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   15332篇
  免费   711篇
  国内免费   674篇
耳鼻咽喉   66篇
儿科学   274篇
妇产科学   89篇
基础医学   1989篇
口腔科学   68篇
临床医学   871篇
内科学   1609篇
皮肤病学   145篇
神经病学   762篇
特种医学   397篇
外科学   911篇
综合类   1400篇
预防医学   850篇
眼科学   84篇
药学   5028篇
  2篇
中国医学   1672篇
肿瘤学   500篇
  2023年   123篇
  2022年   262篇
  2021年   285篇
  2020年   244篇
  2019年   211篇
  2018年   228篇
  2017年   257篇
  2016年   279篇
  2015年   301篇
  2014年   630篇
  2013年   705篇
  2012年   637篇
  2011年   698篇
  2010年   562篇
  2009年   466篇
  2008年   488篇
  2007年   516篇
  2006年   483篇
  2005年   963篇
  2004年   996篇
  2003年   671篇
  2002年   315篇
  2001年   312篇
  2000年   250篇
  1999年   264篇
  1998年   225篇
  1997年   238篇
  1996年   289篇
  1995年   384篇
  1994年   374篇
  1993年   376篇
  1992年   329篇
  1991年   316篇
  1990年   240篇
  1989年   262篇
  1988年   246篇
  1987年   216篇
  1986年   204篇
  1985年   208篇
  1984年   180篇
  1982年   172篇
  1981年   153篇
  1980年   139篇
  1979年   129篇
  1978年   122篇
  1977年   107篇
  1976年   124篇
  1974年   76篇
  1973年   89篇
  1972年   76篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
用紫外分光度法直接溯定复方卡托普利片中氢氯噻嗪的含量及均匀度。测定波长为272±1nm,平均回收率100.2%,变异系数0.3%,吸收度与氢氯噻嗪的浓度在1~10μg/ml 范围内具有线性关系。  相似文献   
32.
作者对结节性甲状腺肿及其非典型结节与甲状腺癌细胞核直径、面积及 DNA 含量检测,发现核直径与面积的(?)和 S 为甲状腺癌组>非典型结节组>对照组(P<0.01);随着细胞增生异型程度的加重,核直径、面积及离散程度随之增加、DNA 含量也显著增加,显示Ⅲ级 DNA 含量细胞出现频率越高恶性的可能性就越大;同时发现各组细胞核不同 DNA 含量的核直径、面积均明显增加,与对照组相比差异生非常显著(P<0.01)。  相似文献   
33.
[目的 ]研究芪月降脂片中黄芪甲苷的含量测定方法 .[方法 ]用甲醇提取、水饱和正丁醇萃取、大孔吸附树脂处理供试品后 ,以双波长薄层扫描法测定黄芪甲苷的含量 .[结果 ]黄芪甲苷的平均回收率为 10 4 18% ,RSD为 3 2 5% .[结论 ]双波长薄层扫描法较为简便、经济且重现性较好 ,可用于制剂中黄芪甲苷的质量控制  相似文献   
34.
Summary The present study was designed to clarify whether or not a difference between arterial and venous lactate (content/u50422055h6rl568/xxlarge916.gif" alt="Delta" align="BASELINE" BORDER="0">lactate) levels is useful for evaluation of mitochondrial function in ischemia-reperfused myocardium. In the first experiment, 12 dogs were divided into 2 groups: 10-min occlusion of the left anterior descending coronary artery (LAD) followed by 10-min reperfusion, or 30-min occlusion followed by 40-min reperfusion, were performed. The lactate levels in the femoral artery and the great cardiac vein were measured enzymatically. content/u50422055h6rl568/xxlarge916.gif" alt="Delta" align="BASELINE" BORDER="0">Lactate was reversed immediately after occlusion. Ten min and 20 min were required for the recovery of content/u50422055h6rl568/xxlarge916.gif" alt="Delta" align="BASELINE" BORDER="0">lactate in the 10-min-occlusion with 10-min-reperfusion, and 30-min-occlusion with 40-min-reperfusion groups, respectively. In the second experiment, 36 dogs were divided into 6 groups: 10-min occlusion of LAD; 10-min occlusion with 10-min reperfusion; 30-min occlusion; and 30-min occlusion with 10-, 20-, or 40-min reperfusion were performed. Mitochondria from normal and occluded or reperfused areas were prepared, and the respiratory function of the mitochondria was measured polarographically. No significant decreases in the mitochondrial function were observed in the 10-min-occlusion, and 10-min-occlusion with 10-min-reperfusion groups. On the other hand, respiratory function of mitochondria was impaired by 30-min occlusion and was not improved by 10- or 20-min reperfusion. Significant recovery in the mitochondrial function was observed after 40-min reperfusion. That is, differing recovery time courses between content/u50422055h6rl568/xxlarge916.gif" alt="Delta" align="BASELINE" BORDER="0">lactate and the mitochondrial function were observed.  相似文献   
35.
Summary In a previous study we observed that calcitonin increases content/m05j170173261525/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-endorphin, ACTH, and cortisol secretion. We assumed that calcitonin might have a modulatory role on the pituitary function. The present study was initiated to clarify whether this effect is due to a direct pituitary stimulation or to an indirect stimulation through CRF (corticotropin releasing factor).Fourteen healthy subjects, aged 30–60 years were investigated. All the subjects received 100IU Salmon calcitonin Sandoz i.v. at 8a.m. (time 0). Plasma content/m05j170173261525/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-endorphin, ACTH and cortisol were estimated every 30min from – 30 to 120 min by specific radioimmunoassay. The same parameters were estimated a second time, at the same intervals, when cyproheptadine 8 mg (7 subjects) and 40 mg propranolol (7 subjects) were given per os at – 30 min and calcitonin i.v. at time 0. content/m05j170173261525/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-endorphin, ACTH and cortisol levels (Mean ±SEM) rose significantly after calcitonin (peak value at 30–90 min) from 5.2 ±0.7 to 15.1±2.6 pmol/l; from 43.0±2.7 to 70.7±4.1 pg/ml and from 10.6±1.5 to 19.6 ±2.1 content/m05j170173261525/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">g/100 ml respectively (p< 0.0001 by analysis of variance and covariance and repeated measures). Propranolol 40 mg (per os) administered at time – 30 did not alter the response of content/m05j170173261525/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-endorphin, ACTH and cortisol to calcitonin (infused at time 0).Cyproheptadine, the antiserotonergic substance that inhibits the synthesis and release of CRF completely inhibited the stimulatory effect of calcitonin.We conclude that probably calcitonin has a modulatory role on the hypothalamo-pituitary adrenal axis and that it acts at the hypothalamic level probably by stimulating CRF secretion.  相似文献   
36.
Summary The size of the neuronal and non-neuronal histamine pools in the brain of three different strains of rats was measured by assuming that the content/l072557712553u57/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-fluoromethylhistidine-induced maximal decrement of histamine represents the size of the neuronal pool. Although the total histamine levels in the brain showed a considerable interstrain variation, no significant interstrain difference was observed in the neuronal histamine level. These results suggest that the size of the neuronal histamine pool in the brain is relatively stable, whereas the size of the non-neuronal histamine pool is variable.  相似文献   
37.
Summary A behavioural test involving potentiation of the effects of an acute injection of content/x7271302rh6v77j5/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-phenylethylamine (10 mg kg–1 i.p.) was used to assess the time-course of type-B MAO inhibition after administration of (–)deprenyl (5 mg kg–1 i.p.) and of MD 240928 (20 mg kg–1 i.p.) respectively. Potentiation of the effects of content/x7271302rh6v77j5/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-phenylethylamine was observed 1 h after injection of (–)deprenyl or MD 240928. This effect was still evident 120 h after administration of (–)deprenyl but not 24 h after administration of MD 240928. Comparisons of ex vivo estimates of MAO activity yielded a corresponding time-course for the recovery of this enzyme. The extent of MAO inhibition required for potentiation of the effects of content/x7271302rh6v77j5/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-phenylethylamine was inferred from a comparison of the behavioural test results and the ex vivo MAO activity observed after (–)deprenyl administration. These comparisons indicate a significant underestimation of MD 240928-induced MAO inhibition using ex vivo measures. This underestimation is interpreted as evidence fordilution effects in the ex vivo assay of MAO inhibition. The potentiation of effects of content/x7271302rh6v77j5/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-phenylethylamine under the present conditions is proposed as a useful and simple test for effects of reversible type-B MAO inhibitors.  相似文献   
38.
Summary Impairment of skeletal muscle function is the common feature of distinct clinical forms of glycogenosis type II. In the present study, muscle cultures from different patients were used to investigate the cause of clinical heterogeneity and the feasibility of enzyme replacement therapy. The activity of acid content/u0864817np01rk54/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-glucosidase appears to be the primary factor in determining the extent of lysosomal glycogen storage in muscle, and thereby the clinical severity of the disease. Neutral content/u0864817np01rk54/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-glucosidases do not seem influencial. Correction of the enzymatic defect was achieved in skeletal muscle cultures from patients by administration of a content/u0864817np01rk54/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">high-uptakecontent/u0864817np01rk54/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> form of acid content/u0864817np01rk54/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-glucosidase, purified from human urine. The enzyme reaches the lysosomes, including the glycogen storage vacuoles, and the lysosomal glycogen content is reduced to control level. In normal muscle cells 20% of the total cellular glycogen pool is segregated in lysosomal compartments. This percentage is higher than in fibroblasts, which may partly explain why muscles are more prone to store glycogen. The relevance of this study for enzyme therapy is discussed.  相似文献   
39.
Adult-onset rod disease with abundant intranuclear rods   总被引:2,自引:0,他引:2  
Summary The third case of adult-onset rod disease (nemaline myopathy) with abundant myofibrillar as well as intranuclear rods is described. The 61-year-old woman suffered from progressive weakness of proximal extremities and of the neck, mimicking polymyositis. Muscle biopsy revealed a striking myopathic pattern, with intranuclear rods occurring in 31% of the fibres. On light and electron microscopy and by immunohistochemical study, the rods differed from myofibrillar rods. The absence of content/x83816k16684k231/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-actinin in intranuclear rods suggests an enhanced readiness of actin filaments to bind to diverse proteins, instead of overproduction of content/x83816k16684k231/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-actinin as the pathogenetic basis of the rod formation.  相似文献   
40.
Summary In Denmark it is legal to grow opium poppies for the production of poppy seeds and until 1986 for decoration purposes, too. Danish poppy capsules contain 0.3–5 mg morphine per capsule and the content of morphine in opium exuded from the capsules may amount to 24%. This has resulted in misuse as both fresh and dried poppy capsules have been used for the production of content/x3253h740tg5801p/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">opium teacontent/x3253h740tg5801p/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0">. During the period 1982–1985, seven casualties occurred among drug addicts in Denmark which were solely or partly caused by these opium poppies.  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