全文获取类型
收费全文 | 2783篇 |
免费 | 110篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 17篇 |
妇产科学 | 12篇 |
基础医学 | 193篇 |
口腔科学 | 34篇 |
临床医学 | 130篇 |
内科学 | 187篇 |
皮肤病学 | 36篇 |
神经病学 | 113篇 |
特种医学 | 38篇 |
外科学 | 75篇 |
综合类 | 295篇 |
预防医学 | 221篇 |
眼科学 | 12篇 |
药学 | 1268篇 |
6篇 | |
中国医学 | 231篇 |
肿瘤学 | 67篇 |
出版年
2023年 | 17篇 |
2022年 | 39篇 |
2021年 | 60篇 |
2020年 | 58篇 |
2019年 | 43篇 |
2018年 | 57篇 |
2017年 | 60篇 |
2016年 | 62篇 |
2015年 | 67篇 |
2014年 | 199篇 |
2013年 | 229篇 |
2012年 | 198篇 |
2011年 | 265篇 |
2010年 | 174篇 |
2009年 | 136篇 |
2008年 | 130篇 |
2007年 | 130篇 |
2006年 | 91篇 |
2005年 | 91篇 |
2004年 | 78篇 |
2003年 | 92篇 |
2002年 | 86篇 |
2001年 | 37篇 |
2000年 | 39篇 |
1999年 | 30篇 |
1998年 | 28篇 |
1997年 | 30篇 |
1996年 | 16篇 |
1995年 | 21篇 |
1994年 | 28篇 |
1993年 | 24篇 |
1992年 | 23篇 |
1991年 | 18篇 |
1990年 | 21篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 25篇 |
1986年 | 21篇 |
1985年 | 40篇 |
1984年 | 21篇 |
1983年 | 16篇 |
1982年 | 24篇 |
1981年 | 18篇 |
1980年 | 15篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 12篇 |
1975年 | 6篇 |
1973年 | 3篇 |
排序方式: 共有2940条查询结果,搜索用时 15 毫秒
1.
2.
William A. Corrigall Mary Ann Linseman RoseMarie D'Onofrio Hau Lei 《Psychopharmacology》1986,89(3):327-333
A previously reported paradigm in which rats run down a runway for food reward followed by morphine injection was analyzed to assess the utility of the paradigm in studies of opiate reinforcement. One experiment replicated the original report that post-trial morphine caused both an increase in runway speed and a decrease in food consumption (taste aversion) over successive trials, and showed in addition that the increase in runway speed did not occur as a result of food deprivation alone, but required the animals to have consumed food in the goal box. A second study using the quaternary opiate antagonist methyl naltrexone to block the peripheral effects of morphine suggested that the increase in runway speed has a peripheral locus while the taste aversion has a central one. A third experiment in which morphine was microinjected into either the lateral ventricle or the ventral tegmental area supported these observations, in that intracranial morphine failed to result in an increased runway speed, but did produce taste aversion after microinjection into either site. These findings also suggest that the increase in runway speed caused by post-trial morphine in this experiment has a peripheral locus of effect, which is probably distinct from the central effect that supports morphine self-administration and conditioned place preference.
Offprint requests to: W.A.CorrigallThe views expressed in this publication are those of the authors and do not necessarily reflect those of the Addiction Research Foundation 相似文献
3.
L. Marzio F. Di Felice V. Celiberti O. Pieramico L. Grossi M. DiGioacchino B. P. Imbimbo F. Cuccurullo 《European journal of clinical pharmacology》1990,39(4):369-372
Summary To evaluate the influence of the stomach and the cholinergic system on gallbladder contraction induced by physiological stimuli, the reduction in gallbladder volume in 7 healthy volunteers has been studied by real-time ultrasonography after the oral and intraduodenal administration of olive oil, preceded by pretreatment with cimetropium bromide or placebo. After an overnight fast, each subject swallowed 50 ml olive oil or it was administered through a naso-duodenal tube in the proximal duodenum. Cimetropium bromide 5 mg or placebo was given intravenously under double-blind control.After the placebo pretreatment, gallbladder contraction was greater and faster after intraduodenal oil than after oral oil. Cimetropium bromide decreased the extent, velocity and duration of gallbladder contraction induced by intraduodenal olive oil but it only reduced the velocity of the contraction induced by oil given orally.It is concluded that in normal human subjects the stomach modulates the extent and velocity of postprandial gallbladder contraction and that anticholinergic agents antagonize the gastric and duodenal phases of the response of the gallbladder to a meal. 相似文献
4.
RITA PEREGO LUIGIA GOZZINI EMANUELE ARLANDINI GIORGIO BOLIS ROBERTO DE CASTIGLIONE 《Chemical biology & drug design》1995,46(5):341-345
Endothelin-1 (ET), the most potent vasoconstrictor yet discovered, is a peptide containirig 21 amino acids with two intrachain disulfide bridges. With the aim of obtaining two-chain derivatives, Et was submitted to chemical and enzymatic treatments. Reaction of ET with CNBr in 70% HCOOH gave, in addition to the expected [Hse7 lactone]-7,8-seco-ET and unreacted material, a by-product whose molecular weight was 25 m.u. greater than that of ET. When the reaction mixture, after lyophilisation, was immediately quenched with NH3-saturated dry MeOH, two products could be recovered in a 5:1 ratio, both obtained by nucleophilic attack of the homoserine lactone: the expected [Hse7-NH2]-7,8-seco-ET and [Hse7]ET, resulting from competitive intramolecular reaction of the deprotonated α-amino group of the Asp8 residue. The Lys9-Glu10 bond turned out to be very resistant to enzymatic attack both by Lys-C-endopeptidase and trypsin. The 9,10-seco-ET derivative could be obtained by treatment with Lys-C-endopeptidase only by using a high enzyme/ET ratio and after a prolonged incubation time. Cleavage of the Lys9-Glu10 bond could not be achieved by treatment with trypsin, even with a high enzyme/substrate ratio. The main product was 13, 14-seco-ET, deriving from the action of chymotripsin (present as an impurity in the trypsin preparation) on Tyr13. The structure of these peptides was confirmed by amino-acid sequence analysis and fast atom bombardment mass spectrometry (FAB-MS). Nicking of the ET structure at different positions had different impact on the biological properties of the resulting derivatives. © Munksgaard 1995. 相似文献
5.
A. Green 《Diabetologia》1987,30(3):188-192
Summary To determine whether adenosine is involved in long-term regulation of glucose transport in adipose tissue, we have investigated effects of administration of an adenosine receptor antagonist (theophylline) on adipocyte glucose transport. Rats were injected with theophylline (30 mg/kg, dissolved in 0.9% NaCl) daily for 7 days. Controls were injected with saline. The rats were then killed, and epididymal adipocytes were isolated. Insulin-stimulated glucose transport rates were decreased by about 25%–30% in the cells from theophylline-treated rats at all insulin concentrations tested. The half-maximally effective concentration of insulin was not altered (6.5±0.5 and 6.7±0.5 mU/l in control and treated cells respectively), suggesting a post-insulin binding defect. This was confirmed by the finding that 125I-insulin binding to the cells was not altered. Adenosine receptor number and affinity (measured on detergent-solubilized adipocyte extracts using 125I-hydroxyphenylisopropyl adenosine) was also not changed by theophylline treatment. We conclude that theophylline administration causes decreased glucose transport rates in rat adipocytes at a post-insulin binding level. Thus, chronic adenosine receptor blockade impairs adipocyte glucose transport, suggesting that adenosine is involved in long-term regulation of glucose metabolism in adipose tissue. 相似文献
6.
MOTOYOSHI NOMIZU YOSHIMASA INAGAKI TAKEYOSHI YAMASHITA AKO OHKUBO AKIRA OTAKA NOBUTAKA FUJII PETER P. ROLLER HARUAKI YAJIMA 《Chemical biology & drug design》1991,37(2):145-152
A new two-step deprotection/cleavage procedure for t-butoxycarbonyl (Boc) based solid phase peptide synthesis is reported. First the protective groups are removed from 4-(oxymethyl)-phenylacetamidomethyl (PAM) resin attached peptide with the weak hard acid, trimethylsilyl bromide-thioanisole/trifluoroacetic acid (TFA). In the second step, the peptide is cleaved from the resin with a stronger hard acid such as trimethylsilvl trifluoromethanesulfonate in TFA or with HF. The method is also shown to deformylate Nin-formyltryptophan moiety efficiently. The usefulness of this procedure for practical solid phase peptide synthesis is demonstrated by comparison with other deprotection methods in the synthesis of urotensin II and human endothelin. 相似文献
7.
甲基叔丁基醚无铅汽油肾脏毒性的实验研究 总被引:6,自引:0,他引:6
目的:了解甲基叔丁基醚(MTBE)无铅汽油对肾脏的毒性及毒作用机制。方法:昆明种小鼠经呼吸道静式染毒,MTBE无铅汽油22.9、11.4及2.3g/m^3每天一次,连续2h,共22d亚急性染毒。日立-7150型全自动生化仪检测血清中尿素氮(BUN)、肌酐(Cr)含量;肾组织均浆中丙二醛(MDA)和超氧化物歧化酶(SOD)含量分别用荧光法,邻苯三酚自氧化固定时间法测定;电镜观察肾皮质区超微结构的变化,结果:22.9g/m^3染毒组雌性小鼠血清中BUN含量与阴性对照组间比较差异有显著性(P<0.05);电镜观察到22.9g/m^3染色毒对照组雌雄性小鼠的肾小球基底膜,肾小管细胞线粒体及绒毛均未见显著异常改变。结论:MTBE无铅汽油对肾小球的滤过功能有一定的影响,雌性小鼠可能更为敏感。 相似文献
8.
Patrice Venault Georges Chapouthier Jacques Simiand Robert H. Dodd Jean Rossier 《Brain research bulletin》1987,19(3)
Benzodiazepines are known to induce a profound anterograde amnesia in man. In this report, it is shown that methyl β-carboline-3-carboxylate (β-CCM), an inverse agonist of the benzodiazepine receptor, has the opposite effect; it enhances performance in learning and memory tasks. Three different learning models were used: habituation to a new environment and passive avoidance in mice and imprinting in chicks. The opposite effects of both β-CCM and the benzodiazepine diazepam were blocked by administration of the benzodiazepine receptor antagonist Ro 15-1788, provicling evidence that the benzodiazepine receptor is involved in these effects. 相似文献
9.
10.
T. Shioya M. Kagaya M. Sano M. Itaba T. Shindo M. Miura 《European journal of clinical pharmacology》1996,50(5):375-380
Objective:
We studied the bronchodilatory effect of tiquizium bromide [3-(di-2-thienylmethylene)-5-methyl-trans-quinolizidinium bromide; TQZ], an antimuscarinic agent, on airway smooth muscle in vitro, and also in patients with chronic
obstructive pulmonary disease (COPD).
Methods:
In the first experiment, canine tracheal smooth muscle was used to measure the pA2 of TQZ in vitro. The selectivity of TQZ
for muscarinic receptor subtypes was also examined with a radioligand binding assay.
Results:
The pA2 value of TQZ was 8.75. The pK
i values of TQZ for M1, M2, and M3 were 8.70, 8.94, and 9.11, respectively. In an open pilot experiment, the effects of TQZ
inhalation were studied in seven patients with COPD (seven men, mean age 68.5 years). TQZ significantly increased forced vital
capacity (FVC) and forced expiratory volume in 1 s (FEV1) in a dose-dependent manner. The mean maximum increases in FVC and FEV1 caused by inhaled TQZ (2.0 mg) were 24% and 29%, respectively, and they were measured 1 h after the drug had been inhaled.
The FVC and FEV1 were still significantly higher than the control values even 8 h after the drug had been inhaled. No adverse effects were
observed after inhalation of TQZ.
Conclusion:
These data suggest that TQZ is an effective antimuscarinic agent, and that it causes significant bronchodilation in patients
with COPD.
Received: 3 April 1995/Accepted in revised form: 27 November 1995 相似文献