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排序方式: 共有3476条查询结果,搜索用时 15 毫秒
131.
Pannequin J Delaunay N Darido C Maurice T Crespy P Frohman MA Balda MS Matter K Joubert D Bourgaux JF Bali JP Hollande F 《Molecular cancer research : MCR》2007,5(11):1147-1157
Chronic alcohol consumption is associated with increased risk of gastrointestinal cancer. High concentrations of ethanol trigger mucosal hyperregeneration, disrupt cell adhesion, and increase the sensitivity to carcinogens. Most of these effects are thought to be mediated by acetaldehyde, a genotoxic metabolite produced from ethanol by alcohol dehydrogenases. Here, we studied the role of low ethanol concentrations, more likely to mimic those found in the intestine in vivo, and used intestinal cells lacking alcohol dehydrogenase to identify the acetaldehyde-independent biological effects of ethanol. Under these conditions, ethanol did not stimulate the proliferation of nonconfluent cells, but significantly increased maximal cell density. Incorporation of phosphatidylethanol, produced from ethanol by phospholipase D, was instrumental to this effect. Phosphatidylethanol accumulation induced claudin-1 endocytosis and disrupted the claudin-1/ZO-1 association. The resulting nuclear translocation of ZONAB was shown to mediate the cell density increase in ethanol-treated cells. In vivo, incorporation of phosphatidylethanol and nuclear translocation of ZONAB correlated with increased proliferation in the colonic epithelium of ethanol-fed mice and in adenomas of chronic alcoholics. Our results show that phosphatidylethanol accumulation after chronic ethanol exposure disrupts signals that normally restrict proliferation in highly confluent intestinal cells, thus facilitating abnormal intestinal cell proliferation. 相似文献
132.
133.
Fel Jean-Pierre Lacherez Catherine Bensetra Alaa Mezzache Sakina Béraud Eric Léonard Marc Allemand Denis Ferrier-Pagès Christine 《Coral reefs (Online)》2019,38(1):109-122
Coral Reefs - Ultraviolet (UV) filters and preservatives, which are common constituents of sunscreens and other cosmetics, are reported as a threat for coastal coral reef ecosystems; however, few... 相似文献
134.
Sarah Aherfi Djamal Brahim Belhaouari Lucile Pinault Jean-Pierre Baudoin Philippe Decloquement Jonatas Abrahao Philippe Colson Anthony Levasseur David C. Lamb Eric Chabriere Didier Raoult Bernard La Scola 《The ISME journal》2022,16(3):695
The discovery of Acanthamoeba polyphaga Mimivirus, the first isolated giant virus of amoeba, challenged the historical hallmarks defining a virus. Giant virion sizes are known to reach up to 2.3 µm, making them visible by optical microscopy. Their large genome sizes of up to 2.5 Mb can encode proteins involved in the translation apparatus. We have investigated possible energy production in Pandoravirus massiliensis. Mitochondrial membrane markers allowed for the detection of a membrane potential in purified virions and this was enhanced by a regulator of the tricarboxylic acid cycle but abolished by the use of a depolarizing agent. Bioinformatics was employed to identify enzymes involved in virion proton gradient generation and this approach revealed that eight putative P. massiliensis proteins exhibited low sequence identities with known cellular enzymes involved in the universal tricarboxylic acid cycle. Further, all eight viral genes were transcribed during replication. The product of one of these genes, ORF132, was cloned and expressed in Escherichia coli, and shown to function as an isocitrate dehydrogenase, a key enzyme of the tricarboxylic acid cycle. Our findings show for the first time that a membrane potential can exist in Pandoraviruses, and this may be related to tricarboxylic acid cycle. The presence of a proton gradient in P. massiliensis makes this virus a form of life for which it is legitimate to ask the question “what is a virus?”.Subject terms: Virology, Molecular evolution 相似文献
135.
136.
Jrme Pne Batrice Lagier Agns Rivier Pascal Chanez Jean-Pierre Vendrell Jean Bousquet 《Cell biology international》1993,17(3):353-358
Establishment of T cell clones derived from bronchial biopsies and peripheral blood from allergic asthmatics has shown that they secret a different IL-4 and IFN-γ pattern of cytokines, suggesting that the micro-environment of the bronchi may influence the phenotype of the T cells. 相似文献
137.
138.
This article discusses the growth of methanotrophic biofilms. Several independent biofilm growths scenarios involving different
inocula were examined. Biofilm growth, substrate removal and product formation were monitored throughout the experiments.
Based on the oxygen consumption it was concluded that heterotrophs and nitrifiers co-existed with methanotrophs in the biofilm.
Heterotrophic biomass grew on soluble polymers formed by the hydrolysis of dead biomass entrapped in the biofilm. Nitrifier
populations developed because of the presence of ammonia in the mineral medium. Based on these experimental results, the computer
program AQUASIM was used to develop a biological model involving methanotrophs, heterotrophs and nitrifiers. The modelling
of six independent growth experiments showed that stoichiometric and kinetic parameters were within the same order of magnitude.
Parameter estimation yielded an average maximum growth rate for methanotrophs, μm, of 1.5 ± 0.5 d−1, at 20 °C, a decay rate, bm, of 0.24 ± 0.1 d−1, a half saturation constant,
, of 0.06 ± 0.05 mg CH4/L, and a yield coefficient,
, of 0.57 ±: 0.04 g X/g CH4. In addition, a sensitivity analysis was performed on this model. It indicated that the most influential parameters were
those related to the biofilm (i.e. density; solid-volume fraction; thickness). This suggests that in order to improve the
model, further research regarding the biofilm structure and composition is needed. 相似文献
139.
Régis Millet Jean-François Goossens Karine Bertrand-Caumont Philippe Chavatte Raymond Houssin Jean-Pierre Hénichart 《Letters in Peptide Science》1999,6(4):221-233
Chemical modifications on the NK1 competitive antagonist L-732,138, with a view to creating a dual NK1/NK2 ligand, led to the tryptophan derivative 1 possessing the protected Gly-Leu sequence of the C-terminus of substance P and neurokinin A. Modifications in the nature of the carbamate function increased the selectivity for the NK1 receptor, whereas the inclusion of the indole moiety in -carboline or carbazole rings decreased the affinity for both receptors. Free indolylmethyl and Cbz carbamate groups were shown to be essential for NK2 affinity. 相似文献
140.
Kaleczyc J Timmermans JP Majewski M Lakomy M Scheuermann DW 《Histochemistry and cell biology》1999,111(3):217-228
Immunohistochemical studies have been performed to investigate the occurrence and coexistence of two catecholamine-synthesising
enzymes, tyrosine hydroxylase and dopamine-β-hydroxylase, and several neuropeptides, including neuropeptide Y, vasoactive
intestinal polypeptide, Leu5-enkephalin, somatostatin, calcitonin gene-related peptide and substance P, in nerve fibres supplying porcine accessory genital
glands, the seminal vesicles, prostate (body and the disseminated part) and bulbourethral glands. Three major populations
of nerve fibres supplying non-vascular elements of the glands have been distinguished (from the largest to the smallest one):
(1) noradrenergic fibres, the majority of which contain Leu5-enkephalin, neuropeptide Y or, to a lesser extent, somatostatin, (2) non-noradrenergic, putative cholinergic fibres containing
vasoactive intestinal polypeptide, neuropeptide Y and/or somatostatin and, (3) non-noradrenergic, presumably sensory fibres,
containing calcitonin gene-related peptide and substance P. Whilst the coexistence patterns within nerves supplying particular
glands are similar, the density of innervation varies between the organs. The innervation of the seminal vesicles and prostatic
body is more developed than that of the disseminated part of the prostate and bulbourethral glands. The majority of noradrenergic
fibres related to blood vessels contain neuropeptide Y only, while the non-noradrenergic nerves contain mainly vasoactive
intestinal polypeptide. The possible function and origin of particular nerve fibre populations are discussed.
Accepted: 16 November 1998 相似文献