首页 | 官方网站   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   48721篇
  免费   4128篇
  国内免费   1119篇
医药卫生   53968篇
  2024年   197篇
  2023年   847篇
  2022年   1617篇
  2021年   2283篇
  2020年   2357篇
  2019年   1589篇
  2018年   1568篇
  2017年   1878篇
  2016年   2064篇
  2015年   1625篇
  2014年   4383篇
  2013年   3519篇
  2012年   3951篇
  2011年   3997篇
  2010年   3149篇
  2009年   2223篇
  2008年   2105篇
  2007年   2153篇
  2006年   1810篇
  2005年   1564篇
  2004年   1218篇
  2003年   1237篇
  2002年   879篇
  2001年   844篇
  2000年   726篇
  1999年   516篇
  1998年   428篇
  1997年   391篇
  1996年   328篇
  1995年   346篇
  1994年   327篇
  1993年   266篇
  1992年   232篇
  1991年   175篇
  1990年   147篇
  1989年   104篇
  1988年   78篇
  1987年   76篇
  1986年   58篇
  1985年   118篇
  1984年   98篇
  1983年   86篇
  1982年   86篇
  1981年   56篇
  1980年   74篇
  1979年   31篇
  1978年   47篇
  1977年   24篇
  1976年   23篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
A prototype electronic radial scan ultrasound endoscope has been developed by Olympus (Tokyo, Japan) for endoscopic ultrasound (EUS) study. The ultrasound view‐angle of this model is 360° vertical to the scope. Though the diameter of the scanner and the shaft of the scope is bigger than those of the present mechanical radial scan model, clinical manipulation of the new scope is the same as that of the present model. Image quality of the ultrasound picture demonstrated by the electronic radial model was as clear as those provided by the mechanical radial scan model. Ultrasound penetration was better and satisfactory because of less echoic reduction compared to the mechanical radial model. The newly developed electronic radial model can be evaluated as an ultrasound endoscope for the next generation. The advantage of this system is to facilitate the clinical use of color Doppler function and tissue harmonic imaging, and this system can be operated by the same monitor unit as a convex model of ultrasound endoscope.  相似文献   
72.
作者应用免疫细胞化学法研究了HFRS尸检内分泌及其有关组织中病毒抗原的分布,病毒抗原阳性细胞与病变的关系,病变的类型及病毒感染对胰腺内胰岛素表达的影响,所用的一抗有抗肾综合征出血热(HFRS)病毒糖蛋白(G_2),核蛋白(NP)及血凝素(HA)抗原的单克隆抗体(15种)和多克隆抗体(PAb)以及抗胰岛素(INS)单克隆抗体。结果显示,内分泌组织中有两种染色形态的病毒抗原,一种是胞浆弥漫染色的抗原,为G_2,NP或HA阳性,阳性细胞弥漫分布,另一种是以病毒包涵体(IB)形式出现的颗粒性抗原,MAbs染色多为实性,PAb染色多为空泡状。在9例胰腺组织中,有4例几乎在所有腺上皮细胞和少数胰岛细胞均为IB阳性,但PAb染色可在胰岛细胞中显示出空泡状IB。在其它内分泌组织中,IB只在少数细胞中出现。抗原阳性细胞很少出现坏死,但在脑垂体及肾上腺灶性或片状凝固性坏死区域也有弥漫性抗原阳性及IB存在。胰腺组织的胰岛素染色显示,除1例胰岛INS强阳性,其余8例均有明显的INS染色减弱及阳性细胞减少的表现。结果提示,内分泌组织中有两种病变,即以IB为特征的病毒直接感染引起的细胞病变,是病毒的弱致病变作用,该病变可能对细胞的内分泌功能产生影响;另一种病变是组织的灶性或大片性同步性凝固性坏死,是继发于病毒感染后的出血和休克,该病变会  相似文献   
73.
This paper considers a pole assignment problem to cluster all poles of a closed-loop system into some specified regions by introducing the complex state for systems having an isotropic property and by using the Riccati equation. The algebraic relations for the distribution of the eigenvalues of a complex matrix are used in order to cluster the poles into specified regions, which guarantees the relative stability margin, e.g. uniform damping or uniform damping ratio. The proposed scheme is essentially a combination of the pole assignment approach and linear quadratic design, taking the advantages of both. A block modal control method—an extension of recursive pole assignment—is also developed for the vibration control of rotating systems by clustering the forward and backward modes in order. Vibration control simulations with an isotropic rotor—bearing system, a magnetic bearing system and a rotating circular disc are treated in order to demonstrate the advantages of the proposed method.  相似文献   
74.
复方山绿茶缓释袋泡剂的研究   总被引:6,自引:0,他引:6  
董泽民 《中成药》1993,15(12):7-9
用网状多孔性纤维包念材料制备的复方山绿茶缓袋泡剂,具有速释和缓释作用,在1-8h内按埝级方式释药。T0.5为1.3h,Td为3.2h,1-8h的平均释药速率72.35mg/h。与传统的半生药型袋泡剂比较,具有栽药量高,使用方便,性质稳定,疗效确切的优点。  相似文献   
75.
A 60-year-old Japanese man was hospitalized because of urinary leakage from the anus on October 3, 1994. Retrograde urethrography detected a fistula between the bulbous urethra and the rectum. Urethrocystoscopy revealed a tumor on the urethrorectal fistula. Tumor biopsy showed a well differentiated adenocarcinoma. Cystourethrectomy with fistulectomy, and ileal conduit urinary diversion were performed. Pathological examination revealed primary adenocarcinoma in the fistula with invasion to the prostatic urethra and bladder wall. The patient showed no evidence of a recurrence as of August, 1996.  相似文献   
76.
目的:探讨不同供者来源脐血混合移植的可行性和植入特性。方法:分别将两份人HLA半相合混合脐血或单份脐血输入经亚致量照射后的严重联合免疫缺陷(SCID)小鼠,观察两组脐血在SCID小鼠体内的植入状况及多系造血重建特性。结果:混合脐血和单份脐血移植均可在受鼠体内植入,形成供-受混合嵌合体,并能重建多系造血,存活率和植入率无统计学意义(P>0.05)。用多聚酶链反应-序列特异性寡核苷酸(PCR-SSO)探针检测人HLA-DQB1基因发现,HLA半相合混合脐血移植可有1份或2份脐血植入,其中造血祖细胞含量和体外克隆形成能力高者,更易于植入,造血重建特性与单一脐血移植比较无统计学意义。结论:HLA半相合人混合脐血可同时在SCID小鼠体内植入,形成来自供-受三者的多嵌合状态,并能重建造血及免疫功能。  相似文献   
77.
A study of C4 bound to human erythrocytes in vitro and in vivo has been made by immunoblotting with mouse monoclonal anti-C4c and anti-C4d and human polyclonal anti-C4d (Rodgers and Chido) following SDS-PAGE. Multi-banded patterns differentiated between C4A and C4B isotypes. Treatment of EC4b with trypsin eliminated immunoblotting but not agglutination reactions. Serum inactivation (factor I) of EC4b resulted in banding patterns similar to those obtained from patients' EC4d. Treatment of EC4b membranes with NH2OH affected many of the bands, two were lost, one was markedly reduced and others had altered SDS-PAGE mobility. Interpretation of the bands has been made in terms of C4-acceptor complexes and inactivation fragments of C4. A distinct difference in the banding of C4A and C4B isotypes has been detected.  相似文献   
78.
We describe a patient with probable dementia with Lewy bodies (DLB) whose Parkinsonism worsened after administration of rivastigmine within the therapeutic dose range. Some extrapyramidal signs (EPS) then reversed to pre-treatment level after rivastigmine dose reduction. We draw attention to the need of EPS monitoring during titration of cholinesterase inhibitors in patients with DLB. This is the first report to our knowledge of iatrogenic worsening of Parkinsonism which was successfully managed by dose reduction.
Sommario Si descrive il caso di un paziente affetto da Demenza a corpi di Lewy (Dementia with Lewy Bodies, DLB) probabile, in cui si è assistito ad un peggioramento del parkinsonismo dopo somministrazione di rivastigmina a dosi terapeutiche. Alcuni segni extrapiramidali sono regrediti al livello pre-trattamento con una riduzione posologica di rivastigmina. Si sottolinea la necessità di un monitoraggio dei segni extrapiramidali durante la titolazione della terapia con inibitori dell’acetilcolinesterasi cerebrale in pazienti con DLB. Questo è il primo caso descritto, a nostra conoscenza, di un peggioramento iatrogeno di parkinsonismo efficacemente gestito con una riduzione posologica della terapia con rivastigmina.
  相似文献   
79.
FE复合酶防治烧伤后期肉芽创面感染的临床观察   总被引:2,自引:1,他引:1  
目的观察FE复合酶控制烧伤后期肉芽创面常见耐药菌感染的作用。方法选取笔者单位烧伤患者30例,随机分为治疗组15例,将FE复合酶50 ml溶于等渗盐水0-150 ml中,使其终浓度为1-3 U/ml,用无菌纱布浸湿该液后湿敷创面,1-2次/d;对照组15例,用庆大霉素+ 等渗盐水纱布湿敷创面,1-2次/d。于用药前及用药后1-5 d取创面分泌物作细菌培养,检测两组患者创面的细菌种类及所用药物对创面细菌的敏感率;观察两组患者创面愈合时间及植皮术后3、5、 8、10、12 d的创面愈合率。结果两组患者创面细菌以铜绿假单胞菌、大肠杆菌、阴沟肠杆菌、甲氧西林耐药金黄色葡萄球菌(MRSA)为主。治疗组对MRSA、表皮葡萄球菌、腐生葡萄球菌、铜绿假单胞菌、大肠杆菌、阴沟肠杆菌的敏感率分别为93.8%、100.0%、100.0%、100.0%、100.O%、95.0%,高于对照组的17.6%、31.3%、28.6%、44.0%、33.3%、28.0%(P<0.01)。治疗组植皮术后创面愈合时间为(10.6±1.5)d,明显短于对照组[(15.3±1.7)d,P<0.01]。治疗组患者植皮术后各时相点创面愈合率均明显高于对照组(P<0.01),植皮术后10 d治疗组创面愈合率为(85.4±2.4)%,与对照组(51.3±1.5)%比较,差异有统计学意义(P<0.01)。结论 FE复合酶可以有效控制创面感染,提高烧伤后期感染创面植皮成功率。  相似文献   
80.
从脾论治磺脲类降糖药继发性失效   总被引:2,自引:0,他引:2  
对 64例 2型糖尿病继发磺脲类降糖药失效患者 ,在继续口服磺脲类药的基础上加用健脾中药 ,结果显效 1 5例 ,有效 3 6例 ,无效 1 3例 ,总有效率 85 .2 4% ;治疗前后血糖明显下降 ,有显著性差异 ( P<0 .0 0 1 )  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-23

京公网安备 11010802026262号