全文获取类型
收费全文 | 5532篇 |
免费 | 476篇 |
国内免费 | 4篇 |
出版年
2023年 | 26篇 |
2022年 | 74篇 |
2021年 | 130篇 |
2020年 | 58篇 |
2019年 | 71篇 |
2018年 | 92篇 |
2017年 | 77篇 |
2016年 | 140篇 |
2015年 | 216篇 |
2014年 | 228篇 |
2013年 | 286篇 |
2012年 | 403篇 |
2011年 | 320篇 |
2010年 | 220篇 |
2009年 | 181篇 |
2008年 | 293篇 |
2007年 | 293篇 |
2006年 | 254篇 |
2005年 | 227篇 |
2004年 | 226篇 |
2003年 | 183篇 |
2002年 | 169篇 |
2001年 | 184篇 |
2000年 | 162篇 |
1999年 | 129篇 |
1998年 | 52篇 |
1997年 | 44篇 |
1996年 | 28篇 |
1995年 | 38篇 |
1994年 | 36篇 |
1993年 | 35篇 |
1992年 | 92篇 |
1991年 | 77篇 |
1990年 | 80篇 |
1989年 | 84篇 |
1988年 | 61篇 |
1987年 | 62篇 |
1986年 | 68篇 |
1985年 | 68篇 |
1984年 | 54篇 |
1983年 | 49篇 |
1982年 | 40篇 |
1981年 | 28篇 |
1980年 | 31篇 |
1979年 | 42篇 |
1978年 | 31篇 |
1976年 | 27篇 |
1975年 | 27篇 |
1974年 | 34篇 |
1973年 | 36篇 |
排序方式: 共有6012条查询结果,搜索用时 187 毫秒
841.
Biological hydrogen (H2) production by dark and photo-fermentative organisms is a promising area of research for generating bioenergy. A large number of organisms have been widely studied for producing H2 from diverse feeds, both as pure and as mixed cultures. However, their H2 producing efficiencies have been found to vary (from 3 to 8 mol/mol hexose) with physiological conditions, type of organisms and composition of feed (starchy waste from sweet potato, wheat, cassava and algal biomass). The present review deals with the possibilities of enhancing H2 production by integrating metabolic pathways of different organisms-dark fermentative bacteria (from cattle dung, activated sludge, Caldicellulosiruptor, Clostridium, Enterobacter, Lactobacillus, and Vibrio) and photo-fermentative bacteria (such as Rhodobacter, Rhodobium and Rhodopseudomonas). The emphasis has been laid on systems which are driven by undefined dark-fermentative cultures in combination with pure photo-fermentative bacterial cultures using biowaste as feed. Such an integrative approach may prove suitable for commercial applications on a large scale. 相似文献
842.
Mirko Rivara Manoj K. Patel Laura Amori Valentina Zuliani 《Bioorganic & medicinal chemistry letters》2012,22(20):6401-6404
We have synthesized and evaluated a series of 1,4-disubstituted-triazole derivatives for inhibition of the rat NaV1.6 sodium channel isoform, an isoform thought to play an important role in controlling neuronal firing. Starting from a series of 2,4(1H)-diarylimidazoles previously published, we decided to extend the SAR study by replacing the imidazole with a different heterocyclic scaffold and by varying the aryl substituents on the central aromatic ring. The 1,4-disubstituted 1,2,3-triazoles were prepared employing the copper-catalyzed azide–alkyne cycloaddition (CuAAC). Many of the new molecules were able to block the rNav1.6 currents at 10 μM by over 20%, displaying IC50 values ranging in the low micromolar, thus indicating that triazole can efficiently replace the central heterocyclic core. Moreover, the introduction of a long chain at C4 of the central triazole seems beneficial for increased rNav1.6 current block, whereas the length of N1 substituent seems less crucial for inhibition, as long as a phenyl ring is not direcly connected to the triazole. These results provide additional information on the structural features necessary for block of the voltage-gated sodium channels. These new data will be exploited in the preparation of new compounds and could result in potentially useful AEDs. 相似文献
843.
844.
Marc Kschonsak Lionel Rougé Christopher P. Arthur Ho Hoangdung Nidhi Patel Ingrid Kim Matthew C. Johnson Edward Kraft Alexis L. Rohou Avinash Gill Nadia Martinez-Martin Jian Payandeh Claudio Ciferri 《Cell》2021,184(5):1232-1244.e16
- Download : Download high-res image (205KB)
- Download : Download full-size image
845.
846.
Ilker Kudret Sariyer Nana Merabova Prem Kumer Patel Tijana Knezevic Alessandra Rosati Maria C. Turco Kamel Khalili 《PloS one》2012,7(9)
JC virus, JCV, is a human neurotropic polyomavirus whose replication in glial cells causes the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). In addition, JCV possesses oncogenic activity and expression of its transforming protein, large T-antigen (T-Ag), in several experimental animals induces tumors of neural origin. Further, the presence of JCV DNA and T-Ag have been repeatedly observed in several human malignant tissues including primitive neuroectodermal tumors and glioblastomas. Earlier studies have demonstrated that Bag3, a member of the Bcl-2-associated athanogene (Bag) family of proteins, which is implicated in autophagy and apoptosis, is downregulated upon JCV infection of glial cells and that JCV T-Ag is responsible for suppressing the activity of the BAG3 promoter. Here, we investigated the possible impact of Bag3 on T-Ag expression in JCV-infected human primary glial cells as well as in cells derived from T-Ag-induced medulloblastoma in transgenic animals. Results from these studies revealed that overexpression of Bag3 drastically decreases the level of T-Ag expression by inducing the autophagic degradation of the viral protein. Interestingly, this event leads to the inhibition of JCV infection of glial cells, suggesting that the reduced levels of T-antigen seen upon the overexpression of Bag3 has a biological impact on the viral lytic cycle. Results from protein-protein interaction studies showed that T-Ag and Bag3 physically interact with each other through the zinc-finger of T-Ag and the proline rich domains of Bag3, and this interaction is important for the autophagic degradation of T-Ag. Our observations open a new avenue of research for better understanding of virus-host interaction by investigating the interplay between T-Ag and Bag3, and their impact on the development of JCV-associated diseases. 相似文献
847.
T. P. Patel M. A. Chauncey T. A. Millican M. A.W. Eaton 《Nucleosides, nucleotides & nucleic acids》2013,32(1-2)
Abstract An equimolar solution of aldoxime and tetramethylguanidine at 70°C cleaves all base labile protecting groups from oligonucleotides. 相似文献
848.
S. Parekh A. Patel C. J. McNeal J. Nagyvary 《Nucleosides, nucleotides & nucleic acids》2013,32(1):91-98
Abstract This communication describes the synthesis of 5′-deoxy-5′-chloro-3′-(2-thio-1,3,2-dioxaphosphorinanyl)thymidine, N4,2′,3′-triacetyl-5′-(2-thio-1,3,2-dioxaphosphorinanyl)-1-β-D-arabinosyl-cytosine and N4-acetyl-5′-(2-thio-1,3,2-dioxaphosphorinanyl)-1-β-D-arabinosylcytosine. 相似文献
849.
850.
Li-Fen Liu Wen-Jun Shen Masami Ueno Shailja Patel Salman Azhar Fredric B. Kraemer 《PloS one》2013,8(8)
This study aimed to characterize and compare the effects of obesity on gene expression profiles in two distinct adipose depots, epididymal and bone marrow, at two different ages in mice. Alterations in gene expression were analyzed in adipocytes isolated from diet-induced obese (DIO) C57BL/6J male mice at 6 and 14 months of age and from leptin deficient mice (ob/ob) at 6 months of age using microarrays. DIO affected gene expression in both depots at 6 and 14 months, but more genes were altered in epididymal than bone marrow adipocytes at each age and younger mice displayed more changes than older animals. In epididymal adipocytes a total of 2789 (9.6%) genes were differentially expressed at 6-months with DIO, whereas 952 (3.3%) were affected at 14-months. In bone marrow adipocytes, 347 (1.2%) genes were differentially expressed at 6-months with DIO, whereas only 189 (0.66%) were changed at 14-months. 133 genes were altered by DIO in both fat depots at 6-months, and 37 genes at 14-months. Only four genes were altered in both depots at both ages with DIO. Bone marrow adipocytes are less responsive to DIO than epididymal adipocytes and the response of both depots to DIO declines with age. This loss of responsiveness with age is likely due to age-associated changes in expression of genes related to adipogenesis, inflammation and mitochondrial function that are similar to and obscure the changes commonly associated with DIO. Patterns of gene expression were generally similar in epididymal adipocytes from ob/ob and DIO mice; however, several genes were differentially expressed in bone marrow adipocytes from ob/ob and DIO mice, perhaps reflecting the importance of leptin signaling for bone metabolism. In conclusion, obesity affects age-associated alterations in gene expression in both epididymal and bone marrow adipocytes regardless of diet or genetic background. 相似文献