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   15717篇
  免费   1152篇
  国内免费   603篇
耳鼻咽喉   35篇
儿科学   77篇
妇产科学   44篇
基础医学   1583篇
口腔科学   325篇
临床医学   803篇
内科学   1572篇
皮肤病学   94篇
神经病学   1451篇
特种医学   191篇
外国民族医学   1篇
外科学   834篇
综合类   1564篇
现状与发展   1篇
预防医学   291篇
眼科学   118篇
药学   6838篇
中国医学   1489篇
肿瘤学   161篇
  2023年   127篇
  2022年   267篇
  2021年   440篇
  2020年   340篇
  2019年   374篇
  2018年   429篇
  2017年   398篇
  2016年   434篇
  2015年   450篇
  2014年   833篇
  2013年   1448篇
  2012年   829篇
  2011年   875篇
  2010年   638篇
  2009年   685篇
  2008年   703篇
  2007年   750篇
  2006年   587篇
  2005年   585篇
  2004年   439篇
  2003年   474篇
  2002年   388篇
  2001年   340篇
  2000年   342篇
  1999年   301篇
  1998年   289篇
  1997年   290篇
  1996年   254篇
  1995年   242篇
  1994年   232篇
  1993年   224篇
  1992年   213篇
  1991年   184篇
  1990年   201篇
  1989年   177篇
  1988年   150篇
  1987年   131篇
  1986年   153篇
  1985年   164篇
  1984年   164篇
  1983年   131篇
  1982年   161篇
  1981年   142篇
  1980年   109篇
  1979年   81篇
  1978年   74篇
  1977年   49篇
  1976年   51篇
  1975年   27篇
  1974年   26篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
扶正固本法对青少年哮喘患者基因表达的影响   总被引:1,自引:0,他引:1  
目的 研究复方中药敏康片治疗青少年哮喘的疗效和作用机理。方法 选择20例青少年哮喘患者进行治疗,另设青少年特应性皮炎患者组(20例)和青少年正常组(19例)为对照。哮喘组和皮炎组口服敏康片,疗程为6个月,观察疗效、血清总IgE及FcεRIβ、IL-4Rα基因表达改变情况。结果 哮喘组显效6例,有效12例,无效2例,总有效率90%;皮炎组显效4例,有效13例,无效3例,总有效率85%;哮喘组IgE治疗前后有显著差异(P〈0.01)。皮炎组IgE治疗前后有差异(P〈0.05);用Northern blot法检测FctRlt3、IL-4Rα基因,IL-4Rα吸光度值两组治疗前均较正常组高,哮喘组治疗后降低。FcεRIβ吸光度值两组治疗前均较正常组高,治疗后均降低。结论 复方中药可以调整青少年哮喘患者相关基因表达,改善患者过敏状态,缓解临床症状。  相似文献   
12.
Background and Aim: This study investigated the clinical features of hepatocellular carcinoma in patients with sustained virological response to interferon for hepatitis C viral (HCV) infection. Methods: A total of 7715 patients with HCV infection were treated with interferon and followed up for more than 1 year after withdrawal of interferon in 64 Japanese hospitals and clinics between July 1988 and August 2001. Sustained virological response was obtained in 2515 (32.6%) patients. Of these 2515 patients, clinical data were collected for 38 patients in whom hepatocellular carcinoma developed. Sustained virological response was defined as HCV RNA negativity more than 6 months after the termination of interferon. Results: All patients were HCV RNA negative at the time of diagnosis of hepatocellular carcinoma. The median period until the detection of hepatocellular carcinoma was 4.7 years (range 1.4–9.0 years). There were significant improvements in hepatic function including serum albumin, aspartate aminotransferase, alanine aminotransferase, indocyanine green test, platelet count and histological activity grade in comparison with those before interferon therapy and at the onset of hepatocellular carcinoma. The maximum tumor size in patients without medical follow‐up for 1 year or more (median: 60 mm) was significantly larger than in patients who were periodically followed up for 6 months or less (median: 25 mm) (P = 0.002). Conclusions: The present findings emphasize the importance of regular medical follow up of patients with HCV infection, as even patients showing a sustained virological response to interferon and in whom hepatic function has improved have the potential to develop hepatocellular carcinoma.  相似文献   
13.
Neurotransmitter- or neuromodulator-like actions ofl-DOPA were investigated with intracellular recordings from submucous plexus neurons of the guinea-pig caecum.l-DOPA at 30 nM augmented the amplitude of fast EPSPs, but did not affect depolarizations elicited by puff application of acetylcholine (ACh). The augmenting effect ofl-DOPA on the fast EPSPs was counteracted byl-DOPA methyl ester. The fast EPSPs were depressed by 10 μMl-DOPA, but transiently augmented after rinsing the drug.l-DOPA methyl ester did not affect the inhibitory action ofl-DOPA on the fast EPSPs, but antagonized the potentiation following the inhibition. The depolarization elicited by exogenously applied. ACh was inhibited by 10 μMl-DOPA. Intracellular Ca2+ concentrations ([Ca2+]i) of the neuronal soma were measured with fura-2 microfluorophotometry. The transient increase in the [Ca2+]i evoked by the somatic action potential (Δ[Ca2+]AP) was facilitated by 30 nMl-DOPA, but decreased by the drug at 10 μM. It is concluded thatl-DOPA at low concentrations enhances the Δ[Ca2+]AP, increasing the neurotransmitter release, but at high dose diminishes the Δ[Ca2+]AP, inhibiting the neurotransmission.  相似文献   
14.
医药行业科技成果产业化与其他行业科技成果转化相比具有更高的风险,转化能力也是最低的,因此,对其从事前、事中、事后三方面加强风险控制具有重要的观实意义。  相似文献   
15.
马来酸罗格列酮胃漂浮型缓释片的研究   总被引:10,自引:0,他引:10       下载免费PDF全文
目的:根据流体动力学平衡控释原理(HBS)研制了马来酸罗列酮胃漂浮型缓释片。方法;以体外释放度和漂浮情况为筛选指标,采用单因素考察和正交试验设计相结合, 对胃漂浮缓释片的处方、制备工艺及体外释放条件进行优化筛选;采用γ闪烁照相技术对优化处方的内漂浮情况进行胃内动态观察。结果:马来酸罗格列酮胃漂浮缓释片在释放介质中迅速起漂,持漂时间超过12h,12h达最大累积释放;初步确定在胃内滞留时间达3h以上。结论:优化处方的释放过程符合Higuchi方程,释放机制为异常扩散;胃漂浮片在胃滞时间明显长于普通片。  相似文献   
16.
Summary Resistant club foot remains an unsolved problem because of the complex aetiological and pathological factors, and is still seen quite frequently, especially in developing countries. The posteromedial skin contracture is a potent deforming force which is responsible for many failures or relapses. I report the results of an operation in which a rotation skin flap was combined with an extensive soft-tissue release. The age of the children was from 9 months to 10 years. The follow-up period was from one to 9 years with an average of 43 months, and in 50 cases for more than 5 years. I consider that the outcome has been excellent or good in 94 out of 100 feet.
Résumé Le pied bot invétéré demeure un problème mal résolu en raison de la complexité des facteurs étiologiques et anatomiques et il est encore bien souvent rencontré, notamment dans les pays en voie de développement. La rétraction cutanée postéro-interne représente un puissant élément de la déformation, qui est responsable de bon nombre d'échecs ou de récidives. Nous rapportons les résultats d'une opération qui associe un lambeau cutané de rotation à la libération des parties molles. L'âge des enfants était compris entre neuf mois et dix ans. Le recul est de un à neuf ans, avec une moyenne de 43 mois. Cinquante enfants ont été suivis plus de cinq ans. Les résultats sont excellents ou bons dans 94% des cas.
  相似文献   
17.
18.
BACKGROUND: Results from several studies indicate that the magnitude of immediate symptoms of type I allergy caused by allergen-induced cross-linking of high-affinity Fc epsilon receptors on effector cells (mast cells and basophils) is not always associated with allergen-specific IgE levels. OBJECTIVE: To investigate the association of results from intradermal skin testing, basophil histamine release and allergen-specific IgE, IgG1-4, IgA and IgM antibody levels in a clinical study performed in birch pollen-allergic patients (n = 18). METHODS: rBet v 1-specific IgEs were measured by quantitative CAP measurements and by using purified Fc epsilon RI-derived alpha-chain to quantify IgE capable of binding to effector cells. Bet v 1-specific IgG subclasses, IgA and IgM levels were measured by ELISA, and basophil histamine release was determined in whole blood samples. Intradermal skin testing was performed with the end-point titration method. RESULTS: Our study demonstrates on the molecular level that the concentrations of allergen-specific IgE antibodies capable of binding to Fc epsilon RI and biological sensitivities are not necessarily associated. A moderate association was found between cutaneous and basophil sensitivity. CONCLUSION: Our results highlight the quantitative discrepancies and limitations of the present diagnostic tools in allergy, even when using a single allergenic molecule. The quantity of allergen-specific serum IgE is only one component of far more complex cellular systems (i.e. basophil-based tests, skin tests) used as indirect diagnostic tests for IgE-mediated allergic sensitivity.  相似文献   
19.
The mechanism of release from sustained-release adinazolam mesylate tablets was assessed by the Higuchi equation and by analysis of drug release profiles through 60% released using the Peppas equation. Computed values of the diffusional exponent, n, ranged from 0.59 to 0.66. Values of n in this range are consistent with a mixed mechanism of release, with diffusion of drug through the hydrated polymer matrix and relaxation of this matrix being the principal processes controlling release. The rate of in vitro drug release was increased for half tablets relative to whole tablets and is attributed to an increase in the surface to volume ratio of half tablets of about 16%. This increase in surface-to-volume ratio of half tablets was reflected by an increase in the constant, k, from the Peppas equation of 20–23% and by an increase in the slope of Higuchi plots of 12–18% for four lots of tablets. In vivo/in vitro relationships from two bioavailability studies were thoroughly evaluated. Using either a linear or a quadratic relationship, an in vivo/in vitro correlation exists for sustained-release adinazolam mesylate tablets.  相似文献   
20.
In vivo electrochemical methods were employed to study the potassium (K+-evoked release of monoamines from the cerebellum of the chloral hydrate anesthetized rat. K+-evoked releases were elicited using micropipette-Nafion-coated graphite epoxy electrode arrays in the granule/Purkenje cell layer, molecular layer, and white matter. These recorded releases were generally found to be reversible, moderately dose-dependent, and reproducible. However, the temporal dynamics of the releases were different for the cell layer versus molecular layer records. Releases were infrequently observed in cerebellar white matter, an area which is relatively devoid of monoamine containing terminals. The signals recorded from the cell and molecular layers were significantly attenuated by pretreatment with nomifensine, a potent catecholamine reuptake blocker, significantly prolonged the K+-evoked signals observed in both the granule/Purkenje cell and molecular layers. These data, taken together with earlier reports on the electrophysiological responses to activation of cerebellar noradrenergic inputs, support the conjecture that in vivo electrochemical recording methods have the sensitivity and spatial resolution for studies of functional monoamine release from brain regions that have a diffuse or laminated monoamine innervation.  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