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   3587篇
  免费   441篇
  国内免费   224篇
耳鼻咽喉   10篇
儿科学   20篇
妇产科学   17篇
基础医学   268篇
口腔科学   18篇
临床医学   110篇
内科学   198篇
皮肤病学   44篇
神经病学   55篇
特种医学   43篇
外科学   98篇
综合类   551篇
预防医学   108篇
眼科学   24篇
药学   1591篇
  2篇
中国医学   1073篇
肿瘤学   22篇
  2024年   24篇
  2023年   59篇
  2022年   103篇
  2021年   135篇
  2020年   143篇
  2019年   116篇
  2018年   101篇
  2017年   148篇
  2016年   182篇
  2015年   188篇
  2014年   352篇
  2013年   274篇
  2012年   285篇
  2011年   297篇
  2010年   198篇
  2009年   186篇
  2008年   170篇
  2007年   202篇
  2006年   160篇
  2005年   145篇
  2004年   113篇
  2003年   98篇
  2002年   70篇
  2001年   60篇
  2000年   37篇
  1999年   34篇
  1998年   28篇
  1997年   30篇
  1996年   23篇
  1995年   19篇
  1994年   18篇
  1993年   19篇
  1992年   14篇
  1991年   15篇
  1990年   15篇
  1989年   10篇
  1988年   20篇
  1987年   12篇
  1986年   19篇
  1985年   18篇
  1984年   12篇
  1983年   14篇
  1982年   8篇
  1981年   16篇
  1980年   15篇
  1979年   6篇
  1978年   6篇
  1977年   8篇
  1976年   9篇
  1970年   5篇
排序方式: 共有4252条查询结果,搜索用时 31 毫秒
31.
Summary Partially purified chromaffin granules (granular fraction), crude mitochondria (mitochondrial fraction) and a microsomal fraction were prepared from bovine adrenals by differential centrifugation and characterized by their catecholamine content, succinate dehydrogenase and glucose-6-phosphatase activity. During isotonic incubation with 0.1 mM 45Ca2+ all fractions showed an uptake of 45Ca2+, which was stimulated by ATP. In addition, after incubation the granular fraction was further fractionated by sucrose density gradient centrifugation (2.0–1.3 M sucrose; 170,000g·60 min). In some of these experiments the granular fraction was incubated simultaneously with 45Ca2+ and [3H](-)noradrenaline to compare the uptake of both. The rate of uptake of 45Ca2+ into the 2.0 M sucrose fraction (characterized by the highest catecholamine content and the lowest succinate dehydrogenase activity) was doubled by ATP. The ATP-stimulated uptake of 45Ca2+ into the 2.0 M sucrose fraction of chromaffin granules was inhibited by N-ethylmaleimide (NEM) (0.1 mM), 2,4-dinitrophenol (DNP) (0.1 mM), azide (1 mM), carbonyl cyanide mchlorophenylhydrazone (CCCP) (20M), atractyloside (50 M), ruthenium red (40 M) and amobarbital (1 mM). This inhibition pattern was different from that of the ATP-stimulated uptake of 45Ca2+ into the microsomal fraction, but it was similar to that of the ATP-stimulated uptake of 45Ca2+ into the mitochondrial fraction. However, the following differences are incompatible with the view that a mitochondrial contamination, with a highly active uptake, is responsible for the ATP-stimulated uptake of 45Ca2+ into the 2.0 M sucrose fraction of chromaffin granules: a) The uptake of 45Ca2+ into the mitochondrial fraction was insensitive to 1 mM amobarbital, whereas this agent inhibited the uptake of 45Ca2+ into the 2.0 M sucrose fraction of chromaffin granules. b) Replacement of ATP by succinate stimulated the uptake of 45Ca2+ into the mitochondrial fraction only. c) The dependence of the ATP-stimulated uptake of 45Ca2+ on the concentration of ATP (0.1–5 mM) was determined: while uptake into the 2.0 M sucrose fraction of chromaffin granules exhibited saturation kinetics, that into the mitochondrial fraction was linearly related to the concentration of ATP. Interestingly, uptake of 45Ca2+ into those fractions of chromaffin granules that are known to be contaminated with mitochondria (1.6 M sucrose fraction) exhibited bot a saturable and a nonsaturable component. d) The uptake of 45Ca2+ into the mitochondrial fraction was more sensitive to 0.1 mM DNP than the uptake of 45Ca2+ into the 2.0 M sucrose fraction of chromaffin granules.The comparison of the ATP-stimulated uptake of 45Ca2+ with that of [3H](-)noradrenaline into the 2.0 M sucrose fraction of chromaffin granules revealed that amobarbital, N,N-dicyclohexylcarbodiimide (DCCD), DNP and increasing concentrations of ATP had the same influence on both uptake processes. From our results we conclude that an inherent, ATP-stimulated uptake of 45Ca2+ exists in chromaffin granules. The effects of agents on the uptake of 45Ca2+ and/or [3H](-)noradrenaline into chromaffin granules are discussed with regard to the granular uptake mechanisms.This work was supported by the Deutsche ForschungsgemeinschaftSome results were reported at the 18th Spring Meeting 1977 of the Deutsche Pharmakologische Gesellschaft (Burger and Häusler 1977)  相似文献   
32.
Primary infiltrating signet ring carcinoma of the eyelids   总被引:1,自引:0,他引:1  
A 61-year old man presented with a five-year history of a swelling initially developing in his right lower lid that progressed to involve the lateral canthal skin and eventually the upper lid and anterior orbit. He was discovered to have an infiltrating, poorly differentiated, mucin-producing carcinoma. Systemic work-up failed to disclose a visceral malignancy, and it was concluded that his tumor was primary in the lids, arising from an adnexal sweat gland. Three other reports in the literature also share almost identical clinical and pathologic features, in that all of the earlier reports dealt with middle-aged or elderly men who had diffusely indurated lids. Histopathologically, the tumor cells grow diffusely in a sclerotic stroma, and resemble the "histiocytoid" variant of metastatic breast carcinoma to the lids in women. Ultrastructural studies in our case point toward an apocrine origin, although earlier authors have favored an eccrine origin. Despite its indolent clinical course, the tumor is capable of producing regional and distant metastases on long-term follow-up. Complete local excision, possibly necessitating radical surgery, is probably the preferred method of treatment, but local radiotherapy may have a beneficial effect in retarding spread of the disease.  相似文献   
33.
The Merkel cell is a distinctive nondendritic, nonkeratinocytic, epithelial clear cell believed to migrate from the neural crest to the epidermis and dermis, which is usually located in or near the basal layer of the epidermis and associated with nerve terminations. Merkel first described these cells in 1875 as "Tastzellen" occurring in the snout of a mole. They are believed to function as slowly adapting mechanoreceptors that mediate the sense of touch. Tumors arising from Merkel cells have been reported to occur on the head and neck area, the trunk, arms, and legs, and resemble a primary cutaneous lymphoma or cutaneous metastasis of a lymphoma or a carcinoma. Electron microscopy, to locate the characteristic membrane-bound, dense core neurosecretory granules, is needed for accurate diagnosis. These tumors must be treated aggressively to minimize the chance of local recurrence and nodal or visceral metastases. The authors present a case of Merkel cell tumor occurring on the eyelid. The clinical history, light and electron microscopic findings are shown.  相似文献   
34.
板蓝根醇沉物的药理作用   总被引:5,自引:0,他引:5  
目的:观察板蓝根醇沉物与板蓝根颗粒剂的差异。方法:对比研究板蓝根醇沉物与板蓝根颗粒剂前浸膏的药理作用。结果:板蓝根醇沉物的热解、抗炎及抗茵作用与同剂量板蓝根颗粒剂前浸膏相同,其靛蓝含量高于板蓝根颗粒剂前浸膏。结论:板蓝根醇沉物有明显的解热、抗炎作用,板蓝根制剂传统制备工艺有待改进。  相似文献   
35.
尿石通颗粒中总黄酮的含量测定   总被引:2,自引:0,他引:2  
目的:测定尿石通颗粒中总黄酮的含量。方法:用70%乙醇提取并制成供试品,采用分光光度法测定。结果:平均回收率为98.28%,RSD=2.13%。3批尿石通颗粒样品中总黄酮的含量分别为1.448,1.403,1.427 mg·g~(-1)。结论:本方法简便、准确、灵敏度高,可作为该制剂的质量控制方法。  相似文献   
36.
金叶败毒颗粒对孕鼠免疫和生殖功能影响的研究   总被引:2,自引:0,他引:2  
赵捷  闻良珍  陈素华  凌霞珍 《中成药》2003,25(2):130-132
目的 :探讨中药金叶败毒颗粒 (金银花、鱼腥草、大青叶等 )对孕鼠免疫功能的作用 ,以及其对孕鼠和子代发育安全性的影响。方法 :设试验组、空白组和阳性组 3组 ,给试验组孕鼠孕期持续灌服高剂量的金叶败毒颗粒 ,观察各组仔鼠骨骼、器官和染色体发育情况 ;分别测定孕鼠分娩前外周血免疫细胞数、腹腔巨噬细胞数、脾淋巴细胞激活实验和NK细胞活性。结果 :三组孕鼠一般情况和仔鼠发育无明显差异 ;试验组孕鼠外周血免疫细胞、腹腔巨噬细胞数明显增多 ,脾淋巴细胞A值和NK细胞活性明显高于两对照组 (P <0 .0 5)。结论 :金叶败毒颗粒对孕鼠及子代无毒副作用 ,能显著提高孕鼠免疫功能 ,可对孕期发生的生理性免疫功能降低起保护作用  相似文献   
37.
目的:建立口腔愈疡颗粒的质量标准。方法:采用高效液相色谱法对成品中芍药苷进行含量测定。结果:芍药香浓度线性范围为:0.104—0.520μg/ml,γ=0.9993。样品平均回收率为98.85%,RSD为1.27%(n=5)。结论:该方法适用于口腔愈疡颗粒的质量控制。  相似文献   
38.
利巴韦林颗粒剂对小儿病毒性上呼吸道感染的疗效评价   总被引:1,自引:0,他引:1  
[目的] 评价利巴韦林颗粒剂(同欣颗粒)对小儿病毒性上呼吸道感染的疗效和安全性。[方法] 将446例病毒性上呼吸道感染儿童随机分为同欣颗粒治疗组(1组)和利巴韦林注射剂(病毒唑注射液)治疗组(Ⅱ组)。Ⅰ组共有病例235例,每日3次口服同欣颗粒,用药剂量为10mg/(kg.d);Ⅱ组为211例,每日2次肌肉注射病毒哩,剂量为10mg/(kg.d)。用χ2检验评定两组间在疗效和安全性方面的差异。[结果]Ⅰ组有194例为显效,显效率82.6%,不良反应发生率为4.7%;Ⅱ组显效人数为180例,显效率85.3%,不良反应发生率为5.2%。两组在疗效和不良反应方面无显著性差异,P>0.05。[结论]同欣颗粒在用于治疗小儿病毒性上呼吸道感染时,与病毒唑注射液的疗效和安全性基本相同。  相似文献   
39.
中药配方颗粒制备工艺研究思路   总被引:3,自引:0,他引:3  
陈天朝 《中国药业》2003,12(7):23-25
目的:探讨中药配方颗粒的制备工艺。方法:时中药配方颗粒的生产现状及存在的问题进行分析,对其制备工艺的基本原则进行了探讨。结果:以水为溶媒、煮提方法制备配方颗粒不完全符合中医药特点。汤剂中中药成分间的相互作用是达到增效降毒目的的重要途径之一。结论:为中药配方颗粒的制备提供参考。  相似文献   
40.
雪荔颗粒喷雾干燥法制备的工艺优化   总被引:4,自引:0,他引:4  
采用正交试验法,选定药液密度、进液速度和进风温度3因素,筛选雪荔颗粒喷雾干燥的最佳工艺。最佳工艺为药液密度1.07mg/ml(热测法),进液速度9ml/min,进风温度176℃。  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