首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1431篇
  免费   94篇
  国内免费   24篇
耳鼻咽喉   16篇
儿科学   39篇
妇产科学   10篇
基础医学   169篇
口腔科学   57篇
临床医学   220篇
内科学   235篇
皮肤病学   25篇
神经病学   80篇
特种医学   135篇
外科学   153篇
综合类   31篇
预防医学   215篇
眼科学   8篇
药学   97篇
肿瘤学   59篇
  2022年   8篇
  2021年   18篇
  2019年   12篇
  2018年   11篇
  2017年   15篇
  2016年   15篇
  2015年   21篇
  2014年   27篇
  2013年   43篇
  2012年   33篇
  2011年   42篇
  2010年   43篇
  2009年   52篇
  2008年   33篇
  2007年   54篇
  2006年   51篇
  2005年   55篇
  2004年   47篇
  2003年   47篇
  2002年   40篇
  2001年   37篇
  2000年   27篇
  1999年   27篇
  1998年   40篇
  1997年   44篇
  1996年   38篇
  1995年   35篇
  1994年   16篇
  1993年   25篇
  1992年   18篇
  1991年   31篇
  1990年   27篇
  1989年   30篇
  1988年   34篇
  1987年   34篇
  1986年   21篇
  1985年   26篇
  1984年   11篇
  1983年   17篇
  1982年   15篇
  1981年   11篇
  1980年   15篇
  1978年   17篇
  1977年   10篇
  1976年   14篇
  1974年   8篇
  1929年   17篇
  1928年   8篇
  1924年   8篇
  1922年   9篇
排序方式: 共有1549条查询结果,搜索用时 15 毫秒
1.
2.
用混合粘合剂碳糊电极测定丁螺环酮   总被引:6,自引:1,他引:5  
用混合粘合剂碳糊电极测定丁螺环酮张正奇,曾鸽鸣,刘传桂,黎艳飞(湖南大学化学化工系,长沙410082)碳糊电极无毒,制作方便,表面更新容易,应用电位范围广,在药物分析中已有应用[1~5]。我们在液体石腊中加入添加剂,组成混合粘合剂,可显著改善电极的检...  相似文献   
3.
4.
Org 20781, the major metabolite of Org 7797 found in in-vitro experiments was examined for antiarrhythmic and electrophysiological effects in-vivo. Org 20781 (0·5–2·0 mg kg?1 i.v.) inhibited the development of early ischaemia-induced arrhythmias in rats, suppressed spontaneous ventricular tachycardia (VT) in conscious dogs with 24-h old infarcts, and prevented electrical induction of VT in dogs with 5–6-day old infarcts, actions associated with slowing of conduction at all levels of the myocardium. Cardiac refractory periods were only modestly prolonged whilst repolarization was unchanged. Peak plasma levels of the parent compound (infused to total doses of 2–4mg kg?1) associated with suppression of late arrhythmias were 6–18 μm, whilst the mean plasma elimination half-life (in normal dogs) was 107 min. It was concluded that the major metabolite has a similar antiarrhythmic and electrophysiological profile to the parent compound, is at least half as potent and may contribute to the therapeutic effects of Org 7797 administration.  相似文献   
5.
The acute effects of monoamine oxidase inhibitors L-deprenyl (0.5-5.0 mg/kg), clorgyline (1.0-10.0 mg/kg), and milacemide (100-400 mg/kg) on the behavior of adult male squirrel monkeys were examined during brief social separations beginning 60 min after subcutaneous drug administration. All three drugs selectively reduced the rate of calling during social separation at doses which did not affect time spent in locomotion, nor the frequency of vigilance-checking. Deprenyl and milacemide, but not clorgyline, produced concurrent decreases in locomotion at the higher doses tested. At threshold doses, clorgyline, but not deprenyl or milacemide, increased call duration and decreased call peak frequency compared to vehicle control values. Plasma levels of MHPG were decreased by an optimal dose of clorgyline but not by deprenyl or milacemide, indicating that substrate specificity was maintained at the drug doses employed. We conclude that different MAO substrates mediate different aspects of vocal and nonvocal behavior in adult male squirrel monkeys.  相似文献   
6.
Introduction   Fibrosis is a component of many tissue pathologies leading to loss of normal tissue function, primarily due to excessive collagen deposition. Collagen is deposited following cleavage of the C- and N- terminal peptides from the pro-collagen molecule. The cleavage of the globular C-peptide by PCP reduces solubility of the fibrillar collagen molecule, resulting in deposition of insoluble collagen. Increased insoluble collagen deposition is a feature of all organ fibroses, with inhibition of this process, a key potential anti-fibrotic mechanism. The aim of this work was to discover potent and selective PCP inhibitors as experimental, topically applied, anti-fibrotic drugs for clinical evaluation.
Materials and methods   PCP was cloned from human osteosarcoma cells and enzymatic activity demonstrated using a PCP-specific peptide cleavage assay. Activities were confirmed by measuring cleavage of [3H]C-peptide from type-I pro-collagen. A cell-based fibroplasias model was employed to demonstrate compound efficacy using collagen deposition, liberated C-peptide and histological endpoints. The activities of PCP inhibitors in fibroblast and epithelial in vitro cell proliferation and migration assays, and selectivity vs. a panel of MMPs were also determined.
Discussion   In summary, we have identified and characterized potent and selective inhibitors of PCP for progression to clinical studies for investigation as a treatment paradigm for fibrotic disease.  

  Results  相似文献   

7.
BACKGROUND: Modulation of the acoustic startle response by aversive sensory stimulation is a simple and objective indicator of emotionality in rodents and human beings that has been extremely valuable for the analysis of neural systems associated with fear and anxiety. We have described a paradigm for measuring fear-potentiated, whole-body acoustic startle in nonhuman primates and have developed a protocol for maintaining fear-potentiated startle over repeated sessions with minimal extinction to allow measurement of pharmacological effects on fear-potentiated startle by using within-subjects designs in relatively small groups of monkeys. METHODS: A novel, within-subjects testing protocol was used to examine the effects of three compounds in rhesus monkeys that have anxiolytic effects in rodents on fear-potentiated startle but that differ in their mechanism of action. Spontaneous vocalizations during testing also were recorded. Juvenile monkeys that were trained to associate a visual stimulus with a fear-inducing air blast to the face were tested after acute administration of different doses of buspirone diazepam, morphine, or vehicle. RESULTS: Monkeys rapidly developed a robust and persistent elevation of startle response in the presence of the CS during repeated testing sessions. Diazepam and morphine produced dose-related reductions of fear-potentiated startle. Buspirone did not significantly reduce fear-potentiated startle at the doses tested, although a trend was evident at the highest dose. All drugs reduced rates of coo vocalizations during startle testing. CONCLUSIONS: These fear-potentiated startle results suggest that rhesus monkeys have a pharmacological profile with respect to these compounds that is closer to humans than to rats. This demonstrates the value of examining the effects of drugs on fear-potentiated startle in nonhuman primates.  相似文献   
8.
Y Niv  C Turani  E Kahan  GM Fraser 《Gastroenterology》1997,112(6):2104-2107
Polycystic kidney disease is an autosomal dominant disease that may be associated with cystic disease of the liver. In women, the cysts may develop early and be more troublesome than in men. Cystadenocarcinoma of the pancreas is uncommon, comprising 1% of primary pancreatic malignancies. This case report is the first to describe a familial association between polycystic kidney disease and cystadenocarcinoma of the pancreas and liver in the English medical literature. A patient with autosomal dominant polycystic kidney disease (ADPKD) and multiple hepatic cysts developed cystadenocarcinoma of the pancreas with multiple malignant liver cysts. The patient's mother, sister, and niece had ADPKD, and the patient's sister also died of pancreatic cystadenocarcinoma. We believe that the development of these two disease entities in which the primary pathology is cyst formation has a genetic association. (Gastroenterology 1997 Jun;112(6):2104-7)  相似文献   
9.
10.
1. Rat pups emit ultrasonic calls during brief episodes of social separation. These calls have been variously described as “distress” calls and may be related to the separation cries expressed by the young of many mammalian species.

2. Ultrasonic call of rat pups are modulated by environmental stimuli such as ambient temperature, olfactory and tactile stimuli associated with the nest.

3. Calls are also sensitive to a variety of purported anxiolytic and anxiogenic drugs, including the benzodiazepines, serotonin agonists, and ligands at the NMDA-glycine receptor complex.

4. In addition to providing a simple test for the anxiolytic properties of drugs, this model may also provide new insights about the development and neurobiology of anxiety.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号