全文获取类型
收费全文 | 152843篇 |
免费 | 15331篇 |
国内免费 | 4903篇 |
专业分类
耳鼻咽喉 | 1364篇 |
儿科学 | 2497篇 |
妇产科学 | 1735篇 |
基础医学 | 29773篇 |
口腔科学 | 3644篇 |
临床医学 | 9713篇 |
内科学 | 23194篇 |
皮肤病学 | 2987篇 |
神经病学 | 14618篇 |
特种医学 | 3640篇 |
外国民族医学 | 42篇 |
外科学 | 12336篇 |
综合类 | 16380篇 |
现状与发展 | 22篇 |
预防医学 | 6142篇 |
眼科学 | 1706篇 |
药学 | 23356篇 |
35篇 | |
中国医学 | 5743篇 |
肿瘤学 | 14150篇 |
出版年
2024年 | 350篇 |
2023年 | 2555篇 |
2022年 | 5276篇 |
2021年 | 6890篇 |
2020年 | 5722篇 |
2019年 | 6220篇 |
2018年 | 6093篇 |
2017年 | 6103篇 |
2016年 | 5578篇 |
2015年 | 6451篇 |
2014年 | 9212篇 |
2013年 | 9966篇 |
2012年 | 8747篇 |
2011年 | 10377篇 |
2010年 | 8281篇 |
2009年 | 8298篇 |
2008年 | 8046篇 |
2007年 | 6971篇 |
2006年 | 6069篇 |
2005年 | 5314篇 |
2004年 | 4656篇 |
2003年 | 4032篇 |
2002年 | 3051篇 |
2001年 | 2540篇 |
2000年 | 2213篇 |
1999年 | 1974篇 |
1998年 | 1896篇 |
1997年 | 1826篇 |
1996年 | 1647篇 |
1995年 | 1593篇 |
1994年 | 1421篇 |
1993年 | 1297篇 |
1992年 | 1037篇 |
1991年 | 926篇 |
1990年 | 828篇 |
1989年 | 695篇 |
1988年 | 641篇 |
1987年 | 616篇 |
1986年 | 719篇 |
1985年 | 1034篇 |
1984年 | 1082篇 |
1983年 | 777篇 |
1982年 | 811篇 |
1981年 | 670篇 |
1980年 | 613篇 |
1979年 | 480篇 |
1978年 | 327篇 |
1977年 | 282篇 |
1976年 | 288篇 |
1975年 | 191篇 |
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
961.
L. K. Chelidze Yu. S. Lebedin E. N. Tsytsikov V. I. Pivnyuk R. G. Vasilov 《Bulletin of experimental biology and medicine》1994,118(4):1126-1128
The effect of recombinant interleukin-4 on the synthesis of immunoglobulins is studied in a culture of mononuclear cells isolated
from peripheral blood of healthy donors and patients with hay fever. It is shown that interleukin-4 stimulates production
of IgE in cells of healthy donors, but not of hay fever patients, and does not affect the synthesis of other isotypes in either
group. At the same time, increased cell proliferation under the influence of interleukin-4 was observed in cultured cells
of both healthy donors and patients.
Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N
o
10, pp. 426–428, October, 1994
Institute of Pulmonology, Ministry of Health, Moscow. (Presented by D. S. Sarkisov, Member of the Russian Academy of Medical
Sciences) 相似文献
962.
Glycoprotein B of bovine herpesvirus type 4: Its phylogenetic relationship to gB equivalents of the herpesviruses 总被引:1,自引:0,他引:1
Michael Goltz Hermann Broll Annette Mankertz Wolfgang Weigelt Hanns Ludwig Hans-Jörg Buhk Kerstin Borchers 《Virus genes》1994,9(1):53-59
In order to estimate the phylogenetic relationship of BHV-4 among the herpesviruses, we have cloned and sequenced its glycoprotein B (gB). The 2.6 kb open reading frame codes for a 874 amino acid long protein. The comparison of its deduced amino acid sequence with those of its counterparts in 19 distinct herpesviruses groups BHV-4 into the -herpesvirinae. The calculation of an evolutionary tree emphasized that BHV-4 is more closely related to herpesvirus saimiri (HVS) than to Epstein-Barr virus (EBV). However, in contrast to EBV and HVS, the gB of BHV-4 contains a putative protease cleavage site and 20 potential N-glycosylation sites. The alignment of the amino acid sequences revealed that 10 cysteine and 7 proline residues, as well as the motifs SPF and GQLG, were completely conserved among the 20 investigated gBs. 相似文献
963.
Inhibition of CD4+ T lymphocyte binding to fibronectin and immune-cell accumulation in inflammatory sites by non-peptidic mimetics of Arg-Gly-Asp. 下载免费PDF全文
R Hershkoviz N Greenspoon Y A Mekori R Hadari R Alon G Kapustina O Lider 《Clinical and experimental immunology》1994,95(2):270-276
The Arg-Gly-Asp (RGD) cell adhesion motif has been demonstrated in various studies to play a pivotal role in leucocyte and platelet interactions with plasma and extracellular matrix (ECM) glycoproteins. The recognition of the RGD sequence is mediated by heterodimeric receptors designated integrins of the beta 1 subfamily, expressed on distinct cell types, including T lymphocytes. We have recently shown that flexible non-peptidic mimetics of RGD, in which the two ionic side groups were separated by a linear spacer of 11 atoms, bound specifically to the platelet integrin alpha 11b beta 3, and inhibited T cell-mediated immune responses. The present study was designed to (i) further characterize the structural requirements for RGD interactions with CD4+ T cells, and (ii) examine the mechanisms by which the RGD mimetics interfere with immune cell reactivity in vivo. We now report that freezing the conformational degrees of freedom in the spacer chain, which fixes the relative orientation of the guanidinium and carboxylate side groups in a favourable manner, results in a higher level of inhibition of T cell binding to immobilized fibronectin, an RGD-containing ECM glycoprotein. In vivo, treatment of mice with relatively low doses of the RGD mimetics, but not the RGD peptide, inhibited the elicitation of an adoptively transferred DTH reaction. This inhibition was achieved by direct impairment of the ability of antigen-primed lymph node cells to migrate and accumulate in inflammatory sites. Hence, we suggest that the design and production of non-peptidic mimetics of RGD offers a novel approach to study defined parameters related to the structure-function requirements of small adhesion epitopes. Furthermore, this approach could be used therapeutically to inhibit pathological processes which depend on RGD recognition. 相似文献
964.
965.
966.
M Jin A Larsson B O Nilsson 《American journal of reproductive immunology (New York, N.Y. : 1989)》1991,26(2):53-57
Sephadex beads were placed carefully in the uterus on days 2 and 3 and left for 6 to 8 h to absorb uterine secretion. The beads were then removed with volatile silicon oil and mounted on small pieces of nitrocellulose paper. Immuno-staining of these bead blots showed they contained the complement components C1q, C3, C4, and C5. We demonstrated that complement component C3 in the uterine secretion could be activated and deposited on model immune complexes, and also that antibody-coated erythrocytes were lysed in utero, that is, a membrane attack complex was produced. Thus, the mouse uterine secretion at the preimplantation stage contains a functionally active complement system. 相似文献
967.
Ultrastructural study of testicular biopsy specimens from 67 adults with primary testicular disorders (Klinefelter's syndrome, XX male syndrome, Del Castillo's syndrome, and cryptorchidism) revealed the following four Leydig cell types: 1) normal or nearly normal Leydig cells with abundant smooth endoplasmic reticulum, mitochondria with tubular cristae, lipid droplets, and Reinke's crystals; 2) abnormally differentiated Leydig cells without either lipid droplets or Reinke's crystals but with altered mitochondria, concentric unfenestrated cisternae of smooth endoplasmic reticulum, and both paracrystalline and filamentous inclusions; 3) multivacuolated Leydig cells containing abundant lipid droplets; and 4) immature Leydig cells with scarce development of the smooth endoplasmic reticulum and mitochondria, and numerous cytoplasmic microfilaments. Abnormally differentiated Leydig cells might represent dysgenetic cells, whereas immature, normal, and vacuolated Leydig cells might represent three progressive stages in the Leydig cell cycle (undifferentiated, mature, and old involuting Leydig cells). An inverse correlation between the proportion of abnormal Leydig cells and testosterone levels was observed in each of these testicular disorders. 相似文献
968.
The instability of membrane markers expressed by human monocytes and macrophages in culture 总被引:2,自引:0,他引:2
Surface markers were tested on freshly isolated human monocytes and following their in vitro maturation to macrophages. The markers tested were HLA-DR antigens, receptors for the Fc of IgG and complement as well as membrane markers defined by monoclonal antibodies. The results revealed a dynamic expression of some of the markers on monocytes which was influenced by several variables. The expression of the markers was modulated by the presence of different sera, by treatment with lymphokines and interferon and following the in vitro maturation of monocytes to macrophages. The most unstable marker was found to be the HLA-DR, which was modulated by all these variables. The 63D3 was affected by different sera and culture supernatant, as well as following the maturation of monocytes to macrophages, but not by lymphokines and interferon. One of the markers, the Mac 120, was found to be relatively stable and did not change significantly following the maturation of monocytes to macrophages. The Fc and complement receptors were also stable in their expression under these conditions, but were probably partially blocked in the presence of human serum. These results indicated that at least some of the heterogeneity related to the monocyte population was probably not due to the occurrence of stable subsets of cells, but rather to reversible changes in marker expression. 相似文献
969.
Immunoregulatory defects of V alpha 24V+ beta 11+ NKT cells in development of Wegener's granulomatosis and relapsing polychondritis 下载免费PDF全文
Takagi D Iwabuchi K Iwabuchi C Nakamaru Y Maguchi S Ohwatari R Furuta Y Fukuda S Joyce S Onoé K 《Clinical and experimental immunology》2004,136(3):591-600
The frequency of either CD4(-)8(-) (double negative; DN) or CD4(+) V alpha 24(+)V beta 11(+) NKT cells, the expression of CD1d and the binding of CD1d-tetramer loaded with alpha-galactosylceramide (alpha-GalCer) to NKT cells were analysed in peripheral blood mononuclear cells (PBMCs) of patients with Wegener's granulomatosis (WG), relapsing polychondritis (RP) and healthy subjects (HS). DN and CD4(+) V alpha 24(+)V beta 11(+) NKT cells as well as CD1d-alpha-GalCer tetramer-positive NKT cells, were significantly decreased in number in both WG and RP patients compared to those from HS. When cytokine profiles were analysed in these PBMCs upon stimulation with phorbol ester and calcium ionophore, CD4(+) T cells from patients with WG and RP exhibited a Th1 bias, whereas CD4(+) NKT cells from WG patients in remission showed a Th2 bias. These findings suggest that NKT cells (especially CD4(+) NKT cells) play a regulatory role in Th1 autoimmunity in patients with WG and RP. The reduction in NKT cell counts appears to be associated with the low responsiveness to alpha-GalCer. The dysfunction of NKT cells to recognize ligands such as alpha-GalCer may also contribute to the defects observed in NKT cells from WG and RP patients. 相似文献
970.
Immunostaining of galectin-3 and CD44v6 using fine-needle aspiration for distinguishing follicular carcinoma from adenoma 总被引:4,自引:0,他引:4
To evaluate the clinical applicability of galectin-3 and CD44 variant 6 (CD44v6) immunostaining in fine-needle aspiration cytology (FNAC) of thyroid follicular tumors, 79 cytological specimens (35 follicular carcinomas and 44 follicular adenomas) were studied. The positive rates of galectin-3 and CD44v6 were 89 and 74% in follicular carcinoma, respectively, and 25 and 30% in follicular adenoma, respectively. There were no significant correlations between the expression of galectin-3 or CD44v6 in follicular carcinoma and characteristics such as capsular invasion, vascular invasion, metastasis, or tumor size. Positive staining of either galectin-3 or CD44v6 resulted in a diagnostic sensitivity of 97% and a specificity of 52% for follicular carcinoma among follicular tumors. Immunostaining of galectin-3 or CD44v6 using cytological specimens can provide independent information on conventional morphological findings of cytology to distinguish follicular carcinoma from adenoma. 相似文献