全文获取类型
收费全文 | 14768篇 |
免费 | 1048篇 |
国内免费 | 496篇 |
专业分类
耳鼻咽喉 | 215篇 |
儿科学 | 453篇 |
妇产科学 | 213篇 |
基础医学 | 1662篇 |
口腔科学 | 296篇 |
临床医学 | 1516篇 |
内科学 | 3020篇 |
皮肤病学 | 287篇 |
神经病学 | 920篇 |
特种医学 | 488篇 |
外国民族医学 | 2篇 |
外科学 | 1444篇 |
综合类 | 1384篇 |
一般理论 | 2篇 |
预防医学 | 1263篇 |
眼科学 | 491篇 |
药学 | 1169篇 |
7篇 | |
中国医学 | 451篇 |
肿瘤学 | 1029篇 |
出版年
2024年 | 24篇 |
2023年 | 130篇 |
2022年 | 263篇 |
2021年 | 469篇 |
2020年 | 319篇 |
2019年 | 379篇 |
2018年 | 550篇 |
2017年 | 395篇 |
2016年 | 381篇 |
2015年 | 520篇 |
2014年 | 627篇 |
2013年 | 734篇 |
2012年 | 1098篇 |
2011年 | 1214篇 |
2010年 | 735篇 |
2009年 | 532篇 |
2008年 | 831篇 |
2007年 | 859篇 |
2006年 | 743篇 |
2005年 | 784篇 |
2004年 | 658篇 |
2003年 | 623篇 |
2002年 | 570篇 |
2001年 | 479篇 |
2000年 | 504篇 |
1999年 | 388篇 |
1998年 | 116篇 |
1997年 | 101篇 |
1996年 | 101篇 |
1995年 | 91篇 |
1994年 | 54篇 |
1993年 | 51篇 |
1992年 | 143篇 |
1991年 | 118篇 |
1990年 | 102篇 |
1989年 | 107篇 |
1988年 | 88篇 |
1987年 | 75篇 |
1986年 | 66篇 |
1985年 | 50篇 |
1984年 | 38篇 |
1983年 | 23篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1977年 | 12篇 |
1973年 | 9篇 |
1970年 | 9篇 |
1965年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
The sequence is presented of RNA-5 of Echinochloa hoja blanca tenuivirus, a second tenuivirus associated with rice cultivation in Latin America (after rice hoja blanca virus). The RNA is 1334 nucleotides long and contains in the complementary sense RNA a single long open reading frame. The deduced amino acid sequence of this open reading frame shows that it encodes a highly basic and hydrophilic 44 kD protein (pc5) with about 50% similarity to the pc5 protein of maize stripe virus (MStV). This and other features of the RNA are discussed.The GenBank accession number of the sequence reported in this paper is L47430. 相似文献
92.
93.
Pucciarelli HM Orden AB Cesani MF Oyhenart EE Muñe MC Zucchi M 《Growth, development, and aging : GDA》2002,65(2):83-93
An experiment on rat undernutrition through seven generations was performed in order to see: (1) whether the nutritional stress on growth increases from one generation to the next, and (2) if an equilibrium point (AFP) in which the RFI--the amount of food intake (mg) per gram of body weight--reached is the same in both control and undernourished animals. The RFI values were calculated for each generation, between the 30th and 100th days of age. A moderate undernutrition was applied to the seven generations (F1 to F7) following the parental (P) one, which acted as controls. Undernourishment was made from conception to the end of the experiment (100 days old). The RFI values diminished with the age increment and increased through generations. There was, however, a clear AFP of 75.9 +/- 3.5 mg/g at 100 days of age in males, and of 78.7 +/- 4.2 mg/g at 90 days of age in females. A clear cumulative increment of RFI through the filial generations was also found at intermediate growth ages. The frequently argued nongenetic transmission of the nutritional deficiencies from parents to descendants was corroborated with the present results. Such cumulative effect was evident at ages before the AFP was reached; i.e., when the decrement in body mass of the undernourished animals was not yet equilibrated with the amount of available nutrients. 相似文献
94.
Jihai Xu Jing Wu Xiaofeng Teng Libing Cai Huizong Yuan Xiaokun Chen Mu Hu Xin Wang Ning Jiang Hong Chen 《American journal of medical genetics. Part A》2020,182(9):2117-2123
Polydactyly and syndactyly are digital abnormalities in limb‐associated birth defects usually caused by genetic disorders. In this study, a five‐generation Chinese pedigree was found with triphalangeal thumb polysyndactyly syndrome (TPTPS), showing an autosomal dominant pattern of inheritance. We utilized linkage analysis and whole genome sequencing (WGS) for the genetic diagnosis of this pedigree. Linkage analysis was performed using a genome‐wide single nucleotide polymorphism (SNP) chip and three genomic regions were identified in chromosomes 2, 6, and 7 with significant linkage signals. WGS discovered a copy number variation (CNV) mutation caused by a large duplication region at the tail of chromosome 7 located in exons 1–5 of the LMBR1 gene, including the zone of polarizing activity regulatory sequence (ZRS), with a length of approximately 180 kb. A real‐time polymerase chain reaction (PCR) assay confirmed the duplication. The findings of our study supported the notion that large duplications including the ZRS caused TPTPS. Our study showed that linkage analysis in combination with WGS could successfully identify the disease locus and causative mutation in TPTPS, which could help elucidate the molecular mechanisms and genotype–phenotype correlations in polydactyly. 相似文献
95.
Inhibition of caspase 3 abrogates lipopolysaccharide-induced nitric oxide production by preventing activation of NF-kappaB and c-Jun NH2-terminal kinase/stress-activated protein kinase in RAW 264.7 murine macrophage cells 下载免费PDF全文
Chakravortty D Kato Y Sugiyama T Koide N Mu MM Yoshida T Yokochi T 《Infection and immunity》2001,69(3):1315-1321
The effect of caspase inhibitors on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 267.4 murine macrophage cells was investigated. Pretreatment of RAW cells with a broad caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK), resulted in a striking reduction in LPS-induced NO production. Z-VAD-FMK inhibited LPS-induced NF-kappaB activation. Furthermore, it blocked phosphorylation of c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) but not that of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinases. Similarly, a caspase 3-specific inhibitor, Z-Asp-Glu-Val-Asp-fluoromethylketone, inhibited NO production, NF-kappaB activation, and JNK/SAPK phosphorylation in LPS-stimulated RAW cells. The attenuated NO production was due to inhibition of the expression of an inducible-type NO synthase (iNOS). The overexpression of the dominant negative mutant of JNK/SAPK and the addition of a JNK/SAPK inhibitor blocked iNOS expression but did not block LPS-induced caspase 3 activation. It was therefore suggested that the inhibition of caspase 3 might abrogate LPS-induced NO production by preventing the activation of NF-kappaB and JNK/SAPK. The caspase family, especially caspase 3, is likely to play an important role in the signal transduction for iNOS-mediated NO production in LPS-stimulated mouse macrophages. 相似文献
96.
97.
目的探讨脊肌萎缩症(SMA)的基因诊断方法.方法基于运动神经元生存基因(SMN)的两个同源拷贝碱基上的差异,应用PCR-酶切分析法对10例临床和病理诊断为Ⅰ、Ⅱ、Ⅲ型SMA的患者及其直系亲属16人、25例正常对照进行SMN基因检测.结果 10例SMA患者中9例患者缺失SMN第7、8号外显子,1例患者仅缺失第7号外显子;正常对照组及患者亲属均未发现外显子缺失.结论 PCR-酶切检测SMN基因第7号、8号外显子缺失是诊断儿童型脊肌萎缩症可靠的基因诊断方法. 相似文献
98.
鉴于热休克蛋白90β(hsp90β)基因内含子中含有维生素D3受体(VDR)结合位点,为探讨作为核受体家族成员的VDR是否对核受体特异分子伴侣的hsp90β基因的表达具有调控作用,我们开展了本项研究。分别将野生型VDR、含N端(1~133氨基酸残基)及C端(281~427氨基酸残基)片段的VDR突变体真核表达质粒与人hsp90β基因调控片段(-1039/+1531)介导的氯霉素乙酰基转移酶(CAT)报告基因质粒共转染Jurkat细胞,检测正常及经热休克(42℃,1h)处理后细胞裂解液中CAT活性。结果表明VDRN端增强、而C端抑制hsp90β的组成性表达;在热诱导条件下野生型VDR对hsp90β的表达有一定的抑制作用,而其C端片段的抑制较强。为进一步研究VDR对细胞内源性热休克基因表达的影响,我们用RTPCR方法研究了VDR的对细胞内hsp90β基因mRNA水平的影响,发现VDR过表达对hsp90β的热诱导表达明显抑制。结果提示VDR对hsp90β基因的组成性和热诱导表达的调控机制不同。 相似文献
99.
da Cunha JP Nakayasu ES Elias MC Pimenta DC Téllez-Iñón MT Rojas F Muñoz MJ Manuel M Almeida IC Schenkman S 《Molecular and biochemical parasitology》2005,140(1):75-86
Histone H1 of most eukaryotes is phosphorylated during the cell cycle progression and seems to play a role in the regulation of chromatin structure, affecting replication and chromosome condensation. In trypanosomatids, histone H1 lacks the globular domain and is shorter when compared with the histone of other eukaryotes. We have previously shown that in Trypanosoma cruzi, the agent of Chagas' disease, histone H1 is phosphorylated and this increases its dissociation from chromatin. Here, we demonstrate using mass spectrometry analysis that T. cruzi histone H1 is only phosphorylated at the serine 12 in the sequence SPKK, a typical cyclin-dependent kinase site. We also found a correlation between the phosphorylation state of histone H1 and the cell cycle. Hydroxyurea and lactacystin, which, respectively, arrest parasites at the G1/S and G2/M stages of the cell cycle, increased the level of histone H1 phosphorylation. Cyclin-dependent kinase-related enzymes TzCRK3, and less intensely the TzCRK1 were able to phosphorylate histone H1 in vitro. Histone H1 dephosphorylation was prevented by treating the parasites with okadaic acid but not with calyculin A. These findings suggest that T. cruzi histone H1 phosphorylation is promoted by cyclin dependent kinases, present during S through G2 phase of the cell cycle, and its dephosphorylation is promoted by specific phosphatases. 相似文献
100.
Su M Tokairin T Nishikawa Y Yoshioka T Takahashi O Watanabe H Doi Y Omori Y Yoshioka T Sageshima M Tanaka T Enomoto K 《Pathology international》2002,52(2):158-163
A rare case of rapidly growing osteosarcoma that developed in the uterine corpus of a 62-year-old woman is presented. The tumor occupied almost the entire pelvic cavity and extended into the abdominal cavity, with marked involvement of the intestines. Histopathologically, the tumor was composed of an osteoblastic component, accompanied by conspicuous bone formation, and a fibroblastic component. The tumor cells were positive for vimentin and osteocalcin, as well as desmin, alpha-smooth muscle actin and muscle-specific actin, but negative for h-caldesmon. The results indicated myofibroblastic differentiation in a part of the tumor. A review of 14 reported cases and our case of uterine osteosarcoma revealed that this tumor has a biologically aggressive nature, although its histopathological and immunohistochemical features are similar to those of osteosarcomas in soft tissue and bone. As the prognosis of patients with this tumor is poor, it is of importance to differentiate this tumor from other types of tumors arising from the uterine corpus. 相似文献