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171.
Vanpé C Gaillard JM Kjellander P Mysterud A Magnien P Delorme D Van Laere G Klein F Liberg O Hewison AJ 《The American naturalist》2007,169(4):481-493
Identifying factors shaping secondary sexual traits is essential in understanding how their variation may influence male fitness. Little information is available on the allocation of resources to antler growth in territorial ungulates with low sexual size dimorphism. We investigated phenotypic and environmental factors affecting both absolute and relative antler size of male roe deer in three contrasting populations in France and Sweden. In the three populations, we found marked age-specific variation in antler size, with an increase in both absolute and relative antler size between yearling and prime-age stages, followed by a decrease (senescence) for males older than 7 years. Antler size increased allometrically with body mass. This increase was particularly strong for senescent males, suggesting the evolution of two reproductive tactics: heavy old males invested particularly heavily in antler growth (potentially remaining competitive for territories), whereas light old males grew small antlers (potentially abandoning territory defense). Finally, environmental conditions had little effect on antler size: only population density negatively affected absolute antler size in one of the three populations. Antler size may therefore provide an honest signal of male phenotypic quality in roe deer. We discuss the implications of these results in terms of territory tenure and mating competition. 相似文献
172.
Eriksson F Culp WD Massey R Egevad L Garland D Persson MA Pisa P 《Cancer immunology, immunotherapy : CII》2007,56(5):677-687
Within cancer research, phage display libraries have been widely used for the identification of tumor targeting peptides and
antibodies. Additionally, phages are known to be highly immunogenic; therefore we evaluated the immunotherapeutic potential
of tumor specific phages to treat established solid tumors in a mouse model of melanoma. We developed two tumor specific phages,
one derived from a peptide phage display library and one Fab expressing phage with known specificity, for the treatment of
mice bearing palpable B16-F10 or B16/A2Kb tumors. Therapy in B16-F10 tumor bearing mice with tumor specific phages was superior to treatment with non-tumor specific
phages and lead to delayed tumor growth and increased survival. In B16/A2Kb tumor bearing mice, therapy with tumor specific phages resulted in complete tumor regression and long-term survival in 50%
of the mice. Histological analysis of tumors undergoing treatment with tumor specific phages revealed that phage administration
induced a massive infiltration of polymorphonuclear neutrophils. Furthermore, phages induced secretion of IL-12 (p70) and
IFN-γ as measured in mouse splenocyte culture supernatants. These results demonstrate a novel, immunotherapeutic cancer treatment
showing that tumor specific phages can promote regression of established tumors by recruitment of inflammatory cells and induction
of Th1 cytokines. 相似文献
173.
A conserved modified wobble nucleoside (mcm5s2U) in lysyl-tRNA is required for viability in yeast 总被引:3,自引:0,他引:3 下载免费PDF全文
Transfer RNAs specific for Gln, Lys, and Glu from all organisms (except Mycoplasma) and organelles have a 2-thiouridine derivative (xm(5)s(2)U) as wobble nucleoside. These tRNAs read the A- and G-ending codons in the split codon boxes His/Gln, Asn/Lys, and Asp/Glu. In eukaryotic cytoplasmic tRNAs the conserved constituent (xm(5)-) in position 5 of uridine is 5-methoxycarbonylmethyl (mcm(5)). A protein (Tuc1p) from yeast resembling the bacterial protein TtcA, which is required for the synthesis of 2-thiocytidine in position 32 of the tRNA, was shown instead to be required for the synthesis of 2-thiouridine in the wobble position (position 34). Apparently, an ancient member of the TtcA family has evolved to thiolate U34 in tRNAs of organisms from the domains Eukarya and Archaea. Deletion of the TUC1 gene together with a deletion of the ELP3 gene, which results in the lack of the mcm(5) side chain, removes all modifications from the wobble uridine derivatives of the cytoplasmic tRNAs specific for Gln, Lys, and Glu, and is lethal to the cell. Since excess of the unmodified form of these three tRNAs rescued the double mutant elp3 tuc1, the primary function of mcm(5)s(2)U34 seems to be to improve the efficiency to read the cognate codons rather than to prevent mis-sense errors. Surprisingly, overexpression of the mcm(5)s(2)U-lacking tRNA(Lys) alone was sufficient to restore viability of the double mutant. 相似文献
174.
Summary. Trypanosomatids depend on spermidine for growth and survival. Consequently, enzymes involved in spermidine synthesis and utilization,
i.e. arginase, ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (AdoMetDC), spermidine synthase, trypanothione synthetase (TryS), and trypanothione reductase
(TryR), are promising targets for drug development. The ODC inhibitor α-difluoromethylornithine (DFMO) is about to become
a first-line drug against human late-stage gambiense sleeping sickness. Another ODC inhibitor, 3-aminooxy-1-aminopropane (APA),
is considerably more effective than DFMO against Leishmania promastigotes and amastigotes multiplying in macrophages. AdoMetDC inhibitors can cure animals infected with isolates from
patients with rhodesiense sleeping sickness and leishmaniasis, but have not been tested on humans. The antiparasitic effects
of inhibitors of polyamine and trypanothione formation, reviewed here, emphasize the relevance of these enzymes as drug targets.
By taking advantage of the differences in enzyme structure between parasite and host, it should be possible to design new
drugs that can selectively kill the parasites. 相似文献
175.
176.
Gorzsás A Stenlund H Persson P Trygg J Sundberg B 《The Plant journal : for cell and molecular biology》2011,66(5):903-914
Fourier‐transform infrared (FT‐IR) spectroscopy combined with microscopy enables chemical information to be acquired from native plant cell walls with high spatial resolution. Combined with a 64 × 64 focal plane array (FPA) detector, 4096 spectra can be simultaneously obtained from a 0.3 × 0.3 mm image; each spectrum represents a compositional and structural ‘fingerprint’ of all cell wall components. For optimal use and analysis of such a large amount of information, multivariate approaches are preferred. Here, FT‐IR microspectroscopy with FPA detection is combined with orthogonal projections to latent structures discriminant analysis (OPLS‐DA). This allows for: (i) the extraction of spectra from single cell types, (ii) identification and characterization of different chemotypes using the full spectral information, and (iii) further visualization of the pattern of identified chemotypes by multivariate imaging. As proof of concept, the chemotypes of Populus tremula xylem cell types are described. The approach revealed unknown features about chemical plasticity and patterns of lignin composition in wood fibers that would have remained hidden in the dataset with traditional data analysis. The applicability of the method to Arabidopsis xylem and its usefulness in mutant chemotyping is also demonstrated. The methodological approach is not limited to xylem tissues but can be applied to any plant organ/tissue also using other techniques such as Raman and UV microspectroscopy. 相似文献
177.
178.
Wang H Li ZY Liu Y Persson J Beyer I Möller T Koyuncu D Drescher MR Strauss R Zhang XB Wahl JK Urban N Drescher C Hemminki A Fender P Lieber A 《Nature medicine》2011,17(1):96-104
We have identified desmoglein-2 (DSG-2) as the primary high-affinity receptor used by adenoviruses Ad3, Ad7, Ad11 and Ad14. These serotypes represent key human pathogens causing respiratory and urinary tract infections. In epithelial cells, adenovirus binding of DSG-2 triggers events reminiscent of epithelial-to-mesenchymal transition, leading to transient opening of intercellular junctions. This opening improves access to receptors, for example, CD46 and Her2/neu, that are trapped in intercellular junctions. In addition to complete virions, dodecahedral particles (PtDds), formed by excess amounts of viral capsid proteins, penton base and fiber during viral replication, can trigger DSG-2-mediated opening of intercellular junctions as shown by studies with recombinant Ad3 PtDds. Our findings shed light on adenovirus biology and pathogenesis and may have implications for cancer therapy. 相似文献
179.
Strauss R Li ZY Liu Y Beyer I Persson J Sova P Möller T Pesonen S Hemminki A Hamerlik P Drescher C Urban N Bartek J Lieber A 《PloS one》2011,6(1):e16186
In our studies of ovarian cancer cells we have identified subpopulations of cells that are in a transitory E/M hybrid stage, i.e. cells that simultaneously express epithelial and mesenchymal markers. E/M cells are not homogenous but, in vitro and in vivo, contain subsets that can be distinguished based on a number of phenotypic features, including the subcellular localization of E-cadherin, and the expression levels of Tie2, CD133, and CD44. A cellular subset (E/M-MP) (membrane E-cadherin(low)/cytoplasmic E-cadherin(high)/CD133(high), CD44(high), Tie2(low)) is highly enriched for tumor-forming cells and displays features which are generally associated with cancer stem cells. Our data suggest that E/M-MP cells are able to differentiate into different lineages under certain conditions, and have the capacity for self-renewal, i.e. to maintain a subset of undifferentiated E/M-MP cells during differentiation. Trans-differentiation of E/M-MP cells into mesenchymal or epithelial cells is associated with a loss of stem cell markers and tumorigenicity. In vivo xenograft tumor growth is driven by E/M-MP cells, which give rise to epithelial ovarian cancer cells. In contrast, in vitro, we found that E/M-MP cells differentiate into mesenchymal cells, in a process that involves pathways associated with an epithelial-to-mesenchymal transition. We also detected phenotypic plasticity that was dependent on external factors such as stress created by starvation or contact with either epithelial or mesenchymal cells in co-cultures. Our study provides a better understanding of the phenotypic complexity of ovarian cancer and has implications for ovarian cancer therapy. 相似文献
180.