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   31944篇
  免费   2799篇
  国内免费   1463篇
耳鼻咽喉   102篇
儿科学   334篇
妇产科学   147篇
基础医学   2532篇
口腔科学   600篇
临床医学   2811篇
内科学   5947篇
皮肤病学   213篇
神经病学   1788篇
特种医学   1177篇
外国民族医学   45篇
外科学   4024篇
综合类   6031篇
现状与发展   2篇
预防医学   1020篇
眼科学   147篇
药学   2237篇
  30篇
中国医学   1431篇
肿瘤学   5588篇
  2024年   88篇
  2023年   531篇
  2022年   1006篇
  2021年   1339篇
  2020年   1193篇
  2019年   986篇
  2018年   895篇
  2017年   1085篇
  2016年   1227篇
  2015年   1228篇
  2014年   1919篇
  2013年   2062篇
  2012年   1741篇
  2011年   1838篇
  2010年   1462篇
  2009年   1435篇
  2008年   1536篇
  2007年   1769篇
  2006年   1432篇
  2005年   1343篇
  2004年   1083篇
  2003年   910篇
  2002年   878篇
  2001年   865篇
  2000年   763篇
  1999年   612篇
  1998年   552篇
  1997年   502篇
  1996年   475篇
  1995年   468篇
  1994年   436篇
  1993年   330篇
  1992年   292篇
  1991年   269篇
  1990年   237篇
  1989年   201篇
  1988年   196篇
  1987年   147篇
  1986年   117篇
  1985年   149篇
  1984年   119篇
  1983年   73篇
  1982年   79篇
  1981年   73篇
  1980年   66篇
  1979年   41篇
  1978年   30篇
  1977年   29篇
  1976年   28篇
  1975年   24篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Ma  K. -C.  Lundberg  P. O.  Lilja  A.  Olsson  Y. 《Acta neuropathologica》1992,83(4):434-439
Summary The cerebral changes are described in a woman of 54 who suffered from Binswanger's encephalopathy: there were no signs or symptoms of chronic arterial hypertension. The disease presented as dementia of about 3 years duration. Computed tomography of the brain 2. 5 years before her death showed bilateral widespread hypodense lesions in the cerebral white matter. She died of an asthmatic attack. Autopsy disclosed extensive bilateral degeneration of the central white matter, lacunes and gliosis. Severe obliterative arteriolosclerosis occurred in the meningeal vessels and those supplying the affected parts of the brain. Light microscopy showed that the most severe lesions occurred in the arterioles. Immunohistochemistry demonstrated profound extravasation of plasma proteins chiefly albumin, indicating dysfunction of the blood-brain barrier. Thus, the lesions characteristic of Binswanger's encephalopathy may develop in the absence of chronic arterial hypertension. Additional pathogenic factors, possibly genetic predisposition to vascular injury may play a role in the development of this condition.Supported by grants from the Swedish Medical Research Council, Project No 12X-03020 and 1987 Års Stiftelse för Strokeforskning  相似文献   
152.
Neuronal plasticity can manifest itself in alterations in the sensitivity of memory to the effects of drugs. After the production of a brain lesion, the memory processing of a passive-avoidance task in mice gradually becomes sensitive to the effect of morphine, i.e., an improvement in retention performance is seen after 6 weeks, but not after 1 or 2 weeks. The results presented demonstrate that, even if they lead to no discernible changes in behaviour, plastic processes can still be detected by means of behavioural tests.  相似文献   
153.
The effect of acute and sequential volaemic changes on the gastroduodenal flow of saline was assessed in 23 anaesthetized dogs following two different experimental protocols. Hypervolaemia, by i. v. infusion of saline, induced a gradual decrease on gastroduodenal flow which amounted to 76% below control values (P < 0.001) when volaemic expansion attained 5% of body weight. This effect was volume dependent (17% increase on gastroduodenal flow per volume of infused saline equivalent to 0.5% of body weight, P < 0.001), lasted for at least 90 minutes after infusion was completed and was also obtained by expanding previously bled animals. Hypovolaemia due to bleeding was followed by an increase on gastroduodenal flow of about 88% above control values (P < 0.05) when haemorrhage was equal to 3% of body weight. This effect was also volume dependent (23 % increase on gastroduodenal flow per volume of blood shed equivalent to a 0.5% of body weight, P < 0.01) and was reversed after blood volume was restored. These modifications in the resistance of the gastroduodenal segment to the flow of liquid due to acute volaemic changes suggest that the extracellular fluid volume modulates the contractile activity of the gastroduodenal portion of the gut possibly to set a gastroduodenal handling of liquid adequate to cope with volaemic imbalances.  相似文献   
154.
目的研究T3期胃癌CD34与胃癌新生血管形成及淋巴结转移的关系.方法随机选取胃癌手术标本41例,其中T3N0M020例,T3N1M021例,分别进行特异性抗体免疫组化染色,并采用Image Pro Plus 5.0图像软件分析数据,计算胃癌组织CD34微血管密度(MVD)和其他相关抗体(CD44、Ⅳ型胶原、层黏蛋白)的表达,并进行统计学分析.结果CD34 MVD计数(CD34表达强度),在T3N0M0和T3N1 M0肿瘤组分别为43.10±18.22和56.24±28.36,两组比较有显著差异(P<0.05);CD44、Ⅳ型胶原、层黏连蛋白的表达强度,T3N0M0和T3N1M0肿瘤组比较无显著差异(P>0.05).结论CD34与T3期胃癌组织新生血管形成及淋巴结转移的关系密切,可作为诊断T3期胃癌淋巴结转移的参考指标.  相似文献   
155.
背景与目的:由于缺乏特异性临床和影像表现,肿块型中枢神经系统原发性血管炎(primary angiitris of central nervous system,PACNS)常被误诊为胶质瘤.本文旨在探讨肿块型PACNS的诊断与鉴别诊断。方法:回顾性分析手术治疗的37例肿块型PACNS患者的临床及影像表现。结果:85.3%的患者出现局灶性神经功能减退,55.9%患者有不同程度皮层高级功能减退症状。70.6%的颅内病变累及脑皮层:73.5%患者的正常区域脑血管周围间隙增宽,其中76%出现血管强化;病变出现特征性的“C”形强化。结论:局灶性神经功能和高级功能减退、病变累及皮层和“C”形强化等特征.有助于诊断肿块型PACNS。  相似文献   
156.
In the period from January 1, 1976 to December 31, 1988, we reviewed the charts of 33 patients treated for carcinoma of the thyroid at Howard University Hospital. The three non-black patients (two Whites and one Pakistani) were excluded from the study. There were 19 females and 11 males. Of the 30 cases elevated, 10 were papillary, 7 were follicular variant of papillary, 8 were follicular, 3 were undifferentiated (anaplastic), and 2 were medullary. Ten patients had either distant metastasis (Hoffman, South Med J 80:741, 1987) or locally advanced disease in the neck (Woolner et al., Am J Surg 102:354, 1961.) at the time of diagnosis. The treatment of these lesions depended on, among other variables, the cell type, the extent of the lesion, and the personal preference of the attending surgeon. Carcinoma of the thyroid remains an uncommon lesion in Black patients. Because of its rarity, the diagnosis may often be delayed and, as a result, patients may first come to attention with a more advanced stage of this disease. To prevent this occurrence, a high index of suspicion must be maintained for all thyroid nodules, and appropriate diagnostic steps taken. Diagnostic and treatment options are discussed.  相似文献   
157.
158.
In a 48-year-old Japanese man there was an uncontrollable and recurrent bleeding from a gastric ulcer and laparoscopic surgery was done. Two cannulae were placed in the gastric cavity through the abdominal wall and suture ligation of the bleeding vessel at the posterior wall of the stomach was done under videovisual control with endoscopic guidance. The bleeding ceased, complications were nil, and he remains well.This article reports on surgery done to repair uncontrollable, recurrent bleeding from a gastric ulcer. Two cannulae were placed in the gastric cavity through the abdominal wall and suture of the vessel at the posterior wall of the stomach was done with videovisual control and endoscopic guidance. This approach is concluded to have supplied minimal-access surgery, cost effectiveness, early discharge, less pain, and doctor-patient satisfaction.  相似文献   
159.
李垚  吴坤  赵艳  于卫平 《中国公共卫生》2003,19(11):1290-1292
目的 探讨维生素E琥珀酸酯 (VES)诱导人胃腺癌SGC -790 1细胞凋亡的死亡受体 (Fas)信号转导途径。方法 人胃腺癌SGC -790 1细胞经不同剂量VES(5,10 ,2 0 μg/ml)处理 ,同时做琥珀酸、维生素E和空白对照 ,采用DAPI(4,6-贰脒基 -2 -苯基吲哚 )荧光染色法观察细胞凋亡情况 ,用WesternBlot法检测Fas、带有死亡结构域的Fas相关蛋白 (FADD)和天冬氨酸特异性半胱氨酸蛋白酶 (caspase -8)蛋白表达情况 ,Fas和FADD反义寡聚核苷分别转染SGC -790 1细胞后 ,用荧光法检测caspase -8活性。 结果 经VES处理后的细胞DAPI染色可见凋亡的形态学改变 ,2 0 μg/mlVES处理 48h后的细胞凋亡率为 89.6% ;VES处理 48h后Fas、FADD和caspase -8蛋白表达明显增加 ,且呈剂量 -效应关系 ;阻断Fas可明显抑制FADD蛋白表达 ,Fas和FADD反义寡聚核苷转染细胞后caspase -8活性明显降低 (P <0 .0 1) ,其中阻断Fas的效果高于阻断FADD。结论 维生素E琥珀酸酯诱导人胃腺癌SGC -790 1细胞凋亡过程中启动了Fas信号转导途径 ,VES启动Fas后 ,FADD将Fas和caspase -8联接起来 ,活化caspases级联反应 ,从而构成Fas/FADD/caspase -8的凋亡信号途径  相似文献   
160.
目的 提高胃上部癌外科治疗水平。方法 对94例胃上部癌采用了经腹正中切口或合并切除剑突及左第7~9肋弓软骨入路,行近端胃或全胃切除术。结果 全组病例发生吻合口瘘1例,食管断端癌残留3例和肺部感染8例,无肋软骨炎及胸膜损伤所致血气胸发生。结论 胃上部癌经腹入路暴露良好,创伤小,痛苦少,适用于食管无浸润或浸润小于1cm的胃上部癌的患者。  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