全文获取类型
收费全文 | 22027篇 |
免费 | 1942篇 |
国内免费 | 1585篇 |
专业分类
耳鼻咽喉 | 128篇 |
儿科学 | 243篇 |
妇产科学 | 199篇 |
基础医学 | 2698篇 |
口腔科学 | 382篇 |
临床医学 | 3174篇 |
内科学 | 3254篇 |
皮肤病学 | 244篇 |
神经病学 | 1136篇 |
特种医学 | 824篇 |
外国民族医学 | 13篇 |
外科学 | 2121篇 |
综合类 | 4009篇 |
现状与发展 | 5篇 |
预防医学 | 1126篇 |
眼科学 | 578篇 |
药学 | 2380篇 |
21篇 | |
中国医学 | 1189篇 |
肿瘤学 | 1830篇 |
出版年
2024年 | 78篇 |
2023年 | 411篇 |
2022年 | 961篇 |
2021年 | 1163篇 |
2020年 | 903篇 |
2019年 | 715篇 |
2018年 | 818篇 |
2017年 | 697篇 |
2016年 | 703篇 |
2015年 | 1076篇 |
2014年 | 1292篇 |
2013年 | 1116篇 |
2012年 | 1624篇 |
2011年 | 1785篇 |
2010年 | 1057篇 |
2009年 | 838篇 |
2008年 | 1079篇 |
2007年 | 1110篇 |
2006年 | 1114篇 |
2005年 | 1070篇 |
2004年 | 704篇 |
2003年 | 633篇 |
2002年 | 554篇 |
2001年 | 493篇 |
2000年 | 512篇 |
1999年 | 524篇 |
1998年 | 343篇 |
1997年 | 332篇 |
1996年 | 239篇 |
1995年 | 229篇 |
1994年 | 243篇 |
1993年 | 134篇 |
1992年 | 137篇 |
1991年 | 135篇 |
1990年 | 138篇 |
1989年 | 107篇 |
1988年 | 110篇 |
1987年 | 88篇 |
1986年 | 64篇 |
1985年 | 65篇 |
1984年 | 24篇 |
1983年 | 15篇 |
1982年 | 20篇 |
1981年 | 21篇 |
1980年 | 11篇 |
1979年 | 15篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1958年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Glucokinase and cytosolic phosphoenolpyruvate carboxykinase (GTP) in the human liver. Regulation of gene expression in cultured hepatocytes. 总被引:3,自引:1,他引:2
下载免费PDF全文
![点击此处可从《The Journal of clinical investigation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P B Iynedjian S Marie A Gjinovci B Genin S P Deng L Buhler P Morel G Mentha 《The Journal of clinical investigation》1995,95(5):1966-1973
Glucokinase and phosphoenolpyruvate carboxykinase are key enzymes of glucose metabolism in the rat liver. The former is considered to be instrumental in regulating glucose hepatic release/uptake according to the glycaemia level, and cytosolic phosphoenolpyruvate carboxykinase is a major flux-generating enzyme for gluconeogenesis. The level of expression of both enzymes and the regulation of their mRNAs in the human liver cell were investigated. Surgical biopsies of liver from patients undergoing partial hepatectomies and parenchymal hepatocytes derived from the biopsies were used to assay glucokinase, hexokinase and phosphoenolpyruvate carboxykinase activities. Hepatocytes were placed in culture and the actions of insulin, glucagon and cAMP on glucokinase and phosphoenolpyruvate carboxykinase mRNAs were studied. The main results are: (a) glucokinase accounts for 95% of the glucose phosphorylation activity of human hepatocytes, although this fact is masked in assays of total liver tissue; (b) glucokinase activity is set at a lower level in human hepatocytes than in rat hepatocytes, and vice-versa for the gluconeogenic enzyme phosphoenolpyruvate carboxykinase; and (c) as previously shown in rat liver, glucokinase and phosphoenolpyruvate carboxykinase mRNAs are regulated in a reciprocal fashion in human hepatocytes, insulin inducing the first enzyme and repressing the latter, whereas glucagon has opposite effects. These data have interesting implications with respect to metabolic regulation and intracellular hormone signaling in the human liver. 相似文献
82.
消炎痛对hCG诱发家兔排卵抑制的形态学研究 总被引:3,自引:0,他引:3
应用非甾体抗炎药消炎痛(20mg/kg)抑制hCG 诱发的家兔排卵,注射后的6、9、12、72小时剖腹观察排卵数,并取材进行透射电镜观察和酶组织化学观察。甾体激素合成酶类的组织化学和颗粒细胞内某些细胞器的电镜立体定量学测定结果表明:消炎痛抑制了排卵,却不影响颗粒细胞向黄体细胞的转变。透射电镜观察表明:在排卵前,实验组和对照组最明显的不同是:实验组的外膜和白膜很少见到胶原溶解现象,且表面上皮细胞内含的致密小体不释放其内容物。结果提示:消炎痛主要作用于排卵前卵泡顶部的成纤维细胞和表面上皮细胞,这可能与其抑制了某些与排卵有关的酶的释放有关。 相似文献
83.
目的 分析膝关节盘状半月板(DLM)损伤患者关节镜术后疼痛的危险因素,并构建列线图预测模型。方法 收集2017年1月至2021年12月行关节镜手术治疗的217例DLM损伤患者临床资料。依照NRS数字分级法评估术侧膝关节及髌周疼痛情况,将患者分为疼痛组(≤4分,n=26)和非疼痛组(≥4分,n=191)。采用受试者工作特征(ROC)曲线分析获取有统计学意义的连续性变量的最佳截断值。采用多因素logistic回归模型分析DLM损伤患者关节镜术后疼痛的危险因素。构建预测DLM损伤患者关节镜术后疼痛的列线图预测模型,采用校正曲线对列线图预测模型进行内部验证和性能评价,决策曲线对列线图预测模型的预测效能进行临床净收益评估。结果 疼痛组患者年龄、关节软骨损伤比例、术后无冷敷比例均高于非疼痛组(P<0.05),术后负重时间早于非疼痛组(P<0.05)。ROC曲线分析显示:年龄、术后负重时间的AUC分别为0.767、0.774;最佳截断值分别为54岁、7 d。年龄(>54岁)、关节软骨损伤(有)、术后负重时间(≤7 d)是DLM损伤患者关节镜术后疼痛的独立危险因素,术后冷敷(有)是D... 相似文献
84.
Image-directed percutaneous biopsies with a biopsy gun 总被引:3,自引:0,他引:3
Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method. 相似文献
85.
The primordial plexiform neuropil is very critical to neocortical development. The pioneer neurons, mainly Cajal-Retzius cells
in the marginal zone, and subplate neurons in the subplate, differentiate from the primordial plexiform neuropil. In this
study, the development of corpus callosum, visual cortex, and subcortical pathways has been observed in C57BL/6 mice with
various methods, such as DiI labeling in vitro and in vivo, DiI and DiA in vitro double labeling, immunocytochemistry, and
in vivo BrdU and Fast Blue labeling. As early as E14, the primordial plexiform neuropil can be found in the telencephalic
wall, and it contains many pioneer neurons. On E15 the primordial plexiform neuropil differentiates into the marginal zone
and the subplate. Cajal-Retzius cells exist in the marginal zone, and subplate neurons are in the subplate. Either Cajal-Retzius
cells or subplate neurons have long projections toward the ganglionic eminence, suggesting that they migrate tangentially
from the ganglionic eminence. Cajal-Retzius cells are involved in radial migration, and subplate neurons participate to guide
pathfinding of subcortical pathways. This study reveals how the pioneer neurons, through radial and tangential migration,
play an important role in neocortical formation and in the pathfinding of the corpus callosum and subcortical pathways. Furthermore,
DiI labeling in vivo has demonstrated the presence of pioneer neurons all along the corpus callosum pathway, especially in
the midline. This suggests that pioneer neurons may also play a role in guiding the pathfinding of the corpus callosum.
Accepted: 31 July 2001 相似文献
86.
87.
探索采用血管透明化技术结合粒子图像测速技术(PIV)来研究搭桥血管内血流流场的可行性.结果显示血管透明化技术能完整地保留搭桥血管段在体内的真实立体几何构形,从而更准确地反应搭桥血管段在体内的血流流场,而PIV能很好地获得血流流场的信息.因此,将血管透明化技术与PIV相结合有可能使我们对旁路搭桥术后血管内膜增生的血流动力学成因进行更深入地研究. 相似文献
88.
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
89.
用银染色法、免疫组织化学及透射电镜技术,对36例人肺的神经内分泌细胞进行了形态学和免疫组织化学观察。提示NE细胞发生了废用性退化,其原因可能与出生前后人肺功能改变有关。 相似文献
90.