全文获取类型
收费全文 | 18687篇 |
免费 | 1465篇 |
国内免费 | 465篇 |
专业分类
耳鼻咽喉 | 118篇 |
儿科学 | 331篇 |
妇产科学 | 121篇 |
基础医学 | 3839篇 |
口腔科学 | 426篇 |
临床医学 | 1493篇 |
内科学 | 3438篇 |
皮肤病学 | 257篇 |
神经病学 | 2853篇 |
特种医学 | 330篇 |
外国民族医学 | 2篇 |
外科学 | 1511篇 |
综合类 | 1717篇 |
现状与发展 | 4篇 |
预防医学 | 861篇 |
眼科学 | 282篇 |
药学 | 1808篇 |
9篇 | |
中国医学 | 697篇 |
肿瘤学 | 520篇 |
出版年
2024年 | 48篇 |
2023年 | 396篇 |
2022年 | 633篇 |
2021年 | 919篇 |
2020年 | 743篇 |
2019年 | 753篇 |
2018年 | 726篇 |
2017年 | 623篇 |
2016年 | 622篇 |
2015年 | 611篇 |
2014年 | 1104篇 |
2013年 | 1315篇 |
2012年 | 915篇 |
2011年 | 1021篇 |
2010年 | 826篇 |
2009年 | 855篇 |
2008年 | 836篇 |
2007年 | 758篇 |
2006年 | 633篇 |
2005年 | 621篇 |
2004年 | 511篇 |
2003年 | 444篇 |
2002年 | 347篇 |
2001年 | 328篇 |
2000年 | 298篇 |
1999年 | 288篇 |
1998年 | 318篇 |
1997年 | 343篇 |
1996年 | 284篇 |
1995年 | 265篇 |
1994年 | 252篇 |
1993年 | 219篇 |
1992年 | 180篇 |
1991年 | 173篇 |
1990年 | 145篇 |
1989年 | 155篇 |
1988年 | 110篇 |
1987年 | 112篇 |
1986年 | 89篇 |
1985年 | 178篇 |
1984年 | 141篇 |
1983年 | 121篇 |
1982年 | 91篇 |
1981年 | 79篇 |
1980年 | 65篇 |
1979年 | 42篇 |
1978年 | 29篇 |
1977年 | 21篇 |
1976年 | 13篇 |
1973年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
RNA干扰(RNAi)是细胞内由双链RNA诱导降解与其配对的特定mRNA的过程。细胞内双链RNA在酶的作用下,形成20-25碱基大小的小干扰RNA(si RNAs),由si RNAs进一步掺入多组分核酸酶并使其激活,从而精确降解与si RNAs序列相同的mRNA,抑制该基因在细胞内的翻译表达。介绍了RNA干扰的分子机制、制备方法、以及RNA干扰技术在功能基因组学、微生物学、基因治疗和信号转导等研究领域里的应用。 相似文献
102.
Kimura S Sato T Takahashi T Narita T Hirano S Goto M 《Psychiatry and clinical neurosciences》2000,54(2):181-189
Although many clinical studies have been conducted to determine the etiological role and clinical implications of typus melancholicus for unipolar depression, maladaptive personality features in depressive patients have not been well described. This study explores typus melancholicus, as measured by the rigidity subscale of the Munich Personality Test, and maladaptive personality features, as measured by the Temperament and Character Inventory (TCI), in 131 remitted patients with DSM-IV major depression and 154 normal controls. The patients reported significantly higher scores on rigidity and harm avoidance and significantly lower scores on self-directedness and cooperativeness. Only 23.6% of the variance of the rigidity scale was explained by the variance of the seven TCI scales, in which only persistence was significantly correlated positively to rigidity. Cluster analysis identified four subgroups, two of which were characterized by a high rigidity score. One of these two subgroups showed no maladaptive personality features, as measured by the TCI, while the other showed high harm avoidance and low self-directedness. These results indicate that the personality of depressive patients is characterized not only by typus melancholicus but also by maladaptive personality features, that typus melancholicus is not well represented by any TCI scale, and that typus melancholicus and maladaptive personality features can coexist in some depressive patients. 相似文献
103.
目的探讨侵袭性垂体腺瘤MRI与肿瘤上皮钙黏蛋白/连接素复合体(E—eadherin catenin complex)在反映肿瘤侵袭性方面的关系。资料与方法在MR图像上对病理证实的31例垂体腺瘤进行测量。根据肿瘤对周围结构的侵袭程度,计算侵袭性累计分数,并将该结果与肿瘤上皮钙黏蛋白/连接素复合体免疫组织化学法染色结果相比较。结果19例腺瘤β连接素(β-catenin)染色结果与累计侵袭分数呈显著线性负相关(r=-0.477,P=0.039)。上皮钙黏蛋白(E—cadherin)和α连接素(α—catenin)染色结果与累计侵袭分数无显著线性相关(分别是r1=-0.018,P=0.930;r2=0.032,P=0.870)。结论侵袭性垂体腺瘤β-catenin表达的减少程度与MRI显示腺瘤侵袭周围结构的程度呈正相关,MRI结合peatenin表达水平可以更好地评价腺瘤的侵袭性。 相似文献
104.
Jiahao Cai Zixin Wei Ming Chen Lei He Hongxuan Wang Mei Li Ying Peng 《European psychiatry》2022,65(1)
BackgroundThere is increasing attention on the association of socioeconomic status and individual behaviors (SES/IB) with mental health. However, the impacts of SES/IB on mental disorders are still unclear. To provide evidence for establishing feasible strategies on disease screening and prevention, we implemented Mendelian randomization (MR) design to appraise causality between SES/IB and mental disorders.MethodsWe conducted a two-sample MR study to assess the causal effects of SES and IB (dietary habits, habitual physical activity, smoking behaviors, drinking behaviors, sleeping behaviors, leisure sedentary behaviors, risky behaviors, and reproductive behaviors) on three mental disorders, including bipolar disorder, major depressive disorder and schizophrenia. A series of filtering steps were taken to select eligible genetic instruments robustly associated with each of the traits. Inverse variance weighted was used for primary analysis, with alternative MR methods including MR-Egger, weighted median, and weighted mode estimate. Complementary methods were further used to detect pleiotropic bias.ResultsAfter Bonferroni correction and rigorous quality control, we identified that SES (educational attainment), smoking behaviors (smoking initiation, number of cigarettes per day), risky behaviors (adventurousness, number of sexual partners, automobile speeding propensity) and reproductive behavior (age at first birth) were causally associated with at least one of the mental disorders.ConclusionsMR study provides robust evidence that SES/IB play broad impacts on mental disorders. 相似文献
105.
Tomohiro Kaneko Sakiko Miyazaki Takuma Koike Azusa Murata Ryoko Morimoto Kuniaki Hirose Kazuhisa Takamura Daisuke Endo Atsushi Amano Tohru Minamino 《Internal medicine (Tokyo, Japan)》2022,61(9):1367
Atypical Shone''s complex is a rare congenital anomaly involving a left-sided obstructive lesion of two or three cardiovascular levels. A 70-year-old man with dyspnea on exertion was diagnosed with severe aortic stenosis (AS) with a bicuspid valve, complicated by severe aortic coarctation (CoA) and a double-orifice mitral valve. He underwent surgery for AS and CoA in one session. It is important to search for complicated malformations, even in cases of bicuspid aortic valve found in old age. 相似文献
106.
目的 探究比较不同涂布方法对复杂柔性硅胶血管仿体制作质量的影响。方法 基于个性化前交通动脉瘤模型,采用喷涂和旋涂两种方法,制作多例硅胶血管仿体,定量比较两种方法在制作同一血管结构时的厚度增长、周向均匀以及透光性等指标。结果 旋涂法在血管大曲率、变径位置和直管位置处的厚度控制以及厚度均匀性占优,且具有较好的透光性和表面光滑性。旋涂法厚度相对偏差较喷涂法分别降低8.9%、10.8%和16.9%。结论 现阶段旋涂法在制作硅胶仿体模型时较喷涂法具有厚度均匀性优势和透光性优势,在大血管流体力学体外实验领域具有十分可期的应用前景。 相似文献
107.
Bacteriophage JC1 is a Podoviridae phage with a C1 morphotype, isolated on host strain Burkholderia cenocepacia Van1. Phage JC1 is capable of infecting an expansive range of Burkholderia cepacia complex (Bcc) species. The JC1 genome exhibits significant similarity and synteny to Bcep22-like phages and to many Ralstonia phages. The genome of JC1 was determined to be 61,182 bp in length with a 65.4% G + C content and is predicted to encode 76 proteins and 1 tRNA gene. Unlike the other Lessieviruses, JC1 encodes a putative helicase gene in its replication module, and it is in a unique organization not found in previously analyzed phages. The JC1 genome also harbours 3 interesting moron genes, that encode a carbon storage regulator (CsrA), an N-acetyltransferase, and a phosphoadenosine phosphosulfate (PAPS) reductase. JC1 can stably lysogenize its host Van1 and integrates into the 5′ end of the gene rimO. This is the first account of stable integration identified for Bcep22-like phages. JC1 has a higher global virulence index at 37 °C than at 30 °C (0.8 and 0.21, respectively); however, infection efficiency and lysogen stability are not affected by a change in temperature, and no observable temperature-sensitive switch between lytic and lysogenic lifestyle appears to exist. Although JC1 can stably lysogenize its host, it possesses some desirable characteristics for use in phage therapy. Phage JC1 has a broad host range and requires the inner core of the bacterial LPS for infection. Bacteria that mutate to evade infection by JC1 may develop a fitness disadvantage as seen in previously characterized LPS mutants lacking inner core. 相似文献
108.
中药制剂及外源性细胞因子对化疗损伤小鼠细胞因子及NK细胞活性的影响 总被引:1,自引:0,他引:1
目的研究人参养荣片组方、单味药(人参、当归、黄芪、白术)及单独注射G-CSF对化疗损伤小鼠细胞因子及NK细胞活性的影响.方法酶标双抗体夹心法测定用药后各组小鼠血清中细胞因子(IL-6、IL-12、EP0、G-CSF)含量;小鼠胸腺细胞增殖法(MTT法)测定血清及巨噬细胞培养上清中IL-1含量;NK细胞杀伤靶细胞K562(MTT法)测定NK细胞活性.结果人参可升高血清G-CSF、IL-12,当归可升高巨噬细胞培养上清IL-1及血清IL-12,二者均可增强NK活性;黄芪、白术均可使血清中IL-1、IL-6含量升高.人参养荣片可以将化疗损伤小鼠IL-1、IL-6、IL-12、EPO、G-CSF及NK细胞活性调整至正常水平,但不是单味药作用的累加.注射外源G-CSF 后G-CSF、IL-12、NK细胞活性略有升高,IL-1、IL-6、EP0的变化不明显.结论中草药拮抗化疗损伤可能是通过调节多种细胞因子实现的. 相似文献
109.
110.
糖尿病性黄斑水肿( diabetic macular edema ,DME)是糖尿病患者视功能损害的主要原因,中央视网膜厚度( central retinal thickness,CRT)与DME患者视功能损害及治疗前后视功能变化密切相关,而黄斑部视网膜微结构改变与CRT变化有关。频域 OCT ( spectral-domain OCT, SD-OCT)可以定性、定量的分析黄斑各组织层次的细微结构。我们对DME患者黄斑部视网膜微结构SD-OCT改变的相关研究进展进行综述,对进一步探讨DME的发病机制、观察病情进展、指导临床治疗及判断预后情况有重要意义。 相似文献