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971.
[Ru(H)(CO)(PPh3)2(α/β-NaiR)](ClO4) (3, 4) are synthesized by the reaction of [Ru(H)(Cl)(CO)(PPh3)3] with 1-alkyl-2-(naphthyl-α/β-azo)imidazole (α-NaiR (3); β-NaiR (4)). One of the complexes [Ru(H)(CO)(PPh3)2(α-NaiMe)](ClO4) (3a) has been structurally established by X-ray diffraction study. Upon addition of Cl2 saturated in MeCN to 3 or 4 gives [Ru(Cl)(CO)(α/β-NaiR)(PPh3)2](ClO4) (for α-NaiR (5); β-NaiR (6)), without affecting metal oxidation state, which were characterized by spectroscopic measurements. The redox property of the complexes is examined by cyclic voltammetry. 相似文献
972.
Sharma P Singh N Sinha M Sharma S Perbandt M Betzel C Kaur P Srinivasan A Singh TP 《Journal of molecular biology》2008,378(4):923-932
The mammalian peptidoglycan recognition protein-S (PGRP-S) binds to peptidoglycans (PGNs), which are essential components of the cell wall of bacteria. The protein was isolated from the samples of milk obtained from camels with mastitis and purified to homogeneity and crystallized. The crystals belong to orthorhombic space group I222 with a = 87.0 Å, b = 101.7 Å and c = 162.3 Å having four crystallographically independent molecules in the asymmetric unit. The structure has been determined using X-ray crystallographic data and refined to 1.8 Å resolution. Overall, the structures of all the four crystallographically independent molecules are identical. The folding of PGRP-S consists of a central β-sheet with five β-strands, four parallel and one antiparallel, and three α-helices. This protein fold provides two functional sites. The first of these is the PGN-binding site, located on the groove that opens on the surface in the direction opposite to the location of the N terminus. The second site is implicated to be involved in the binding of non-PGN molecules, it also includes putative N-terminal segment residues (1-31) and helix α2 in the extended binding. The structure reveals a novel arrangement of PGRP-S molecules in which two pairs of molecules associate to form two independent dimers. The first dimer is formed by two molecules with N-terminal segments at the interface in which non-PGN binding sites are buried completely, whereas the PGN-binding sites of two participating molecules are fully exposed at the opposite ends of the dimer. In the second dimer, PGN-binding sites are buried at the interface while non-PGN binding sites are fully exposed at the opposite ends of the dimer. This form of dimeric arrangement is unique and seems to be aimed at enhancing the capability of the protein against specific invading bacteria. This mode of functional dimerization enhances efficiency and specificity, and is observed for the first time in the family of PGRP molecules. 相似文献
973.
Thakur M Chaba R Mondal AK Chakraborti PK 《The Journal of biological chemistry》2008,283(12):8023-8033
Eukaryotic type Ser/Thr protein kinases have recently been shown to regulate a variety of cellular functions in bacteria. PknA, a transmembrane Ser/Thr protein kinase from Mycobacterium tuberculosis, when constitutively expressed in Escherichia coli resulted in cell elongation and therefore has been thought to be regulating morphological changes associated with cell division. Bioinformatic analysis revealed that PknA has N-terminal catalytic, juxtamembrane, transmembrane, and C-terminal extracellular domains, like known eukaryotic type Ser/Thr protein kinases from other bacteria. To identify the minimum region capable of exhibiting phosphorylation activity of PknA, we created several deletion mutants. Surprisingly, we found that the catalytic domain itself was not sufficient for exhibiting phosphorylation ability of PknA. However, the juxtamembrane region together with the kinase domain was necessary for the enzymatic activity and thus constitutes the catalytic core of PknA. Utilizing this core, we deduce that the autophosphorylation of PknA is an intermolecular event. Interestingly, the core itself was unable to restore the cell elongation phenotype as manifested by the full-length protein in E. coli; however, its co-expression along with the C-terminal region of PknA can associate them in trans to reconstitute a functional protein in vivo. Therefore, these findings argue that the transmembrane and extracellular domains of PknA, although dispensable for phosphorylation activities, are crucial in responding to signals. Thus, our results for the first time establish the significance of different domains in a bacterial eukaryotic type Ser/Thr kinase for reconstitution of its functionality. 相似文献
974.
975.
Living systems are spectacular examples of spatiotemporally organized structures. During the development of complex organization
there is dynamic equilibrium between the local and global processes acting at the intra-and intercellular levels in multiple
space and time scales. Although in modelling studies such spatiotemporal systems can be described by different space-time
scales and at many organizational levels, the experimental quantities measured and predictions useful for practical applications
are at a macroscopic (coarser or averaged) level/scale; these are limited by the resolution of the measuring method and experimental
protocol. In this work, we address whether the spatiotemporal collective dynamics exhibited by a multiscale system can discriminate
between, or be borne out by, the coarse-grained and averaged measurements done at different spatial and temporal scales. Using
a simple model of a ring of cells, we show that measurements of both spatial and spatiotemporal average behaviour in this
multicellular ensemble can mask the variety of collective dynamics observed at other space-time scales, and exhibit completely
different behaviours. Such outcomes of measurements can lead to incomplete and incorrect understanding of physiological functions
and pathogenesis in multicell ensembles. 相似文献
976.
977.
Cypermethrin is the most widely used Type II pyrethroid pesticide because of its high effectiveness against target species and its low mammalian toxicity reported so far. It is a fast-acting neurotoxin and is known to cause free radical-mediated tissue damage. The present study investigates the genotoxic effects of cypermethrin in multiple organs (brain, kidney, liver, spleen) and tissues (bone marrow, lymphocytes) of the mouse, using the alkaline comet assay. Male Swiss albino mice were given 12.5, 25, 50, 100, 200 mg/kg BW of cypermethrin intraperitoneally, daily for 5 consecutive days. A statistically significant (p<0.05) dose-dependent increase in DNA damage was observed in all the organs assessed, as evident from the comet-assay parameters, viz., Olive tail moment (OTM; arbitrary unit), tail DNA (%) and tail length (microm). Brain showed maximum DNA damage followed by spleen>kidney>bone marrow>liver>lymphocytes, as evident by the OTM. Our data demonstrate that cypermethrin induces systemic genotoxicity in mammals as it causes DNA damage in vital organs like brain, liver, kidney, apart from that in the hematopoietic system. 相似文献
978.
Familial Danish dementia is a neurodegenerative disease which is a consequence of alterations in the BRI gene. The pathological signatures of the disease are cerebral amyloidolysis, parenchymal protein deposits and neuronal degeneration. Synthetic Danish dementia (ADan) peptides are capable of forming fibrillar assemblies in vitro at pH 4.8. However, the morphology of the aggregates formed depends greatly on the form of the peptides (oxidized or reduced). In addition to long slender assemblies (2-5 nm in diameter and several micrometers in length) we report ring-like or annular masses (8-9 nm in diameter and 1-2 mm in perimeter) in the case of the oxidized form of the peptides. The reduced forms mainly aggregate to produce granular heaps. The biophysical and kinetic characterization of the process of aggregation was carried out using different spectroscopic and imaging techniques. Neurotoxicity assays performed on both the forms reveal that the toxicity bears proportionality with the aggregate size. 相似文献
979.
Mitochondrial calcium signalling and cell death: approaches for assessing the role of mitochondrial Ca2+ uptake in apoptosis 总被引:6,自引:0,他引:6
Hajnóczky G Csordás G Das S Garcia-Perez C Saotome M Sinha Roy S Yi M 《Cell calcium》2006,40(5-6):553-560
Local Ca(2+) transfer between adjoining domains of the sarcoendoplasmic reticulum (ER/SR) and mitochondria allows ER/SR Ca(2+) release to activate mitochondrial Ca(2+) uptake and to evoke a matrix [Ca(2+)] ([Ca(2+)](m)) rise. [Ca(2+)](m) exerts control on several steps of energy metabolism to synchronize ATP generation with cell function. However, calcium signal propagation to the mitochondria may also ignite a cell death program through opening of the permeability transition pore (PTP). This occurs when the Ca(2+) release from the ER/SR is enhanced or is coincident with sensitization of the PTP. Recent studies have shown that several pro-apoptotic factors, including members of the Bcl-2 family proteins and reactive oxygen species (ROS) regulate the Ca(2+) sensitivity of both the Ca(2+) release channels in the ER and the PTP in the mitochondria. To test the relevance of the mitochondrial Ca(2+) accumulation in various apoptotic paradigms, methods are available for buffering of [Ca(2+)], for dissipation of the driving force of the mitochondrial Ca(2+) uptake and for inhibition of the mitochondrial Ca(2+) transport mechanisms. However, in intact cells, the efficacy and the specificity of these approaches have to be established. Here we discuss mechanisms that recruit the mitochondrial calcium signal to a pro-apoptotic cascade and the approaches available for assessment of the relevance of the mitochondrial Ca(2+) handling in apoptosis. We also present a systematic evaluation of the effect of ruthenium red and Ru360, two inhibitors of mitochondrial Ca(2+) uptake on cytosolic [Ca(2+)] and [Ca(2+)](m) in intact cultured cells. 相似文献
980.
Sindhu Radhakrishna Arup Ballav Goswami Anindya Sinha 《International journal of primatology》2006,27(4):971-982
We assessed the distribution and conservation status of Bengal slow lorises in Assam and Meghalaya in northeastern India. We surveyed forest reserves, plantations, tea estates, and areas bordering forests in 10 districts of the 2 states and sighted slow lorises in only 4 districts in Assam. Disturbances caused by tree felling, road kills by speeding vehicles, and trapping and hunting are the chief survival threats to the species. We emphasize immediate implementation of conservation measures to ensure the future of the species and recommend additional population surveys to define the distributional extent of Bengal slow lorises. 相似文献