全文获取类型
收费全文 | 9224篇 |
免费 | 879篇 |
国内免费 | 993篇 |
出版年
2024年 | 18篇 |
2023年 | 56篇 |
2022年 | 173篇 |
2021年 | 336篇 |
2020年 | 276篇 |
2019年 | 373篇 |
2018年 | 382篇 |
2017年 | 308篇 |
2016年 | 399篇 |
2015年 | 581篇 |
2014年 | 668篇 |
2013年 | 730篇 |
2012年 | 847篇 |
2011年 | 815篇 |
2010年 | 587篇 |
2009年 | 569篇 |
2008年 | 596篇 |
2007年 | 536篇 |
2006年 | 444篇 |
2005年 | 412篇 |
2004年 | 337篇 |
2003年 | 337篇 |
2002年 | 305篇 |
2001年 | 208篇 |
2000年 | 134篇 |
1999年 | 113篇 |
1998年 | 87篇 |
1997年 | 74篇 |
1996年 | 47篇 |
1995年 | 44篇 |
1994年 | 46篇 |
1993年 | 35篇 |
1992年 | 49篇 |
1991年 | 31篇 |
1990年 | 22篇 |
1989年 | 28篇 |
1988年 | 21篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 15篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
952.
We report the full-genome sequence of a goose-origin reovirus (GRV) strain 03G from Zhejiang Province, China. This is the first report of the complete genomic sequence (segments 1 to 10) of GRV. Phylogenetic analyses of the sequence suggest that GRV 03G represents a new species distinct from other established species within the avian reovirus (ARV) group of orthoreoviruses. 相似文献
953.
Teng L Yu M Li JM Tang H Yu J Mo LH Jin J Liu XZ 《Molecular and cellular biochemistry》2012,360(1-2):271-277
Multiple organ dysfunction syndrome (MODS) is an important cause of morbidity and mortality in intensive care unit. A severe insult in the form of infection or trauma primes the host immune system so that a subsequent, relatively trivial insult produces systemic inflammation response syndrome, which can lead to MODS and death. Matrix metalloproteinase-9 (MMP-9) is stored in the tertiary granules of polymorphonuclear leukocytes. These cells are key effectors in acute inflammatory diseases, such as sepsis and MODS. Endotoxin leads to rapid release of MMP-9 from these granules in vitro and in vivo. However, the role of this enzyme in MODS, and whether it is associated with organ injury at the early stage of MODS remains unclear. This present work may study role of MMP-9 with the MODS rats that caused by trauma and infection and investigate the mechanism of organ injury at the early stage of MODS. Here, we developed a rat model for MODS caused by trauma and infection and analyzed the dynamic level of MMP-9 and determined the relationship between MMP-9 level and early phase of organ injury in MODS rat. The histological changes in pulmonary, renal, and hepatic tissue were observed by light microscope. The expressions of plasma MMP-9 proteins were detected by an enzyme linked immunosorbent assay and its levels in the pulmonary, renal, and hepatic tissue were detected by using immunohistochemistry, respectively. The results indicated that there were no significant improvements in histopathology of rats in control group. However, the pulmonary, renal, and hepatic damage were serious in MODS groups. The concentration of MMP-9 in plasma and tissues of MODS rats increased markedly at the early stage and were higher than that of the control group. Moreover, the MMP-9 level in plasma positively correlated with the levels of pulmonary, renal, and hepatic tissue. This study clearly shows that MMP-9 is good biomarker to predict the severity of injury organ at the early phase of MODS. 相似文献
954.
Lin X Peng P Cheng L Chen S Li K Li ZY Mo YH Zhou Z Li M 《Differentiation; research in biological diversity》2012,83(1):1-9
An intra-myocardial injection of a cardiogenic factor (cardiogenin) was reported to induce myocardial regeneration of exogenous mesenchymal stem cell (MSCs) origin. In this study, replacement of the dangerous intra-myocardial injection with a safe method and whether the endogenous MSCs contribute to the cardiogenin-mediated myocardial regeneration were investigated. Bone marrow transplantation with labeled MSCs was performed in rats, which were subsequently subject to a permanent ligation of left anterior descending coronary artery one week after the transplantation. The rats were then treated with the cardiogenin through oral administration for 2 weeks. We not only demonstrated the substantial therapeutic effects of cardiogenin on myocardial infarction through an oral administration, but also provided direct evidences that the bone marrow derived endogenous MSCs are the major cellular source of the regenerating myocardium. Preliminary mechanistic studies suggested that miR-9 and its target E-cadherin may be required for intercalated disc formation. 相似文献
955.
Flavonols are produced by the desaturation of dihydroflavanols, which is catalyzed by flavonol synthase (FLS). FLS belongs
to the 2-oxoglutarate iron-dependent oxygenase family. The full-length cDNA and genomic DNA sequences of the FLS gene (designated as GbFLS) were isolated from Ginkgo biloba. The full-length cDNA of GbFLS contained a 1023-bp open reading frame encoding a 340-amino-acid protein. The GbFLS genomic DNA had three exons and two introns. The deduced GbFLS protein showed high identities with other plant FLSs. The
conserved amino acids (H–X–D) ligating ferrous iron and residues (R–X–S) participating in 2-oxoglutarate binding were found
in GbFLS at similar positions like other FLSs. GbFLS was found to be expressed in all tested tissues including roots, stems,
leaves, and fruits. Expression profiling analyses revealed that GbFLS expression was induced by all of the six tested abiotic stresses, namely, UV-B, abscisic acid, cold, sucrose, salicylic acid,
and ethephon, consistent with the in silico analysis results of the promoter region. The recombinant protein was successfully
expressed in the E. coli strain BL21 (DE3) with a pET-28a vector. The in vitro enzyme activity assay by high performance liquid chromatography indicated
that recombinant GbFLS protein could catalyze the formation of dihydrokaempferol to kaempferol and the conversion of kaempferol
from naringenin, suggesting that GbFLS is a bifunctional enzyme within the flavonol biosynthetic pathway. 相似文献
956.
Hu M Jian L Zhang L Zheng J You Y Deng J Li H Zhou Y 《Molecular biology reports》2012,39(7):7303-7309
The epithelial cell adhesion molecule (EpCAM) was originally identified as a tumor associated antigen, attributable to its high expression on rapidly proliferating tumors of epithelial origin. EpCAM plays vital roles in carcinogenesis, tumor progression and metastasis in most tumors. A non-synonymous polymorphism (rs1126497 C/T) was found in exon 3 of EpCAM, which cause a transition from 115 Met to 115 Thr. Another polymorphism (rs1421 A/G) in the 3'UTR causes loss of has-miR-1183 binding. We performed a multiple independent case-control analysis to assess the association between EpCAM genotypes and cervical cancer risk. Genotyping a total of 518 patients with cervical cancer and 723 control subjects in a Chinese population, we observed that the variant EpCAM genotypes (rs1126497 CT, and TT) were associated with substantially increased risk of cervical cancer. Compared with the rs1126497 CC genotype, CT genotype had a significantly increased risk of cervical cancer (Crude OR = 1.70; 95% CI = 1.33-2.20; adjusted OR = 1.72; 95% CI = 1.33-2.22), the TT carriers had a further increased risk of cervical cancer (Crude OR = 1.94; 95% CI = 1.01-3.72; adjusted OR = 1.96; 95%CI = 1.01-3.81), and there was a trend for an allele dose effect on risk of cervical cancer (P < 0.001). Moreover, the allele T increases the risk for invasive disease or metastatic disease, compared with C allele. However, there exists no significant difference in genotype frequencies of rs1421 A/G site between cases and controls (P = 0.798). These findings suggest that rs1126497 C/T polymorphism in EpCAM may be a genetic modifier for developing cervical cancer. 相似文献
957.
958.
Geranylgeranyl diphosphate (GGPP) synthase is an important branch point enzyme in terpenoid biosynthesis. It regulates the
formation of diterpenoid, such as tanshinones. We cloned a gene for GGPP synthase SmGGPPs involved in diterpenoid biosynthesis from Salvia miltiorrhiza. At 2,767 bp long, this gene comprises an intron and two exons that encode a polypeptide of 364 amino acid residues. Then
the 5′ flanking sequence of SmGGPPs was characterized by bioinformatics method. Deletion analysis of the promoter of SmGGPPs using tobacco plant displayed that the promoter was induced by heat and cold. To further search these cis-elements involved
in induction regulation in the 5′ flanking sequence of SmGGPPs, many putative cis-elements were predicted with the PlantCARE and PLACE databases. A group of putative cis-acting elements
are involved in induction regulation, including G-Box, WRKY, MYC and ATCT motifs. Real-time PCR analysis revealed that SmGGPPs is mainly expressed in the leaves and can also be induced by various factors, such as NaCl, wounding, high temperature, darkness,
pathogen, methyl jasmonate, abscisic acid, salicylic acid, and gibberellins. This study provides useful information for further
study of SmGGPPs and its regulator effect on the biosynthetic process of tanshinones so that researchers can improve the tanshinone contents
in S. miltiorrhiza. 相似文献
959.
Zhang WB Qiu PC Jiang HW Liu CY Xin da W Li CD Hu GH Chen QS 《Molecular biology reports》2012,39(5):6087-6094
Northeast of China is the main soybean production area, drought and low-temperature tolerance are both main factors involved
in reducing soybean yield and limiting planting regions, the most effective way to solve this problem is to breed cultivars
with drought and low-temperature tolerance. A set of the BC2F3 lines was constructed with Hongfeng 11 as recurrent parent and Harosoy as donor parent, and screened in drought and low-temperature
condition at the germination stage. Related QTLs were obtained by Chi-test and ANOVA analysis with genotypic and phenotypic
data. Eighteen QTLs of drought tolerance and 23 QTLs of low-temperature tolerance were detected. Among them, 12 QTLs were
correlated with both drought and low-temperature tolerance, which showed a partial genetic overlap between drought and low-temperature
tolerance at the germination stage in soybean. Among the 12 genetic overlap QTLs, Satt253, Satt513, Satt693, Satt240, Satt323,
and Satt255 were detected by at least one method for both drought and low-temperature tolerance. Satt557, Satt452, Sat_331,
Satt338, Satt271, and Satt588 were detected by only one analysis method. The QTLs detected above were significant loci for
drought or low-temperature tolerance in soybean. This will play an important role in MAS for development of both drought and
low-temperature tolerance variety. 相似文献
960.
In clinical practice, most patients with non small cell lung cancer (NSCLC) who respond to tyrosine kinase inhibitors eventually
progress because of an acquired resistance mutation, T790M, in epidermal growth factor receptor (EGFR). Thus, it is important
to identify a new drug to reduce resistance. The aim of this study was to test whether genistein combined with gefitinib is
effective against NSCLC in a cell line carrying T790M, and to clarify the underlying mechanisms. The human lung cancer cell
line H1975 was used as an in vitro and in vivo model. Cells were treated with gefitinib, genistein, or a combination at a
range of concentrations. Cell proliferation was calculated to assess the anticancer effects of the compounds in vitro. Flow
cytometry and Western blotting were employed to determine the inhibitory effects on proliferation and the induction of apoptosis.
The in vivo effects of the compounds were examined using a xenografted nude mouse model for validation. Gefitinib together
with genistein enhanced both growth inhibition and apoptosis; however, the greatest synergistic effect was observed at low
concentrations. p-EGFR, p-Akt, and p-mTOR expressions in vitro were reduced more by the combined use of the drugs, whereas
caspase-3 and PARP activities were increased. Significantly more tumor growth inhibition was detected following combination
treatment in the in vivo model. These findings suggest that genistein enhanced the antitumor effects of gefitinib in a NSCLC
cell line carrying the T790M mutation. This synergistic activity may be due to increased inhibition of the downstream molecular
and pro-apoptotic effects of EGFR. 相似文献