全文获取类型
收费全文 | 41157篇 |
免费 | 2973篇 |
国内免费 | 2019篇 |
专业分类
耳鼻咽喉 | 468篇 |
儿科学 | 527篇 |
妇产科学 | 560篇 |
基础医学 | 5794篇 |
口腔科学 | 751篇 |
临床医学 | 4757篇 |
内科学 | 7426篇 |
皮肤病学 | 898篇 |
神经病学 | 2450篇 |
特种医学 | 2018篇 |
外国民族医学 | 15篇 |
外科学 | 4720篇 |
综合类 | 3561篇 |
现状与发展 | 6篇 |
一般理论 | 7篇 |
预防医学 | 2140篇 |
眼科学 | 831篇 |
药学 | 4514篇 |
13篇 | |
中国医学 | 1316篇 |
肿瘤学 | 3377篇 |
出版年
2024年 | 72篇 |
2023年 | 444篇 |
2022年 | 1248篇 |
2021年 | 1683篇 |
2020年 | 1119篇 |
2019年 | 1146篇 |
2018年 | 1361篇 |
2017年 | 1148篇 |
2016年 | 1317篇 |
2015年 | 1874篇 |
2014年 | 2328篇 |
2013年 | 2214篇 |
2012年 | 3215篇 |
2011年 | 3285篇 |
2010年 | 2026篇 |
2009年 | 1661篇 |
2008年 | 2185篇 |
2007年 | 2126篇 |
2006年 | 2020篇 |
2005年 | 2010篇 |
2004年 | 1358篇 |
2003年 | 1218篇 |
2002年 | 1037篇 |
2001年 | 767篇 |
2000年 | 849篇 |
1999年 | 827篇 |
1998年 | 554篇 |
1997年 | 574篇 |
1996年 | 477篇 |
1995年 | 417篇 |
1994年 | 335篇 |
1993年 | 263篇 |
1992年 | 376篇 |
1991年 | 299篇 |
1990年 | 297篇 |
1989年 | 275篇 |
1988年 | 236篇 |
1987年 | 205篇 |
1986年 | 181篇 |
1985年 | 171篇 |
1984年 | 71篇 |
1983年 | 77篇 |
1982年 | 36篇 |
1981年 | 44篇 |
1979年 | 36篇 |
1958年 | 63篇 |
1957年 | 61篇 |
1956年 | 59篇 |
1955年 | 52篇 |
1954年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Okamoto T Jeong SY Takahashi Y Baughman KW Ogata K Goto J Kanazawa I 《International journal of molecular medicine》2001,8(4):413-416
Calcium channel blocker is useful for a variety of purposes and is effective for preventing hepatitis elicited by different inducers, suggesting its possible clinical application for treating hepatitis. The alpha1-subunit of the dihydropyridine-sensitive L-type calcium channel is a target of calcium channel blocker. For clinical application of calcium channel blocker, it is important to analyze the expression of the L-type calcium channel in the liver. However, the subtype of the L-type calcium channel alpha1-subunit expressed in the liver was not known. In the present study, the alpha1-subunit of the calcium channel expressed in human liver was systematically analyzed. The alpha1D subunit of the dihydropyridine-sensitive L-type voltage gated calcium channel is expressed relatively strongly in the liver and may play an important role in the liver. 相似文献
52.
The effects of different molecular weights of hyaluronic acid (HA), a major component of extracellular matrix, on gap junctional intercellular communication (GJIC) in normal human dermal fibroblasts (NHDF cells) were investigated. NHDF cells were cultured for 4 days with different molecular weights of HA and then the extent of GJIC was assessed by the scrape-loading dye transfer method, using Lucifer yellow. The area of dye transfer was greater in the dishes coated with HA than in those to which HA was added. Thus, NHDF cells cultured on surfaces coated with high molecular weight (HMW) HA (MW, 800 kDa) showed greatly enhanced GJIC. Furthermore, another aim of this study was to evaluate the effects of different molecular weights of HA on the production of FGF-2 and KGF, because both are important cytokines produced by NHDF cells. When FGF-2 and KGF cultured levels of cell extracts and media were determined by ELISA, both levels were significantly enhanced when cells were grown on plates coated with HMW HA. This finding indicated that the function of gap junction channels in NHDF cells grown on plates coated with HMW HA may promote the biosynthesis of growth factors such as FGF-2 and KGF. 相似文献
53.
一种可生物降解温度敏感型聚乙二醇-聚己内酯-聚乙二醇水凝胶的合成和表征 总被引:1,自引:0,他引:1
合成了一系列分子量较低的聚乙二醇.聚己内酯-聚乙二醇(Poly(ethylene glycol)-Polycaprolactone-Poly(ethylene glycol),PEG-PCL—PEG)三嵌段共聚物。分别采用FTIR和1H—NMR对其结构进行了表征。所合成的PEG-PCL-PEG共聚物具有良好的水溶性,当水溶液浓度高于临界凝胶浓度(Critical gel concentration,CGC)时,随着温度的变化聚合物水溶液会呈现特有的凝胶-溶胶转变。研究了共聚物亲水疏水链段的比例和长度,以及热历史等对凝胶-溶胶转变行为的影响。通过调节上述条件,可以在一定程度上拓宽凝胶-溶胶转变温度范围,有助于PEG—PCL-PEG水凝胶在可注射药物控制释放系统等方面的应用。 相似文献
54.
用X线形态学测量方法,对乌鲁木齐部分维吾尔族长寿老人及其家族成员的第二掌骨骨皮质进行了测量。结果表明10 ̄39岁组骨皮质厚度,皮质厚度指数,皮质面积随年龄增长而增大,30 ̄39岁组达到峰值,其中骨皮质厚度、皮质面积的数值男性〉女性,30 ̄39岁组差别有显著性。40岁以后各组数值开始下降,其下降速度女性快于男性,90岁以上组最为明显,有显著性差异。 相似文献
55.
人和大鼠腰椎关节突关节的SP能神经纤维的分布 总被引:2,自引:0,他引:2
目的:证实支配腰椎关节突关节的神经支配和化学性质,方法:用逆行荧光素标记结合免疫组化法,研究7只大鼠腰部脊神经节细胞的周围突分支投射到腰椎关节突关节及其递质性质以及3例人腰椎关节突关节囊上神经末梢的化学性质,结果:发现大鼠一侧L5和L6之间的关节突关节受同侧L2-5节段的脊神经节的部分细胞周围突分支支配,其中有33.399%的中型和小型细胞为中SP能免疫反应阳性,人的关节突关节囊含有SP阳性的神经 相似文献
56.
老年学习记忆减退大鼠齿状回突触的定量研究 总被引:2,自引:0,他引:2
据老年大鼠在Morris水迷宫中的行为表现,将其分为老年学习记忆减退和学习记忆正常两部分,采用透射电镜观察、拍片,对齿状回中分子层触的数量和大小进行体视学定量分析。 相似文献
57.
Byung Rae Jin Chun Jeih Ryu Sung Sup Park Namgung Uk Hyo Jeong Hong Moon Hi Han 《Molecular immunology》1993,30(18):1647-1654
The cloning, expression and characterization of a murine-human chimeric antibody with specificity for the pre-S2 surface antigen (Ag) of hepatitis B virus (HBV) is described. The heavy and light chain variable region (VH and VL) genes encoding the murine monoclonal antibody (mAb) were isolated and combined with human γ 1 and κ constant region genes, respectively. The expression vectors containing the chimeric heavy and light chain genes were sequentially electroporated into murine Sp2/0 hybridoma cells and transfectomas secreting chimeric antibody were isolated. The chimeric antibody was purified and characterized by ELISA, Western analysis and competition immunoassay, demonstrating that the transfectoma functionally express and secrete murine-human chimeric antibody which retained the specificity and affinity of the parental murine mAb. 相似文献
58.
59.
60.
Kokkotou E Philippon V Guèye-Ndiaye A Mboup S Wang WK Essex M Kanki P 《Journal of human virology》1998,1(7):469-474
OBJECTIVE: To determine the frequency of the mutant CCR5 delta 32 allele in high-risk HIV-seronegative Africans as compared with the general African population, and to assess its in vitro protective efficacy against HIV-1 infection. STUDY DESIGN: In the homozygous form, the CCR5 delta 32 allele confers resistance to macrophage-tropic (M-tropic) strains of HIV-1. Assuming that genetic characteristics favoring HIV resistance would prevail in a high-risk HIV-seronegative population, we examined the CCR5 genotypes of female commercial sex workers (CSWs) from Dakar, Senegal, who have remained uninfected for an elongated period. METHODS: The CCR5 genetic profile of study participants was determined by polymerase chain reaction (PCR) amplification of genomic DNA followed by sequencing. Peripheral blood mononuclear cells (PBMCs) were infected with different strains of HIV-1 and monitored by p24 enzyme-linked immunosorbent assay (ELISA). RESULTS: We confirmed the presence of two CCR5wt/delta 32 genotypes among 139 individuals (1.44%). PBMCs from these 2 heterozygous individuals were also found to be less susceptible to in vitro infection by an M-tropic HIV-1 primary isolate. CONCLUSIONS: Evidence was found of an increased prevalence of the CCR5wt/delta 32 genotype in a high-risk HIV-seronegative cohort in West Africa. Furthermore, reduced susceptibility to HIV-1 infection among heterozygous individuals supports a role for 32-bp CCR5 deletion in HIV-1 resistance. 相似文献