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991.
Terry T. Isson Gordon D. Love Christopher L. Dupont Christopher T. Reinhard Alex J. Zumberge Dan Asael Bleuenn Gueguen John McCrow Ben C. Gill Jeremy Owens Robert H. Rainbird Alan D. Rooney Ming‐Yu Zhao Eva E. Stueeken Kurt O. Konhauser Seth G. John Timothy W. Lyons Noah J. Planavsky 《Geobiology》2018,16(4):341-352
The biogeochemical cycling of zinc (Zn) is intimately coupled with organic carbon in the ocean. Based on an extensive new sedimentary Zn isotope record across Earth's history, we provide evidence for a fundamental shift in the marine Zn cycle ~800 million years ago. We discuss a wide range of potential drivers for this transition and propose that, within available constraints, a restructuring of marine ecosystems is the most parsimonious explanation for this shift. Using a global isotope mass balance approach, we show that a change in the organic Zn/C ratio is required to account for observed Zn isotope trends through time. Given the higher affinity of eukaryotes for Zn relative to prokaryotes, we suggest that a shift toward a more eukaryote‐rich ecosystem could have provided a means of more efficiently sequestering organic‐derived Zn. Despite the much earlier appearance of eukaryotes in the microfossil record (~1700 to 1600 million years ago), our data suggest a delayed rise to ecological prominence during the Neoproterozoic, consistent with the currently accepted organic biomarker records. 相似文献
992.
Fall Lewis Stacey Benjamin S. Calverley Thomas Owens Thomas Thyer Kaitlin Griffiths Rhodri Phillips Rhodri Bailey Damian M. 《Journal of physiology and biochemistry》2023,79(1):35-46
Journal of Physiology and Biochemistry - While high-intensity interval training (HIIT) has emerged as a more time-efficient alternative to moderate-intensity steady-state exercise (MISS), the... 相似文献
993.
Shaun A Tauck Jesse R Olsen Jarrod RC Wilkinson Riley J Wedlake Kathleen C Davis James G Berardinelli 《Reproductive biology and endocrinology : RB&E》2010,8(1):89
Background
The physiological mechanism by which bulls stimulate resumption of ovarian cycling activity in postpartum, anovular, suckled cows after calving may involve the concurrent activation of the hypothalamic-hypophyseal-ovarian (HPO) axis and hypothalamic-hypophyseal-adrenal (HPA) axis. Thus, the objectives of this experiment were to determine if characteristics of temporal patterns of cortisol and luteinizing hormone (LH) in postpartum, anovular, beef cows are influenced by acute exposure to bulls. The null hypotheses were that daily, temporal characteristics of cortisol and LH concentration patterns do not differ between cows exposed acutely to bulls or steers. 相似文献994.
995.
996.
l‐glutamine Improves Skeletal Muscle Cell Differentiation and Prevents Myotube Atrophy After Cytokine (TNF‐α) Stress Via Reduced p38 MAPK Signal Transduction 下载免费PDF全文
997.
Chemical genetic identification of glutamine phosphoribosylpyrophosphate amidotransferase as the target for a novel bleaching herbicide in Arabidopsis 下载免费PDF全文
Walsh TA Bauer T Neal R Merlo AO Schmitzer PR Hicks GR Honma M Matsumura W Wolff K Davies JP 《Plant physiology》2007,144(3):1292-1304
A novel phenyltriazole acetic acid compound (DAS734) produced bleaching of new growth on a variety of dicotyledonous weeds and was a potent inhibitor of Arabidopsis (Arabidopsis thaliana) seedling growth. The phytotoxic effects of DAS734 on Arabidopsis were completely alleviated by addition of adenine to the growth media. A screen of ethylmethanesulfonate-mutagenized Arabidopsis seedlings recovered seven lines with resistance levels to DAS734 ranging from 5- to 125-fold. Genetic tests determined that all the resistance mutations were dominant and allelic. One mutation was mapped to an interval on chromosome 4 containing At4g34740, which encodes an isoform of glutamine phosphoribosylamidotransferase (AtGPRAT2), the first enzyme of the purine biosynthetic pathway. Sequencing of At4g34740 from the resistant lines showed that all seven contained mutations producing changes in the encoded polypeptide sequence. Two lines with the highest level of resistance (125-fold) contained the mutation R264K. The wild-type and mutant AtGPRAT2 enzymes were cloned and functionally overexpressed in Escherichia coli. Assays of the recombinant enzyme showed that DAS734 was a potent, slow-binding inhibitor of the wild-type enzyme (I(50) approximately 0.2 microm), whereas the mutant enzyme R264K was not significantly inhibited by 200 microm DAS734. Another GPRAT isoform in Arabidopsis, AtGPRAT3, was also inhibited by DAS734. This combination of chemical, genetic, and biochemical evidence indicates that the phytotoxicity of DAS734 arises from direct inhibition of GPRAT and establishes its utility as a new and specific chemical genetic probe of plant purine biosynthesis. The effects of this novel GPRAT inhibitor are compared to the phenotypes of known AtGPRAT genetic mutants. 相似文献
998.
O'Keefe SJ Mudgett JS Cupo S Parsons JN Chartrain NA Fitzgerald C Chen SL Lowitz K Rasa C Visco D Luell S Carballo-Jane E Owens K Zaller DM 《The Journal of biological chemistry》2007,282(48):34663-34671
The p38 MAP kinase signal transduction pathway is an important regulator of proinflammatory cytokine production and inflammation. Defining the roles of the various p38 family members, specifically p38alpha and p38beta, in these processes has been difficult. Here we use a chemical genetics approach using knock-in mice in which either p38alpha or p38beta kinase has been rendered resistant to the effects of specific inhibitors along with p38beta knock-out mice to dissect the biological function of these specific kinase isoforms. Mice harboring a T106M mutation in p38alpha are resistant to pharmacological inhibition of LPS-induced TNF production and collagen antibody-induced arthritis, indicating that p38beta activity is not required for acute or chronic inflammatory responses. LPS-induced TNF production, however, is still completely sensitive to p38 inhibitors in mice with a T106M point mutation in p38beta. Similarly, p38beta knock-out mice respond normally to inflammatory stimuli. These results demonstrate conclusively that specific inhibition of the p38alpha isoform is necessary and sufficient for anti-inflammatory efficacy in vivo. 相似文献
999.
Zehntner SP Bourbonnière L Moore CS Morris SJ Methot D St Jean M Lacasse E Hebb AL Robertson GS Durkin J Gillard JW Owens T 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(11):7553-7560
To understand how the balance between pro- and anti-apoptotic signals influences effector function in the immune system, we studied the X-linked inhibitor of apoptosis (XIAP), an endogenous regulator of cellular apoptosis. Real-time PCR showed increased XIAP expression in blood of mice with experimental autoimmune encephalomyelitis, correlating with disease severity. Daily administration (10 mg/kg/day i.p.) of a 19-mer antisense oligonucleotide specific for XIAP (ASO-XIAP) abolished disease-associated XIAP mRNA and protein expression, and given from day of onset, alleviated experimental autoimmune encephalomyelitis and prevented relapses. Prophylactic treatment also reduced XIAP expression and prevented disease. Random or 5-base mismatched ASO was not inhibitory, and ASO-XIAP did not affect T cell priming. In ASO-XIAP-treated animals, infiltrating cells and inflammatory foci were dramatically reduced within the CNS. Flow cytometry showed an 88-93% reduction in T cells. The proportion of TUNEL(+) apoptotic CD4(+) T cells in the CNS was increased from <1.6 to 26% in ASO-XIAP-treated mice, and the proportion of Annexin V-positive CD4(+) T cells in the CNS increased. Neurons and oligodendrocytes were not affected; neither did apoptosis increase in liver, where XIAP knockdown also occurred. ASO-XIAP increased susceptibility of T cells to activation-induced apoptosis in vitro. Our results identify XIAP as a critical controller of apoptotic susceptibility of effector T cell function. 相似文献
1000.
Sylvia T. Nurnberg Karen Cheng Azad Raiesdana Ramendra Kundu Clint L. Miller Juyong B. Kim Komal Arora Ivan Carcamo-Oribe Yiqin Xiong Nikhil Tellakula Vivek Nanda Nikitha Murthy William A. Boisvert Ulf Hedin Ljubica Perisic Silvia Aldi Lars Maegdefessel Milos Pjanic Gary K. Owens Michelle D. Tallquist Thomas Quertermous 《PLoS genetics》2015,11(5)