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   56080篇
  免费   5010篇
  国内免费   3164篇
耳鼻咽喉   855篇
儿科学   686篇
妇产科学   616篇
基础医学   7511篇
口腔科学   1077篇
临床医学   6699篇
内科学   9286篇
皮肤病学   813篇
神经病学   3318篇
特种医学   2736篇
外国民族医学   21篇
外科学   6123篇
综合类   6459篇
现状与发展   13篇
一般理论   5篇
预防医学   3333篇
眼科学   1306篇
药学   5684篇
  39篇
中国医学   2509篇
肿瘤学   5165篇
  2024年   173篇
  2023年   884篇
  2022年   2165篇
  2021年   3063篇
  2020年   2211篇
  2019年   2021篇
  2018年   2058篇
  2017年   1854篇
  2016年   1851篇
  2015年   2684篇
  2014年   3133篇
  2013年   3048篇
  2012年   4381篇
  2011年   4624篇
  2010年   2877篇
  2009年   2289篇
  2008年   3026篇
  2007年   2955篇
  2006年   2772篇
  2005年   2589篇
  2004年   1906篇
  2003年   1734篇
  2002年   1437篇
  2001年   1145篇
  2000年   1128篇
  1999年   1145篇
  1998年   624篇
  1997年   603篇
  1996年   473篇
  1995年   426篇
  1994年   382篇
  1993年   219篇
  1992年   372篇
  1991年   285篇
  1990年   276篇
  1989年   246篇
  1988年   221篇
  1987年   193篇
  1986年   161篇
  1985年   121篇
  1984年   81篇
  1983年   67篇
  1982年   26篇
  1981年   35篇
  1980年   22篇
  1979年   37篇
  1978年   21篇
  1977年   22篇
  1976年   32篇
  1974年   25篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Humans and animals suffer a health threat to soybean allergy. The impaired mechanism of the intestinal barrier by food/feed allergen glycinin has not been clear. The effects of epithelial metabolic activity, permeability, integrity, and the tight junction (TJ) expression induced by glycinin were conducted using porcine intestinal epithelial cells (IPEC-J2) model in this study. The results showed the decreased metabolic activity (R2 = 0.964, p < 0.001) and the increased alkaline phosphatase activity (R2 = 0.528, p = 0.002) linearly correlated with glycinin levels (0–4 mg/mL). The trans-epithelial electrical resistance values declined stimulated by 4 mg/mL glycinin treatment in a time-dependent manner (0, 6, 12, or 24 h, p = 0.018), and also descended after 12 or 24 h glycinin treatment in dose-dependence (0, 0.5, 1, 2, or 4 mg/mL, p < 0.001). The glycinin-induced TJ expression of claudin-3, occludin, and ZO-1 were reduced (p < 0.05).  相似文献   
992.
目的:探讨活血降脂方对小鼠脂肪肝的防治作用及机制。方法:高脂饲料喂养小鼠,分别用不同剂量的活血降脂方(由人参、三七、天麻组成,命名为GST)给小鼠灌胃2周,检测血脂、肝组织甘油三酯(TG)含量,并观察肝指数和肝脏病理变化,筛选出药物的最佳用药剂量。此外,小鼠分为正常对照(NC)组,喂基础饲料;模型组喂高脂饲料。12周后将模型小鼠随机分为高脂(HF)组,正常饮食(ND)组和GST组。除HF组饲高脂饲料外,其余各组饲基础饲料;GST组给予GST灌胃2周,其余各组以同等容积蒸馏水灌胃。检测血清总胆固醇(TC)、TG、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)及肝组织TC、TG含量,观察肝指数、肝组织超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量,肝组织病理变化及过氧化物酶体增殖物激活受体α(PPARα)、细胞色素P450 2E1(CYP2E1)的mRNA表达。结果:GST可显著降低血脂、肝脂和MDA水平,增加SOD活性,明显降低肝指数并改善肝组织脂肪变性,增加肝组织PPARαmRNA表达、抑制CYP2E1 mRNA的表达。结论:GST具有有效防治脂肪肝的作用,其机制可能与上调肝组织PPARαmRNA的表达、降低血清和肝组织TG含量、下调CYP2E1 mRNA的表达以及抗脂质过氧化反应有关。  相似文献   
993.
目的:观察大鼠脑缺血再灌注损伤后皮质微血管的变化,探讨丁苯酞对其作用。方法:线栓法制备大鼠脑缺血再灌注模型;单宁酸-氯化铁媒染法显示大脑皮质微血管,Mivnt图像分析系统定量分析微血管密度(MVD)和微血管面积密度(MVA);十湿重法检测脑含水量,透射电镜观察血脑屏障超微结构。结果:与假手术组相比,缺血再灌注组大鼠皮质微血管绝大部分闭合或僵直,MVD和MVA显著下降,脑含水量明显升高,电镜观察微血管腔狭窄,内皮细胞核固缩。丁苯酞组微血管形态好转,MVD和MVA升高,脑水肿和血脑屏障损伤程度均减轻。结论:丁苯酞可改善大鼠脑皮质微血管形态,减轻脑水肿和血脑屏障损伤,对脑缺血再灌注损伤有一定的预防性保护作用。  相似文献   
994.
前列腺导管内癌和高级别上皮内瘤变( PIN )在治疗方案上有着显著的区别,但二者的针吸活检组织很难区分。在前列腺根治标本中,作者发现运用PTEN和ERG的免疫组化染色可以解决这一难题。作者在实验中进一步验证在针吸标本中这些标志物是否有用。单独或组合的免疫标记法运用于形态学明确的导管内癌、PIN、交界性导管内增生的活检,后者缺乏类似于导管内癌的形态学准则而比PIN更令人担忧。导管内癌具有侵袭性,有着最高的PTEN丢失率76%(38/50),同时有58%(29/50)表达ERG。导管内癌切除标本显示61%(20/33) PTEN丢失和30%(10/33)的 ERG表达。导管内交界性病变中有52%(11/21)PTEN丢失和27%(4/15)ERG表达。在伴有PTEN丢失的非典型病例中,64%(7/11)在随后的针吸活检标本中检出癌细胞,相比之下, PTEN完好的病例中只检出50%(5/10)。然而,PIN组织中未显示PTEN的丢失以及ERG的表达(0/19)。在针吸活检标本中,导管内癌的 PTEN 丢失很常见,而高级别 PIN 中PTEN丢失很罕见。那些有着PTEN表达丢失的导管内交界性病变中,当再次活检时,癌的可能性很大。如果被大样本的前瞻性研究证实,这个结果将提示PTEN和ERG的免疫染色是一种区分导管内癌和PIN的有效方法。  相似文献   
995.
When access to a major duodenal papilla or endoscopic retrograde cholangiopancreatography has failed, percutaneous transhepatic cholangioscopic lithotripsy (PTCS-L) may be useful for removing common bile duct (CBD) stones. However, the feasibility and usefulness of percutaneous transhepatic papillary large-balloon dilation (PPLBD) during PTCS-L for the removal of large CBD stones has not been established. We aimed to determine the safety and efficacy of PPLBD for the treatment of large CBD stones. Eleven patients with large CBD stones in whom the access to the major papilla or bile duct had failed were enrolled prospectively. Papillary dilation was performed using a large (12-20 mm) dilation balloon catheter via the percutaneous transhepatic route. Post-procedure adverse events and efficacy of the stone retrieval were measured. The initial success rate of PPLBD was 100%. No patient required a basket to remove a stone after PPLBD. Electrohydraulic lithotripsy was required in 2 (18.2%) patients. The median time to complete stone removal after PPLBD was 17.8 min and no adverse events occurred after PPLBD. Asymptomatic hyperamylasemia was not encountered in any patients. This study indicates that PPLBD is safe and effective for removal of large CBD stones.

Graphical Abstract

相似文献   
996.
The purpose of this report was to provide information for patients receiving inpatient rehabilitation after stroke and to identify the possible factors influencing functional outcome after inpatient rehabilitation. Stroke patients (n = 5,212) who were discharged from the Departments of Rehabilitation Medicine (RM) of university hospitals and rehabilitation hospitals from 2007 through 2011 were participants. Prevalence, age, transfer time after onset, length of stay (LOS), functional status at admission and discharge were analyzed. In all stroke subjects, cerebral infarctions (67%) were more common than hemorrhages. Cerebral infarctions in the middle cerebral artery territory were most common, while the basal ganglia and cerebral cortex were the most common areas for hemorrhagic stroke. The LOS decreased from 45 to 28 days. Transfer time after onset decreased from 44 to 30 days. Shorter transfer time after onset was correlated with better discharge functional status and shorter LOS. Initial functional status was correlated with discharge functional status. In ischemic stroke subtypes, cerebellar and brainstem strokes predicted better outcomes, while strokes with more than one territory predicted poorer outcomes with more disabilities. In hemorrhagic stroke subtypes, initial and discharge functional status was the lowest for cortical hemorrhages and highest for brainstem hemorrhages. This report shows that LOS and transfer time after onset has been decreased over time and initial functional status and shorter transfer after onset are predictors of better functional outcome at discharge.  相似文献   
997.
Cardiac arrest (CA) in children is associated with high mortality rates. In Korea, cohort studies regarding the outcomes of pediatric CAs are lacking, especially in emergency departments (EDs) or in-hospital settings. This study was conducted to examine the trends in epidemiology and survival outcomes in children with resuscitation-attempted CAs using data from a cross-sectional, national, ED-based clinical registry. We extracted cases in which cardiopulmonary resuscitation and/or manual defibrillation were performed according to treatment codes using the National Emergency Department Information System (NEDIS) from 2008 to 2012. The total number of ED visits registered in the NEDIS during the 5-yr evaluation period was 20,424,530; among these, there were 2,970 resuscitation-attempted CAs in children. The annual rates of pediatric CAs per 1,000 ED visits showed an upward trend from 2.81 in 2009 to 3.62 in 2012 (P for trend = 0.045). The median number of estimated pediatric CAs at each ED was 7.8 (25th to 75th percentile, 4 to 13) per year. The overall rates for admission survival and discharge survival were 35.2% and 12.8%, respectively. The survival outcome of adults increased substantially over the past 5 yr (11.8% in 2008, 11.7% in 2010, and 13.6% in 2012; P for trend = 0.001); however, the results for children did not improve (13.6% in 2008, 11.4% in 2010, and 13.7% in 2012; P for trend = 0.870). Conclusively, we found that the overall incidence of pediatric CAs in EDs increased substantially over the past 5 yr, but without significantly higher survival outcomes.

Graphical Abstract

相似文献   
998.
We validated the basic life support termination of resuscitation (BLS TOR) rule retrospectively using Out-of-Hospital Cardiac Arrest (OHCA) data of metropolitan emergency medical service (EMS) in Korea. We also tested it by investigating the scene time interval for supplementing the BLS TOR rule. OHCA database of Seoul (January 2011 to December 2012) was used, which is composed of ambulance data and hospital medical record review. EMS-treated OHCA and 19 yr or older victims were enrolled, after excluding cases occurred in the ambulance and with incomplete information. The primary and secondary outcomes were hospital mortality and poor neurologic outcome. After calculating the sensitivity (SS), specificity (SP), and the positive and negative predictive values (PPV and NPV), tested the rule according to the scene time interval group for sensitivity analysis. Of total 4,835 analyzed patients, 3,361 (69.5%) cases met all 3 criteria of the BLS TOR rule. Of these, 3,224 (95.9%) were dead at discharge (SS,73.5%; SP,69.6%; PPV,95.9%; NPV, 21.3%) and 3,342 (99.4%) showed poor neurologic outcome at discharge (SS, 75.2%; SP, 89.9%; PPV, 99.4%; NPV, 11.5%). The cut-off scene time intervals for 100% SS and PPV were more than 20 min for survival to discharge and more than 14 min for good neurological recovery. The BLS TOR rule showed relatively lower SS and PPV in OHCA data in Seoul, Korea.

Graphical Abstract

相似文献   
999.
Megalocytic interstitial nephritis is a rare form of kidney disease caused by chronic inflammation. We report a case of megalocytic interstitial nephritis occurring in a 45-yrold woman who presented with oliguric acute kidney injury and acute pyelonephritis accompanied by Escherichia coli bacteremia. Her renal function was not recovered despite adequate duration of susceptible antibiotic treatment, accompanied by negative conversion of bacteremia and bacteriuria. Kidney biopsy revealed an infiltration of numerous histiocytes without Michaelis-Gutmann bodies. The patient''s renal function was markedly improved after short-term treatment with high-dose steroid.

Graphical Abstract

相似文献   
1000.
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