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991.
992.
Thi Phi Oanh Nguyen Damian E. Helbling Karolien Bers Tekle Tafese Fida Ruddy Wattiez Hans-Peter E. Kohler Dirk Springael René De Mot 《Applied microbiology and biotechnology》2014,98(19):8235-8252
The widespread agricultural application of carbofuran and concomitant contamination of surface and ground waters has raised health concerns due to the reported toxic effects of this insecticide and its degradation products. Most bacteria that degrade carbofuran only perform partial degradation involving carbamate hydrolysis without breakdown of the resulting phenolic metabolite. The capacity to mineralize carbofuran beyond the benzofuran ring has been reported for some bacterial strains, especially sphingomonads, and some common metabolites, including carbofuran phenol, were identified. In the current study, the catabolism of carbofuran by Novosphingobium sp. KN65.2 (LMG 28221), a strain isolated from a carbofuran-exposed Vietnamese soil and utilizing the compound as a sole carbon and nitrogen source, was studied. Several KN65.2 plasposon mutants with diminished or abolished capacity to degrade and mineralize carbofuran were generated and characterized. Metabolic profiling of representative mutants revealed new metabolic intermediates, in addition to the initial hydrolysis product carbofuran phenol. The promiscuous carbofuran-hydrolyzing enzyme Mcd, which is present in several bacteria lacking carbofuran ring mineralization capacity, is not encoded by the Novosphingobium sp. KN65.2 genome. An alternative hydrolase gene required for this step was not identified, but the constitutively expressed genes of the unique cfd operon, including the oxygenase genes cfdC and cfdE, could be linked to further degradation of the phenolic metabolite. A third involved oxygenase gene, cfdI, and the transporter gene cftA, encoding a TonB-dependent outer membrane receptor with potential regulatory function, are located outside the cfd cluster. This study has revealed the first dedicated carbofuran catabolic genes and provides insight in the early steps of benzofuran ring degradation. 相似文献
993.
994.
995.
Myszka A Karpinski P Slezak R Czemarmazowicz H Stembalska A Gil J Laczmanska I Bednarczyk D Szmida E Sasiadek MM 《Journal of applied genetics》2011,52(2):185-191
CHEK2 gen encodes cell cycle checkpoint kinase 2 that participates in the DNA repair pathway, cell cycle regulation and apoptosis.
Mutations in CHEK2 gene may result in kinase inactivation or reduce both catalytic activity and capability of binding other proteins. Some studies
indicate that alterations in CHEK2 gene confers increase the risk of breast cancer and some other malignancies, while the results of other studies are inconclusive.
Thus the significance of CHEK2 mutations in aetiology of breast cancer is still debatable. The aim of our study was to evaluate the relationship between
the breast/ovarian cancer and CHEK2 variants by: i) the analysis of the frequency of selected CHEK2 variants in breast and ovarian cancer patients compared to the controls; ii) evaluation of relationships between the certain CHEK2 variants and clinico-histopathological and pedigree data. The study was performed on 284 breast cancer patients, 113 ovarian
cancer patients and 287 healthy women. We revealed the presence of 430T > C, del5395 and IVS2 + 1G > A variants but not 1100delC
in individuals from both study and control groups. We did not observe significant differences between cancer patients and
controls neither in regard to the frequency nor to the type of CHEK2 variants. We discussed the potential application of CHEK2 variants in the evaluation of breast and ovarian cancer predisposition. 相似文献
996.
There is much uncertainty as to how fungal disease is diagnosed and characterized in patients with cystic fibrosis (CF). A 19-question anonymous electronic questionnaire was developed and distributed to ascertain current practice in clinical microbiology laboratories providing a fungal laboratory service to CF centres in the UK. Analyses of responses identified the following: (1) current UK laboratory practice, in general, follows the current guidelines, but the scope and diversity of what is currently being delivered by laboratories far exceeds what is detailed in the guidelines; (2) there is a lack of standardization of fungal tests amongst laboratories, outside of the current guidelines; (3) both the UK CF Trust Laboratory Standards for Processing Microbiological Samples from People with Cystic Fibrosis and the US Cumulative Techniques and Procedures in Clinical Microbiology (Cumitech) Guidelines 43 Cystic Fibrosis Microbiology need to be updated to reflect both new methodological innovations, as well as better knowledge of fungal disease pathophysiology in CF; (4) there is a need for clinical medicine to decide upon a stratification strategy for the provision of new fungal assays that will add value to the physician in the optimal management of CF patients; (5) there is also a need to rationale what assays should be performed at local laboratory level and those which are best served at National Mycology Reference Laboratory level; and (6) further research is required in developing laboratory assays, which will help ascertain the clinical importance of ‘old’ fungal pathogens, as well as ‘emerging’ fungal pathogens. 相似文献
997.
998.
999.
The folding of many proteins depends on the assistance of chaperonins like GroEL and GroES and involves the enclosure of substrate proteins inside an internal cavity that is formed when GroES binds to GroEL in the presence of ATP. Precisely how assembly of the GroEL-GroES complex leads to substrate protein encapsulation and folding remains poorly understood. Here we use a chemically modified mutant of GroEL (EL43Py) to uncouple substrate protein encapsulation from release and folding. Although EL43Py correctly initiates a substrate protein encapsulation reaction, this mutant stalls in an intermediate allosteric state of the GroEL ring, which is essential for both GroES binding and the forced unfolding of the substrate protein. This intermediate conformation of the GroEL ring possesses simultaneously high affinity for both GroES and non-native substrate protein, thus preventing escape of the substrate protein while GroES binding and substrate protein compaction takes place. Strikingly, assembly of the folding-active GroEL-GroES complex appears to involve a strategic delay in ATP hydrolysis that is coupled to disassembly of the old, ADP-bound GroEL-GroES complex on the opposite ring. 相似文献
1000.
Sublimons are substoichiometric DNA molecules which are generated by recombinations across short repeats, located in main
mitochondrial genome of plants. Since short repeats are believed to recombine irreversibly and to be usually inactive, it
is unknown how substoichiometric sequences are maintained. Occasionally, sublimons are amplified during substoichiometric
shifting (SSS) and take the role of the main genome. Using the Phaseolus vulgaris system, we have addressed the questions concerning accumulation of sublimons, the role of recombination in their maintenance
and selective amplification during SSS. We found that sublimons accompanied by parental recombination sequences were maintained
by constant recombination across a short 314-bp repeat. The abundance of these sublimons was three orders of magnitude higher
than accumulation of those which could not be maintained by recombination because their parental forms were absent from the
main genome. As expected for active recombination, two recombination-derived sublimons were equimolar and so were their parental
forms. One parental and one substoichiometric form shared the A/C polymorphism indicating their frequent inter-conversion.
Only the C variant of the sublimon was amplified during substoichiometric shift implying strong selection of DNA molecules
operating during SSS. 相似文献