全文获取类型
收费全文 | 2334篇 |
免费 | 29篇 |
国内免费 | 251篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 6篇 |
2019年 | 15篇 |
2018年 | 23篇 |
2017年 | 17篇 |
2016年 | 20篇 |
2015年 | 34篇 |
2014年 | 183篇 |
2013年 | 212篇 |
2012年 | 187篇 |
2011年 | 176篇 |
2010年 | 135篇 |
2009年 | 159篇 |
2008年 | 222篇 |
2007年 | 209篇 |
2006年 | 190篇 |
2005年 | 164篇 |
2004年 | 120篇 |
2003年 | 92篇 |
2002年 | 93篇 |
2001年 | 56篇 |
2000年 | 47篇 |
1999年 | 45篇 |
1998年 | 58篇 |
1997年 | 42篇 |
1996年 | 39篇 |
1995年 | 23篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 3篇 |
排序方式: 共有2614条查询结果,搜索用时 15 毫秒
31.
32.
Stone fruits and pome fruits are cultivated commercially worldwide. In India, they are grown in temperate regions, which mainly includes Jammu and Kashmir, Uttarakhand, Himachal Pradesh and some North-Eastern states. In this study, an attempt has been made to identify the Prunus necrotic ringspot virus (PNRSV) infecting stone and pome fruits in India and to characterise them on the molecular level. Surveys were conducted in the temperate fruit-growing areas and incidence of PNRSV was detected by serological and molecular means in almond, apple, cherry, nectarine, peach, plum and wild cherry. Further diversity analysis of PNRSV was performed using bioinformatics tools such as clustalW, DNA Data Bank of Japan, MultAlin and Recombination Detection Programme. PNRSV was detected in plum, peach, cherry, almond, nectarine, wild cherry and apple. In the diversity analysis study on the basis of coat protein gene, it was found that the isolates showed identity levels from 82 to 100%. In a plum isolate, a stretch of amino acids from 207 to 221 was found variable from Indian and other isolates. In one of the Indian apple isolates, “NR” repeats at 41–44 position (characteristic of PV-32 group, Group I) were identified. Phylogenetic analysis revealed that Indian isolates are falling in Group-I. Movement protein was also amplified from peach and multiple alignment studies showed that N-terminus was mostly conserved, whereas the C-terminal was highly variable. 相似文献
33.
34.
Flavia M. Gonçalves Alisson Martins-Oliveira Riccardo Lacchini Vanessa A. Belo Jose G. Speciali Fabíola Dach Jose E. Tanus-Santos 《Gene》2013
Matrix metalloproteinases (MMP) are involved in the disruption of blood–brain barrier (BBB) during migraine attacks. In the present study, we hypothesized that two functional polymorphisms (C− 1306T and C− 735T) in MMP-2 gene and MMP-2 haplotypes are associated with migraine and modify MMP-2 and tissue inhibitor of MMP (TIMP)-2 levels in migraine. Genotypes for MMP-2 polymorphisms were determined by real time-PCR using Taqman allele discrimination assays. Haplotypes were inferred using the PHASE program. Plasma MMP-2 and TIMP-2 concentrations were measured by gelatin zymography and ELISA, respectively, in 148 healthy women without history of migraine and in 204 women with migraine (153 without aura; MWA, and 51 with aura; MA). Patients with MA had higher plasma MMP-2 concentrations and MMP-2/TIMP-2 ratios than patients with MWA and controls (P < 0.05). While MMP-2 genotype and haplotype distributions for the polymorphisms were similar among the groups (P > 0.05), we found that the CC genotype for C− 735T polymorphism and the CC haplotype were associated with higher plasma MMP-2 concentrations in MA group (P < 0.05). Our findings may help to understand the role of MMP-2 and its genetic variants in the pathophysiology of migraine and to identify a particular group of migraine patients with increased MMP-2 levels that would benefit from the use of MMP inhibitors. 相似文献
35.
36.
37.
38.
Chuanyan Yang Lingling Wang Qiufen Jiang Jingjing Wang Feng Yue Huan Zhang Zhibin Sun Linsheng Song 《Gene》2013
Metallothioneins (MTs), a superfamily of cysteine-rich proteins, perform multiple functions, such as maintaining homeostasis of essential metals, detoxification of toxic metals and scavenging of oxyradicals. In this study, the promoter region of a metallothionein (MT) gene from Bay scallop Argopecten irradians (designed as AiMT1) was cloned by the technique of genomic DNA walking, and the polymorphisms in this region were screened to find their association with susceptibility or tolerance to high temperature stress. One insert–deletion (ins–del) polymorphism and sixteen single nucleotide polymorphisms (SNPs) were identified in the amplified promoter region. Two SNPs, − 375 T–C and − 337 A–C, were selected to analyze their distribution in the two Bay scallop populations collected from southern and northern China coast, which were identified as heat resistant and heat susceptible stocks, respectively. There were three genotypes, T/T, T/C and C/C, at locus − 375, and their frequencies were 25%, 61.1% and 13.9% in the heat susceptible stock, while 34.2%, 42.1% and 23.7% in the resistant stock, respectively. There was no significant difference in the frequency distribution of different genotypes between the two stocks (P > 0.05). In contrast, at locus − 337, three genotypes A/A, A/C and C/C were revealed with the frequencies of 11.6%, 34.9% and 53.5% in the heat susceptible stock, while 45.7%, 32.6% and 21.7% in the heat resistant stock, respectively. The frequency of C/C genotype in the heat susceptible stock was significantly higher (P < 0.01) than that in the heat resistant stock, while the frequency of A/A in the heat resistant stock was significantly higher (P < 0.01) than that in the heat susceptible stock. Furthermore, the expression of AiMT1 mRNA in scallops with C/C genotype was significantly higher than that with A/A genotype (P < 0.05) after an acute heat treatment at 28 °C for 120 min. These results implied that the polymorphism at locus − 337 of AiMT1 was associated with the susceptibility/tolerance of scallops to heat stress, and the − 337 A/A genotype could be a potential marker available in future selection of Bay scallop with heat tolerance. 相似文献
39.
40.