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排序方式: 共有7840条查询结果,搜索用时 31 毫秒
81.
The binding of [3H]paroxetine to serotonin uptake sites in human platelets from 47 individuals between 15 and 95 years of age was investigated. There were no significant age-related changes in maximal binding capacity (Bmax) or apparent binding affinity (Kd). There were no significant differences in binding between males (n = 19) and females (n = 28). 相似文献
82.
Leslie C. Grammer Loui Silvestri Irena M. Suszko Martha A. Shaughnessy Roy Patterson 《The Journal of allergy and clinical immunology》1983,72(2):160-167
The standardization procedures for polymerized ragweed (PRW) must evaluate activity of PRW with assessments that differ from those used for standard unmodified extracts. This is because PRW allergens are different from conventional ragweed extracts in that they are much greater in average molecular weight and much lower in allergenicity for equivalent immunogenicity. We have evaluated seven samples of PRW for three parameters: allergenicity as determined by cutaneous end point titration, molecular weight distribution as determined by Sephadex G-200 chromatography, and availability of antigen E (AgE) determinants as measured by the ability of an extract to inhibit AgE binding to antibody by using a modification of the Farr technique. The skin test titers and molecular weight profiles provide information as to the safety of a PRW preparation and antigen-binding inhibitory activity gives information about allergenicity and immunogenicity. Appropriate limits may be set for each of these parameters to standardize PRW for clinical use. 相似文献
83.
Lynch G Kohler S Leser J Beil M Garcia-Marin LJ Lutz MP 《Pflügers Archiv : European journal of physiology》2004,448(4):445-451
The aim of this study was to establish whether the rate of fatty acid (FA) incorporation and its utilization by the isolated soleus muscle is modified under conditions of thyroid hormone deficit or excess. The rate of palmitic acid (PA) uptake, oxidation and incorporation into intramuscular lipids with increasing PA concentration (0.5–1.5 mM) in the incubation medium were determined. In hypothyroid rats intramuscular triacylglycerol (TG) synthesis was increased, while the rate of PA oxidation to CO2 and incorporation into mono- and diacylglycerols (MG/DG) and phospholipids (PL) remained unchanged. In rats with triiodothyronine (T3) excess the rate of all processes studied was enhanced, although the percentage incorporation of PA into different classes of intramuscular lipids was fairly constant and, independently of thyroid state and FA concentration in the medium, was 56–66% for TG, 9-14% for MG/DG and 24–32% for PL. Our results thus indicate that even short-term T3 excess accelerates the rate of FA uptake and metabolism in the oxidative soleus muscle, whereas in hypothyroid rats only intramuscular TG synthesis is affected. 相似文献
84.
Mourot L Hintzy F Messonier L Zameziati K Belli A 《European journal of applied physiology》2004,93(3):325-332
This study proposed a non-invasive method to determine the gross (GE, no baseline correction), net (NE, resting metabolism as the baseline correction) and work (WE, unloaded cycling as the baseline correction) efficiencies during cycling at an intensity higher than the maximal aerobic power (MAP). Twelve male subjects performed two exercises consisting of 4 min at 50% MAP followed either by 8 min at 63% MAP or by 8 sequences of 60 s divided into 10 s at 130% MAP and 50 s at 50% MAP (i.e., 63% MAP on average). Oxygen uptake was continuously measured to calculate GE, NE and WE at 50%, 63% and 130% MAP, and the data presented as the means and standard deviations. The GE values were 18.2%, 19.1%, 22.7%, the NE values were 22.4%, 22.8%, 24.3% and the WE values were 34.2%, 31.4% and 27.2% at 50%, 63% and 130% MAP, respectively. The GE and NE increased (P<0.001) whereas the WE decreased (P<0.001) with each increment in power output. The GE was lower than the NE (P<0.001) at 50% and 63% MAP and than the WE (P<0.001) at all intensities. The NE was lower (P<0.001) than the WE at 50% and 63% MAP. These results showed that (1) efficiency index values obtained during supra-maximal exercise were consistent with previous proposals and (2) the efficiency-power output relationships were not limited to sub-maximal intensity levels but were confirmed at higher power output. 相似文献
85.
The concept of the accumulated O2 deficit (AOD) assumes that the O2 deficit increases monotonically with increasing work rate (WR), to plateau at the maximum AOD, and is based on linear extrapolation of the relationship between measured steady-state oxygen uptake (O2) and WR for moderate exercise. However, for high WRs, the measured O2 increases above that expected from such linear extrapolation, reflecting the superimposition of a "slow component" on the fundamental O2 mono-exponential kinetics. We were therefore interested in determining the effect of the O2 slow component on the computed AOD. Ten subjects [31 (12) years] performed square-wave cycle ergometry of moderate (40%, 60%, 80% and 90%
), heavy (40%), very heavy (80%) and severe (110% O2 peak) intensities for 10–15 min, where
is the estimated lactate threshold and is the WR difference between
and O2 peak. O2 was determined breath-by-breath. Projected "steady-state" O2 values were determined from sub-
tests. The measured O2 exceeded the projected value after ~3 min for both heavy and very heavy intensity exercise. This led to the AOD actually becoming negative. Thus, for heavy exercise, while the AOD was positive [0.63 (0.41) l] at 5 min, it was negative by 10 min [–0.61 (1.05) l], and more so by 15 min [–1.70 (1.64) l]. For the very heavy WRs, the AOD was [0.42 (0.67) l] by 5 min and reached –2.68 (2.09) l at exhaustion. For severe exercise, however, the AOD at exhaustion was positive in each case: +1.69 (0.39) l. We therefore conclude that the assumptions underlying the computation of the AOD are invalid for heavy and very heavy cycle ergometry (at least). Physiological inferences, such as the "anaerobic work capacity", are therefore prone to misinterpretation. 相似文献
86.
A. Dörge F. X. Beck G. Rechkemmer 《Pflügers Archiv : European journal of physiology》1998,436(2):280-288
The mammalian distal colon, which is composed of different cell types, actively transports Na, K and Cl in absorptive and
K and Cl in secretory directions. To further characterize the K absorption process and to identify the cells involved in K
absorption, unidirectional Rb fluxes and luminal Rb uptake into different epithelial cell types were determined in isolated
guinea-pig distal colon. Net Rb absorption (1.5–2.5 μmol·h–1·cm–2) was not influenced by inhibition of Na transport with amiloride or by incubating both sides of the epithelium with Na-free
solutions, but was almost completely abolished by luminal ouabain, ethoxzolamide or by incubating both sides of the epithelium
with Cl-free solutions. Luminal Rb uptake, blockable by luminal ouabain, preferentially occurred in columnar surface and neck
cells, to a lesser extent in surface goblet cells and to an insignificant degree in lower crypt cells. Employing a luminal
Rb-Ringer (5.4 mM Rb) the Rb concentration increased within 10 min in columnar surface and neck, surface goblet and lower
crypt cells to 70, 32 and about 10 mmol·kg–1 wet weight, respectively. The presence of 5.4 mM K in the luminal incubation solution reduced Rb uptake almost completely
indicating a much higher acceptance of the luminal H-K-ATPase for K than for Rb. The increase in Na and decrease in K concentrations
in surface and neck cells induced by luminal ouabain might indicate inhibition of the basolateral Na-K-ATPase or drastic enhancement
of cellular Na uptake by the Na-H exchanger. Bilateral Na-free incubation did not alter Rb uptake, but bilateral Cl-free incubation
drastically reduced it. Inhibition of net Rb absorption by ethoxzolamide and inhibition of both Rb absorption and Rb uptake
by bilateral Cl-free incubation support the notion that cellular CO2 hydration is a necessary prerequisite for K absorption and that HCO3 leaves the cell via a Cl-HCO3 exchanger. Since ouabain-inhibitable transepithelial Rb flux and luminal Rb uptake rate by surface and neck cells were about
the same, Rb(K) absorption seems to be accomplished mainly by columnar surface cells.
Received: 4 August 1997 / Received after revision: 12 November 1997 / Accepted: 4 December 1997 相似文献
87.
88.
M. B. Bromberg G. Pamel B. S. Stephenson A. B. Young J. B. Penney 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1987,69(1):53-59
Summary High affinity glutamate uptake into corticofugal fiber terminals was measured in the ventrolateral thalamus and red nucleus at varying time intervals after lesions were made by kainic acid in the contralateral interpositus nucleus of the cerebellum in rats. Under similar conditions the density of cortical fiber terminals was estimated using the Fink-Heimer impregnation technique. 1. Glutamate uptake steadily increased in the ventrolateral thalamus up to 60 days after lesions in the contralateral cerebellum. 2. Similar changes were noted in the red nucleus. 3. The changes were dependent on the integrity of corticofugal fibers to the thalamus and red nucleus. 4. No changes in uptake of gammaaminobutyric acid were noted. 5. Saturation curves for glutamate uptake suggested a change in the maximal number of transport sites. 6. Fink-Heimer degeneration studies showed an increase in cortical terminals in the ipsilateral ventrolateral thalamus and in both rostral and caudal regions of the red nucleus following lesions in the contralateral interpositus nucleus. The data are consistent with an increase in the number of cortical fiber terminals in reaction to loss of cerebellar input to the ventrolateral thalamus and red nucleus. This study correlates anatomical and biochemical evidence for collateral sprouting in a model based on electrophysiologic data in the red nucleus and extends the model to include the thalamus. 相似文献
89.
Puente-Maestu L Sánz ML Sánz P Nuñez A González F Whipp BJ 《European journal of applied physiology》2001,85(5):434-441
To be clinically useful as indices reflective of altered physiological function consequent to interventions in patients with
chronic obstructive pulmonary disease (COPD), the time constant (τ) and steady-state amplitude of the kinetic responses for
oxygen uptake (
) carbon dioxide output (
) ventilation (
) and heart rate (HR) have to be appropriately differentiable and reproducible. We therefore assessed the reproducibility
of τ and steady state amplitude values in 41 patients with severe COPD [mean (SD)] [forced expiratory volume in 1 s=41 (7)%
predicted], aged 64 (5) years. Of the total, 6 of the patients (15%) did not produce breath-by-breath data of sufficient quality
to warrant kinetic analysis. The remaining 35 patients completed two moderate-intensity 10 min square-wave exercise tests
separated by 2 h, both before and after an endurance training programme. Tests were conducted on an electromagnetically-braked
cycle ergometer at an exercise intensity corresponding to 80% of the estimated lactate threshold (θLa) or 50% of peak oxygen uptake if θLa was insufficiently differentiable. Breath-by-breath measurements of
,
,
and HR were averaged into 10 s bins and the on-transient response kinetics were estimated using a mono-exponential model.
Analysing the pre-training and the post-training test 1 and test 2 comparisons together, the test 1 –test 2 differences were
not significantly different from 0 for either τ or A. The standard deviation of the test 1 –test 2 differences allowed us
to define the magnitude of change that would reach statistical significance. For τ, this averaged some 8, 10, 11 and 8 s,
for
,
,
and HR, respectively, for a one-tailed paired-comparisons test (i.e. appropriate for assessing hypothesised improvements resulting
from an intervention); for a two-tailed comparison, the differences were approximately 2 s greater. The corresponding one-tailed
values for A were 100 ml·min–1, 95 ml·min–1, 2.5 1·min–1 and 4 beats·min–1, respectively; the two-tailed values were 10%–15% greater. We therefore conclude that both τ and A for moderate-intensity
exercise can be reproducibly estimated in patients with COPD when the data set provides a sufficiently large amplitude of
response and sufficiently low sample variability to allow appropriate parameter estimation.
Electronic Publication 相似文献
90.
C. Strazielle R. Lalonde L. Riopel M.I. Botez T.A. Reader 《Journal of chemical neuroanatomy》1996,10(2):157-171
The neurological cerebellar mutant lurcher is characterized by a primary degeneration of Purkinje cells as well as a retrograde secondary partial degeneration of cerebellar granule cells and inferior olivary neurons. Since serotonin (5-HT) has been implicated in the modulation of excitatory amino acid systems of the cerebellum, the 5-HT innervation of the normal and lurcher mice was examined by quantifying uptake sites using [3H]citalopram autoradiography, and by biochemical assays of the indoles 5-HT, 5-hydroxy-
-tryptophan and 5-hydroxyindole-3-acetic acid using high-performance liquid chromatography. Comparable results were found between [3H]citalopram binding and 5-HT tissue concentrations in different brain regions. The highest [3H]citalopram labelling was observed in defined structures of the mesencephalic and upper pontine regions, in limbic structures, in hypothalamus and in discrete thalamic divisions, while the lowest labelling of uptake sites was documented in cerebellum and brainstem reticular formation. In lurcher mutants, the histology confirmed cell degeneration and the reduction in width, leading to 65%, 45% and 25% atrophies of total cerebellum, deep nuclei and inferior olivary nucleus, respectively. The [3H]citalopram labelling corrected for surface loss was 45% and 20% higher in cerebellar deep nuclei and red nucleus, respectively, but remained unchanged in the cerebellar cortex and inferior olivary nucleus. Moreover, higher labelling was found in nucleus raphe dorsalis, ventral tegmental area, inferior colliculus, locus coeruleus, pontine central grey and anterior thalamic nuclei, areas known to be part of cerebellar afferent and efferent systems. The present results indicate that in such pathological conditions as described for the lurcher mutant, the 5-HT system may modulate motor function not only at the level of the cerebellum, but also in other forebrain structures functionally related to the motor system. 相似文献