全文获取类型
收费全文 | 130025篇 |
免费 | 11215篇 |
国内免费 | 7697篇 |
专业分类
耳鼻咽喉 | 1279篇 |
儿科学 | 1968篇 |
妇产科学 | 1148篇 |
基础医学 | 12924篇 |
口腔科学 | 2280篇 |
临床医学 | 16292篇 |
内科学 | 16596篇 |
皮肤病学 | 1838篇 |
神经病学 | 5619篇 |
特种医学 | 4908篇 |
外国民族医学 | 30篇 |
外科学 | 11573篇 |
综合类 | 26726篇 |
现状与发展 | 28篇 |
一般理论 | 8篇 |
预防医学 | 12072篇 |
眼科学 | 2735篇 |
药学 | 14234篇 |
113篇 | |
中国医学 | 8125篇 |
肿瘤学 | 8441篇 |
出版年
2024年 | 335篇 |
2023年 | 1324篇 |
2022年 | 3399篇 |
2021年 | 4655篇 |
2020年 | 3693篇 |
2019年 | 3073篇 |
2018年 | 3146篇 |
2017年 | 3395篇 |
2016年 | 3312篇 |
2015年 | 5301篇 |
2014年 | 6871篇 |
2013年 | 7435篇 |
2012年 | 10698篇 |
2011年 | 11263篇 |
2010年 | 8902篇 |
2009年 | 7580篇 |
2008年 | 8736篇 |
2007年 | 8693篇 |
2006年 | 7957篇 |
2005年 | 7118篇 |
2004年 | 5641篇 |
2003年 | 5841篇 |
2002年 | 4784篇 |
2001年 | 3812篇 |
2000年 | 2875篇 |
1999年 | 1995篇 |
1998年 | 1066篇 |
1997年 | 1126篇 |
1996年 | 781篇 |
1995年 | 686篇 |
1994年 | 583篇 |
1993年 | 365篇 |
1992年 | 414篇 |
1991年 | 354篇 |
1990年 | 304篇 |
1989年 | 245篇 |
1988年 | 209篇 |
1987年 | 188篇 |
1986年 | 147篇 |
1985年 | 139篇 |
1984年 | 74篇 |
1983年 | 58篇 |
1982年 | 43篇 |
1981年 | 33篇 |
1980年 | 23篇 |
1979年 | 39篇 |
1978年 | 34篇 |
1976年 | 23篇 |
1973年 | 27篇 |
1970年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
141.
The primary objective was to develop equipment and evaluate protocols for non-invasive assessment of contractile properties of human arm flexors. The research design consisted of a non-randomized control trial, with repeated measures. Data from six males and two females were gathered in a clinical research laboratory. The elbow flexor torque following motor point or direct nerve stimulation was measured in response to single pulses or short trains of electrical pulses. Length--tension relationships were determined; comparative data were obtained at the identified optimal muscle lengths. Twitch waveforms and peak torques following either type of stimulation were reproducible (within 10%). Peak torques following a 4-pulse small interpulse interval stimulation were nearly identical for motor-point activation and direct nerve stimulation (15.2+/- 6.6Nm for motor point stimulation; 14.5 +/- 6.6Nm for nerve stimulation). Average perceived pain indexes associated with 4-pulse stimuli were slightly higher following nerve stimulation (782 for nerve versus 6.23 for motor-point, n=8). A reliable methodology (motor-point stimulation) has been identified to perform stimulated force assessment of human arm flexors. 相似文献
142.
Antitumor immune response by CX3CL1 fractalkine gene transfer depends on both NK and T cells 总被引:6,自引:0,他引:6
Xin H Kikuchi T Andarini S Ohkouchi S Suzuki T Nukiwa T Huqun Hagiwara K Honjo T Saijo Y 《European journal of immunology》2005,35(5):1371-1380
The CX3C chemokine fractalkine (CX3CL1) exists as both a membrane-bound form promoting firm cell-cell adhesion and a soluble form chemoattracting leukocytes expressing its receptor CX3CR1. When adenoviral vector expressing mouse fractalkine (AdFKN) was transduced to the tumor cells, fractalkine was expressed as both membrane-bound form on the tumor cells and soluble form in the supernatant in vitro. Intratumoral injection of AdFKN (1 x 10(9)PFU/tumor) into C26 and B16F10 tumors resulted in marked reduction of tumor growth compared to control (C26: 86.5%, p<0.001; B16F10: 85.5%, p<0.001). Histological examination of tumor tissues revealed abundant infiltration of NK cells, dendritic cells, and CD8(+) T lymphocytes 3 and/or 6 days after treatment with AdFKN. Splenocytes from mice treated by AdFKN developed tumor-specific cytotoxic T cells, and thereby protected from rechallenging with parental tumor cells. Antitumor effects by AdFKN were completely abrogated in both NK cell-depleted mice and CD8(-/-) mice, and partially blocked in CD4(-/-) mice. These data indicated that fractalkine mediates antitumor effects by both NK cell-dependent and T cell-dependent mechanisms. This study suggests that fractalkine can be a suitable candidate for immunogene therapy of cancer because fractalkine induces both innate and adaptive immunity. 相似文献
143.
Five retroelement families, L1 and L2 (long interspersed nuclear element, LINE), Alu and MIR (short interspersed nuclear element, SINE), and LTR (long terminal repeat), comprise almost half of the human genome. This genome-wide analysis on the time-scaled expansion of retroelements sheds light on the chronologically synchronous amplification peaks of each retroelement family in variable heights across human chromosomes. Especially, L1s and LTRs in the highest density on sex chromosomes Xq and Y, respectively, disclose peak activities that are obscured in autosomes. The periods of young L1, Alu, LTR, and old L1 peak activities calibrated based on sequence divergence coincide with the divergence of the three major hominoid divergence as well as early eutherian radiation while the amplification peaks of old MIR and L2 account for the marsupial-placental split. Overall, the peaks of autonomous LINE (young and old L1s and L2s) peaks and non-autonomous SINE (Alus and MIRs) have alternated repeatedly for 150 million years. In addition, a single burst of LTR parallels the Cretaceous-Tertiary (K-T) boundary, an exceptional global event. These findings suggest that the periodic explosive expansions of LINEs and SINEs and an exceptional burst of LTR comprise the genome dynamics underlying the macroevolution of the hominoid primate lineage. 相似文献
144.
We report two cases of lichen planus pigmentosus (LPP) that developed in a unilateral linear pattern. The patients presented with unilateral linear brown macules on the extremities. Skin biopsy showed orthokeratosis, basal hydropic degeneration with scarce lymphohistiocytic infiltrates, and numerous melanophages in both patients. These patients, to the best of our knowledge, are the first cases of LPP presenting with a linear pattern. LPP should be considered in the differential diagnosis of linear hyperpigmented skin lesions. 相似文献
145.
David N Pham Hong Wei Chu Richard J Martin Monica Kraft 《Annals of allergy, asthma & immunology》2003,90(1):72-78
BACKGROUND: Matrix metalloproteinase-9 (MMP-9) is capable of degrading elastin, whereas tissue inhibitor of metalloproteinase-1 (TIMP-1) can inhibit MMP-9 activity. We observed reduced airway tissue elastin volume density in six subjects with nocturnal asthma (NA) as compared with seven subjects with nonnocturnal asthma (NNA) and seven normal controls (NL) when endobronchial biopsies were evaluated morphometrically at 4:00 PM and 4:00 AM. OBJECTIVE: We hypothesized that increased metalloproteinases and decreased tissue inhibitors of metalloproteinases in the airways of subjects with NA may be responsible for reduced elastin volume density. METHODS: Ten additional subjects with NA, 10 subjects with NNA, and 7 normal control subjects underwent bronchoscopy with bronchoalveolar lavage at 4:00 PM and 4:00 AM. Levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 were determined in bronchoalveolar lavage by enzyme-linked immunosorbent assay. RESULTS: There was a fourfold circadian increase in bronchoalveolar lavage levels of MMP-9, and there was a twofold increase in MMP-9:TIMP-1 ratio in NA subjects from 4:00 PM to 4:00 AM. There were no circadian changes in the NNA and NL subjects. At 4:00 AM, MMP-9 levels and the MMP-9:TIMP-1 ratio were highest in NA subjects. At 4:00 PM, no significant group differences were observed. The MMP-9 levels positively correlated with the overnight fall in forced expiratory volume in 1 second and the MMP-9/TIMP-1 ratio negatively correlated with the 4:00 AM % predicted forced expiratory volume in 1 second. CONCLUSIONS: Our results from these two pilot studies suggest that increased MMP-9 and decreased TIMP-1 at night in NA may lead to reduced elastin density. 相似文献
146.
The progressive myoclonus epilepsy of the Lafora type (LD; MIM 254780) is a rare autosomal recessive disorder characterized by epilepsy, myoclonus, progressive neurological deterioration, and the presence of periodic acid-Schiff-positive polyglucosan inclusions (Lafora bodies). Mutations in the EPM2A gene have recently been found to cause LD and about 30 or more mutations have been reported thus far. LD is relatively common in countries of the Mediterranean Basin, the Middle East, India, and Pakistan. Although a few sporadic cases with the typical LD phenotype have also been reported in the Far East including Korea and Japan, a recent effort to find mutations in Japanese LD families was not successful. In the present study, we report two novel mutations in a Korean girl with LD; a 1-bp insertion mutation (c.223insC; G75fsX107) in exon 1 and a missense mutation (c.559A>G; T187A) in exon 3 of the EPM2A gene. To our knowledge, this is the first report of a genetically confirmed case of LD in Koreans and also in the Far East. 相似文献
147.
148.
IFN-γ在沙眼衣原体呼吸道感染中免疫防御机制的探讨 总被引:1,自引:0,他引:1
目的:检测与IFN-γ作用相关的酶吲哚胺2,3二氧化酶(IDO)、诱导性一氧化氮合成酶(iNOS)和NADPH氧化酶(ox)gp91在沙眼衣原体呼吸道感染中的表达及与机体防御的关系,探讨衣原体感染中IFN-γ免疫防御作用的机制.方法:用沙眼衣原体小鼠肺炎株(MoPn)通过鼻腔感染C57BL/6(H-2b)小鼠,用过氧化物酶连接的鼠抗衣原体脂多糖单抗染色HeLa 229细胞,检测衣原体在肺组织的生长;用RT-PCR检测衣原体感染后第7及14天小鼠肺组织IFN-γ、IDO、iNOS和gp91NADPH ox mRNA表达.结果:MoPn呼吸道感染后小鼠肺组织匀浆衣原体活性测定,于感染后第2天,HeLa 229细胞内可见有衣原体包涵体生长,IFU值增高,于感染后第7天IFU达最高水平,以后逐渐下降,至感染后21天基本恢复到基线水平.与未感染的对照组比较,Th1细胞因子IFN-γ于感染后第7天表达显著增高,感染后14天有所降低,但仍维持较高水平;同时衣原体感染可显著诱导与IFN-γ作用相关的三种酶IDO、iNOS和gp91 NADPH ox在小鼠肺组织的表达,感染后第7及14天,IDO,iNOS及gp91 NADPH ox的表达与对照组比较均有显著差异,其中IDO和gp91 NADPH ox于感染后第7天mRNA表达增高显著(P<0.01),14天略有下降(P<0.05).结论:衣原体呼吸道感染诱导Th1细胞因子IFN-γ mRNA高表达,参与宿主对衣原体的清除及机体免疫防御,此作用可能与其相应的酶IDO、iNOS和gp91 NADPH ox表达增高有关. 相似文献
149.
目的 探讨表达中国株HIV 1gp12 0基因的核酸疫苗在小鼠体内的免疫反应。方法 将表达HIV 1gp12 0的核酸疫苗质粒pVAXP经肌肉注射免疫Balb c小鼠 ,检测免疫小鼠脾CD4 +、CD8+T细胞亚群的数量 ,脾特异性CTL杀伤活性和血清抗体滴度。结果 重组质粒pVAXP免疫组小鼠脾CD4 +、CD8+T细胞亚群的数值均比对照组高 (P <0 .0 5 ) ;免疫组脾特异性CTL杀伤活性与对照组相比差异极显著 (P <0 .0 1) ;血清抗体滴度显著高于对照组 (P <0 .0 5 )。结论 表达HIV 1gp12 0基因的核酸疫苗质粒pVAXP能诱导小鼠产生特异性细胞和体液免疫。 相似文献
150.
Large-scale molecular and tissue microarray analysis of mesothelin expression in common human carcinomas 总被引:10,自引:0,他引:10
Frierson HF Moskaluk CA Powell SM Zhang H Cerilli LA Stoler MH Cathro H Hampton GM 《Human pathology》2003,34(6):605-609
The 40-kilodalton processed glycoprotein, mesothelin, is highly expressed in epithelial mesotheliomas and adenocarcinomas of the ovary (serous papillary) and pancreas, but its expression in a large series of other common carcinomas has not been completely explored. In the present study, we used oligonucleotide and tissue microarrays to profile the expression of the mesothelin gene (MSLN) and encoded protein, respectively. Among 150 carcinomas of multiple anatomic sites, we found the highest average expression of MSLN in serous carcinomas of the ovary and adenocarcinomas of the pancreas, consistent with previous reports, as well as measurable but less-striking expression in pulmonary, gastric/esophageal, and colorectal adenocarcinomas. On tissue microarrays containing 621 carcinomas derived from the same and additional sites as those profiled by gene expression, mesothelin immunoreactivity was highest in cancers of the ovary (serous papillary, endometrioid, and undifferentiated) and pancreas, with less frequent staining seen in adenocarcinomas of the endometrium, lung, and stomach/esophagus. Some immunopositivity was observed in 42% of pulmonary adenocarcinomas, including 18% that had >50% of tumor cells that were immunoreactive. Some 14% of breast and 30% of colorectal adenocarcinomas showed immunopositivity, but no case contained >50% tumor cells that were immunoreactive. Mesothelin was either entirely absent or present in <5% of carcinomas of the prostate, bladder/ureter, liver, kidney, and thyroid. Overall, we observed good concordance between the results obtained by oligonucleotide and tissue microarrays. This large study of the MSLN gene and protein expression in common carcinomas provides data for future investigations that evaluate the utility of mesothelin/megakaryocyte potentiating factor as a potential serum tumor marker or target of immunotoxin-based therapy in human cancers. 相似文献