全文获取类型
收费全文 | 154618篇 |
免费 | 22776篇 |
国内免费 | 6363篇 |
专业分类
183757篇 |
出版年
2024年 | 274篇 |
2023年 | 1803篇 |
2022年 | 2762篇 |
2021年 | 4077篇 |
2020年 | 5922篇 |
2019年 | 8515篇 |
2018年 | 8029篇 |
2017年 | 7099篇 |
2016年 | 6940篇 |
2015年 | 7578篇 |
2014年 | 10415篇 |
2013年 | 12522篇 |
2012年 | 8417篇 |
2011年 | 10071篇 |
2010年 | 8097篇 |
2009年 | 7921篇 |
2008年 | 8251篇 |
2007年 | 7987篇 |
2006年 | 7369篇 |
2005年 | 6345篇 |
2004年 | 5527篇 |
2003年 | 4944篇 |
2002年 | 4459篇 |
2001年 | 3126篇 |
2000年 | 2456篇 |
1999年 | 2299篇 |
1998年 | 2127篇 |
1997年 | 1740篇 |
1996年 | 1665篇 |
1995年 | 1539篇 |
1994年 | 1381篇 |
1993年 | 1239篇 |
1992年 | 1141篇 |
1991年 | 1001篇 |
1990年 | 842篇 |
1989年 | 697篇 |
1988年 | 649篇 |
1987年 | 575篇 |
1986年 | 478篇 |
1985年 | 668篇 |
1984年 | 911篇 |
1983年 | 666篇 |
1982年 | 732篇 |
1981年 | 533篇 |
1980年 | 432篇 |
1979年 | 366篇 |
1978年 | 298篇 |
1977年 | 218篇 |
1976年 | 175篇 |
1975年 | 140篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
《Saudi Journal of Biological Sciences》2022,29(2):831-839
The survival reduction after transplantation limited the clinical uses of stem cells so the current study explored preconditioning adipose-derived stem cells (ADMSCs) and all-trans retinoic acid (ATRA) effects on cisplatin that caused acute kidney injury (AKI). One hundred and fifty Sprague–Dawley male rats were distributed into five groups: control group; Cisplatin (CIS) group; CIS and ATRA group; CIS and ADMSC group, and CIS, ATRA, and ADMSCs group. Ten rats were euthanized after 3rd, 7th, and 11th days from CIS injection. Renal function, molecular studies, and histopathological analysis were studied. The preconditioning of ADMSCs with ATRA increased the viability of the cells which was reflected in the amelioration of kidney functions after CIS injection by the significant reduction of serum creatinine, microalbuminuria, as well as NO, and the significant rise of creatinine clearance, as well as SOD compared to the group of cisplatin. ATRA also supported ADMSCs by a significant down-regulation of caspase-3, il-6 and TGFβ1, and a significant up-regulation of HIF1, VEGF and CD31 compared to group of cisplatin which reversed the cisplatin effect. ATRA increased renoprotective properties of ADMSCs against cisplatin- induced AKI by reducing the apoptosis, inflammation, and stimulating angiogenesis. 相似文献
992.
Wang Y Puntenney SB Burton JL Forsberg NE 《Animal : an international journal of animal bioscience》2007,1(7):945-951
In the first study, we tested the ability of a commercial feed additive (OmniGen-AF) to affect markers of innate immunity in immunosuppressed sheep and the ability of a pathogen challenge (mould) to affect the immune response to the additive. Treatments consisted of (1) control, (2) immunosuppressed with dexamethasone (DEX), (3) immunosuppressed plus the feed additive, (4) immunosuppressed plus Aspergillus fumigatus and (5) immunosuppressed, A. fumigatus and the additive. Animal health was monitored and indexes of innate immunity (neutrophil L-selectin and interleukin-1β (IL-1β)) were collected. DEX caused immunosuppression (i.e. reduced abundance of neutrophil L-selectin and IL-1β). This immunosuppressive effect was countered by the provision of the additive in the ration. Provision of mould in the ration increased the ability of the additive to regulate markers of innate immune function. A second study was completed to re-assess the properties of the additive and other feed products. The study consisted of seven treatments: (1) immunosuppressed, (2) immunosuppressed with additive, (3) immunosuppressed with additive in pelleted form (low-temperature pellet) and (4) immunosuppressed with additive in a high-temperature pellet. The remaining three treatments assessed abilities of three other additives to regulate markers of innate immune function. In this study, OmniGen-AF increased expression of neutrophil L-selectin abundance in immunosuppressed animals and this was unaffected by the pelleting temperature. None of the other additives affected markers of innate immunity. In these studies we discovered mechanisms by which a feed product may affect the immune function of ruminant livestock. The product countered DEX-dependent down-regulation of markers of innate immune function and its actions were enhanced by the presence of pathogen (mould) in the ration. 相似文献
993.
The latest emergence of influenza A (H1N1) virus outbreak demonstrated how swiftly a new strain of flu can evolve and spread around the globe. The A/H1N1 flu has been spreading at unprecedented speed, and further spread within the countries being affected and to other adjacent or far way countries is considered inevitable due to the rapid emigration of infected individuals across the world. In this bioinformation, we discuss the mechanism of evolution of a new HxNy strain and the essential criteria for potentially breaking the outbreak of these extremely harmful and rapidly evolving viral strains in the near future by taking the recent H1N1 pandemic as a classical paradigm. 相似文献
994.
Musto H Naya H Zavala A Romero H Alvarez-Valín F Bernardi G 《Biochemical and biophysical research communications》2006,347(1):1-3
Two years ago, we showed that positive correlations between optimal growth temperature (T(opt)) and genome GC are observed in 15 out of the 20 families of prokaryotes we analyzed, thus indicating that "T(opt) is one of the factors that influence genomic GC in prokaryotes". Our results were disputed, but these criticisms were demonstrated to be mistaken and based on misconceptions. In a recent report, Wang et al. [H.C. Wang, E. Susko, A.J. Roger, On the correlation between genomic G+C content and optimal growth temperature in prokaryotes: data quality and confounding factors, Biochem. Biophys. Res. Commun. 342 (2006) 681-684] criticize our results by stating that "all previous simple correlation analyses of GC versus temperature have ignored the fact that genomic GC content is influenced by multiple factors including both intrinsic mutational bias and extrinsic environmental factors". This statement, besides being erroneous, is surprising because it applies in fact not to ours but to the authors' article. Here, we rebut the points raised by Wang et al. and review some issues that have been a matter of debate, regarding the influence of environmental factors upon GC content in prokaryotes. Furthermore, we demonstrate that the relationship that exists between genome size and GC level is valid for aerobic, facultative, and microaerophilic species, but not for anaerobic prokaryotes. 相似文献
995.
Lactococcus lactis carrying a DNA vaccine coding for the ESAT‐6 antigen increases IL‐17 cytokine secretion and boosts the BCG vaccine immune response 下载免费PDF全文
996.
Gradients of disturbance and environmental conditions shape coral community structure for south‐eastern Indian Ocean reefs 下载免费PDF全文
Jens Zinke James P. Gilmour Rebecca Fisher Marji Puotinen Joseph Maina Emily Darling Michael Stat Zoe T. Richards Timothy R. McClanahan Maria Beger Cordelia Moore Nicholas A. J. Graham Ming Feng Jean‐Paul A. Hobbs Scott N. Evans Stuart Field George Shedrawi Russ C. Babcock Shaun K. Wilson 《Diversity & distributions》2018,24(5):605-620
997.
Hironori Nishitsuji Ryuichi Sugiyama Makoto Abe Hiroshi Takaku 《The Journal of biological chemistry》2016,291(9):4754-4762
Here, we identify ATP1B3 and fibrillin-1 as novel BST-2-binding proteins. ATP1B3 depletion in HeLa cells (BST-2-positive cells), but not 293T cells (BST-2-negative cells), induced the restriction of HIV-1 production in a BST-2-dependent manner. In contrast, fibrillin-1 knockdown reduced HIV-1 production in 293T and HeLa cells in a BST-2-independent manner. Moreover, NF-κB activation was enhanced by siATP1B3 treatment in HIV-1- and HIV-1ΔVpu-infected HeLa cells. In addition, ATP1B3 silencing induced high level BST-2 expression on the surface of HeLa cells. These results indicate that ATP1B3 is a co-factor that accelerates BST-2 degradation and reduces BST-2-mediated restriction of HIV-1 production and NF-κB activation. 相似文献
998.
Development and evaluation of a multiplex PCR assay for rapid detection of toxigenic Vibrio cholerae O1 and O139 总被引:7,自引:0,他引:7
999.
Hubert E. Blum 《Journal of cellular and molecular medicine》2010,14(9):2257-2263
Molecular and cell biology have revolutionized not only diagnosis, therapy and prevention of human diseases but also greatly contributed to the understanding of their pathogenesis. Based on modern molecular and biochemical methods it is possible to identify on the one hand point mutations and single nucleotide polymorphisms. On the other hand, using high throughput array technologies, it is possible to analyse thousands of genes or gene products simultaneously, resulting in an individual gene or gene expression profile (signature). These data increasingly allow to define the individual risk for a given disease and to predict the individual prognosis of a disease as well as the efficacy of therapeutic strategies (individualized medicine). In the following sections some of the recent advances of predictive medicine and their clinical relevance will be addressed. 相似文献
1000.
Generation of a transgenic mouse model with chondrocyte-specific and tamoxifen-inducible expression of Cre recombinase 总被引:2,自引:0,他引:2
Chen M Lichtler AC Sheu TJ Xie C Zhang X O'Keefe RJ Chen D 《Genesis (New York, N.Y. : 2000)》2007,45(1):44-50
Postnatal cartilage development and growth are regulated by key growth factors and signaling molecules. To fully understand the function of these regulators, an inducible and chondrocyte-specific gene deletion system needs to be established to circumvent the perinatal lethality. In this report, we have generated a transgenic mouse model (Col2a1-CreER(T2)) in which expression of the Cre recombinase is driven by the chondrocyte-specific col2a1 promoter in a tamoxifen-inducible manner. To determine the specificity and efficiency of the Cre recombination, we have bred Col2a1-CreER(T2) mice with Rosa26R reporter mice. The X-Gal staining showed that the Cre recombination is specifically achieved in cartilage tissues with tamoxifen-induction. In vitro experiments of chondrocyte cell culture also demonstrate the 4-hydroxy tamoxifen-induced Cre recombination. These results demonstrate that Col2a1-CreER(T2) transgenic mice can be used as a valuable tool for an inducible and chondrocyte-specific gene deletion approach. 相似文献