全文获取类型
收费全文 | 6355篇 |
免费 | 288篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 37篇 |
儿科学 | 193篇 |
妇产科学 | 38篇 |
基础医学 | 959篇 |
口腔科学 | 131篇 |
临床医学 | 305篇 |
内科学 | 1744篇 |
皮肤病学 | 91篇 |
神经病学 | 315篇 |
特种医学 | 243篇 |
外科学 | 1132篇 |
综合类 | 21篇 |
预防医学 | 196篇 |
眼科学 | 65篇 |
药学 | 409篇 |
中国医学 | 21篇 |
肿瘤学 | 790篇 |
出版年
2023年 | 28篇 |
2022年 | 88篇 |
2021年 | 151篇 |
2020年 | 79篇 |
2019年 | 115篇 |
2018年 | 127篇 |
2017年 | 105篇 |
2016年 | 148篇 |
2015年 | 155篇 |
2014年 | 219篇 |
2013年 | 259篇 |
2012年 | 399篇 |
2011年 | 430篇 |
2010年 | 251篇 |
2009年 | 243篇 |
2008年 | 425篇 |
2007年 | 434篇 |
2006年 | 409篇 |
2005年 | 430篇 |
2004年 | 405篇 |
2003年 | 388篇 |
2002年 | 387篇 |
2001年 | 67篇 |
2000年 | 64篇 |
1999年 | 65篇 |
1998年 | 107篇 |
1997年 | 92篇 |
1996年 | 67篇 |
1995年 | 58篇 |
1994年 | 55篇 |
1993年 | 57篇 |
1992年 | 38篇 |
1991年 | 48篇 |
1990年 | 37篇 |
1989年 | 29篇 |
1988年 | 29篇 |
1987年 | 21篇 |
1986年 | 18篇 |
1985年 | 19篇 |
1984年 | 16篇 |
1983年 | 18篇 |
1982年 | 12篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1978年 | 10篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1970年 | 6篇 |
1966年 | 5篇 |
排序方式: 共有6690条查询结果,搜索用时 0 毫秒
51.
Summary In vitro CO2 dissociation curves for oxygenated whole blood were determined in 19 healthy male subjects at rest and during submaximal
and maximal bicycle work. Hemoglobin concentration and blood lactate increased with increasing work load and accordingly buffer
value of the whole blood increased while bicarbonate and Base Excess (BE) decreased, resulting in a downward shift of the
CO2 dissociation curve during exercise. Despite the marked increase in buffer values of the blood, the slopes of the CO2 dissociation curves during exercise were found to be about the same as those obtained at rest. It was inferred that the increasing
effect of increased buffer value, on the dissociation slope, was essentially compensated by the decreasing effect of diminished
bicarbonate content. The advantages of this relatively constant CO2 dissociation slope for the indirect measurement of cardiac output by the Fick principle are discussed. 相似文献
52.
Kazuo Nagashima Hisako Endo Koko Sakakibara Yumiko Konishi Ko Miyachi Jau Jinn Wey Yoshiyuki Suzuki Jinichi Onisawa 《Pathology international》1976,26(1):115-132
An autopsy case of a 19-year-old boy who had shown typical gargoyle features, strictly consistent with mucopolysaccharidosis type II (Hunter's syndrome) was reported. Histologically, cytoplasmic vacuolar change was found In hepatocytes, sinusoidal epithelium of spleen, follicular cells of thyroid, Sertoli cells of testis, chromophobe cell of pituitary and generalized fibroblast-like cells including meninges, cardiac valve and periosteum. The vacuoles consisting of membrane-bound structures with flocculus protein-like material and occasional electron dense bodies on electron microscopy, were considered to be the site of mucopolysaccharide deposition by histochemical analysis. Deposition of lipid material consistent with so-called membranous cytoplasmic body was observed in the neurons of central, peripheral and autonomic nervous system. Hepatosplenomegaly could be explained by cytoplasmic deposition, but the cause of cardiomegaly remained further to be studied. Biochemically hepatic mucopolysaccharide was identified as heparan sulfate, while in the kidney dermatan sulfate and heparan sulfate were detected. The correlation between morphology and biochemistry, and between deposition and degeneration was discussed. 相似文献
53.
Arpp,a new homolog of carp,is preferentially expressed in type 1 skeletal muscle fibers and is markedly induced by denervation 总被引:3,自引:0,他引:3
Tsukamoto Y Senda T Nakano T Nakada C Hida T Ishiguro N Kondo G Baba T Sato K Osaki M Mori S Ito H Moriyama M 《Laboratory investigation; a journal of technical methods and pathology》2002,82(5):645-655
In this study, we isolated and characterized a murine counterpart of the human Arpp (hArpp) gene. Sequence analysis revealed that the murine Arpp (mArpp) gene is almost identical to the Ankrd2 gene, which has recently been isolated as a mouse gene induced in stretched skeletal muscle. The mArpp gene encodes a protein of 332 amino acids that contains four well-conserved ankyrin-repeat domains in the central portion of the protein. The amino acid sequence of mArpp protein (mArpp) is highly homologous to that of mouse cardiac-restricted ankyrin-repeat protein (Carp), which is proposed to be a putative genetic marker for cardiac hypertrophy. Immunohistochemical analysis revealed that mArpp is preferentially expressed in type 1 skeletal muscle fibers, and that mArpp is localized in both the nucleus and the sarcomeric I-band of muscle fibers, suggesting that Arpp may function as a nuclear and sarcomeric protein. Furthermore, mArpp was also expressed in neurons of the cerebellum and cerebrum, the islets of Langerhans in the pancreas, and the esophageal epithelium, suggesting that mArpp may play a functional physiologic role in brain, pancreas, and esophagus as well as in type 1 muscle fibers. Interestingly, although mArpp was localized in both nucleus and cytoplasm in neurons, its localization was restricted to nucleus in pancreas and esophagus, suggesting that intracellular localization of mArpp is regulated in a tissue-specific manner. Furthermore, we found that mArpp- and Carp-expression in skeletal muscle were markedly up-regulated after denervation. Although the elevated expression level of Carp was kept only for two weeks after denervation, that of Arpp was kept at least for 4 weeks, suggesting that mArpp and Carp may play distinct functional roles in denervated skeletal muscle. 相似文献
54.
Lee H Tsukiya T Homma A Kamimura T Takewa Y Nishinaka T Tatsumi E Taenaka Y Takano H Kitamura S 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2004,50(3):205-210
Recently, cavitation on the surface of mechanical heart valves has been studied as a cause of fractures occurring in implanted mechanical heart valves. The cause of cavitation in mechanical heart valves was investigated using the 25 mm Medtronic Hall valve and the 23 mm Omnicarbon valve. Closing of these valves in the mitral position was simulated in an electrohydraulic totally artificial heart. Tests were conducted under physiologic pressures at heart rates from 60 to 100 beats per minute with cardiac outputs from 4.8 to 7.7 L/min. The disk closing motion was measured by a laser displacement sensor. A high-speed video camera was used to observe the cavitation bubbles in the mechanical heart valves. The maximum closing velocity of the Omnicarbon valve was faster than that of the Medtronic Hall valve. In both valves, the closing velocity of the leaflet, used as the cavitation threshold, was approximately 1.3-1.5 m/s. In the case of the Medtronic Hall valve, cavitation bubbles were generated by the squeeze flow and by the effects of the venturi and the water hammer. With the Omnicarbon valve, the cavitation bubbles were generated by the squeeze flow and the water hammer. The mechanism leading to the development of cavitation bubbles depended on the valve closing velocity and the valve stop geometry. Most of the cavitation bubbles were observed around the valve stop and were generated by the squeeze flow. 相似文献
55.
Nobuyuki Kimura Takayuki Negishi Yoshiyuki Ishii Shigeru Kyuwa Yasuhiro Yoshikawa 《Neuroscience research》2004,49(3):339-346
In the present study, we investigated how amyloid beta (Abeta) peptides initially affect neuronal cells in primary cerebral cortical cultures from rat and cynomolgus monkey. In these cultures, complicated interactions between glial and neuronal cells occur; moreover, synaptic interactions similar to those observed in vivo also occur between neuronal cells in these cultures. In this study, we applied low concentrations of Abeta to these well-characterized primary cultures to investigate how Abeta initially affects neurons or astroglial cells. In both rat and monkey cortical cultures, treatment with low concentrations of Abeta failed to drastically change or damage of neurons. Abeta treatment, however, significantly activated astrocytes, resulting in increased apolipoprotein E (ApoE) production. Rat astrocytes were more sensitive to Abeta than monkey astrocytes, and responded to Abeta via a different mechanism. In monkey astrocyte cultures, only direct treatment with Abeta increased ApoE production. In rat astrocyte cultures, however, treatment with conditioned media from cortical cultures grown with Abeta increased ApoE production, indicating that some sort of neuron-derived soluble factor(s) was also involved in activating rat astrocytes. These species differences suggest that monkey cortical cultures would be more useful as an in vitro model system to understand the details of how Abeta accumulates in the human brain, since monkeys are phylogenetically more similar to humans. 相似文献
56.
Saruta J Tsukinoki K Sasaguri K Ishii H Yasuda M Osamura YR Watanabe Y Sato S 《Cells, tissues, organs》2005,180(4):237-244
Human saliva chromogranin A (CgA) is clinically promising as a psychological stress marker. However, expression of CgA is poorly understood in humans, although salivary gland localization of CgA in other mammals, such as rodents and horses, has been demonstrated. In the present study, we investigated the expression and localization of CgA in the human submandibular gland (HSG) using various methods. CgA was consistently localized in serous and ductal cells in HSG, as detected by immunohistochemistry and in situhybridization. Reactivity was stronger in serous cells than in ductal cells. In addition, strong immunoreactivity for CgA was observed in the saliva matrix of ductal cavities. Western blotting gave one significant immunoreactive band of 68 kDa in the adrenal gland, HSG and saliva. Finally, CgA was detected in secretory granules of serous and ductal cells by immunoelectron microscopy. In conclusion, CgA in humans is produced by HSG and secreted into saliva. 相似文献
57.
Nishiyama M Hayashi S Futsukaichi Y Suehisa E Kurata Y 《Rinsho byori. The Japanese journal of clinical pathology》2004,52(2):103-108
We measured platelet counts in 95 patients with hematological disorders accompanied by thrombocytopenia (platelet counts < 5.0 x 10(4)/microliter) including 35 patients with severe thrombocytopenia(platelet counts < 2.0 x 10(4)/microliter). We used four methods based on different principles and compared the results, i.e., the flow cytometric method (BEADS method) utilizing platelet-specific monoclonal antibody (SZ2, antiGPIb) in conjunction with fluorescent reference beads (Flow-Count Fluorospheres), manual hemocytometry, and two automated blood cell counters, the NE-8000 (impedance method) and the Technicon H-2 (optical method). The BEADS method was superior to the other methods in linearity of serial dilutions, and the coefficient variations of the BEADS method(2.5-5.2%) were superior to the other methods. The platelet counts measured by the automated blood cell counters were higher(0.6-0.9 x 10(4)/microliter) than those by the BEADS method and manual hemocytometry. Furthermore, the BEADS method was able to measure accurate platelet counts in samples containing red blood cell fragments. The BEADS method may be an accurate and useful method for measuring samples with severe thrombocytopenia, and, especially, samples containing red blood cell fragments. 相似文献
58.
Xiaoyan Tang Sadaaki Hori R. Yoshiyuki Osamura Yutaka Tsutsumi 《Pathology international》1995,45(1):34-44
Extensive immunohistochemical analyses of the hyperplastic human palatine tonsil disclosed variegated B cell phenotypes on the lymphoid cells among the crypt epithelium. The reticular epithelial network was evident by cytokeratin immunostaining. The reticular epithelium near the crypt Iumen was positive for Iysozyme. Secretory component was negative, while HLA-DR was frequently expressed. Intramucosal small Iymphocytes, densely distributed in the Iuminal side, consisted mainly of B cells expressing CD19, CD20, CD21, CD22, CD45R, CD74, DBB42, HLA-DR, HLA-DQ, bcl-2 protein and surface lgM. Some B cells revealed mantle zone phenotypes (surface IgD+, CD5+, CD24+, DBA44+, CD10- -, DNA7- -). Cells of germinocyte phenotype (CD10+, DNA7+) were sparsely seen. A good number of intramucosal lymphoid cells were further labeled for CD11b, a phenotype of so-called B-1 cells. Plasma cells were clustered within the basal half. IgG was their major immunoglobulin class, followed by IgA, IgM and lgD classes. A smaller number of T cells (CD2+, CD3+, CD5+, CD45RO+, TCR αβ+) were identified among the epithelium. CD4+ cells predominated over CD8+ cells. TCR γΔ + cells were rare. Macrophages (CD68+), dendritic histio-cytes (S-100 protein+, CD1+), and natural killer cells (CD16+ or CD57+) were also dispersed. Another unique feature of this lymphoepithelial complex was the existence of HLA-DR intramucosal microvasculature, where lymphocyte recirculation was suggested. Proliferating cell nuclear antigen was detected commonly in the epithelial cells but rarely in the lymphoid cells. Possible lymphoepithelial interactions and morphologic similarities to the thymic medulla are discussed. 相似文献
59.
Favorable efficacy of long-term lamivudine therapy in patients with chronic hepatitis B: an 8-year follow-up study 总被引:7,自引:0,他引:7
Akuta N Suzuki F Suzuki Y Sezaki H Hosaka T Someya T Kobayashi M Saitoh S Arase Y Ikeda K Kobayashi M Kumada H 《Journal of medical virology》2005,75(4):491-498
The long-term efficacy of lamivudine therapy in patients with hepatitis B virus (HBV) infection is still not clear. In this study, 20 non-cirrhotic Japanese patients infected with HBV received lamivudine therapy for more than 1 year and were followed for a median period of 8.5 years (range, 6.7-8.7 years). The rates of HBe antigen (HbeAg) negative, HBV-DNA undetectable, and alanine aminotransferase (ALT) normal level at the start of lamivudine were 55%, 25%, and 20% and 85%, 80%, and were 80%, respectively, at the last visit, including patients who received additional treatment. The values at the last visit tended to and were significantly higher than those at the start. The values improved at the last visit regardless of the emergence of YMDD motif mutant and continuation of lamivudine. YMDD mutant and biochemical relapse with mutant virus (breakthrough hepatitis) appeared in 65% and 45% during follow-up, respectively, but severe breakthrough hepatitis occurred in only 5%. Furthermore, 80% of patients who received additional treatment for breakthrough hepatitis, regardless of continuation of lamivudine, were ALT normal level at the last visit, in contrast to 25% untreated. HBsAg clearance occurred in two patients of the discontinuous lamivudine group with non-vertical transmission, who were relatively young. One was infected with HBV genotype C with breakthrough hepatitis and the other had no YMDD mutant and was infected with genotype D, a rare type in Japan. None developed cirrhosis or hepatocellular carcinoma (HCC) during follow-up. Our results suggest that long-term lamivudine therapy improves long-term prognosis, especially when additional treatment for breakthrough hepatitis is used. 相似文献
60.
Tetsuya Kawashima Yoshiyuki Yokota Mitsuhiro Yokoyama Hiroshi Itoh 《Pathology international》1993,43(6):304-312
The pathomorphologic features of hypertrophic cardiomyopathy simulating dilated cardiomyopathy in the late stage (HCM-DCM) were compared with those of ordinary hypertrophic cardiomyopathy (HCM). Seven autopsied hearts with HCM-DCM and 11 with HCM were assessed quantitatively using an image analyzer. Unlike HCM, significant left ventricular enlargement and wall thinning were observed in HCM-DCM, and the percentage areas of massive fibrosis and disarray were significantly greater. In HCM-DCM, the disarray was distributed diffusely, whereas massive fibrosis was distributed more intensively in the ventricular septum and anterior wall than in the lateral and posterior wall. Narrowing of intramyocardial small arteries was observed more frequently in HCM-DCM, especially in the ventricular septum and anterior wall, than in HCM. These results suggest that the enlargement and wall thinning of the left ventricle in HCM-DCM are attributable to non-uniform progression of massive fibrosis, which is closely related to small-arterial lesions. 相似文献