瘤学   1854篇
  2024年   95篇
  2023年   415篇
  2022年   979篇
  2021年   1331篇
  2020年   1116篇
  2019年   860篇
  2018年   879篇
  2017年   841篇
  2016年   844篇
  2015年   1199篇
  2014年   1402篇
  2013年   1592篇
  2012年   2197篇
  2011年   2191篇
  2010年   1587篇
  2009年   1325篇
  2008年   1496篇
  2007年   1460篇
  2006年   1350篇
  2005年   1145篇
  2004年   903篇
  2003年   900篇
  2002年   693篇
  2001年   453篇
  2000年   307篇
  1999年   205篇
  1998年   135篇
  1997年   117篇
  1996年   97篇
  1995年   80篇
  1994年   84篇
  1993年   44篇
  1992年   65篇
  1991年   44篇
  1990年   35篇
  1989年   33篇
  1988年   29篇
  1987年   35篇
  1986年   41篇
  1985年   36篇
  1984年   26篇
  1983年   22篇
  1982年   22篇
  1981年   18篇
  1980年   18篇
  1979年   21篇
  1978年   10篇
  1976年   8篇
  1968年   6篇
  1957年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
病例 患者男性,69岁,主诉:右上腹持续性隐痛伴腹胀1周.既往无肝炎、寄生虫病史.查体:右侧腹部扪及一巨大肿块,向上与肝相续,向下达髂前上棘水平.实验室检查:肝炎病毒系列阴性,肝功能正常, AFP 1.59 U/mL,CA1998.52 U/mL,CEA 0.49 ng/mL. 腹部增强CT提示:肝脏一外生性稍低密度肿...  相似文献   
62.
The primary plasma cell leukemia (pPCL) is a rare but aggressive variant of multiple myeloma (MM). Few studies have focused on the differences in the causes of death between pPCL and MM. This study aimed to compare and evaluate the causes of death of patients with pPCL and MM.The data were collected from the Surveillance Epidemiology, and End Results (SEER) database. The demographic characteristics, survival, and causes of death in pPCL and MM patients were evaluated and compared. The competing risk regression model was performed to predict the cause of death.Between 1975 and 2009, the overall mortality rate was 96.13% and 88.71% for pPCL and MM, and the median survival was 9 and 26 months, respectively. In pPCL, leukemia caused 45.05% of the deaths, followed by myeloma (38.83%). In MM, myeloma was the leading cause of death, accounting for 74.89% of the deaths. Older age at diagnosis was a risk factor for dying of leukemia in pPCL patients (HR = 1.49, 95% CI: 1.16–1.91), while older age at death was associated with reduced risk (HR = 0.67, 95% CI: 0.52–0.86). Although the survival of pPCL patients increased with time periods of diagnosis since 1975 to 2009, the risk of dying of leukemia increased with the periods. For MM, most of the demographic characteristics were found to have independently predicting influence on the cause of death.Patients with pPCL and MM had distinct causes of death. Leukemia was the leading and the most serious cause of death in pPCL patients. The demographic factors could not predict the causes of death in pPCL. More large-scale and multi-center studies are needed to evaluate the effect of novel agents in pPCL patients, especially for patients who have progressed to leukemia.  相似文献   
63.
目的研究人喉癌细胞系Hep-2细胞膜钾离子通道特性及其与RNA编辑酶1(RNA-dependent adenosinedeaminase1,ADAR1)的相关性.方法以Hep-2细胞为研究对象,采用穿孔膜片钳全细胞记录法研究钾离子通道特性,用逆转录聚合酶链反应检测四乙胺(tetraethylammonium,TEA)阻断钾离子通道前后Hep-2细胞ADAR1 mRNA的表达.结果 Hep-2细胞膜的静息膜电位为(-29.8±1.9)mV,在钳制电压-40 mV,阶跃电压在-80~ 80 mV,记录到一种跨膜电流,该跨膜电流具有电压依赖、外向整流特性,该电流在延迟25ms后最大激活,800 ms内不失活,可被阻断剂TEA阻断.Hep-2细胞钾离子通道被TEA阻断前后ADAR1mRNA相对表达量存在显著性差异.结论 Hep-2细胞膜上存在延迟整流钾离子通道,此钾离子通道可能和ADAR1 mRNA的表达密切相关.  相似文献   
64.
目的:探讨罗库溴铵靶控输注(TCI)用于老年患者腹部手术的效果.方法:60例ASAⅡ级、择期全麻腹部手术老年患者(60~80岁),随机分成A、B、C 3组,每组20例.根据预实验结果,将A、B、C 3组诱导插管时罗库溴铵效应室靶浓度 (Ce) 均设置为3 mg/L,术中维持Ce分别为0.6、0.8、1.0 mg/L.观察各组诱导插管起效时间、气管插管条件、术中肌松条件和术后肌松恢复情况.结果:3组均可顺利完成气管插管;术中A组肌松条件满意率低于B组和C组.与B组比较,C组罗库溴铵用量大、术中肌肉阻滞程度较深、术后恢复时间延长(P<0.05).结论:老年患者腹部手术诱导插管时罗库溴铵TCI Ce设置为3 mg/L、术中Ce维持在0.8 mg/L,可以实现诱导插管顺利、术中肌松满意和术毕迅速恢复的目的.  相似文献   
65.
紫檀浸膏对5α-还原酶的抑制作用   总被引:1,自引:1,他引:1  
喻凯 《华西药学杂志》2007,22(5):506-507
目的 从中药中筛选5α-还原酶抑制物质,为开发治疗雄激素失调所致疾病的药物奠定基础.方法 将来自大鼠前列腺的5α-还原酶、丙酸睾酮及中药样品一起孵育,用EIA法测定DHT的生成量来反映酶的活性,筛选抑制酶活性的样品.同时,将所筛选样品用于治疗人工复制的前列腺肥大的大鼠模型,观察疗效.结果 紫檀的甲醇浸膏能抑制5α-还原酶,对人工复制的大鼠前列腺肥大有治疗作用.结论 所建筛选方法高效、可靠,所得紫檀浸膏具有进一步开发的价值.  相似文献   
66.
A new type of modified lignin, lignin-p-Boc, was obtained through reaction with di-tert-butyl dicarbonate (Boc2O) in aqueous media catalyzed by 4-dimethylaminopyridine (DMAP). Boc modification occurred regardless of type of lignin, was tunable, and proceeded well in recovering lignin at high purity from sodium lignosulfonate (a common byproduct from pulping industry; lignin content: 60%). Lignin-p-BOC was demonstrated as a potential reactive filler in green plastic and as a potential crosslinker in design of bioresorbable composite polymeric implants. Furthermore, the effect of the modification on breakdown rate of alkali lignin by microbes was investigated, and results showed that the modification substantially decreases the breakdown rate. The tunable Boc modification process was designed via a system thinking, including availability of raw lignin, economical/green modification, potentiality of drop-in-change to current thermoplastic processing, modification impact on microbial degradability/disposed environment at the end of use life; hence the holistic consideration makes this alternative method for upgrade of technical lignins very practical for future industrial application. Via “in-situ” forming “easily breakable covalent bonds” with existing thermopolymers inside, Lignin-p-BOCs are also promising to play an important role as both excellent binders via “random match” and reductants in transforming linear plastic waste into circular plastics.  相似文献   
67.
This article presents the numerical analysis and experimental investigation for the manufacturing of a foam core sandwich spoiler by vacuum-assisted resin injection (VARI) process. To find an injection scheme that guarantees both a good impregnation of the preform and a filling time compatible with the process window, the finite element model (FEM) was applied to analyze the effect of different injection schemes on the resin flow front patterns. Based on the obtained results, two optimal injection schemes are selected to form the spoiler structure. The experimental results show that the best molding quality can be achieved from the thick-end injection with a thin-end exit scheme. The comparison between simulation and experimental results shows that the overall deviation of the numerical analysis on resin flow time is 15.9%.  相似文献   
68.
The objective of the study was to report clinical outcomes and patterns of failure for these patients with cervical esophageal squamous cell carcinoma (CESCC) treated with intensity-modulated radiotherapy (IMRT). A total of 64 patients with CESCC treated with definitive IMRT from May 2005 to March 2012 in our center were analyzed. Forty-two patients received radiotherapy alone and 22 patients received concurrent chemoradiotherapy. The location and extent of locoregional failures were transferred to the pretreatment planning computed tomography for dosimetry analysis. For all patients, the overall 2-year local failure-free survival, regional failure-free survival, distant failure-free survival, and overall survival rate was 74.5, 88.0, 66.6 and 42.5 %, respectively. Twenty-eight patients had developed treatment failure. Of the 28 patients, 14, 5, and 18 had developed local failure, regional failure, and distant metastasis, respectively. All of the 14 local failures were considered in-field failures. Of the five regional failures, three were considered in-field failures and two were marginal failures. The most frequently observed acute toxicity was mainly Grade 1 or 2. The incidence of acute Grade 3 mucositis (including pharyngitis), skin reaction, and leukopenia was 4.7, 12.5 and 10.9 %, respectively. IMRT provides satisfactory locoregional control for CESCC. Distant metastasis remains the predominate pattern of failure and the predominate pattern of locoregional failures is in-field failure.  相似文献   
69.
目的:比较中国北方地区树木花粉、杂草花粉以及尘螨引起的变应性鼻炎(AR)患者的生活质量水平,伴随哮喘情况,探讨AR患者的生活质量与变应原血清特异性IgE的关系。方法:选取164例AR伴或不伴哮喘的成人患者,完成病史采集及变应原检查,并填写标准化鼻结膜炎生存质量调查问卷(RQLQ)。结果:中国北方地区AR患者中,树木花粉组及杂草花粉组的RQLQ总评分、日常活动评分、鼻部症状及眼部症状评分均显著高于尘螨组,生活质量更差。树木花粉组的哮喘比例明显低于尘螨组,而杂草花粉组的哮喘比例则与尘螨组无明显差异,且显著高于树木花粉组。尘螨及蒿属花粉过敏所致的AR患者的RQLQ评分与其变应原特异性IgE水平之间无明显相关性。结论:AR患者的生活质量评分受到变应原具体类型的影响,中国北方地区花粉过敏者发病时的生活质量比尘螨过敏者更差,但生活质量受损程度可能不受变应原特异性IgE水平的影响。不同花粉过敏所致鼻炎合并哮喘的比例不同,杂草花粉可能比树木花粉更容易诱发哮喘。  相似文献   
70.
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