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   180378篇
  免费   17474篇
  国内免费   11640篇
耳鼻咽喉   1627篇
儿科学   1902篇
妇产科学   2427篇
基础医学   21807篇
口腔科学   3256篇
临床医学   23713篇
内科学   26145篇
皮肤病学   2205篇
神经病学   9429篇
特种医学   6434篇
外国民族医学   97篇
外科学   18335篇
综合类   29537篇
现状与发展   39篇
一般理论   22篇
预防医学   11889篇
眼科学   4745篇
药学   19589篇
  186篇
中国医学   10914篇
肿瘤学   15194篇
  2024年   611篇
  2023年   2665篇
  2022年   6763篇
  2021年   9695篇
  2020年   7265篇
  2019年   6257篇
  2018年   6602篇
  2017年   6063篇
  2016年   5649篇
  2015年   8698篇
  2014年   10562篇
  2013年   9758篇
  2012年   14249篇
  2011年   15399篇
  2010年   9816篇
  2009年   7556篇
  2008年   10043篇
  2007年   9509篇
  2006年   9124篇
  2005年   8865篇
  2004年   5679篇
  2003年   5143篇
  2002年   4251篇
  2001年   3595篇
  2000年   3792篇
  1999年   3849篇
  1998年   2280篇
  1997年   2334篇
  1996年   1782篇
  1995年   1734篇
  1994年   1514篇
  1993年   906篇
  1992年   1279篇
  1991年   1119篇
  1990年   898篇
  1989年   843篇
  1988年   762篇
  1987年   604篇
  1986年   455篇
  1985年   397篇
  1984年   190篇
  1983年   162篇
  1982年   93篇
  1981年   123篇
  1980年   79篇
  1979年   108篇
  1978年   52篇
  1977年   51篇
  1976年   42篇
  1974年   44篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
901.
For a period of six months, we collected 12 cases of nocturnal asthmatics (7 males, 5 females); their ages ranged from 20 to 66 (the average age is 49). We found that administration of Uniphyllin (10 mg/kg) once a day at 6 PM could maintain the blood level of theophylline within therapeutic range at least 12 to 24 hrs. The peak expiratory flow rate of the 6 cases we collected, were significantly improved. The result of pharmokinetic parameters: 1) The average of a single dose (12 cases) is AUC (ug. hr/ml) 275.1 +/- 62. k; Kel (hr-1) 0.068 +/- 0.019; Ka (hr-1) 0.33 +/- 0.07); Tmax (hr) 6.3 +/- 1.4; T 1/2 (hr) 11.2 +/- 4.4; Clearance/F (ml/kg/hr) 37.9 +/- 9.0.2). The average of steady state (12 cases) is Css (mg/L) 5. 7 +/- 2.6; Cmax-Cmin (mg/L) 10.09 +/- 1.46.3). The average of relative bioavailability (3 cases) is 82%, 83%, 102%. However, the extent of absorption data is available for only 3 subjects. There are too few subjects to draw any meaningful conclusions about this relative bioavailability. Four cases show slight symptoms, including 1 case of dizziness, 2 cases of nausea, and 1 case gaseousness. It is suggested that the drug be administered at about 6-8 PM to coincide peak levels in the early morning in nocturnal asthmatics.  相似文献   
902.
Rat spinal cord contains the opioid peptide including [Met5]enkephalin-Arg6-Gly7-Leu8 (YGGFMRGL) and a higher molecular weight (HMW) immunoreactive peptide which is an N-terminal extended molecular form of YGGFMRGL. Since a high proportion of tissue immunoreactivity resides in the HMW component we have determined whether this form is released during perfusion of the spinal cord subarachnoid space in vivo while (1) electrically stimulating the sciatic nerves bilaterally or (2) superfusing with substance P. We have found that YGGFMRGL and the HMW immunoreactivity are released by both types of stimuli. The HMW material appeared to be the more stable of the two species of immunoreactivity; its presence in the superfusate was more consistently observed than that of YGGFMRGL itself. Injection of YGGFMRGL into the spinal subarachnoid space in chronically catheterized rats produced a suppression of the tail-flick response. This effect of YGGFMRGL was reversed by naloxone suggesting an action mediated by spinal opiate receptors. These data suggest that YGGFMRGL plays an integral role in the neurotransmission process between spinal neurons storing enkephalin and other neurons. The possibility that enkephalin-mediated neurotransmission includes multiple chemical signals can be entertained.  相似文献   
903.
In the present paper we report the mitogenic effect of the sheep anti-porcine lymphocyte E-receptor antiserum IgG(APERIgG) on porcine peripheral T-lymphocytes in vitro. The effect was apparently dose-dependent and not seen in the B-lymphocyte cultures. Kinetic study showed that the maximal 3H-thymidine incorporation, similar to that induced by Con A, occurred on the third day of incubation. Neither F(ab')2 nor Fab fragment of APERIgG was able to induce cell proliferation, indicating that the integrity of IgG molecule was essential for cell response. It was very interesting to note that though there is cross antigenicity between porcine and human E-receptors, no similar effect could be produced by APERIgG in human peripheral lymphocyte cultures under the same experimental conditions, suggesting the existence of minor difference in structure between the porcine and human E-receptors.  相似文献   
904.
目的评价米非司酮用于保守治疗异位妊娠的疗效。方法所选病例均住院治疗,予口服米非司酮50mg,每天两次,连服6天,定期复查B超和测定血p—HCG水平以观察疗效。结果68例异位妊娠患者的治疗,治愈46例,治愈率67.7%。结论米非司酮保守治疗异位妊娠疗效确切,副作用小。  相似文献   
905.
目的探讨原发性甲状腺机能亢进症的手术探查技巧和经验教训。方法对50例原发性甲状腺机能亢进症患者临床资料进行回顾性总结分析。结果48例患者手术治疗,术后38例诊断为甲状旁腺瘤,6例为甲状旁腺增生,4例为甲状旁腺癌。48例中44例第一次手术探查成功(占88%),2例行2次手术,2例行3次手术。46例术后痊愈,2例并发多处肋骨骨折发生呼吸衰竭而死亡。结论确诊为原发性甲状腺机能亢进症伴有临床征象者均应手术治疗。术前病灶定位明确者手术较容易,定位不明确者应在“热区内”重点探查。  相似文献   
906.
The binding of radiolabelled lipoproteins, iodine-123-labelled low-density. lipoprotein (LDL) and indium-111-labelled LDL, to peripheral blood mononuclear cells (MNCs) was compared in normolipaemic subjects and in patients with heterozygous familial hypercholesterolaemia (FH). 123I-LDL and 111In-LDL binding to MNCs exhibited high-affinity, highly specific, time- and temperature-dependent binding reaching saturation at concentrations above 50 nM. The number of LDL binding sites (Bmax) was significantly (P<0.01) lower in FH patients (P<0.001; 123I-LDL: Bmax 279±44 ng protein/108MNCs; 111In-LDL: Bmax 309±43 ng protein/108MNCs) as compared with controls (123I-LDL: Bmax 2874±246 ng protein/108 MNCs; 111In-LDL: Bmax 3145±339 ng protein/108 MNCs). The corresponding dissociation constants (K d) were 16±8 nM for 123I-LDL and 12±6 nM for 123In-LDL in healthy volunteers (123In-LDL vs 111In-LDL, P<0.05). In FH patients, the K d values were 20±8 nM for 123I-LDL and 16±6 nM for 123In-LDL (P<0.05 vs controls for both 123I-LDL and 111In-LDL). 111In-LDL binding to MNCs was inhibited (IC50) by 30±8 nM in healthy controls and 38±12 nM in FH patients (P<0.05). 123In-LDL binding to MNCs was inhibited (IC50) by 34±8 nM in healthy controls and 46±10 nM in FH patients (P<0.05). Taken together, these results suggest a reduced number of LDL receptors expressed on MNCs from FH patients. We conclude that 111In-LDL and 123I-LDL are equally well suited as a probe of receptor-mediated binding and uptake of LDL.  相似文献   
907.
应用体视学方法对卵巢浆液性肿瘤进行研究,从定量的角度对卵巢良性、交界性及恶性肿瘤的五项指标进行比较,包括(1)细胞核长短轴之比;(2)结缔组织间质与上皮细胞体积密度之比;(3)细胞核与细胞浆体积密度之比(核浆比);(4)细胞核平均直径;(5)乳头的上皮厚度。结果表明恶性肿瘤核浆体积密度比明显高于交界性及良性肿瘤(p<0.01);恶性肿瘤结缔组织间质与上皮细胞体积密度之比明显小于交界性及良性肿瘤(P<0.01)。  相似文献   
908.
L C Mu  S L Yang 《The Laryngoscope》1991,101(8):849-854
The activity of the posterior cricoarytenoid muscle during respiration has been well investigated electromyographically. Its activity during phonation, however, has not been studied systematically. We, therefore, focused our attention on the phonatory activity of the posterior cricoarytenoid muscle to confirm whether it also contracts during phonation, as has been reported by some researchers. In our series of 12 adult dogs, the posterior cricoarytenoid was active in 11 dogs and inactive in one dog during phonation. Our present study also showed that the posterior cricoarytenoid activity was stronger for phonation than for inspiration in 6, stronger for inspiration than for phonation in 3, and the same for phonation and inspiration in 2 dogs. The results obtained from the present electromyographic evaluation demonstrated that the posterior cricoarytenoid is activated during phonation. The authors believe that the posterior cricoarytenoid muscle has phonatory function and that the phonatory effect of this muscle on the vocal cord may play an important role in precise glottis control.  相似文献   
909.
目的调查HIV/AIDS病人结核菌素(PPD)试验反应状况及与免疫系统受损程度的联系,并探讨其预防和治疗结核病的意义。方法采用前瞻性病例对照研究方法,对40例HIV(+)者和202例HIV(-)者做结核菌素试验,并对HIV(十)者做CD4、CD8细胞计数测定,对HIV(+)分组服药,观察胸部病变情况。结果HIV(+)与HIV(-)者PPD阳性率分别为12.5%、28.2%(P<0.05)。当CD4细胞计数下降时,PPD反应减弱。CD4<200个/mm3时PPD均无反应(0×0).病例服药组经化学药物预防治疗后其肺部病变异常率小于病例对照组。结论HIV(+)者中PPD阳性率显著低于HIV(-)者。CD4细胞数下降可能是艾滋病并发结核的主要原因.对HIV/AIDS患者使用化学药物预防和治疗结核是有效的。  相似文献   
910.
脑脓肿的诊断及治疗   总被引:1,自引:0,他引:1  
目的:进一步探讨脑脓肿发病情况,影像学表现,选择最佳治疗方法,提高治疗效果。方法:回顾分析147裂离脓肿的发病,病因,影像学表现,治疗方法及死亡率下降因素,结果:脑脓肿发病年龄较年青,血源性及隐源性脑脓肿发病率升高,CT结合MRI可明确诊断,选择最佳手术方法。CT应用后死亡率由23.8%下降到7.5%,结论:CT为脑脓肿最主要的诊断方法,CT定位下穿刺排脓可治愈大部分脑脓肿。  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