全文获取类型
收费全文 | 9495篇 |
免费 | 1027篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 259篇 |
妇产科学 | 114篇 |
基础医学 | 1147篇 |
口腔科学 | 544篇 |
临床医学 | 1011篇 |
内科学 | 1688篇 |
皮肤病学 | 141篇 |
神经病学 | 652篇 |
特种医学 | 408篇 |
外科学 | 1050篇 |
综合类 | 404篇 |
一般理论 | 1篇 |
预防医学 | 1323篇 |
眼科学 | 272篇 |
药学 | 862篇 |
中国医学 | 35篇 |
肿瘤学 | 607篇 |
出版年
2021年 | 123篇 |
2020年 | 76篇 |
2019年 | 129篇 |
2018年 | 134篇 |
2017年 | 112篇 |
2016年 | 136篇 |
2015年 | 172篇 |
2014年 | 204篇 |
2013年 | 311篇 |
2012年 | 367篇 |
2011年 | 456篇 |
2010年 | 304篇 |
2009年 | 231篇 |
2008年 | 329篇 |
2007年 | 376篇 |
2006年 | 388篇 |
2005年 | 421篇 |
2004年 | 474篇 |
2003年 | 420篇 |
2002年 | 474篇 |
2001年 | 444篇 |
2000年 | 369篇 |
1999年 | 313篇 |
1998年 | 188篇 |
1997年 | 212篇 |
1996年 | 130篇 |
1995年 | 110篇 |
1994年 | 111篇 |
1993年 | 114篇 |
1992年 | 185篇 |
1991年 | 188篇 |
1990年 | 232篇 |
1989年 | 206篇 |
1988年 | 164篇 |
1987年 | 179篇 |
1986年 | 168篇 |
1985年 | 140篇 |
1984年 | 120篇 |
1983年 | 113篇 |
1982年 | 77篇 |
1981年 | 65篇 |
1980年 | 56篇 |
1979年 | 88篇 |
1978年 | 72篇 |
1977年 | 60篇 |
1976年 | 71篇 |
1975年 | 58篇 |
1974年 | 62篇 |
1973年 | 66篇 |
1970年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Efficacy of SIV/deltaB670 glycoprotein-enriched and glycoprotein-depleted subunit vaccines in protecting against infection and disease in rhesus monkeys 总被引:11,自引:0,他引:11
M Murphey-Corb R C Montelaro M A Miller M West L N Martin B Davison-Fairburn S Ohkawa G B Baskin J Y Zhang G B Miller 《AIDS (London, England)》1991,5(6):655-662
Immunization with an inactivated whole-virus vaccine is highly effective in preventing lentivirus infection. The viral protein(s) essential to the induction of protective responses, however, have not been identified. To define the role of virion components in the induction of protective immunity, we evaluated the efficacy of glycoprotein-enriched and glycoprotein-depleted simian immunodeficiency virus (SIV) subunit vaccines prepared by lentil-lectin affinity chromatography of gradient-purified virions using the immunization and challenge regimen previously found successful with an inactivated whole-virus vaccine. Infection was determined by successful recovery of virus, the induction of SIV-specific antibody responses, and infection of naive recipients by inoculation with lymph-node-derived lymphocytes from the vaccinates. Immunization with the glycoprotein-enriched preparation prevented infection in two out of four monkeys, whereas the glycoprotein-depleted vaccine failed to prevent infection in all four vaccinates tested. However, the glycoprotein-depleted vaccine appeared to moderate the progression of SIV-induced disease compared with non-immunized infected control monkeys inoculated with the same challenge dose. These data suggest that subunit vaccines containing sufficient quantities of viral glycoproteins can protect against SIV infection, whereas subunit vaccines composed predominantly of viral core proteins cannot. The development of effective vaccines against HIV infection should include studies on the optimum presentation of the viral envelope glycoproteins to produce long-term broadly protective immune responses. 相似文献
32.
赖型钩体flaB2与VR1012中的CpG基序分析 总被引:3,自引:0,他引:3
目的:对问号赖型钩端螺旋体(赖型钩体)DNA疫苗[包括内鞭毛蛋白基因(flaB2)和质粒DNA表达载体(VR1012)]的CpG基序(CpG motifs)进行分析,为DNA疫苗免疫机制的阐明和提高DNA疫苗的效能奠定基础。方法:以flaB2与VR1012构建重组DNA的免疫原,对flaB2及VR1012全核苷酸序列进行计算机分析(分类、计数和定位)。结果:CpG的“C”的侧翼为两个嘌呤,“G”的侧翼为两个嘧啶,在flaB2中共3个,分别为GACGCT,GACGTC和GACGCC;在VR1012中共11个,分别为GACGTC1个,GACGCT2个,GACGCC1个,GACGTT1个,GGCGTT2个,GGCGCT2个,GGCGCC1个,AACGCT1个,其中特别重要的TGACGTCA4个和TAACGCCA有1个,位于5'端456-463;509-516;592-599;778-785和486-493;4个TGACGTCA和1个TAACGCCA均位于5'端且相对集中。结论:赖型钩体flaB2与VR1012构成的DNA疫苗含有TGACGTCA等CpG,这些基序又称免疫刺激序列,构成了DNA疫苗中的佐剂。 相似文献
33.
To evaluate the effect of interleukin-8 (IL8) on glomerular basement membrane (GBM) sulfated compounds and albuminuria, we
infused IL8 in 1% bovine serum albumin (BSA) for 5 days into the left renal artery of Holtzman male rats at the rate of 10
μl/h using an osmotic pump. Control rats received 1% BSA. A significant increase in urinary albumin/creatinine ratio was seen
on the last day of IL8 infusion (0.38±0.11, mean ± SEM) when compared with albumin/creatinine ratio prior to infusion (0.19±0.04,
P = 0.04). No significant differences in urinary albumin excretion prior to and after infusion of 1% BSA were observed. On
the last day of infusion, rats were injected with 35sulfate (1.0 mCi/200 g body weight) intraperitoneally and killed after 8 h. Glomeruli were isolated and GBM obtained. After
5 days of IL8 administration, there was a significant increase in 35sulfate uptake by GBM of the infused kidney (76±10 cpm/dry glomerular weight, mean ± SEM) compared with the uptake seen in
the contralateral kidney (53±9, P = 0.05). The in vivo infusion of IL8 increased the 35sulfate uptake by GBM and augmented the urinary albumin/creatinine ratio, suggesting that IL8 may induce albuminuria by altering
the metabolism of the GBM sulfated compounds. This hypothesis needs to be confirmed by studies on glomerular charge selectivity
and GBM anionic sites during the course of the infusion. Moreover, the persistence of the effect needs to be evaluated by
prolonging the infusion for more than 5 days.
Received June 3, 1996; received in revised form and accepted October 18, 1996 相似文献
34.
2,4-二氯胺基酚(DCAP)是83—1除草剂在哺乳动物体内的主要代谢产物。本研究以三种染毒计划观察了DCAP诱发V79细胞的染色体畸变。结果表明:DCAP是一种染色体损伤剂,诱发的畸变主要为染色单体断裂和交换;3h染毒和染毒后培养17h诱发的染色体畸变率最高,20h染毒观察不到染色体畸变,说明以高浓度短期染毒对高细胞毒性化合物的细胞遗传毒性研究可能是较好的染毒方案。 相似文献
35.
随机选择经长期随访证实的滤泡性甲状腺癌和腺瘤各10例,正常甲状腺组织5例作为对照。按Ploton的染色方法和Crocker推荐的计数方法分别计算三组每例各50个细胞的Ag-NOR嗜银颗粒平均数,再算出三组各自的AgNOR均数,经统计学检验三者有极显著性差异。可望成为甲状腺滤泡性肿瘤良恶鉴别的一项辅助指标。 相似文献
36.
37.
S Kumar C J Harrison J Heighway H B Marsden D C West P M Jones 《International journal of cancer. Journal international du cancer》1987,40(4):499-504
A cell line (T3/73) from a Wilms' tumour has been established from a 9 month-old boy with aniridia. The tumour was removed in 1973. On histological examination a diagnosis of Wilms' tumour was made which showed undifferentiated areas, marked tubule formation and abundant striped muscle fibres. The tumour cells, which are fusiform, grew rapidly in culture without the addition of growth factors, and have undergone over 100 passages. Approximately 95% and 5% were positive for desmin and cytokeratin, respectively. The cell doubling time was 28 hr. Cytogenetic studies revealed a karyotype of 46,XY,del(11) (p12::p14). Although the cells stained very intensely with a monoclonal antibody that detects oncogene ras p 21 antigen, Southern blot analysis using c-Ha-ras as a probe failed to reveal an obvious deletion or amplification of either Ha-ras allele. 相似文献
38.
Three patients with symptomatic occlusions of subclavian artery were operated upon by means of carotid subclavian bypass using ipsilateral jugular vein. The indications for this technique include unavailability of saphenous veins or contraindications to use of prosthetics. Late clinical and angiographic followup have revealed satisfactory results and no changes in caliber of vein graft. 相似文献
39.
Summary The devastating neuropathological changes wrought by the intrathecal administration of vincristine are reported, with a detailed account of the widespread lesions in the brain and spinal cord, found in post-mortem light- and electron-microscope studies. 相似文献
40.
2型糖尿病患者载脂蛋白E基因多态性的研究 总被引:2,自引:0,他引:2
目的:探讨中国人2型糖尿病患者载脂蛋白E(apoE)基因多态性及其与血脂和载脂蛋白水平的关系。方法:采用聚合酶链反应-限制性酶切片段长度多态性法,分别对74例2型糖尿病患者及191例血脂、血糖正常且无糖尿病史者的apoE基因型、空腹血脂及载脂蛋白AI、AⅡ、B100、CⅡ、CⅢ及E进行全面分析。结果:2型糖尿病患者的血清甘油三酯(TG)、总胆固醇(TC),低密度脂蛋白胆固醇(LDLC),非高密度脂蛋白胆固醇(nHDLC),载脂蛋白B100、CⅡ、CⅢ、E水平及TG/HDLC比值较对照组显著升高(P<0.01);血清高密度脂蛋白胆固醇(HDLC),apoE/apoCⅢ比值显著降低(P<0.05)。2型糖尿病组与对照组apoE基因频率分布无显著性差异(P>0.05)。携带ε2等位基因组血清TG/HDLC比值较E3/3基因型显著降低;而携带ε4等位基因组血清apoAⅡ水平较E3/3基因型及携带ε2等位基因组显著升高(P<0.001)。结论:2型糖尿病患者apoE基因多态性与血TG/HDLC及apoAⅡ有一定关联。 相似文献