全文获取类型
收费全文 | 56823篇 |
免费 | 5296篇 |
国内免费 | 4323篇 |
专业分类
耳鼻咽喉 | 350篇 |
儿科学 | 485篇 |
妇产科学 | 568篇 |
基础医学 | 6602篇 |
口腔科学 | 1028篇 |
临床医学 | 7859篇 |
内科学 | 8071篇 |
皮肤病学 | 498篇 |
神经病学 | 2843篇 |
特种医学 | 2063篇 |
外国民族医学 | 46篇 |
外科学 | 5403篇 |
综合类 | 10603篇 |
现状与发展 | 19篇 |
一般理论 | 1篇 |
预防医学 | 3751篇 |
眼科学 | 1790篇 |
药学 | 6184篇 |
40篇 | |
中国医学 | 3527篇 |
肿瘤学 | 4711篇 |
出版年
2024年 | 227篇 |
2023年 | 1034篇 |
2022年 | 2534篇 |
2021年 | 3260篇 |
2020年 | 2343篇 |
2019年 | 1891篇 |
2018年 | 2124篇 |
2017年 | 1795篇 |
2016年 | 1753篇 |
2015年 | 2741篇 |
2014年 | 3383篇 |
2013年 | 2789篇 |
2012年 | 4171篇 |
2011年 | 4684篇 |
2010年 | 2704篇 |
2009年 | 2259篇 |
2008年 | 2858篇 |
2007年 | 2869篇 |
2006年 | 2871篇 |
2005年 | 2870篇 |
2004年 | 1916篇 |
2003年 | 1798篇 |
2002年 | 1596篇 |
2001年 | 1289篇 |
2000年 | 1302篇 |
1999年 | 1356篇 |
1998年 | 911篇 |
1997年 | 854篇 |
1996年 | 666篇 |
1995年 | 623篇 |
1994年 | 527篇 |
1993年 | 325篇 |
1992年 | 402篇 |
1991年 | 332篇 |
1990年 | 303篇 |
1989年 | 254篇 |
1988年 | 228篇 |
1987年 | 172篇 |
1986年 | 143篇 |
1985年 | 105篇 |
1984年 | 46篇 |
1983年 | 42篇 |
1982年 | 18篇 |
1981年 | 20篇 |
1980年 | 15篇 |
1979年 | 15篇 |
1977年 | 2篇 |
1973年 | 2篇 |
1935年 | 4篇 |
1910年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Kinetics of the phenotype and function of murine peritoneal macrophages following acute inflammation 总被引:2,自引:0,他引:2
Wu Q Feng Y Yang Y Jingliu Zhou W He P Zhou R Li X Zou J 《Cellular & molecular immunology》2004,1(1):57-62
This study was undertaken to have a better understand for the process and the underlying mechanisms to limitmacrophage activation and population of activated macrophages.A comprehensive kinetics of cytokineproduction was performed in murine peritoneal macrophages recovered from Balb/c mice at various timeduring the course of an intraperitoneal injection with thioglycollate (TG).The expression of cell surfacemolecules such as MHC-Ⅰ,MHC-Ⅱ,B7-1 and B7-2 of these macrophages were also determined by flowcytometry.The present findings of our research suggested that the population of activated macrophages and theactivation of macrophages (including cytokines production and expression of cell surface functional molecules)were strictly controlled during inflammation process.This is one of the important mechanisms to retain the hosthomeostasis.Cellular & Molecular Immunology.2004;1(1):57-62. 相似文献
82.
Bi-directional modulation of T cell-dependent antibody production by prostaglandin E(2). 总被引:1,自引:0,他引:1
Xiaowen He Cornelia M Weyand J?rg J Goronzy Wanyun Zhong John M Stuart 《International immunology》2002,14(1):69-77
T cell-dependent Ig production involves interaction between T cells and B cells. This study evaluated the effects of prostaglandin (PG) E(2) on Ig production in a system in which B cells were co-cultured with autologous CD4(+) T cell clones non-specifically activated by anti-CD3. The effects of PGE(2) on T cell-dependent Ig production differed substantially, depending on the T cells employed. We selected six T cell clones that were able to enhance Ig production (resistant T cell clones) and six T cell clones that inhibited Ig production in the presence of PGE(2) (sensitive T cell clones) for comparison. The resistant T cells produced high levels (>1000 pg/ml) of IL-2 and/or IL-4, and expressed high CD40L, OX40 and CD45RA, and low CD45RO. In contrast, sensitive T cells secreted low IL-2 (<500 pg/ml) and IL-4 (<200 pg/ml), and expressed low CD40, OX40 and CD45RA, and high CD45RO. Adding supernatant derived from resistant T cell clones restored Ig production inhibited by PGE(2), while removing IL-2, IL-4 or IL-10 using specific antibodies inhibited Ig production. In addition, we demonstrated a direct effect of PGE(2) on B cells to enhance Ig production. Consistently, in the presence of resistant T cells, PGE(2) increased B cell proliferation and differentiation. In conclusion, the effects of PGE(2) on Ig production consist of its indirect effects through T cells and its direct effects on B cells. The outcome of the effects can be up-regulatory or down-regulatory, depending whether resistant or sensitive T cells are involved. 相似文献
83.
The protease genes of Bacillus subtilis. 总被引:2,自引:0,他引:2
84.
85.
目的:为选择性脊髓血管造影和椎管内显微外科提供解剖学资料。方法:采用尸体标本30例,于节段性动脉内逐一注入红色乳胶,在完整脊髓上解剖观察。结果:每例脊髓胸腰段的后髓动脉数目5~13支,平均8.4支。后髓动脉起始情况分3型10亚型,其中后髓动脉与前髓动脉由同一肋间后动脉发出仅34支(13.5%)。胸下部及腰部后髓动脉呈典型“发卡”样折曲。后髓动脉平均外径0.37±0.12mm。约1/3标本在T_(11)~L_3间有1支后髓动脉较粗(>0.5mm),它是脊髓后下部血供的主要来源。结论:多数后髓动脉单独起始,较大的后髓动脉应引起注意。 相似文献
86.
Effect of earth's orbital chirality on elementary particles and unification of chiral asymmetries in life on different levels 总被引:4,自引:0,他引:4
Life is chirally asymmetric at all scales from microscopic elementary particles to molecular and macroscopic levels. How these chiral asymmetries in life on different levels are unified remains unanswered. It has been demonstrated that both the biomolecular homochirality and biological rhythms can be caused by the right-handed helical force-field of the Earth's orbital chirality (EOC). Similar to the helical biomolecules (1), it is here suggested that the right-handed EOC force-field could make the right-handed elementary particles more stable than their left-handed enantiomers to result in the symmetry violation of elementary particles, and the EOC could also cause the macroscopic predominant selection of right-handed asymmetries of living objects (e.g. the helical seashells and plants). Our studies indicated that the weak force in weak interaction may only be a form of the EOC force-field at the microscopic particle level, and the chiral asymmetries in life on various levels could be unified by the natural right-handed EOC force-field. Moreover, the chiral and quantum effects, time, mass, rhythms and relativity could also be unified by the interaction of the EOC force-field with chiral motions and structures under certain conditions. 相似文献
87.
With the exception of signs of retraction and withdrawal, there have been few morphological data concerning degenerated neural profiles in adult motor endplates. Here, investigation into the ultrastructure of the soleus motor endplates of adult rats (4 months old) turned up particular axonal degeneration in approximately 3% of the subjects. These axons occur as synaptic debris in the synaptic matrix of the motor endplate, adjacent to thin processes of the perisynaptic cells occupying the outer most layer of the motor endplate and were devoid of basal lamina. They often possessed dense-cored vesicles (50-80 nm). Axonal debris released from Schwann cell processes occurred during the period of acute sciatic neurectomy, when nerve terminals progressively disrupted within the motor endplate associated Schwann cells. Finally, immunohistochemical staining for antibodies to label macrophages (ED1 or ED2) has shown that nerve fiber-associated macrophages are located near the motor endplate. The results suggest that during the course of endplate remodeling, a few parts of the terminal branches are disposed of through spontaneous collapse, subsequent release from the Schwann cell investment, and eventual ingestion by macrophages in the perisynaptic space. 相似文献
88.
Quigley CA Tan JA He B Zhou ZX Mebarki F Morel Y Forest MG Chatelain P Ritzén EM French FS Wilson EM 《Mechanisms of ageing and development》2004,125(10-11):683-695
Partial androgen insensitivity with sex phenotype variation in two unrelated families was associated with missense mutations in the androgen receptor (AR) gene that disrupted the AR NH(2)-terminal/carboxy terminal interaction. Each mutation caused a single amino acid change within the region of the ligand-binding domain that forms activation function 2 (AF2). In one family, the mutation I737T was in alpha helix 4 and in the other F725L was between helices 3 and 4. Neither mutation altered androgen binding as determined by assays of mutant AR in the patient's cultured genital skin fibroblasts or of recombinant mutant receptors transfected into COS cells. In transient cotransfection assays in CV1 cells, transactivation with the AR mutants at low concentrations of DHT was reduced several fold compared with wild-type AR but increased at higher concentrations. Defects in NH(2)-terminal/carboxy terminal interactions were identified in mammalian two hybrid assays. In similar assays, there was reduced binding of the p160 coactivators TIF2/SRC2 and SRC1 to the mutant AR ligand binding domains (LBD). In the family with AR I737T, sex phenotype varied from severely defective masculinization in the proband to a maternal great uncle whose only manifestation of AIS was severe gynecomastia. He was fertile and passed the mutation to two daughters. The proband of the F725L family was also incompletely masculinized but was raised as a male while his half-sibling by a different father was affected more severely and reared as a female. These studies indicate that the function of an AR AF2 mutant in male development can vary greatly depending on the genetic background. 相似文献
89.
Purification of a baculovirus-expressed hepatitis E virus structural protein and utility in an enzyme-linked immunosorbent assay. 总被引:2,自引:0,他引:2 下载免费PDF全文
We report on the purification of the full-length structural protein encoded by open reading frame 2 (ORF-2) of hepatitis E virus. The ORF-2 protein, expressed in Sf9 cells by using a recombinant baculovirus vector system, was successfully purified to homogeneity. Gel electrophoresis of the purified ORF-2 protein showed a single polypeptide of 75 kDa by Coomassie blue staining and by Western blot (immunoblot) analysis. We demonstrated that the partially purified ORF-2 protein could be used successfully in a sensitive and specific enzyme-linked immunosorbent assay for the detection of antibodies to hepatitis E virus. 相似文献
90.
Jin H Kang Y Xiao C Zhu K Ma Y Xie Q Ma J Xie Q He C Yang Z Sun Z Zhang X Chen M Zhang F Wang B 《Viral immunology》2005,18(3):539-548
Prime-boost strategy has been exhibited its potency to enhance immune responses, which would be important to the success to develop a vaccine against the foot-and-mouth disease virus (FMDV). An eukaryotic expression construct encoding the FMDV capsid VP1 protein with a recombinant VP1 protein or a commercial FMDV vaccine were tested in the prime-boost strategy in mice and cattle trials. The levels of induced specific antibodies, T cell proliferations, and DTH activities were significantly higher in the prime-boost groups than in those vaccinated with DNA, protein or FMDV vaccine alone. More importantly, the levels of neutralizing antibodies in the former groups were significantly higher than others and could last for at least four months in cattle trials. This study suggests that the prime-boost strategy significantly improves the effective immunity and may provide a longer protection against FMDV infection. 相似文献