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   16390篇
  免费   1034篇
  国内免费   1478篇
耳鼻咽喉   27篇
儿科学   320篇
妇产科学   63篇
基础医学   1866篇
口腔科学   255篇
临床医学   908篇
内科学   1291篇
皮肤病学   16篇
神经病学   1752篇
特种医学   312篇
外科学   924篇
综合类   5547篇
预防医学   617篇
眼科学   165篇
药学   3128篇
中国医学   1549篇
肿瘤学   162篇
  2023年   87篇
  2022年   126篇
  2021年   257篇
  2020年   329篇
  2019年   281篇
  2018年   232篇
  2017年   390篇
  2016年   465篇
  2015年   425篇
  2014年   837篇
  2013年   1038篇
  2012年   982篇
  2011年   1144篇
  2010年   898篇
  2009年   845篇
  2008年   943篇
  2007年   986篇
  2006年   919篇
  2005年   749篇
  2004年   666篇
  2003年   719篇
  2002年   563篇
  2001年   508篇
  2000年   413篇
  1999年   330篇
  1998年   283篇
  1997年   276篇
  1996年   265篇
  1995年   277篇
  1994年   226篇
  1993年   194篇
  1992年   211篇
  1991年   209篇
  1990年   153篇
  1989年   139篇
  1988年   127篇
  1987年   94篇
  1986年   87篇
  1985年   177篇
  1984年   162篇
  1983年   134篇
  1982年   155篇
  1981年   126篇
  1980年   116篇
  1979年   84篇
  1978年   63篇
  1977年   55篇
  1976年   46篇
  1974年   22篇
  1973年   26篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
大鼠肝移植术后并发症的预防   总被引:1,自引:0,他引:1  
李涛  孙星  彭志海 《肝胆胰外科杂志》2007,19(4):215-216,219
目的 探讨大鼠肝移植术后并发症的预防措施.方法 比较建立模型初期所行50例大鼠肝移植前20例(前组)与后30例(后组)的手术时间、无肝期、手术成功率、术后生存率及并发症.结果 与前组相比,后组供体手术时间、供体修整与套管安装时间、无肝期及受体手术时间明显缩短(P<0.05),手术成功率与术后3 d及7 d生存率明显提高(P<0.05),早期术后出血并发症明显减少(P<0.05),但胆道并发症差异无统计学意义(P>0.05).结论 掌握大鼠肝移植技术存在明显的学习曲线,熟练的手术操作及术后并发症的合理预防可提高手术成功率及术后大鼠生存率.  相似文献   
32.
Recently, Korean people are consuming seaweeds almost 3.5 times more now than three decades ago. It is well known that seaweeds contain lots of soluble dietary fiber in addition to micronutrients such as β-carotene, iodine and some bioactive components. Seaweeds are considered to be effective for preventing chronic diseases including obesity, diabetes mellitus, atherosclerosis, cancer or constipation. This study was conducted to investigate the effect of seamustard intake on body weight gain, blood glucose level and lipid profiles in rats fed diets with different energy nutrient composition. Male Sprague-Dawley rats (average initial weight 103.7 g) were divided into groups for two experiments as follows; Control, M2.5 & M5 groups (Exp. I) and M5, M10, HCM5, HCM10, HFM5 & HFM10 groups (Exp. II). The rats were fed diet and water ad libitum for 4 weeks. In general, there was no significant difference in blood glucose and triglyceride concentration among groups. In Exp. I, serum LDL-cholesterol level of rats fed diet with 5% seamustard powder (M5) was significantly lower than that of control group, while HDL-cholesterol level, TC/LDL ratio and weight of adrenal gland were higher. In Exp. II, food intake, body weight gain and EER of high fat diet with 10% seamustard group (HFM10) were the lowest among groups. Except gastrocnemius muscle, all organ weights of HFM10 group were the lowest. Fecal cholesterol excretion and serum LDL-cholesterol concentration of HFM10 group were the highest, while serum HDL-cholesterol level was the lowest among groups. Interestingly, HDL-cholesterol concentration was the highest in HCM5 group among groups. From these results, it was suggested that seamustard intake might be more effective for body weight control, but not for improving blood lipid profiles in high fat diet than in high carbohydrate diet.  相似文献   
33.
Compared with results obtained in locally anesthetized, paralyzed rats, the dissociative anesthetic ketamine did not alter either the number of spontaneously active striatal neurons or the basal firing rate of striatal neurons; 90% of these cells exhibited the type I striatal neuron waveform. Chloral hydrate anesthesia suppressed both the occurrence and the firing rate of spontaneously active type I cells, but did not alter the activity of type II striatal neurons. Cortical stimulation preferentially activated type II cells in paralyzed rats and in chloral hydrate-anesthetized rats. Thus, under dissociative anesthesia it is possible to study spontaneously active type I striatal neurons. However, a method of activation such as cortical stimulation is necessary to study type II striatal neurons.  相似文献   
34.
Purpose. The locomotive activity changes after intravenous (i.v.) administration of methylphenidate (MPD) in rats were pharmacodynamically analyzed. Methods. MPD concentration in plasma, MPD concentration and dopamine (DA) level in striatal dialysate collected by microdialysis method, and the locomotor activity after i.v. administration of MPD (2, 5 and 10 mg/kg doses) were used for the analysis. Results. The transport of MPD from plasma to the interstitial fluid in the brain could be expressed by the linear two-compartment model. The clockwise hysteresis between the MPD concentration and the DA level in the dialysate could be explained by the pharmacodynamic model considering Michaelis-Menten type reuptake process of the extracellular DA into the terminal of the dopaminergic nerve and its competitive inhibition by the extracellular MPD. The inhibition constant (Ki) of MPD for DA reuptake was estimated to be 41.3 ± 73.8 nM (mean ± SE), which was closely consistent with the in vitro value after correction with dialysis recovery. The relationship between DA level in dialysate and locomotor activity was expressed by the Emax model considering two contrary effects, hyperkinesia and stereotypy. The bi-phasic locomotor activity-time profiles after high dose of MPD could be represented by this model. Conclusions. The developed model made it possible to explain the tolerance in DA increase and the complicated locomotive change induced by MPD, and may be useful for other DA reuptake inhibitors, such as amphetamine and methamphetamine.  相似文献   
35.
用自制液压冲击颅脑损伤仪对大鼠的头部由轻到重的4种冲击力产生4级脑损伤。1级可以无明显病理生理变化;2~4级则随冲击力的加重病理生理变化亦加重。这些变化包括心率,呼吸,血压,颅内压,脑水份含量与伊文思蓝蓝染范围测定以及病理学的变化。  相似文献   
36.
Spontaneously hypertensive (SHR) and salt-loaded hypertensive rats (SLHR) were submitted to a daily treatment by gavage of 2 mL/100 g body weight of the aqueous extract of the stem of Ipomoea acanthocarpa (30 mg/mL stock solution). A fall in blood pressure of nearly 13% was observed after two successive administrations of the aqueous extract. After 14 days of treatment, the blood pressure fell by more than 30±8%. The hypotensive effect might be due to a direct vascular smooth muscle effect or to its already observed high diuretic effects or might be acting by some other mechanism.  相似文献   
37.
肺脏在老龄大鼠多器官衰竭中的作用   总被引:3,自引:0,他引:3  
目的:探讨肺脏在老龄大鼠多器官衰竭中的作用。方法:一次性静脉主射大肠杆菌内毒素,复制出老龄大鼠多器官衰竭(MOF)实验模型。动态观察了五个时相组(1、2,6、12,24h)的有关免疫,生化功能指标和病理变化。  相似文献   
38.
大鼠肝细胞Ⅰ,Ⅲ型前胶原基因表达及PDGF的影响   总被引:3,自引:1,他引:2  
目的观察大鼠肝细胞Ⅰ,Ⅲ型前胶原基因的表达及PDGF对其表达的影响.方法应用原位杂交技术检测分离培养的SD大鼠肝细胞(n=30)内Ⅰ,Ⅲ型前胶原基因的表达.同时观察10μg/L(n=30)和30μg/L(n=30)PDGF促进前胶原基因表达的作用.测定基因表达颗粒总面积占细胞总面积的百分比,并作比较分析.结果无论正常肝细胞或是在两种浓度的PDGF存在时,肝细胞内均可见到Ⅰ,Ⅲ型前胶原基因的表达.正常肝细胞Ⅰ,Ⅲ型前胶原基因表达面积的百分比(%)为77±19和75±21;加10μg/LPDGF后为115±19和112±10,而加30μg/L后为152±34及181±28,且在后者中表达明显增强(P<005及P<001).结论PDGF在转录水平上促进肝细胞胶原的合成.  相似文献   
39.
补肾中药对雄激素致不孕大鼠卵巢核仁组成区蛋白的影响   总被引:4,自引:0,他引:4  
观察补肾中药对雄激素致不孕大鼠卵巢核仁组成区蛋白的影响。用SD雌性大鼠幼仔,出生9d龄注射丙酸睾丸酮,制成雄激素致不孕大鼠(ASR)模型。80d龄灌服补肾中药水溶液两周。100d龄心脏灌注处死。以核仁组成区蛋白嗜银染色(AgNOR)和增殖细胞核杭原(PcNA)为指标,观察卵巢颗粒细胞、间质腺细胞的形态学变化。结果:补肾中药能够使ASR卵巢颗粒细胞增殖、卵泡发育。治疗组的AgNOR和PcNA计数明显高于模型组,而与对照组之间无显著差异。结论:补肾中药的这种作用可能是通过调节了下丘脑-垂体-卵巢性腺功能的结果,从而促使卵巢颗粒细胞发育、卵泡成熟。  相似文献   
40.
1. We previously reported that angiotensin II release from the mesenteric arteries of Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) increased in a time-dependent manner as a result of the isolation of the arteries and perfusion. This phenomenon appeared to be due to the withdrawal of circulating angiotensin II (AII). 2. The purpose of the present study was to test the hypothesis that vascular AII generation may be negatively regulated by circulating AII in WKY and SHR, and to clarify the role of this vascular angiotensin II in the sustained hypertension of SHR following nephrectomy. 3. The mesenteric arteries from kidney-intact and nephrectomized WKY and SHR were perfused and the amount of AII released into the perfusate was measured. The effects of the angiotensin converting enzyme inhibitor, captopril, and the effects of supplementation of renal renin and circulating angiotensins to nephrectomized rats, by blood exchange between kidney-intact and nephrectomized rats, on AII release were examined to clarify the pathway of vascular AII generation after nephrectomy. 4. Nephrectomy caused augmentation of vascular AII release both in WKY and SHR in spite of the abolishment of circulating renin. Captopril reduced this enhanced release of AII, but blood exchange did not affect it. There was no significant difference in these responses between WKY and SHR. 5. These results suggest that WKY and SHR have in common a potent pathway for production of vascular AII in response to the withdrawal of circulating AII, although this pathway is not responsible for the sustained hypertension of SHR after nephrectomy. The precise pathophysiological role of this pathway remains to be elucidated.  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