全文获取类型
收费全文 | 14740篇 |
免费 | 896篇 |
国内免费 | 175篇 |
专业分类
耳鼻咽喉 | 378篇 |
儿科学 | 269篇 |
妇产科学 | 203篇 |
基础医学 | 2355篇 |
口腔科学 | 237篇 |
临床医学 | 1112篇 |
内科学 | 2884篇 |
皮肤病学 | 468篇 |
神经病学 | 1050篇 |
特种医学 | 943篇 |
外科学 | 2271篇 |
综合类 | 108篇 |
现状与发展 | 1篇 |
一般理论 | 2篇 |
预防医学 | 540篇 |
眼科学 | 483篇 |
药学 | 1124篇 |
中国医学 | 167篇 |
肿瘤学 | 1216篇 |
出版年
2024年 | 10篇 |
2023年 | 85篇 |
2022年 | 327篇 |
2021年 | 478篇 |
2020年 | 237篇 |
2019年 | 356篇 |
2018年 | 462篇 |
2017年 | 325篇 |
2016年 | 495篇 |
2015年 | 718篇 |
2014年 | 860篇 |
2013年 | 955篇 |
2012年 | 1348篇 |
2011年 | 1227篇 |
2010年 | 782篇 |
2009年 | 612篇 |
2008年 | 871篇 |
2007年 | 841篇 |
2006年 | 795篇 |
2005年 | 671篇 |
2004年 | 529篇 |
2003年 | 470篇 |
2002年 | 451篇 |
2001年 | 257篇 |
2000年 | 202篇 |
1999年 | 159篇 |
1998年 | 86篇 |
1997年 | 69篇 |
1996年 | 57篇 |
1995年 | 53篇 |
1994年 | 40篇 |
1993年 | 39篇 |
1992年 | 94篇 |
1991年 | 102篇 |
1990年 | 83篇 |
1989年 | 67篇 |
1988年 | 69篇 |
1987年 | 99篇 |
1986年 | 66篇 |
1985年 | 61篇 |
1984年 | 38篇 |
1983年 | 35篇 |
1982年 | 27篇 |
1981年 | 21篇 |
1980年 | 14篇 |
1979年 | 22篇 |
1978年 | 36篇 |
1976年 | 11篇 |
1975年 | 11篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The effect of the root ofCoptis japonica (COPT), both the dichloromethane soluble (CH2Cl2) and insoluble (H2O) fractions, on catecholamine contents and tyrosine hydroxylase (TH) activity in PC12 cells was investigated. CH2Cl2 and H2O fractions showed 21 and 53% inhibitions on dopamine content, respectively, at a concentration of 40 μg/ml in medium: the H2O fraction provided a greater inhibitory effect. The TH activity was reduced by the treatment of COPT (H2O fraction). These results suggest that COPT has an inhibitory effect on the catecholamine biosynthesis by the reduction of TH activity in PC12 cells. 相似文献
62.
The activity of S-famesylcysteine O-methyltransferase was assayed by incubating the enzyme with a syntheticin vitro substrate, [N-acetyl-S-trans, trans-famesyl-L-cysteine (AFC)], together with S-adenosyl-L-[methyl-14C]methionine. The resulting methylesterification product, [N-acetyl-S-trans, trans-famesyl-L-cysteine (methyl-14C) ester (AFCME)], was then analyzed either directly on HPLC or by converting the AFC[methyl-14C]ME to [methyl-14C] alcohol by basehydrolysis. Employing these two analytical methods, it was established that a peptide purified from rat liver cytosol fraction [Int. J. Biochem., 25, 1157 (1993)] strongly inhibited the above enzyme activity with IC50 of 7.1X10?8 M. Also, the S-famesylcysteine O-methyltransferase from several human colon cancer cells was also equally inhibited by the peptide. 相似文献
63.
64.
Metabolism and excretion of atorvastatin in rats and dogs. 总被引:1,自引:0,他引:1
Atorvastatin (AT) is a second-generation potent inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase, clinically approved for lowering plasma cholesterol. Using a mixture of [D(5)/D(0)] AT and/or [(14)C]AT, the metabolic fate and excretion of AT were examined in rats and dogs following single and multiple oral doses. Limited biliary recycling was examined in one dog after a single dose of AT. AT-derived metabolites in bile samples were identified by metabolite screening of the [D(5)/D(0)] AT molecular clusters using tandem mass spectrometry. Bile was a major route of [(14)C] drug-derived excretion, accounting for 73 and 33% of the oral dose in the rat and dog, respectively. The remaining radioactivity was recovered in the feces; only trace amounts were excreted in urine. Radioactive components identified in rat and dog bile were the para- and ortho-hydroxy metabolites, a glucuronide conjugate of ortho-hydroxy AT, and unchanged AT. Two minor radioactive components were identified as beta-oxidation products of AT with one confirmed as a beta-oxidized AT derivative. The reappearance of AT and major metabolites in bile from a dog administered a sample of its previously excreted bile indicated biliary recycling is an important component in AT metabolism. Multiple dose administration in rats did not alter biliary metabolic profiles. Rat and dog plasma profiles after multiple dose administration were similar and showed no additional metabolites not found in bile. Examination of rat and dog bile and plasma indicates that AT primarily undergoes oxidative metabolism. 相似文献
65.
Lim YH Leem MJ Shin DH Chang HB Hong SW Moon EY Lee DK Yoon SJ Woo WS 《Archives of pharmacal research》1999,22(2):208-212
Activity-guided fractionation of the roots of Anthriscus sylvestris resulted in the isolation and characterization of five cytotoxic compounds, deoxypodophyllotoxin (1), falcarindiol (2), and angeloyl podophyllotoxin (5) from the hexane soluble fraction and morelensin (3), bursehernin (4) from the chloroform soluble fraction. It is the first report of the occurrence of compound 5 in nature. 相似文献
66.
Yong -Hyun Kim Do -Youn Won Chang -Young Oh Nam -Tae Woo Young -Ho Park Jin -Hyun Jeong Won -Hun Ham 《Archives of pharmacal research》1999,22(3):300-301
Stereoselective synthesis of (+/-)-epibatidine analog 2, which contains the 8-azabicyclo[3.2.1]octane ring system, was achieved by using palladium-catalyzed Heck-type coupling reaction from 3. 相似文献
67.
Hak Cheol Kwon Byeong Gon Lee Seung Hee Kim Chil Mann Jung Sung Youl Hong Jeung Whan Han Hyang Woo Lee Ok Pyo Zee Kang Ro Lee 《Archives of pharmacal research》1999,22(4):410-413
In bioassay-guided search for inducible nitric oxide synthase (iNOS) inhibitory compounds from higher plants of South Korea, two beta-carboline alkaloids, 4-methoxy-1-vinyl-beta-carboline (1) and 4,8-dimethoxy-l-vinyl-beta-carboline (2) have been isolated from the cortex of Melia azedarach var. japonica. The structures of these compounds were elucidated on the basis of spectroscopic data. Compounds 1 and 2 showed marked inhibitory activity of iNOS on LPS- and interferon-gamma-stimulated RAW 264.7 cells. 相似文献
68.
Cytotoxicity of urushiols isolated from sap of Korean lacquer tree (Rhus vernicifera stokes) 总被引:1,自引:0,他引:1
Hong DH Han SB Lee CW Park SH Jeon YJ Kim MJ Kwak SS Kim HM 《Archives of pharmacal research》1999,22(6):638-641
Cytotoxicities of four urushiols, congeners isolated from the sap of Korean lacquer tree (Rhus vernicifera Stokes), to 29 human cancer cell lines originated from 9 organs were evaluated. Their values of 50% growth inhibition were below 4 microg/ml, and showed cell line specific cytotoxicity. The present result is the first report on the cytotoxicity of urushiols suggesting that they would have an anticancer activity to human cancer cells. 相似文献
69.
E. Y. Liang W. W. M. Lam J. K. S. Woo C. A. van Hasselt C. Metreweli 《European radiology》1996,6(4):553-556
In order to study the features of sinonasal polyposis (SNP) on CT, 100 consecutive coronasal sinus CT examinations done for chronic inflamamtory sinonasal disease were reviewed. The CT findings of the 27 fully documented SNPs were analyzed. All our SNPs were bilateral. There was a strong tendency for extensive involvement. Nasal polyps were seen in 22 of 27 (81%); bony trabecular deossification in 23 of 27 (85%); widening of infundibulum in 26 of 27(96%). We discovered a new sign truncation of the bony middle turbinate, where the bulbous part of bony middle turbinate was missing, in 51 of 26 (58 %) of SNP patients without a previous history of middle turbinectomy, 12 of 15(80%) were bilateral. The one SNP patient (1 of 27) with previous middle turbinectomy was not regarded to be real truncation. Truncation of the bony middle turbinate is a characteristic and easily recognizable ancillary sign, and is not seen in other patterns of sinusitis. Together with other features on coronal sinus CT, this adds diagnostic confidence in diagnosing sinonasal polyposis.
Correspondence to: E. Y. Liang 相似文献
70.
Relation between genotype and phenotype in Swedish phenylketonuria and hyperphenylalaninemia patients 总被引:6,自引:0,他引:6
E. Svensson U. von Döbeln R. C. Eisensmith L. Hagenfeldt S. L. C. Woo 《European journal of pediatrics》1993,152(2):132-139
Phenylketonuria (PKU) and hyperphenylalaninemia (HPA) are caused mostly by an inherited (autosomal recessive) deficiency in hepatic phenylalanine hydroxylase (PAH) activity. More than 50 PAH mutations have ben reported. The goal of the present study was to examine the molecular basis for the clinical heterogeneity of Swedish PKU and HPA patients. Mutations were identified through allele-specific oligonucleotide hybridization or DNA sequencing on 128 of the 176 mutant alleles (73%). Three mutations (R408W, Y414C and IVS12) together accounted for 56% of all mutant alleles and ten relatively infrequent mutations were found on another 17% of all mutant alleles. Patients from 50 of the 88 families (57%) had identified mutations in both PAH genes and allowed use to compare the clinical effects of different combinations of PAH mutations. The in vitro activity of all of these mutations, including the newly identified G272X and L364, have been tested in a eukaryotic expression system. There was a strong relationship between the average in vitro PAH activity of the two mutant enzymes and both the phenylalanine tolerance and the neonatal pretreatment serum phenylalanine concentration. This confirms previous observations in Danish and German PKU patients that disease phenotype is a consequence of the nature of the mutations at the PAH locus and not significantly influenced by other loci. The sample population in the previous study did not, however, include mild HPA patients, and the observed correlation is thus restricted to severe and moderate mutant alleles. Since a comparatively high proportion of the Swedish patients were mildly affected, we have provided additional evidence that this correlation is valid throughout a continuous spectrum of clinical varieties. PAH genotyping could therefore help predict prognosis of a recently diagnosed PKU or HPA child. 相似文献