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   35946篇
  免费   3096篇
  国内免费   1876篇
耳鼻咽喉   579篇
儿科学   510篇
妇产科学   819篇
基础医学   4200篇
口腔科学   569篇
临床医学   4228篇
内科学   6254篇
皮肤病学   816篇
神经病学   1927篇
特种医学   1220篇
外国民族医学   17篇
外科学   3626篇
综合类   4393篇
现状与发展   4篇
一般理论   7篇
预防医学   2377篇
眼科学   798篇
药学   3676篇
  23篇
中国医学   1693篇
肿瘤学   3182篇
  2024年   83篇
  2023年   491篇
  2022年   1156篇
  2021年   1534篇
  2020年   1120篇
  2019年   1163篇
  2018年   1290篇
  2017年   1103篇
  2016年   1049篇
  2015年   1560篇
  2014年   1923篇
  2013年   1914篇
  2012年   2693篇
  2011年   2846篇
  2010年   1836篇
  2009年   1362篇
  2008年   1963篇
  2007年   1865篇
  2006年   1891篇
  2005年   1853篇
  2004年   1343篇
  2003年   1277篇
  2002年   1098篇
  2001年   901篇
  2000年   826篇
  1999年   749篇
  1998年   458篇
  1997年   413篇
  1996年   334篇
  1995年   306篇
  1994年   275篇
  1993年   197篇
  1992年   327篇
  1991年   284篇
  1990年   218篇
  1989年   171篇
  1988年   192篇
  1987年   158篇
  1986年   123篇
  1985年   117篇
  1984年   84篇
  1983年   44篇
  1982年   25篇
  1981年   35篇
  1980年   21篇
  1979年   32篇
  1978年   24篇
  1977年   19篇
  1975年   18篇
  1973年   24篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
本文对20例20~36周引产死胎胸腺进行了解剖学,组织学观察,并应用吻合血管胎儿胸腺移植治疗晚期恶性原发及继发骨肿瘤12例。结果表明,胎儿胸腺的血供主要来自胸廓内动脉,其次为甲状腺下动脉和心包膈动脉胸腺支,7~8个月胎儿胸腺静脉血管壁较厚,适合作血管吻合,胸腺细胞发育成熟,组织结构正常,已有分泌胸腺素及转化免疫细胞的功能,在解剖学,组织学,免疫学方面均具备了良好的移植条件。12例接受吻合血管胎儿胸腺移植的晚期恶性骨肿瘤患者,其临床症状、体征、X线、免疫指数均有明显改善,患者生存6个月至37个月以上。  相似文献   
112.
The distribution of haloperidol-sensitive (+)[3H]N-allylnormetazocine ((+)[3H]SKF-10,047) binding sites (sigma sites) in subcellular fractions of rat brain homogenates was extensively characterized. In synaptosomal fractions, enriched in choline acetyltransferase activity, sigma sites were present in lower concentrations than in whole brain homogenates. On the other hand, microsomal and myelin fractions were found to be enriched in sigma sites. A similar pattern of enrichment was seen for 5'-nucleotidase activity, a general plasma membrane marker. However, subsequent experiments in which microsomes were subfractionated on linear sucrose gradients led to the recovery of sigma sites over a significantly lower density range than 5'-nucleotidase activity or ATP-stimulated [3H]ouabain binding, an additional plasma membrane marker. In addition, previously reported distributions of a number of other subcellular markers, including those for endoplasmic reticulum, were found to contrast with the observed distribution of sigma sites. It is concluded that rat brain sigma sites are not concentrated at synaptic regions of plasma membrane. However, the possibility that sigma sites are localized to specialized areas of nonsynaptic plasma membrane cannot be excluded.  相似文献   
113.
OBJECTIVE: To observe the changes of C-reactive protein (CRP) level and its relationship with blood lipids, and the effects of fluvastatin on CRP and the lipids in patients with hyperlipidemia. METHODS: Serum levels of cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein cholesterol (VLDL-C) and lipoprotein(a)[Lp(a)] were measured by enzyme assay, and plasma CRP level by immunonephelometry before and after fluvastatin treatment (20 mg/d for 4 weeks) in patients with hyperlipidemia. RESULTS: CRP levels were above normal in 90.3% hyperlipidemia cases in spite of the various accompanying diseases. Fluvastatin treatment significantly reduced TC (-7.49%), TG (-14.32%), LDL (-13.88%), VLDL (-18.48%) and TC/HDL(-13.50%) levels (P<0.01), and also brought down Lp(a) concentration (-13.81%). CRP levels was very effectively reduced after the treatment (-15.92%, P<0.001). No association between basal CRP levels and basal lipids and Lp(a) concentrations was observed. Positive correlation of CRP, however, was observed after fluvastatin treatment with TC/HDL (r=0.62, P=0.041) and Lp(a) (r=0.320, P=0.011), while inverse relations were noted between CRP and HDL (r=-0.288, P=0.023). CONCLUSION: CRP levels increases markedly in patients with hyperlipidemia, a fact that is independent of the accompanying diseases. In addition to modulating blood lipid levels, fluvastatin also reduces CRP level, the latter possibly serving as an independent predictive factor for atherosclerotic cardiovascular diseases and also as an indicator for estimating the effectiveness of the treatment.  相似文献   
114.
115.
目的探讨肛管癌诊断、治疗和预后的相关因素。方法北京医院1984-1998年间收治15例肛管鳞癌,首次诊断为肛管癌者仅5例。15例中行放疗化疗11例,8例行Miles手术。结果病理均证实为鳞癌。根据NCCN(2003年)分期,Ⅰ期6例,Ⅱ期4例,ⅢA期2例,ⅢB期3例。免疫组织化学染色显示肿瘤组织间质纤维化(+++)者4例,(++)者7例,(+)者4例。随诊最长10年,平均生存期(47±27.6)个月。结论肛门指诊是发现和诊断肛管癌的重要手段。放疗以及以放疗为主,化疗、手术为辅的综合治疗是肛管癌的主要治疗方法。肿瘤分期、腹股沟淋巴结转移、治疗方法以及肿瘤组织间质纤维化对病人的预后均有影响。  相似文献   
116.
冰点下降法测定血、尿渗透压的临床应用及注意事项   总被引:1,自引:0,他引:1  
本文应用溶液冰点下降法测定了178例正常血清渗透压。结果为287±13毫渗量/kg水。并对20例尿崩症病人在限水加压素试验过程中测定血清,尿渗透压。尿崩症病人尿渗透压明显低于正常人。注射加压素后,尿渗透压升到正常。在多尿症的鉴别诊断中,此法是一种简便,灵敏的手段。有重要的诊断价值。  相似文献   
117.
高血压鼠局部脑梗塞后脑超微结构改变动态观察   总被引:3,自引:0,他引:3  
本文选用肾血管性高血压鼠(RHR)复制大脑中动脉闭塞(MCAO)模型,其后2h至7d分8次取不同区域脑组织进行透射电镜动态观察超微结构的改变。显示局部脑梗塞后发生全脑性改变,其损害程度和出现时间梗塞区最早,以坏死为主,呈完全不可逆性损害;边缘区稍后,主要是微血管塌陷和微血栓形成及部分脑细胞坏死,呈部分可逆性损害,远隔区和镜区最迟,以内皮和星形细胞水肿为主,呈可逆性损害,认为用RHR复制MCAO,更接近于高血压性脑血管损害基础上发生脑梗塞的临床病理改变,全脑超微结构的动态性改变中微血管损害起着重要作用。  相似文献   
118.
三种去神经法对清醒大鼠动脉压力感受性反射功能的影响   总被引:3,自引:0,他引:3  
目的:测定急、慢性去主动脉神经(AD)、去颈动脉窦神经(SD)、同时去主动脉和窦神经(SAD)后大鼠动脉压力感受性反射对血压控制(ABR-BP)和心动周期控制(ABR-HP)的影响。方法:测定ABR-BP采用阻断动脉压力感受性反射传出通路前后,比较机体对去氧肾上腺素升压反应面积差异的方法,所得数值与改良的Smyth方法测定的ABR-HP值进行比较。结果:(1)大鼠SAD后ABR-HP为零,且代偿不明显;而ABR-BP约为30%,且代偿明显;(2)SD后ABR-BP与ABR-HP无显著差异,而AD和SAD后ABR-BP的作用显著大于ABR-HP的作用。结论:(1)大鼠的ABR-HP传入冲动全部来自于主动脉弓和颈动脉窦的压力感受器,而ABR-BP传入冲动大部分来自于这两处的感受器;(2)主动脉神经和窦神经感受传入在ABR-BP中的作用是相当的,并有明显的相互代偿;而在ABR-HP中,主动脉神经的作用比窦神经重要,其代偿能力也比窦神经显著。  相似文献   
119.
Histoclinical basis for a new classification of hemorrhoidal disease   总被引:3,自引:1,他引:2  
The present classification of first, second, and third grade hemorrhoids only reflects variation in size of a normal human tissue and does not relate to "hemorrhoidal disease." Cross-sections and coronal sections of the anal canal in 32 fetuses, with ages ranging from 28 to 38 weeks of development, were studied and the following fundamental facts were found: in the lumen of the anal canals of fetuses, there are prominences of mucosa formed by conjunctive and muscular tissue, arterial and venous vessels and glands, arranged without following any particular pattern, which resemble similar formations found in the adult that protrude equally in the inside of the canal, known as hemorrhoids. The muscular tissue, smooth or striated, is grouped in bundles, and bunches of collagen fibers of homogeneous, nonfragmented, and regular aspect are found between them. Blood vessels have an ample lumen with a defined structure of collagen tissue as well as muscular tissue in its walls. Prominences of mucosa are connected to the remainder of the intestinal wall by defined conjunctive thick, nonfragmented fibers, that permit firm adherence. In healthy adults, the findings were similar but there was an evident degenerative process in the collagen fibers. In 100 surgical specimens of hemorrhoidectomies, the histologic investigation demonstrated a severe inflammatory reaction that especially affected the blood vessel wall and conjunctive tissue, which probably produced an ischemic lesion of the mucosa that could condition the onset of a vascular thrombosis, allowing displacement of the mucosa and its protrusion through the anus. The files of 815 patients suffering from hemorrhoidal disease were also studied. The main physical findings were bleeding, thrombosis of the internal hemorrhoidal plexus, prolapse of the anal cushions, or a combination of these. The authors propose to classify hemorrhoidal disease as bleeding, prolapsing, thrombotic, and mixed hemorrhoidal disease, aiming toward a rational treatment.  相似文献   
120.
本文通过透射电镜观察水泡绦虫成虫体壁的结构,发现成虫体壁密布微毛并具纤毛,微毛顶端棘突系条状结晶蛋白。皮层基质区有许多液泡,内含颗粒或脂滴及不定形的基质。皮下层为有核细胞区,富有细胞器,实质中有较多电子致密细胞和核周体,并向皮层发出大小不等的胞质通道,构成一个片层状的管网结构,显示体壁能取代肠管的特殊功能。  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