全文获取类型
收费全文 | 7129篇 |
免费 | 639篇 |
国内免费 | 249篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 136篇 |
妇产科学 | 65篇 |
基础医学 | 2987篇 |
口腔科学 | 137篇 |
临床医学 | 419篇 |
内科学 | 1101篇 |
皮肤病学 | 161篇 |
神经病学 | 211篇 |
特种医学 | 121篇 |
外科学 | 378篇 |
综合类 | 793篇 |
现状与发展 | 2篇 |
预防医学 | 224篇 |
眼科学 | 36篇 |
药学 | 443篇 |
中国医学 | 117篇 |
肿瘤学 | 657篇 |
出版年
2023年 | 49篇 |
2022年 | 93篇 |
2021年 | 151篇 |
2020年 | 142篇 |
2019年 | 127篇 |
2018年 | 142篇 |
2017年 | 164篇 |
2016年 | 159篇 |
2015年 | 152篇 |
2014年 | 241篇 |
2013年 | 427篇 |
2012年 | 245篇 |
2011年 | 260篇 |
2010年 | 231篇 |
2009年 | 216篇 |
2008年 | 249篇 |
2007年 | 294篇 |
2006年 | 302篇 |
2005年 | 309篇 |
2004年 | 368篇 |
2003年 | 292篇 |
2002年 | 263篇 |
2001年 | 236篇 |
2000年 | 211篇 |
1999年 | 211篇 |
1998年 | 190篇 |
1997年 | 187篇 |
1996年 | 181篇 |
1995年 | 174篇 |
1994年 | 191篇 |
1993年 | 157篇 |
1992年 | 135篇 |
1991年 | 101篇 |
1990年 | 123篇 |
1989年 | 112篇 |
1988年 | 79篇 |
1987年 | 80篇 |
1986年 | 71篇 |
1985年 | 113篇 |
1984年 | 123篇 |
1983年 | 62篇 |
1982年 | 102篇 |
1981年 | 74篇 |
1980年 | 57篇 |
1979年 | 47篇 |
1978年 | 26篇 |
1977年 | 32篇 |
1976年 | 39篇 |
1975年 | 12篇 |
1972年 | 5篇 |
排序方式: 共有8017条查询结果,搜索用时 218 毫秒
81.
Theresa L. Whiteside Sylvia Miescher H. R. MacDonald V. Von Fliedner 《Journal of immunological methods》1986,90(2):221-233
The separation of viable tumor-infiltrating lymphocytes (TIL) from surgical biopsies of human solid tumors was achieved by velocity sedimentation at unit gravity or by discontinuous density gradients. The two methods were adapted to small volumes and cell numbers not exceeding 1 × 108. The recovery, purity and composition of the TIL-enriched fractions were comparable in the two methods. Density gradients were more rapid, simpler and more practical for preparation under sterile conditions of TIL from clinical material than velocity sedimentation. Lymphocytes in the TIL-enriched fractions obtained by either of the methods were poorly responsive to mitogens. This poor responsiveness is a characteristic of the human TIL and seems to be related to effects exerted by tumor cells. 相似文献
82.
以51例晚期肿瘤患者作为研究对象,对其不同来源的肿瘤浸润淋巴细胞(TIL)进行治疗研究,发现肿瘤组织来源的TIL其有效率及一年生存率明显高于胸腹水及转移淋巴结的TAL;其中肿瘤组织的TIL,胸腹水、转移淋巴结的TAL有效率分别为80.9%、40.0%、46.6%;三者治疗肿瘤患者的一年生存率分别为81.0%、46.7%、60.0%;另外发现胸腹水TAL对实质性肿块治疗疗效较低,为40%,其中静脉滴 相似文献
83.
The distribution and dynamics of the cytotoxic T lymphocyte (CTL) response to hepatitis B surface antigen (HBsAg) were studied in mice after intramuscular DNA immunization and after hepatic infection by a recombinant adenovirus that expresses the hepatitis B virus genome (Ad-HBV). CTLs specific for HBsAg accumulate preferentially in the spleen after DNA immunization but are primarily intrahepatic after Ad-HBV infection. The secondary CTL response to Ad-HBV in DNA-primed mice is characterized by rapid depletion of effector CTLs from the spleen, and their expansion in the liver where they cause hepatitis, secrete interferon gamma (IFNγ), and inhibit HBV gene expression. Suppression of HBsAg synthesis is accompanied by disappearance of intrahepatic IFNγ-producing CTLs and their reaccumulation in the spleen. The data suggest a possible explanation for the paucity and functional deficiency of HBV-specific CTLs in the periphery during chronic HBV infection, and that the severity of infection can be worsened by a preexisting CTL response if neutralizing antibody is not also present. 相似文献
84.
Sister chromatid exchange (SCE) was studied in cultured lymphocytes from a limited series of 21 like-sexed twin pairs; 11 monozygotic (MZ) and 10 dizygotic (DZ) pairs. The 18 subjects, who were between 57 and 61 years old, had an SCE mean value () of 8.0 whereas the 24 subjects between 33 and 39 years of age had a mean of 6.8. The difference was statistically significant ( P <0.001). The effect of age appeared to be present in both sexes. No significant difference was found between females (%7.3) and males (%7.5), nor between smokers (%7.3) and non-smokers (%7.4). Drug users had a slightly higher mean (%7.9) than non-users (= 7.0) ( P < 0.05). This trend was found in each age group. The within-pair variance was slightly higher in DZ than in MZ pairs. The difference was not significant. We conclude that genetic factors are probably not a major source of subject variation in SCE mean value. 相似文献
85.
A monoclonal antibody (RH1-38) which blocks multiple systems of cell-mediated cytotoxicity was functionally characterized. RH1-38 specifically blocks, in the absence of complement, natural killer (NK) activity (K562 targets) without any effect on NK-K562 conjugate formation. Kinetic studies suggested that the antibody blocks a step that occurs 30-120 min after effector populations are mixed with target cells. Single-cell cytotoxicity assays in agarose, combined with standard 51Cr release assays and Michaelis-Menten analysis revealed that RH1-38 markedly decreases Vmax and the number of active NK cells, again without any effect on the number of target-binding cells. The maximum recycling capacity was usually decreased, but in some experiments unchanged, in the presence of the monoclonal antibody. RH1-38 inhibited equally well whole peripheral blood mononuclear leukocytes (PBML), Percoll-fractionated lymphocytes enriched for NK activity, and interferon (IFN)-boosted NK activity. PBML exposed to RH1-38 and then washed mediated depressed NK activity which was partially reversed by subsequent treatment with IFN. These studies are most consistent with the hypothesis that RH1-38 inhibits a step late in the NK cytolytic mechanism rather than through an effect on conjugate formation. The primary effect is probably not on the IFN-generating or boosting mechanism, but a secondary effect on IFN-related mechanisms cannot be ruled out. Inhibition through an effect on a small lymphocyte modulator of NK activity is also unlikely but not rigorously excluded. Thus, RH1-38 appears to inhibit NK activity through a direct effect on NK effector cells, probably by interfering with a cell-surface molecule which is important in the expression of NK activity. The companion paper demonstrates that this monoclonal antibody immunoprecipitates a molecule which is very similar or identical to the LFA-1 antigen. Thus, RH1-38 recognizes either a novel epitope on the LFA-1 molecule or alternatively a distinct, functional killer cell surface molecule. The epitope appears to be involved in a late step in the cytolytic mechanism, possibly part of the effector cell lytic machinery. 相似文献
86.
Kozo Ohkusu Ken-Ichi Isobe Hiroyoshi Hidaka Izumi Nakashima 《European journal of immunology》1995,25(11):3180-3186
MRL-lpr mice are severely impaired in the Fas pathway of apoptosis induction. We here evaluate another pathway of apoptosis induction in MRL-lpr mice which is protein kinase C (PKC) dependent. Despite the defect of the Fas pathway, apoptosis developed during culture in vitro in splenic T lymphocytes from MRL-lpr mice more extensively than in T lymphocytes from MRL-+/+ mice. Apoptosis induction in the former cells was then found to be greatly promoted by PKC inhibitor H-7, and partially prevented by PKC activator phorbol 12-myristate 13-acetate (PMA). High sensitivity to H-7, but not to PKA inhibitor HA 1004, of these cells for apoptosis induction was confirmed by detailed time course and dose-dependency experiments of the drug effect. Population analysis showed that both CD4+ T lymphocytes and CD8+ T lymphocytes from MRL-lpr mice were highly sensitive to H-7, whereas CD8+ T lymphocytes, but not CD4+ T lymphocytes, from MRL-+/+ mice were susceptible to the reagent. Interestingly, B220+Thy-1+CD4?CD8? T lymphocytes from MRL-lpr mice were most sensitive to H-7 for apoptosis induction. Correspondingly, the membrane-translocated activated PKC-α level in splenic T lymphocytes from MRL-lpr was more extensively up-regulated by PMA than in splenic T lymphocytes from MRL-+/+. These results suggest that some signal consistently activates PKC in MRL-lpr T lymphocytes, and this event is needed for survival of these cells. On the other hand, CD4+CD8+ thymocytes were deleted by apoptosis in culture with PMA, whether these thymocytes were from MRL-lpr mice or MRL-+/+ mice. This finding suggested that the apoptosis induction pathway linked to PKC activation is intact in CD4+ CD8+ thymocytes from the Fas-defective MRL-lpr mice. We conclude from these results that the PKC-dependent signal pathways for either cell death or cell activation are intact or even accelerated in lpr mice, which could both compensate for the loss of the Fas pathway and promote the generation of autoreactive T lymphocytes. 相似文献
87.
目的 探讨肿瘤患者T淋巴细胞亚群的变化及临床意义。方法 采用流式细胞术检测27例肿瘤患者和25例正常对照组的T淋巴细胞亚群。结果 肿瘤患者CD3^+T细胞、CD4^+T细胞和CD4^+/CD8^+比值明显低于对照组并有统计学意义,而CD8^+T细胞显著高于对照组(P〈0.01)。结论 肿瘤患者的免疫功能下降。流式细胞术对肿瘤患者的免疫功能的检测具有快速、敏感、准确的特点,对于评价疗效、判断预后具有重要价值。 相似文献
88.
目的:检测慢性乙型肝炎患者外周血T细胞表面KIR的表达情况。方法:采用三色流式细胞术检测慢性乙型肝炎患者外周血CD4^+T细胞和CD8^high T细胞表面KIR分子表达,并与正常外周血比较。结果:慢性乙型肝炎患者外周血中CD8^high T细胞KIR表达明显高于对照组CD8^high T细胞。正常外周血CD4^+T细胞几乎不表达KIR,慢性乙型肝炎患者外周血中CD4^+T细胞表达KIR。结论:慢性乙型肝炎患者T细胞表面KIR表达明显增加。 相似文献
89.
Sato T Ishikawa S Akadegawa K Ito T Yurino H Kitabatake M Yoneyama H Matsushima K 《European journal of immunology》2004,34(12):3346-3358
B1 cells have different origin and function from conventional B (B2) cells and are considered to be involved in autoantibody production in the development of autoimmune disease. We found that B1 cells preferentially accumulated in the target organs including thymus in aged BWF1 mice, a murine model for systemic lupus erythematosus, and that B lymphocyte chemoattractant (BLC/CXCL13) expression was increased in the thymus before the onset of lupus nephritis, while stromal cell-derived factor-1 (SDF-1/CXCL12) and secondary lymphoid tissue chemokine (SLC/CCL21) expression remained unchanged. Adhesion molecules such as peripheral node addressin (PNAd), ICAM-1, and VCAM-1 were also expressed on endothelial cells in the enlarged thymic perivascular space (PVS) in aged BWF1 mice. BLC protein and PNAd were co-localized on these high-endothelial-venules-like vessels in enlarged PVS. B1 cells expressed higher level of costimulatory molecules and showed a potent antigen-presenting activity in allogeneic mixed lymphocyte reaction comparable to splenic dendritic cells. Interestingly, B1 cells stimulated proliferation of autologous thymic CD4 T cells in the presence of IL-2. These results indicate that aberrant B1 cell trafficking into the thymus due to ectopic high expression of BLC may result in an activation of self-reactive T cells in the development of murine lupus. 相似文献
90.
Inzhevatkin EV Fomenko EY Slepov EV Savchenko AA 《Bulletin of experimental biology and medicine》2004,138(5):497-500
The pattern of metabolic processes in lymphocytes of mice with Ehrlich ascites carcinoma depended on the stage of tumor growth.Translated from Byulleten Eksperimentalnoi Biologii i Meditsiny, Vol. 138, No. 11, pp. 563–566, November, 2004 相似文献