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   4141篇
  免费   336篇
  国内免费   12篇
耳鼻咽喉   126篇
儿科学   143篇
妇产科学   230篇
基础医学   581篇
口腔科学   87篇
临床医学   490篇
内科学   812篇
皮肤病学   29篇
神经病学   402篇
特种医学   173篇
外国民族医学   1篇
外科学   484篇
综合类   58篇
一般理论   1篇
预防医学   322篇
眼科学   56篇
药学   257篇
中国医学   2篇
肿瘤学   235篇
  2023年   19篇
  2022年   25篇
  2021年   69篇
  2020年   31篇
  2019年   55篇
  2018年   84篇
  2017年   45篇
  2016年   54篇
  2015年   59篇
  2014年   102篇
  2013年   146篇
  2012年   202篇
  2011年   222篇
  2010年   115篇
  2009年   132篇
  2008年   187篇
  2007年   199篇
  2006年   221篇
  2005年   182篇
  2004年   162篇
  2003年   150篇
  2002年   150篇
  2001年   138篇
  2000年   118篇
  1999年   101篇
  1998年   59篇
  1997年   72篇
  1996年   88篇
  1995年   69篇
  1994年   53篇
  1993年   43篇
  1992年   103篇
  1991年   74篇
  1990年   60篇
  1989年   76篇
  1988年   63篇
  1987年   90篇
  1986年   66篇
  1985年   69篇
  1984年   75篇
  1983年   44篇
  1982年   26篇
  1981年   36篇
  1980年   33篇
  1979年   47篇
  1978年   30篇
  1977年   39篇
  1975年   21篇
  1974年   28篇
  1973年   21篇
排序方式: 共有4489条查询结果,搜索用时 31 毫秒
81.
Restoration of bone stock in revision surgery of the femur   总被引:3,自引:0,他引:3  
Three hundred and four femoral revisions were performed from 1987 to the end of 1990. All were done with cementless titanium calcar replacement prostheses, designed for proximal bone loading. Type III bone deficiencies were present in 160 femurs, all requiring supplemental cortical bone plates for bony augmentation. All grafts united and provided increased bone stock in the long term. Physiologic loading is important for graft remodeling and maturation. Hip scores have improved from an average Harris Hip Score of 44 to 84. Current survivorship at 10 years is 96%, and the revision rate is 3.2%. Thigh pain is mild in 3% of cases. There have been no late failures or distal lysis noted to date.
Résumé  De 1987 à 1990, on a procédéà 304 reprises de prothèse totale de hanche (PTH) associées à des implants fémoraux standard en alliage de titane non cimentés et spécifiquement étudié et réalisés pour bien s’adapter à la morphologie osseuse et à la résistance mécanique proximale. 160 cas de fémur nécessitèrent – vu la présence de perte de sustance osseuse de type III – la mise en place sur la corticale de plaque osseuse de remplacement afin d’augmenter et la repousse fémorale osseuse. On observe dans les cas de reprise de PTH, une amélioraton du recul moyen: ce dernier passait de 44 mois (selon l’échelle de le Harris Hip score) à 84 mois. A l’heure actuelle, le taux actuariel de survie des implant est de 96% à 10 ans avec un taux de reprise de 3.2%. On note la presence de douleur à la cuisse dans 3% des cas, mais à l’heure actuelle, on ne rapporte aucun échec tardif ni osteolyse distale.


Accepted: 7 December 1999  相似文献   
82.
目的 研究颈分区性清扫术在头颈部鳞状细胞癌 (简称鳞癌 )治疗中的效果。方法 回顾性分析 1997年 1月~ 2 0 0 1年 12月在中国医学科学院肿瘤医院接受分区性清扫术的头颈部鳞癌患者 12 3例 ,其中喉癌 77例、口腔癌 2 9例、口咽癌 2例、下咽癌 15例。分区性清扫术后发现淋巴结病理阴性 (pN0 ) 99例 ,淋巴结病理阳性 (pN + ) 2 4例。随访时间中位数为 2 5个月。结果  10 1例cN0患者行分区性清扫术后发现pN + 14例 ( 13 9% ) ;2 2例cN +患者行分区性清扫术后发现pN + 10例( 4 5 5 % )。 15 7侧分区性清扫标本中共发现 5 2枚阳性淋巴结 ,其在颈部的分布如下 :Ⅰ区 2 5 % ,Ⅱ区4 8% ,Ⅲ区 2 5 % ,Ⅳ区 2 %。根据Kaplan Meier方法计算 5年颈部复发率 ,pN0患者为 5 87% ( 95 %可信区间 0 8% ,10 9% ) ,pN +患者为 9 2 % ( 95 %可信区间 0 0 % ,2 1 5 % )。结论 颈分区性清扫术从微创观念出发 ,只要选择恰当 ,对于头颈部鳞癌患者可以取得与传统颈清扫术相当的效果。更重要的是保留了患者的功能和外观 ,提高了生活质量  相似文献   
83.
目的 观察重度阻塞性睡眠呼吸暂停低通气综合征 (obstructivesleepapneahypopneasyndrome ,OSAHS)围手术期病情变化和持续正压通气治疗 (continuouspositiveairwaypressure,CPAP)的影响 ,探讨围手术期治疗的必要性。方法  45例重度OSAHS患者均接受了完整保留悬雍垂的改良悬雍垂腭咽成形术。其中 2 4例不做围手术期CPAP治疗的作对照组 ,2 1例行围手术期CPAP治疗 :术前CPAP治疗 7d以上 ,于术后 1~ 3d夜应用自动调节治疗压力的CPAP(autotitratedCPAP ,AutoSet)进行治疗。治疗组患者术后第二夜在AutoSet治疗下同时做多导睡眠监测 (polysomnography,PSG)。对呼吸暂停低通气指数 (apneahyponeaindex ,AHI)、最低血氧饱和度 (lowestSaO2 ,LSaO2 )、血压以及睡眠结构等指标进行观察。结果 对照组 2 4例患者中有 6例于术后第二夜LSaO2 比术前下降 ,AHI升高 ,另外 1 8例患者LSaO2 升高 ,AHI下降。治疗组 2 1例患者CPAP治疗前AHI为 (61 1± 9 9)次 /h( x±s,以下同 ) ,LSaO2 为 65 0 %± 9 6 % ,手术前CPAP治疗后AHI为 (2 2± 1 4)次 /h ,LSaO2 为 94 5 %± 2 9% ,t检验P <0 0 0 1 ;手术前经CPAP治疗临床症状消失。术后患者均能良好耐受AutoSet治疗 ,术后第二夜应用AutoSet治疗时AHI为 (3 6± 1 8)次 /h  相似文献   
84.
目的 探讨颈总动脉切除术的适应症和术前准备的一般规律。方法 对我院自1986年~2003年17年问的10例颈总动脉切除术病例进行回顾性分析。其中年龄22~59岁,急诊手术4例,选择性颈动脉切除6例。结果 急诊手术中2例出现中枢神经系统并发症,选择性手术组中1例出现中枢神经系统并发症。除1例因脑转移癌死亡外,随访均健在。结论 行不重建血管的颈总动脉及分歧部切除术,高龄患者须严格掌握适应症,须无脑血管疾病史,术前须进行Matas试验,要有侧支循环建立的客观依据;对年轻患者(30岁以下)可适当放宽手术指征。  相似文献   
85.
不同术前放射治疗剂量在下咽鳞癌综合治疗中的意义   总被引:4,自引:0,他引:4  
目的 探讨下咽鳞癌不同术前放射治疗剂量对综合治疗的影响。方法 回顾性分析2 0 1例 (男 181例 ,女 2 0例 ;年龄 32~ 75岁 )经术前放射治疗 手术综合治疗 (R S)的下咽鳞癌 (1997年UICC分期Ⅰ期 6例 ,Ⅱ期 14例 ,Ⅲ期 4 7例 ,Ⅳ期 134例 ) ,其中梨状窝 173例 ,咽后壁 19例 ,环后 9例。 12 4例术前放射治疗 4 0Gy ,77例术前放射治疗 5 0Gy ;放射治疗后 2周左右给予手术治疗。结果 术前放射治疗 4 0Gy组 5年生存率为 39.7% ,5 0Gy组为 5 5 .4 % (P <0 .0 5 )。术前放射治疗 4 0Gy组放射治疗相关性术后并发症发生率为 2 6 .6 % ,5 0Gy组为 15 .6 % (P <0 .0 5 )。术前放射治疗 4 0Gy组喉功能保留率为 38.7% ,5 0Gy组为 4 2 .9% (P >0 .0 5 )。术前放射治疗 4 0Gy组区域复发率为 2 8.2 % ,5 0Gy组为 2 9.9% (P >0 .0 5 )。结论 术前放射治疗 5 0Gy较 4 0Gy能提高下咽鳞癌的远期生存率 ,且不增加放射治疗引起的术后并发症 ,并有望增加喉功能的保留率。  相似文献   
86.
Objective To assess the effects of medroxyprogesterone acetate on bone density in women who have had a hysterectomy
Design Randomised, double-blind, placebo-controlled trial of medroxyprogesterone acetate 10 mg, 20 mg or placebo as an adjunct to oestrogen therapy.
Participants One hundred and twenty-three women, aged 18 to 45 years and currently receiving daily oestrogen, who presented at a university-based rheumatology practice.
Interventions The women were randomly assigned to receive either medroxyprogesterone acetate 10 mg, 20 mg or placebo daily beginning on day 15 of each month for one year. Forty-one women were randomised into each group.
Main outcome measure The primary outcome measurement was the percentage of change from baseline in bone mineral density of the lumbar spine (L2–L4). Secondary outcome measures included differences in femoral neck bone density, cholesterol and triglyceride levels between groups.
Results At one year, change in bone mineral density did not differ between either the treatment or placebo groups. Medroxyprogesterone acetate 20 mg and 10 mg led to statistically significant reductions in very low density lipoprotein cholesterol, total triglycerides, and very low density lipoprotein triglycerides when compared with placebo. Medroxyprogesterone acetate 20 mg also led to a statistically significant reduction in high density lipoprotein cholesterol, high density lipo-protein-2 cholesterol, and high density lipoprotein-2 triglycerides.
Conclusions Medroxyprogesterone acetate at either dose as an adjunct to oestrogen did not improve bone mineral density at one year when compared with placebo. Medroxyprogesterone acetate 10 mg may not adversely affect lipids. Medroxyprogesterone acetate 20 mg, however, did reduce high density lipoprotein cholestrol and therefore may increase cardiovascular risk.  相似文献   
87.
Objective To measure the gain in quality of life due to hormone replacement therapy for women with mild and severe menopausal symptoms.
Design Prospective study where data on quality of life and willingness to pay were collected by interview.
Setting Department of Gynaecology at Sodertalje Hospital near Stockholm.
Participants One hundred and four women aged 45 to 65 years treated for menopausal symptoms for at least one month.
Methods Quality oflife was measured by the time tradeoff and rating scale methods. The willingness to pay for hormone replacement therapy was investigated using the contingent valuation method.
Main outcome measures The quality adjusted life year weight measured with the rating scale and time tradeoff methods, and willingness to pay.
Results The increase in the quality adjusted life year weight due to hormone replacement therapy for women with mild symptoms was 0.26 according to the rating scale method and 0.18 according to the time tradeoff method. For women with severe symptoms the quality adjusted life year weight increased by 0.50 according to the rating scale method and by 0.42 according to the time tradeoff method. The mean willingness to pay for hormone replacement therapy per month was 2300 Swedish krone for women with mild symptoms and 4800 Swedish krone for women with severe symptoms (£1 = 10.3 Swedish krone).
Conclusions Hormone replacement therapy leads to a major improvement in quality of life for women with menopausal symptoms. Both for women with mild and severe menopausal symptoms the willingness to pay for the treatment also greatly exceeds the costs, indicating that hormone replacement therapy is economically beneficial for women with menopausal symptoms.  相似文献   
88.
In order to assess the reliability of intrauterine pressure measurements in the third stage of labour, catheter-tip transducers were used in 20 women randomly allocated into two groups of 10. In each case in the first group two catheters were tied together and introduced transcervically into the uterine cavity after delivery of the placenta. In each case in the second group two catheters were inserted independently into the same uterine cavity. The active and cumulative active pressures recorded from the pairs of catheters within each uterine cavity were compared. Comparison of individual active pressure readings from separate transducers revealed good agreement whether the catheters were tied together or were seperate. Cumulative active pressure was very similar when assessed by each catheter in the same uterus. Intrauterine catheter-tip transducers can be used reliably to measure uterine activity in the third stage of labour although there may be minor contraction by contraction differences in recordings of individual active pressures.  相似文献   
89.
PURPOSE: Prostate-specific membrane antigen (PSMA) is a cell surface protein that is overexpressed in prostate cancer, including hormone-refractory and metastatic disease. Our goal in this study was to develop a series of PSMA-based imaging agents for clinical use. EXPERIMENTAL DESIGN: We have synthesized and evaluated the in vivo biodistribution of two radiolabeled urea derivatives that have high affinity for PSMA in severe combined immunodeficient mice harboring MCF-7 (breast, PSMA-negative), PC-3 (prostate, PSMA-negative), and LNCaP (prostate, PSMA-positive) xenografts. Radiopharmaceutical binding selectivity and tumor uptake were also evaluated in vivo using dedicated small animal positron emission tomography, single photon emission computed tomography, and gamma scintigraphic imaging devices. N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-S-[(11)C]methyl-L-cysteine ([(11)C]DCMC K(i), 3.1 nmol/L) and N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-S-3-[(125)I]iodo-L-tyrosine ([(125)C]DCIT K(i), 1.5 nmol/L) were synthesized using [(11)C]CH(3)I and with [(125)I]NaI/Iodogen, respectively.RESULTS: At 30 minutes postinjection, [(11)C]DCMC and [(125)I]DCIT showed tumor/muscle ratios of 10.8 and 4.7, respectively, with clear delineation of LNCaP-derived tumors on imaging. MCF-7- and PC-3-derived tumors showed significantly less uptake of [(11)C]DCMC or [(125)I]DCIT. CONCLUSION: These results show the feasibility of imaging PSMA-positive prostate cancer using low molecular weight agents.  相似文献   
90.
Histone deacetylase inhibitors (HDIs) are a new class of drugs with significant antileukemic activity. To explore mechanisms of disease-specific HDI activity in acute myeloid leukaemia (AML), we have characterised expression of all 18 members of the histone deacetylase family in primary AML blasts and in four control cell types, namely CD34+ progenitors from umbilical cord, either quiescent or cycling (post-culture), cycling CD34+ progenitors from GCSF-stimulated adult donors and peripheral blood mononuclear cells. Only SIRT1 was consistently overexpressed (>2 fold) in AML samples compared with all controls, while HDAC6 was overexpressed relative to adult, but not neo-natal cells. HDAC5 and SIRT4 were consistently underexpressed. AML blasts and cell lines, exposed to HDIs in culture, showed both histone hyperacetylation and, unexpectedly, specific hypermethylation of H3 lysine 4. Such treatment also modulated the pattern of HDAC expression, with strong induction of HDAC11 in all myeloid cells tested and with all inhibitors (valproate, butyrate, TSA, SAHA), and lesser, more selective, induction of HDAC9 and SIRT4. The distinct pattern of HDAC expression in AML and its response to HDIs is of relevance to the development of HDI-based therapeutic strategies and may contribute to observed patterns of clinical response and development of drug resistance.  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