全文获取类型
收费全文 | 101329篇 |
免费 | 7588篇 |
国内免费 | 3938篇 |
专业分类
耳鼻咽喉 | 310篇 |
儿科学 | 1898篇 |
妇产科学 | 1274篇 |
基础医学 | 17167篇 |
口腔科学 | 1375篇 |
临床医学 | 7712篇 |
内科学 | 20888篇 |
皮肤病学 | 1517篇 |
神经病学 | 4688篇 |
特种医学 | 2072篇 |
外国民族医学 | 19篇 |
外科学 | 5859篇 |
综合类 | 14264篇 |
现状与发展 | 21篇 |
预防医学 | 7665篇 |
眼科学 | 814篇 |
药学 | 13823篇 |
26篇 | |
中国医学 | 5214篇 |
肿瘤学 | 6249篇 |
出版年
2023年 | 1143篇 |
2022年 | 2449篇 |
2021年 | 3167篇 |
2020年 | 3060篇 |
2019年 | 3232篇 |
2018年 | 3118篇 |
2017年 | 3252篇 |
2016年 | 3680篇 |
2015年 | 3914篇 |
2014年 | 6745篇 |
2013年 | 7902篇 |
2012年 | 7154篇 |
2011年 | 7490篇 |
2010年 | 5836篇 |
2009年 | 5488篇 |
2008年 | 5297篇 |
2007年 | 4883篇 |
2006年 | 4447篇 |
2005年 | 3845篇 |
2004年 | 3266篇 |
2003年 | 2740篇 |
2002年 | 2224篇 |
2001年 | 1951篇 |
2000年 | 1556篇 |
1999年 | 1341篇 |
1998年 | 1231篇 |
1997年 | 1071篇 |
1996年 | 885篇 |
1995年 | 901篇 |
1994年 | 772篇 |
1993年 | 641篇 |
1992年 | 575篇 |
1991年 | 468篇 |
1990年 | 469篇 |
1989年 | 381篇 |
1988年 | 330篇 |
1987年 | 298篇 |
1986年 | 239篇 |
1985年 | 637篇 |
1984年 | 723篇 |
1983年 | 552篇 |
1982年 | 593篇 |
1981年 | 489篇 |
1980年 | 441篇 |
1979年 | 384篇 |
1978年 | 298篇 |
1977年 | 235篇 |
1976年 | 257篇 |
1975年 | 234篇 |
1974年 | 205篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Veronique Braud E. Yvonne Jones Andrew McMichael 《European journal of immunology》1997,27(5):1164-1169
Human histocompatibility leukocyte antigen E (HLA-E) and mouse major histocompatibility complex (MHC) class Ib antigen, Qa-1, share the same substitutions at two normally conserved positions 143 and 147, which are likely to affect binding of the C terminus of peptides. Qa-1 is able to bind a peptide derived from the leader sequence of H-2 D and H-2 L molecules. We developed a peptide binding assay in vitro to compare the binding specificity of HLA-E with the mouse MHC class Ib molecule Qa-1. We demonstrate that HLA-E binds, although poorly, the peptide which binds to Qa-1 and that it also binds nonamer signal sequence-derived peptides from human MHC class I molecules. Using alanine and glycine substitutions, we could define primary anchor residues at positions 2 and 9 and secondary anchor residues at position 7 and possibly 3. 相似文献
42.
D J Bowen 《Journal of clinical pathology》2002,55(1):1-18
This review focuses on selected areas that should interest both the scientist and the clinician alike: polymorphisms within the factor VIII and factor IX genes, their linkage, and their ethnic variation; a general assessment of mutations within both genes and a detailed inspection of the molecular pathology of certain mutations to illustrate the diverse cause–effect relations that exist; a summary of current knowledge on molecular aspects of inhibitor production; and an introduction to the new areas of factor VIII and factor IX catabolism. An appendix defining various terms encountered in the molecular genetics of the haemophilias is included, together with an appendix providing accession numbers and locus identification links for accessing gene and sequence information in the international nucleic acid databases. 相似文献
43.
石杉碱甲和乙促进小鼠的空间辨别学习和记忆 总被引:1,自引:0,他引:1
石杉碱甲和乙是从石杉科石杉属植物蛇足石杉[Huperzia scrrata(Thunb.)Trev.]中分得的二个新生物碱。“Y”迷宫实验表明,ip Hup-A 0.075~0.125 mg/kg或Hup-B 0.4~0.8mg/kg,均能明显促进小鼠的空间辨别学习,并能显著预防CO2产生的短时识别障碍,促进记忆保持和记忆再现。ig Hup-A 0.1~0.3 mg/kg或Hup-B 0.8 mg/kg也有促进学习的作用。促进作用Hup-A>Phys>Hup-B。剂量与效应曲线呈倒U型。 相似文献
44.
Active production of anti-human T-lymphotropic virus type I (HTLV-I) IgM antibody in HTLV-I-associated myelopathy 总被引:2,自引:0,他引:2
Kunihiko Nagasato Tatsufumi Nakamura Ohishi Kiyosumi Kohji Shibayama Masakatsu Motomura Ichinose Katsuhiro Mitsuhiro Tsujihata Shigenobu Nagataki 《Journal of neuroimmunology》1991,32(2):105-109
We investigated the presence of anti-human T-lymphotropic virus type I (HTLV-I) IgM in sera and cerebrospinal fluid from patients with HTLV-I-associated myelopathy (HAM) by Western blot analysis. Analyses of 36 serum samples revealed that most patients (31/36; 86.1%) had anti-HTLV-I IgM, whereas only four of 23 (17.4%) HTLV-I carriers had it. In studies of cerebrospinal fluid, anti-HTLV-I IgM was detected in 24 of 36 (66.7%) HAM patients, whereas none was detected in nine HTLV-I carriers. The differences were statistically significant (p less than 0.01). These results suggest that persistent active replication of HTLV-I occurs in the central nervous system as well as in the peripheral blood of HAM patients, and may contribute to the development of HAM. 相似文献
45.
46.
47.
Kathleen Hawker 《Annals of Indian Academy of Neurology》2009,12(4):221-225
B cells have recently been identified as an integral component of the immune system; they play a part in autoimmunity through antigen presentation, antibody secretion, and complement activation. Animal models of multiple sclerosis (MS) suggest that myelin destruction is partly mediated through B cell activation (and plasmablasts). MS patients with evidence of B cell involvement, as compared to those without, tend to have a worse prognosis. Finally, the significant decrease in new gadolinium-enhancing lesions, new T2 lesions, and relapses in MS patients treated with rituximab (a monoclonal antibody against CD20 on B cells) leads us to the conclusion that B cells play an important role in MS and that immune modulation of these cells may ameliorate the disease. This article will explore the role of B cells in MS and the rationale for the development of B cell–targeted therapeutics. MS is an immune-mediated disease that affects over 2 million people worldwide and is the number one cause of disability in young patients. Most therapeutic targets have focused on T cells; however, recently, the focus has shifted to the role of B cells in the pathogenesis of MS and the potential of B cells as a therapeutic target. 相似文献
48.
49.
A. Purohit S. Laffer† C. Metz-Favre A. Verot F. Kricek‡ R. Valenta† G. Pauli 《Clinical and experimental allergy》2005,35(2):186-192
BACKGROUND: Results from several studies indicate that the magnitude of immediate symptoms of type I allergy caused by allergen-induced cross-linking of high-affinity Fc epsilon receptors on effector cells (mast cells and basophils) is not always associated with allergen-specific IgE levels. OBJECTIVE: To investigate the association of results from intradermal skin testing, basophil histamine release and allergen-specific IgE, IgG1-4, IgA and IgM antibody levels in a clinical study performed in birch pollen-allergic patients (n = 18). METHODS: rBet v 1-specific IgEs were measured by quantitative CAP measurements and by using purified Fc epsilon RI-derived alpha-chain to quantify IgE capable of binding to effector cells. Bet v 1-specific IgG subclasses, IgA and IgM levels were measured by ELISA, and basophil histamine release was determined in whole blood samples. Intradermal skin testing was performed with the end-point titration method. RESULTS: Our study demonstrates on the molecular level that the concentrations of allergen-specific IgE antibodies capable of binding to Fc epsilon RI and biological sensitivities are not necessarily associated. A moderate association was found between cutaneous and basophil sensitivity. CONCLUSION: Our results highlight the quantitative discrepancies and limitations of the present diagnostic tools in allergy, even when using a single allergenic molecule. The quantity of allergen-specific serum IgE is only one component of far more complex cellular systems (i.e. basophil-based tests, skin tests) used as indirect diagnostic tests for IgE-mediated allergic sensitivity. 相似文献
50.
E. Wieczerzak E. Jankowska S. Rodziewicz‐Motowido A. Giedo J. giewka Z. Grzonka M. Abrahamson A. Grubb D. Brmme 《Chemical biology & drug design》2005,66(Z1):1-11
Abstract: We have designed and synthesized a new series of azapeptides which act as potential inhibitors of cathepsin B and/or cathepsin K. Their structures are based upon the inhibitory sites of natural cysteine protease inhibitors, cystatins. For the synthesized azapeptides, the equilibrium constants for dissociation of inhibitor–enzyme complex, Ki, were determined. Comparison of these values indicated that all of the azainhibitors act much stronger toward cathepsin B. Z‐Arg‐Leu‐His‐Agly‐Ile‐Val‐OMe ( 7 ) proved to be approximately 500 times more potent for cathepsin B than for cathepsin K. To be able to explain the obtained experimental values we used the molecular dynamics procedures to analyze the interactions between cathepsin B and compound 7 . We also determined the structure of the most potent and selective cathepsin B azainhibitor by means of NMR studies and theoretical calculations. In this report, we describe SAR studies of azapeptide inhibitors indicating the influence of the conformational flexibility of the examined compounds on inhibition of cathepsins B and K. 相似文献