全文获取类型
收费全文 | 17909篇 |
免费 | 1209篇 |
国内免费 | 714篇 |
专业分类
耳鼻咽喉 | 143篇 |
儿科学 | 381篇 |
妇产科学 | 349篇 |
基础医学 | 3047篇 |
口腔科学 | 745篇 |
临床医学 | 1422篇 |
内科学 | 3058篇 |
皮肤病学 | 268篇 |
神经病学 | 1424篇 |
特种医学 | 389篇 |
外国民族医学 | 2篇 |
外科学 | 1632篇 |
综合类 | 2004篇 |
现状与发展 | 3篇 |
预防医学 | 888篇 |
眼科学 | 345篇 |
药学 | 2073篇 |
3篇 | |
中国医学 | 227篇 |
肿瘤学 | 1429篇 |
出版年
2024年 | 27篇 |
2023年 | 176篇 |
2022年 | 418篇 |
2021年 | 601篇 |
2020年 | 411篇 |
2019年 | 392篇 |
2018年 | 426篇 |
2017年 | 410篇 |
2016年 | 484篇 |
2015年 | 540篇 |
2014年 | 877篇 |
2013年 | 1162篇 |
2012年 | 940篇 |
2011年 | 1079篇 |
2010年 | 953篇 |
2009年 | 1027篇 |
2008年 | 1033篇 |
2007年 | 1009篇 |
2006年 | 904篇 |
2005年 | 872篇 |
2004年 | 741篇 |
2003年 | 644篇 |
2002年 | 531篇 |
2001年 | 475篇 |
2000年 | 374篇 |
1999年 | 366篇 |
1998年 | 290篇 |
1997年 | 293篇 |
1996年 | 254篇 |
1995年 | 251篇 |
1994年 | 210篇 |
1993年 | 149篇 |
1992年 | 165篇 |
1991年 | 158篇 |
1990年 | 138篇 |
1989年 | 120篇 |
1988年 | 90篇 |
1987年 | 81篇 |
1986年 | 60篇 |
1985年 | 104篇 |
1984年 | 108篇 |
1983年 | 83篇 |
1982年 | 75篇 |
1981年 | 74篇 |
1980年 | 59篇 |
1979年 | 50篇 |
1978年 | 42篇 |
1977年 | 39篇 |
1976年 | 19篇 |
1974年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
用双向电泳分析淡色库蚊卵、二令幼虫、四令幼虫、蛹和成虫蛋白质组成.电泳完毕后,用考马斯亮兰G-250染色,结果以成蚊蛋白质多肽点为最多(116点),其次依次为蛹(101点)、卵(70点)、四令幼虫(53点)、二令幼虫(18点)。它们在不同分子量和不同PH 范围内的分布也不同,但总的来看,在幼体阶段(卵、二、四令幼虫及蛹)多偏低分子量和低PI 值的点,发育至成虫阶段,分布走向全面。 相似文献
32.
S. V. Litvinov T. F. Malivanova Yu. V. Chuev I. N. Kryukova 《Bulletin of experimental biology and medicine》1988,105(4):573-575
All-Union Oncologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Trapeznikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 105, No. 4, pp. 475–477, April, 1988. 相似文献
33.
Enrico Bertino Carolina Bisson Claudio Martano Alessandra Coscia Claudio Fabris Giovanna Monti Tiziana Testa Amedeo Conti 《Pediatric allergy and immunology》2006,17(7):484-488
AIM: A positive correlation between maternal and cord-blood IgE levels is well documented for total IgEs, but not for specific IgEs. The difficulty in detecting specific cord-blood IgEs is due to their low concentrations, which hinder their dosage by low-sensitivity methods. The study aimed to correlate maternal and foetal specific IgEs against individual cow's milk proteins, detected by highly sensitive and specific techniques. METHODS: Cow's milk specific IgE detection was performed by chemiluminescence on 52 specimens of maternal and cord blood after cow's milk protein separation by 1D and 2D gel electrophoresis. Cow's milk protein (CMP) antigens were identified by mass spectrometry techniques. RESULTS: Specific IgEs for CMPs were found in 25/52 (48.1%) of maternal sera and in 19/52 (37%) of cord-blood sera. In order of decreasing frequency, the proteins found were BSA, IgG heavy chain, caseins and, in a single case, b-lactoglobulin. Positive cord-blood sera in all cases corresponded to a positive maternal result, and maternal and foetal immunoreactivity patterns were closely correlated. Moreover, in no case was there a positive cord-blood response with a negative maternal response. CONCLUSION: The study demonstrates a close relationship between maternal and cord-blood specific IgE patterns. The phenomenon observed could provide a model to elucidate the general production method of foetal IgEs, which might only be produced in the presence of both the corresponding maternal IgE and the related allergen. 相似文献
34.
人骨形态发生蛋白-2基因转染脂肪源性间充质干细胞的成骨研究 总被引:1,自引:0,他引:1
目的 探讨人骨形态发生蛋白-2(hBMP-2)基因修饰的人脂肪源性间充质干细胞(ADSCs)的成骨能力及基因转染对ADSCs成骨分化的生物学调控。方法 流式细胞技术鉴定从人脂肪组织中提取的细胞为间充质来源的干细胞。将ADSCs转染hBMP+2基因,免疫沉淀+Western blotting法和酶联免疫吸附试验(ELISA)检测hBMP-2表达,确定hBMP-2表达量及表达稳定性,碱性磷酸酶(ALP)染色、ALP定量测定、钙结节染色及RT—PCR分析hBMP-2基因转染对ADSCs向成骨细胞转化的调控,并将转基因细胞注入裸鼠股部肌内,通过X线及组织学检查观察体内成骨情况。结果 流式细胞术证实从脂肪中提取的细胞为间充质来源的干细胞。转基因后免疫沉淀+Western blotting法和ELISA法显示转染hBMP-2的ADSCs具有较高且稳定的hBMP-2的表达,转染21d后表达量无明显降低。ALP染色、ALP定量测定、钙结节染色及RT—PCR发现转基因ADSCs向成骨细胞方向发生分化。裸鼠肌内注射转基因细胞后2周即显示有异位骨形成,4周明显增多,对照组无骨组织形成。结论 转染hBMP-2基因的ADSCs在持续稳定高表达目的蛋白的同时,自身向成骨细胞发生分化,并在裸鼠体内形成异位骨。因此,ADSCs有望作为新的基因工程种子细胞。 相似文献
35.
Denise K Chou Yinzhi Zhao Song Gao Iih-Nan Chou Paul Toselli Phillip Stone Wande Li 《Toxicological sciences》2007,99(1):267-276
To probe mechanisms of cadmium (Cd) damage to the lung extracellular matrix (ECM), we developed Cd-resistant (CdR) rat lung fibroblasts (RFL6) by incubation with graded concentrations of Cd. CdR cells downregulated lysyl oxidase (LO), a copper (Cu)-dependent enzyme essential for crosslinking of collagen and elastin in the ECM, in conjunction with upregulation of other Cu-binding proteins including Cu,Zn-superoxide dismutase (SOD1), copper chaperone for SOD1 (CCS1), metallothionein (MT), and Menkes P-type ATPase (ATP7A), a Cu transporter in the membrane of the Golgi apparatus, as well as gamma-glutamylcysteine synthetase (gamma-GCS), an enzyme for glutathione biosynthesis. Reduction and loss of cytoplasmic distribution of LO in CdR cells were accompanied by its dislocation with the Menkes P-type ATPase and the endoplasmic reticulum marker. CdR cells displayed a defect in LO catalytic activity but an enhancement in Cu,Zn-SOD catalytic activity consistent with the protein expression levels of these enzymes. Although long-term Cd exposure of cells enhanced the Menkes P-type ATPase protein expression, actually, it reduced Cu-dependent catalytic activity of this enzyme in parallel with the deficiency of LO. The low level of 64Cu bound to the LO fraction and the high level of 64Cu bound to the MT fraction provide direct evidence for limitation of Cu bioavailability for LO existing in the CdR cells. These results suggest that downregulation of LO is linked with upregulation of other Cu-binding proteins and with alteration in Cu homeostasis in the CdR phenotype. 相似文献
36.
Hanako Tsubone Tomoyuki Onishi Tetsuyuki Hayashibara Shizuo Sobue Takashi Ooshima 《Journal of oral pathology & medicine》2002,31(4):239-241
A Japanese girl was referred to Osaka University Dental Hospital for examination of a tooth-like structure that had erupted following spontaneous exfoliation of a natal tooth in the lower left primary central incisor region. The structure had erupted at 6 months of age, and radiographic and clinical examination showed composition of pulp and dentin, but no enamel. On histological examination, the majority of the dentin area had a tubular dentin-like appearance, while the outer area of the root appeared to be composed of an osteodentin-like substance. Most of the dentin was covered by cementum. These findings suggest that the structure had originated from a developing remnant of the extracted natal tooth, which must have remained in the gingival tissues. We termed this calcified structure a residual natal tooth. 相似文献
37.
38.
39.
应用银染技术,对24例结肠腺癌Ⅱ级不典型增生,30例绒毛状腺瘤,14例绒毛状腺瘤Ⅲ级不典型增生和29例高分化管状腺癌进行银染核仁形成区嗜银蛋白(Ag-NORs)定量研究,观察Ag-NORs数量、形态、大小和分布在结肠肿瘤交界性病变中的表达.提示Ag-NORs四项指标定量研究对结肠脉瘤,特别是Ⅲ级不典型增生与绒毛状腺瘤之结肠癌前病变有较好的监测作用. 相似文献
40.
目的 研究骨形态发生蛋白-2(BMP-2)复合明胶羟基磷灰石(HA)涂层多孔钛对兔股骨远端骨缺损的修复作用。方法 以多孔钛粉末为原料,制备三维多孔结构钛载体,然后运用碱热处理+模拟体液等化学方法进行HA涂层,制备具有三维空间结构的HA涂层多孔钛复合材料。36只新西兰兔随机分为实验组及对照组,制备股骨远端圆柱状骨缺损模型,实验组植入复合BMP-2的HA涂层多孔钛材料,对照组单纯植入HA涂层多孔钛材料。分别于6、12、24周取材通过组织学和生物力学分析。结果组织学观察显示于各时间点实验组骨生成均不同程度优于对照组;生物力学测试显示在推出实验中所有样品的剪切应力都随时间增长而增大。其中在6周、12周实验组多孔钛在所有时间点均表现出了比对照组高得多的剪切力(P〈0.05),在24周实验组和对照组差异无统计学意义(P〉0.05)。结论 BMP-2复合明胶HA涂层多孔钛较单纯HA涂层多孔钛植入早期具有更良好的生物相容性、骨传导性及骨诱导性,可成功修复兔股骨远端骨缺损。 相似文献