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   36210篇
  免费   2273篇
  国内免费   1239篇
耳鼻咽喉   63篇
儿科学   910篇
妇产科学   668篇
基础医学   1922篇
口腔科学   60篇
临床医学   4257篇
内科学   11067篇
皮肤病学   43篇
神经病学   862篇
特种医学   892篇
外科学   2636篇
综合类   7114篇
现状与发展   5篇
预防医学   2062篇
眼科学   703篇
药学   4749篇
  27篇
中国医学   1524篇
肿瘤学   158篇
  2024年   60篇
  2023年   501篇
  2022年   837篇
  2021年   1230篇
  2020年   1246篇
  2019年   1071篇
  2018年   1155篇
  2017年   1094篇
  2016年   1178篇
  2015年   1173篇
  2014年   2376篇
  2013年   3262篇
  2012年   1914篇
  2011年   1988篇
  2010年   1737篇
  2009年   1616篇
  2008年   1555篇
  2007年   1721篇
  2006年   1542篇
  2005年   1309篇
  2004年   1209篇
  2003年   1113篇
  2002年   931篇
  2001年   909篇
  2000年   768篇
  1999年   650篇
  1998年   558篇
  1997年   601篇
  1996年   500篇
  1995年   525篇
  1994年   438篇
  1993年   306篇
  1992年   321篇
  1991年   263篇
  1990年   231篇
  1989年   196篇
  1988年   208篇
  1987年   176篇
  1986年   161篇
  1985年   206篇
  1984年   189篇
  1983年   88篇
  1982年   118篇
  1981年   118篇
  1980年   123篇
  1979年   61篇
  1978年   44篇
  1977年   46篇
  1976年   40篇
  1973年   16篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
本文报告一种新的改良式远端脾肾静脉分流术,即脾静脉与左肾静脉侧侧吻合、脾静脉远端结扎,再将胃冠状静脉结扎。作者经治7例,初步观察疗效较好,术后无死亡,无复发出血,无肝性脑病发生。本文对这种手术的步骤和优点进行了讨论和分析。  相似文献   
92.
Aims and Objectives The significance of beaten copper appearance (BCA) on skull radiographs in children following surgery for isolated sagittal craniosynostosis has not been studied. This study was designed to look for any correlation between BCA and symptoms suggestive of intracranial hypertension in this group of patients. Materials and Methods Forty-eight consecutive children, who were operated for isolated sagittal synostosis from1987 to 2000 and had postoperative skull radiographs, were included. Patients were divided into: (a) BCA group (n = 20), consisting of children who had beaten copper appearance on skull radiographs at last follow up, and (b) Non-BCA group (n = 28), consisting of children who did not have this finding. Records were reviewed to look for symptoms suggestive of intracranial hypertension, such as headache, head banging, and irritability. Results Median age at surgery was 4.8 months for BCA group and 4 months for the non-BCA group. Follow up ranged from 4 to 156 months with a mean of 36.2 months. Total of 28.6% (n = 6) of the children with follow up radiographs done at ≤18 months of age had BCA. The incidence of BCA increased to 83.3% in children with skull radiographs performed after 48 months of age. In 18 (90%) children, the BCA was ‘diffuse’ with 5 (25%) children having the maximum possible score of 8. In the BCA group, 45% (n = 9) had symptoms compared to 10.7% (n = 3) in the control group (p = 0.0068). Conclusions This study suggests a significant number of children with BCA on radiographs develop symptoms suggestive of raised ICP following surgical treatment in infancy and prolonged follow up may be warranted in this group of patients.  相似文献   
93.
久强脑立清对自发性高血压大鼠重要器官的保护作用   总被引:3,自引:3,他引:0  
目的探讨久强脑立清 (JNQ )对自发性高血压大鼠 (SHR)重要器官心、脑、肾组织形态学的影响。方法动物分为 4组 ,Wistar大鼠对照组、SHR组、SHR服用JNQ高剂量组 (0 5 3 0g/kg)和低剂量组 (0 2 65 g/kg) ,给药 5周。采用尾脉搏测压法测定动物血压 ;动物经组织灌流后 ,低温下快速取出心、脑、肾 ,固定于 10 %福尔马林中 ,4℃保存 ,常规组织切片 ,HE染色。结果给药前各组SHR的血压明显高于对照组 (P <0 0 1) ,给药 3周和 5周后血压未见明显下降。组织病理结果显示 ,未治疗组SHR心肌细胞肥大 ,肌束间小动脉壁增厚 ,官腔变窄 ;大脑皮层血管管腔狭窄 ,管壁增厚 ,血管周围间隙增大 ;肾小球萎缩 ,有玻璃样变。上述病理性改变在经JNQ治疗 5周后得到不同程度的改善 ,以高剂量组明显。结论SHR经JNQ治疗 5周后血压未见明显降低 ,但对重要器官心、脑、肾的病变有较明显改善作用  相似文献   
94.
Objective: To compare renal sodium transport, using fractional excretions of lithium(FELi) as a marker of proximal tubule sodium reabsorption, between hypertensive and non-hypertensive ouabain-treated rats and further to elucidate the role of ouabain in pathogenesis of hypertension. Methods: Thirty male Sprague-Dawley rats weighting 180-200 g were randomly divided into normal control group and ouabain treated group. Rats were infused with 1 ml/kg·d normal saline or 27. 8μg/kg·d ouabain in-traperitoneally once a day respectively. Systolic blood pressure (SBP), heart rate and body weight were recorded weekly. Rats were sacrificed 6 weeks after treatment. Blood and 24-hour urine sample were collected to measure the serum and urinary concentration of sodium, trace lithium and creatinine. Endogenous creatinine clearance rate(Ccr), fractional excretions of sodium (FENa), fractional excretions of lithium (FELi) and fractional reabsorption of sodium in the postproximal tubules (FDRNa) were calculated. Ouabain levels of plasma and renal tissue, plasma renin activity, angiotensin I and aldosterone concentration were determined. Results: 65% of the ouabain-treated rats achieved significantly higher SBP after 4 weeks, compared with that of the saline control groups or self baseline (P<0. 01). But in the other 35% of the ouabain-treated rats, their SBP was similar with control group during the experiment (P>0. 05). The body weight, heart rate and food intake between the 3 groups were no significant differences (P> 0. 05). FELi and FDRNa were significantly lower in ouabain-hypertensive group compared with ouabain-non-hypertensive group and control group(P<0. 01 and P<0. 05). The FEu and FDRn, of ouabain-nonhyper-tensive groups were similar with control group(P>0. 05). Ccr and FENa were comparable between the 3 groups (P>0. 05). Plasma and renal tissue ouabain levels, plasma renin activity, angiotensin I and aldosterone contents in ouabain-hypertensive rats were comparable with ouabain-nonhypertensive rats. Conclusion: Increase of proximal tubule sodium reabsorption play an important role in the pathogenesis of ouabain-hypertensive rats. The change of renal sodium transport may result from regulation to renal Na+ , K + -ATPase by ouabain.  相似文献   
95.
血管内皮生长因子与妊娠高血压综合征发病的关系   总被引:2,自引:0,他引:2  
谢兰  罗军  陈廉  邹冰玉  杨年 《四川医学》2003,24(8):773-775
目的 探讨血管内皮生长因子 (VEGF)在妊娠高血压综合征发病中的作用。方法 分别采用酶联免疫吸附试验检测 40例妊高征孕妇的血清VEGF水平 ,免疫组化检测胎盘及蜕膜组织VEGF及CD3 4表达情况 ,35例正常孕妇作对照。结果 ①妊高征组孕妇的外周血VEGF水平及胎盘组织MVD明显低于正常妊娠组 (P <0 0 5 ) ;②两组胎盘绒毛滋养叶细胞和蜕膜组织中均有VEGF阳性表达 ,胎盘组织强阳性表达高于蜕膜。与对照组比较 ,其胎盘组织VEGF强阳性表达的轻度妊高征无显著性差异 ;而中度和重度妊高征与对照组相比 ,则明显降低 ,差异显著 (P <0 0 5 )。各组孕妇蜕膜组织中VEGF的表达强度和差异无显著性。③孕妇外周血VEGF水平与新生儿出生体重 (r =0 2 9,P <0 0 5 )和胎盘重量 (r =0 34,P <0 0 1)均存在直线正相关关系。结论 妊高征患者血清VEGF水平和胎盘组织MVD降低 ,胎盘组织VEGF表达明显下降 ,都可能在妊高征的发病中起一定的作用。  相似文献   
96.
The renin-angiotensin system is involved in control of blood pressure and salt and fluid homeostasis. Genes for components of this system have been of major focus in research on the causation of the common, complex, polygenic trait, essential hypertension (HT). Association of an A→C variant at nucleotide 1166 of the angiotensin II type 1 receptor (AT1R) gene with HT, but an absence of linkage of this locus with this disease, has been reported recently. Since confirmation in a different setting is imperative, we performed a cross-sectional case-control study of the A1166C variant in a well-characterized group of 108 Caucasian HT subjects with a strong family history (two affected parents) and early onset disease. Genotyping was by mismatch polymerase chain reaction/ Bfr I restriction fragment length polymorphism analysis. Frequency of the C1166allele was 0.40 in HTs and 0.29 in normotensives. The difference in genotype (χ2= 13, P = 0.0015) and allele (χ2= 5.3, P = 0.02) frequencies between the two groups was significant (odds ratio for CC vs AA+AC = 7.3 [95% CI, 1.9–31.9). The present results implicate the AT1R gene, or a locus in linkage disequilibrium with the variant tested, in the causation of essential HT.  相似文献   
97.
Ascites is one of the earliest and most common complications of patients with cirrhosis. A typical circulatory dysfunction characterized by arterial vasodilation, high cardiac output and stimulation of vasoactive systems is commonly present in these patients and is associated with a poor prognosis. The treatment of ascites has been based on the combination of a low-sodium diet and the administration of diuretics. The reintroduction of paracentesis and the recent introduction of the transjugular intrahepatic portosystemic shunt (TIPS) are the most relevant innovations in the treatment of ascites during the past two decades, although controlled trials in large series of patients are needed to delineate whether TIPS is a safe and useful treatment for these patients.  相似文献   
98.
Antihypertensive drugs are commonly associated with adverse side effects in both clinical and laboratory studies. We investigated the sexual sequelae of several major classes of antihypertensive drugs (e.g., beta blockers, central alpha agonists, diuretics) in normal males and in hypertensive patients. We compared the effects of four widely used agents (methyldopa, propranolol, atenolol, hydrochlorothiazide-triamterene) and placebo, in a selected sample of 21 sexually dysfunctional male hypertensives, 13 of whom completed all five phases of the study. Each study drug was administered for a 1-month treatment period, followed by a 2-week, single-blind washout phase, according to a randomized, Latin square crossover design. Dependent variables for the study included a broad range of hormonal, NPT, and self-report measures of sexual response. Results indicated a lack of consistent drug effects on measures of sexual response, although more frequent sexual and nonsexual side effects were observed with methyldopa and propranolol. As in our previous studies, age was negatively correlated with both hormonal and NPT measures, whereas changes in blood pressure were not significantly related to sexual function scores. Results do not support the hypothesis that sexually dysfunctional males are at greater risk for adverse sexual sequelae when treated with centrally active agents or diuretics.  相似文献   
99.
Hepatic venous outflow tract obstruction, Budd-Chiari syndrome (BCS), leads to portal hypertension and to the development of collaterals that bypass the obstruction. Described here is a BCS patient with an unusually large transdiaphragmatic collateral between the left hepatic and left innominate veins, which decompressed the oesophageal varices. This has not been reported earlier in the literature.  相似文献   
100.
张玉洁  李国梁 《广东医学》1998,19(12):909-910
目的:探讨雌激素,胎盘生乳素,钙在妊高征发病中的作用及其相互关系,方法:采用放射免疫法及离心分析钙试剂,测定了42例妊高征患者血清雌二醇,胎盘生乳素,钙,磷及尿钙,磷的含量,34例同期门诊正常孕妇作为对照组,结果:轻度妊高征患者血清雌二醇明显增加(P〈0.05)。重度妊高征患者血清胎盘生乳素显著减少(P〈0.05),轻,中,重度妊高征患者血钙,尿钙含量显著降低(P〈0.05,P〈0.01,P〈0.  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