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   338383篇
  免费   31729篇
  国内免费   19708篇
耳鼻咽喉   3174篇
儿科学   5452篇
妇产科学   2715篇
基础医学   23910篇
口腔科学   6247篇
临床医学   41662篇
内科学   34371篇
皮肤病学   3911篇
神经病学   9288篇
特种医学   11996篇
外国民族医学   32篇
外科学   31055篇
综合类   85457篇
现状与发展   84篇
一般理论   13篇
预防医学   37189篇
眼科学   4892篇
药学   41243篇
  444篇
中国医学   29358篇
肿瘤学   17327篇
  2024年   1569篇
  2023年   4402篇
  2022年   10999篇
  2021年   13929篇
  2020年   12022篇
  2019年   7292篇
  2018年   7669篇
  2017年   9497篇
  2016年   7622篇
  2015年   13100篇
  2014年   17238篇
  2013年   20545篇
  2012年   29749篇
  2011年   31436篇
  2010年   26919篇
  2009年   24115篇
  2008年   25604篇
  2007年   24464篇
  2006年   22005篇
  2005年   18445篇
  2004年   12870篇
  2003年   10658篇
  2002年   8456篇
  2001年   7584篇
  2000年   6368篇
  1999年   3538篇
  1998年   1613篇
  1997年   1538篇
  1996年   1270篇
  1995年   1203篇
  1994年   1023篇
  1993年   638篇
  1992年   692篇
  1991年   591篇
  1990年   529篇
  1989年   442篇
  1988年   355篇
  1987年   370篇
  1986年   294篇
  1985年   240篇
  1984年   161篇
  1983年   117篇
  1982年   104篇
  1981年   47篇
  1980年   37篇
  1979年   47篇
  1966年   25篇
  1965年   23篇
  1963年   26篇
  1957年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
大鼠自体异体表皮细胞悬液混合移植的实验研究   总被引:3,自引:2,他引:1  
目的 探讨自、异体表皮细胞悬液混合移植技术在创面修复中的应用。 方法  30只大鼠随机配成 15对后 ,分成细胞悬液移植组 (A组 ,10对 )和细胞膜片移植组 (B组 ,5对 )。取每只大鼠全厚皮 ,分离表皮细胞 ,并根据配对情况按 1∶1的细胞比例混合 ,体外常规培养。 4d后收获A组混合细胞悬液 ,14d后收获B组混合细胞膜片。将此细胞悬液和膜片分别转移至A、B组相应供体大鼠的去全厚皮创面。随后A组每对大鼠的创面交叉覆盖配对方的异体全厚皮 ;B组创面覆盖胶原膜及“优妥”敷料。比较移植后 2~ 3周两组的创面修复情况。 结果 术后 2~ 3周 ,A组创面大多愈合 ,表面光滑 ,与皮下连接紧密。术后第 5天 ,B组创面部分细胞膜片脱落 ,部分成活 ,膜片成活的创面后期再次出现小创面 ,经久不愈。 结论 自、异体表皮细胞悬液混合移植是一种可行的、体内构建皮肤、修复创面的方法。  相似文献   
82.
L-asparaginase, an effective antileukemia and antilymphoma agent, is toxic to many organ systems. We report a case of ureteral obstruction caused by L-asparaginase via the inflammatory complication of acute pancreatitis. The patient was an 11-year-old boy with acute lymphoblastic leukemia. Six days after completing a 4-week induction therapy containing 9 doses of L-asparaginase, severe left abdominal pain developed. Abdominal computed tomography showed phlegmon formation anterior to the pancreatic head and in the left posterior pararenal space. The strands of inflammatory soft tissues encased the upper third of the left ureter, causing left hydroureter and left hydronephrosis. The ureteral obstruction resolved after insertion of a double-J catheter that remained in place for 66 days. This case suggests that L-asparaginase may play a role in the pathogenesis of ureteral obstruction in children receiving chemotherapy.  相似文献   
83.
Submitral ventricular aneurysm is a thoroughly studied pathology but is not well known due to its rarity. Clinically, it is manifested by symptoms and signs of heart failure, mitral regurgitation and/or ventricular arrhythmias, and may be associated with thromboembolic phenomena and myocardial ischemia due to compression of the coronary arteries by the aneurysm. A rare complication of this type of aneurysm is rupture into the left atrium. Transthoracic echocardiography plays an important role in the definitive diagnosis of this pathology, although the role of transesophageal echocardiography in the evaluation of these patients is less known. We report a case of a submitral ventricular aneurysm complicated by rupture into the left atrium, which was diagnosed by transesophageal echocardiography.  相似文献   
84.
虹吸原理在静脉穿刺中的应用   总被引:6,自引:0,他引:6  
目的 :探讨虹吸原理在静脉穿刺中的应用 ,提高静脉穿刺的成功率。方法 :随机将 84例患者分为两组 ,一组用虹吸穿刺法 ,即将输液瓶放置在离穿刺部位 6 0cm左右的下方穿刺 ;一组用常规法。结果 :两组中用虹吸法立即回血占 88 1% ,用常规方法立即回血占 2 1 4 % ,差异有显著性 (P <0 0 5 )。结论 :此法提高了静脉穿刺成功率。  相似文献   
85.
The activation of membrane-associated phospholipase C is rapidly and transiently induced in the central nervous system by a variety of stimuli. Ischaemic brain injury is one of the situations that leads to a dramatic increase in polyphosphoinositide (PPI) turnover. In this study, stimulation of PPI hydrolysis by glutamate (500 μM) was measured in hippocampal slices from rats up to 21 days after an ischaemic insult of 30 min. Ischaemia was induced using the four-vessel occlusion method. PPI hydrolysis elicited by glutamate was significantly increased in the slices prepared from ischaemic rats 24 h after reperfusion, the accumulation of inositol phosphates (InsPs) and inositol 1,4,5-trisphosphate (InsP3) was 614±74% ( n = 8) and 182±11% ( n = 9) of the basal level respectively. This potentiation was also observed 21 days after ischaemia. Hyper-responsiveness to glutamate was also accompanied by an increase in AIF4-stimulated formation of [3H]inositol phosphates. In addition, global ischaemia did not change either high-affinity [3H]glutamate binding in hippocampal membranes or the stimulation of PPI hydrolysis by carbachol or noradrenaline in hippocampal slices. The present results suggest that the increased responsiveness to glutamate is the result, at least in part, of functional changes at the G-protein level, and may contribute to the pathophysiology of ischaemic brain injury or to the regenerative phenomena that accompany ischaemic damage.  相似文献   
86.
87.
白细胞介素—2新的功能位点及其中枢镇痛作用   总被引:2,自引:0,他引:2  
白细胞介素-2(IL-2)不仅是重要的免疫调节因子,而且还具有重要的中枢调节作用。本实验以钾离子透入引起大鼠甩尾反应为指标,发现侧脑室注射IL—2能显著提高动物痛阈,并能被纳洛酮所阻断,表示IL-2的中枢镇痛作用可能与阿片受体有关。利用基因定位突变技术获得的无免疫活性IL-2实查体仍具有中枢镇痛作用,表明IL—2分子上发挥镇痛和免疫调节作用的功能位点是相互独立的。纳洛酮能够阻断IL—2的中枢镇痛作用,而不能影响IL—2增殖CTLL-2细胞的作用,提示IL-2发挥镇痛和免疫调节作用可能通过不同的受体途径。IL-2分子中第45位Tyr残基突变为Val后,虽仍保留了免疫活性,但丧失了镇痛功能,表示45位Tyr残基是IL—2发挥中枢镇痛功能的关键残基之一。我们推测IL—2的镇痛功能位点可能在IL—2分子中第45位Tyr残基附近区域。  相似文献   
88.
2型糖尿病患者血浆TNF-α水平与胰岛素抵抗的关系   总被引:7,自引:0,他引:7  
目的 探讨 2型糖尿病患者血浆TNF -α水平与胰岛素抵抗的关系。方法 用放免法测定 3 8例非肥胖型 2型糖尿病患者及 3 0例正常人的血浆TNF -α浓度 ,计算胰岛素敏感指数 (ISI)和体重指数 (BMI) ,并将血浆TNF -α分别与ISI、BMI做直线相关分析。结果  2型糖尿病患者血浆TNF -α水平为 3 0 79± 6 64fmol/ml,显著高于正常对照组 ,(P <0 0 0 5 ) ;糖尿病组ISI为 -5 64±0 3 5 ,而正常对照组为 -4 0 4± 0 43 ,二者有显著性差异 (P <0 0 0 1。 2型糖尿病患者血浆TNF -α水平与ISI的相关系数为 -0 67(P <0 0 0 5 ) ,呈显著负相关 ;在女性患者 ,血浆TNF -α水平与BMI呈显著正相关 ,直线回归方程为Y =1 2 19X +2 40 6,r =0 68(P<0 0 0 5 )。结论 非肥胖型 2型糖尿病患者存在胰岛素抵抗 ;非肥胖型 2型糖尿病患者血浆TNF -α水平升高 ,并可间接反映胰岛素抵抗程度  相似文献   
89.
乌贼墨诱生小鼠细胞毒因子活性的检测   总被引:11,自引:2,他引:9  
用乌贼墨处理小鼠后,采集血清。经体外细胞毒实验证明:乌贼墨诱生的血清对人和鼠的肿瘤细胞株均有不同程度的杀伤作用。这一结果提示:乌贼墨可能具有诱生内源性细胞毒因子产生的活性。  相似文献   
90.
Several types of chronic pain syndromes are effectively treated with sodium channel blockers such as lignocaine. Further investigation of this therapeutic modality would be facilitated by refinement of the parameters describing lignocaine distribution and elimination. This would allow precise lignocaine infusion by a computer-controlled infusion to attain and maintain stable target lignocaine concentrations. Arterial blood samples were obtained at frequent intervals during a computer-controlled infusion of lignocaine in 12 adult human volunteers. Plasma lignocaine concentrations of 1, 2, 3, 4 and 5 microg/ml were targeted for 15 min at each concentration. A three-compartment mammillary pharmacokinetic model best described the resulting concentration vs time profile. A population pharmacokinetic analysis was performed using three different techniques; the two-stage, pooled and mixed effects modelling. There was marked overshoot of the plasma concentration above the target prior to refinement of the pharmacokinetic parameters. The best parameters of a three-compartment mammillary model fit to the measured concentration using the pooled data approach were: V(1) = 7.44, V(2) =11.5 and V(3) = 97.71; Cl(1) = 0.585, Cl(2) = 2.23 and Cl(3) =1.64 l/min. Similarly calculated parameters using NONMEM were V(1) = 6.99, V(2) =12.2 and V(3) =1341; Cl(1) = 0.703, Cl(2) =1.24 and Cl(3) =1.49 l/min. The addition of age as a covariate of the pharmacokinetic parameters improved the model in both cases. Height, lean body mass and body surface area as covariates of the pharmacokinetic parameters did not improve the predicted value of the model. Prospective testing of the pharmacokinetic parameters will be required to define whether they function well. The refinement of pharmacokinetic parameters for the computer-controlled intravenous infusion of lignocaine will facilitate further research in pain therapy. Published lignocaine pharmacokinetic values have a relatively large central volume of distribution, and hence, when implemented as a computer-controlled infusion, result in dramatic overshoot shortly after targeting a higher plasma concentration. In light of the long-lasting pain relief provided by sodium channel blockade in neuropathic pain states, overshoot of plasma concentrations must be avoided if the concentration vs effect relationship is to be defined.  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