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   2941篇
  免费   254篇
  国内免费   127篇
耳鼻咽喉   3篇
儿科学   179篇
妇产科学   3篇
基础医学   434篇
口腔科学   4篇
临床医学   220篇
内科学   354篇
皮肤病学   23篇
神经病学   23篇
特种医学   43篇
外科学   1003篇
综合类   523篇
现状与发展   1篇
预防医学   41篇
眼科学   18篇
药学   183篇
  1篇
中国医学   261篇
肿瘤学   5篇
  2024年   5篇
  2023年   49篇
  2022年   74篇
  2021年   140篇
  2020年   84篇
  2019年   88篇
  2018年   99篇
  2017年   72篇
  2016年   93篇
  2015年   103篇
  2014年   147篇
  2013年   208篇
  2012年   115篇
  2011年   158篇
  2010年   105篇
  2009年   111篇
  2008年   103篇
  2007年   116篇
  2006年   105篇
  2005年   117篇
  2004年   127篇
  2003年   110篇
  2002年   101篇
  2001年   120篇
  2000年   83篇
  1999年   61篇
  1998年   59篇
  1997年   63篇
  1996年   60篇
  1995年   56篇
  1994年   49篇
  1993年   57篇
  1992年   49篇
  1991年   28篇
  1990年   35篇
  1989年   23篇
  1988年   22篇
  1987年   15篇
  1986年   15篇
  1985年   20篇
  1984年   15篇
  1983年   9篇
  1982年   6篇
  1981年   5篇
  1980年   10篇
  1979年   6篇
  1978年   7篇
  1977年   8篇
  1976年   5篇
  1974年   3篇
排序方式: 共有3322条查询结果,搜索用时 140 毫秒
51.
We carried out an immunohistochemical study of tissue-type plasminogen activator (PA) and urokinase-type PA, and their inhibitors, PA inhibitor-1 and PA inhibitor-2, using renal biopsy specimens obtained from 86 patients with various forms of glomerulonephritis. The controls were four normal renal tissue specimens. On immunofluorescent observation, granular staining for tissue-type PA was found to be distributed along the glomerular capillary walls. The fluorescence was weak in the normal renal tissue and occasionally intense in the tissues of patients with IgA nephritis, minimal change nephrotic syndrome, and lupus nephritis. PA inhibitor-1 was abundant in the glomerular epithelial cells and scarce in the mesangial area and glomerular capillary lumens of the normal renal tissues. This was confirmed by immunoelectron microscopy using gold staining. The fluorescence of PA inhibitor-1 was weaker in some specimens of nephritic tissues than in the normal renal tissues. Urokinase-type PA and PA inhibitor-2 were negative within the glomeruli in all the specimens. In the glomerulonephritic tissues which were fibrin deposition-positive, tissue-type PA expression in the glomeruli tended to be strong. An association between fibrin deposition and PA inhibitor-1 staining was not clear. These data suggest that expression of tissue-type PA in the glomeruli increases in association with fibrin deposition.  相似文献   
52.
Anti-glomerular basement membrane (GBM) glomerulonephritis induced in WKY rats is characterized by glomerular accumulation of CD8(+) T cells and monocytes/macrophages, followed by crescent formation. The mechanism of leukocyte accumulation after antibody binding to GBM is still unclear. To unveil an involvement of Fcgamma receptors (FcgammaR) in leukocytes recruitment we examined the expression of FcgammaR in glomeruli and the effects of the administration of F(ab')(2) fragment of anti-GBM antibody or FcgammaR blocking on the initiation and progression of this model. A gradual increase of FcgammaR mRNA expression in glomeruli during the time course of disease suggested their significance in the development of glomerulonephritis. Glomerular lesions and proteinuria were induced only in rats injected with intact IgG of anti-GBM antibody, but not with the F(ab')(2) fragment. In vivo blocking of FcgammaR by administering heat-aggregated IgG led to the decrease of mRNA expression for all types of FcgammaR (types 1, 2 and 3) and a significant amelioration of glomerulonephritis manifestations. By flow cytometry and immunohistochemistry FcgammaR2-expressing cells in glomeruli were identified as macrophages, but not CD8(+) T cells. The expression of FcgammaR1 and 3 was significantly decreased, and that of FcgammaR2 became undetectable in CD8(+) T cell-depleted rats. Thus, CD8(+) T cells may stimulate FcgammaR expression on macrophages, contributing to their glomerular accumulation and injury. These studies provide direct evidence for a crucial involvement of IgG Fc-FcgammaR interaction in glomerular recruitment of macrophages and following induction of anti-GBM glomerulonephritis in WKY rats.  相似文献   
53.
Fixed anionic charges in the mammalian glomerulus, on both the basement membrane and the epithelial cell foot processes, are believed to form an important part of the glomerular filtration barrier. There is good evidence that their loss causes proteinuria. The charges can be visualized ultrastructurally using cationic dyes, but the requirement of these techniques for perfusion or immersion of fresh tissue has largely confined such studies to experimental models. We have extended the widely used polyethyleneimine technique, to study the charge of glomerular basement membranes in human tissue reprocessed out of paraffin blocks up to 10 years old. We studied selected cases of glomerular disease, where the diagnosis was not in any doubt. In the majority of diseases studied, a continuous charge layer persisted despite severe abnormalities of the basement membrane. Two exceptions were found. In amyloidosis, accumulation of fibrils was associated with a considerable decrease or loss of stainable basement membrane charge. In S.L.E., numerous small defects in the charge layer were noted. The persistence of charge is contrary to reported findings in several animal models of glomerular disease, including puromycin nephrosis, Heymann nephritis and streptozotocin diabetes. Although this method is not subject to precise quantitative analysis, we conclude that in the majority of cases, proteinuria in man is not caused by an extensive loss of glomerular basement membrane anionic charge.  相似文献   
54.
Summary Renal biopsies of 44 patients with endocapillary acute glomerulonephritis (gn) and 64 patients with moderately severe mesangioproliferative gn were investigated morphometrically (point-counting-method, tubulometry).In both gn's statistically significant positive correlations between relative interstitial volume and the concentration of serum creatinine at the time of biopsy were found.Despite severe glomerular lesions the serum creatinine concentration is not increased in most cases of endocapillary acute gn, providing the relative interstitial volume is not increased by more than 15%.Increased serum creatinine concentration without a markedly enlarged interstitium was found in 11 cases of endocapillary acute gn with clinically and morphologically proven acute renal failure. In these cases the glomerular function is probably impaired by the Thurau-mechanism.In all other patients, especially in those with moderately severe mesangioproliferative gn, the serum creatinine concentration rises with an enlargement of relative interstitial volume. This reduction of renal function may be explained by a decrease to the total cross-sectional area of postglomerular vessels, caused by interstitial fibrosis. That may possibly lead to diminished renal blood flow and glomerular filtration with an increase of the serum creatinine concentration.Supported by the Deutsche Forschungsgemeinschaft  相似文献   
55.
Our previous studies have indicated that the IgG-binding M-family proteins (IgGBP) of group A streptococci may be involved in eliciting experimental acute poststreptococcal glomerulonephritis (APSGN) in the rabbit. These surface proteins were also found to trigger production of anti-IgG, which might conceivably act to enhance renal deposition of immune complexes (IC). In the present study, a clinical isolate of serotype M22 (strain AL168), an isogenic double mutant deficient for both the IgGBPs Mrp and Emm, as well as mutants deficient in only one of the proteins were tested for capacity to induce glomerulonephritis. Streptococci to be used for injecting rabbits were heat-killed. Surface-bound IgG was removed by 1 M KSCN and cells were then repeatedly washed in PBS before use. Rabbits were injected intravenously with 109 cells three times a week for 8 weeks and, following one month of rest, for another 6 weeks. Deposits of IgG and C3 as well as induced chemokines TNF-alpha, IL-1beta and IL-6 were traced in cryostat sections using specific antibodies and appropriate peroxidase-labelled anti-antibodies. In four rabbits immunized with the double mutant strain, no deposits were found, and as examined by TEM, only subtle and transient renal changes were observed. In contrast, the original strain AL168 induced pronounced inflammatory and degenerative glomerular changes in all four rabbits injected, and deposits of TNF-alpha, IL-1beta and IL-6 were found in mesangial and endothelial cells. Similar deposits and glomerular changes were seen in all eight rabbits injected with the mrp-emm+ mutant and in four out of seven animals receiving the mrp+emm- mutant. There was a highly significant correlation between high levels of circulating anti-IgG and development of APSGN. These results confirm an important role of streptococcal IgGBP in triggering experimental APSGN as earlier proposed by our group.  相似文献   
56.
四种祛风类中药治疗原发性肾小球肾炎的临床研究   总被引:1,自引:0,他引:1  
目的 :评价口服火把花根、祖师麻、清风藤碱和雷公藤多甙单独与联合用药治疗原发性肾小球肾炎的效果。方法 :选择 6 5 6例经单味或两味祛风类中药治疗的原发性肾小球肾炎患者 ,观察不同治疗患者的临床表现、尿蛋白定量、尿常规、肝肾功能等指标变化。结果 :单味药治疗肾炎的缓解率为 2 4.0 %~ 44 .5 % ,两味药联合治疗肾炎的缓解率为 5 1.9%~ 5 9.2 % ;清风藤碱治疗的各种临床表现的肾炎缓解率均低于其他治疗组 ,单味药火把花根、祖师麻和雷公藤多甙对单纯性蛋白尿的缓解率为 5 0 .0 %~ 6 9.7% ,对单纯性血尿的缓解率为 36 .0 %~ 5 0 .0 % ,对蛋白尿合并血尿的缓解率为 19.5 %~ 2 2 .7% ,联合用药对各种表现的缓解率均高于单味药组 ,对单味药未缓解的部分病例两味药治疗仍有一定效果 ,复发率低于单味药组 ;联合用药组消化道反应、肾功能损害、停经和白细胞减少发生率与单味药组均无明显差别 ,转氨酶增高发生率增加 ,但谷丙转氨酶 >10 0 U /L者少见。结论 :四种祛风类单味药对肾小球肾炎均有一定疗效 ,联合治疗能够显著增加对肾小球肾炎的疗效  相似文献   
57.
BackgroundThe therapeutic effects of tacrolimus (TAC) versus cyclophosphamide (CTX) were not fully illustrated for patients with idiopathic membranous nephropathy (IMN).MethodsThe PubMed, EmBase, Cochrane library, and CNKI were systematically searched throughout March 2020 for randomized controlled trials evaluating the therapeutic effects of TAC versus CTX for IMN patients treated with steroids. The pooled relative risks (RRs) and weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated using the random-effects model.ResultsTwelve trials recruited a total of 868 IMN patients were identified and contained in final meta-analysis. Patients in TAC group was associated with an increased incidence of overall remission (12 trials: 868 patients; RR: 1.21; 95% CI: 1.11–1.31; p < 0.001) and complete remission (12 trials: 868 patients; RR: 1.50; 95% CI: 1.25–1.80; p < 0.001). Moreover, we noted TAC therapy significantly reduced urinary protein excretion (9 trials: 567 patients; WMD: −1.06; 95%CI: −1.41 to −0.71; p < 0.001), and increased serum albumin (9 trials: 567 patients; WMD: 5.37; 95%CI: 2.97 to 7.77; p < 0.001) than CTX therapy. Furthermore, no significant difference between TAC and CTX for serum creatinine was detected (6 trials: 378 patients; WMD: 0.15; 95%CI: −3.46 to 3.75; p = 0.936). Finally, the risk of alopecia (p = 0.008), infection (p = 0.045), leukocytosis (p = 0.002), and elevated ALT/AST (p = 0.011) in TAC group was significantly lower than CTX group, whereas TAC was associated with an increased risk of tremor than CTX (p = 0.010).ConclusionsThis study found IMN patients treated with TAC combined with steroids provides a better therapeutic effect and less adverse events than those treated with CTX combined with steroids, with moderate-certainty evidence.  相似文献   
58.
孟曦  丁伟  王建美  王耀光 《天津中医药》2023,40(10):1320-1326
[目的] 观察膜肾1号方对膜性肾病大鼠肾脏病理的改善作用及其对自噬通路磷脂肌醇3-激酶(PI3K)/蛋白激酶B(AKT)/雷帕霉素靶蛋白(mTOR)相关蛋白表达的影响。[方法] 将大鼠随机分为对照组、模型组、膜肾1号方高剂量组、中剂量组、低剂量组,盐酸贝那普利组。采用大鼠尾静脉注射阳离子化牛血清白蛋白(C-BSA)的方法建立MN大鼠模型,灌胃、取材。苏木精-伊红(HE )染色法观察大鼠肾脏组织病理改变;免疫球蛋白G(IgG)免疫荧光染色观察大鼠IgG沉积;蛋白免疫印迹法(Western Blot)检测PI3K/Akt/mTOR 信号通路相关蛋白及自噬相关蛋白轻链3(LC3)表达。[结果] 药物干预后,膜肾1号方组大鼠24 h尿蛋白、三酰甘油、总胆固醇、低密度脂蛋白下降且低于模型组,并具有统计学差异(P<0.05)。光镜下观察,HE染色示正常组肾组织整体结构基本正常,膜性肾病(MN)模型组肾小球毛细血管丛充血,系膜增生,基底膜出现增厚,部分肾小管细胞空泡变、组织内可见炎症细胞浸润,可见嗜复红蛋白及IgG沉积。经膜肾1号方和盐酸贝那普利干预后,大鼠肾脏病理学改变均有所减轻。各组大鼠IgG沉积显示,与对照组比较模型组IgG沉积明显,IgG荧光表达升高,差异具有统计学意义(P<0.05),盐酸贝那普利组和膜肾1号方组IgG荧光表达下降且低于模型组,具有统计学差异(P<0.05)。Western Blot检测显示,药物干预后,盐酸贝那普利组和膜肾1号方组大鼠PI3K-Akt信号通路相关蛋白表达下降,LC3 表达增加,并具有统计学差异(P<0.05)。[结论] 膜肾1号方可改善大鼠肾脏病理损伤,膜肾1号方干预后PI3K-Akt信号通路相关蛋白磷酸化磷酸肌醇3激酶(p-PI3K),磷酸化Akt蛋白(p-Akt),磷酸化雷帕霉素靶蛋白(p-mTOR)表达明显降低,自噬相关蛋白LC3表达升高,其分子机制与自噬信号通路的调控有关。  相似文献   
59.
复方黄芪袋泡饮改善慢性冠脉供血不足的研究   总被引:1,自引:0,他引:1  
复方黄芪袋泡饮改善慢性冠脉供血不足的研究刘志泉*陈跃*李岩飞*丁煜*为寻找一种比传统扩血管药物更为有效的中西药复方制剂以改善冠脉血供,降低心绞痛和心肌梗塞的发生率,我们依据中西药理论,结合现代血液流变学和微循环的科研成果,研制了以黄芪、阿司匹林为主要...  相似文献   
60.
经皮穿刺封堵室间隔膜部缺损的应用解剖   总被引:4,自引:0,他引:4  
目的:为经皮穿刺室间隔膜部缺损的封堵术提供应用解剖学基础。方法:解剖测量38例(男25.女13)正常成年人的心标本的室间隔膜部及周围结构。结果:室间隔膜部的形态可分为三角型、圆型和椭圆型;各型的出现率分别为58%(22例)、23.7%(9例)和18.3%(7例)。室间隔膜部在左室面的高度为(8.79±2.27)mm。右室面高度为(6.43±1.43)mm。室间隔膜部的长度为(9.37±2.52)mm。室间隔膜部上、下、前、后方和中点的厚度分别为(0.80±0.19)mm、(0.70±0.16)mm、(0.78±0.28)mm、(0.75±0.1 5)mm和(0.52±0.13)mm。结论:室间隔膜部以三角型为主,多位于室上嵴的后缘,膜部的左室面高于右室而和靠近右室面,建议封堵器的左室面的面积应大于右室面。  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