全文获取类型
收费全文 | 43822篇 |
免费 | 3373篇 |
国内免费 | 1290篇 |
专业分类
耳鼻咽喉 | 241篇 |
儿科学 | 1106篇 |
妇产科学 | 557篇 |
基础医学 | 6856篇 |
口腔科学 | 907篇 |
临床医学 | 3054篇 |
内科学 | 6821篇 |
皮肤病学 | 776篇 |
神经病学 | 3624篇 |
特种医学 | 658篇 |
外国民族医学 | 5篇 |
外科学 | 3503篇 |
综合类 | 5991篇 |
现状与发展 | 4篇 |
预防医学 | 2066篇 |
眼科学 | 506篇 |
药学 | 6547篇 |
4篇 | |
中国医学 | 2047篇 |
肿瘤学 | 3212篇 |
出版年
2024年 | 91篇 |
2023年 | 801篇 |
2022年 | 2000篇 |
2021年 | 1882篇 |
2020年 | 1438篇 |
2019年 | 1592篇 |
2018年 | 1589篇 |
2017年 | 1472篇 |
2016年 | 1343篇 |
2015年 | 1438篇 |
2014年 | 2354篇 |
2013年 | 2620篇 |
2012年 | 2169篇 |
2011年 | 2594篇 |
2010年 | 2065篇 |
2009年 | 2109篇 |
2008年 | 2093篇 |
2007年 | 1871篇 |
2006年 | 1745篇 |
2005年 | 1627篇 |
2004年 | 1558篇 |
2003年 | 1370篇 |
2002年 | 1208篇 |
2001年 | 970篇 |
2000年 | 893篇 |
1999年 | 783篇 |
1998年 | 627篇 |
1997年 | 662篇 |
1996年 | 527篇 |
1995年 | 504篇 |
1994年 | 431篇 |
1993年 | 313篇 |
1992年 | 272篇 |
1991年 | 265篇 |
1990年 | 211篇 |
1989年 | 175篇 |
1988年 | 179篇 |
1987年 | 141篇 |
1986年 | 149篇 |
1985年 | 295篇 |
1984年 | 312篇 |
1983年 | 246篇 |
1982年 | 275篇 |
1981年 | 216篇 |
1980年 | 198篇 |
1979年 | 181篇 |
1978年 | 135篇 |
1977年 | 94篇 |
1976年 | 103篇 |
1975年 | 91篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The effects of bilateral nucleus accumbens microinjections ofd-ala-met-enkephalinamide (DALA) were assessed in behavioral activation and lateral hypothalamic self-stimulation (LHSS) rate-frequency curve-shift paradigms in normal and accumbens 6-OHDA (4.0 µg) treated rats. Microinjections of DALA (2.5 µg/µl) in the behavioral activation paradigm had little effect on normal activity; however, DALA administered to 6-OHDA treated rats produced a significant overall increase in locomotion. The 6-OHDA DALA-induced locomotion effect peaked at 2 weeks after 6-OHDA treatment and then returned to baseline levels by week 5 posttreatment. Using LHSS, DALA tested over a range of doses (2.5, 5, 10, 20 µg/µl) displayed a weak biphasic reward effect only at the highest dose, which was characterized by an initial suppression followed by an elevation. DALA significantly depressed initial operant motor/performance in LHSS in a dose dependent fashion. Micro-injections of the normally ineffective low dose of DALA (2.5 µg/µl) following accumbens 6-OHDA treatment produced a significant LHSS reward decrease 2 weeks posttreatment, while LHSS motor/performance was relatively unaffected. Results are discussed in terms of opiate-dopamine and limbic-motor interactions. 相似文献
72.
73.
应用脉冲多普勒超声心动图对30例使用1,6-二磷酸果糖的肺炎心衰患儿进行心室舒缩功能指标的观测,并以20例常规治疗的心衰患儿及20例正常儿为对照组,评价1,6-二磷酸果糖的疗效。结果表明,1,6-二磷酸果糖能明显改善PEP、PEP/ET、PEP/R-R、FVI和SV等心室收缩功能指标及PFVE、E/A、PFVA等心室舒张功能指标,使心功能恢复正常。1,6-二磷酸果糖对肺炎心衰引起的心肌缺血、缺氧有保护作用。 相似文献
74.
Effects of mycophenolic acid on IL-6 expression of human renal proximal and distal tubular cells in vitro. 总被引:1,自引:0,他引:1
BACKGROUND: Interleukin-6 (IL-6) is a multifunctional cytokine which regulates immune responses and host defence mechanisms. IL-6 has been found to be increased in certain inflammatory conditions of the kidney, in which tubular epithelial cells play a pivotal role. Human renal tubular cells express IL-6. Until now no data about the effect of the immunosuppressant drug mycophenolic acid (MPA) on IL-6 expression were available. METHODS: Proximal and distal tubular epithelial cells (PTC/DTC) have been isolated immunomagnetically. Confluent monolayers were stimulated with interleukin-1beta (IL-1beta; 25 U/ml), IL-1beta+ MPA (0.25-50 micro M) or MPA alone for 48 h. Release of IL-6 protein into the supernatant was evaluated with an enzyme immunoassay, IL-6 mRNA expression was evaluated using the Quantikine mRNA kit. RESULTS: After IL-1beta stimulation, a highly significant 2.6- (PTC) and 3.8-fold (DTC) upregulation of IL-6 expression was detectable. IL-6 mRNA was upregulated by IL-1beta [1.57- (PTC) and 2.03-fold (DTC)]. MPA inhibited this cytokine-induced IL-6 expression in a dose-dependent manner. Incubation with the lowest MPA concentration had no effect on the stimulated upregulation, whereas all higher doses significantly decreased IL-6 expression. Dexamethasone significantly inhibited the cytokine-induced IL-6 protein release in PTC, but not in DTC. CONCLUSIONS: In this study we demonstrated for the first time an inhibitory effect of MPA on the stimulated IL-6 expression of renal tubular epithelial cells. In contrast to older data, which showed a synergistic upregulation of the expression of a CC-chemokine by a combination of cytokines and MPA, in the present study we could demonstrate an immunosuppressive effect of MPA on the expression of an important cytokine. 相似文献
75.
白细胞介素-6对椎间盘细胞中蛋白多糖代谢影响的实验研究 总被引:3,自引:0,他引:3
目的:研究白细胞介素-6(interleukin-6,IL-6)对椎间盘纤维环和髓核细胞中蛋白多糖代谢的影响。方法:自然流产的胎儿4例,4h内无菌取出椎间盘,分别进行纤维环和髓核细胞的体外培养。在纤维环细胞的培养液中分别加入IL-60(对照组)、400、800ng/ml,培养24h后,用Alcian法检测培养液中硫酸软骨素的含量。在培养中的髓核细胞中加入IL-60(对照组)、100、400、800ng/ml,培养24h,然后测量培养液中硫酸软骨素的含量。结果:在纤维环细胞中加入IL-6组较不加IL-6对照组培养液中硫酸软骨素的含量增加,在髓核细胞组中加入IL-6组和对照组的差别无显著性。结论:IL-6可以刺激椎间盘纤维环细胞中蛋白多糖的合成,但对髓核细胞中蛋白多糖的合成没有明显的作用。 相似文献
76.
【摘要】 目的 :探讨羊水粪染与羊膜腔感染的关系。方法 :选择未临产且胎膜完整的剖宫产产妇 5 6例 ,根据术中所见羊水性状分为羊水清亮组、羊水Ⅰ~II度粪染组和羊水III度粪染组。于剖宫产术中取羊水用双抗体夹心ELISA法测IL 6含量 ,取胎盘胎膜做病理检查以了解有无炎性细胞浸润 ,并记录新生儿Apgar评分 ,观察产妇术后有无产褥感染。结果 :3组羊水中IL 6含量差异无显著性 ,3组胎盘标本病理检查示炎性细胞浸润之差异亦无显著性 ,而羊水粪染组新生儿窒息发生率较清亮组明显增加 (P <0 .0 5 )。结论 :羊水粪染尤其是III度粪染是胎儿窘迫的标志 ,而与羊膜腔感染无明显相关性。 相似文献
77.
目的对FKBP6基因第3、4外显子进行突变和多态性筛查,研究第3外显子278C/A位点及第2内含子C/T位点(rs7797242)在无精症患者和正常男性中的多态性,初步探讨与原发无精症的相关性。方法采用变性高效液相色谱和聚合酶链反应-限制性片段长度多态性方法,对第3、4外显子进行突变和多态性筛查,对177例无精症患者和231名正常男性的278C/A和C/T(rs7797242)多态性进行基因分型。结果278C和278A等位基因频率符合Hardy-Weinberg平衡。无精症患者278A显著低于正常对照,差异有统计学意义(P<0.05)。C/T多态性在两组中均未检出,第3、4外显子未筛查到新的变异。结论278A等位基因可能与原发无精症相关。C/T(rs7797242)及370G/A,430G/C,467T/C,468G/A在中国人群中非常罕见。 相似文献
78.
N. C. Harris S. A. Greenfield 《Journal of neural transmission (Vienna, Austria : 1996)》1991,3(2):89-98
Summary Intracellular recordings were made from substantia nigra pars compacta neurones in vitro from animals with partial unilateral 6-hydroxydopamine lesions of the nigrostriatal tract. Lesions were assessed and grouped according to the severity of the strital dopamine depletion. No differences were seen between neurones from control and lesioned side nigrae as regards their membrane properties, firing rates, burst activity or percentage of quiescent neurones in any of the lesioned categories. It is concluded that following partial lesioning, the remaining substantia nigra zona compacta neurones in vitro, are functioning normally. 相似文献
79.
巨细胞病毒肝炎患儿血清细胞因子水平测定及其临床意义 总被引:4,自引:2,他引:2
目的 研究巨细胞病毒 (CMV)肝炎患儿血清干扰素 α(IFN α)、白细胞介素 8(IL 8)和肿瘤坏死因子 α(TNF α)水平的变化及其临床意义。方法 应用ELISA法检测 35例CMV肝炎患儿血清中上述三种细胞因子的含量 ,并对其两两之间进行了相关性分析。结果 CMV肝炎组患儿IFN α、IL 8、TNF α的含量分别为 (770 .3± 2 0 5 .4 )ng/L、(41.9± 2 2 .5 )ng/L和 (10 33.2± 388.5 )ng/L ,非常显著高于正常对照组 (P <0 .0 1)。相关性研究发现IFN α与TNF α呈显著正相关 (r =0 .35 6 ,P <0 .0 5 )。结论 血清细胞因子明显增高与CMV肝炎的病理变化和病损程度有着密切的联系 相似文献
80.
George Wolf DPhil 《Nutrition reviews》2007,65(8):385-388
Retinol-binding protein (RBP) is the transport protein that carries retinol in the circulation from the liver to its target tissues. The existence of a cell-surface receptor on the target cells, which mediates the uptake of retinol from RBP, has been known since 1975. Recently, it was identified as an integral transmem-brane protein named STRA6 that is inducible by retinoic acid in certain cancer cells. The receptor was found to be highly specific for RBP, with high affinity, and to be localized in all tissues known to require retinol for their function, particularly the pigment epithelium of the eye. 相似文献