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51.
环境参数变化对γ射线诱变微生物的影响 总被引:1,自引:0,他引:1
报告了在非自然环境中培养选育青霉菌菌株的一些结论。实验表明随着辐射剂量的增加菌株的致死率也相应增加;当辐照剂量相同时,与自然环境相比其致死率有所提高,且随着非自然环境参数值的增加而增加。当电场强度为300kV/m、磁场强度为600Gs时,正变率有一极大值。 相似文献
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Dear Editor,
Sex determination is one of the most fundamental develop-ment processes,as gender is the first and most important identity of human.In most mammals... 相似文献
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Increased nutrient availability can have a large impact in Australian woodland ecosystems, many of which are very poor in
nutrients, particularly phosphorus. A study was conducted in an urban Banksia woodland remnant in Perth, southwest Western Australia to test the hypothesis that the soil nutrient status in areas in good
condition (GC), poor condition invaded by the perennial grass Ehrharta calycina (PCe), and poor condition invaded by the perennial herb Pelargonium capitatum (PCp), is reflected in the nutrient status of the native and introduced species. Leaf concentrations of P, K, N, Na, Ca,
Mg, S, B, Cu, Fe, Mn and Zn of six native (Banksia attenuata, Banksia menziesii, Allocasuarina humilis, Melaleuca systena, Macrozamia fraseri and Conostylis aculeata) and four introduced species (Ehrharta calycina, Pelargonium capitatum, Gladiolus caryophyllaceus and Briza maxima), were measured. Soil pH, electrical conductivity, N (total), P (total), available P, K, S and organic C were assessed beneath
all species on all sites. Significantly higher concentrations of soil P (total) and P (HCO3) were found at PCe and PCp sites than GC sites, while PCp sites also had significantly higher soil concentrations for N (total)
and S. Principal Components Analysis of the leaf analyses showed (a) individual species have characteristically different
nutrient concentrations; (b) the introduced species Ehrharta calycina and Pelargonium capitatum clustered separately from each other and by vegetation condition. Leaf concentrations of P were significantly (P<0.05) higher, and K and Cu were significantly lower in PCe and PCp sites compared with those at GC sites. Introduced species
leaf nutrient concentrations were significantly greater than native species for all nutrients except Mn which was significantly
lower, with no differences for Mg and B. The results indicate a key role for P in the Banksia woodland, and we conclude that higher levels of available P at invaded sites are having a detrimental impact on the ecosystem.
These results provide new knowledge to enhance conservation practices for the management of the key threatening process of
invasion within a biodiversity hot spot.
Section Editor: T. Kalapos 相似文献
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The objectives of this study were to investigate the moisture-induced protein aggregation of whey protein powders and to elucidate
the relationship of protein stability with respect to water content and glass transition. Three whey protein powder types
were studied: whey protein isolate (WPI), whey protein hydrolysates (WPH), and beta-lactoglobulin (BLG). The water sorption
isotherms were determined at 23 and 45°C, and they fit the Guggenheim–Andersson–DeBoer (GAB) model well. Glass transition
was determined by differential scanning calorimeter (DSC). The heat capacity changes of WPI and BLG during glass transition
were small (0.1 to 0.2 Jg−1 °C−1), and the glass transition temperature (T
g) could not be detected for all samples. An increase in water content in the range of 7 to 16% caused a decrease in T
g from 119 down to 75°C for WPI, and a decrease from 93 to 47°C for WPH. Protein aggregation after 2 weeks’ storage was measured
by the increase in insoluble aggregates and change in soluble protein fractions. For WPI and BLG, no protein aggregation was
observed over the range of 0 to 85% RH, whereas for WPH, ∼50% of proteins became insoluble after storage at 23°C and 85% RH
or at 45°C and ≥73% RH, caused mainly by the formation of intermolecular disulfide bonds. This suggests that, at increased
water content, a decrease in the T
g of whey protein powders results in a dramatic increase in the mobility of protein molecules, leading to protein aggregation
in short-term storage. 相似文献
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Zheng P Gao HC Li Q Shao WH Zhang ML Cheng K Yang de Y Fan SH Chen L Fang L Xie P 《Journal of proteome research》2012,11(3):1741-1748
Major depressive disorder (MDD) is a socially detrimental psychiatric disorder, contributing to increased healthcare expenditures and suicide rates. However, no empirical laboratory-based tests are available to support the diagnosis of MDD. In this study, a NMR-based plasma metabonomic method for the diagnosis of MDD was tested. Proton nuclear magnetic resonance ((1)H NMR) spectra of plasma sampled from first-episode drug-na??ve depressed patients (n = 58) and healthy controls (n = 42) were recorded and analyzed by orthogonal partial least-squares discriminant analysis (OPLS-DA). The OPLS-DA score plots of the spectra demonstrated that the depressed patient group was significantly distinguishable from the healthy control group. Moreover, the method accurately diagnosed blinded samples (n = 26) in an independent replication cohort with a sensitivity and specificity of 92.8% and 83.3%, respectively. Taken together, NMR-based plasma metabonomics may offer an accurate empirical laboratory-based method applicable to the diagnosis of MDD. 相似文献
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