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91.
M. T. Kidd M. A. Qureshi P. R. Ferket L. N. Thomas 《Biological trace element research》1994,42(3):217-229
The ability of dietary zinc-methionine (Zn-Met) to enhance mononuclear-phagocytic function againstSalmonella arizona andenteritids was investigated in young turkeys. Feed/gain and body wt gain at 21 d of age were not affected by Zn-Met. The addition of
30 or 45 ppm Zn from Zn-Met to a Zn adequate diet significantly increased cutaneous basophil hypersensitivity to phytohemagglutinin-P.
The clearance of intravenously administeredS. enteritidis from blood was not affected by 30 ppm of supplemental Zn from Zn-Met. However, 30 ppm Zn from Zn-Met increased the reduction
of intravenously administeredS. arizona from spleen. Percentages of myeloid and mononuclear-phagocytic cells before and afterS. enteritidis infection were not affected by supplemental Zn-Met. Turkeys supplemented with Zn-Met showed enhanced in vitro phagocytosis
ofS. enteritidis by Sephadex-elicited abdominal exudate cells. The phagocytosis ofS. arizona was unaffected by Zn-Met. 相似文献
92.
Neutron-induced γ-ray emission tomography for quantitative determination of the concentration and distribution of elements
in a selected plane through a biological specimen is briefly explained and applied by way of illustration to the analysis
of gallstones. A system capable of carrying out studies of the binding site of75Se in different matrices using time differential perturbed angular correlation spectroscopy is also briefly described. Developments
in the detector technology of positron emission tomography have allowed small-diameter imaging devices to be built for in
vivo preclinical evaluation of new tracers in small animals and are discussed in the context of a proposed experiment combining
the techniques mentioned above. 相似文献
93.
Marco Vinceti Sergio Rovesti Cristina Marchesi Margherita Bergomi Gianfranco Vivoli 《Biological trace element research》1994,40(3):267-275
In a part of the municipal territory of Reggio Emilia, northern Italy, selenium in drinking water decreased from 7 μg/L to
less than 1 μg/L. In a cohort of 4419 individuals, previously exposed for at least 5 yr to the drinking water with higher
selenium content, the 7-yr temporal distribution of deaths for coronary disease and for stroke was analyzed to examine a possible
relationship with changes in drinking water selenium. From January 1986 until August 1988, when tap water selenium was 7 μg/L,
deaths for coronary disease were one in males and two in females. After the decrease in drinking water selenium, 21 and 10
coronary deaths were observed, respectively, in males and in females from September 1988 to December 1992. No significant
difference in the temporal distribution of stroke deaths was observed both in males and in females. Even if an effect of chance
and aging in the temporal distribution of coronary deaths may not be excluded, findings of the study seem to be consistent
with the hypothesis of a beneficial effect of selenium on coronary disease mortality. 相似文献
94.
An existing radiochemical NAA procedure for Cd, Co, and Cu was improved to allow determination of individual radiochemical
yields by the radioisotopic tracer technique, thus eliminating errors owing to variable recovery.109Cd was used as tracer for Cd determination via115Cd/115mIn,57Co for Co via60Co, and potentially for Ni via58Co, whereas as a novelty67Cu, produced by reactor irradiation of ZnO of natural isotopic composition (by the67Zn [n,p]67Cu reaction) was used for Cu via the indicator nuclide64Cu. The simple production and purification of67Cu by anion exchange is described. Results for biological RMs are given and discussed. 相似文献
95.
We hypothesized that manganese deficient animals fed high vs moderate levels of polyunsaturated fat would either manifest
evidence of increased oxidative stress or would experience compensatory changes in antioxidant enzymes and/or shifts in manganese
utilization that result in decreased endogenous gut manganese losses. Rats (females in Study 1, males in Study 2,n = 8/treatment) were fed diets that contained 5 or 20% corn oil by weight and either 0.01 or 1.5 μmol manganese/g diet. In
study 2,54Mn complexed to albumin was injected into the portal vein to assess gut endogenous losses of manganese. The manganese deficient
rats:
Gut endogenous losses of manganese tended to account for a smaller proportion of absorbed manganese in rats fed high-fat diets;
otherwise fat intake had few effects on tissue manganese concentrations. 相似文献
1. | Had 30–50% lower liver, tibia, kidney, spleen, and pancreas manganese concentrations than manganese adequate rats; |
2. | Conserved manganese through ≈70-fold reductions in endogenous fecal losses of manganese; |
3. | Had lower heart manganese superoxide dismutase (MnSOD) activity; and |
4. | Experienced only two minor compensatory changes in the activity of copper-zinc superoxide dismutase (CuZnSOD) and catalase. |
96.
Selenite has been shown to undergo intracellular metabolism that results in its conversion to other low molecular weight Secontaining
species and also to its incorporation into a selenocysteine residue in selenoprotein. In order to investigate whether the
incorporation into protein is required for the cytotoxic effects of selenite, we have examined whether inhibition of protein
synthesis prevents the inhibitory effect of selenite on the ability of cells to form colonies or to synthesize RNA. We have
found that treatment of HeLa cells with cycloheximide inhibited protein synthesis by >90% but had no effect on the inhibitory
effect of selenite on cell colony formation or RNA synthesis. Since protein synthesis is not necessary for these cytotoxic
effects of selenite they are unlikely to result from an increase in the synthesis of selenoproteins. 相似文献
97.
98.
Estimating regional carbon stocks and spatially covarying edaphic factors using soil maps at three scales 总被引:2,自引:1,他引:1
Most estimates of regional and global soil carbon stocks are based on extrapolations of mean soil C contents for broad categories
of soil or vegetation types. Uncertainties exist in both the estimates of mean soil C contents and the area over which each
mean should be extrapolated. Geographic information systems now permit spatially referenced estimates of soil C at finer scales
of resolution than were previously practical. We compared estimates of total soil C stocks of the state of Maine using three
methods: (1) multiplying the area of the state by published means of soil C for temperate forests and for Spodosols; (2) calculating
areas of inclusions of soil taxa in the 1:5,000,000 FAO/UNESCO Soils Map of the World and multiplying those areas by selected
mean carbon contents; and (3) calculating soil C for each soil series and map unit in the 1:250,000 State Soil Geographic
Data Base (STATSGO) and summing these estimates for the entire state. The STATSGO estimate of total soil C was between 23%
and 49% higher than the common coarse scale extrapolations, primarily because STATSGO included data on Histosols, which cover
less than 5% of the area of the state, but which constitute over one-third of the soil C. Spodosols cover about 65% of the
state, but contribute less than 39% of the soil C. Estimates of total soil C in Maine based on the FAO map agreed within 8%
of the STATSGO estimate for one possible matching of FAO soil taxa with data on soil C, but another plausible matching overestimated
soil C stocks. We also compared estimates from the 1:250,000 STATSGO database and from the 1:20,000 Soil Survey Geographic
Data Base (SSURGO) for a 7.5 minute quadrangle within the state. SSURGO indicated 13% less total soil C than did STATSGO,
largely because the attribute data on depths of soil horizons in SSURGO are more specific for this locality. Despite localized
differences, the STATSGO database offers promise of scaling up county soil survey data to regional scales because it includes
attribute data and estimates of areal coverage of C-rich inclusions within map units. The spatially referenced data also permit
examination of covariation of soil C stocks with soil properties thought to affect stabilization of soil C. Clay content was
a poor predictor of soil C in Maine, but drainage class covaried significantly with soil C across the state. 相似文献
99.
Slow cortical potential biofeedback and the startle reflex 总被引:4,自引:0,他引:4
Stuart Brody Harald Rau Fabiola Köhler Harald Schupp Werner Lutzenberger Niels Birbaumer 《Applied psychophysiology and biofeedback》1994,19(1):1-11
The negativity of slow cortical potentials (SCP) of the surface EEG is a measure of brain excitability, correlating with motor and cognitive preparation. Selfcontrol of SCP positivity has been shown to reduce seizure activity. Following SCP biofeedback from a central EEG electrode position, subjects gained bidirectional control over their SCP. The current study used a modified feedback methodology, and found a positive relationship between negativity and magnitude of EMG startle response (a measure of cortical and subcortical arousal, particularly aversive response disposition). Greater success in SCP differentiation was associated with self-report of less relaxation during negativity training.This research was supported by the Deutsche Forschungsgemeinschaft under grant No. SFB 307. 相似文献
100.
Jodi Willard Mary Johnson J. Peter Rosenfeld 《Applied psychophysiology and biofeedback》1994,19(1):13-24
Using a dual-task paradigm with an oddball secondary task, P300 amplitude and latency were studied as a function of factorially manipulated oddball probability (low = .22, high = .44) and primary task type. In addition to a Baselinecondition (oddball task only), three primary tasks were used: (1) Pure Sensory;watching a movie; (2) Pure Motor (manipulating a flashlight); and (3) Sensory/Motor(using the flashlight to trace the outlines of characters in a movie). The findings included the usual significant effects of probability on amplitude. There was also a significant effect of task type on amplitude, and a significant interaction of oddball probability with task type. In the low but not high probability condition, a pure Sensory task depressed P300 amplitude. In both probability conditions, the Sensory/motortask depressed P300 amplitude. Only task type had a significant effect on P300 latency. The results confirm the ability of other labs (using Sensory/motor primary tasks) to demonstrate P300 depression at high oddball probability, in view of the difficulty in our lab of achieving P300 depression with pure sensory tasks and high oddball probabilities. The results are discussed in terms of partial overlap of processing resource pools.
A preliminary report of these data was presented at the 1990 meetings of the Society for Psychophysiological Research. 相似文献