全文获取类型
收费全文 | 17743篇 |
免费 | 1178篇 |
国内免费 | 520篇 |
专业分类
耳鼻咽喉 | 57篇 |
儿科学 | 348篇 |
妇产科学 | 227篇 |
基础医学 | 1127篇 |
口腔科学 | 337篇 |
临床医学 | 1125篇 |
内科学 | 1720篇 |
皮肤病学 | 328篇 |
神经病学 | 624篇 |
特种医学 | 302篇 |
外国民族医学 | 1篇 |
外科学 | 1828篇 |
综合类 | 2978篇 |
一般理论 | 1篇 |
预防医学 | 1816篇 |
眼科学 | 205篇 |
药学 | 1768篇 |
6篇 | |
中国医学 | 4157篇 |
肿瘤学 | 486篇 |
出版年
2024年 | 83篇 |
2023年 | 341篇 |
2022年 | 542篇 |
2021年 | 675篇 |
2020年 | 648篇 |
2019年 | 962篇 |
2018年 | 823篇 |
2017年 | 793篇 |
2016年 | 638篇 |
2015年 | 576篇 |
2014年 | 1157篇 |
2013年 | 1089篇 |
2012年 | 1114篇 |
2011年 | 1197篇 |
2010年 | 948篇 |
2009年 | 788篇 |
2008年 | 724篇 |
2007年 | 816篇 |
2006年 | 692篇 |
2005年 | 623篇 |
2004年 | 490篇 |
2003年 | 542篇 |
2002年 | 359篇 |
2001年 | 334篇 |
2000年 | 310篇 |
1999年 | 263篇 |
1998年 | 133篇 |
1997年 | 162篇 |
1996年 | 170篇 |
1995年 | 129篇 |
1994年 | 106篇 |
1993年 | 100篇 |
1992年 | 100篇 |
1991年 | 76篇 |
1990年 | 56篇 |
1989年 | 71篇 |
1988年 | 59篇 |
1987年 | 58篇 |
1986年 | 59篇 |
1985年 | 80篇 |
1984年 | 83篇 |
1983年 | 67篇 |
1982年 | 61篇 |
1981年 | 62篇 |
1980年 | 54篇 |
1979年 | 42篇 |
1978年 | 36篇 |
1977年 | 29篇 |
1976年 | 27篇 |
1973年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Rebecca A. Adams David C. Dollahite Kathleen R. Gilbert Robert E. Keim 《Family relations》2001,50(1):41-48
This article describes the development of the Ethical Principles and Guidelines for Family Scientists that the National Council on Family Relations Board of Directors unanimously approved. Furthermore, it discusses the importance of ethics education for family professionals and provides suggestions for educators. Finally, the ethical principles and guidelines are delineated. We argue that the development of a scholarship on ethics education is important for current and future family scientists. 相似文献
72.
目的 探讨急性脑梗死患者血清补体C1q/肿瘤坏死因子相关蛋白3(CTRP-3)、D-二聚体、可溶性髓样细胞触发受体2(sTREM2)水平及相关临床特征与溶栓后出血性转化(HT)的关系。方法 回顾性分析2018年9月—2022年9月在青海省人民医院接受溶栓治疗的120例急性脑梗死患者的临床资料,根据患者溶栓后是否发生HT分为HT组(30例)、非HT组(90例)。比较两组患者的临床资料及血清CTRP-3、D-二聚体、sTREM2水平。采用多因素逐步Logistic回归分析急性脑梗死患者溶栓后发生HT的危险因素;绘制受试者工作特征(ROC)曲线,分析急性脑梗死患者溶栓后HT预测模型预测HT发生的价值。结果 HT组心房颤动(以下简称房颤)、大面积脑梗死、入院NIHSS评分≥ 15分占比高于非HT组(P <0.05),血清CTRP-3水平低于非HT组(P <0.05),D-二聚体、sTREM2水平高于非HT组(P <0.05)。血清CTRP-3、D-二聚体、sTREM2水平预测急性脑梗死患者溶栓后发生HT的敏感性分别为66.7%(95% CI:0.598,0.756)、70.0%(95% CI:0.607,0.812)、80.0%(95% CI:0.714,0.889),特异性分别为73.3%(95% CI:0.636,0.821)、86.7%(95% CI:0.778,0.923)、86.7%(95% CI:0.747,0.942)。多因素Logistic逐步回归分析结果显示,房颤[O^R=1.237(95% CI:1.103,1.387)]、大面积脑梗死[O^R=2.338(95% CI:1.292,4.231)]、入院NIHSS评分≥ 15分[O^R=2.087(95% CI:1.231,3.538)]、CTRP-3 ≤ 269.265 μg/L [O^R=3.006(95% CI:1.508,5.992)]、D-二聚体≥ 2.625 mg/L [O^R=2.649(95% CI:1.374,5.107)]、sTREM2 ≥ 314.675 ng/L [O^R=2.328(95% CI:1.411,3.841)]是急性脑梗死患者溶栓后发生HT的危险因素(P <0.05)。根据多因素Logistic逐步回归分析结果建立急性脑梗死患者溶栓后HT预测模型,Logit(P) = -33.887 + 0.213×房颤+ 0.849×大面积脑梗死+0.736×入院NIHSS评分+ 1.101×CTRP-3 + 0.974×D-二聚体+ 0.845×sTREM2;ROC曲线分析结果表明,预测模型预测HT发生的敏感性为93.3%(95% CI:0.841,0.991),特异性为87.8%(95% CI:0.808,0.976)。结论 血清CTRP-3、D-二聚体、sTREM2水平与急性脑梗死患者溶栓后HT有关,预测价值较高,且急性脑梗死患者溶栓后HT预测模型预测HT优于各项指标单独预测。 相似文献
73.
采用耳廓视诊、耳廓电探测、耳廓染色三种手段,对116例恶性肿瘤病人、120例良性疾病病人和115例健康人进行对照检查证明:恶性肿瘤病人在耳廓上的相应部位软骨增生,耳轮色素沉着,Y_2软骨增生,耳廓上代表癌区的部位及肿瘤在耳廓上的相应部位电流增大;染色时,耳轮、Y_1~Y_7(注)及耳廓相应部位着色。而一般疾病组除耳廓相应部位电流增大,染色着色及充血、血疹外,耳廓上癌区基本上无阳性反应。健康人组通过三种手段检查,基本上无阳性反应。经统计学处理有极显著差异(P<0.01)。双盲法验证,准确率达92.65%。 相似文献
74.
Allegria Kessous Pierre Colombies Martine Sudries Georges Bourrouillou Jacques Pris Danielle Clement 《Cancer Genetics and Cytogenetics》1980,2(4):335-337
This report describes a new case of chronic myeloid leukemia with an unusual Philadelphia chromosome translocation involving chromosomes No. 4,9, and 22; t(4,9,22) (q31;q34;q11). 相似文献
75.
Résumé La moelle épinière utilise deux grandes modalités fonctionnelles: l'activité réflexe et l'activité programmée.L'activité réflexe constitute la modalité la plus anciennement connue, elle englobe de nombreux arcs réflexes imprégnés de finalités fort diverses. Ainsi le réflexe myotatique, arc monosynaptique le plus simple, maintient et protège le tonus musculaire; les réflexes à point de départ cutané, polysynaptiques, impliquant des réseaux interneuronaux, extériorisent des réponses motrices de défense et de protection indiquant déjà une compétence plus intégrative.L'activité programmée médullaire est supportée par des circuits neuronaux assez solidement fixés. Cette organisation fonctionnelle produit des séquences motrices correctement agencées dans l'espace et dans le temps (locomotion, miction, défécation, réflexes sexuels).Aces deux modalités basales viennent se superposer les influences supra-spinales à capacité exécutoire. Ces signaux, canalisés vers la voie finale commune, agissent, dans une faible part, directement sur les motoneurones spinaux et, en effet, dans une très large mesure, ils utilisent les circuits interneuronaux et modulent ou déclenchent réflexes et programmes médullaires engendrant ainsi une activité cinétique cohérente. 相似文献
76.
R. Kinscherf V. Hack T. Fischbach B. Friedmann C. Weiss L. Edler P. Bärtsch W. Dröge 《Journal of molecular medicine (Berlin, Germany)》1996,74(7):393-400
Skeletal muscle catabolism, low plasma glutamine, and high venous glutamate levels are common among patients with cancer or human immunodeficiency virus infection. In addition, a high glycolytic activity is commonly found in muscle tissue of cachectic cancer patients, suggesting insufficient mitochondrial energy metabolism. We therefore investigated (a) whether an anaerobic physical exercise program causes similar changes in plasma amino acid levels, and (b) whether low plasma glutamine or high glutamate levels are risk factors for loss of body cell mass (BCM) in healthy human subjects, i.e., in the absence of a tumor or virus infection. Longitudinal measurements from healthy subjects over longer periods suggest that the age-related loss of BCM occur mainly during episodes with high venous glutamate levels, indicative of decreased muscular transport activity for glutamate. A significant increase in venous glutamate levels from 25 to about 40 M was seen after a program of anaerobic physical exercise. This was associated with changes in T lymphocyte numbers. Under these conditions persons with low baseline levels of plasma glutamine, arginine, and cystine levels also showed a loss of BCM. This loss of BCM was correlated not only with the amino acid levels at baseline examination, but also with an increase in plasma glutamine, arginine, and cystine levels during the observation period, suggesting that a loss of BCM in healthy individuals terminates itself by adjusting these amino acids to higher levels that stabilize BCM. To test a possible regulatory role of cysteine in this context we determined the effect of N-acetyl-cysteine on BCM in a group of subjects with relatively low glutamine levels. The placebo group of this study showed a loss of BCM and an increase in body fat, suggesting that body protein had been converted into other forms of chemical energy. The decrease in mean BCM/body fat ratios was prevented by N-acetyl-cysteine, indicating that cysteine indeed plays a regulatory role in the physiological control of BCM.Abbreviations
BCM
Body cell mass
-
HIV
Human immunodeficiency virus type 1
-
NAC
N-Acetyl-cysteine 相似文献
77.
Deborah U Frank Sarah A Elliott Eon Joo Park Jennetta Hammond Yukio Saijoh Anne M Moon 《Developmental dynamics》2007,236(4):1085-1092
We targeted the reverse tetracycline controlled transactivator (rtTA) to the Foxa2 locus (Foxa2(ITA)) to generate a system for regulating Cre-recombinase activity within Foxa2 expression domains, including the endoderm, notochord, and floor plate of early mouse embryos. The use of an internal ribosomal entry site to obtain rtTA expression preserves Foxa2 function of the targeted allele. Cre activity with this system reflects the level of endogenous Foxa2 activity and is also tightly controlled by doxycycline. The location of Cre activity within the broader Foxa2 expression domain can be restricted by altering the timing of doxycycline administration. Isolated floor plate expression can be obtained in this manner. This system will provide a useful tool for manipulating gene expression in endoderm, notochord, and floor plate, all of which are tissues with important structural and patterning functions during embryogenesis. 相似文献
78.
M C Whitehead 《Neuroscience》1979,4(3):379-390
The consequences of depriving the optic tectum of axons from the contralateral eye have been studied in Golgi-impregnated brains from a staged series of chick embryos. Following enucleation at 2–5 days of age, measurements of dendritic length and the numbers of branches at all orders for three cell types were performed with an automated three-dimensional tracking system at various survival times. Dendritic lengths and the number of middle order branches of neurons from control animals, aged 12–14 days (stages 38–40), are greater than those from non-innervated embryos of the same ages. However, by Day 18 (stage 44), no significant differences in length or branching are seen between neurons from control and experimental embryos. Observations of these neurons revealed qualitative differences between experimental and control embryos. Growth cones, varicosities and filopodia, indicators of dendritic differentiation, are more commonly associated with neurons from control Day 12 and 14 embryos, than operated embryos of the same stages. However, at Days 16 and 18 these growth characteristics are more usually seen on neurons from deafferented embryos than from controls.The deleterious effects observed in experimental animals between Days 12 and 14 are presumably caused by the absence of optic fibers. The eventual growth during late embryogenesis, of the cells deprived of optic input, may reflect a trophic influence not acting in the earlier period. 相似文献
79.
The detailed morphology of neurons in the optic tectum of the common goldfish, Carassius auratus, was reinvestigated using rapid Golgi and Golgi-Cox methods. Neurons were classified initially on the basis of the orientation of the primary dendritic processes within the tectum: vertical, horizontal and non-oriented. These 3 groups were subdivided according to the shape of the soma and the axonal and dendritic configurations.The cell types observed in the present study were compared with those reported in earlier analyses of the goldfish optic tectum. Numerous differences, primarily of soma location and axonal origin and pathway for each cell type, were found. The structure of the goldfish optic tectum appears to be quite similar to the tectum of other teleosts. 相似文献
80.
本实验选用具有生育力成年雄性猕猴7只,在直视下行双侧HFMC输精管内注射,每侧剂量分别为30mg1只,60mg和100mg各3只;于注射后2.5年和3.5年分别处死动物,取睾丸组织进行光镜和电镜观察.结果发现:猕猴注射HFMC2.5年后,睾丸光镜大部分曲细精管生精上皮结构完整,排列整齐。仅见局部少数管腔生精上皮层数减少,上皮细胞轻度水样变性等病理改变。电镜下曲细精管内除支持细胞内脂褐素增多,轻度基底膜增厚和精母细胞内质网扩张外,各级生精细胞,支持细胞及细胞间连接复合体等超微结构未见明显异常。注射HFMC3.5年后猕猴的光镜、电镜结果与注射后2.5年结果相似,但局部改变较2.5年组轻。上述结果表明:猕猴输精管内注射一定剂量HFMC节育不会引起睾丸组织的严重病理改变。但是,由于注射HFMC后,HFMC释放H+及其对输精管的暂时阻塞,改变了精子生存的内环境,使睾丸出现局部轻度病理改变,随着HFMC逐渐溶解排出,睾丸功能相继恢复正常,配对产仔。为HFMC应用提供了安全性依据。 相似文献