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101.
García-Machorro Jazmin Mirzaeicheshmeh Elaheh Fragoso-Vázquez Manuel Jonathan Bello Martiniano Méndez-Luna David León-Cardona Alám Correa-Basurto José 《化学与生物多样性》2023,20(7):e202201077
Antiviral resistance has turned into a world concern nowadays. Influenza A H1N1 emerged as a problem at the world level due to the neuraminidase (NA) mutations. The NA mutants conferred resistance to oseltamivir and zanamivir. Several efforts were conducted to develop better anti-influenza A H1N1 drugs. Our research group combined in silico methods to create a compound derived from oseltamivir to be tested in vitro against influenza A H1N1. Here we show the results of a new compound derived from oseltamivir but with specific chemical modifications, with significant affinity either on NA (in silico and in vitro assays) or HA (in silico) from influenza A H1N1 strain. We include docking and molecular dynamics (MD) simulations of the oseltamivir derivative at the binding site onto NA and HA of influenza A H1N1. Additionally, the biological experimental results show that oseltamivir derivative decreases the lytic-plaque formation on viral susceptibility assays, and it does not show cytotoxicity. Finally, oseltamivir derivative assayed on viral NA showed a concentration-dependent inhibition behavior at nM, depicting a high affinity of the compound for the enzyme, corroborated with the MD simulations results, placing our designed oseltamivir derivative as a potential antiviral against influenza A H1N1. 相似文献
102.
Aiko Kiso Koushi Hidaka Tooru Kimura Yoshio Hayashi Azin Nezami Ernesto Freire Yoshiaki Kiso 《Journal of peptide science》2004,10(11):641-647
Plasmepsin (Plm) has been identified as an important target for the development of new antimalarial drugs, since its inhibition leads to the starvation of Plasmodium falciparum. A series of substrate-based dipeptide-type Plm II inhibitors containing the hydroxymethylcarbonyl isostere as a transition-state mimic were synthesized. The general design principle was provision of a conformationally restrained hydroxyl group (corresponding to the set residue at the P2' position in native substrates) and a bulky unit to fit the S2' pocket. 相似文献
103.
104.
The accessibility of embryonic and adult neurons within invertebrate nervous systems has made them excellent subjects for
neurobiological study. The ability to readily identify individual neurons, together with their great capacity for regeneration,
has been especially beneficial to investigations of synapse formation and the specificity of neuronal connectivity. Many invertebrate
neurons survive for long periods following isolation into primary cell culture. In addition, they readily extend new neuritic
arbors and form electrical and chemical connections at sites of contact. Thus, cell culture approaches have allowed neuroscientists
greater access to, and resolution of, events underlying neurite outgrowth and synaptogenesis. Studies of identified neuromuscular
synapses ofHelisoma have determined a number of signaling mechanisms involved in transsynaptic communication at sites of neuron-target contact.
At these sites, both anterograde and retrograde signals regulate the transformation of growth cones into functional presynaptic
terminals. We have found that specific muscle targets induce both global and local changes in neurotransmitter secretion and
intracellular calcium handling. Here we review recent studies of culturedHelisoma synapses and discuss the mechanisms thought to govern chemical synapse formation in these identified neurons and those of
other invertebrate species. 相似文献
105.
A simple approach to determine CO2/O2 specificity factor () of ribulose 1,5-bisphosphate carboxylase/oxygenase is described. The assay measures the amount of CO2 fixation at varying [CO2]/[O2] ratios after complete consumption of ribulose 1,5-bisphosphate (RuBP). Carbon dioxide fixation catalyzed by the carboxylase was monitored by directly measuring the moles of 14CO2 incorporated into 3-phosphoglycerate (PGA). This measurement at different [CO2]/[O2] ratios is used to determine graphically by several different linear plots the total RuBP consumed by the two activities and the CO2/O2 specificity factor. The assay can be used to measure the amounts of products of the carboxylase and oxygenase reactions and to determine the concentration of the substrate RuBP converted to an endpoint amount of PGA and phosphoglycolate. The assay was found to be suitable for all [CO2]/[O2] ratios examined, ranging from 14 to 215 micromolar CO2 (provided as 1–16 mM NaHCO3) and 614 micromolar O2 provided as 50% O2. The procedure described is extremely rapid and sensitive. Specificity factors for enzymes of highly divergent values are in good agreement with previously published data.Abbreviations HEPPS
N-(2-hydroxyethyl)piperazine-N-(3-propanesulfonic acid)
- L
large subunit of rubisco
- PGA
3-phosphoglyceric acid
- rubisco
ribulose 1,5-bisphosphate carboxylase/oxygenase
- RuBP
d-ribulose 1,5-bisphosphate
- S
small subunit of rubisco
- XuBP
d-xylulose 1,5-bisphosphate 相似文献
106.
Summary In the laboratory, the two species of copepodsLepeophtheirus thompsoni andLepeophtheirus europaensis, ectoparasites of flatfishes, can meet and mate on at least one host species. In the wild however, these two species are found isolated on their sympatric hosts. Habitat selection theoretically represents a powerful enough mechanism to explain the maintenance of genetic heterogeneity in the wide sense. In this paper, the host colonization process is studied for both parasite species. It is shown that each parasite can develop and reach adult age on each host species. However,L. thompsoni is highly selective; it almost totally refuses to colonize hosts other than its natural one.Lepeophtheirus europaensis, on the contrary, readily infests turbot and brill in single-host experiments, but strongly prefers the brill when it has a choice. It appears that these two genetic entities are sympatrically maintained due to strong habitat selection. Such a pattern could theoretically only occur in a soft-selection context (density dependence). This point is discussed with respect to the different patterns in host use found in the geographical distribution of these parasites. 相似文献
107.
Brown trout ( Salmo trutta ) from anadromous River Lierelva, resident Lake Tunhovd, and resident Nordmarka stocks were exposed to Gyrodactylus salaris -infected salmon parr. The brown trout were fed pellets before the experiments, except for one group of the Nordmarka stock which was starved for 19 days before the experiments. The mean number of parasites declined directly and rapidly post infection for all groups of trout. There were no pronounced differences in resistance between the anadromous and the resident stocks. G. salaris infections tended to persist longer on starved than on fed trout of the Nordmarka stock. The maximum parasite persistence on trout was 50 days, and as parasite numbers increased on some fish parasite reproduction must have occurred on those trout. However, the limited susceptibility and marked innate resistance of trout to G. salaris establishment, development and reproduction, suggest parasite metapopulations will not survive on this species. Nevertheless, trout may still play a role in the dispersal of G. salaris within and between rivers. 相似文献
108.
Laura Chiarantini Luigia Rossi Alessandra Fraternale Mauro Magnani 《Molecular and cellular biochemistry》1995,144(1):53-59
Human and murine blood cells treated with ZnCl2 and bis(sulfosuccinimidyl)suberate (BS3) (a cross linking agent) undergo band 3 clustering and binding of hemoglobin to red blood cell membrane proteins. These clusters induce autologous IgG binding and complement fixation, thus favouring the phagocytosis of ZnCl2/BS3 treated cells by macrophages. The extension of red blood cell opsonization can be easily modulated by changing the ZnCl2 concentration in the 0.1–1.0 mM range thus providing an effective way to affect blood cell recognition by macrophages. In fact, murine erythrocytes treated with increasing ZnCl2 concentrations have proportionally reduced survivals when reinjected into the animal. Furthermore, the organ sequestration of ZnCl2/BS3 treated cells strongly resembles the typical distribution of the senescent cells. Since the ZnCl2/BS3 treatment can also be performed on red blood cells loaded with drugs or other substances, this procedure is an effective drug-targeting system to be used for the delivery of molecules to peritoneal, liver and spleen macrophages. 相似文献
109.
Paul G. Braunschweiger Vathsala S. Basrur Dayna Cameron Laura Sharpe Octavio Santos James P. Perras Bernd-Uwe Sevin Arnold M. Markoe 《Biotherapy》1997,10(2):129-137
The modulation of cisPlatin cytotoxicity by interleukin-1 (IL-1α) was studied in cultures of SCC-7 tumor cells with and without
tumor macrophages to examine potential mechanisms for the synergistic antitumor activity of cisPlatin and IL-1α in SCC-7 solid
tumors. Neither IL-1α nor tumor macrophages affected the survival of clonogenic tumor cells and IL-1α had no direct effect
on tumor cell growthin vitro. Macrophages had no direct effect on cisPlatin sensitivity (IC90=6.0 μM), but, the addition of IL-1α (500–2000U/ml) to co-cultures of cisPlatin pretreated tumor cells and resident tumor
macrophages increased cell killing (IC90=3.1 μM). Similar responses were seen in primary cultures treated with cisPlatin before IL-1α. The modulation of cisPlatin
cytotoxicity by IL-1α exhibited a biphasic dose response that paralleled the IL-1α dose dependent release of H2O2by resident tumor macrophages. Further, IL-1α modification of cisPlatin cytotoxicity was prompt and inhibited by catalase.
CisPlatin and exogenous H2O2 (50 μM) produced more than additive SCC-7 clonogenic cell kill and hydroxyl radicals played an important role in the response.
Interleukin-1 modulation of cisPlatin cytotoxicity was schedule dependent. IL-1α treatment for 24 hrs, before cisPlatin, produced
drug resistance (IC90=11.1 μM). Our study shows that IL-1α can stimulate tumor macrophages to release pro-oxidants that modify cellular chemosensitivity
in a schedule and dose dependent fashion. Our findings may also provide a mechanistic explanation for the synergistic antitumor
activity of cisPlatin and IL-1αin vivo. 相似文献
110.
A. L. P. Freitas D. I. A. Teixeira F. H. F. Costa W. R. L. Farias A. S. C. Lobato A. H. Sampaio N. M. B. Benevides 《Journal of applied phycology》1997,9(6):495-501
Aqueous protein extracts from 30 Brazilian marine algae were examined for haemagglutinating activity using native and enzyme-treated
rabbit, chicken, sheep and human erythrocytes. Most extracts agglutinated at least one of the blood cells used. Sheep and
rabbit erythrocytes were more suitable for detection of the agglutinating activity. The minimum protein concentration necessary
to produce positive agglutination was usually lower with enzyme-treated erythrocytes than native ones. The five algal protein
extracts showing the greatest haemagglutination titre were tested for sugar-binding specificity. Only the activity present
in the green alga Cauler pacupressoides was inhibited by simple sugars and not by the glycoproteins tested. The activity of
the other four extracts was inhibited by at least one of the glycoproteins utilised.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献