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   709篇
  免费   37篇
  国内免费   3篇
耳鼻咽喉   2篇
儿科学   44篇
妇产科学   11篇
基础医学   124篇
口腔科学   14篇
临床医学   52篇
内科学   126篇
皮肤病学   6篇
神经病学   88篇
特种医学   33篇
外科学   83篇
综合类   1篇
预防医学   52篇
眼科学   5篇
药学   35篇
肿瘤学   73篇
  2021年   11篇
  2020年   5篇
  2019年   10篇
  2018年   11篇
  2017年   9篇
  2016年   13篇
  2015年   16篇
  2014年   29篇
  2013年   26篇
  2012年   34篇
  2011年   36篇
  2010年   24篇
  2009年   28篇
  2008年   25篇
  2007年   33篇
  2006年   34篇
  2005年   38篇
  2004年   19篇
  2003年   16篇
  2002年   27篇
  2001年   10篇
  2000年   16篇
  1999年   14篇
  1998年   9篇
  1996年   5篇
  1995年   3篇
  1992年   11篇
  1991年   14篇
  1990年   13篇
  1989年   15篇
  1988年   13篇
  1987年   12篇
  1986年   13篇
  1985年   10篇
  1984年   8篇
  1983年   6篇
  1982年   6篇
  1980年   4篇
  1979年   7篇
  1978年   8篇
  1977年   8篇
  1976年   4篇
  1975年   8篇
  1974年   10篇
  1973年   10篇
  1972年   11篇
  1971年   7篇
  1970年   7篇
  1968年   3篇
  1967年   4篇
排序方式: 共有749条查询结果,搜索用时 15 毫秒
1.
A role for type II interferon (IFN-gamma) in resolving viral infection is suggested by the correlation of hepatitis C virus (HCV) clearance with enhancement of IFN-gamma-producing activated T cells in the resolution of acute HCV infection. Using vesicular stomatitis virus (VSV), a synergistic direct antiviral effect was documented using IFN-gamma1b and a potent, consensus type I IFN (IFN alfacon-1). Global expression profiling following EC50 exposure to IFN alfacon-1, IFN-gamma1b, or a cocktail of the two allowed the antiviral state to be correlated with induction of a subset of IFN-stimulated genes (ISGs). Genes identified through this analysis corresponded to classic antiviral components, ISGs more recently associated with direct antiviral functions, as well as expressed sequence tags (ESTs) and hypothetical proteins. The magnitude of these antiviral EC50-correlated expression events in human hepatoma (Huh7) cells exposed to clinically relevant doses of IFN alfacon-1, IFN-gamma1b, or a cocktail of the two was also probed because the standard of care for patients with chronic hepatitis C is type I IFN-containing regimens. Relative to type I IFNs used alone, the addition of type II IFN caused enhanced expression not only of many of the genes correlated with the direct antiviral state but also of genes involved in (1) antigen presentation to cytotoxic T lymphocytes (CTLs), (2) macrophage, natural killer (NK), and T helper 1 (Th1) cell recruitment and activation, (3) complement system function, (4) apoptosis, and (5) ISGs with unknown functions. As many of these processes are correlated clinically with resolution of chronic HCV infection, the combined use of these IFNs could display a beneficial effect on viral clearance in patients infected with HCV and other viruses through enhancement of one of these processes or of the direct antiviral state.  相似文献   
2.
The conceptual and methodological framework proposed by Doss (this issue) makes valuable suggestions for strategic choices in future research. This commentary addresses conceptual and terminological distinctions adopted by Doss, as well as his criticism of add-on/ dismantling studies. We also suggest research topics and methodological developments that could be integrated in Doss's framework to further expand understanding of therapeutic change.  相似文献   
3.
OBJECTIVE: Multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal-ganglionic degeneration (CBGD) are all clinically characterized by an akinetic-rigid syndrome together with a variety of additional signs. We hypothesised that these atypical parkinsonian syndromes (APS) will show distinctive patterns in their motor output upon transcranial magnetic stimulation (TMS) due to their different underlying anatomico-functional deficits. METHODS: We performed single and paired-pulse TMS and assessed inhibitory and excitatory response parameters from the first dorsal interosseus muscles in 13 patients with MSA, 18 with PSP, 13 with CBGD, 15 patients with Parkinson's disease and 17 healthy subjects. RESULTS: PSP and MSA patients had significantly enlarged response amplitudes at rest, reduced intracortical inhibition (ICI) and prolonged ipsi- and contralateral silent periods, whereas CBGD patients showed significantly increased motor thresholds, smaller response amplitudes at rest, shortened contralateral silent period, reduced transcallosal inhibition and a reduced ICI. In 22% of APS patients ipsilateral motor responses occurred in upper limb muscles irrespective of the underlying disease. CONCLUSIONS: Our results indicate that motor cortex disinhibition is predominant in patients with PSP and MSA. In CBGD more severe neuronal cell loss in the motor cortex itself may lead to hypoexcitability of corticospinal and transcallosal pathways.  相似文献   
4.
To assist in the selection of a preferable vitamin A deficiency control policy, a model has been developed to organize information on program costs and program-related effects. The model was designed to compare three approaches: (1) diet modification; (2) fortification of processed foods; and (3) periodic large doses. Health effects projected are rates of specific eye pathologies associated with vitamin A deficiency (xerophthalmia), and mortalities within age cohorts. Effectiveness is calculated as a function of coverage, biological efficacy, and incidence of vitamin A deficiency. The model was applied to data from the Province of West Java in Indonesia. The results of this application suggest that funding level considerations are an important factor in selecting a preferred control strategy. In addition to determining the relative resource requirements of alternative interventions aimed at reducing the morbidity and mortality effects of vitamin A deficiencies, the model, using marginal cost and marginal effectiveness information, can serve as a guide to the most efficient allocation of resources for each type of intervention.  相似文献   
5.
Interpersonal behavior is assumed to be motivated by personal goals that an individual develops ontogenetically to satisfy and protect psychological needs. Interpersonal problems are hypothesized to (1) occur as a consequence of strong avoidance goals and (2) lead to decreased satisfaction of the person's approach goals. The hypotheses are tested using the self‐report data of 284 subjects with predominantly anxiety, affective and eating disorders who applied for treatment in a clinic offering inpatient cognitive–behavioral psychotherapy. Results indicate that interpersonal problems mediate the relationship between avoidance goals and the satisfaction of approach goals. Additional analyses explore specific associations between avoidance goals and certain kinds of interpersonal problem. Avoidance goals are then located within the interpersonal circle structure. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
6.
Zum Thema Medikamente, die in hormonelle Regelkreise eingreifen, werden wegen ihrer hohen Wirksamkeit und guten Vertr?glichkeit bei hormonsensitiven Tumoren wie Mamma-, Prostata- und dem Endometriumkarzinom eingesetzt. Ziel aller hormonellen Behandlungsma?nahmen ist die Ausschaltung der hormonbedingten Wachstumsstimulation durch Blockade der Hormonproduktion oder Hemmung der Hormonwirkung auf zellul?rer Ebene. Dies erfolgt bei postmenopausalen Frauen mit Brustkrebs durch Aromatasehemmstoffe, bei pr?menopausalen, ebenso wie bei Patienten mit Prostatakarzinom durch GnRH-Analoga. Eine neue Generation von Aromatasehemmstoffen zur Behandlung des Brustkrebses weist nicht nur bessere Vertr?glichkeit und Wirksamkeit auf, sondern bedeutet auch einen überlebensvorteil für die Patientinnen. Anti?strogene sind bei pr?- und insbesondere bei postmenopausalen Patientinnen sowohl in der adjuvanten, als auch in der palliativen Behandlungssituation wirksam. Aufgrund ihrer guten Vertr?glichkeit wurden sie bei Frauen mit erh?htem Brustkrebsrisiko mit Erfolg zur Pr?vention eingesetzt. Bei Patienten mit Prostatakarzinom hat die sog. komplette Androgenblockade (chirurgische oder medikament?se Ausschaltung der Testesfunktion und gleichzeitige Antiandrogengabe) die Hoffnung auf bessere Krankheitskontrolle nicht erfüllen k?nnen.  相似文献   
7.
Free electron lasers (FELs) allow the generation of electromagnetic radiation (EM) in a wide field of frequencies (respectively wavelengths) through the proper adjustment of the energy of an electron beam and the field configuration of a magnetic undulator passed by this beam. Terahertz (THz) radiation covers the region of the electromagnetic spectrum between approximately 0.3 and 30 THz and thus can be considered a continuation of the optical spectrum beyond the far infrared (IR). The very interesting results obtained from various studies of the interaction between IR radiation and biomolecules or tissue have stimulated increasing interest in the study of biological systems using THz radiation. This paper points out what role modern FELs can play in this research.  相似文献   
8.
The identification of specific genetic loci that contribute to inflammatory and autoimmune diseases has proved difficult due to the contribution of multiple interacting genes, the inherent genetic heterogeneity present in human populations, and a lack of new mouse mutants. By using N-ethyl-N-nitrosourea (ENU) mutagenesis to discover new immune regulators, we identified a point mutation in the murine phospholipase Cg2 (Plcg2) gene that leads to severe spontaneous inflammation and autoimmunity. The disease is composed of an autoimmune component mediated by autoantibody immune complexes and B and T cell independent inflammation. The underlying mechanism is a gain-of-function mutation in Plcg2, which leads to hyperreactive external calcium entry in B cells and expansion of innate inflammatory cells. This mutant identifies Plcg2 as a key regulator in an autoimmune and inflammatory disease mediated by B cells and non-B, non-T haematopoietic cells and emphasizes that by distinct genetic modulation, a single point mutation can lead to a complex immunological phenotype.  相似文献   
9.
The interceptive activity of 2 new synthesized steroid compounds: STS 153 (17 beta-Phenylaminocarbonyloxy-estra-1,3,5(10)-triene-3-methyl ether and STS 287 (16 alpha-Bromo-17 beta-[N',N'-dimethylhydrazino]-carbonyloxy-estra-1,3,5(10)-triene-3-methyl ether) and of 17 alpha-Ethynylestradiol was investigated in baboons.--Postcoital oral administration of 1--3 mg/kg b. w. STS 153 for 5--7 days and of 1 mg/kg b. w. STS 287 for 5 days resulted in a fertility inhibition of about 90% and 95% respectively. A dose of 2 mg/kg b. w. of ethynylestradiol was necessary to attain complete fertility inhibition. Following administration of STS 153 and STS 287, side effects were not observed. Pharmacokinetic aspects are discussed.  相似文献   
10.
Vasoconstrictor and pilomotor fibres in skin nerves to the cat's tail   总被引:1,自引:0,他引:1  
Summary Postganglionic neurones to the tail's skin of the cat were investigated with regard to their spontaneous activity, response characteristics to somatic stimuli and asphyxia, the conduction velocity of their axons, and the conduction velocity of the preganglionic axons converging on them. The cats were anaesthetized with chloralose, immobilized, and arteficially ventilated. With this regimen the postganglionic neurones were divided into two types: 1. Type 1 neurones are spontaneously active and exhibit reflexes upon somatic stimulation. During asphyxia they are mostly first depressed and then excited for about 2–3 min. Their axons conduct with 0.57±0.13 m/s (mean ± SD). The preganglionic axons converging on them conduct with 5.4±1.6 m/s. 2. Type 2 neurones are not spontaneously active and exhibit with few exceptions no reflexes on somatic stimuli. During asphyxia they are activated after 3–4 min, concomitantly with piloerection, when the activity in type 1 neurones is already decreasing. Their axons conduct with 0.84±0.14 m/s, the preganglionic axons converging on them conduct with 9.9±2.9 m/s. 3. From these characteristics it is concluded that type 1 neurones have vasomotor function and most type 2 neurones pilomotor function.  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