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   25725篇
  免费   2102篇
  国内免费   740篇
耳鼻咽喉   213篇
儿科学   704篇
妇产科学   3717篇
基础医学   3064篇
口腔科学   265篇
临床医学   1929篇
内科学   1414篇
皮肤病学   253篇
神经病学   693篇
特种医学   1124篇
外国民族医学   20篇
外科学   2179篇
综合类   3804篇
现状与发展   4篇
预防医学   887篇
眼科学   181篇
药学   1299篇
  18篇
中国医学   620篇
肿瘤学   6179篇
  2024年   60篇
  2023年   363篇
  2022年   713篇
  2021年   1102篇
  2020年   907篇
  2019年   791篇
  2018年   770篇
  2017年   932篇
  2016年   1044篇
  2015年   1012篇
  2014年   1681篇
  2013年   1807篇
  2012年   1409篇
  2011年   1446篇
  2010年   1185篇
  2009年   1134篇
  2008年   1283篇
  2007年   1236篇
  2006年   1232篇
  2005年   1074篇
  2004年   873篇
  2003年   757篇
  2002年   639篇
  2001年   570篇
  2000年   500篇
  1999年   387篇
  1998年   372篇
  1997年   326篇
  1996年   339篇
  1995年   302篇
  1994年   292篇
  1993年   216篇
  1992年   197篇
  1991年   194篇
  1990年   160篇
  1989年   144篇
  1988年   128篇
  1987年   105篇
  1986年   105篇
  1985年   118篇
  1984年   116篇
  1983年   71篇
  1982年   86篇
  1981年   94篇
  1980年   76篇
  1979年   69篇
  1978年   48篇
  1977年   43篇
  1976年   33篇
  1975年   7篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
101.
The objective of this study was to investigate the effect of arsenic trioxide (As(2)O(3)) on topoisomerase II levels using western blotting method on MDAH 2774 ovarian carcinoma cell culture. Experimental designs were established to determine the cytotoxic effects of As(2)O(3) on MDAH 2774 cells and the IC50 (fatal dose for the 50% of cells) value. Cytotoxicity experiments were carried out using various concentrations of As(2)O(3). The 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) and trypan blue dye-exclusion tests were used to evaluate cytotoxicity. Topoisomerase II expressions were investigated using western blotting method with various concentrations of As(2)O(3). Densitometric analysis of topoisomerase 2 bands was carried out using Quantity One 1-D analysis software (Bio-Rad USA, Life Science Research, Hercules, CA). IC50 value of As(2)O(3) was found to be 5 x 10(-6) M for MDAH 2774 cells. When the bands were evaluated, it was observed that there was a decrease in topoisomerase II levels in MDAH 2774 cells with increasing concentrations of As(2)O(3). It was also observed by the densitometric analysis that topoisomerase II expression ratios of MDAH 2774 cells were decreased by approximately 50% at this concentration. Topoisomerase II levels were significantly decreased with the increasing concentrations of As(2)O(3). Inhibition of topoisomerase II enzyme was one of the antiproliferative influence mechanisms of As(2)O(3).  相似文献   
102.
103.
目的:探讨胆固醇酯转运蛋白(CETP)在PCOS患者中的基因多态性和血脂、性激素的关系,以进一步认识PCOS脂代谢的特点。方法:应用PCR酶切方法检测108例PCOS患者及60例对照组的CETPTaqIB位点基因多态性。结果:CETPTaqIB基因频率及基因型分布在两组间分布差异无显著性。结论:CETPTaqIB基因多态性影响PCOS患者的HDLC水平,该基因在PCOS患者分布与正常人群分布无差异性。  相似文献   
104.
Carcinoma of the papilla of Vater is classified as periampullary cancer representing 5% of all gastrointestinal tract malignancies. Early and accurate diagnosis is important for those patients with a tumor of the papilla, as the prognosis is more favorable than in other periampullary neoplasms. Endoscopically obtained biopsies from suspicious papillae can detect an early tumor, although even for skilled pathologists it is often difficult to differentiate carcinomas from noninvasive lesions on the basis of forceps biopsies. The purpose of this study was to assess the preoperative diagnostic accuracy of duodenoscopy appearance and biopsy in all cases with suspicion of tumor. Thirty patients with suspicion of carcinoma of the papilla of Vater and with final diagnosis established by pancreatoduodenectomy were included in this retrospective study. In each case, a comparison was made between endoscopic biopsy and duodenoscopic appearance. Duodenoscopic appearance sensitivity and accuracy for malignancy were 86% and 83%, respectively, whereas endoscopic biopsy sensitivity and accuracy were 65% and 67%, respectively. Although preoperative diagnosis of carcinoma of the papilla of Vater is useful for making therapeutic decisions, the diagnostic value of the endoscopic appearance was superior to endoscopic biopsy in this series. Presented at the 2003 American Hepato-Pancreato-Biliary Association Congress, Miami, Florida, February 27-March 3, 2003. Supported by FADA-CAPES/PROP 200J (M.L.D.).  相似文献   
105.
卵巢癌中蛋白激酶C的表达及其临床意义   总被引:2,自引:0,他引:2  
目的 探讨上皮性卵巢癌组织蛋白激酶C (proteinkinaseC ,PKC)的表达和化疗耐药的关系 ,以及与P -糖蛋白 (P -gp)的相关性。方法 用免疫组化S -P法检测 35例卵巢上皮性肿瘤组织、 2 0例卵巢良性肿瘤组织和 2 0例正常卵巢组织中PKC和P -gp的表达 ,并进行相关临床因素分析。结果 ①PKC、P -gp在卵巢恶性肿瘤中的表达明显高于在良性及正常组织中的表达 ;并且PKC和P -gp的表达有相关性 (P <0 0 5 ) ;②卵巢癌PKC的表达与临床病理因素无直接关系 ;③恶性肿瘤中 ,初治和复发的PKC表达阳性率分别为 34 8%和 75 % ;④化疗对PKC表达阳性和阴性卵巢癌患者的有效率分别为 2 3 5 %、 6 6 7% (P <0 0 5 ) ;⑤PKC表达阴性患者的预后优于阳性者 (P =0 0 39)。结论 PKC表达与卵巢癌组织化疗耐药明显相关 ,可能在P -gp介导的卵巢癌多药耐药中起重要作用。  相似文献   
106.
超声心动图诊断原发性心脏肿瘤   总被引:1,自引:1,他引:0  
目的:探讨原发性心脏肿瘤超声心动图(ECG)特征。方法:利用ECG检查42例心脏肿瘤。其中粘液瘤38例,恶性肉瘤2例,均经手术病理证实。横纹肌瘤2例,经随访证实。结果:ECG对38例粘液瘤,2例横纹肌瘤全部做出正确诊断。2例恶性肿瘤提示相应部位占位病变。粘液瘤多发生在左房,有明确的瘤蒂,肿瘤回声稀疏,活动度大。恶性肿瘤回声较强、无蒂,活动度小。横纹肌瘤多发生在室壁心肌内,呈结节状,与正常心肌间有明确的界限。结论:ECG对原发心脏肿瘤的诊断具有重要意义,可初步区分良、恶性肿瘤。  相似文献   
107.
Zusammenfassung Im Rahmen einer retrospektiven Untersuchung wurden 50 Resektionen wegen primärer Lebermalignome, die vom 1. 6. 1979 bis zum 31. 12. 1991 an der Chirurgischen Universitätsklinik Köln durchgeführt wurden, analysiert. Die Resektionsrate betrug 28 %. Die Kliniksletalität betrug insgesamt 22 % und konnte in den letzten 5 Jahren auf 4% gesenkt werden. Die Ein-, Dreiund Fünfjahresüberlebensraten betrugen unter Einschluß der Kliniksletalität 55%, 30% und 24%. Wichtigster Prognosefaktor war die chirurgische Radikalität. In einer Literaturanalyse wurden die Ergebnisse von 8725 Leberresektionen wegen primärer Lebermalignome, die zwischen 1980 bis 1992 publiziert wurden, untersucht. Die Resektionsrate betrug im Durchschnitt 32 ± 17%. Die Kliniksletalität konnte von 15 ± 5% (Resektionen vor 1970) auf 6 ± 2% (Resektionen nach 1980) gesenkt werden. Die Ein-, Drei- und Fünfjahresüberlebensraten betrugen 66 ± 17%, 39 ± 15% und 27 ± 10%. Bis auf eine geringere Kliniksletalität asiatischer Studien (4 % vs. 7%) waren die Resektionsraten und Langzeitergebnisse von asiatischen, amerikanischen und europäischen Studien durchaus vergleichbar. Die Langzeitprognose wird in erster Linie durch die erreichte chirurgische Radikalität sowie die Größe und Ausdehnung des Tumors zum Zeitpunkt der Resektion beeinflußt. Die Effektivität adjuvanter Therapien ist noch nicht ausreichend untersucht.
Liver resection for primary liver tumors. Our own results and an analysis of the literature
In a retrospective study we analysed 50 resections for primary liver tumors performed between 1 July 1979 and 31 December 1991 at the Department of Surgery of the University of Cologne. The mean resectability rate was 28 %. Hospital mortality after resection was 22% and could be reduced to 4% during the last 4 years. The overall survival rates after 1, 3 and 5 years were 55%, 30% and 24% respectively. The surgical radicality is the most important prognostic factor. In a review of the literature the results of 8,725 resections for primary liver malignancies published between 1980 and 1992 were analyzed. The mean resectability rate was 32 ± 17%. The hospital mortality after resection could be reduced from 15 ± 5% (resections before 1970) to 6 ± 2 % (resections after 1980). The overall survival rates after 1, 3 and 5 years were 66 ± 17%, 39 ± 15% and 27 ± 10%, respectively. Apart from a lower hospital mortality in Asian studies (4 % vs. 7 %) the resection rates and long-term results of Asian, American and European studies were similar. Long-term prognosis predominantly depended on the surgical radicality and on the size and extension of the tumor at the point of resection. The effectivity of an adjuvant tumor therapy is not analyzed sufficiently.
  相似文献   
108.
本资料对93例不同性质的卵巢肿瘤细胞DNA及RNA含量进行了定量研究,其中50例良性、43例恶性。并对患者进行1~5年的随访。结果是卵巢良性肿瘤的异倍率(假阳性)为44%,恶性肿瘤异倍率为86.0%。以“标准DI”及“标准RI”为指标判断卵巢肿瘤性质的准确率较以“异倍性”为高,且双指标同时应用高于任一单指标:对卵巢良恶性肿瘤的诊断准确率分别为90%和95.3%。提出“标准DI”和“标准RI”是判断卵巢肿瘤性质的理想指标。且DNA及RNA含量与卵巢癌预后有密切关系。  相似文献   
109.
Primary and transplanted ENU induced rat tumors in neurooncology   总被引:1,自引:0,他引:1  
In neurooncology transplanting, tumors can be used for many purposes e.g. to solve questions concerning the etiology and pathogenesis of such tumors or their management. Experimentally induced and transplanted tumors of the nervous system become reproducible in their morphology and growth parameters after about 12 subsequent intracerebral passages. During the period from the first to the 12th intracerebral generations, a simplification of the histology and a reduction of the induction times take place. Nowadays the growth behavior of such tumors can be followed by imaging methods such as MRI if specially adapted to small animals. Our results are based on the investigation of over 2350 experimentally induced tumors of the central and peripheral nervous system that were diagnosed according to the rules of human and rodent brain tumor classification and various subgroups of this sample, analyzed by electron microscopy, postmortal angiography and MRI.  相似文献   
110.
Metastatic carcinoma of the spleen occurs in a setting of widespread malignant disease. Solitary parenchymal splenic metastasis of ovarian carcinoma is rare. We report a case of a 59-year-old woman who presented with an elevated serum CA125 level due to a solitary splenic metastasis after a long disease-free period. She was treated with laparoscopic splenectomy followed by chemotherapy. The literature contains 16 cases of solitary parenchymal splenic metastasis of ovarian carcinoma. Our case is the third case that was treated with laparoscopic splenectomy. We review the literature, and we focus on the laparoscopic approach in managing these cases.  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