全文获取类型
收费全文 | 43122篇 |
免费 | 4112篇 |
国内免费 | 3123篇 |
专业分类
耳鼻咽喉 | 340篇 |
儿科学 | 631篇 |
妇产科学 | 458篇 |
基础医学 | 4098篇 |
口腔科学 | 737篇 |
临床医学 | 5981篇 |
内科学 | 5536篇 |
皮肤病学 | 329篇 |
神经病学 | 1717篇 |
特种医学 | 1439篇 |
外国民族医学 | 17篇 |
外科学 | 3479篇 |
综合类 | 9292篇 |
现状与发展 | 24篇 |
一般理论 | 1篇 |
预防医学 | 3582篇 |
眼科学 | 916篇 |
药学 | 5493篇 |
56篇 | |
中国医学 | 3200篇 |
肿瘤学 | 3031篇 |
出版年
2024年 | 180篇 |
2023年 | 676篇 |
2022年 | 1645篇 |
2021年 | 1987篇 |
2020年 | 1556篇 |
2019年 | 1262篇 |
2018年 | 1256篇 |
2017年 | 1413篇 |
2016年 | 1198篇 |
2015年 | 1945篇 |
2014年 | 2457篇 |
2013年 | 2520篇 |
2012年 | 3770篇 |
2011年 | 3931篇 |
2010年 | 2731篇 |
2009年 | 2313篇 |
2008年 | 2684篇 |
2007年 | 2677篇 |
2006年 | 2520篇 |
2005年 | 2323篇 |
2004年 | 1606篇 |
2003年 | 1514篇 |
2002年 | 1233篇 |
2001年 | 905篇 |
2000年 | 823篇 |
1999年 | 723篇 |
1998年 | 436篇 |
1997年 | 418篇 |
1996年 | 280篇 |
1995年 | 281篇 |
1994年 | 219篇 |
1993年 | 137篇 |
1992年 | 120篇 |
1991年 | 115篇 |
1990年 | 117篇 |
1989年 | 81篇 |
1988年 | 71篇 |
1987年 | 46篇 |
1986年 | 64篇 |
1985年 | 49篇 |
1984年 | 29篇 |
1983年 | 16篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1976年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
21.
Songlin Wang DDS PhD Zhaoju Zou DDS FICD Qiquang Wu DDS Kaihua Sun DDS 《Journal of oral and maxillofacial surgery》1992,50(12):1332-1333
Most cases with recurrent parotitis in childhood (RPC) can be cured before puberty.1–3 A few of them, however, may continue to adulthood.1–4 To distinguish this condition from other types of chronic parotitis in adults, such as chronic obstructive parotitis,5 we suggest that the diagnosis of recurrent parotitis in adults (RPA) be reserved for the cases derived from RPC.6 The pathophysiology and development of RPA is still not well known. To our knowledge, there are few reports of RPA in the literature, especially concerning its histopathology. This report describes a cases of RPA studied with sialography and light and electron microscopy. 相似文献
22.
人工家蚕蛹巴西虫草的毒性研究 总被引:4,自引:0,他引:4
对人工家蚕蛹巴西虫草的毒性进行了研究。结果表明:小鼠和大鼠经口LD50分别为>43.0g/kg和>50g/kg。30天喂养试验中大鼠食欲下降,体重增长减慢;血清胆固醇和血清尿素氮浓度降低,血清总蛋白和血糖无改变;血尿常规无异常;心、肝、牌等脏器系数无改变;肝、肾组织病理学检查未发现明显改变。可认为该产品无明显急性和亚急性毒性。 相似文献
23.
24.
目的 探讨前哨淋巴结活检术(SLNB)应用于外阴癌的可行性.方法 选择2004年10月-2008年4月间于中国医学科学院肿瘤医院接受手术治疗、术中采用SLNB的外阴癌患者21例,其中处于研究前期(即2005年5月前)的11例患者采用染料法识别前哨淋巴结(SLN)、处于研究后期的10例患者采用核素-染料联合法识别SLN,术后行常规病理检查.以病理检查结果为金标准,观察SLNB的检测效果;并观察与SLNB相关的并发症的发生情况.结果 21例患者中,20例(95%)检出SLN,其中8例为单侧腹股沟、12例为双侧腹股沟.20例SLN阳性患者共检出83枚SLN,每例患者平均检出4.2枚(1~9枚),每侧腹股沟平均2.6枚(1~6枚).其中,染料法每例患者平均检出4.4枚、每侧腹股沟平均2.5枚,核素-染料联合法每例患者平均检出3.9枚、每侧腹股沟平均2.7枚,分别比较,差异均无统计学意义(t=0.459,P=0.652;t=-0.421,P=0.717).20例SLN阳性患者腹股沟浅组淋巴结中均检出SLN,其中1例双侧腹股沟深组淋巴结中也检出SLN.20例SLN阳性的患者中,8例(10侧腹股沟)术后病理检查显示腹股沟淋巴结转移,其中7例患者(9侧腹股沟)的转移淋巴结中均包括有SLN、1例(1侧腹股沟)出现假阴性.以SLN识别预测同侧腹股沟淋巴结转移的假阴性率为10%(1/10),阴性预测值为96%(22/23).未发现与SLNB相关的损伤及不良反应.结论 SLNB应用于外阴癌安全、可行,以SLN预测同侧腹股沟淋巴结转移具有较高准确性. 相似文献
25.
新生鼠和成年鼠脑7种微量元素含量的比较 总被引:1,自引:0,他引:1
利用高频电感耦合等离子体原子发射光谱法(ICP-AES)测定Sprunge-Dawley大鼠新生期大脑皮层、海马、小脑、间脑和脑桥等部位的锌、铁、铜、锰、铬、锶、钼等7种微量元素的含量,并与成年动物做了比较。结果表明:(1)新生期大鼠全脑7种微量元素含量的多寡依次为:锌、铁、铬、锶、锰、铜、钼;成年期时钢跃居第四位,总含量低于新生期。(2)脑内不同部位微量元素的含量不同。新生大鼠海马和小脑内多数元素含量高于其他脑区,钼在间脑和海马中含量较高。成年鼠皮层、海马微量元素含量较高,皮层内铜、锶、钼含量最低。 相似文献
26.
视盘血管炎——关于混合型的研讨 总被引:2,自引:0,他引:2
对60例(63眼)视盘血管炎的临床分型进行了探讨,结果表明,除分为Ⅰ、Ⅱ两型外,尚存在混合型,当视盘睫状血管炎性病变波及中央静脉,或两个血管系统同时受炎症侵犯时,即可再现混合型的临床表现,视盘明显水肿,视网膜静脉迂张,散在渗出,出血,动脉狭细。眼底荧光血管造影可见视盘荧光早期充盈明显迟缓,后期渗漏面积〉2.0PD,视网膜循环时间延长,混合型兼有Ⅰ,Ⅱ两型的临床特征,应作为一个独立类型存在,同时观察 相似文献
27.
Abstract We previously demonstrated that epidermal growth factor (EGF) induces a several-fold increase in ornithine decarboxylase (ODC) activity and the steady-state level of ODC mRNA in cultured SV40-transformed human keratinocytes (1). Pretreatment of cell cultures with ultraviolet B (UVB) radiation resulted in a reduction of EGF-induced ODC activity. To determine whether UVB inhibits the accumulation of ODC mRNA by EGF, cells were pretreated with 20 mJ/cm2 UVB or sham-irradiated and then incubated with 100 ng/ml EGF. Northern blot analysis revealed that UVB irradiation entirely blocked the EGF induction of ODC mRNA. Since the binding of EGF to its plasma membrane receptor is the first step in initiating a biological response, the effect of UVB on EGF binding was evaluated. UVB treatment of cultured keratinocytes resulted in an immediate and dose-dependent reduction of EGF binding. Scatchard analysis revealed thai the reduction of EGF binding was due to a 52% decrease in the number of available receptors, from 6.2 × 104/cell to 3.0 × 104/cell. However, UVB decreased the EGF-binding affinity very little (Kd = 0.60 nM in control and Kd=0.75 nM in UVB-treated Z114 cells). In addition, UVB did not alter the rate of EGF internalization. These data suggest that UVB blocks the signal transduction pathway of EGF that is involved in regulation of ODC gene expression. Immunoblot analysis of extracts from irradiated cells showed that UVB induced tyro-sine phosphorylation of EGFR and that the quantity of EGFR protein was unaffected by UVB treatment. Phosphorylation of EGFR may be responsible for decreased binding of EGF to its receptor. 相似文献
28.
29.
A framework for coronary vessels analysis in digital subtracted angiograms is described. This method combines the motion estimation with the frame-to-frame structure detection in a natural way such that they act interactively. The first step consists of the extraction of the vessel centrelines in one image and their organization into meaningful constituents or branches of the coronary arterial tree. The motion is then estimated along the centrelines through a gradient based method. These motion estimates supply an initial positioning of an active contour model (or snake) in the next image. This model adapts itself by changing its shape to accurately fit onto the new centrelines. This process is then reiterated on the subsequent images to depict the dynamic behaviour of all the relevant branches. The main interests of this scheme are: (1) the active models operate locally so a fast detection of the vessels can be performed; (2) the centrelines extraction is fully guided by the confluence of the motion estimation and the contour model; (3) both morphological and kinetic features are provided on a quantitative basis. 相似文献
30.
Preparation and characterization of porous beta-tricalcium phosphate/collagen composites with an integrated structure 总被引:11,自引:0,他引:11
Porous beta-tricalcium phosphate (TCP)/collagen composites with different beta-TCP/collagen weight ratio were prepared. The influences of the preparation conditions on the microstructure of porous composite and the joint status of beta-TCP particles with collagen fibrils were characterized by X-ray diffractometer, scanning electron microscopy and transmission electron microscopy. The results showed: (1) an acid treatment could effectively disassemble collagen fibrils; (2) in the resulting porous composites, beta-TCP particles homogenously existed on the skeleton of the collagen fibril network and bonded tightly to both the fibrils and themselves. The tight bonding formation could be due to the reaction between Ca ions in the particles and carboxyl groups in collagen polypeptide chains and due to the reprecipitation of partially dissolved beta-TCP during synthesis. The tight bonding between beta-TCP particles and collagen fibrils in the composites demonstrated an integrated structure, which was reproducible when beta-TCP/collagen ratio ranged from 2 to 4. Such integrated structure would make significant contributions in reliably tailoring properties of the porous composites by varying beta-TCP content. In addition, the porous composites had large porosity (approximately 95%) and appropriate pore size (approximately 100 microm), showed no negative impact in cytotoxicity assay and complete bone tissue regeneration after 12 weeks in animal test. 相似文献