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排序方式: 共有987条查询结果,搜索用时 15 毫秒
101.
OBJECTIVE: An exaggerated blood pressure response to mental stress in postmenopausal women has been reported but the underlying mechanism is not clear. In the present study, we examined the role of estrogen in the blood pressure response to mental stress. SUBJECTS AND METHODS: Hemodynamic responses to mental stress and constrictor responses to norepinephrine were compared in 18 premenopausal (mean +/- SD age 33 +/- 5 years), 22 postmenopausal women (62 +/- 7 years) and 13 postmenopausal women with estrogen replacement therapy (58 +/- 8 years). Premarin was infused in 10 postmenopausal women to determine whether estrogen attenuates norepinephrine-induced vasoconstriction. The hemodynamic responses to a standard mental arithmetic test were measured. Norepinephrine (12.5, 25, 50, 100 ng/min) was infused at 0.5 ml/min for 5 min via the dorsal hand vein. Norepinephrine (100 ng/min) combined with premarin (200 microg/min) was infused into the dorsal hand vein of postmenopausal women. Changes in venous diameter were measured by ultrasonography using a 7.5 MHz transducer. RESULTS: All study subjects were healthy, normotensive and had normal lipid profiles. The postmenopausal women showed a significantly greater blood pressure response to the mental arithmetic test than the premenopausal women or those taking estrogen replacement therapy (P < 0.01). Norepinephrine induced significant dose-dependent vasoconstriction in all three groups (P < 0.001). The postmenopausal women showed significantly greater constriction in response to norepinephrine than the premenopausal women and those taking estrogen replacement therapy (P = 0.02). Premarin significantly attenuated the norepinephrine-induced vasoconstriction in the postmenopausal women (P< 0.001). CONCLUSION: Healthy, normotensive postmenopausal women showed an exaggerated blood pressure response to mental stress. An increased vasoconstriction in response to norepinephrine and loss of estrogen-mediated vasodilation may contribute to the increased blood pressure response to stress in postmenopausal women without estrogen replacement therapy. 相似文献
102.
A. A. Izzo Nicola Mascolo Francesco Capasso 《Naunyn-Schmiedeberg's archives of pharmacology》1998,357(6):677-681
The effect of selective phosphodiesterase (PDE) inhibitors was studied on neural transmission within the enteric nervous system
employing a two-compartment bath (containing the oral and the anal end of a segment of guinea-pig ileum, respectively). Ascending
excitatory enteric nerve pathways were activated by electrical field stimulation (10 Hz for 2 s, 45 mA, 0.5 pulse duration)
in the anal compartment and the resulting contraction of the intestinal circular muscle in the oral compartment was recorded.
The partitioned bath enables PDE inhibitors and other drugs to be applied to enteric nerve pathways (in the anal compartment)
without interfering with the recording of the smooth muscle contraction in the oral compartment. The PDE 4 inhibitors rolipram
(0.01–10 μM) and Ro-20-1724 (0.01–10 μM) significantly (P<0.01) inhibited (10–91% and 9–83%, respectively) the nerve-mediated contractions. When both rolipram and Ro-20-1724 were
tested after phentolamine (1 μM) or yohimbine (0.1 μM), they were significantly (P<0.01) less effective. By contrast prazosin (1 μM) was ineffective. Vinpocetine (50 μM), milrinone (30 μM) and zaprinast
(100 μM), which inhibit PDE 1, 3 and 5, respectively, did not modify the nerve-mediated contractions. 8-Bromoadenosine 3’,5’-cyclic
monophosphate (8-Br-cyclic AMP) or N6,2’-O-dibutyryladenosine 3’,5’ cyclic monophosphate (dibutyryl cyclic AMP), two analogues of cyclic AMP, at lower concentrations
(0.1–1 μM) significantly (P<0.01) inhibited (15–73% and 5–49%, respectively) the nerve-mediated contractions, while at higher concentrations (10–100
μM) they caused a significant (P<0.01) potentiating (48–68% and 77–78%, respectively) effect. These results indicate that inhibition of PDE 4 (but not PDE
1, PDE 3 or PDE 5) produces a depression of neural transmission within the enteric nervous system, possibly by releasing noradrenaline
acting at α2-adrenoceptors on enteric neurons.
Received: 21 November 1997 / Accepted: 11 March 1998 相似文献
103.
Alzheimer disease (AD), the most common dementia of the elderly, results from a significant loss of neuronal cells in brain regions important in memory and cognition. Several lines of evidence suggest that the Aβ peptide is directly responsible for some of this neuronal cell death. We review recent evidence from in vitro toxicity and immunohistochemical studies that suggest some of the cell loss in AD is the result of apoptosis. 相似文献
104.
The authors performed a prospective, comparative study of 96 patients (age, 41-87 years) with femoropopliteal artery occlusions. Laser-assisted angioplasty was performed in 64 patients with 9- and 7-F over-the-wire multifiber catheters. Supplemental balloon dilation was performed after laser angioplasty. Thirty-two patients underwent excimer laser angioplasty (ELA), and 32 underwent pulsed dye laser angioplasty (DLA). The remaining 32 patients underwent conventional balloon angioplasty (BA). The length of occlusions was 3-10 cm (mean, 6.3 cm). Lesion characteristics in the three patient groups were similar. Technical success rates were 84% for ELA, 78% for pulsed DLA, and 81% for conventional BA. The 1-year clinical success rate was 69% (22 of 32 patients) in the ELA group, 63% (20 of 32 patients) in the pulsed DLA group, and 66% (21 of 32 patients) in the BA group (differences were not significant). Laser-assisted angioplasty with multifiber catheters in femoropopliteal artery occlusions did not help improve the technical success rate and 1-year clinical success rate when compared with those of conventional BA. 相似文献
105.
106.
Selectivity of neural stimulation in the auditory system: a comparison of optic and electric stimuli
Izzo AD Suh E Pathria J Walsh JT Whitlon DS Richter CP 《Journal of biomedical optics》2007,12(2):021008
Pulsed, mid-infrared lasers were recently investigated as a method to stimulate neural activity. There are significant benefits of optically stimulating nerves over electrically stimulating, in particular the application of more spatially confined neural stimulation. We report results from experiments in which the gerbil auditory system was stimulated by optical radiation, acoustic tones, or electric current. Immunohistochemical staining for the protein c-FOS revealed the spread of excitation. We demonstrate a spatially selective activation of neurons using a laser; only neurons in the direct optical path are stimulated. This pattern of c-FOS labeling is in contrast to that after electrical stimulation. Electrical stimulation leads to a large, more spatially extended population of labeled, activated neurons. In the auditory system, optical stimulation of nerves could have a significant impact on the performance of cochlear implants, which can be limited by the electric current spread. 相似文献
107.
Regulation of calcium channel expression in neonatal myocytes by catecholamines. 总被引:2,自引:0,他引:2
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T Maki E J Gruver A J Davidoff N Izzo D Toupin W Colucci A R Marks J D Marsh 《The Journal of clinical investigation》1996,97(3):656-663
Expression of the dihydropyridine (DHP) receptor (alpha 1 subunit of L-type calcium channel) in heart is regulated by differentiation and innervation and is altered in congestive heart failure. We examined the transmembrane signaling pathways by which norepinephrine regulates DHP receptor expression in cultured neonatal rat ventricular myocytes. Using a 1.3-kb rat cardiac DHP receptor probe, and Northern analysis quantified by laser densitometry, we found that norepinephrine exposure produced a 2.2-fold increase in DHP receptor mRNA levels at 2 h followed by a decline to 50% of control at 4-48 h (P < 0.02). The alpha-adrenergic agonist phenylephrine and a phorbol ester produced a decline in mRNA levels (8-48 h). The beta-adrenergic agonist isoproterenol and 8-bromo-cAMP produced a transient increase in mRNA levels. After 24 h of exposure to isoproterenol, 3H-(+)PN200-110 binding sites increased from 410 +/- 8 to 539 +/- 39 fmol/mg (P < 0.05). The number of functional calcium channels, estimated by whole-cell voltage clamp experiments, was also increased after 24 h of exposure to isoproterenol. Peak current density (recordings performed in absence of isoproterenol) increased from -10.8 +/- 0.8 (n = 23) to -13.9 +/- 1.0 pA/pF (n = 27) (P < 0.01). Other characteristics of the calcium current (voltage for peak current, activation, and inactivation) were unchanged. Exposure for 48 h to phenylephrine produced a significant decline in peak current density (P < 0.01). We conclude that beta -adrenergic transmembrane signaling increases DHP receptor mRNA and number of functional calcium channels and that alpha - adrenergic transmembrane signaling produces a reciprocal effect. Regulation of cardiac calcium channel expression by adrenergic pathways may have physiological and pathophysiological importance. 相似文献
108.
109.
A Clinical Trial with Brazilian Arnica (Solidago chilensis Meyen) Glycolic Extract in the Treatment of Tendonitis of Flexor and Extensor Tendons of Wrist and Hand
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Ary Gomes da Silva Elbe Rodrigues Machado Leonardo Mendes de Almeida Ricardo Marcelo Menezes Nunes Patrícia Caldeira Pena Giesbrecht Regina Mamed Costa Helber B. Costa Wanderson Romão Ricardo Machado Kuster 《Phytotherapy research : PTR》2015,29(6):864-869
One of the Brazilian arnicas, Solidago chilensis Meyen, is a species of the Asteraceae family. This plant is known by this common name because it shares remarkably similar organoleptic properties with the genus Arnica L., also within the family Asteraceae. We examined the effectiveness of the S. chilensis fluid extract used externally for treating tendinitis of flexor and extensor tendons of wrist and hand in placebo‐controlled double‐blind clinical pharmacological studies. This study was approved by the Ethical Committee for Scientific Research in Human Beings at University Vila Velha‐UVV. Two daily skin applications on the arm skin of a gel cream containing a 5% glycolic plant extract were administered to eight volunteers for 21 days. Among the volunteers, one of their arms was used as the placebo group, and the other one was used as a test group. Statistical data analyses demonstrated a significant reduction in the perception of pain in the arms in the test group, when it was compared to those receiving only the placebo. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
110.