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   108963篇
  免费   6650篇
  国内免费   1316篇
耳鼻咽喉   1692篇
儿科学   3674篇
妇产科学   3141篇
基础医学   12365篇
口腔科学   2860篇
临床医学   8624篇
内科学   25892篇
皮肤病学   2892篇
神经病学   7775篇
特种医学   3275篇
外国民族医学   2篇
外科学   12135篇
综合类   4958篇
现状与发展   1篇
一般理论   31篇
预防医学   11019篇
眼科学   2832篇
药学   7114篇
  2篇
中国医学   1458篇
肿瘤学   5187篇
  2023年   991篇
  2022年   1669篇
  2021年   3238篇
  2020年   1767篇
  2019年   2636篇
  2018年   3613篇
  2017年   2471篇
  2016年   2512篇
  2015年   2654篇
  2014年   3550篇
  2013年   5070篇
  2012年   6627篇
  2011年   7567篇
  2010年   4520篇
  2009年   3933篇
  2008年   5395篇
  2007年   5565篇
  2006年   5092篇
  2005年   5467篇
  2004年   6762篇
  2003年   6165篇
  2002年   5185篇
  2001年   3510篇
  2000年   2775篇
  1999年   2734篇
  1998年   1576篇
  1997年   1362篇
  1996年   919篇
  1995年   796篇
  1994年   783篇
  1993年   1007篇
  1992年   1221篇
  1991年   983篇
  1990年   902篇
  1989年   732篇
  1988年   632篇
  1987年   501篇
  1986年   497篇
  1985年   353篇
  1984年   221篇
  1983年   220篇
  1982年   182篇
  1981年   201篇
  1980年   160篇
  1979年   201篇
  1978年   170篇
  1974年   156篇
  1973年   129篇
  1971年   122篇
  1969年   125篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Two major crotamine isoforms (F22 and F32) were obtained after three chromatographic steps and were assayed in mouse phrenic nerve-diaphragm preparations. F32 and F22 (0.5 microg/ml, n=4) produced a facilitatory effect, which increased isometric twitch-tension by 300 and 230%, respectively, after a 120 min incubation. At a concentration of 0.1 microg/ml, both isoforms increased the twitch-tension by about 160%. However, when the isoforms were co-incubated (final concentration, 0.5 microg/ml) for 30 min prior to testing, they did not cause the facilitation seen with > or =0.1 microg/ml of each isoform alone. Histologically, F32 and F22 at 0.5 and 1 microg/ml were quantitatively alike in inducing tissue myonecrosis. However, a mixture of the two isoforms (final concentration, 0.5 microg/ml) significantly attenuated the damage seen with either toxin alone. Mass spectrometry analysis showed that the isoforms had the same molecular mass (4.8 kDa) and that they existed as monomers with a highly stable structure. These results indicate that F22 and F32 acted on muscle cells of the mouse phrenic-nerve diaphragm preparation through similar mechanisms. Since the isoforms did not produce the expected summation in the increase in muscle twitch-tension, it is possible that they may have different affinities for the sodium channel subunits.  相似文献   
992.
AIM: To study the effect of puerarin (Pue) on Na~+ channel in rat ventricular myocytes. METHODS: Whole-cell patch-clamp technique was applied on isolated cardiomyocytes from rats. RESULTS: Pue inhibited cardiac I_(Na) in a positive rate-dependent and dose-dependent manner, with an IC_(50) of 349 μmol/L. The kinetics of blockage of cardiac sodium channel by Pue resembled the ClassIa/Ic of antiarrhythmic agents. Pue 300 μmol/L did not alter the shape of the I-V curve of I_(Na), but markedly shifted the steady-state inactivation curve of I_(Na) towards more negative potential by 15.9 mV, and postponed the recovery of I_(Na) inactivation state from (21.9±1.6) ms to (54.4±3.4) ms (P<0.01 ). It demonstrated that the steady state of inactivation was affected by Pue significantly. CONCLUSION: Pue protected ventricular myocytes against cardiac damage and arrhythmias by inhibiting recovery from inactivation of cardiac Na~+ channels.  相似文献   
993.
AIM: To explore the possible mechanism of β-amyloid (Aβ)-induced apoptosis in rat cortical neurons and the protective effect of ginsenoside Rg_1. METHODS: AO-EB staining was used to quantify the apoptotic cells. DNA fragmentation was observed by gel electrophoresis. The levels of cyclin-dependent kinases-4 (CDK4) and phosphorylated pRB were detected by Western blot. RT-PCR was used to examine the expression of E2FI mRNA. RESULTS: Treatment with Aβ_(1-40) at the concentration of 20, 40, 80 mg/L for 48 h induced rat cortical neuron poptosis from 12.5%±1.5%(control) to 22.3%±1.4%, 38.8%±1.3%, 36.7%±1.4%, respectively. Pretreatment with Rg_1 at the dose of 0.5, 1, 2, 4, 8, 16 μmol/L for 24 h, then treatment with Aβ_(1-40)40 mg/L for 24 h, the percentage of apoptotic neurons decreased from 38.8%±1.3% to 14.5%±1.3%, 13.3%±1.0%, 11.6%±0.29%, 11.8%±1.0%, 6.2%±0.8%, 5.8%±0.8%, respectively. After treatment with Aβ_(1-40)40 mg/L for 24 h, there were transient increases in CD  相似文献   
994.
This study analysed the effect of low doses ofverapamil added to chronic treatment withangiotensin-converting enzyme (ACE) inhibitors onblood pressure and serum creatinine levels in eightelderly hypertensive patients who had a steadyincrease of serum creatinine while on ACE inhibitors.The study was performed in eight elderly hypertensivesubjects, five men and three women (mean age 70 ±2 years; systolic blood pressure 173 ± 4 mmHg; diastolic blood pressure 99 ± 1 mm Hg) andserum creatinine of 1.60 ± 0.27 mg/dl beforetreatment. During an average of 25 weeks, ACEinhibitors significantly reduced both systolic anddiastolic blood pressures, but serum creatinine levelswere increased over basal levels (0,68 ± 0,20 mg/dl, p < 0.05). During an average of 10 weeks,the addition of verapamil did not decrease bloodpressure further, but serum creatinine levels werereduced to baseline. Our study suggests that theaddition of verapamil to ACE inhibitors can reverseACE-induced increase in creatinine levels in elderlyhypertensive patients in whom this side effect isobserved. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
995.
GM(1,1)灰色模型在尘肺患病人数预测的应用与评价   总被引:1,自引:0,他引:1  
目的 探讨验证灰色模型在尘肺患病人数预测的应用效果。方法 利用该煤矿1996~1986年尘肺患病人数进行建模,并建立了数学模型X(I)=583e^0.038(T-II)-452,作外推预测验证。结果 该灰色预测模型的拟合程度较高,取得了较好的效果。结论 灰色模型可应用于尘肺患病人数的预测。  相似文献   
996.
997.
探讨中药审因论治对乙肝相关性肝癌的治疗作用。应用调补脾肾、搜邪泄浊法 ,对一例乙肝相关性肝癌患者进行单纯中药治疗。结果 :经过 12个月治疗 ,AFP由最高 10 0 0 0 μg/L降至正常 (<2 0 μg/L) ,AFP异质体同步转阴 ,B超、MRI显示肝部实质性肿块消散 ,肝功能好转。提示本治法对肝癌具有较好的治疗作用。  相似文献   
998.
胃粘膜表皮生长因子受体在胃溃疡愈合中的表达   总被引:5,自引:0,他引:5  
目的 探讨人胃溃疡愈合过程中表皮生长因子受体(EGFR)表达的变化及其作用。方法 采用免疫组化方法,对正常胃粘膜(8例)、胃溃疡活动期(GA组10例)、愈合期(GH组10)例)、瘢痕期(GS组10例)组织的EGFR的表达进行定位观察和图像分析。结果GA组胃粘膜GEFR蛋白质和mRNA的表达均较正常时增加,GH及GS组更加明显。结论 在人胃溃疡愈合过程中,胃粘膜EGFR的表达由弱到强。  相似文献   
999.
We report a new case of spermatic cord lymphangioma in a infant 2 years old. The initial diagnosis was funicular hydrocele. The treatment was the local excision of tumor and the diagnostic was histological. Postoperative course was excellent. Must be explored the transillumination of the mass which would have led us to think other the diagnosis different from that of the cord hydrocele before the operation since it would have given negative. During the operation, must the assured that the cystic anomaly is limited to spermatic cord, to evite recurrences in the postoperative course.  相似文献   
1000.
Contribution of a retrospective series of 16 patients with type II absorptive hypercalciuria over a total of 1.041 patients undergoing metabolic study due to relapsing renal lithiasis. Clinical history of lithiasis, biochemistry prior to treatment and instituted therapy were examined in all cases. Stones composition, radiologic appearance of lithiasis and evolution of biochemical parameters after medical treatment with a mixture of phosphates were also studied.  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