全文获取类型
收费全文 | 5038篇 |
免费 | 235篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 32篇 |
儿科学 | 93篇 |
妇产科学 | 72篇 |
基础医学 | 727篇 |
口腔科学 | 144篇 |
临床医学 | 343篇 |
内科学 | 1226篇 |
皮肤病学 | 124篇 |
神经病学 | 371篇 |
特种医学 | 184篇 |
外科学 | 644篇 |
综合类 | 34篇 |
预防医学 | 200篇 |
眼科学 | 96篇 |
药学 | 523篇 |
中国医学 | 13篇 |
肿瘤学 | 463篇 |
出版年
2023年 | 22篇 |
2022年 | 37篇 |
2021年 | 94篇 |
2020年 | 64篇 |
2019年 | 66篇 |
2018年 | 92篇 |
2017年 | 80篇 |
2016年 | 96篇 |
2015年 | 89篇 |
2014年 | 131篇 |
2013年 | 145篇 |
2012年 | 228篇 |
2011年 | 252篇 |
2010年 | 164篇 |
2009年 | 133篇 |
2008年 | 270篇 |
2007年 | 290篇 |
2006年 | 259篇 |
2005年 | 248篇 |
2004年 | 264篇 |
2003年 | 196篇 |
2002年 | 235篇 |
2001年 | 191篇 |
2000年 | 200篇 |
1999年 | 189篇 |
1998年 | 54篇 |
1997年 | 49篇 |
1996年 | 44篇 |
1995年 | 40篇 |
1994年 | 34篇 |
1992年 | 125篇 |
1991年 | 84篇 |
1990年 | 64篇 |
1989年 | 89篇 |
1988年 | 78篇 |
1987年 | 50篇 |
1986年 | 61篇 |
1985年 | 56篇 |
1984年 | 30篇 |
1983年 | 24篇 |
1980年 | 19篇 |
1979年 | 22篇 |
1975年 | 19篇 |
1974年 | 26篇 |
1973年 | 28篇 |
1972年 | 23篇 |
1971年 | 20篇 |
1970年 | 35篇 |
1969年 | 19篇 |
1967年 | 19篇 |
排序方式: 共有5289条查询结果,搜索用时 109 毫秒
51.
52.
Maeda T Iwasaki A Kawahito S Nakata K Nonaka K Linneweber J Schulte-Eistrup S Takano T Yoshikawa M Sato K Kuwana J Murabayashi S Nosé Y 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2000,46(4):426-430
A silicone membrane hollow fiber oxygenator applicable for use as an extracorporeal membrane oxygenator (ECMO) has been developed in our laboratory. This silicone hollow fiber displays astonishing mechanical stability, is barely compressible or stretchable, and assembles easily while maintaining good gas permeability. The priming volume is 140 cc with a surface area of 0.8 m2. This study evaluated the gas transfer performances and biocompatibility of the oxygenator under ECMO and CPB conditions. In vitro studies that were performed at a blood flow rate of 2 L/min, and revealed O2 and CO2 gas transfer rates of 82.35 +/- 0.56 ml/m2/L/min and 38.72 +/- 2.88 ml/m2/L/min, respectively. The commercially available Kolobow (Avecor 1500) oxygenator was used as the control, and had O2 and CO2 gas transfer rates of 53.8 +/- 0.5 ml/m2/L/min and 24.7 +/- 2.0 ml/m2/L/min. To evaluate blood trauma, Normalized Index of Hemolysis (NIH) was measured according to American Society of Testing and Materials (ASTM) standards. The NIH findings were 0.0112 g/100L at a blood flow of 1 L/min, and 0.0152 g/100L at 5 L/min. Three ex vivo experiments, using a blood flow rate of 1 L/min, were performed with venoarterial bypass, and O2 transfer rate and CO2 transfer rate of the oxygenators were well maintained. This indicates that this preclinical silicone membrane hollow fiber oxygenator has superior efficiency, less blood trauma, and is smaller when compared with the only clinically available Kolobow oxygenator. 相似文献
53.
Lysosome is a primary organelle in B cell receptor-mediated apoptosis: an indispensable role of Syk in lysosomal function 总被引:3,自引:0,他引:3
He J Tohyama Y Yamamoto K Kobayashi M Shi Y Takano T Noda C Tohyama K Yamamura H 《Genes to cells : devoted to molecular & cellular mechanisms》2005,10(1):23-35
To investigate the mechanism of B cell receptor (BCR)-mediated apoptosis, we utilized immature B cell lines, DT40 and WEHI-231. In both cell lines, BCR-crosslinking caused the increase in lysosomal pH with early apoptotic changes characterized by chromatin condensation and phosphatidylserine exposure. This increase was detected in c-Abl-deficient DT40 cells but not in Syk-deficient cells, which corresponded to the fact that the former cells but not the latter revealed BCR-induced apoptosis. In contrast, BCR-crosslinking caused no apparent change in mitochondrial transmembrane potential. Therefore, the lysosomal change might be a primary event in BCR-induced apoptosis in DT40 cells. The increased activity of cathepsin B and apoptosis-preventing effect of a cathepsin inhibitor suggested a significant role of lysosomal enzymes in this apoptosis. By microscopic studies, lysosomes of wild-type DT40 cells fused to BCR-carrying endosomes became enlarged and accumulated one another. In contrast, these changes of lysosomal dynamics did not occur in Syk-deficient cells but transfer of wild-type Syk restored the lysosomal changes and apoptosis. These results demonstrated that the lysosomal change accompanied with the activation of lysosomal enzymes is a primary step in BCR-crosslinking-mediated apoptosis and Syk is responsible for this step through the fusion of BCR-carrying endosomes to lysosomes. 相似文献
54.
Oxidative stress induces the activation of multiple signaling pathways related to various cellular responses. In B cells, Syk has a crucial role in intracellular signal transduction induced by oxidative stress as well as antigen receptor engagement. Treatment of B cells with hydrogen peroxide (H(2)O(2)) induces enzymatic activation of Syk. Syk is essential for Ca(2+) release from intracellular pools through phospholipase C-gamma2 and the activation of c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, and phosphatidylinositol 3-kinase-Akt survival pathway following H(2)O(2) stimulation. Oxidative stress-induced cellular responses in B cells follow different patterns, such as necrosis, apoptosis, and mitotic arrest, according to the intensity of H(2)O(2) stimulation. Syk is involved in the protection of cells from apoptosis and induction of G2/M arrest. Syk leads to the activation of the phosphatidylinositol 3-kinase-Akt survival pathway, thereby enhancing cellular resistance to oxidative stress-induced apoptosis. On the other hand, Syk-dependent phospholipase C-gamma2 activation is required for acceleration toward apoptosis following oxidative stress. These findings suggest that oxidative stress-induced Syk activation triggers the activation of several pathways, such as proapoptotic and survival pathways, and the balance among these various pathways is a key factor in determining the fate of a cell exposed to oxidative stress. 相似文献
55.
Makoto Takano Frances M. Ashcroft 《Pflügers Archiv : European journal of physiology》1996,431(4):625-631
We studied the block of whole-cell ATP-sensitive K+ (KATP) currents in mouse pancreatic-cells produced by external Ba2+. Ba2+ produced a time- and voltage-dependent block of KATP currents, both the rate and extent of the block increasing with hyperpolarization. With 5.6 mM [K+]o, the relationship between the steady-state KATP current and [Ba2+]o, was fit by the Hill equation with aK
d of 12.5 ± 2.8 M at –123 mV and of 0.18 ± 0.02 mM at –62 mV The Hill coefficient (n) was close to 1 at all potentials indicating that binding of a single Ba2+ ion is sufficient to block the channel. When [K+]o was raised to 28 mM the Kd was little changed (12.4 ± 4.1 gM at –123 mV 0.27 ± 0.05 mM at –62 mV) and n was unaffected, suggesting that K+ does not interact with the Ba2+ binding site. The kinetics of Ba2+ block were slow, 10 M Ba2+ blocking the KATP current with a time constant of 20 ms at –123 mV in 28 mM [K+]o. The blocking rate constant was calculated as 1.7 mM–1 ms–1 and the unblocking rate as 0.02 ms–1, at –123 mV The data are discussed in terms of a model in which Ba2+ binds to a site at the external mouth of the channel to inhibit the KATP channel. 相似文献
56.
Hidenori Takahashi Hiroyoshi Takano Akiko Yokoyama Yoshiaki Hara Shigeyuki Kawano Akio Toh-e Tsuneyoshi Kuroiwa 《Current genetics》1995,28(5):484-490
Based on the results of cytological studies, it has been assumed that Cyanidioschyzon merolae does not contain actin genes. However, Southern hybridization of C. merolae cell-nuclear DNA with a yeast actin-gene probe has suggested the presence of an actin gene in the C. merolae genome. In the present study, an actin gene was isolated from a C. merolae genomic library using a yeast actin-gene probe. The C. merolae actin gene has no intron. The predicted actin is composed of 377 amino acids and has an estimated molecular mass of 42003 Da. Southern hybridization indicated that the C. merolae genome contains only one actin gene. This gene is transcribed at a size of 2.4 kb. When Southern hybridization was performed with C. merolae chromosomes separated by pulsed-field gel electrophoresis, a band appeared on unseparated chromosomes XI and XII. A phylogenetic tree based on known eucaryote actin-gene sequences revealed that C. merolae diverged after the division of Protozoa, but before the division of Fungi, Animalia and Chlorophyta. 相似文献
57.
58.
This study describes the unique distribution of Ruffini endings (RE) in the periodontal tissues of the guinea pig teeth with special references to their presence in the enamel-related aspects of the continuously growing incisors and molars. In guinea pig incisors, immunohistochemistry for PGP 9.5 and glia specific S-100 protein revealed a condensed distribution of well-developed RE in the bone-related part of the lingual periodontal ligament as has been reported in many other rodents. In most cases, some RE-like nerve elements characterized by dendritic ramification and rounded terminal Schwann cells were found to be located in the labial, enamel-related regions, where no periodontal ligament-like fiber arrangement was established. In the molar periodontal ligament, well-developed RE-like nerve elements were also distributed in the enamel-related part, but in intimate relation to thick periodontal fiber bundles inserted in the cementum pearls grown on the enamel surface. In some cases, few RE were located in the apical region of the alveolar socket, where no periodontal fiber bundles could be identified. Our data provide the first morphological evidence of the presence of RE-like nerve elements in the enamel-related, fibrous connective tissue of continuously erupting rodent incisors. These data indicate that RE in guinea pig periodontal tissues have variable spatial correlation to the surrounding fibers, implicating their diverse mechanoreceptive properties depending on the anatomical location. 相似文献
59.
11q trisomy detected by fluorescence in situ hybridization 总被引:1,自引:0,他引:1
Takako Takano Yasuko Yamanouchi Shoko Kawashima Masatsune Date Shintaro Hashira Mitsushiro Kida Toshiaki Abe Yutaka Nakahori Yasuo Nakagome 《Clinical genetics》1993,44(6):324-328
Takano T, Yamanouchi Y, Kawashima S, Date M, Hashira S, Kida M, Abe T, Nakahori Y, Nakagome Y. 11q trisomy detected by fluorescence in situ hybridization. Clin Genet 1993: 44: 324–328. © Munksgaard, 1993 A patient with psychomotor developmental delay, multiple minor anomalies, congenital heart disease and left inguinal hernia is reported. His karyotype was 45,X/46,X,+mar (3 : 37 cells), and the marker chromosome was identified as t(Y;11) (q12;q14?) using fluorescence in situ hybridization and fluorescent chromosome painting. He was diagnosed as mosaic for de novo 11q trisomy. 相似文献
60.