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   7545篇
  免费   406篇
  国内免费   167篇
耳鼻咽喉   83篇
儿科学   79篇
妇产科学   29篇
基础医学   810篇
口腔科学   204篇
临床医学   413篇
内科学   727篇
皮肤病学   41篇
神经病学   495篇
特种医学   137篇
外科学   519篇
综合类   1186篇
预防医学   440篇
眼科学   61篇
药学   2414篇
  3篇
中国医学   333篇
肿瘤学   144篇
  2023年   82篇
  2022年   129篇
  2021年   201篇
  2020年   160篇
  2019年   165篇
  2018年   191篇
  2017年   205篇
  2016年   209篇
  2015年   187篇
  2014年   465篇
  2013年   533篇
  2012年   495篇
  2011年   458篇
  2010年   380篇
  2009年   413篇
  2008年   328篇
  2007年   354篇
  2006年   319篇
  2005年   318篇
  2004年   259篇
  2003年   163篇
  2002年   166篇
  2001年   138篇
  2000年   129篇
  1999年   115篇
  1998年   99篇
  1997年   101篇
  1996年   74篇
  1995年   72篇
  1994年   88篇
  1993年   59篇
  1992年   85篇
  1991年   75篇
  1990年   74篇
  1989年   78篇
  1988年   59篇
  1987年   59篇
  1986年   55篇
  1985年   68篇
  1984年   53篇
  1983年   33篇
  1982年   50篇
  1981年   38篇
  1980年   36篇
  1979年   39篇
  1978年   24篇
  1977年   29篇
  1976年   31篇
  1974年   28篇
  1973年   40篇
排序方式: 共有8118条查询结果,搜索用时 46 毫秒
31.
海藻酸钠微球在部分性脾栓塞术中的应用评价   总被引:2,自引:0,他引:2  
目的 评价海藻酸钠微球(KMG)行部分性脾栓塞术(PSE)治疗肝癌并脾功能亢进(脾亢)的疗效及并发症。资料与方法 58例肝癌并脾亢行PSE患者,依据PSE术所采用的栓塞材料不同分为2组:A组30例,栓塞材料为明胶海绵颗粒;B组28例,栓塞材料为KMG。随访观察两组外周血自细胞(WBC)、血小板(PLT)和红细胞(RBC)计数变化及术后反应。结果 两组患者术后1周、2周、1个月、6个月的WBC和PLT计数均较术前明显升高(P〈0.001)。虽然B组术后WBC和PLT计数较A组升高较多,但两组的疗效差异无统计学意义(P〉0.05)。两组术后RBC计数一直无明显变化(P〉0.05)。随着栓塞程度的增加,外周血WBC和PLT计数升高越明显,但是术后反应加重.并发症也随之增加。结论 KMG可作为PSE术的栓塞材料,将栓塞程度控制在50%~60%可有效治疗脾亢,减轻术后反应。  相似文献   
32.
目的比较碳酸锂合并丙戊酸钠与单用碳酸锂对预防双相障碍复发的疗效。方法对82例临床康复的双相障碍患者随机分为碳酸锂合并丙戊酸钠组及单用碳酸锂组,合并用药组44例,单用碳酸锂组38例,随访观察2年。结果合并用药组有效率为88.6%,单用碳酸锂组有效率为68.4%,两组比较差异有显著性(P<0.05)。结论碳酸锂合并丙戊酸钠对双相障碍有较好的预防复发作用。  相似文献   
33.
目的 探讨不同浓度丁酸钠诱导对体外培养树突状细胞(DC)细胞表型的变化规律.方法 通过粒细胞-巨噬细胞集落刺激因子(rhGM-CSF)和白细胞介素-4(IL-4)体外诱导的人外周血单个核细胞来源的DC,按不同丁酸钠浓度和不同诱导时间分组培养,流式细胞仪检测各组DC的细胞表型.结果 在丁酸钠诱导下,各组DC表面的成熟标志均显著下调,丁酸钠浓度越高下调越明显,随着培养时间的延长,各组DC表面的成熟标志均显著下调;但是细胞的凋亡率也同时上升.结论 丁酸钠在体外可以显著抑制DC的成熟过程,以丁酸钠浓度为0.75mmol/L和培养48h为最佳的诱导浓度和时间.  相似文献   
34.
The differential effects of the pyrethroid tetramethrin on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) single sodium channel currents in rat dorsal root ganglion (DRG) neurons were investigated using the outside-out configuration of patch-clamp technique. Channel conductances were 10.7 and 6.3 pS for TTX-S and TTX-R sodium channels, respectively, at a room temperature of 24–26°C. The single-channel current of TTX-S sodium channels at the test potential of −30 mV was −1.27 ± 0.25 pA, and was not changed after exposure to 10 μM tetramethrin (−1.28 ± 0.23 pA). The open time histogram of TTX-S single-channel currents could be fitted by a single exponential function with a time constant of 1.27 ms. After exposure to 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 1.36 ms (τfast) and 5.73 ms (τlow). The percentage of contribution of each component to the population was 62% for the fast component representing the normal channels and 38% for the slow component representing the tetramethrin modified channels. The amplitudc of TTX-R single-channel currents was slightly changed from −0.72 ± 0.14 to −0.83 ± 0.07 pA by 10 μM tetramethrin. The open time histogram of TTX-R single-channel currents could be fitted by a single exponential function with a time constant of 1.92 ms. In the presence of 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 2.07 ms (τfast) and 9.75 ms (τslow). The percentage of contribution of each component was 15% for the fast, unmodified component and 85% for the slow, modified component. Differential effects of tetramethrin on the open time distribution of single sodium channel currents explains the differential sensitivity of TTX-S and TTX-R sodium channels.  相似文献   
35.
Summary The fractional clearance of lithium (CLLi/CLcr) calculated in 15 normal healthy adults from a single morning urine aliquot collection, together with a single venous blood sample (FQ) was compared with the average CLLI/CLCR obtained from three timed consecutive urine collections with mid-point blood sampling (FABC). Lithium had been ingested 15–18 h prior to the collection of these samples. Mean CLLi/CLCR was similar (FQ, 0.186, FABC, 0.177), with a highly significant correlation in each individual of CLLI/CLSR measured by either method (r = 0.97,P 0.0001). Proximal tubular reabsorption of sodium using lithium clearance may be calculated from a single urine and blood sample.  相似文献   
36.
The sodium intake of sodium deplete sheep was studied during local, push-pull perfusion of different solutions within the third cerebral ventricle. Sheep were made sodium deplete by continuous loss of parotid saliva, and were allowed access to 0.6 M NaHCO3 solution for 2 h daily. Local perfusion within the third cerebral ventricle was performed before and during the access to sodium solution. Four perfusion sites were used: anterior dorsal and ventral, and posterior dorsal and ventral. Perfusion of 200 mM Na-csf caused a decrease in sodium intake at each perfusion site. Perfusion of ouabain, 10−6M, caused a reduction in sodium intake only during perfusions within the anterior portion of the third ventricle. The results may indicate that specific neuronal elements sensitive to changes in intracellular sodium concentrations are located around the anterior portion of the third cerebral ventricle. These neurones, however, are not exclusive sites from where sodium intake of sodium deplete sheep can be influenced.  相似文献   
37.
Two experiments were performed to investigate the relationship between the expression of sodium appetite and the appearance of Fos-like immunoreactivity (Fos-IR) in the brain of rats. In the first experiment, rats were depleted of sodium by treatment with furosemide 24 h prior to sacrifice and without access to either food or sodium solution. Some rats had access to distilled water, and others had no fluids available during the 24 h. All of the furosemide-treated rats showed Fos-IR in both the subfornical organ (SFO) and around the organum vasculosum laminae terminalis (OVLT). Rats with access to distilled water during the depletion period showed no Fos-IR in the supraoptic (SON) or paraventricular hypothalamic nuclei (PVN) and, in parallel behavioral studies, comparably-treated rats consumed only 0.3 M NaCl solution at the end of the 24 h. In rats that had no fluids during the deprivation period, only about one half showed Fos-IR in SON and PVN and, in parallel behavioral studies, comparably treated rats consumed both water and 0.3 M NaCI solution at the end of 24 h. In a second experiment, cerebroventricular administration of renin stimulated short latency intake of 0.3 M NaCI and water. The relative intakes of water and NaCl were comparable at a low dose of renin, but intake of water exceeded that of NaCl after higher doses. Renin induced Fos-IR in SFO, MnPO, peri-OVLT region, SON and PVN. Both Fos-IR and fluid intake were antagonized by administration of losartan, an angiotensin 11 type 1 receptor antagonist. Thus, only the circumventricular organs of the lamina terminalis showed Fos-IR during each natriorexigenic regimen in these studies. These data support the view that Ang 11 of both central and peripheral origin activates the SFO and/or peri-OVLT region and contributes to sodium appetite.  相似文献   
38.
正常血钾型周期性麻痹SCN4A基因新突变的检测   总被引:7,自引:1,他引:6  
目的 报道正常血钾型周期性麻痹 (normoPP)一家系的临床特点 ,并筛查SCN4A基因以期发现有义突变。方法 提取知情同意的患者及部分家属外周血基因组DNA ,应用变性高效液相色谱分析 (DHPLC)技术筛查患者SCN4A基因全部 2 4个外显子 ,对发现异常者进行测序分析。结果先证者常规实验室检查未见异常 ,发作期肌酸激酶 (CK) 112 6U/L(正常值 <2 0 0U/L) ,肌电图正常。发作间期行肌肉活检未见显著异常。基因研究发现先证者及其父亲 (患者 )SCN4A基因发生同一新突变G2 10 1A ,并引起氨基酸序列改变Arg6 75Gln。该突变不同于目前发现的明确导致高钾型周期性麻痹(hyperPP)的突变 ,也不同于已知的SCN4A基因所有突变。结论 normoPP患者存在一新突变Arg6 75Gln ,该突变可能与疾病相关。  相似文献   
39.
目的 本研究采用射频热凝毁损腰交感神经节,探讨背根神经节(DRG)Nav1.8磷酸化在大鼠糖尿病痛性周围神经病变中的作用。方法 采用腹腔注射链尿佐菌素诱导糖尿病痛性周围神经病变大鼠模型,取造模成功的大鼠20只,随机分为糖尿病对照组(D组)及交感神经节射频热凝组(R组),每组10只,另取10只同月龄大鼠为正常对照组(C组)。R组大鼠在X光机介导下行右侧L3,4椎旁腰交感神经节射频热凝毁损。分别于射频热凝前、射频热凝后1、2周时,采用von Frey纤维丝测定大鼠右侧后爪对机械性刺激缩足反应的阈值(PWT);射频热凝后2周,采用Western-blotting方法测定DRG细胞Nav1.8蛋白和苏氨酸磷酸化Nav1.8蛋白表达,并采用透射电镜观察大鼠腓肠神经超微病理结构。结果 与C组比较,射频热凝前D组和R组PWT降低(P<0.01)。射频热凝后1~2周,R组较D组PWT升高,但仍较C组降低(P<0.05)。C组髓鞘排列均匀,轴突内可见形态正常的线粒体;D组脱髓鞘明显,髓鞘板层排列紊乱、断裂、肿胀;R组脱髓鞘程度明显减轻,髓鞘板层局部排列紊乱、空泡形成。与C组比较,D组和R组Nav1.8蛋白表达降低(P<0.05),而苏氨酸磷酸化Nav1.8蛋白表达增高(P<0.01);R组苏氨酸磷酸化Nav1.8蛋白表达低于D组(P<0.05)。结论 DRG细胞Nav1.8的磷酸化可能是糖尿病痛性周围神经病变大鼠痛觉过敏形成的机制之一。  相似文献   
40.
目的探讨硬膜外腔注射生理盐水对剖宫产术患者腰麻效果的影响。方法择期行子宫下段剖宫产术患者60例,年龄24~30岁,体重59~73 kg,随机分为2组,每组30例,A组蛛网膜下腔注射规定剂量的0.75%布比卡因后硬膜外腔注射生理盐水5 ml;B组蛛网膜下腔注射0.75%布比卡因。按序贯法进行试验,设定布比卡因的起始剂量为9 mg,剂量梯度为1.5 mg,若上一例有效,则下一例递减一个剂量梯度,若无效则下一例递增一个剂量梯度,蛛网膜下腔阻滞有效的标准为注射布比卡因后20 min内阻滞上平面达T5。采用概率单位法计算ED50。结果A组布比卡因的ED50(5.8 mg)低于B组(8.1 mg),两组比值为0.72,95%置信区间为0.27~0.98,区间范围不包括1,差异有统计学意义(P〈0.05)。结论硬膜外腔注射生理盐水可增强剖宫产术患者腰麻的效果。  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