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   32026篇
  免费   2684篇
  国内免费   1345篇
耳鼻咽喉   390篇
儿科学   593篇
妇产科学   573篇
基础医学   3907篇
口腔科学   567篇
临床医学   3398篇
内科学   5355篇
皮肤病学   743篇
神经病学   2128篇
特种医学   1056篇
外国民族医学   13篇
外科学   4085篇
综合类   4039篇
现状与发展   4篇
一般理论   19篇
预防医学   1914篇
眼科学   1147篇
药学   2565篇
  19篇
中国医学   1084篇
肿瘤学   2456篇
  2024年   61篇
  2023年   433篇
  2022年   934篇
  2021年   1387篇
  2020年   1031篇
  2019年   965篇
  2018年   1086篇
  2017年   955篇
  2016年   956篇
  2015年   1246篇
  2014年   1551篇
  2013年   1490篇
  2012年   2301篇
  2011年   2343篇
  2010年   1341篇
  2009年   1128篇
  2008年   1662篇
  2007年   1681篇
  2006年   1649篇
  2005年   1655篇
  2004年   1204篇
  2003年   1032篇
  2002年   918篇
  2001年   780篇
  2000年   794篇
  1999年   769篇
  1998年   439篇
  1997年   373篇
  1996年   287篇
  1995年   296篇
  1994年   238篇
  1993年   174篇
  1992年   304篇
  1991年   289篇
  1990年   278篇
  1989年   258篇
  1988年   222篇
  1987年   207篇
  1986年   200篇
  1985年   150篇
  1984年   108篇
  1983年   74篇
  1982年   50篇
  1981年   54篇
  1979年   75篇
  1978年   51篇
  1977年   53篇
  1974年   66篇
  1973年   60篇
  1972年   63篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
本文通过用四氧嘧啶复制小白鼠糖尿病模型,以血清中血糖及胰岛素水平为指标,研究了地黄合剂对高糖动物的降血糖作用。结果表明,注射四氧嘧啶前小白鼠血糖为173.47±5.23mg/100ml注射后血糖升高至419.78±22.70mg/100ml(P<0.01),差异有高度显著性。实验组服用地黄合剂后,血糖值从410.25±2739mg/100ml下降至313.51±29.39mg/100ml(P<0.05)差异有显著性。因而认为地黄合剂对于四氧嘧啶性糖尿病有显著的降血糖作用。  相似文献   
42.
Lymphoid clusters (LC) containing CD20-positive B cells in kidney allografts undergoing acute cellular rejection (ACR) have been identified in small studies as a prognostic factor for glucocorticoid resistance and graft loss. Allograft biopsies obtained during the first episode of ACR in 120 recipients were evaluated for LC, immunostained with CD20 antibody, and correlated with conventional histopathologic criteria, response to treatment and outcome. LC were found in 71 (59%) of the 120 biopsies. All contained CD20 positive B cells that accounted for 5-90% of the LC leukocyte content. The incidence of LC was highest in the patients who had no lymphoid depletion or had been treated with Thymoglobulin preconditioning (79% vs. 75%, respectively) compared to 37% in patients pretreated with Campath (p = 0.0001). Banff 1a/1b ACR were more frequent in the LC-positive than the LC-negative group (96% vs. 80%, respectively; p = 0.0051). With a posttransplant follow-up of 953 +/- 430 days, no significant differences were detected between LC-postitive and LC-negative groups in time to ACR, steroid resistance, serum creatinine and graft loss. CD20+LC did not portend glucocorticoid resistance or worse short to medium term outcomes. CD20+LC may represent a heterogenous collection in which there may be a small still to be fully defined unfavorable subgroup.  相似文献   
43.
目的探讨肾动脉狭窄支架植入术的临床疗效.方法1997年1月~2004年12月,我院行支架介入治疗肾动脉狭窄27例.对27例术前、术后及随访期内血压、肾功能以及生活质量进行评估,并与同期单纯药物治疗肾动脉狭窄27例进行比较.结果介入组27例植入支架40枚,手术成功24例(88.9%,24/27),失败3例(11.1%,3/27),手术并发症5例(18.5%,5/27).术后在血压下降(包括收缩压舒张压)肌酐下降,肾小球滤过率增加方面,介入组获益率明显优于药物组,两组比较差异均有显著性,术后随访6个月~8年6个月,中位数为1年9个月,介入组有19例能比较健康的生活和工作,药物组仅12例能维持生活和工作.结论支架介入治疗较单纯药物治疗肾动脉狭窄疗效显著.  相似文献   
44.
Pulmonary thromboembolism is the leading direct cause of maternal deaths in the UK. The majority of deaths occur in the puerperium. Caesarean section has been recognised as a risk factor but there is concern that more attention to thromboprophylaxis after vaginal births is needed. The hospital maternity unit in Dumfries has written guidelines on thromboprophylaxis after vaginal births. This audit assessed the compliance with these guidelines within this maternity unit. The case notes relating to spontaneous vaginal births over a 2-month period (n=148) and instrumental vaginal births over a 7-month period (n=29) were reviewed. Information concerning venous thromboembolism risk and any thromboprophylaxis given was extracted. The audit showed that 9% of spontaneous vaginal births and 62% of instrumental vaginal births required specific thromboprophylaxis. However, only 31% of the spontaneous vaginal births and 22% of the instrumental vaginal births in which thromboprophylaxis was indicated did indeed receive the required treatment. Failure to respond to venous thromboembolism risk factors was common. Measures to increase the awareness of maternity staff to these factors are suggested.  相似文献   
45.
This review tries to summarize the efforts over the past 20 years to construct a tissue-engineered trachea. After illustrating the main technical bottlenecks faced nowadays, we discuss what might be the solutions to these bottlenecks. You may find out why the focus in this research field shifts dramatically from the construction of a tubular cartilage tissue to reepithelialization and revascularization of the prosthesis. In the end we propose a novel concept of 'in vivo bioreactor', defined as the design of a perfusion system inside the scaffold, and explain its potential application in the construction of a tissue-engineered trachea.  相似文献   
46.
目的 :探讨系统性红斑狼疮 (SLE)女性患者血清肿瘤标志物CA12 5 ,CA199含量变化及临床意义。方法 :用化学发光法测定 30例正常女性和 38例SLE女性患者血清中CA12 5 ,CA199含量。结果 :正常组CA12 5含量为 11.14± 6 .4 8U/ml,CA199含量为 3.75± 2 .89U/ml;SLE组CA12 5 ,CA199分别为 2 2 .5 6± 2 0 .4 6U/ml,9.5 7± 9.34U/ml。SLE患者CA12 5 ,CA199阳性率分别为 2 1.1% ,7.89%。结论 :SLE患者血清CAl2 5 ,CA199含量较正常组增高 (P <0 .0 5 )。CA12 5 ,CA199在SLE女性患者中可出现阳性 ,对临床诊断SLE有一定价值。  相似文献   
47.
等密度硬膜下血肿的CT诊断(附47例分析)   总被引:1,自引:0,他引:1  
本文分析了47例等密度硬膜下血肿的CT表现,观测的各种CT征象,发现(1)bolus增强扫描显示的血肿、血肿膜及表面移位血管;(2)中线结构的特征性偏移;(3)表面脑回聚拢内移;(4)脑灰白质界面内移;(5)侧脑室变形和脑—脑室指数变小,对等密度硬膜下血肿的诊断和鉴别诊断有重要意义。  相似文献   
48.
D. Koh    C. L. Goh    H. T. W. Tan    S. K. Nge  W. K. Wong 《Contact dermatitis》1997,37(1):32-34
This study attempts to demonstrate the existence of allergic contact dermatitis from grass, and to develop a patch test series to screen patients with grass intolerance. 6 common grass species from lawns and military training areas were collected. Solvent extracts of polar. non-polar and volatile fractions were prepared and used for patch testing in 20 control subjects and 46 patients with a history of grass intolerance. The 20 control had negative responses to patch testing. 5 out of 46 patients had positive patch tests to Axonopus compressus (carpet grass). Ischaenmum muticum (sea-shore centipede grass). Imperata evlindrica (lalang). Panicum maximum (Guinea grass) and Pennisetum purpureum (elephant grass). Reactions to the non-polar fraction for all 5 species were noted. This study demonstrates the existence of allergic contact dermatitis from various common species of grass. In our series, this is seen in 11% of those with a history of grass intolerance.  相似文献   
49.
Jugular foramen neuromas: a review of 14 cases   总被引:7,自引:0,他引:7  
We present 14 patients with jugular foramen neuromas treated in the professorial unit at the National Hospital, Queen Square, in the 20-year period from 1969 to 1989. The growth characteristics and associated symptomatology of these tumors are variable, and often they do not give rise to a typical jugular foramen syndrome, making differentiation from other low cerebellopontine angle tumors difficult and occasionally impossible. One tumor presented mainly in the neck, but the remaining 13 were predominantly intracranial and their anatomical relationships as defined radiologically determined the surgical approach used. Nine tumors were resected using a posterior fossa approach, three required a combined posterior fossa and neck dissection, and one a combined supratentorial and infratentorial craniotomy. The aim of operation was total excision of the tumor, which was achieved in 10 patients; the remaining three all suffered recurrence. There was no operative mortality and little long-term disability.  相似文献   
50.
Aim: Our aim was to compare the outcome in subsequent frozen embryo replacement cycles in four groups of patients who had elective cryopreservation of all their embryos because they were considered to be at increased risk of developing severe ovarian hyperstimulation syndrome. Design: Sixty-two (91%) of 68 IVF cycles (68 patients) in which elective cryopreservation of all embryos was performed were analyzed. All patients continued on the GnRH agonist, buserelin, after oocyte recovery until the onset of vaginal bleeding. Frozen embryo replacement occurred in a hormone replacement cycle that started either on day 3 of the withdrawal bleed (group I;N=15) or after serum estradiol levels had fallen to <100 pmol/L (group II;N=16). The other patients commenced a frozen embryo replacement cycle several months later in either a hormone replacement (group III;N=15) or a natural (group IV;N=16) cycle. Results: Two patients developed severe ovarian hyperstimulation syndrome. There were no significant differences among the four groups regarding demographic variables, the dose of hMG used, and the clinical outcome. There was a higher but not significantly different clinical pregnancy rate in group I (26.7%), compared to group II (12.5%), group III (13.3%), and group IV (18.8%). Conclusions: Several options exist for the timing and protocol used for frozen embryo replacement in patients who had elective cryopreservation for the prevention of ovarian hyperstimulation syndrome, none of which was found to be clearly superior in this observational report.Presented at the 1994 Annual Conference of the American Fertility Society.  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