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   137350篇
  免费   14087篇
  国内免费   8707篇
耳鼻咽喉   1040篇
儿科学   1863篇
妇产科学   1421篇
基础医学   12844篇
口腔科学   2627篇
临床医学   19239篇
内科学   16343篇
皮肤病学   1651篇
神经病学   4910篇
特种医学   4636篇
外国民族医学   44篇
外科学   10600篇
综合类   29863篇
现状与发展   40篇
一般理论   8篇
预防医学   13029篇
眼科学   3709篇
药学   15595篇
  252篇
中国医学   11279篇
肿瘤学   9151篇
  2025年   26篇
  2024年   2028篇
  2023年   2702篇
  2022年   5502篇
  2021年   6774篇
  2020年   5785篇
  2019年   4317篇
  2018年   4136篇
  2017年   4589篇
  2016年   3864篇
  2015年   6369篇
  2014年   7809篇
  2013年   7995篇
  2012年   11937篇
  2011年   12586篇
  2010年   9686篇
  2009年   8056篇
  2008年   8839篇
  2007年   8519篇
  2006年   7510篇
  2005年   6661篇
  2004年   4439篇
  2003年   4092篇
  2002年   3343篇
  2001年   2603篇
  2000年   2180篇
  1999年   1670篇
  1998年   970篇
  1997年   998篇
  1996年   750篇
  1995年   636篇
  1994年   588篇
  1993年   343篇
  1992年   320篇
  1991年   304篇
  1990年   268篇
  1989年   209篇
  1988年   202篇
  1987年   179篇
  1986年   115篇
  1985年   90篇
  1984年   45篇
  1983年   41篇
  1982年   15篇
  1981年   11篇
  1980年   7篇
  1979年   15篇
  1975年   4篇
  1974年   3篇
  1973年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Pharmacokinetics and tissue distribution of crotonoside   总被引:1,自引:0,他引:1  
1.?Crotonoside is a bioactive ingredient from Croton Herba with a strong antitumour activity. This study aimed to develop a highly sensitive and selective high-performance liquid chromatography (HPLC) method to quantify crotonoside in biological samples for pharmacokinetics and distribution studies.

2.?Protein precipitation by perchloric acid was used to separate crotonoside from the biological samples, and the recovery rates for crotonoside and the internal standard (luteoloside) were >80%. All calibration curves examining the crotonoside levels in plasma and tissues were linear (all correlation coefficients >?0.99).

3.?The response to crotonoside appeared to be dose disproportional to the maximum plasma concentration and the area under the time–concentration curve in plasma over the range of 12.5–50.0?mg/kg, and crotonoside was highly distributed in tissues after intravenous administration. The highest crotonoside level was detected in the liver (28.79?±?14.96?μg/g), whereas crotonoside was undetected in the brain.  相似文献   
12.
Due to its chemical complexity, proper quality control for a Chinese medical preparation (CMP) has been a great challenge. Choosing the appropriate quality markers (Q-markers) for quality control of CMP is an important work. Best of all, the chosen Q-markers are the main chemical compounds from the herbals as well as the active constituents of this CMP. Only in this way the established quality control system can really achieve the purpose of controlling the quality of CMP and ensuring the safely and effectively use of CMP. To achieve the purpose, network pharmacology combined with the contents of chemical compounds in the CMP has been used in this research. We took an anti-arrhythmic CMP, Shenxian-Shengmai oral liquid (SSOL), as an example. Firstly, UPLC-QTOF-MS/MS method was used to analyze the main components of SSOL. A total of 64 compounds were unambiguously or tentatively identified and 32 of them were further validated by reference compounds. Secondly, the network was constructed based on the identified compounds to predict the effective compounds related to cardiac arrhythmias. Based on the existing database and the operation method of topology, a method of double network analysis (DNAA) was proposed, from which 10 important targets in the pathway of arrhythmia were screened out, and 26 compounds had good antiarrhythmic activity. Based on the prediction results of network pharmacology along with the contents of the compounds in this CMP, ten representative compounds were chosen as the Q-markers for the quality control of SSOL. We find that five of these ten compounds, including danshensu, rosmarinic acid, salvianolic acid A, epimedin A and icariin, have antiarrhythmic activity. Then, the UPLC-DAD method was established as the control method for SSOL.  相似文献   
13.
Poland is one of the countries distinguished by a long and colorful past. Undergoing numerous turbulent socio-economic changes forced by the course of history, Poland is now one of the member states of the European Union. Experiencing low water quantity and high contamination levels in surface waters, Poland is following other EU countries in the effort to reach a “good” water status. Herein are presented impacts of changes in Polish history on water legislation, management, and research, as well as explanations for the perceptible split between engineering and scientific approaches to the aquatic issues. Drawbacks caused by unsatisfactory state research funding for the sciences and division of the water related contemporary scientific interests are also discussed.  相似文献   
14.
目的 总结抗生素微生物检定法(管碟法)中影响测定结果准确性的常见系统误差并加以控制。方法 梳理10余年来中检院仲裁复验的案例,对共性问题进行整理,找出可能原因,并采用单一变量实验设计的方式加以确证。结果 估计效价和浓度比的错误计算、点样顺序和点样时间规范性和熟练程度、试验标准菌株的变异均会对管碟法测定结果产生影响。结论 通过细化实验操作规范,可以避免或尽量消除此类系统误差的影响。  相似文献   
15.
16.
17.
HPLC法测定四制香附丸中橙皮苷的含量   总被引:9,自引:4,他引:5  
邓茂芳  潘嬿 《安徽医药》2005,9(3):206-207
目的建立高效液相色谱测定四制香附丸中橙皮苷含量的方法.方法以十八烷基硅烷键合硅胶为填充剂;乙腈-0.2%磷酸水溶液(21:79)为流动相;检测波长为284 nm.结果线性关系为Y=1.9848 X 2.1951,相关系数r=0.9995,线性范围在70.24~561.92 ng,平均回收率101.34%(n=6),RSD=1.08%.结论本法操作简便准确,可作为四制香附丸中橙皮苷含量的质量控制方法.  相似文献   
18.
A deficiency of complement factor H may lead to excessive consumption of C3 and an increase in C3b deposition, which are important pathological characteristics of lupus nephritis. Complement factor H-related proteins (CFHRs), comprising CFHR1 to CFHR5 (CFHR1–5), are members of the wider factor H/CFHR family. Their role in lupus nephritis remains unclear. In this study, we compared circulating levels of CFHR1–5 in 152 patients diagnosed with lupus nephritis and 20 unrelated healthy individuals to explore the relationship between the expression of CFHR1–5 and development of the disease. We found that plasma levels of CFHR3 and CFHR5 were higher in patients with lupus nephritis than in healthy individuals; also, CFHR3 and CFHR5 concentrations increased with increasing systemic lupus erythematosus disease activity index (SLEDAI) values (P < 0.05). Pearson's and Spearman's correlation test results confirmed that plasma CFHR3 and CFHR5 levels in lupus nephritis patients were positively correlated with proteinuria and levels of creatinine (Cr) and anti-dsDNA (correlation coefficients = 0.491–0.717, P < 0.05), while they were negatively correlated with plasma C3 levels and eGFR [correlation coefficients = –(0.706–0.788), P < 0.05]. Receiver operating characteristic (ROC) curve analysis results confirmed that plasma CFHR3 and CFHR5 levels were predictive of SLEDAI values and disease end points (area under the curve = 0.664–0.884, P < 0.05), with patients with both high CFHR3 and high CFHR5 exhibiting the shortest progression-free survival. Thus, both CFHR3 and CFHR5 are of prognostic value in lupus nephritis status.  相似文献   
19.
目的探讨血糖、血脂水平与糖尿病视网膜病变患者视力损害的相关性。方法选取2016年1月至2018年1月我院内分泌科收治的250例DR患者进行研究。根据视力分级标准分为三个组:盲组(n=28),低视力组(n=80),低视力以上组(n=142)。比较各组患者FPG、HbAlC、TC、TG、LDL-C、HDL-C、LDL-C/HDL-C、ApoB、ApoA1、ApoB/ApoA1水平,对FPG、HbA1C、LDL-C/HDL-C及ApoB/ApoA1与DR患者视力损害进行Pearman相关性分析和Logistic回归分析。结果三组患者的TC、TG差异均无统计学意义(P>0.05);与低视力以上组相比,盲组和低视力组FPG、HbAlC、LDL-C、LDL-C/HDL-C、ApoB、ApoB/ApoA1更高,HDL-C、ApoA1更低(P<0.05);盲组FPG、HbAlC、LDL-C、LDL-C/HDL-C、ApoB、ApoB/ApoAl显著高于低视力组,HDL-C、ApoA1显著低于低视力组(P<0. 05)。经Spearman相关性分析,FPG、HbAlC、LDL-C/HDL-C、ApoB/ApoA1比值与DR患者视力损害均呈正相关。经Logistic回归分析,FPG、HbAlC、LDL-C/HDL-C、ApoB/ApoA1均是DR患者视力损害的独立危险因素。结论 FPG、HbAlC、LDL-C/HDL-C、ApoB/ApoA1与DR患者的视力损害有密切关系,通过监测这些指标有利于DR患者视力损害的预测,及时采取治疗措施。  相似文献   
20.
目的观察心可舒片治疗房颤合并焦虑状态患者的临床疗效及其对皮质醇和甲状腺素水平的影响。方法入选我院2017年1月至2017年10月收治的房颤合并焦虑状态患者34例,随机分为心可舒治疗组18例及对照组16例,治疗组予以心可舒片口服,观察治疗1月后两组患者的临床症状,并测定治疗前后的皮质醇和甲状腺素水平进行组间对比。结果治疗组患者临床症状较对照组进一步改善,且治疗组皮质醇激素水平较治疗前明显下降,与对照组相比差异具有统计学意义(P<0.05),治疗组T4水平较对照组升高(P<0.05),余甲状腺素水平两组患者差异无统计学意义。结论心可舒片可用于治疗房颤合并焦虑状态的患者,改善症状的同时可降低肾上腺皮质激素皮质醇及升高T4水平。  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