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   8081篇
  免费   682篇
  国内免费   297篇
耳鼻咽喉   44篇
儿科学   223篇
妇产科学   204篇
基础医学   1391篇
口腔科学   143篇
临床医学   497篇
内科学   942篇
皮肤病学   106篇
神经病学   234篇
特种医学   135篇
外国民族医学   3篇
外科学   1496篇
综合类   1174篇
现状与发展   1篇
预防医学   269篇
眼科学   63篇
药学   633篇
  1篇
中国医学   188篇
肿瘤学   1313篇
  2024年   12篇
  2023年   83篇
  2022年   146篇
  2021年   300篇
  2020年   280篇
  2019年   353篇
  2018年   298篇
  2017年   346篇
  2016年   282篇
  2015年   340篇
  2014年   477篇
  2013年   480篇
  2012年   372篇
  2011年   498篇
  2010年   451篇
  2009年   400篇
  2008年   387篇
  2007年   437篇
  2006年   396篇
  2005年   369篇
  2004年   370篇
  2003年   292篇
  2002年   243篇
  2001年   212篇
  2000年   186篇
  1999年   189篇
  1998年   133篇
  1997年   108篇
  1996年   74篇
  1995年   78篇
  1994年   52篇
  1993年   48篇
  1992年   30篇
  1991年   17篇
  1990年   24篇
  1989年   16篇
  1988年   27篇
  1987年   12篇
  1986年   12篇
  1985年   26篇
  1984年   32篇
  1983年   28篇
  1982年   31篇
  1981年   16篇
  1980年   24篇
  1979年   21篇
  1978年   13篇
  1977年   7篇
  1976年   8篇
  1975年   8篇
排序方式: 共有9060条查询结果,搜索用时 484 毫秒
101.
P21WAF1/Cip1protein(p21)istheproductofwaf1gene,alsoknownascip1,sdi1[1,2].P21WAF1/Cip1isauniversalinhibitorofcyclin-dependentk...  相似文献   
102.
对 3 0例慢性粒细胞白血病 (CML)患者阿霉素诱导前后的 p53及 p2 1蛋白进行免疫组化染色分析 ,发现 7例在阿霉素诱导前即有 p53蛋白高表达 ,多为CML进展期患者 ,其中 6例对应的 p2 1蛋白在阿霉素诱导前后均为弱表达或不表达。 1例慢性期患者 p53及 p2 1在阿霉素诱导前后均无表达。此 7例患者预后差。  相似文献   
103.
Zusammenfassung. In einer experimentellen Studie wurde bei 10 Schweinen mit einem mittleren K?rpergewicht von 18,9 (15–24) kg eine intraven?se CO2- oder Argon-Embolie mit 10, 20 und 30 ml Gas durchgeführt. Das invasive Monitoring zeigte bei der Gasembolie mit Argon im Gegensatz zur Gasembolie mit CO2 einen st?rkeren Anstieg des pulmonal arteriellen Drucks (p < 0,001), einen st?rkeren Abfall des endexspiratorischen CO2 (p < 0,01), des Herzminutenvolumens (p < 0,01) und des mittleren arteriellen Drucks (p < 0,01). In der Argon-Gruppe (n = 5) starben zwei Tiere nach 20 bzw. 30 ml Bolusgabe. Ein weiteres Tier konnte nach Gabe von 30 ml Bolus erfolgreich reanimiert werden. In der CO2-Gruppe (n = 5) starb weder eines der Tiere noch war eine Reanimation erforderlich. Wenig l?sliche Gase wie Argon sollten in Situationen mit erh?htem Risiko einer Gasembolie nicht angewendet werden. ID=" Dr. T. Junghans Klinik f&uuml;r Allgemein-, Visceral-, Gef&auml;&szlig;- und Thoraxchirurgie Universit&auml;tsklinikum Medizinische Fakult&auml;t der Humboldt-Universit&auml;t Campus Charit&eacute; Mitte Schumannstra&szlig;e 20/21 D-10117 Berlin  相似文献   
104.
In congenital adrenal hyperplasia (CAR) due to 21-hydroxylase deficiency, measurement of plasma renin activity (PRA) has been the method of choice in diagnosing salt loss and in monitoring adequacy of mineralocorticoid replacement therapy. Due to methodological problems in PRA determinations, direct immunoradiometric assays for the measurement of active renin concentration have been developed. We measured PRA and active renin concentrations simultaneously in 39 patients with CAH (30 salt-wasting, 9 simple virilizing) to evaluate the potential role of this new method in the management of this disease. PRA was determined with an enzymatic assay (sample volume: 2 × 1000 l plasma), active renin concentration with a direct immunoradiometric assay (sample volume: 2 × 200 l plasma or serum). We found a highly significant correlation between active renin and PRA in our patients (P < 0.001), as previously shown in healthy subjects. Active renin was as reliable as PRA to assess the quality of mineralocorticoid replacement.  相似文献   
105.
Summary In the present paper a sensitive method is described to measure tetrahydronorharmane (THN) in the urine of man and rats as well as in the forebrain of rats. The compound is extracted into diethyl ether, separated by thin layer chromatography (TLC), acetylated with radiolabelled acetic anhydride and further isolated by two-dimensional TLC development. The existence of THN in urine of man was proven by using chromatography with different solvent systems, cocristallisation, isotope dilution technique as well as mass-spectrometry. The amount of THN in the urine varied over a wide range.With the same method it was demonstrated that THN occurs also in the forebrain of rats. The concentration increases after loading with tryptamine.The findings are discussed in view of the hypothesis that THN acts as a compound modulating neuronal mechanism.  相似文献   
106.
Two steroid 21-hydroxylase genes are normally present within the human major histocompatibility complex near the genes encoding the fourth component of complement (C4A and C4B). Steroid 21-hydroxylase is encoded by the CYP21 gene, while the highly homologous CYP21P gene is a pseudogene. We studied steroid 21-hydroxylase and complement C4 haplotypes in 33 Dutch patients (29 families) suffering form classical congenital adrenal hyperplasia (CAH) and in their 80 family members, and also in 55 unrelated healthy controls, using 21-hydroxylase and complement C4 cDNA probes. Eleven different haplotypes, defined in terms of gene deletions, gene duplications, conversions of CYP21 to CYP21P, and long and short C4 genes, were found. In 23% of the patients' haplotypes, the CYP21 gene was deleted; in 12%, it was converted into a CYP21P pseudogene. In the remaining 65%, the defect was apparently caused by a mutation not detectable by this method. The most common haplotype (with one CYP21 and one CYP21P gene) was significantly more often observed in patients with simple virilizing CAH than in those with salt-losing CAH. Comparison of the 21-hydroxylase haplotypes found in CAH patients from several countries shows evidence for considerable genetic variation between the groups studied.  相似文献   
107.
Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase (21-OHase) deficiency is inherited as an autosomal recessive trait. Patients can present with the salt wasting, simple virilizing or a non-classical form of the disease. The gene for P450C21, the enzyme carrying 21-OHase activity, has been mapped to the major histocompatibility complex on chromosome 6p. Using molecular hybridisation techniques we have studied the genetic defect in 27 families with one or more affected off-spring diagnosed and treated at the University Hospital of Essen. DNA samples were digested with restriction endonucleaseTaqI,PvuII,BglII, andEcoRI and analysed by Southern blot hybridisation with the cDNA probe pC21/3c. Eleven of 40 haplotypes associated with the salt wasting form were found to have a large deletion of 30 kb affecting the 5 end of the active 21-OHase gene and the 3 end of the closely linked pseudogene. Results in another 11 cases are compatible with gene conversion; 18 cases were not informative. The 30 kb deletion was associated with a combination of the HLA antigens Bw47 and DR7 in 7 of 11 cases. In the haplotypes with gene conversion, no linkage disequilibrium to HLA antigens was found. No apparent gene alterations were detected in simple virilizing and non-classical haplotypes. The direct detection of the genetic defect in 55% of the salt wasting haplotypes may help to improve predictive testing in families with CAH.  相似文献   
108.
葡萄胎p53、p21~(CIP1)及p185蛋白表达与恶变的关系   总被引:2,自引:0,他引:2  
目的 :探讨葡萄胎p5 3、p2 1CIP1及p185蛋白表达与恶变的关系及其临床特点。方法 :免疫组化法检测葡萄胎标本中p5 3、p2 1CIP1及p185蛋白的表达 ,以侵蚀性葡萄胎及绒癌为对照 ,并回顾性分析其临床资料。结果 :葡萄胎组p5 3、p2 1CIP1、p185蛋白阳性表达率分别为 35 % (35 / 10 0 ) ,71% (71/ 10 0 )及 36 % (36 / 10 0 ) ,与恶性对照组相比均有显著性差异 (P <0 .0 5 ) ;而完全性与部分性葡萄胎 ,完全性葡萄胎恶变组与非恶变组之间差异均无显著性 (P >0 .0 5 ) ,但恶变组p2 1CIP1表达有降低趋势。结论 :p5 3、p2 1CIP1及p185蛋白表达改变与葡萄胎恶变无确定关系 ,但可作为晚期现象出现于恶性滋养细胞肿瘤中 ,其中p2 1CIP1蛋白表达降低提示滋养细胞有向恶性转化的倾向  相似文献   
109.
Abstract: We used a N‐biotinylated peptide analog of the C‐terminal domain of the tumor suppressor protein, p21cip1/waf1 to elucidate peptide/protein interacting partners. The C‐terminal domain of p21cip1/waf1 protein spanning 141–160 amino acid residues is known to bind PCNA and this interaction is important in many biological processes including cell‐cycle control. This C‐terminal 20‐mer efficiently extracts PCNA in the presence of a variety of N‐ or C‐terminally attached affinity tags. Using difference silver stained 2D gels combined with in‐gel tryptic digests, we identified the difference spots using MALDI‐TOF mass spectrometry‐based peptide mass fingerprinting followed by a database search using profound against NCBIs human nonredundant protein sequence data bank. Identified spots include the p48 subunit of chromatin assembly factor‐1, the heat shock 70 protein analog BiP, calmodulin, nucleolin and a spot similar in size to dimeric PCNA. In contrast, microcapillary ion‐trap LC‐MS/MS analysis of a tryptic digest of entire affinity extracts derived from both control and experimental runs followed by database searches using sequest confirmed the presence of most of the above proteins. This strategy also identified hnRNPA1, HPSP90α, HSP40 and T‐complex protein 1, a protein similar to prothymosin, and a possible allelic variant of the p21cip1/waf1 protein. The use of N‐biotinylated peptide derived from the C‐terminal domain of p21cip1/waf1 protein in proteomic analysis exemplified here suggests that peptides obtained from intracellular functional screens could also potentially serve as efficient baits to discover new drug targets.  相似文献   
110.
乳腺癌ER、c-erbB2、P21、PCNA表达及其意义   总被引:3,自引:0,他引:3  
[目的]探讨ER、c-erbB2、p21、PCNA在乳腺癌的表达及其临床意义.[方法]应用免疫组化SP法,检测300例乳腺癌ER、c-erbB2、p21、PCNA表达.[结果]ER、c-erbB2、p21、PCNA在乳腺癌的阳性表达率分别为57.5%、47.3%、56%、663%;c-erbB2、p21、PCNA的表达随着组织分级升高而增强,ER的表达随着组织分级升高而降低;ER表达与生存期亦未见明确的关系,而c-erbB2、p21、PCNA阳性表达率与生存期呈负相关关系.[结论]ER、c-erbB2、p21、PCNA是判断乳腺癌分化程度、预后有价值的指标.  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