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   5258篇
  免费   205篇
  国内免费   105篇
耳鼻咽喉   9篇
儿科学   25篇
妇产科学   76篇
基础医学   855篇
口腔科学   120篇
临床医学   354篇
内科学   417篇
皮肤病学   59篇
神经病学   459篇
特种医学   320篇
外科学   205篇
综合类   504篇
预防医学   243篇
眼科学   48篇
药学   1479篇
中国医学   206篇
肿瘤学   189篇
  2023年   36篇
  2022年   82篇
  2021年   110篇
  2020年   91篇
  2019年   111篇
  2018年   87篇
  2017年   90篇
  2016年   89篇
  2015年   86篇
  2014年   223篇
  2013年   217篇
  2012年   278篇
  2011年   358篇
  2010年   257篇
  2009年   248篇
  2008年   236篇
  2007年   237篇
  2006年   206篇
  2005年   212篇
  2004年   201篇
  2003年   186篇
  2002年   146篇
  2001年   100篇
  2000年   98篇
  1999年   66篇
  1998年   57篇
  1997年   71篇
  1996年   85篇
  1995年   75篇
  1994年   70篇
  1993年   46篇
  1992年   58篇
  1991年   61篇
  1990年   34篇
  1989年   32篇
  1988年   45篇
  1987年   39篇
  1986年   31篇
  1985年   135篇
  1984年   114篇
  1983年   70篇
  1982年   101篇
  1981年   79篇
  1980年   76篇
  1979年   58篇
  1978年   49篇
  1977年   19篇
  1976年   19篇
  1975年   28篇
  1973年   26篇
排序方式: 共有5568条查询结果,搜索用时 15 毫秒
91.
目的:DABS-C1柱前衍生RP-HPLC法定量测定生理样本中的氨基酸。方法:采用DABS-C1柱前衍生RP-HPLC法,在紫外436nm处测定氨基酸。结果:人血清、脑脊液(CSF)和细胞培养液中的氨基酸在60min中得到良好的分离和测定。结论:DABS-C1柱前衍生RP-HPLC定量分析生理样本中的氨基酸,具有较好精准性,是一种比较疗便、稳定和可靠的检测方法。  相似文献   
92.
目的:评价丙泊酚中/长链脂肪乳预充注射液与注射液的经济性以及配置药师的满意度.方法:采用现场模拟试验法,由5名配置药师在静脉用药调配中心分别对2种注射液模拟手术室环境进行配置准备.比较2种注射液的配置时间,采用最小成本分析方法评价2种注射液配置的经济性,采用问卷调查方法调查配置药师的满意度,评分1~5分依次表示非常不满...  相似文献   
93.
黄家乐  王玥  何睿  裘畅  董铸雄 《中国药事》2017,31(10):1147-1152
目的:通过对比3家不同供应商的无菌预灌装培养平皿实验结果,筛选出质量较好的平皿培养基,同时探讨其供应商筛选、进厂检查和使用方法,为无菌药品生产企业进行无菌预灌装培养平皿的质量控制工作提供参考。方法:分别对3家供应商的无菌预灌装培养平皿进行3个批次的模拟使用,培养基无菌性、内层包装袋无菌性、平皿密闭性和培养基适用性检查,筛选适合用于无菌生产区洁净环境微生物监测的平皿培养基。结果:3家供应商的模拟使用、培养基无菌性和内层包装袋无菌性实验结果没有差异,供应商A的平皿密闭性和培养基适用性实验结果较另外两家更好。结论:本实验方法可用于筛选质量较好的无菌预灌装培养平皿。  相似文献   
94.

Ethnopharmacology relevance

Raw and processed Polygoni Multiflori Radix (PMR and PMRP) are used in the prevention and treatment of non-alcoholic fatty liver disease (NAFLD), hyperlipidemia or related diseases. In our previous research, 2, 3, 5, 4′-tetrahydroxy-stilbene-2-O-β-d-glucoside (TSG) displayed the most important role in the total cholesterol (TC) lowering effect among all the chemical constituents of Polygonum multiflorum. Emodin and physcion displayed more favorable triglyceride (TG) reducing effects than TSG. However, there are few researches focus on the approach and mechanism of how do Polygonum multiflorum exhibit good lipid regulation activity. The targeted sites of active substances of Polygonum multiflorum are still not clearly elucidated. This research pays close attention to how major chemical components of Polygonum multiflorum affect the TC and TG contents in liver cells.

Materials and methods

In this research, a sensitive, accurate and rapid in vitro model, steatosis hepatic L02 cell, was used to explore target sites of active chemical substances of Polygonum multiflorum for 48 h. Steatosis hepatic L02 cell was exposed to emodin, physcion and TSG, respectively. The contents of four key enzymes in the pathway of synthesis and decomposition of TC and TG were investigated after exposure. Meanwhile, the contents of lipid transfer protein were also tested. The diacylgycerol acyltransferase 1 (DGAT1) controlled the biosynthesis of TG from free fatty acids while 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase) limited the biosynthesis of TC. Hepatic triglyceride lipase (HTGL) and cholesterol 7α-hydroxylase (CYP7A) played the key role in the lipolysis procedure of TG and TC.

Results

The synthesis of TC and TG in steatosis L02 cells were apparently increased in the model group compared to the control group. Intracellular contents of HMG-CoA reductase and DGAT1 increased 32.33% and 56.52%, while contents of CYP7A and HTGL decreased 21.61% and 47.37%. Emodin, physcion and TSG all showed down-regulation effects on HMG-CoA reductase, while up-regulation effects on CYP7A. The most remarkable effect on HMG-CoA reductase was found on emodin. Emodin could reduce the DGAT1 content from 438.44±4.51 pg/mL in model group to 192.55±9.85 pg/mL (100 μm). The content of HTGL in 300 μm physcion group was 3.15±0.15 U/mL, which was more significantly effective than the control, lovastatin and fenofibrate group.

Conclusions

TSG could raise the content of CYP7A and then promote the lipolysis of cholesterol. Moreover, TSG also showed the best LDL-reducing effect. Emodin could inhibit HMG-CoA reductase and DGAT1, which were key enzymes in the synthesis of TC and TG. Physcion increased the content of HTGL, and then could boost the lipolysis of triglyceride. At the same time, physcion showed the best VLDL-reducing effect. In view of the above conclusions, we contributed the lipid regulation activity to an overall synergy of TSG, emodin and physcion.  相似文献   
95.
铁皮石斛试管苗壮苗培养基的研究   总被引:27,自引:3,他引:27  
刘骅  张治国 《中国中药杂志》1998,23(11):654-656
目的:研究铁皮石斛试管苗生产中,壮苗阶段的适宜培养基。方法:对基本培养基、天然提取物、香蕉提取物浓度和激素种类的选择进行了研究。结果:基本培养基以B5或1/2MS为好;天然提取物应选用香蕉水提物,香蕉水提物浓度为10%;植物激素是2mg/L的NAA较好。结论:以上培养基组成是铁皮石斛试管苗壮苗的适宜培养基。  相似文献   
96.

Aim of the study

As a traditional Chinese medicine, seed of Platycladus orientalis(Linnaeus) Franco has been extensively used as a tonic and sedative remedy. The present study was conducted to investigate whether lifespan was extended and the mechanisms of n-butanol extract from seed of Platycladus orientalis (BSPO) in Caenorhabditis elegans. The findings could provide the pharmacological basis for a treatment in traditional medicine.

Materials and methods

Lifespan extension by BSPO was evaluated under normal culture conditions and in a stress test. A possible mechanism of the anti-aging effect of BSPO, a change in the stress-resistance of related proteins, was also investigated in C. elegans.

Results

It has been shown that BSPO could significantly extend lifespan of C. elegans in a concentration dependent manner under normal culture conditions and stress. Further studies demonstrated that BSPO treatment significantly decreased reactive oxygen species (ROS) accumulation, up-regulated resistance to stress of related proteins, including glutathione S-transferase-4 (GST-4) and heat shock protein-16.2 (HSP-16.2), and reduced the amount of lipofuscin in transgenic C. elegans.

Conclusion

These results indicated that BSPO extended the lifespan, which could be attributed to its direct ROS scavenging activity, reducing the amount of lipofuscin and increasing the expression of gens associated with resistance to stress. These obtained data provided valuable support for traditional clinical practice to extend lifespan and to provide tonic remedy.  相似文献   
97.

Ethnopharmacological relevance

Velvet antlers (VA) have been claimed for centuries to have numerous medical benefits including strengthen bones. To investigate and compare the anti-osteoporotic activities from different sections of VA.

Materials and methods

Fresh VA prepared from farmed sika deers (Cervus nippon) was divided into upper (VAU), middle (VAM), and basal (VAB) sections. The chemical constituents and anti-osteoporotic effect of different sections from VA were evaluated using ovariectomized rats.

Results

Levels of water-soluble extracts, diluted alcoholic extract, amino acids, testosterone, insulin-like growth factor (IGF)-1and testosterone plus estradiol significantly differed among the different sections. Levels of these constituents were significantly higher in the upper section than in the basal section. Moreover, levels of testosterone and IGF-1 of the VAM were also significantly higher than those of the VAB. Calcium level increased downward from the tip with statistical significance. The strength of vertebrae increased in all VA-treated groups compared to the control, but only treatment with VAU and VAM increased the strength of the femur and the microarchitecure of the trabecular bone. Alkaline phosphatase levels of VAU- and VAM-treated groups significantly decreased, but osteocalcin did not significantly change. Moreover, VAU and VAM dose-dependently increased proliferation and mineralization of MC3T3-E1 cells.

Conclusion

Our study provides strong evidence for the regional differences in the effectiveness of velvet antler in treating osteoporosis. However, further studies are needed to elucidate the bioactive chemical constituents associated with the anti-osteoporotic effects of velvet antler.  相似文献   
98.
99.
Anti-bone resorption properties of the Korean herbal formulation, Gami-Honghwain (HJ), which comprises Carthamus tinctorius L. seed and hominis placenta, were investigated. We demonstrate that the production of PGE2 is inhibited by 20-100 microg/ml HJ in nontransformed osteoblastic cells (MC3T3-E1 cells), indicating that HJ inhibits PGE2 production. The effect of HJ on the proliferation and osteoblastic differentiation in MC3T3-E1 was also studied. HJ dose-dependently increased DNA synthesis (significant at 20-100 microg/ml), and increased alkaline phosphatase (ALP) and prolyl hydroxylase activities of MC3T3-E1 cells (20-100 microg/ml), while anti-estrogen tamoxifen eliminated the stimulation of proliferation and ALP activity of MC3T3-E1 which was induced by HJ. These results indicate that HJ directly stimulates cell proliferation and differentiation of osteoblasts. Also, when we assessed the effects of HJ on osteoblastic differentiation in MC3T3-E1, HJ enhanced ALP activity and mineralization in a dose- and time-dependent fashion. This stimulatory effect of the HJ was observed at relatively low doses (significant at 20-100 microg/ml and maximal at 100 microg/ml). Northern blot analysis showed that the HJ (60 microg/ml) increased in bone morphogenetic protein-2 as well as ALP mRNA concentrations in MC3T3-E1 cells. HJ (100 microg/ml) slightly increased in type I collagen mRNA abundance throughout the culture period, whereas it markedly inhibited the gene expression of collagenase-1 between days 15 and 20 of culture. These results indicate that HJ has anabolic effect on bone through the promotion of osteoblastic differentiation, suggesting that it could be used for the treatment of common metabolic bone diseases.  相似文献   
100.
ETHNOPHARMACOLOGICAL RELEVANCE: Buddleja globosa, known as "matico", is employed in Chile for wound healing. AIM OF THE STUDY: To validate the traditional use of the crude drug through in vivo and in vitro evaluation of the anti-inflammatory, analgesic and antioxidant properties of its extracts. MATERIALS AND METHODS: Sequential hexane, dichloromethane, methanol and total methanol extracts were studied using bioguided fractionation. The following activities were investigated: analgesic (writhing test), oral and topic anti-inflammatory (paw- and ear-induced edema), free radical scavenging and antioxidant activities (1,1-diphenyl-2-picrylhydrazyl, DPPH, superoxide anion, lipid peroxidation and xanthine oxidase inhibition). Sodium naproxen, nimesulide, indomethacin were used as reference drugs for in vivo, quercetin and allopurinol for in vitro assays. RESULTS: A mixture of alpha- and beta-amyrins was isolated from the hexane extract that showed 41.2% of analgesic effect at 600 mg/kg, inhibited by 47.7 and 79.0% the arachidonic acid (AA) and 12-deoxyphorbol-13-decanoate (TPA)-induced inflammation at 3mg/20 microL/ear, respectively. A mixture of beta-sitosterol, stigmasterol, stigmastenol, stigmastanol and campesterol was isolated from the fraction CD4-N and beta-sitosterol-glycoside from the fraction CD5-N, reducing TPA-induced inflammation by 78.2 and 83.7% at 1mg/20 microL/ear, respectively. The fraction CD4-N at 300 mg/kg also showed analgesic activity (38.7%). The methanol extract at 600mg/kg per os showed anti-inflammatory effect (61.4%), topic anti-inflammatory (56.7% on TPA) and analgesic activity (38.5%). Verbascoside and luteolin-7-O-glucoside were the major components of the methanol extract; apigenin 7-O-glucoside was also detected. Inhibition of superoxide anion, lipoperoxidation, and DPPH bleaching effect was found in the methanol serial and global extracts. CONCLUSIONS: The present report demonstrate the analgesic and anti-inflammatory properties of Buddleja globosa and validate its use in Chilean traditional medicine.  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