全文获取类型
收费全文 | 9205篇 |
免费 | 473篇 |
国内免费 | 334篇 |
专业分类
耳鼻咽喉 | 23篇 |
儿科学 | 104篇 |
妇产科学 | 464篇 |
基础医学 | 1806篇 |
口腔科学 | 115篇 |
临床医学 | 554篇 |
内科学 | 1358篇 |
皮肤病学 | 85篇 |
神经病学 | 1011篇 |
特种医学 | 124篇 |
外科学 | 625篇 |
综合类 | 1211篇 |
预防医学 | 417篇 |
眼科学 | 53篇 |
药学 | 853篇 |
1篇 | |
中国医学 | 486篇 |
肿瘤学 | 722篇 |
出版年
2024年 | 14篇 |
2023年 | 131篇 |
2022年 | 262篇 |
2021年 | 200篇 |
2020年 | 155篇 |
2019年 | 170篇 |
2018年 | 165篇 |
2017年 | 200篇 |
2016年 | 197篇 |
2015年 | 192篇 |
2014年 | 416篇 |
2013年 | 555篇 |
2012年 | 444篇 |
2011年 | 498篇 |
2010年 | 506篇 |
2009年 | 484篇 |
2008年 | 522篇 |
2007年 | 473篇 |
2006年 | 480篇 |
2005年 | 416篇 |
2004年 | 415篇 |
2003年 | 380篇 |
2002年 | 341篇 |
2001年 | 315篇 |
2000年 | 255篇 |
1999年 | 223篇 |
1998年 | 192篇 |
1997年 | 167篇 |
1996年 | 176篇 |
1995年 | 161篇 |
1994年 | 138篇 |
1993年 | 104篇 |
1992年 | 96篇 |
1991年 | 67篇 |
1990年 | 59篇 |
1989年 | 60篇 |
1988年 | 34篇 |
1987年 | 34篇 |
1986年 | 25篇 |
1985年 | 44篇 |
1984年 | 35篇 |
1983年 | 16篇 |
1982年 | 38篇 |
1981年 | 32篇 |
1980年 | 24篇 |
1979年 | 19篇 |
1978年 | 40篇 |
1977年 | 13篇 |
1976年 | 12篇 |
1974年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
面口部炎性刺激条件下PPTA mRNA在大鼠三叉神经脊束核尾侧亚核神经元中的表达变化及与FOS的共存 总被引:1,自引:0,他引:1
将鹿角菜胶注射到大鼠口周皮下作成炎性刺激模型,用原位杂交法结合免疫组化法观察了三叉神经尾侧亚核中PPTAmRNA的表达变化及其与FOS蛋白表达的关系。结果发现:鹿角菜胶注射后,注射侧三叉神经尾侧亚核浅层内PPTAmRNA阳性神经元的数量与对照例相比明显增多。鹿角菜胶产生的炎性刺激也诱导了FOS蛋白在三叉神经尾侧亚核中的表达,FOS蛋白阳性神经元主要位于刺激侧三叉神经尾侧亚核浅层,而对照侧仅有少量分布。在三叉神经尾侧亚核浅层约60%的PPTAmRNA阳性神经元同时表达了FOS蛋白,而双重反应阳性的神经元仅占FOS阳性神经元的30%。上述结果提示:在面口部伤害性刺激诱导的三叉神经尾侧亚核内PPTAmRNA增强表达的过程中,FOS蛋白可能起着重要的调节作用。 相似文献
102.
Jakob CA Guldenschuh I Hürlimann R Müllhaupt B Müller A Ammann R Fried M Roth J 《Virchows Archiv : an international journal of pathology》1999,434(1):57-62
DNA methylation plays an important part in the regulation of gene expression. Alterations in DNA methylation in tumours have
been reported and have been used to generate hypotheses about mutagenesis and silencing of tumour suppressor genes. However,
the underlying mechanism is still poorly understood, and conflicting data on the levels of overexpression of 5′-cytosine DNA
methyltransferase in sporadic colon carcinoma have been published. We used a competitive RT-PCR assay for quantification of
mRNA of 5′-cytosine DNA methyltransferase in colon biopsies obtained from patients with hereditary colon carcinoma syndromes
and compared the results with those obtained in a control group. No significant difference was found between the flat mucosa
of FAP patients and the mucosa of the control group. In FAP and HNPCC patients, the 5′-cytosine DNA methyltransferase mRNA
levels of adenomas were significantly higher (P<0.05) than of flat mucosa in the same group, but both showed great variability from patient to patient. Our findings suggest
that the mRNA levels of methyltransferase cannot be used as predictive marker for screening in families affected by hereditary
colon carcinoma.
Received: 20 July 1998 / Accepted: 21 September 1998 相似文献
103.
Interleukin-2 receptor gene expression in kidney transplant recipients treated with cyclosporin A.
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
N Yoshimura T Oka T Amagai Y Horii J Imanishi 《Clinical and experimental immunology》1991,85(2):326-330
We examined the effects of cyclosporin A (CsA) administered in vivo on the capacity of peripheral blood mononuclear cells (PBMC) from kidney transplant recipients to express IL-2 receptor (IL-2R) gene at the level of mRNA after mitogen stimulation in vitro. There were no differences in the percentage of IL-2R+ cells among the groups of normal individuals, azathioprine-prednisolone treated, and CsA-prednisolone-treated recipients, using FITC-labelled monoclonal anti-IL-2R antibody (anti-alpha chain): 40.3 +/- 10.1% and 62.8 +/- 11.1% of normal PBMC (n = 18), 37.0 +/- 9.3% and 61.7 +/- 5.8% of PBMC from azathioprine-prednisolone-treated recipients (n = 20), and 37.7 +/- 9.6% and 60.7 +/- 12.7% of PBMC from CsA-prednisolone-treated recipients (n = 20) expressed IL-2R after 24 h and 48 h of phytohaemagglutinin stimulation, respectively. However, in a study of Northern blotting using cDNA for IL-2R (anti-alpha chain specific), both the 3500 and 1400 bp families of IL-2R mRNA were remarkably decreased in PBMC from CsA-prednisolone-treated recipients compared with azathioprine-prednisolone-treated recipients and normal individuals. These studies demonstrated that CsA could inhibit IL-2R gene expression at the level of mRNA at physiological concentration. 相似文献
104.
105.
Human telomerase catalytic subunit gene re-expression is an early event in oral carcinogenesis 总被引:4,自引:0,他引:4
AIMS: Detection of telomerase catalytic subunit (hTERT) mRNA has been used as a surrogate marker for estimation of telomerase activity. The exact role and timing of telomerase re-activation, a key enzyme implicated in cellular immortalization and transformation, in the multistep process of oral carcinogenesis is still unknown. The aim was to test the hypothesis that (i) quantitative rather than qualitative differences exist in the level of hTERT mRNA expression between normal oral mucosa, different grades of oral epithelial abnormalities and squamous cell carcinomas of the oral cavity, and that (ii) hTERT gene re-expression is an important, probably early event in oral carcinogenesis. METHODS AND RESULTS: The relative quantity of hTERT mRNA was analysed in 45 frozen oral epithelia representing different morphological stages of oral carcinogenesis classified according to the Ljubljana classification and in 37 oral squamous cell carcinomas, using a commercially available LightCycler Telo TAGGG hTERT Quantification kit. hTERT mRNA was not detected in normal or reactive hyperplastic oral epithelia, but was present in 43% of atypical hyperplasias (premalignant lesions), 60% of intraepithelial carcinomas and 68% of oral squamous cell carcinomas. Statistical analysis revealed two groups of oral epithelial changes, with significant differences in the levels of hTERT mRNA expression: 1, normal and reactive hyperplastic oral epithelium, and 2, atypical hyperplasia, intraepithelial carcinomas and squamous cell carcinomas. CONCLUSION: These data suggest that hTERT gene re-expression represents an early event in the multistep process of oral carcinogenesis, already detectable at the stage of precancerous oral epithelial changes. Nevertheless, other genetic aberrations appear to be necessary for progression of oral epithelial abnormalities towards invasive squamous cell carcinoma. 相似文献
106.
Allen LA Achermann JC Pakarinen P Kotlar TJ Huhtaniemi IT Jameson JL Cheetham TD Ball SG 《Human reproduction (Oxford, England)》2003,18(2):251-256
BACKGROUND: Inactivating mutations of the FSH receptor (FSHR) are a rare cause of hypergonadotrophic hypogonadism in women. Only one patient with primary amenorrhoea due to an FSHR gene mutation has been reported outside of Finland, where the prevalence of Ala189Val mutations is particularly high. METHODS AND RESULTS: Here, we describe the clinical, molecular genetic and functional characteristics associated with a novel inactivating mutation in exon 10 of the FSHR gene identified in a patient who presented with primary amenorrhoea at 17 years of age. The C to G transversion found at nucleotide 1043 causes a Pro348Arg substitution in the extracellular region of the FSHR and results in a mutant FSHR that is completely inactive in functional studies and that does not bind FSH. The proband exhibits apparent homozygosity for this recessive mutation. Her father is heterozygous for the mutation while analysis of exon 10 of the FSHR gene from her mother revealed only wild-type sequence. Chromosome painting was used to exclude deletions or rearrangements of 2p, and microsatellite markers did not show paternal uniparental isodisomy for this region. These findings suggest that the proband is hemizygous, with an inherited or de-novo microdeletion, or alternatively a de-novo gene conversion, of the accompanying FSHR allele. CONCLUSIONS: This case confirms the importance of the FSHR in female pubertal development and reproduction, and supports a relationship between phenotype and function for FSHR mutations. 相似文献
107.
La Marca A Giulini S Orvieto R De Leo V Volpe A 《Human reproduction (Oxford, England)》2005,20(6):1569-1572
BACKGROUND: In females, anti-Müllerian hormone (AMH) is expressed only by the ovary. AMH is secreted by the granulosa cells of ovarian follicles and appears to regulate early follicle development. AMH is detected in serum from women of reproductive age and its levels vary slightly with the menstrual cycle, reaching the peak value in the late follicular phase. This study investigated serum AMH levels throughout gestation and after delivery in healthy pregnant women. METHODS: This cross-sectional study recruited pregnant women and healthy non-pregnant women, 84 in total. AMH, FSH and E2 were measured in the follicular phase, in the three trimesters of pregnancy and in early puerperium. RESULTS: Estradiol and FSH levels followed the expected patterns during gestation. During the follicular phase of the menstrual cycle AMH levels were 1.9 +/- 0.5 ng/ml. In the three trimesters of pregnancy and in early puerperium AMH levels were: 2.1 +/- 0.56, 2.4 +/- 0.64, 1.95 +/- 0.6 and 2.05 +/- 0.55 ng/ml respectively. No significant modifications were found in AMH levels during pregnancy and in the early puerperium. CONCLUSIONS: This study has obtained information on AMH and on the possible relationship with FSH. We hypothesize that the profile of the new marker of ovarian activity AMH may indicate that initial non-cyclic ovarian follicular activity during pregnancy is not abolished. Moreover FSH, does not seem to play a direct role on AMH synthesis and secretion. 相似文献
108.
目的:建立一种灵敏度高、特异性强、定量、精确、操作简便的微孔板酶联夹心杂交技术,定量检测人IL-8 mR-NA。方法:针对人IL-8 mRNA逆转录聚合酶链反应产物一条链的不同区域序列设计一对特异探针,其中一条为捕获探针,5′端用活性氨基修饰,与微量DNA结合板表面的NOS基团共价结合,“竖直”地包被在微孔板内;另一条检测探针的3′端标记生物素,和辣根过氧化物酶结合。提取人外周血单个核细胞总RNA,进行RT-PCR扩增IL-8 mRNA,双链DNA产物经热变性后加入已包被捕获探针的微孔板内进行杂交,加入检测探针与已杂交的产物结合,经亲和素-辣根过氧化物酶系统检测杂交信号。结果:该法灵敏度为检出16个循环的PCR产物、5×103个PBMCs中的IL-8 mRNA、检测PCR终产物的最高稀释倍数为1∶256阳性;特异性试验非目的扩增片段酶联杂交检测未检出阳性杂交信号;精密度试验CV为5.2%。结论:该方法具有操作简便、灵敏度高、特异性强等优点,适合IL-8 mRNA PCR扩增产物的定量检测。 相似文献
109.
In situ localization of mRNA for the fibrinolytic factors uPA, PAI-1 and uPAR in endometriotic and endometrial tissue 总被引:4,自引:0,他引:4
Endometriotic tissue grows invasively. The plasminogen-activating system is suggested to participate in degradation of extracellular matrix (ECM) and modulation of cell adhesion and migration. We have previously demonstrated elevated levels of the fibrinolytic factors urokinase plasminogen activator (uPA) and plasminogen activator inhibitor (PAI-1) in endometriotic tissue and endometrium from women with endometriosis. The aim of the present study was to localize the uPA, PAI-1 and urokinase plasminogen activator receptor (uPAR) mRNA in endometriotic tissue and in endometrium both from women with and without endometriosis. With in situ hybridization, we found that uPA mRNA seems to be up-regulated in endometriotic glands and endometrial stroma as well as PAI-1 mRNA in endometriotic and endometrial stroma from women with endometriosis. uPAR mRNA likewise appears to be up-regulated in both glands and stroma in endometriotic tissue and in endometrial glands from patients compared to endometrial glands and stroma from healthy women. These differences might be important for menstrual shedding and adherence of endometrial fragments to peritoneal lining in women developing endometriosis and for the invasive growth of endometriotic tissue. 相似文献
110.
A multicentre, open-label, randomized study of the gonadotrophin-releasing hormone (GnRH) antagonist ganirelix (Orgalutran((R))/Antagon((TM))) was performed in women undergoing ovarian stimulation with recombinant FSH (rFSH: Puregon((R))). The study was designed as a non-inferiority study using a long protocol of buserelin (intranasal) and rFSH as a reference treatment. A total of 730 subjects was randomized in a treatment ratio of 2:1 (ganirelix:buserelin) using an interactive voice response system which stratified for age, type of infertility and planned fertilization procedure [IVF or intracytoplasmic sperm injection (ICSI)]. The median duration of GnRH analogue treatment was 5 days in the ganirelix group and 26 days in the buserelin group, whereas the median total rFSH dose was 1500 IU and 1800 IU respectively. In addition, in the ganirelix group the mean duration of stimulation was 1 day shorter. During ganirelix treatment the incidence of LH rises (LH >/=10 IU/l) was 2.8% versus 1.3% during rFSH stimulation in the buserelin group. On the day of triggering ovulation by human chorionic gonadotrophin (HCG), the mean number of follicles >/=11 mm diameter was 10.7 and 11.8, and the median serum oestradiol concentrations were 1190 pg/ml and 1700 pg/ml in the ganirelix and buserelin groups respectively. The mean number of oocytes per retrieval was 9.1 and 10.4 respectively, whereas the mean number of good quality embryos was 3.3 and 3.5 respectively. The fertilization rate was equal in both groups (62.1%), and the same mean number of embryos (2.2) was replaced. The mean implantation rates were 15.7% and 21.8%, and the ongoing pregnancy rates per attempt were 20.3% and 25.7% in the ganirelix and buserelin groups respectively. Evaluation of all safety data indicated that the ganirelix regimen was safe and well tolerated. The overall incidence of ovarian hyperstimulation syndrome was 2.4% in the ganirelix group and 5.9% in the reference group. The results of this study support a safe, short and convenient treatment regimen of ganirelix, resulting in a good clinical outcome for patients undergoing ovarian stimulation for IVF or ICSI. 相似文献