全文获取类型
收费全文 | 12182篇 |
免费 | 415篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 73篇 |
儿科学 | 276篇 |
妇产科学 | 326篇 |
基础医学 | 1367篇 |
口腔科学 | 451篇 |
临床医学 | 1148篇 |
内科学 | 1900篇 |
皮肤病学 | 189篇 |
神经病学 | 1156篇 |
特种医学 | 267篇 |
外科学 | 930篇 |
综合类 | 114篇 |
预防医学 | 1066篇 |
眼科学 | 183篇 |
药学 | 1720篇 |
中国医学 | 35篇 |
肿瘤学 | 1434篇 |
出版年
2024年 | 62篇 |
2023年 | 803篇 |
2022年 | 559篇 |
2021年 | 877篇 |
2020年 | 1063篇 |
2019年 | 1289篇 |
2018年 | 1240篇 |
2017年 | 816篇 |
2016年 | 576篇 |
2015年 | 564篇 |
2014年 | 1150篇 |
2013年 | 2065篇 |
2012年 | 371篇 |
2011年 | 146篇 |
2010年 | 162篇 |
2009年 | 125篇 |
2008年 | 95篇 |
2007年 | 88篇 |
2006年 | 55篇 |
2005年 | 92篇 |
2004年 | 56篇 |
2003年 | 21篇 |
2002年 | 26篇 |
2001年 | 18篇 |
2000年 | 16篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1985年 | 35篇 |
1984年 | 40篇 |
1983年 | 31篇 |
1982年 | 31篇 |
1981年 | 24篇 |
1980年 | 20篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 6篇 |
1976年 | 15篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
63.
We designed experiments in this study to test the hypothesis suggested by recent purification data that blood basophils comprise two populations of different density, which circulate in numbers characteristic for each human subject. Basophils were separated into two density bands by single step centrifugation on a discontinuous Percoll gradient. Band 1 cells were at the interface between plasma and Percoll of density 1.070 gm/ml. Band 2 cells were at the Percoll 1.070 to 1.080 interface. When the number of band 1 basophils was expressed as a percentage of the total in bands 1 and 2, this relative amount generally remained in a narrow range for blood obtained from the same donor on 3 successive days but differed markedly in different individuals. In a series of leukapheresis experiments, we demonstrated that the percentage of band 1 basophils in postleukapheresis venous blood was strikingly similar to the preleukapheresis value. If basophils that repopulated the leukapheresis-depleted circulation came from the bone marrow, we can conclude that blood levels of basophils in bands 1 and 2 are under physiologic control and that the two types of basophils are released in amounts characteristic for each human subject. Additional evidence for two distinct blood basophil populations was provided by histamine measurements. The histamine content per basophil was consistently higher in cells from band 1 than from band 2, the mean difference between pairs of values for 30 subjects being 0.3 +/- 0.04 pg or about 27% of the band 1 basophil histamine content of 1.1 pg. 相似文献
64.
The Thy-1 antigens or rat brain and thymus have been isolated and chemically characterized, but those of mice have not been identified. Moreover, it is uncertain whether the antigens are glycolipids or glycoproteins. This study with highly purified preparations of gangliosides GM1, 1GD1a, GD1b and GT1b from bovine brain and several ganglioside fractions from mouse brain showed that Thy-1 activity does not reside in gangliosides, but rather in the chloroform-methanol-insoluble residue of brain remaining after extraction of gangliosides. The antigen could be solubilized from this residue with a non-ionic detergent. The antigenic activity of the solubilized preparation was heat-labile but resistant to periodate. The chemical properties of the Thy-1 antigen of mouse brain are discussed. 相似文献
65.
Liposomes could bind and fuse efficiently to human erythrocytes in the presence of HVJ when they contained gangliosides isolated from human erythrocytes. Sialosylparagloboside, which has a terminal sequence of NeuAcα2?3Ga1β1?4GlcNac, has a much higher receptor activity to the virus than GD1a, GD1b, GT1b, and GT1a, all of which contain the terminal sequence of NeuAcα2?3Galβ1?3GalNAc or NeuAcα2?8NeuAcα2?3Galβ1?3GalNAc. The activity of sialosylparagloboside is comparable to that of glycophorin, a major sialoglycoprotein of human erythrocytes, when compared on the basis of the required amount (as sialic acid) of compounds. The high affinity of sialosylparagloboside to the viral HANA protein is also suggested by the finding that it showed high inhibitory activity against HVJ-mediated binding of glycophorin liposomes to erythrocytes. Sialosylparagloboside was also highly susceptible to the viral sialidase, the other biological function of HANA protein. 相似文献
66.
Anti-idiotypic antisera were produced in syngeneic (C57BL/6) mice against a monoclonal anti-Dextran B512 (Dex) antibody (38-13). In radioimmunoassays, anti-idiotypic antibodies were shown to react with the homologous idiotype, while failing to recognize another monoclonal anti-Dex antibody, independently derived from C57BL/6 mice (D-16). Plaque inhibition tests confirmed the specificity of the anti-idiotypic antibodies and revealed that the 38-13 idiotype is expressed by about half of all anti-Dex antibodies produced in C57BL/6, but not in CBA mice. Injection of normal (but not athymic) C57BL/6 mice with low doses of 38-13 monoclonal antibodies, contained culture supernatants or ascitic fluids, resulted in a 10-20 fold increase in the numbers of anti-Dex PFC detected in the spleen 5 days later, the majority of which carried the 38-13 idiotype. 相似文献
67.
68.
69.
《Immunobiology》2022,227(6):152298
PLPPs (Phospholipid phosphatases) are widely expressed in different human tissues, regulate cell signal transduction, and are overexpressed in cancers such as gliomas, pancreatic adenocarcinoma, lung adenocarcinoma, and so on. As a member of the PLPP family, PLPP2 (phospholipid phosphatase 2) plays a vital role in the occurrence and development of breast cancer, but its mechanism is still unclear. Our research found that PLPP2 was overexpressed in breast cancer, and the higher expression level of PLPP2 showed a worse prognosis for breast cancer patients. Further analysis showed that overexpression of PLPP2 affected the expression of CDC34 (cell-division cycle 34), LSM7 (Like-Smith 7), and SGTA (small glutamine-rich tetratricopeptide repeat-containing protein alpha) through EMT (epigenetic-mesenchymal transition) related pathways to promote the occurrence and development of breast cancer. In vitro, silencing PLPP2 significantly reduced the proliferation, invasion, and migration abilities of human breast cancer cells MDA-MB-231. ER+ is a common subtype of breast cancer. Furthermore, we found that the overexpression of PLPP2 was significantly related to the poor prognosis of ER+ breast cancer. These results indicate that PLPP2 has value as a potential therapeutic target for breast cancer, especially for ER+ breast cancer. 相似文献
70.