全文获取类型
收费全文 | 41891篇 |
免费 | 3337篇 |
国内免费 | 1238篇 |
专业分类
耳鼻咽喉 | 192篇 |
儿科学 | 976篇 |
妇产科学 | 523篇 |
基础医学 | 6491篇 |
口腔科学 | 871篇 |
临床医学 | 2897篇 |
内科学 | 6512篇 |
皮肤病学 | 714篇 |
神经病学 | 3531篇 |
特种医学 | 633篇 |
外国民族医学 | 5篇 |
外科学 | 3329篇 |
综合类 | 5654篇 |
现状与发展 | 4篇 |
预防医学 | 1987篇 |
眼科学 | 500篇 |
药学 | 6470篇 |
4篇 | |
中国医学 | 2003篇 |
肿瘤学 | 3170篇 |
出版年
2024年 | 94篇 |
2023年 | 820篇 |
2022年 | 2015篇 |
2021年 | 1905篇 |
2020年 | 1441篇 |
2019年 | 1589篇 |
2018年 | 1575篇 |
2017年 | 1458篇 |
2016年 | 1330篇 |
2015年 | 1413篇 |
2014年 | 2288篇 |
2013年 | 2518篇 |
2012年 | 2065篇 |
2011年 | 2518篇 |
2010年 | 1977篇 |
2009年 | 2007篇 |
2008年 | 2004篇 |
2007年 | 1783篇 |
2006年 | 1646篇 |
2005年 | 1534篇 |
2004年 | 1446篇 |
2003年 | 1253篇 |
2002年 | 1083篇 |
2001年 | 821篇 |
2000年 | 797篇 |
1999年 | 697篇 |
1998年 | 562篇 |
1997年 | 574篇 |
1996年 | 501篇 |
1995年 | 467篇 |
1994年 | 401篇 |
1993年 | 291篇 |
1992年 | 241篇 |
1991年 | 246篇 |
1990年 | 185篇 |
1989年 | 155篇 |
1988年 | 167篇 |
1987年 | 132篇 |
1986年 | 143篇 |
1985年 | 288篇 |
1984年 | 304篇 |
1983年 | 239篇 |
1982年 | 269篇 |
1981年 | 214篇 |
1980年 | 198篇 |
1979年 | 181篇 |
1978年 | 135篇 |
1977年 | 94篇 |
1976年 | 103篇 |
1975年 | 91篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
151.
重组人白细胞介素6对SW872脂肪细胞增殖和凋亡的影响 总被引:4,自引:4,他引:0
目的 探讨白细胞介素 6(IL 6)对SW872脂肪细胞增殖及凋亡的影响。方法 体外培养SW872脂肪细胞 ,0 .6mmol/L油酸诱导SW872前脂肪细胞分化 ,化学比色法检测细胞内三酰甘油的总量 ;油红O染色观察细胞内脂肪的聚积 ;MTT法检测不同浓度IL 6对SW872前脂肪细胞增殖活力的影响 ;流式细胞仪分析IL 6对SW872成熟脂肪细胞凋亡的影响。结果 0 .6mmol/L油酸刺激 72h ,几乎 10 0 %SW872前脂肪细胞分化为成熟的脂肪细胞 ,细胞内三酰甘油的含量明显增加 ,油红O染色胞浆内可见丰富的脂滴 ;5 μg/LIL 6对SW872前脂肪细胞的增殖没有影响 ,10~ 5 0 μg/LIL 6明显抑制SW872前脂肪细胞的增殖 ;IL 6对SW872成熟脂肪细胞的凋亡无影响。结论 IL 6能明显抑制SW872前脂肪细胞的增殖 ,其抑制效应呈剂量依赖性 ,表明IL 6可能与肥胖有关 ,高剂量IL 6可降低肥胖的程度。 相似文献
152.
Tetsuji Fujita Katsuhiko Yanaga 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》2007,392(2):127-130
BACKGROUND: Although there is increasing evidence suggesting that the vagus nerve functions as a connector between the nervous and immune systems in animals, little is known about the role of the vagus nerve in postoperative acute phase response in humans. MATERIALS AND METHODS: The extent of fever and acute phase protein response and the production of inflammatory cytokine during the early postoperative period were compared among the patients who had undergone total gastrectomy including truncal vagotomy (n = 13), those having distal gastrectomy with division of vagal branches (n = 14), and the patients with vagal nerve preserving gastrectomy (n = 12). RESULTS: There was no significant difference in serum levels of C-reactive protein, alpha-1-antirypsin, and interleukin-6 among the three groups. Also, postoperative maximum body temperature was similar. CONCLUSIONS: Vagotomy did not influence acute phase response after gastric cancer surgery. A multipathway mechanism for acute phase response including the induction of fever is suggested. 相似文献
153.
目的:通过对相同长度、宽度、不同厚度的Ti-6Al-7Nb合金铸件挠度的测量,观察铸件厚度与挠度的关系,为确定Ti-6Al-7Nb合金铸造义齿基托的适合厚度提供实验依据。方法:参照ISO关于义齿基托材料挠度的标准,测量不同厚度Ti-6Al-7Nb合金铸件的挠度,并与纯钛、Ti-6Al-4V合金及Co-Cr合金对比。结果:Ti-6Al-7Nb合金、纯钛及Ti-6Al-4V合金铸件的厚度在0.65mm时可以达到义齿基托挠度的标准;Co-Cr合金在0.57mm时可达到标准要求。结论:在临床制作Ti-6Al-7Nb合金义齿基托时,厚度应不低于0.65mm。 相似文献
154.
Claus Neurohr Patrick Huppmann Hanno Leuchte Martin Schwaiblmair Iris Bittmann Gundula Jaeger Rudolf Hatz Lorenz Frey Peter Überfuhr Bruno Reichart Jürgen Behr for the Munich Lung Transplant Group 《American journal of transplantation》2005,5(12):2982-2991
Bronchiolitis obliterans syndrome (BOS) is the limiting factor to long-term survival after lung transplantation. Previous studies suggested respiratory viral tract infections are associated with the development of BOS. To identify the impact of virus detection in bronchoalveolar lavage (BAL) fluid, we analyzed BAL samples from 87 consecutive lung transplant recipients for human herpesvirus (HHV)-6, Epstein-Barr virus, Herpes simplex virus 1/2, Cytomegalovirus, respiratory syncytical virus and adenovirus by PCR. Acute rejection, BOS and death were recorded for a mean follow-up time of 3.27 +/- 0.47 years. Results of PCR analysis and other potential risk factors were entered into a Cox regression analysis of BOS predictors and death. Only acute rejection was a distinct risk factor for BOS of all stages, death and death from BOS. HHV-6 was detected in 20 patients. Univariate and multivariate analysis revealed that HHV-6 was associated with an increased risk to develop BOS > orb = stage 1 and death, separate from the risk attributable to acute rejection. Identification of HHV-6 DNA in BAL fluid is a potential risk factor for BOS. Our results warrant further studies to elucidate a possible causal link between HHV-6 and BOS. 相似文献
155.
156.
Differential Cellular Gene Expression in Ganglioglioma 总被引:1,自引:0,他引:1
Uzma Samadani †Alexander R. Judkins ‡Albert Akpalu §Eleonora Aronica ¶Peter B. Crino 《Epilepsia》2007,48(1):646-653
Summary: Purpose: Gangliogliomas (GGs) are neuronal-glial tumors highly associated with epilepsy. We hypothesized that the expression of select gene families including neurotransmitter receptor subunits and growth factors would be distinct in neurons and astrocytes within GG compared with adjacent cortex and that these changes would yield insights into seizure onset and lesion formation.
Methods: Candidate gene expression was defined in single immunohistochemically labeled neurons and astrocytes microdissected from GG specimens compared with neurons and astrocytes microdissected from morphologically intact cortex adjacent to the GG or normal control cortex.
Results: Differential expression of 16 genes including glutamate transporter (EAAC1) and receptor (NMDA2C, mGluR5), growth factor (hepatocyte growth factor), and receptor (platelet derived growth factor receptor β, fibroblast growth factor receptor 3) mRNAs was detected in GG neurons compared with control neurons. In astrocytes, altered expression of p75NGF, mGluR3, TGFβ3 and Glt-1 mRNAs was detected. Nestin mRNA, a gene that exhibits enhanced expression in balloon cell cortical dysplasia, was increased in GG neurons. Because of the morphological similarities between GG and cortical dysplasia, we show that there is activation of the mTOR cascade in GG as evidenced by enhanced expression of phospho-p70S6kinase and phosphoribosomal S6 proteins.
Conclusion: We find differential candidate gene expression in neurons and astrocytes in GG compared with adjacent cortex and show that there is activation of the mTOR pathway. These changes highlight pathways that may be pivotal for epileptogenesis and lesion growth. 相似文献
Methods: Candidate gene expression was defined in single immunohistochemically labeled neurons and astrocytes microdissected from GG specimens compared with neurons and astrocytes microdissected from morphologically intact cortex adjacent to the GG or normal control cortex.
Results: Differential expression of 16 genes including glutamate transporter (EAAC1) and receptor (NMDA2C, mGluR5), growth factor (hepatocyte growth factor), and receptor (platelet derived growth factor receptor β, fibroblast growth factor receptor 3) mRNAs was detected in GG neurons compared with control neurons. In astrocytes, altered expression of p75NGF, mGluR3, TGFβ3 and Glt-1 mRNAs was detected. Nestin mRNA, a gene that exhibits enhanced expression in balloon cell cortical dysplasia, was increased in GG neurons. Because of the morphological similarities between GG and cortical dysplasia, we show that there is activation of the mTOR cascade in GG as evidenced by enhanced expression of phospho-p70S6kinase and phosphoribosomal S6 proteins.
Conclusion: We find differential candidate gene expression in neurons and astrocytes in GG compared with adjacent cortex and show that there is activation of the mTOR pathway. These changes highlight pathways that may be pivotal for epileptogenesis and lesion growth. 相似文献
157.
CD44v6和组织蛋白酶D表达与食管癌预后的关系 总被引:2,自引:0,他引:2
目的 研究CD4 4v6和组织蛋白酶D(cathepsinD ,CD)表达与食管癌生物学行为的关系。方法 应用免疫组化法 ,检测 6 5例食管鳞状细胞癌组织中CD4 4v6和CD表达水平。结果 在食管癌中CD4 4v6和CD表达阳性率分别为 5 8.5 %和 6 4 .6 %。CD4 4v6和CD表达均与肿瘤分级、浸润、淋巴结转移和预后相关。结论 CD4 4v6和CD异常表达与食管癌的病理生物学行为密切相关 ,可作为是预测食管癌转移潜能和评估食管癌预后的客观指标 相似文献
158.
Y. BÖTTIGER P. DOSTERT M. STROLIN BENEDETTI M. BANI F. FIORENTINI M. CASATI I. POGGESTI C. ALM G. ALVAN & L. BERTILSSON 《British journal of clinical pharmacology》1996,42(6):707-711
1 Nicergoline, an ergot derivative previously used as a vasodilator, has gained a new indication in treating the symptoms of senile dementia.
2 Nicergoline is rapidly hydrolysed to an alcohol derivative, 1-methyl-10-α-methoxy-9,10-dihydrolysergol (MMDL), which is further N -demethylated to form 10-α-methoxy-9,10-dihydrolysergol (MDL). A few individuals display aberrant metabolism of this drug, as shown by their diminished capacity to form the MDL metabolite. The aim of this study was to determine whether defective nicergoline metabolism is associated with the debrisoquine and/or the S-mephenytoin hydroxylation polymorphisms.
3 After a single, oral 30 mg dose of nicergoline, the plasma concentrations of its two metabolites were studied in 15 subjects, divided into three groups with respect to their debrisoquine and S-mephenytoin hydroxylation phenotypes.
4 The pharmacokinetic parameters of MMDL and MDL were similar in the ten subjects who were extensive metabolisers of debrisoquine (five of whom were poor metabolisers of S-mephenytoin) (mean MMDL Cmax 59 nmol l−1 and AUC (0, t h) 144 nmol l−1 h, mean MDL C max 183 nmol l−1 and AUC 2627 nmol l−1 h) but were markedly different from the five subjects who were poor metabolisers of debrisoquine (mean MMDL C max 356 nmol l−1 and AUC 10512 nmol l−1 h, MDL concentrations below limit of quantitation).
5 We conclude that the formation of MDL from MMDL in the metabolism of nicergoline is catalysed to a major extent by CYP2D6 and that the observed interindividual variation in the metabolic pattern of the drug is related to the debrisoquine hydroxylation polymorphism. 相似文献
2 Nicergoline is rapidly hydrolysed to an alcohol derivative, 1-methyl-10-α-methoxy-9,10-dihydrolysergol (MMDL), which is further N -demethylated to form 10-α-methoxy-9,10-dihydrolysergol (MDL). A few individuals display aberrant metabolism of this drug, as shown by their diminished capacity to form the MDL metabolite. The aim of this study was to determine whether defective nicergoline metabolism is associated with the debrisoquine and/or the S-mephenytoin hydroxylation polymorphisms.
3 After a single, oral 30 mg dose of nicergoline, the plasma concentrations of its two metabolites were studied in 15 subjects, divided into three groups with respect to their debrisoquine and S-mephenytoin hydroxylation phenotypes.
4 The pharmacokinetic parameters of MMDL and MDL were similar in the ten subjects who were extensive metabolisers of debrisoquine (five of whom were poor metabolisers of S-mephenytoin) (mean MMDL C
5 We conclude that the formation of MDL from MMDL in the metabolism of nicergoline is catalysed to a major extent by CYP2D6 and that the observed interindividual variation in the metabolic pattern of the drug is related to the debrisoquine hydroxylation polymorphism. 相似文献
159.
本文报告了2,4,6-三硝基甲苯(TNT)的代谢物,2-氨基-4,6-二硝基甲苯2和2,4-二氨基-6-硝基甲苯3的合成。以邻甲基苯甲酸为原料,经硝化(HNO_3-H_2SO_4)和Schmidt反应(NaN_3-H_2SO_4)得到2,用NaHS还原TNT的方法合成化合物3。 相似文献
160.
Low doses of the uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine (MK-801) induce locomotor stimulation in mice, whereas higher doses are associated with ataxia, stereotyped behaviors and catalepsy. We investigated the role of dopamine receptors and presynaptic dopamine neurons in the locomotor effects of dizocilpine. For comparison, we studied several other drugs that induce locomotor stimulation in mice. Pretreatment of male mice with haloperidol (0.1 mg/kg, i.p.) completely prevented the stimulation of normally coordinated locomotion induced by a non-intoxicating dose of dizocilpine (0.1 mg/kg, i.p.); haloperidol also attenuated the locomotor stimulation produced by phencyclidine (PCP, 1 and 2 mg/kg, i.p.), d-amphetamine (2 and 5 mg/kg, i.p.) and diazepam (0.5 mg/kg, i.p.). Haloperidol (doses up to 2.5 mg/kg) did not attenuate the ataxia and decreased locomotion induced by higher doses of dizocilpine (1 and 2 mg/kg). The active cis isomer of flupenthixol (0.5 mg/kg, i.p.), an antagonist of both D1 and D2 dopamine receptors, also diminished the stimulant actions of all of the test drugs, whereas its inactive trans form did not. The selective D1 antagonist R(±)-SCH 23390 (0.1 mg/kg) and the selective D2 antagonist raclopride (1 mg/kg) had little effect on the stimulatory effect of dizocilpine, although they did reduce the stimulation produced by PCP, d-amphetamine and diazepam. However, pretreatment with a combination of R(±)-SCH 23390 and raclopride completely prevented dizocilpine-induced locomotor stimulation. Pretreatment with α-methyl-p-tyrosine (AMPT, 50 and 250 mg/kg), an inhibitor of tyrosine hydroxylase, or with 6-hydroxydopamine (6-OH-DA, 50 μg, i.c.v.), a neurotoxin that destroys brain dopaminergic and noradrenergic neurons, did not attenuate the locomotor stimulation induced by dizocilpine, although these treatments did reduce the stimulant effects of d-amphetamine. In AMPT or 6-OH-DA pretreated mice, haloperidol (0.125 mg/kg) prevented the stimulatory effect of dizocilpine. These results support a role for dopamine receptors in the stimulation of normally coordinated locomotion by dizocilpine. However, the locomotor stimulant effect of dizocilpine, unlike that of d-amphetamine, can be expressed in the presence of D1 or D2 dopamine receptor blockade and does not appear to be dependent on intact presynaptic mechanisms. 相似文献