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   29526篇
  免费   2961篇
  国内免费   1532篇
耳鼻咽喉   274篇
儿科学   350篇
妇产科学   501篇
基础医学   5905篇
口腔科学   574篇
临床医学   1539篇
内科学   3526篇
皮肤病学   609篇
神经病学   1319篇
特种医学   469篇
外国民族医学   15篇
外科学   1946篇
综合类   4887篇
现状与发展   6篇
预防医学   803篇
眼科学   263篇
药学   2893篇
  2篇
中国医学   703篇
肿瘤学   7435篇
  2024年   70篇
  2023年   429篇
  2022年   879篇
  2021年   1217篇
  2020年   962篇
  2019年   769篇
  2018年   671篇
  2017年   783篇
  2016年   765篇
  2015年   1081篇
  2014年   1442篇
  2013年   1491篇
  2012年   1382篇
  2011年   1760篇
  2010年   1528篇
  2009年   1614篇
  2008年   1637篇
  2007年   1719篇
  2006年   1564篇
  2005年   1516篇
  2004年   1446篇
  2003年   1381篇
  2002年   1198篇
  2001年   1162篇
  2000年   1037篇
  1999年   851篇
  1998年   725篇
  1997年   638篇
  1996年   507篇
  1995年   396篇
  1994年   246篇
  1993年   189篇
  1992年   112篇
  1991年   93篇
  1990年   53篇
  1989年   55篇
  1988年   64篇
  1987年   44篇
  1986年   50篇
  1985年   58篇
  1984年   60篇
  1983年   33篇
  1982年   49篇
  1981年   46篇
  1980年   45篇
  1979年   32篇
  1978年   34篇
  1977年   36篇
  1976年   23篇
  1973年   15篇
排序方式: 共有10000条查询结果,搜索用时 112 毫秒
121.
目的探讨p38丝裂原活化蛋白激酶(p38MAPK)在链脲菌素诱导的糖尿病大鼠神经病理性痛中的作用。方法雌性Wistar大鼠31只,3月龄,体重180~220g,随机分为3组:对照组(C组,n=10)、糖尿病神经病理性痛组(D组,n=11)和p38MAPK抑制剂组(Ⅰ组,n=10)。D组、Ⅰ组单次腹腔注射链脲菌素65mg/kg制备糖尿病模型。糖尿病模型制备成功后,Ⅰ组尾静脉注射p38MAPK抑制剂SB203580 0.5mg/kg,1次/周,连续4周;C组和D组尾静脉注射等体积的生理盐水。给药4周后,测定机械缩足反应阈值(MWT)、左侧坐骨神经传导速率(NCV)、背根神经节(DRG)和脊髓的磷酸化p38MAPK水平。结果与C组比较,D组、Ⅰ组MWT下降,NCV减慢,伴有脱髓鞘现象,DRG和脊髓的磷酸化p38MAPK水平升高;与D组比较,Ⅰ组MWT升高,NCV增快,脱髓鞘程度减轻,DRG和脊髓的磷酸化p38MAPK水平下降。结论p38MAPK信号转导通路参与了糖尿病大鼠神经病理性痛的形成。  相似文献   
122.
Background Gene therapy by adenovirus-mediated wild-type p53 gene transfer has been shown to inhibit lung cancer growth in vitro, in animal models, and in human clinical trials. The antitumor effect of selective cyclooxygenase (COX)-2 inhibitors has been demonstrated in preclinical studies. However, no information is available on the effects of p53 gene therapy combined with selective COX-2 inhibitor on COX-2 gene expression and growth inhibition of human lung cancer cells. Methods We evaluated the effects of recombinant adenovirus-p53 (Adp53) gene therapy combined with selective CADX-2 inhibitor on the proliferation, apoptosis, cell cycle arrest of human lung adenocarcinoma A549 cell line, and the effects of tumor suppressor exogenous wild type p53 on COX-2 gene expression. Results Ad-p53 gene therapy combined with selective COX-2 inhibitor celecoxib shows significant synergistic inhibition effects on the growth of human lung adenocarcinoma A549 cell line. Exogenous p53 gene can suppress COX-2 gene expression. Conclusions Significant synergistic inhibition effects of A549 cell line by the combined Ad-p53 and selective COX-2 inhibitor celecoxib may be achieved by enhancement of growth inhibition, apoptosis induction and suppression of COX-2 gene expression. This study provides first evidence that the administration of p53 gene therapy in combination with COX-2 inhibitors might be a new clinical strategy for the treatment or prevention of NSCLC.  相似文献   
123.
Molecular staging of head and neck squamous carcinoma   总被引:3,自引:0,他引:3  
The staging system of head and neck cancer is a Tumor-Node-Metastases system that was developed by the American Joint Committee on Cancer. The stage of the head and neck cancer defines the extent of the lesion and is determined by physical examination, radiologic studies, and pathologic examination. Accurate staging of head and neck cancer is critical since it will determine the treatment modalities used to cure the disease. Recent advances in the field of molecular genetics have allowed clinicians to detect occult cancer cells previously missed by physical examination and standard histopathologic techniques. Molecular assays are 500 times more sensitive in identifying cancer cells than standard techniques and provide more objective analyses with fewer sampling errors. Consequently, these techniques are currently being used to perform molecular staging of head and neck cancer patients. Preliminary results show that molecular staging will accurately identify those patients at significantly increased risk for recurrence of their head and neck cancer.  相似文献   
124.
We report on the clinical and pathologic findings in a girl with isochromosome 18q (46, XX,i(18q)) who had combined manifestations of monosomy 18p and trisomy 18q. Major congenital anomalies included premaxillary agenesis, alobar holoprosenphaly, double Outlet right ventricle, DiGeorge anomaly and streak ovaries. The clinical spectrum in i(18q) is very broad. © 1993 Wiley-Liss, Inc.  相似文献   
125.
应用抗增殖细胞核抗原和抑癌基因p53蛋白的单克隆抗体对37例放疗或化疗后的肺癌进行了检测,并与未经术前治疗的肺癌组织进行对照,部分组织进行了超微结构观察。结果发现:(1)放疗或化疗对肺癌组织细胞浆及胞核有不同程度的破坏。(2)放、化疗后组织(除分化型腺癌外)PCNA指数下降明显(P<0.01或P<0.05)。(3)放疗后肺癌组织p53表达率减低,但化疗后变化不明显。  相似文献   
126.
127.
Summary In Denmark it is legal to grow opium poppies for the production of poppy seeds and until 1986 for decoration purposes, too. Danish poppy capsules contain 0.3–5 mg morphine per capsule and the content of morphine in opium exuded from the capsules may amount to 24%. This has resulted in misuse as both fresh and dried poppy capsules have been used for the production of opium tea. During the period 1982–1985, seven casualties occurred among drug addicts in Denmark which were solely or partly caused by these opium poppies.  相似文献   
128.
Summary Spirally cut strips of human saphenous veins preincubated with 3H-noradrenaline were superfused in the presence of corticosterone and, unless stated otherwise, of cocaine or desipramine. Tritium overflow was stimulated electrically (2 Hz). Adrenaline (in the presence of rauwolscine), isoprenaline and the preferential 2-adrenoceptor agonist procaterol concentration-dependently increased the electrically evoked tritium overflow. Prenalterol, a -adrenoceptor agonist with moderate preference for 1-adrenoceptors, was ineffective. The concentration-response curve of isoprenaline was shifted to the right by the nonselective -adrenoceptor antagonist propranolol and by the preferential 2-adrenoceptor antagonist ICI 118,551, but was not affected by the 1-selective antagonist atenolol. In experiments on strips preexposed to adrenaline 10 nmol/l (i. e. a concentration higher than that which normally occurs in vivo) for 32 min in the absence of cocaine or desipramine, the electrically evoked 3H overflow was not affected 12 and 44 min after withdrawal of adrenaline, irrespective of whether propranolol was absent or present in the superfusion fluid. — In veins incubated with 3H-adrenaline, a considerable amount of the radioactivity was accumulated. During subsequent superfusion with 3H-adrenaline-free solution, electrical stimulation induced tritium overflow in a tetrodotoxin-sensitive manner. Propranolol failed to modify the evoked tritium overflow. — It is concluded that the sympathetic nerve fibres of the human saphenous vein are endowed with facilitatory presynaptic 2-adrenoceptors. These receptors do not seem to play a substantial role in a local adrenaline (previously taken up)-mediated positive feedback loop regulating noradrenergic transmission, at least under the present in vitro conditions.This study was supported by a grant of the Deutsche Forschungsgemeinschaft Send offprint requests to M. Göthert  相似文献   
129.
In order to clarify the etiology of a dose-related increase in the incidence of tubular cell adenocarcinomas of the kidney in male rats, the nephrotoxicity of p-dichlorobenzene (p-DCB) was investigated in a subchronic study. Groups of ten male and ten female Fischer 344 rats were dosed by gavage with 0 (controls), 75, 150, 300 or 600 mg p-DCB/kg/day in corn oil. Half of the animals were sacrificed after 4 weeks and the remainder after 13 weeks. Increased urinary LDH and epithelial cell excretion and exacerbation of hyaline droplet accumulation in the cytoplasm of renal cortical cells were observed in male rats over the entire dose range investigated. Tubular single cell necrosis, dilated tubules with granular cast formation in the outer zone of the medulla, were evident in male rats after 4 and 13 weeks of treatment with doses of 150–600 mg/kg/day. In female rats there was no indication of a nephrotoxic action of p-DCB. The effects on the kidney, both in their morphological characteristics and the fact that they occur exclusively in male animals, correspond to the light hydrocarbon nephropathy observed as a result of short-term treatment with a number of aliphatic and cyclic hydrocarbons. The development of cortical renal tumors seems to be associated with this kind of kidney damage which is unique to male rats. The literature on this subject generally regards these renal effects as not predictive for man.  相似文献   
130.
目的探讨SNHG6对急性心肌梗死(AMI)小鼠左心室心肌的影响。 方法将30只雄性C57/BL6小鼠构建成AMI小鼠后随机均分为AMI组、AMI+SNHG6组、AMI+miR-101-3p组、AMI+SNHG6+miR-101-3p组、AMI+miR-101-3p+TGFBR1组,另设正常小鼠6只为假手术组。qRT-PCR检测AMI小鼠SNHG6、miR-101-3p表达水平。心脏彩超检测各组小鼠左室射血分数(LVEF);马松和天狼星红染色法以及免疫组化分析各组小鼠左心室心肌纤维化变化。将H9C2细胞株分为阴性对照组(转染空质粒)、SNHG6组(转染质粒SNHG6)、miR-101-3p组(转染质粒miR-101-3p)。Western blotting检测各组TGFBR1蛋白表达;采用双荧光素酶报告基因法预测并验证SNHG6/miR-101-3p/TGFBR1荧光素酶活性及调控机制。 结果AMI小鼠较假手术组SNHG6表达显著增加,miR-101-3p降低(P<0.05)。与AMI组比较,AMI+SNHG6组小鼠LVEF降低,心肌纤维化程度加重(P<0.05);AMI+miR-101-3p组LVEF升高,心肌纤维化程度减轻(P<0.05)。AMI+SNHG6+miR-101-3p组较AMI+SNHG6组LVEF升高、心肌纤维化程度减轻(P<0.05),而AMI+miR-101-3p+TGFBR1组较AMI+miR-101-3p组LVEF降低、心肌纤维化程度加重(P<0.05)。双荧光素酶报告基因法验证显示,miR-101-3p组SNHG6、TGFBR1野生型质粒的荧光素酶活性较阴性对照组明显降低(P<0.05)。 结论SNHG6抑制miR-101-3p上调TGFBR1加重AMI小鼠左心室心肌纤维化。  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