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141.
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
142.
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
143.
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
144.
145.
Le Naour F Charrin S Labas V Le Caer JP Boucheix C Rubinstein E 《Cancer immunology, immunotherapy : CII》2004,53(3):148-152
The tetraspanins form a family of about 30 molecules mainly expressed on the cell surface. They have been reported to be involved in many physiological or pathological processes, such as fertilization, immune response, development of the nervous system, and metastasis, as well as in infectious diseases (HCV, malaria, etc.). The tetraspanins may play a role as organizers of multimolecular complexes on the cell surface associating numerous proteins, the tetraspanin web. To better define the composition of the tetraspanin web, its characterization has been recently performed using mass spectrometry and proteomics. We report the proteomic analysis of tetraspanin complexes on B-lymphoid cells. Immunoprecipitation experiments were performed using mAbs directed against the tetraspanin CD9, and associated molecules were identified by MALDI-TOF (matrix assisted laser desorption ionization time of flight) mass spectrometry. This led to the identification of IgM as a novel component of the complexes. Thus, tetraspanins may connect several types of proteins with Ig domains, including HLA-DR, EWI-2, and IgM, that may play a role in immune responses.This work was presented at the first Cancer Immunology and Immunotherapy Summer School, 8–13 September 2003, Ionian Village, Bartholomeio, Peloponnese, Greece. 相似文献
146.
This article outlines recent advances in explaining hereditary deafness in molecular terms, focusing on isolated (i.e. nonsyndromic) hearing loss. The number of genes identified (36 to date) is growing rapidly. However, difficulties inherent in genetic linkage analysis, coupled with the possible involvement of environmental causes, have so far prevented the characterization of the main genes causative or predisposing to the late-onset forms of deafness. 相似文献
147.
148.
149.
Dagkessamanskaia A Moscoso M Hénard V Guiral S Overweg K Reuter M Martin B Wells J Claverys JP 《Molecular microbiology》2004,51(4):1071-1086
150.
Maamar H Valette O Fierobe HP Bélaich A Bélaich JP Tardif C 《Molecular microbiology》2004,51(2):589-598
Progress towards understanding the molecular basis of cellulolysis by Clostridium cellulolyticm was obtained through the study of the first cellulolysis defective mutant strain, namely cipCMut1. In this mutant, a 2 659 bp insertion element, disrupts the cipC gene at the sequence encoding the seventh cohesin of the scaffoldin CipC. cipC is the first gene in a large 'cel' gene cluster, encoding several enzymatic subunits of the cellulosomes, including the processive cellulase Cel48F, which is the major component. Physiological and biochemical studies showed that the mutant strain was affected in cellulosome synthesis and severely impaired in its ability to degrade crystalline cellulose. It produced small amounts of a truncated CipC protein (P120), which had functional cohesin domains and assembled complexes which did not contain any of the enzymes encoded by genes of the 'cel' cluster. The mutant cellulolytic system was mainly composed of three proteins designated P98, P105 and P125. Their N-termini did not match any of the known cellulase sequences from C. cellulolyticum. A large amount of entire CipC produced in the cipCMut1 strain by trans-complementation with plasmid pSOScipC did not restore the cellulolytic phenotype, in spite of the assembly of a larger amount of complexes. The complexes produced in the mutant and complemented strains contained at least 12 different dockerin-containing proteins encoded by genes located outside of the 'cel' cluster. The disturbances observed in the mutant and trans-complemented strains were the result of a strong polar effect resulting from the cipC gene disruption. In conclusion, this study provided genetic evidence that the cellulases encoded by the genes located in the 'cel' cluster are essential for the building of cellulosomes efficient in crystalline cellulose degradation. 相似文献