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51.
In order to determine quantitatively the free radical content and its changes affected by additives using spin trapping under in vivo conditions, an approach is suggested carrying out experiments in a completely mixed open system (CMOS). Measurements have been carried out for a chemical oxidation process as a model system, and analysis of products and of the spin trap was extended by kinetic ESR spectrometry of the spin adducts. Since in a CMOS differential equations of accumulation of all species can be transformed into algebraic expressions using available rate constants for the formation of the spin adducts, corresponding concentrations of free radicals have been calculated. In addition, it has been established that triplet excited photosensitizers have a double effect: increasing the rate of initiation by decomposing hydroperoxide-type compounds and inhibiting the overall process by interactions with free radicals. Results indicate that by changing the "reaction vessel" the method can be applied for ex vivo and in vivo systems. 相似文献
52.
Schwabe TM Gloddek K Schluesener D Kruip J 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2003,786(1-2):45-59
The gene products Ycf3 (hypothetical chloroplast open reading frame) and BtpA (biogenesis of thylakoid protein) are thought to be involved in the biogenesis of the membrane protein complex photosystem I (PSI) from Synechocystis PCC 6803. PSI consists of 12 different subunits and binds more than 100 cofactors, making it a model protein to study different aspects of membrane protein biogenesis. For a detailed biophysical characterization of Ycf3 and BtpA pure proteins must be available in sufficient quantities. Therefore we cloned the corresponding genes into expression vectors. To facilitate purification we created His-tagged versions of Ycf3 and BtpA in addition to the unmodified forms. Immobilized metal affinity chromatography (IMAC) yielded His-tagged proteins which were used for the production of antibodies. Purification strategies for non-tagged proteins could also be established: Ycf3 could be purified in soluble form using a two-step purification in which ammonium sulfate precipitation was combined with anion-exchange chromatography (IEC). BtpA had to be purified from inclusion bodies by two-consecutive IEC steps under denaturing conditions. An optimized refolding protocol was established that yielded pure BtpA. In all cases, MALDI-TOF peptide mass fingerprinting (PMF) was used to confirm protein identity. Initially, size exclusion chromatography and CD-spectroscopy were used for biophysical characterization of the proteins. Both Ycf3 and BtpA show homo-oligomerization in vitro. In summary, purification protocols for Ycf3 and BtpA have been designed that yield pure proteins which can be used to probe the molecular function of these proteins for membrane protein biogenesis. 相似文献
53.
The zebrafish van gogh mutation disrupts tbx1, which is involved in the DiGeorge deletion syndrome in humans 总被引:6,自引:0,他引:6
Piotrowski T Ahn DG Schilling TF Nair S Ruvinsky I Geisler R Rauch GJ Haffter P Zon LI Zhou Y Foott H Dawid IB Ho RK 《Development (Cambridge, England)》2003,130(20):5043-5052
The van gogh (vgo) mutant in zebrafish is characterized by defects in the ear, pharyngeal arches and associated structures such as the thymus. We show that vgo is caused by a mutation in tbx1, a member of the large family of T-box genes. tbx1 has been recently suggested to be a major contributor to the cardiovascular defects in DiGeorge deletion syndrome (DGS) in humans, a syndrome in which several neural crest derivatives are affected in the pharyngeal arches. Using cell transplantation studies, we demonstrate that vgo/tbx1 acts cell autonomously in the pharyngeal mesendoderm and influences the development of neural crest-derived cartilages secondarily. Furthermore, we provide evidence for regulatory interactions between vgo/tbx1 and edn1 and hand2, genes that are implicated in the control of pharyngeal arch development and in the etiology of DGS. 相似文献
54.
Electron transport system (ETS) activity was measured in Chirocephalus croaticus from the intermittent lake, Petelinjsko Jezero. The ETS activities were measured at 5, 10, 15, 20, and 25 °C, and were studied separately in juveniles, females and males. Juveniles had significantly higher activity than adults at a standard temperature of 20 °C. The mass-specific ETS activity decreased with increasing size of the animals; the value b was 0.787. Respiration rates (R) were determined at 20 °C and the ratio ETS/R (±standard deviation) for C. croaticus was 1.43±0.46 (n=38). ETS activity increased with temperature. Females had higher Q10 than males in higher temperature range (t-test; t=2.50; d.f.=8; p<0.05). Activation energy Ea was higher for females than males (t-test; t=2.35; d.f.=8; p<0.05). Females exhibited lower ETS activity than males over the lower temperature range, but their ETS could function more efficient at higher temperature. 相似文献
55.
Professor Mirko Drazen Grmek (Krapina 1924--Paris 2000) was one of the most prominent Croatian scientists. Work in history of science directed him to the crossroads of various fields placing his approach in anthropological perspective. Two models will serve as illustrations of his main theories. The historical reconstruction of scientific discovery (mostly on examples of 17th century) will be presented as well as Grmek's ideas on a concept of disease. The introduction of the term "memoricide" within his activities during aggression on Croatia is mentioned. 相似文献
56.
Antimicrobial and Cytotoxic Activity of Extracts of Ferula heuffelii Griseb. ex Heuff. and Its Metabolites
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Ivan Pavlović Silvana Petrović Marina Milenković Tatjana Stanojković Dejan Nikolić Aleksej Krunić Marjan Niketić 《化学与生物多样性》2015,12(10):1585-1594
The antimicrobial and cytotoxic activities of isolates (CHCl3 and MeOH extracts and selected metabolites) obtained from the underground parts of the Balkan endemic plant Ferula heuffelii Griseb . ex Heuff . were assessed. The CHCl3 and MeOH extracts exhibited moderate antimicrobial activity, being more pronounced against Gram‐positive than Gram‐negative bacteria, especially against Staphylococcus aureus (MIC=12.5 μg/ml for both extracts) and Micrococcus luteus (MIC=50 and 12.5 μg/ml, resp.). Among the tested metabolites, (6E)‐1‐(2,4‐dihydroxyphenyl)‐3,7,11‐trimethyl‐3‐vinyldodeca‐6,10‐dien‐1‐one ( 2 ) and (2S*,3R*)‐2‐[(3E)‐4,8‐dimethylnona‐3,7‐dien‐1‐yl]‐2,3‐dihydro‐7‐hydroxy‐2,3‐dimethylfuro[3,2‐c]coumarin ( 4 ) demonstrated the best antimicrobial activity. Compounds 2 and 4 both strongly inhibited the growth of M. luteus (MIC=11.2 and 5.2 μM , resp.) and Staphylococcus epidermidis (MIC=22.5 and 10.5 μM , resp.) and compound 2 additionally also the growth of Bacillus subtilis (MIC=11.2 μM ). The cytotoxic activity of the isolates was tested against three human cancer cell lines, viz., cervical adenocarcinoma (HeLa), chronic myelogenous leukemia (K562), and breast cancer (MCF‐7) cells. The CHCl3 extract exhibited strong cytotoxic activity against all cell lines (IC50<11.0 μg/ml). All compounds strongly inhibited the growth of the K562 and HeLa cell lines. Compound 4 exhibited also a strong activity against the MCF‐7 cell line, comparable to that of cisplatin (IC50=22.32±1.32 vs. 18.67±0.75μM ). 相似文献
57.
Indrikis Krams Sanita Kecko Katariina Kangassalo Fhionna R. Moore Eriks Jankevics Inna Inashkina Tatjana Krama Vilnis Lietuvietis Laila Meija Markus J. Rantala 《Insect Science》2015,22(3):431-439
The resources available to an individual in any given environment are finite, and variation in life history traits reflect differential allocation of these resources to competing life functions. Nutritional quality of food is of particular importance in these life history decisions. In this study, we tested trade‐offs among growth, immunity and survival in 3 groups of greater wax moth (Galleria mellonella) larvae fed on diets of high and average nutritional quality. We found rapid growth and weak immunity (as measured by encapsulation response) in the larvae of the high‐energy food group. It took longer to develop on food of average nutritional quality. However, encapsulation response was stronger in this group. The larvae grew longer in the low‐energy food group, and had the strongest encapsulation response. We observed the highest survival rates in larvae of the low‐energy food group, while the highest mortality rates were observed in the high‐energy food group. A significant negative correlation between body mass and the strength of encapsulation response was found only in the high‐energy food group revealing significant competition between growth and immunity only at the highest rates of growth. The results of this study help to establish relationships between types of food, its nutritional value and life history traits of G. mellonella larvae. 相似文献
58.
Marko Dragas Igor Koncar Dragan Opacic Nikola Ilic Zivan Maksimovic Miroslav Markovic Marko Ercegovac Tatjana Simic Marija Pljesa-Ercegovac Lazar Davidovic 《PloS one》2015,10(4)
Objective
To evaluate the changes in serum neuron specific enolase and protein S-100B, after carotid endarterectomy performed using the conventional technique with routine shunting and patch closure, or eversion technique without the use of shunt.Materials and Methods
Prospective non-randomized study included 43 patients with severe (>80%) carotid stenosis undergoing carotid endarterectomy in regional anesthesia. Patients were divided into two groups: conventional endarterectomy with routine use of shunt and Dacron patch (csCEA group) and eversion endarterectomy without the use of shunt (eCEA group). Protein S-100B and NSE concentrations were measured from peripheral blood before carotid clamping, after declamping and 24 hours after surgery.Results
Neurologic examination and brain CT findings on the first postoperative day did not differ from preoperative controls in any patients. In csCEA group, NSE concentrations decreased after declamping (P<0.01), and 24 hours after surgery (P<0.01), while in the eCEA group NSE values slightly increased (P=ns), accounting for a significant difference between groups on the first postoperative day (P=0.006). In both groups S-100B concentrations significantly increased after declamping (P<0.05), returning to near pre-clamp values 24 hours after surgery (P=ns). Sub-group analysis revealed significant decline of serum NSE concentrations in asymptomatic patients shunted during surgery after declamping (P<0.05) and 24 hours after surgery (P<0.01), while no significant changes were noted in non-shunted patients (P=ns). Decrease of NSE serum levels was also found in symptomatic patients operated with the use of shunt on the first postoperative day (P<0.05). Significant increase in NSE serum levels was recorded in non-shunted symptomatic patients 24 hours after surgery (P<0.05).Conclusion
Variations of NSE concentrations seemed to be influenced by cerebral perfusion alterations, while protein S-100B values were unaffected by shunting strategy. Routine shunting during surgery for symptomatic carotid stenosis may have the potential to prevent postoperative increase of serum NSE levels, a potential marker of brain injury. 相似文献59.
Recent work has shown that the accuracy of ab initio structure prediction can be significantly improved by integrating evolutionary information in form of intra-protein residue-residue contacts. Following this seminal result, much effort is put into the improvement of contact predictions. However, there is also a substantial need to develop structure prediction protocols tailored to the type of restraints gained by contact predictions. Here, we present a structure prediction protocol that combines evolutionary information with the resolution-adapted structural recombination approach of Rosetta, called RASREC. Compared to the classic Rosetta ab initio protocol, RASREC achieves improved sampling, better convergence and higher robustness against incorrect distance restraints, making it the ideal sampling strategy for the stated problem. To demonstrate the accuracy of our protocol, we tested the approach on a diverse set of 28 globular proteins. Our method is able to converge for 26 out of the 28 targets and improves the average TM-score of the entire benchmark set from 0.55 to 0.72 when compared to the top ranked models obtained by the EVFold web server using identical contact predictions. Using a smaller benchmark, we furthermore show that the prediction accuracy of our method is only slightly reduced when the contact prediction accuracy is comparatively low. This observation is of special interest for protein sequences that only have a limited number of homologs. 相似文献
60.
We derive statistical properties of standard methods for monitoring of habitat cover worldwide, and criticize them in the context of mandated seagrass monitoring programs, as exemplified by Posidonia oceanica in the Mediterranean Sea. We report the novel result that cartographic methods with non-trivial classification errors are generally incapable of reliably detecting habitat cover losses less than about 30 to 50%, and the field labor required to increase their precision can be orders of magnitude higher than that required to estimate habitat loss directly in a field campaign. We derive a universal utility threshold of classification error in habitat maps that represents the minimum habitat map accuracy above which direct methods are superior. Widespread government reliance on blind-sentinel methods for monitoring seafloor can obscure the gradual and currently ongoing losses of benthic resources until the time has long passed for meaningful management intervention. We find two classes of methods with very high statistical power for detecting small habitat cover losses: 1) fixed-plot direct methods, which are over 100 times as efficient as direct random-plot methods in a variable habitat mosaic; and 2) remote methods with very low classification error such as geospatial underwater videography, which is an emerging, low-cost, non-destructive method for documenting small changes at millimeter visual resolution. General adoption of these methods and their further development will require a fundamental cultural change in conservation and management bodies towards the recognition and promotion of requirements of minimal statistical power and precision in the development of international goals for monitoring these valuable resources and the ecological services they provide. 相似文献