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71.
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73.
Lee H. Pratt Marie-Michèle Cordonnier-Pratt Bernard Hauser Michel Caboche 《Planta》1995,197(1):203-206
Tomato (Solanum lycopersicon L.) contains two B-type phytochrome genes (PHYB1 and PHYB2). Fragments of these two PHYB were cloned following amplification by the polymerase chain reaction of a portion of their relatively well conserved 5 coding regions. Polypeptides encoded by these gene fragments exhibit 90% sequence identity. These two PHYB are independently expressed in organ-specific fashion. In mature plants, PHYB2 mRNA is most abundant in fruit and PHYB1 mRNA in expanded leaves. A phylogenetic analysis fails to establish which tomato PHYB is orthologous to either Arabidopsis PHYB or PHYD, the latter being a second B-type phytochrome. Instead, this analysis indicates that following the divergence of the Solanaceae and Brassicaceae from one another, a PHYB gene duplicated independently in each lineage. Consequently, Arabidopsis PHYB mutants cannot be considered strictly equivalent to the tomato tri mutants, which appear to be mutated at the PHYB1 locus. Similarly, other putative PHYB mutants might not be equivalent to those described for Arabidopsis and tomato. This situation complicates efforts to determine PHYB function because there might be no one answer to this question.Abbreviations PCR
polymerase chain reaction
-
PHY
undesignated phytochrome gene
-
PHYA, PHYB, etc
phytochrome gene(s) of the A, B, etc. type
This research was supported by USDA NRICGP grant 93-00939 and by NATO travel grant CRG 931183. It was initiated when two of us (L.H.P., M.-M.C.-P.) spent a sabbatical year at the Institut National de la Recherche Agronomique in Versailles, France. L.H.P. gratefully acknowledges support provided by a senior guest fellowship from the Ministère de l'enseignement superieur et de la recherche during his stay in Versailles. L.H.P. and M.-M.C.-P thank all of their colleagues in Versailles for their warm hospitality and their willingness to share their expertise with us. We also thank Russell Malmberg, Richard Meagher and Robert Price for helpful discussions concerning the interpretation of molecular phylogenies. 相似文献
74.
基于右手螺旋短杆菌肽A离子通道模型,利用分子动力学计算机模拟方法研究了通道内离子K+,Na+,Li+与水分子的相关性. 相似文献
75.
Mini-mu derivatives carrying plasmid replicons can be used to clone genesin vivo. This method was adopted to generate phasmid clones which were later screened for their ability of restore nitrofurantoin
sensitivity of a nitrofuran-resistant host by eliciting nitroreductase activity. One phasmid-derived clone (pAJ101) resulted
in considerable increase in nitroreductase activity when introduced into a nitrofurantoin-resistant mutant ofEscherichia coli with reduced nitroreductase activity. Subsequently, a 1.8 kb fragment obtained from pAJ101 by partial digestion with 5au3A,
was subcloned into pUC18 to yield pAJ102. The nitroreductase activity attributable to pAJ102 was capable of reducing both
nitrofurantoin and nitrofurazone. The polypeptides encoded by pAJ102 were identified by the minicell method. A large, well-defined
band corresponding to 37 kDa and a smaller, less-defined band corresponding to 35 kDa were detected. Tnl000 mutagenesis was
used to delineate the coding segment of the 1.8 kb insert of pAJ102. A 0.8 kb stretch of DNA was shown to be part of the nitroreductase
gene. The gene was mapped at 19 min on theEscherichia coli linkage map. 相似文献
76.
Kergoat GJ Le Ru BP Genson G Cruaud C Couloux A Delobel A 《Molecular phylogenetics and evolution》2011,59(3):746-760
Though for a long time it was hypothesized that the extraordinary diversity of phytophagous insects was better explained by a synchronous pattern of co-diversification with plants, the results of recent studies have led to question this theory, suggesting that the diversification of insects occurred well after that of their hosts. In this study we address this issue by investigating the timing of diversification of a highly specialized group of seed beetles, which mostly feeds on legume plants from the tribe Indigofereae. To that purpose, a total of 130 specimens were sequenced for six genes and analyzed under a Bayesian phylogenetic framework. Based on the resulting trees we performed several analyses that allowed a better definition of the group boundaries and to investigate the status of several taxa through the use of molecular species delimitation analyses in combination with morphological evidences. In addition the evolution of host plant use was reconstructed and different molecular-dating approaches were carried out in order to assess the ages of several clades of interest. The resulting framework suggests a more ancient than previously thought origin for seed beetles, and a pattern of rapid host plant colonization. These findings call for further similar studies in other highly specialized groups of phytophagous insects. 相似文献
77.
Molecular dynamics of the FixJ receiver domain: movement of the beta4-alpha4 loop correlates with the in and out flip of Phe101 下载免费PDF全文
Roche P Mouawad L Perahia D Samama JP Kahn D 《Protein science : a publication of the Protein Society》2002,11(11):2622-2630
FixJ is a two-domain response regulator involved in nitrogen fixation in Sinorhizobium meliloti. Recent X-ray characterization of both the native (unphosphorylated) and the active (phosphorylated) states of the protein identify conformational changes of the beta4-alpha4 loop and the conserved residue Phe101 as the key switches in activation. These structures also allowed investigation of the transition between conformations of this two-component regulatory receiver domain by molecular dynamics simulations. The path for the conformational change was studied with a distance constraint directing the system from one state to the other. The simulations provide evidence for a correlation between the conformation of the beta4-alpha4 loop and the orientation of the residue Phe101. A model presenting the sequence of events during the activation/deactivation process is discussed. 相似文献
78.
Ruth Greussing Hermann Unterluggauer Rafal Koziel Andrea B. Maier Pidder Jansen-Dürr 《Journal of visualized experiments : JoVE》2012,(69)
Proteasome is the main intracellular organelle involved in the proteolytic degradation of abnormal, misfolded, damaged or oxidized proteins 1, 2. Maintenance of proteasome activity was implicated in many key cellular processes, like cell''s stress response 3, cell cycle regulation and cellular differentiation 4 or in immune system response 5. The dysfunction of the ubiquitin-proteasome system has been related to the development of tumors and neurodegenerative diseases 4, 6. Additionally, a decrease in proteasome activity was found as a feature of cellular senescence and organismal aging 7, 8, 9, 10. Here, we present a method to measure ubiquitin-proteasome activity in living cells using a GFP-dgn fusion protein. To be able to monitor ubiquitin-proteasome activity in living primary cells, complementary DNA constructs coding for a green fluorescent protein (GFP)–dgn fusion protein (GFP–dgn, unstable) and a variant carrying a frameshift mutation (GFP–dgnFS, stable 11) are inserted in lentiviral expression vectors. We prefer this technique over traditional transfection techniques because it guarantees a very high transfection efficiency independent of the cell type or the age of the donor. The difference between fluorescence displayed by the GFP–dgnFS (stable) protein and the destabilized protein (GFP-dgn) in the absence or presence of proteasome inhibitor can be used to estimate ubiquitin-proteasome activity in each particular cell strain. These differences can be monitored by epifluorescence microscopy or can be measured by flow cytometry. 相似文献
79.
Molecular dynamics simulations have become a popular and powerful technique to study lipids and membrane proteins. We present some general questions and issues that should be considered prior to embarking on molecular dynamics simulation studies of membrane proteins and review common simulation methods. We suggest a practical approach to setting up and running simulations of membrane proteins, and introduce two new (related) methods to embed a protein in a lipid bilayer. Both methods rely on placing lipids and the protein(s) on a widely spaced grid and then 'shrinking' the grid until the bilayer with the protein has the desired density, with lipids neatly packed around the protein. When starting from a grid based on a single lipid structure, or several potentially different lipid structures (method 1), the bilayer will start well-packed but requires more equilibration. When starting from a pre-equilibrated bilayer, either pure or mixed, most of the structure of the bilayer stays intact, reducing equilibration time (method 2). The main advantages of these methods are that they minimize equilibration time and can be almost completely automated, nearly eliminating one time consuming step in MD simulations of membrane proteins. 相似文献
80.
两种锦鸡和环颈雉线粒体DNA(mtDNA)的比较研究 总被引:12,自引:3,他引:12
本文以10种限制性内切酶分析雉科中环颈雉,红腹锦鸡和白腹锦鸡线粒体DNA(mtDNA)。雉属与锦鸡属之间的遗传距离P为0.076(0.067-0.085),红腹锦鸡与白腹锦鸡的P为0.012。推算雉属和锦鸡属的分化大约发生在3.8×10[6]年以前,红腹锦鸡与白腹锦鸡的分化大约在6×10[5]年以前。这些结果表明:1.在雉科系统发生中,雉属与锦鸡属是近缘的属;2.红腹锦鸡和白腹锦鸡的分化较晚,关系密切,可能只是两个亚种。 相似文献