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The phase behavior of mixtures formed with palmitic acid (PA) and one of the following sterols (dihydrocholesterol, ergosterol, 7-dehydrocholesterol, stigmasterol and stigmastanol), in a PA/sterol molar ratio of 3/7, has been characterized by IR and 2H NMR spectroscopy at different pH. Our study shows that it is possible to form liquid-ordered (lo) lamellar phases with these binary non-phospholipid mixtures. The characterization of alkyl chain dynamics of PA in these systems revealed the large ordering effect of the sterols. It was possible to extrude these systems, using standard extrusion techniques, to form large unilamellar vesicles (LUVs), except in the case of ergosterol-containing mixture. The resulting LUVs displayed a very limited passive permeability consistent with the high sterol concentration. In addition, the stability of these PA/sterol self-assembled bilayers was also found to be pH-sensitive, therefore, potentially useful as nanovectors. By examining different sterols, we could establish some correlations between the structure of these bilayers and their permeability properties. The structure of the side chain at C17 of the sterol appears to play a prime role in the mixing properties with fatty acid. 相似文献
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Bingqing Xia Xurui Shen Yang He Xiaoyan Pan Feng-Liang Liu Yi Wang Feipu Yang Sui Fang Yan Wu Zilei Duan Xiaoli Zuo Zhuqing Xie Xiangrui Jiang Ling Xu Hao Chi Shuangqu Li Qian Meng Hu Zhou Yubo Zhou Xi Cheng Xiaoming Xin Lin Jin Hai-Lin Zhang Dan-Dan Yu Ming-Hua Li Xiao-Li Feng Jiekai Chen Hualiang Jiang Gengfu Xiao Yong-Tang Zheng Lei-Ke Zhang Jingshan Shen Jia Li Zhaobing Gao 《Cell research》2021,31(8):847
Cytokine storm and multi-organ failure are the main causes of SARS-CoV-2-related death. However, the origin of excessive damages caused by SARS-CoV-2 remains largely unknown. Here we show that the SARS-CoV-2 envelope (2-E) protein alone is able to cause acute respiratory distress syndrome (ARDS)-like damages in vitro and in vivo. 2-E proteins were found to form a type of pH-sensitive cation channels in bilayer lipid membranes. As observed in SARS-CoV-2-infected cells, heterologous expression of 2-E channels induced rapid cell death in various susceptible cell types and robust secretion of cytokines and chemokines in macrophages. Intravenous administration of purified 2-E protein into mice caused ARDS-like pathological damages in lung and spleen. A dominant negative mutation lowering 2-E channel activity attenuated cell death and SARS-CoV-2 production. Newly identified channel inhibitors exhibited potent anti-SARS-CoV-2 activity and excellent cell protective activity in vitro and these activities were positively correlated with inhibition of 2-E channel. Importantly, prophylactic and therapeutic administration of the channel inhibitor effectively reduced both the viral load and secretion of inflammation cytokines in lungs of SARS-CoV-2-infected transgenic mice expressing human angiotensin-converting enzyme 2 (hACE-2). Our study supports that 2-E is a promising drug target against SARS-CoV-2.Subject terms: Cell death, Molecular biology 相似文献
78.
Andrew W. Saxe Ji-Won Yoon Phillip Gorden Murray F. Brennan 《In vitro cellular & developmental biology. Plant》1982,18(10):884-890
Summary Dispersed cells from both fresh and cryopreserved human insulinoma have been maintained in cell culture. Initial yield of
viable cells was 50% for fresh and 25% for cryopreserved tissue. Viability of cells in culture was documented by increasing
numbers of cells (doubling time approximately 5 d initially and 2 d at the sixth subculture for both fresh and cryopreserved
tissue) and continued release of insulin over time (approximately 100 ng/ml per 105 cells at 10 d and 175 ng/ml per 105 cells at 30 d of culture for both fresh and cryopreserved tissue). Evidence that cells growing in culture were beta cells
was provided by: (a) recovery of intracellular and extracellular immunoreactive insulin (IRI), (b) electron microscopic morphology,
and (c) immunohistochemical staining. Cells from fresh insulinoma incubated with increasing concentrations of extracellular
glucose released increasing amounts of IRI up to approximately 15 mM glucose, which paralleled changes in plasma insulin obtained during a preoperative glucose tolerance test.
Under an Intergovernmental Personnel Act Exchange from the Department of Surgery, University of California, Davis, Sacramento
Medical Center. 相似文献
79.
Growth hormone induces two mRNA species of the serine protease inhibitor gene family in rat liver 总被引:2,自引:0,他引:2
In order to study the molecular actions of growth hormone on gene expression, we have cloned and characterized two unique, but related, cDNA sequences from rat liver, lambda Spi-1 and lambda Spi-2. These two cDNA sequences are complementary to rat hepatic mRNA species previously designated as Spots 3 and 20 when assayed by in vitro translation and two-dimensional gel electrophoresis. By Northern blot, the two mRNAs are both 1900 bases in length and growth hormone administered to hypophysectomized rats increases the levels of both of these mRNAs. In contrast, the combined administration of thyroxine, corticosterone, and dihydrotestosterone to hypophysectomized rats did not augment these mRNAs. The simultaneous administration of all four hormones resulted in a level greater than that observed for animals treated with growth hormone alone. Analysis of genomic DNA suggests the presence of two similar, but not identical, genes. DNA sequencing of lambda Spi-1 and lambda Spi-2 revealed that they were 90% homologous at the nucleotide level and 87% homologous at the amino acid sequence level. lambda Spi-2 has 78% homology with mouse contrapsin, 60% with human alpha 1-antichymotrypsin, and 51-55% with alpha 1-antitrypsins, all members of the serine protease inhibitor gene family. The nucleotide and deduced amino acid sequences of lambda Spi-1 and lambda Spi-2 which align with the reactive centers of known members of this family differ substantially from each other and from other members of the family. The difference in the reactive center suggests that the specificity or function of these proteins may differ from other members of serine protease inhibitor gene family. 相似文献
80.
Previous studies by us and others established that cell-cell adhesion is mediated by specific carbohydrate-to-carbohydrate
interaction (CCI). Those previous studies were based on various biochemical and biophysical approaches, including the use
of labeled glycosyl epitopes with fluorescent tag. However, these methods ideally require that the glycosyl epitope must be
fixed to a solid phase molecule, preferably with multivalency. The purpose of the present study is to establish a CCI process
using specific glycosyl residues conjugated to biotinylated diaminopyridine (BAP), and to observe: (i) clear occurrence of
homotypic CCI between “Os Fr.B” having 5–6 GlcNAc termini, vs. absence of such homotypic CCI between “Os Fr.1” having 2 GlcNAc termini; (ii) occurrence of heterotypic CCI between GM3
ganglioside and Os Fr.B, vs. absence of such heterotypic CCI between GM3 and Os Fr.1. Interaction between Os Fr.B-BAP conjugate and Os Fr.B-ceramide
mimetic (Os Fr.B-mCer) was demonstrated based on two experiments: (i) dose-dependent binding of Os Fr.B-BAP conjugate to polystyrene
plates coated with Os Fr.B-mCer was observed in the presence of bivalent cation, a prerequisite for all CCI processes, and
such binding was abolished by EDTA; (ii) binding between equal nanomolar Os Fr.B-BAP and Os Fr.B-mCer was inhibited by mM
concentration Os Fr.B without conjugate, in dose-dependent manner. Thus, cell adhesion processes based on homotypic CCI between
N-linked glycans having multiple GlcNAc termini, and heterotypic CCI between GM3 and such glycans, were clearly observed using
BAP conjugates of glycosyl epitopes. 相似文献