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1.
Various neural factors are involved in the suckling-induced increase in serum growth hormone (GH) levels in neonatal rats, and, in the present study the serotonergic, cholinergic, somatostatin and GH-releasing hormone (GHRH) systems were investigated. The serotonin (5-HT) precursor 5-hydroxy-L-tryptophan (5-HTP) and the 5-HT receptor agonist quipazine maleate stimulated serum GH levels in 2-day-old rat pups separated from their mothers for 6 h. The increase in serum GH during suckling was further elevated by 5-HTP. The 5-HT antagonist cyproheptadine decreased serum GH levels in separated 2-day-old pups, and although it reduced the amplitude of the suckling-induced increase in serum GH concentration, it did not alter the increase in serum GH on a percentage basis. The effect of the cholinergic muscarinic antagonist atropine sulfate (ATR) was similar to that of cyproheptadine. Moreover, in separated pups, ATR prevented the increase in serum GH induced by 5-HTP. In contrast with 2-day-old pups, ATR completely eliminated the suckling-induced release of GH in 10-day-old rats. However, ATR failed to prevent GH release induced by the α2-adrenergic agonist clonidine HCI in 10-day-old male pups. While thyrotropin-releasing hormone increased serum GH levels, rat GHRH failed to alter serum GH levels either in separated or in suckled 2-day-old rat pups. Immunoneutralization for rat GHRH eliminated the increase in serum GH induced by clonidine HCI in 10-day-old pups, but (on a percentage basis) failed to prevent the GH-increasing effect of suckling in 2-day-old pups. While somatostatin failed to significantly decrease serum GH in separated 2-day-old pups, it effectively decreased serum GH levels in 2-day-old pups which were suckled. Cysteamine, which depletes hypothalamic somatostatin, increased serum GH in separated 2-day-old pups, and further increased the suckling-induced levels of serum GH. Cysteamine partially prevented the GH-decreasing effect of ATR. The present findings suggest that 1) the serotonergic and cholinergic systems are involved in the regulation of GH secretion as early as day 2 postpartum; 2) the serotonergic and cholinergic systems modulate the basal, and do not modulate the suckling-induced levels of serum GH; 3) the serotonergic system may exert its stimulatory influence on GH secretion only in the presence of a functional muscarinic cholinergic system; 4) the cholinergic system, at least in part, stimulates GH secretion via a cysteamine-sensitive system (probably by inhibiting somatostatin); 5) the cholinergic system is not functionally coupled with the α2-adrenergic system, which stimulates GH secretion via rat GHRH; 6) since in 10-day-old pups clonidine HCI was effective only in males, while suckling was effective in both sexes, the α2-adrenergic system is not involved in the suckling-induced increase of serum GH; and finally 7) neither somatostatin nor rat GHRH seem to be involved in the suckling-induced changes in serum GH. The findings are consistent with the hypothesis that the high circulating GH levels in the neonatal rat are due to alternative GH-releasing factors, perhaps thyrotropin-releasing hormone or γ-aminobutyric acid. The neurohumoral mediator of the suckling-induced GH release in neonatal rats remains to be identified. 相似文献
2.
The effects of cysteamine on the upper gastrointestinal tract of children with cystinosis 总被引:1,自引:0,他引:1
The purpose of this study was to evaluate the effects of cysteamine on gastric acid output and serum gastrin levels in children
with nephropathic cystinosis. We studied four children with nephropathic cystinosis receiving a dose of free base cysteamine
of 14.35 mg/kg four times a day (range 12.30 – 18.80 mg/kg). Gastric acid was measured for the hour before and after administration
of the medication. Serum gastrin levels were obtained at 0, 30, 60, and 90 min following the medication. Gastrointestinal
anatomy was evaluated by endoscopy and biopsy. Following administration of the medication, all subjects showed an increase
in gastric acid output. Mean acid output increased from 0.79 to 2.22 mEq/h. Mean gastric acid output adjusted for body weight
increased from 0.03 to 0.09 mEq/kg per hour. Following administration of the medication, all subjects showed an increase in
serum gastrin. The mean increase above the base value was 38.3 pg/dl. Two of the four subjects demonstrated visual and histological
evidence of inflammation. Cysteamine has a marked effect on gastric acid production and serum gastrin, even at the dose used
in children with nephropathic cystinosis. The clinical effect of this acid production is unknown but may be significant.
Received February 13, 1996; received in revised form February 25, 1997; accepted February 27, 1997 相似文献
3.
J. Chuang M. -T. Lin S. -A. Chan S. -J. Won 《Pflügers Archiv : European journal of physiology》1990,415(5):606-610
The changes in thermoregulatory effectors produced by an injection of polyriboinosinic acid: polyribocytidylic acid (Poly
I:C) or interferon were assessed and compared in control rats, in rats with hypothalamic somatostatin (SS) receptor blockade
and in rats with hypothalamic SS depletion. Intrahypothalamic (i.h., 0.05–0.50 μg) or intraperitoneal (i.p., 100–600 μg) administration
of Poly I:C caused a dose-related rise in colon temperature in control rats at all ambient temperatures (Ta) studied. A Poly I:C-induced fever was produced by increased metabolism at a Ta of 8 °C, whereas at 30 °C, it was caused by cutaneous vasoconstriction. At a Ta of 22 °C, the fever was caused by increased metabolism and cutaneous vasoconstriction. On the other hand, i.h. administration
of SS-14 antagonist (0.1–0.5 ng) caused a dose-related fall in colon temperature at Ta of 8 °C or 22 °C. At a Ta of 8 °C, the hypothermia was caused by decreased metabolism, whereas at 22 °C, it was caused by decreased metabolism and
cutaneous vasodilation. At a Ta of 30 °C, the thermoregulatory effectors were not affected by SS-14 antagonist treatment. Furthermore, the fever induced
by Poly I:C or interferon was significantly reduced by pretreatment of rats with an i.p. dose of cysteamine (30 mg. kg−1) or an i.h. dose of SS-14 antagonist (0.1 ng). The results indicate that a somatostatinergic pathway in rat hypothalamus
may mediate the fever induced by interferon or its inducer Poly I:C. 相似文献
4.
Assadi FK McCue P Jefferis S Shi M Beckman DA 《Pediatric nephrology (Berlin, Germany)》1999,13(9):812-815
The safety of cysteamine after renal transplantation and during pregnancy is an important issue, since girls with cystinosis
are in better health on cysteamine therapy and thus more likely to become pregnant. In the first study, cysteamine was given
to pregnant rats on days 6.5–18.5 post conception in oral doses of 0, 37.5, 75, 100, and 150 mg/kg per day. The dams were
sacrificed on day 20.5, the fetal kidneys removed and prepared for histological examination. In the second study, cysteamine
was given to dams on days 6.5–19.5 post conception in oral doses of 0, 37.5, 50, and 75 mg/kg per day. Dams were allowed to
give birth naturally and pups were given cysteamine on days 4–21 to yield the same oral doses of cysteamine given to the dam.
Renal function was evaluated on day 35. Histological examination of fetal kidneys revealed no changes even in kidneys from
fetuses with growth retardation and malformations. Furthermore, there were no alterations in renal function in offspring on
day 35. These findings demonstrate that cysteamine therapy does not affect renal development in the rat. Further investigations
will be required to prove whether cysteamine therapy has the potential to affect renal development in the human.
Received: 25 September 1998 / Revised: 17 November 1998 / Accepted: 13 December 1998 相似文献
5.
Jahan Bakhsh Raoof Reza OjaniFereshteh Chekin 《Journal of electroanalytical chemistry (Lausanne, Switzerland)》2009,633(1):187-192
The functionalized carbon nanotube electrode was fabricated by electrodeposition of 1,2-naphthoquinone-4-sulfonic acid sodium (Nq) on single-wall carbon nanotube (SWNT) modified glassy carbon electrode (GCE). This electrode was characterized by scanning electron microscopy (SEM) and the results showed that Nq can rapidly and effectively be deposited on the surface of SWNT film with high stability. The electrochemical properties of functionalized SWNT/GCE with Nq (SWNT–Nq/GCE) were studied using cyclic voltammetry, double step potential chronoamperometry and differential pulse voltammetry methods. The results indicated that SWNT could improve the electrochemical behavior of Nq and greatly enhances its redox peak currents. The SWNT–Nq/GCE exhibited a pair of well-defined redox peaks. The experimental results also demonstrated that the Nq deposited species on SWNT could catalyze cysteamine oxidation and SWNT–Nq exhibited a high performance with lowering the overpotential by more than 710 mV. The effect of pH value, number of scans and Nq concentration were investigated on the electrochemical behavior of cysteamine. The selectivity of the reaction has been assessed with no interference from tyrosine, lysine, methionine, tryptophan, alanine and glutathione. The presented method has highly selectivity for voltammetric detection of cysteamine in the dynamic range from 5.0 × 10−6 M to 2.7 × 10−4 M and with a detection of limit (3σ) 3.0 × 10−6 M. 相似文献
6.
Rats were kindled by intraperitoneal injection of pentylenetetrazol (PTZ) (30 mg/kg) every 48 h. Once kindled, animals received a single injection of cysteamine (200 mg/kg) and subsequent responses to PTZ were observed. Cysteamine, an agent which depletes brain somatostatin and suppresses kindled seizures in amygdaloid-kindled rats, markedly suppressed the severity of PTZ-induced seizures in PTZ-kindled rats as well. However, it did not alter the convulsive response of non-kindled rats to a submaximal convulsive dose (50 mg/kg) of PTZ. The results support a role for somatostatin in kindling. 相似文献
7.
BACKGROUND: Calcium phosphate cements (CPCs) possess the bio-degradation and osteoconduction, and its final hydration product, hydroxyapatite, is the main inorganic constituent of bones. However, its poor mechanical property makes it unable to be used for repairing weight-bearing bone defects.
OBJECTIVE: To develop a kind of bioactive bone cements with decent biomechanical property and biocompatibility.
METHODS: 6% silk fibroin aqueous solutions containing different concentrations of N-acetylcysteine (0, 10 and 25 mmol/L) were prepared. Each cement sample was prepared by mixing the curing liquid and α-tricalcium phosphate powder with the ratio of 0.4 mL: 1 g; α-tricalcium phosphate powder mixed with ddH2O as control group. The compressive strength, setting time of the cements were measured. The crystal components of the cements were characterized using X-ray diffraction and the microstructure was observed using scanning electron microscope. MC3T3-E1 cells were seeded onto the material in each group, and cell morphology was observed under scanning electron microscope at 24 hours. MC3T3-E1 cells were cultured in the extract of each material, cell proliferation was detected at 1, 3, 5 and 7 days, and the lactate dehydrogenase level was detected at 1 and 3 days.
RESULTS AND CONCLUSION: X-ray diffraction and scanning electron microscope showed that the final hydration products of α-tricalcium phosphate in all specimens were hydroxyapatite. When the concentration of N-acetylcysteine was 25 mmol/L, the compressive strength of the material reached (49.39±1.68) MPa, with the initial setting time of (21.77±1.07) minutes and the final setting time of (31.88±1.69) minutes. There was no significant difference in cell morphology among cements. These results suggest that the cement containing N-acetylcysteine exhibites good biocompatibility and high mechanical strength. 相似文献
8.
9.
Cysteamine effects on somatostatin, catecholamines, pineal NAT and melatonin in rats 总被引:1,自引:0,他引:1
Susan M. Webb Thomas H. Champney Richard W. Steger Mary K. Vaughan Russel J. Reiter 《Brain research bulletin》1986,16(3):315-320
The thiol reagent cysteamine was administered to adult male rats with the aim of investigating its effect on different neural and pineal components. As expected, immunoreactive somatostatin decreased in the median eminence (ME) (p less than 0.05) and gastric antrum (p less than 0.05) after cysteamine; however, no significant change was observed in the pineal IRS content after drug treatment. A decrease in norepinephrine was observed in the ME (p less than 0.001), hypothalamus (p less than 0.001) and pineal gland (p less than 0.05), together with a rise in ME (p less than 0.005) and hypothalamic dopamine (p less than 0.005) content; these results are consistent with a dopamine-beta-hydroxylase inhibiting effect of cysteamine. No effect was observed on hypothalamic serotonin and 5-hydroxyindole-acetic acid content. Pineal N-acetyltransferase (NAT) activity was significantly higher (p less than 0.05) after cysteamine than after saline, but no statistically significant effect was observed on pineal melatonin content. The mechanism involved in the NAT rise is presumably not related to the known stimulatory effect of norepinephrine, which fell after cysteamine. It is suggested that cysteamine may act at an intracellular level, inhibiting NAT degradation, an effect demonstrated in vitro and thought to be related to a thiol:disulfide exchange mechanism. 相似文献
10.
A Russo J B Mitchell 《International journal of radiation oncology, biology, physics》1984,10(8):1243-1247
Cellular glutathione (GSH) levels were modulated by either inhibition of GSH synthesis by buthionine sulfoximine (BSO) or elevation of GSH by treatment with 2-oxo-thiazolidine-4-carboxylate (OTZ), cobaltous chloride, or cysteamine. Using these agents, X ray survival in air was assessed as a function of cellular GSH levels. Depletion of GSH by BSO to less than 5% of control values resulted in slight sensitization of the aerated curve. However, elevation of GSH by as much as 200 to 300% of controls provided no radioprotection in air. These data are discussed in the context of the role of GSH and GSH peroxidase in the detoxification of peroxides produced by X rays. 相似文献