全文获取类型
收费全文 | 170844篇 |
免费 | 15356篇 |
国内免费 | 7881篇 |
专业分类
耳鼻咽喉 | 2298篇 |
儿科学 | 4043篇 |
妇产科学 | 1846篇 |
基础医学 | 31342篇 |
口腔科学 | 5445篇 |
临床医学 | 13254篇 |
内科学 | 23254篇 |
皮肤病学 | 4449篇 |
神经病学 | 9751篇 |
特种医学 | 3749篇 |
外国民族医学 | 118篇 |
外科学 | 14794篇 |
综合类 | 25882篇 |
现状与发展 | 49篇 |
预防医学 | 4861篇 |
眼科学 | 3538篇 |
药学 | 13028篇 |
31篇 | |
中国医学 | 5136篇 |
肿瘤学 | 27213篇 |
出版年
2024年 | 372篇 |
2023年 | 2479篇 |
2022年 | 4372篇 |
2021年 | 6197篇 |
2020年 | 5460篇 |
2019年 | 5275篇 |
2018年 | 5465篇 |
2017年 | 5777篇 |
2016年 | 6054篇 |
2015年 | 6912篇 |
2014年 | 10017篇 |
2013年 | 11087篇 |
2012年 | 9574篇 |
2011年 | 10765篇 |
2010年 | 8927篇 |
2009年 | 8556篇 |
2008年 | 9015篇 |
2007年 | 9221篇 |
2006年 | 8342篇 |
2005年 | 7706篇 |
2004年 | 6811篇 |
2003年 | 5905篇 |
2002年 | 4886篇 |
2001年 | 4173篇 |
2000年 | 3449篇 |
1999年 | 3100篇 |
1998年 | 2949篇 |
1997年 | 2700篇 |
1996年 | 2410篇 |
1995年 | 2112篇 |
1994年 | 1877篇 |
1993年 | 1557篇 |
1992年 | 1272篇 |
1991年 | 1195篇 |
1990年 | 926篇 |
1989年 | 858篇 |
1988年 | 810篇 |
1987年 | 644篇 |
1986年 | 611篇 |
1985年 | 801篇 |
1984年 | 720篇 |
1983年 | 505篇 |
1982年 | 530篇 |
1981年 | 425篇 |
1980年 | 364篇 |
1979年 | 265篇 |
1978年 | 195篇 |
1977年 | 151篇 |
1976年 | 111篇 |
1975年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
表皮生长因子对牛眼小梁细胞c—fos基因表达的诱导 总被引:4,自引:0,他引:4
目的研究表皮生长因子(epidermalgrowthfactor,EGF)对小梁细胞的作用。方法应用分子杂交技术研究EGF对体外培养的牛眼小梁细胞c-fos基因表达的诱导和3H胸腺核苷酸(3H-thymidineincorparation,3H-TdR)掺入法观察细胞DNA的合成。结果小梁细胞的3H-TdR掺入率随着EGF浓度不同而变化,浓度为20~150ng/ml时,细胞掺入率随浓度增加升高(P<0.01)。与对照组相比,EGF刺激停止生长的小梁细胞0.5小时后,c-fos基因开始表达,1小时后达高峰,至2小时后消失。不同浓度EGF刺激小梁细胞1小时后,c-fos基因表达呈浓度依赖性。结论实验结果表明EGF刺激小梁细胞增殖或进入生长状态,可能与c-fos基因产物的信号传递作用有关。 相似文献
22.
Sarah A. Taylor Jacqueline Benedetti David Schuller Stephen P. Richman Goronwy O. Broun Alexander Hantel 《Investigational new drugs》1993,11(2-3):227-229
Summary Twenty-two patients with recurrent or metastatic squamous cell carcinoma of the head and neck were treated with piroxantrone 150 mg/m2 intravenously every 21 days. There were no objective responses. The 95% upper confidence bound for response is 15%. Primary toxicity was hematologic. 相似文献
23.
A variant of the HL-60 cell line, HL-60/MCSFR4D2, has been found to express twice the amount of PTP1C as compared to the parental HL-60 cell line by immunoblotting and immunoprecipitation. Differentiation of the variant cells after phorbol 12-myristate 13-acetate (PMA) treatment was examined by the appearance of adherence. In 1% fetal calf serum (FCS), 20% of HL-60/MCSFR4D2 cells exhibited adherence after treatment with 0.5 ng/ml PMA for 48 h, 60% exhibited adherence after treatment with 1.0 ng/ml PMA and 80% exhibited adherence after treatment with 5.0 ng/ml PMA, while HL-60 cells exhibited only a slight response. Furthermore, antisense PTP1C oligonucleotides decreased the PMA-induced adherence of HL-60/MCSFR4D2 cells. These results suggest that the high-expression of PTP1C in HL-60 cells may be involved in the enhancement of susceptibility to macrophage-like differentiation by PMA. 相似文献
24.
目的:研究健血升白冲剂对小鼠血液系统的影响。方法:以骨髓细胞计数,白细胞计数和血象为指标,观察健血升白冲剂对正常小鼠和化学及放射损伤小鼠的影响。结果:健血升白冲剂明显增加正常小鼠白细胞计数(P<001),显著改善环磷酰胺诱导小鼠白细胞和骨髓细胞的减少作用(分别为P<005,P<001),并能显著增加60Co放射损伤小鼠骨髓细胞(P<001)和白细胞(P<001)。结论:健血升白冲剂对化学及放射损伤小鼠血液系统有明显的保护及改善作用。是一个有开发价值的药物。 相似文献
25.
BACKGROUND: The responses of mice to the mite allergen Der p 1 have been used to study the mechanisms of allergic sensitization and the development of new types of immunotherapy. Many of the studies require a knowledge of the T cell epitopes, and because Der p 1 is polymorphic, the effect of natural amino acid substitution in the allergen. The intranasal administration of peptides containing T cell epitopes can induce a mucosal tolerance but it is not known if the major activity is limited to stimulatory peptides and if, as found for autoimmunity, some epitopes are not inhibitory. OBJECTIVE: To determine and compare the sequences of Der p 1 which contain stimulatory epitopes for the high responding H-2(b) and H-2(q) mice and the sequences which induce tolerance by intranasal administration of peptides. METHODS: T cell responses of mice immunized with Der p 1 were measured by in vitro T cell stimulation assays so an extensive study of epitope recognition and intranasal tolerance could be made. Synthetic peptides were used to examine the stimulatory and inhibitory ability of all Der p 1 sequences and to map the major H-2(b) epitope in detail. This included the effect of the common polymorphic amino acid 124 substitution found within this epitope. RESULTS: Three and two regions, respectively, were found to contain stimulatory T cell epitopes for H-2(b) and H-2(q) mice. The peptides in these regions were also the most active at inducing intranasal tolerance for the responding haplotype. The correspondence between inhibitory and stimulatory peptides was maintained for the fine mapping of the major H-2(b) epitope. This was found about a core region of 118-126 which was overlapping but separate to a consensus sequence for the binding of endogeneous peptides. Peptides with alanine at the naturally polymorphic residue 124 stimulated and inhibited responses to Der p 1 more effectively, while peptides with the valine 124 variant were immunogenic but poorly cross-reactive. CONCLUSIONS: The intranasal administration of peptides representing each of five epitopes recognized by two strains of mice were able to induce mucosal tolerance and the major tolerizing activity was limited to these epitopes. The position of the core major epitope for C57 mice, which differs from a previously predicted epitope, and its specificity for the natural alanine 124 variant is described. 相似文献
26.
38例非小细胞癌脑转移的综合治疗分析 总被引:1,自引:1,他引:0
目的探讨非小细胞肺癌脑转移的有效治疗方案.方法对38例非小细胞肺癌脑转移患者进行头部、胸部放疗并结合全身化疗的综合治疗.结果近期疗效的有效率为76.3%(29/38).神经精神症状缓解率73.7%(28/38),肺部症状缓解率60.5%(23/38).1年生存率31.5%(12/38),2 a生存率10.5%(4/38).结论合理采用综合治疗可有效提高非小细胞肺癌脑转移患者的生存率. 相似文献
27.
Summary Split or full thickness eyelid defects resulting from tumor destruction or surgical excision present a dilemma for plastic and reconstructive surgeons. Full thickness eyelid replacement requires composite grafting of the skin, together with tarsal support of its substitute and mucosa. The flap described by Fricke in 1829 was used for reconstruction of anterior lamella in six lower eyelid defects. In three of our cases chondromucosal grafts taken from nasal septum were utilized for posterior lamella repair. The results have been satisfactory from a functional and cosmetic standpoint. 相似文献
28.
Unfractionated cytokines have been shown to induce in vitro proliferation of neonatal rat Schwann cells but the nature of the mitogen(s) is not known. A mixture of rabbit antibodies specific for recombinant interleukin-1α (IL-1α) and interleukin-1β (IL-1β) inhibited Schwann cell proliferation induced by unfractionated human cytokines whereas antibodies to interleukin-2 (IL-2) and control IgG did not. However, purified human IL-1 and recombinant human IL-1α or β did not induce Schwann cell proliferation on their own. 相似文献
29.
The distribution in renal tumours of 3-fucosyl-N-acetyl lactosamine has been studied by using the monoclonal antibodies AGF 4.36 and AGF 4.48 and immunoperoxidase methods on tissue sections. Seven of 19 nephroblastomas and 12 of 30 renal cell carcinomas contained the epitope. In nephroblastomas the epitope was found on the terminals of type B tubules in six cases and in one case on the type A or neoplastic tubules. In renal carcinoma the antigen was found on the surface of tumour cells. The results suggest that in kidneys bearing nephroblastomas ureteric bud elements may grow into the tumour from the adjacent kidney. 相似文献
30.
目的 探讨种植受体血管内皮细胞在抗异种血管移植超急排斥反应 (HAR)方面的意义。方法 选用豚鼠→大鼠移植模型 ,先将分离、培养的大鼠动脉内皮细胞种植于去内皮的豚鼠动脉内壁 ,再将此豚鼠动脉植入大鼠体内 ,观察动脉血栓形成时间 ,并采用免疫组化技术检测了 Ig M、C3在移植后豚鼠动脉壁上沉积的情况。结果 已种植大鼠内皮细胞的豚鼠动脉血栓形成时间 (2 0 .3± 4.42 h)较植入大鼠体内的正常豚鼠动脉 (0 .35± 0 .2 84h)以及单纯去内皮豚鼠动脉血栓形成时间 (0 .16 5± 0 .0 77h)显著延长 (P<0 .0 0 1)。免疫组化结果显示 ,植入大鼠体内的正常豚鼠内皮细胞表面有 Ig M和 C3沉积 ,而预先种植大鼠内皮细胞的豚鼠动脉内壁无 Ig M和 C3沉积。结论 在异种供体血管壁上预先种植受者血管内皮细胞 ,可延长移植的异种供体血管通畅时间 ,该技术可能在抗异种血管移植 HAR方面具有重要意义 相似文献