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   11053篇
  免费   1057篇
  国内免费   629篇
耳鼻咽喉   25篇
儿科学   45篇
妇产科学   44篇
基础医学   441篇
口腔科学   90篇
临床医学   403篇
内科学   394篇
皮肤病学   166篇
神经病学   196篇
特种医学   209篇
外科学   294篇
综合类   1852篇
预防医学   236篇
眼科学   67篇
药学   6253篇
  13篇
中国医学   1866篇
肿瘤学   145篇
  2024年   29篇
  2023年   100篇
  2022年   195篇
  2021年   288篇
  2020年   295篇
  2019年   221篇
  2018年   249篇
  2017年   339篇
  2016年   400篇
  2015年   443篇
  2014年   880篇
  2013年   832篇
  2012年   931篇
  2011年   988篇
  2010年   729篇
  2009年   573篇
  2008年   656篇
  2007年   698篇
  2006年   594篇
  2005年   508篇
  2004年   460篇
  2003年   392篇
  2002年   281篇
  2001年   232篇
  2000年   211篇
  1999年   159篇
  1998年   105篇
  1997年   134篇
  1996年   99篇
  1995年   87篇
  1994年   63篇
  1993年   56篇
  1992年   48篇
  1991年   36篇
  1990年   37篇
  1989年   25篇
  1988年   37篇
  1987年   35篇
  1986年   38篇
  1985年   33篇
  1984年   28篇
  1983年   29篇
  1982年   22篇
  1981年   23篇
  1980年   27篇
  1979年   17篇
  1978年   11篇
  1977年   12篇
  1976年   15篇
  1973年   13篇
排序方式: 共有10000条查询结果,搜索用时 671 毫秒
51.
宣肺清热颗粒剂稳定性研究   总被引:1,自引:0,他引:1  
目的:研究宣肺清热颗粒剂中橙皮甙热稳定性变化,为该颗粒剂有效期的确定、制剂生产、贮存条什提供实验参考依据。方法:采用加速实验法对橙皮甙热稳定性进行研究,用甲醇超声提取样品,HPLC进行含量测定。根据Arrhenius公式处理数据。结果:Arrhenius公式得室温下的速度常数K298=3.38×10-5/h,得出常温下该颗粒剂以橙皮甙为指标的有效期为3.6年。结论:宣肺清热颗粒剂稳定性好,初步符合中药稳定性要求。  相似文献   
52.
目的 :考察 1 %盐酸丁卡因滴眼液的稳定性 ,确定其有效贮存期。方法 :采用经典恒温法预测其有效期。结果 :经典恒温法[1 ] 预测室温贮存期约为 2 0d ,冰箱贮存期约为 1 1 0d。结论 :该制剂对热不稳定 ,应冷藏。  相似文献   
53.
BACKGROUND: Sevelamer hydrochloride was recently proposed as a phosphate binder to prevent hypercalcaemia in place of calcium alkaline salts in dialysis patients. So far, it has been evaluated only in patients receiving calcitriol, without comparison with CaCO(3) alone, although the latter was found to be as effective as the combination of calcitriol and Al(OH)(3) in suppressing parathyroid hormone (PTH) without inducing hypercalcaemia and to have a better lowering effect on serum phosphate. Moreover, this bile salt binder may decrease serum 25-OH vitamin D. Therefore, we compared for 5 months two strategies for controlling moderate hyperparathyroidism: CaCO(3) alone vs sevelamer in conjunction with measures to increase calcium balance. METHODS: Forty-two patients were randomized: 21 continued their treatment with 4.8 g/day CaCO(3) and 21 were switched to sevelamer (initial dose: 2.4 g/day, increased to 4.4 g/day). Each month, when serum-corrected calcium decreased below 2.30 mmol/l, dialysate calcium was increased or alphacalcidol was given at each dialysis session, according to serum PO(4) levels. The following parameters were monitored: serum Ca, PO(4), bicarbonate and protein, weekly; and serum PTH, 25-OH vitamin D and total, LDL and HDL cholesterol monthly. RESULTS: Except for higher serum phosphate at month 1, lower serum bicarbonate at month 2 and lower LDL cholesterol at month 5 in the sevelamer group, no difference was found between the two groups. Compared with baseline levels, PTH increased and 25-OH vitamin D decreased significantly in both groups, these two parameters being inversely correlated. CONCLUSIONS: Given comparable control of plasma calcium, phosphate and 25-OH vitamin D, PTH control is comparable in both strategies. Sevelamer does not induce greater vitamin D depletion than CaCO(3). The transient decrease of serum bicarbonate after discontinuation of CaCO(3) in the sevelamer group suggests a less optimal prevention of acidosis. The sevelamer-induced decrease in LDL cholesterol gives this drug a potential advantage in cardiovascular prevention.  相似文献   
54.
目的研究抗胆碱新药盐酸三环哌酯(TCPN)在小鼠体内的药代动力学及组织分布。方法药代动力学采用放射受体分析法研究,组织中的分布用放射同位素分析法研究。结果小鼠scTCPN后,血液中药物浓度的经时过程符合一级吸收二室模型(T1/2β为2.28h,Tmax为0.125h,Cmax为3.44μg·L-1,Cl为23.0L·kg-1·h-1)。小鼠sc[3H]-TCPN后,分布高峰放射性依次为肾>肝>脑>颌下腺>肠1998-04-03收稿,1998-07-26修回*国家自然科学基金资助课题,No39130090-2作者简介:葛召恒,男,32岁,硕士,助理研究员;阮金秀,男,62岁,研究员,博士生导师,中国毒理学会副理事长,中国药理学会药物代谢专业委员会主任委员>心>肌肉,唯有脑组织的放射性以较高的水平维持较长的时间。预先给小鼠sc不同剂量的QNB,可不同程度地降低脑中放射性的分布。结论TCPN从血中的消除较快,但在脑组织分布时间长,这与药物与脑中M受体的特异性结合有关。  相似文献   
55.
盐酸氯胺酮-β-环糊精包合物的研究   总被引:4,自引:1,他引:3  
颜耀东  王虹 《中国药房》1998,9(6):255-256
采用正交设计法对饱和水溶液法制备盐酸氯胺酮-β-环糊精包合物的温度、时间及投料比进行选优,显微观察包合物形态,UV和X-射线衍射法测试包合物晶形变化,品尝包合物味觉效果,并测定其稳定性及溶出度。结果表明,按1:2主客克分子比,于25℃电动搅拌3h,制备包合物的包合率和收率较高,包合物已形成一种新物相,具有稳定性高,无苦味及缓释性能。  相似文献   
56.
A case of small round and spindle cell sarcoma with neuronal differentiation and oncocyte-like features is presented. The tumor was encountered in a 32 year old Japanese woman with an initial presentation of palpable tumor in the left lateral region of the thorax. The resected tumor was a partially well encapsulated whitish medullary one and consisted of small round and spindle tumor cells, together with so-called rhabdoid cells in the small round cell area. Although pseudorosettes were often observed, true rosette formation could not be detected anywhere. Ultrastructurally, despite a histologic variety of tumor cells, most tumor cells possessed numerous mitochondria, some of which occasionally contained abnormal filamentous or crystalloid structures. Various amounts of microfilaments were present in most tumor cells and microtubules were present in a few. A minority of small round cells possessed a small number of neurosecretory granules, especially in short cytoplasmic processes. A positive immunoreaction for neuron specific enolase was found by immunohistochemical examination in several small round tumor cells and for neurofilaments in lesser numbers. Despite the lack of S-100 protein, MB2 was detected in both small round and spindle cells. On the basis of these findings, the tumor of the present case corresponds to malignant peripheral nerve sheath tumor with neuronal differentiation and oncocytic features.  相似文献   
57.
川芎嗪诱导大鼠骨髓间质干细胞分化为神经元样细胞的研究   总被引:26,自引:0,他引:26  
撒亚莲  李海标 《解剖学报》2003,34(5):514-517
目的用川芎嗪(ligustrazin hydrochloride)在体外定向诱导SD青年鼠骨髓间质干细胞(mesenchymal stem cells,rMSCs)分化为神经元样细胞。方法用低糖DMEM冲洗骨髓腔,收集骨髓细胞悬液,接种在塑料培养瓶中。经体外扩增、纯化,选用第5代后的骨髓间质干细胞进行诱导分化。用10μg/LbFcF预诱导24h,更换成含川芎嗪的无血清培养基DMEM诱导间质干细胞分化为神经元样细胞。用免疫组织化学SABC法鉴定神经丝蛋白(NF—M)、神经元特异性烯醇化酶(NSE)、巢蛋白(nestin)、微管联合蛋白-2(MAP-2)、生长相关蛋白-43(GAP-43)、胶质纤维酸性蛋白(GFAP)的表达。结果第5代间质干细胞形态达到均一,呈梭形。用川芎嗪诱导15min到3h,间质干细胞胞体逐渐增大,并伸出细长突起形似神经元样细胞。免疫组织化学显示NF-M、NSE、nestin、MAP-2和GAP-43表达阳性,而GFAP阴性。对照组上述染色均为阴性。结论川芎嗪可诱导骨髓间质干细胞分化为神经元样细胞。  相似文献   
58.
制备盐酸恩丹西酮缓释片并对影响释药的因素进行考察。以羟丙甲纤维素(HPMC)为骨架材料制备了盐酸恩丹西酮缓释片,通过正交设计试验优选最佳处方和工艺。对影响释药的因素,如HPMC的黏度和用量、填充剂的种类、制片工艺、润湿剂及释放介质pH等进行了考察。盐酸恩丹西酮缓释片体外释药符合Higuchi方程,HPMC的黏度、填充剂的种类及测定释放度的转速对该缓释片的释药几乎无影响,而制片工艺、润湿剂及释放介质pH值对缓释片释药影响较大。盐酸恩丹西酮缓释片在体外12h缓释效果较好。  相似文献   
59.
建立毛细管电泳分离分析多巴胺和 5一羟色胺的方法。采用自由区带电泳法 (CZE) ,4 0mmol/L硼砂缓冲液 2 0PSI气压进样 5s ,定电流 75 μA分离 10min ,二极管阵列PDA检测器检测 ,应用 2 0 0nm检测波长 ,结果显示两种物质完全分离。  相似文献   
60.
A melanotic paraganglioma occurred in a 57-year-old woman, located in the left paravertebral space of the upper mediastinum. It was totally resected. During a 5 year follow up period neither tumour reccurrence nor metastasis were observed. Histological examination of the tumour revealed a paraganglioma with monomorphous chief cell like elements which were arranged in a zellballen pattern. Immunohistochemical results also were in accordance with the diagnosis since neuron-specific enolase, chromogranin and synaptophysin were found in tumour cells whereas keratin was not. Additionally, neurosecretory granules were found in tumour cells during electron microscopy. A peculiar feature of the tumour was its strong pigmentation due to melanin located within the tumour cells and tumour associated melanophages. The simultaneous expression of functional properties of two different neural crest derived cells in one tumour stresses the close relationship between all neural crest elements and is in accordance with the observation of other melanotic, non-melanomatous tumours.Dedicated to Prof. Dr. Dr. mult. h.c. W. Doerr on the occasion of his 80th birthday  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