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Homozygous typing cells (HTC) were primed, using responding and stimulating lymphocytes of the same HLA-D groups. These intra-HLA-D group primings showed strong specific responses. Restimulation by HLA-D heterozygous and homozygous cell panels showed no correlation between the restimulating determinant and HLA-D. On the other hand, an unrelated individual, not carrying Dw4 and primed to Dw4 HTC, is restimulated by three of four Dw4-HTC. Thus, one non-HLA-D-associated restimulating determinant and another HLA-D-associated determinant could be identified. The differences among the four Dw4 HTC recognized in secondary MLC could reflect either recognition of separate gene products or recognition of separate determinants on the same gene product. 相似文献
4.
Victor M. Luque-Almagro Verity J. Lyall Stuart J. Ferguson M. Dolores Roldán David J. Richardson Andrew J. Gates 《The Journal of biological chemistry》2013,288(41):29692-29702
Nitrogen is an essential nutrient for growth and is readily available to microbes in many environments in the form of ammonium and nitrate. Both ions are of environmental significance due to sustained use of inorganic fertilizers on agricultural soils. Diverse species of bacteria that have an assimilatory nitrate/nitrite reductase system (NAS) can use nitrate or nitrite as the sole nitrogen source for growth when ammonium is limited. In Paracoccus denitrificans, the pathway-specific two-component regulator for NAS expression is encoded by the nasT and nasS genes. Here, we show that the putative RNA-binding protein NasT is a positive regulator essential for expression of the nas gene cluster (i.e. nasABGHC). By contrast, a nitrogen oxyanion-binding sensor (NasS) is required for nitrate/nitrite-responsive control of nas gene expression. The NasS and NasT proteins co-purify as a stable heterotetrameric regulatory complex, NasS-NasT. This protein-protein interaction is sensitive to nitrate and nitrite, which cause dissociation of the NasS-NasT complex into monomeric NasS and an oligomeric form of NasT. NasT has been shown to bind the leader RNA for nasA. Thus, upon liberation from the complex, the positive regulator NasT is free to up-regulate nas gene expression. 相似文献
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Francesc Gòdia Carles Casas Bernardo Castellano Carles Solà 《Applied microbiology and biotechnology》1987,26(4):342-346
Summary Data of cell concentration, viability and microscopic observation of cell distribution inside carrageenan immobilized yeast beads are reported. Results were obtained from a continuous packed-bed reactor performing alcoholic fermentation and the main observations made on cell activity are in agreement with the fermentation profiles inside the fermenter. 相似文献
6.
J. Čatský D. K. Velichkov Jana Pospísilová Jarmila Solárová Ingrid Tichá 《Biologia Plantarum》1987,29(5):355-364
The carbon balances of whole, 21-d old French bean plants (Phaseolus vulgaris L.) grown in standard nutrient solution (1K) and its modifications without (OK) or surplus (2K) potassium were calculated
from the daily photosynthetic carbon inputs of individual leaves, and the daily respiratory carbon losses by individual leaves,
stalks and petioles, and roots. Under the three K concentrations, maximum net photosynthetic rates (Pn) were found in the 2nd or in the 3rd trifoliate leaves, maximum respiratory rates (Rd) in the youngest, 4th trifoliate leaves; the Pn/Rd ratio decreased with leaf age. In all leaves of 2K plants, leaf dry masses and thicknesses, Pn, Pn/Pd ratios, and stomatal and intracellular conductances were lower than in OK and IK plants. Daily whole-plant net carbon gain
was highest in IK plants, whereas in OK and 2K plants it was 98.0 and 81.3 % of IK, respectively. Similar values were found
in the parameters of growth analysis, namely in net assimilation rates and relative growth rates.
No differences were found in water potential (Ψ
w
) or water saturation deficit (Wsat) in the OK, 1K and 2K plants sufficiently supplied with water or during wilting and resaturation. The decrease in Ψw to −0.97 MPa was associated with a 19.9 %, 31.4 % and 23.4 % decrease in Pn of OK, 1K and 2K plants, respectively, but no effect on Rd was found. In the three variants, the short-time effect of mild water stress was fully reversible. 相似文献
7.
Caminal G Lafuente J López-Santín J Poch M Solà C 《Biotechnology and bioengineering》1987,29(3):366-369
A recursive estimation scheme, the Extended Kalman Filter (EKF) technique, was applied to study enzymatic deactivation in the enzymatic hydrolysis of pretreated cellulose using a model previously developed by the authors. When no deactivation model was assumed, the results showed no variation with time for all the model parameters except for the maximum rate of cellobiose-to-glucose conversion (r'(m)).The r'(m) variation occurred in two zones with a grace period. A new model of enzymatic hydrolysis of pretreated cellulose deactivation was proposed and validated showing better behavior than the old deactivation model. This approach allows one to study enzyme deactivation without additional experiments and within operational conditions. 相似文献
8.
Mathematical modelization of a packed-bed reactor performance with immobilized yeast for ethanol fermentation 总被引:1,自引:0,他引:1
The performance of a continuous vertical packed-bed reactor with yeast immobilized in carrageenan gel beads is reported. The study focuses on the mathematical modelling of the steady-state fermentor behavior by means of a tanks-in-series model which includes the intrinsic kinetic model and the external mass transfer and internal diffusion-reaction conditions in the beads. 相似文献
9.
The adenosine transport in cultured chromaffin cells was increased by the presence of triiodo-l-thyronine (T3) throughout the prolonged period studied. The Vmax values of this transport obtained in absence and presence of 1 M T3 were 36.21±2.1 and 44.17±3.5 (means±SD) pmol/106cells/min respectively for 26 hours incubation-time with the hormone. The Km values were not significantly modified. The number of adenosine transporters in cultured chromaffin cells, measured by [3H]nitrobenzylthioinosine (NBTI) binding, was increased by 1 M T3 for 26 hours incubation-time. The values of binding sites per cell were 33,500±3,000 and 40,153±3,700 in absence and presence of T3 respectively, without changing the Kd constant. When the transport studies were carried out in presence of cycloheximide, an inhibitor of protein synthesis, the adenosine transport capacity decreased with a half-life values of 23.9±2.8 and 24.3±2.1 hours both in the presence or absence of T3 respectively. When cells were incubated in the presence of both T3 and cycloheximide, not only the activatory effect of T3 was completely abolished but also adenosine transport was decreased to the same extent as with cycloheximide alone. These results indicated that T3 activation of adenosine transport in chromaffin cells required the protein-synthesizing mechanism. 相似文献
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