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   241905篇
  免费   20593篇
  国内免费   14332篇
耳鼻咽喉   2174篇
儿科学   3035篇
妇产科学   4879篇
基础医学   28293篇
口腔科学   4208篇
临床医学   30842篇
内科学   39827篇
皮肤病学   2816篇
神经病学   13535篇
特种医学   8535篇
外国民族医学   96篇
外科学   26653篇
综合类   34081篇
现状与发展   48篇
一般理论   45篇
预防医学   15092篇
眼科学   6674篇
药学   24192篇
  164篇
中国医学   10914篇
肿瘤学   20727篇
  2024年   697篇
  2023年   3482篇
  2022年   8675篇
  2021年   11378篇
  2020年   8389篇
  2019年   7548篇
  2018年   7990篇
  2017年   6970篇
  2016年   6665篇
  2015年   10094篇
  2014年   12694篇
  2013年   11884篇
  2012年   17536篇
  2011年   19218篇
  2010年   11721篇
  2009年   9379篇
  2008年   12767篇
  2007年   12804篇
  2006年   12366篇
  2005年   12439篇
  2004年   8602篇
  2003年   7641篇
  2002年   6614篇
  2001年   5988篇
  2000年   6108篇
  1999年   6409篇
  1998年   3650篇
  1997年   3672篇
  1996年   2793篇
  1995年   2584篇
  1994年   2234篇
  1993年   1499篇
  1992年   2294篇
  1991年   1996篇
  1990年   1665篇
  1989年   1455篇
  1988年   1264篇
  1987年   1176篇
  1986年   941篇
  1985年   748篇
  1984年   491篇
  1983年   381篇
  1982年   225篇
  1981年   201篇
  1980年   191篇
  1979年   243篇
  1978年   141篇
  1977年   112篇
  1976年   97篇
  1974年   116篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Objective To compare the clinical efficacy and complications of transurethral resection of the prostate (TURP),transurethral vapor-resection of the prostate (TUVP) and plasmakinetic energy transurethral resection of the prostate (PKRP) for benign prostatic hypertrophy (BPH).Methods A total of 545 patients with BPH were enrolled from December 1999 to Januare 2004.  相似文献   
992.
We report a 41-year-old woman with complex reflex epilepsy in which seizures were induced exclusively by the act of tooth brushing. All the attacks occurred with a specific sensation of sexual arousal and orgasm-like euphoria that were followed by a period of impairment of consciousness. Ictal EEG demonstrated two events of epileptic seizure that were provoked after tooth brushing for 38 and 14 seconds, respectively. The interictal EEG showed epileptiform discharges over the right anterior temporal region and interictal single photon emission computed tomography (SPECT) scan showed relative hypoperfusion in the uncus of right temporal lobe. Brain magnetic resonance imaging (MRI) revealed right hippocampal atrophy. We suggest that tooth-brushing epilepsy, especially with sexual ictal manifestations, may provide insight into the cerebral pathophysiology at the right temporolimbic structure.  相似文献   
993.
寒冷干燥地区平时火器伤的早期处理   总被引:3,自引:3,他引:0  
目的 探讨寒冷干燥地区平时火器伤伤情特点与早期救治方法。方法 对 1991年 1月— 2 0 0 2年 12月间 40例火器伤病人的临床救治进行回顾分析。结果  2 4例枪伤中 ,2 0例一期缝合伤口 ,均一期愈合 ,另外 4例只清创未一期缝合的伤口 ,3例愈合 ,1例感染 ;4例骨折内固定均愈合良好 ,无骨髓炎发生。 16例炸伤病人局部软组织损伤及污染比枪弹伤重 ,14例一期缝合伤口中 ,10例一期愈合 ,4例感染 ,骨折内固定 2例 ,均愈合良好 ,无骨髓炎发生。结论 寒冷干燥地区火器伤早期伤道清创时限可适当延长 ,在平时火器伤的救治中 ,对软组织条件较好的创面 ,早期清创后可一期闭合伤口和骨折内固定 ,这样可减少感染和伤残 ,促进康复  相似文献   
994.
通脉养心口服液与通脉养心丸药理作用比较   总被引:2,自引:1,他引:1       下载免费PDF全文
对通脉养心口服液及丸剂进行了药理作用的比较,结果表明,2种剂型基本具有相同的心血管药理作用,但在作用强度上不完全相同,在抑制心肌缺血猎ST段抬高及提高减压缺氧耐力上,口服液较丸剂作用稍强,在抑制大鼠实验性血栓形成上,丸剂比口服液作用稍强。  相似文献   
995.
OBJECTIVE: In 1991, a randomized study was published and demonstrated that use of nonsurgical therapy (chemoradiation) provided similar survival to total laryngectomy (the gold standard) for patients with advanced-stage laryngeal cancer. The purpose of this study was to assess how treatment of advanced laryngeal cancer was influenced by such developments in non-surgical therapy. STUDY DESIGN: Patterns of care study using National Cancer Database (1985-2001). RESULTS: The percentage of advanced-stage patients treated with chemoradiation increased from 8.3% to 20.8% while the proportion treated with radiation alone decreased from 38.9% to 23.0%. Use of chemoradiation increased at a significantly faster rate after the 1991 publication at both community cancer centers and teaching research facilities. The use of total laryngectomy decreased slightly during this period. CONCLUSIONS: The use of chemoradiation increased after the 1991 publication. It was impossible to determine from the NCDB whether additional patients who could benefit from chemo-RT were not offered or did not complete this treatment option. We recommend that treatment recommendations discussed at tumor boards be recorded in cancer registries.  相似文献   
996.
OBJECTIVE: This study compares the efficacy of endolymphatic mastoid shunt (EMS) versus endolymphatic sac decompression (ESD) without sac incision for the treatment of Ménière's disease. STUDY DESIGN AND SETTING: The AAO-HNS Guidelines for the Diagnosis and Evaluation of Therapy in Ménière's disease were used to retrospectively identify suitable candidates for the study. All patients who failed medical management and underwent either endolymphatic-mastoid shunt (EMS) (n = 88) or endolymphatic sac decompression (ESD) (n = 108) were selected for review using the AAO-HNS guidelines. The study was carried out at a tertiary care neurotology private practice. RESULTS: EMS and ESD were equally effective in reducing the incidence and severity of vertigo attacks with significant improvement in 67 percent and 66 percent of patients, respectively. CONCLUSION: Both EMS and ESD are effective, nondestructive alternatives for patients who have failed medical management of Ménière's disease with similar long-term hearing outcomes. SIGNIFICANCE: This is the only study within the same institution using AAO-HNS guidelines comparing EMS versus ESD.  相似文献   
997.
目的探讨维吾尔族和汉族弱精子症病人精子mtDNA~(4977bp)缺失的相关性。方法本文采用聚合酶链反应(PCR)技术对60例标本分两组,维、汉各30例,其中精子活力正常标本(对照组)和弱精子症患者(观察组)各15例进行了精子线粒体DNA(mtDNA)缺失的研究。结果发现15例做内对照的维族精子活力正常人中仅有3例(20%)有mtDNA~(4977bp)缺失;而15例维吾尔族弱精子症患者中有10例(67%) mtDNA~(4977bp)缺失;两组4977bp缺失频率比较有显著性差异(P<0.05)。15例做内对照的汉族精子活力正常标本中无mtDNA~(4977bp)缺失;15例汉族弱精子症患者中有12例(80%)mtDNA~(4977bp)缺失。两组4977bp缺失频率比较差异有显著性(P<0.05)。同时发现维吾尔族男性不育症与汉族男性不育症mtDNA~(4977bp)缺失频率无显著性差异。结论维吾尔族和汉族mtDNA~(4977bp)缺失在弱精子症的发病中可能起重要作用。  相似文献   
998.
999.
The nuclease activity of 1,10-phenanthroline-copper ion can be targeted to specific DNA sequences by attachment of the ligand to the 5' end of complementary deoxyoligonucleotides via a phosphoramidate linkage. To synthesize the adduct, the phosphorimidazolide of the deoxyoligonucleotide is prepared using a water-soluble carbodiimide and is then coupled to 5-glycylamido-1,10-phenanthroline. After hybridization to the target DNA, sequence-specific cleavage is observed upon the addition of cupric ion and 3-mercaptopropionic acid. Two methods of assaying the cutting of the operator sequence of the lac operon have been employed using the oligonucleotide 5'-AATTGTTATCCGCTCACAATT-3' representing sequence positions 21-1 of the template strand. In the first, the single-stranded DNA of the phage M13mp8 was the target, and cuts were detected using a primer-extension assay. In the second, the substrate was an EcoRI fragment 3' labeled in the nontemplate strand. After denaturation and reannealing to the oligonucleotide-1,10-phenanthroline adduct, cupric ion and 3-mercaptopropionic acid were added, and the products were analyzed directly on a sequencing gel. With the phenanthroline moiety attached to position 21 of the oligonucleotide carrier, cutting was observed at positions 20-25 using both assays.  相似文献   
1000.
Human lung cancers are divided into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) based on established criteria. SCLC differs from NSCLC by the expression of biomarkers, including creatine kinase-BB isoenzyme (EC 2.7.3.2). Subtypes of SCLC are referred to as classic and variant, both of which have elevated levels of creatine kinase-BB isoenzyme. We, therefore, applied 31P nuclear magnetic resonance spectroscopy to cell lines of classic SCLC, variant SCLC, and NSCLC human tumors, using continuous perfusion to identify any differences in the detectable levels of intracellular high-energy phosphate compounds. The spectra indicate that only the variant SCLC cells maintain high levels of phosphocreatine. Additionally, the classic SCLC cells express elevated levels of a diphosphodiester. Neither phosphocreatine nor diphosphodiesters are found in the NSCLC cell spectra.  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