全文获取类型
收费全文 | 5321篇 |
免费 | 302篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 109篇 |
儿科学 | 94篇 |
妇产科学 | 135篇 |
基础医学 | 948篇 |
口腔科学 | 96篇 |
临床医学 | 453篇 |
内科学 | 1009篇 |
皮肤病学 | 116篇 |
神经病学 | 713篇 |
特种医学 | 289篇 |
外科学 | 618篇 |
综合类 | 31篇 |
一般理论 | 3篇 |
预防医学 | 295篇 |
眼科学 | 97篇 |
药学 | 351篇 |
中国医学 | 4篇 |
肿瘤学 | 282篇 |
出版年
2023年 | 27篇 |
2022年 | 53篇 |
2021年 | 134篇 |
2020年 | 54篇 |
2019年 | 82篇 |
2018年 | 119篇 |
2017年 | 76篇 |
2016年 | 102篇 |
2015年 | 133篇 |
2014年 | 142篇 |
2013年 | 170篇 |
2012年 | 316篇 |
2011年 | 378篇 |
2010年 | 184篇 |
2009年 | 192篇 |
2008年 | 316篇 |
2007年 | 277篇 |
2006年 | 285篇 |
2005年 | 248篇 |
2004年 | 222篇 |
2003年 | 210篇 |
2002年 | 192篇 |
2001年 | 111篇 |
2000年 | 87篇 |
1999年 | 92篇 |
1998年 | 51篇 |
1997年 | 38篇 |
1996年 | 33篇 |
1995年 | 28篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 59篇 |
1991年 | 60篇 |
1990年 | 51篇 |
1989年 | 33篇 |
1988年 | 31篇 |
1987年 | 36篇 |
1986年 | 34篇 |
1985年 | 31篇 |
1984年 | 25篇 |
1983年 | 26篇 |
1979年 | 32篇 |
1978年 | 22篇 |
1976年 | 21篇 |
1975年 | 25篇 |
1974年 | 27篇 |
1973年 | 22篇 |
1972年 | 41篇 |
1971年 | 25篇 |
1932年 | 22篇 |
排序方式: 共有5643条查询结果,搜索用时 15 毫秒
51.
52.
David N Pham Hong Wei Chu Richard J Martin Monica Kraft 《Annals of allergy, asthma & immunology》2003,90(1):72-78
BACKGROUND: Matrix metalloproteinase-9 (MMP-9) is capable of degrading elastin, whereas tissue inhibitor of metalloproteinase-1 (TIMP-1) can inhibit MMP-9 activity. We observed reduced airway tissue elastin volume density in six subjects with nocturnal asthma (NA) as compared with seven subjects with nonnocturnal asthma (NNA) and seven normal controls (NL) when endobronchial biopsies were evaluated morphometrically at 4:00 PM and 4:00 AM. OBJECTIVE: We hypothesized that increased metalloproteinases and decreased tissue inhibitors of metalloproteinases in the airways of subjects with NA may be responsible for reduced elastin volume density. METHODS: Ten additional subjects with NA, 10 subjects with NNA, and 7 normal control subjects underwent bronchoscopy with bronchoalveolar lavage at 4:00 PM and 4:00 AM. Levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 were determined in bronchoalveolar lavage by enzyme-linked immunosorbent assay. RESULTS: There was a fourfold circadian increase in bronchoalveolar lavage levels of MMP-9, and there was a twofold increase in MMP-9:TIMP-1 ratio in NA subjects from 4:00 PM to 4:00 AM. There were no circadian changes in the NNA and NL subjects. At 4:00 AM, MMP-9 levels and the MMP-9:TIMP-1 ratio were highest in NA subjects. At 4:00 PM, no significant group differences were observed. The MMP-9 levels positively correlated with the overnight fall in forced expiratory volume in 1 second and the MMP-9/TIMP-1 ratio negatively correlated with the 4:00 AM % predicted forced expiratory volume in 1 second. CONCLUSIONS: Our results from these two pilot studies suggest that increased MMP-9 and decreased TIMP-1 at night in NA may lead to reduced elastin density. 相似文献
53.
Jaume Alijotas-Reig Manel Casellas-Caro Raquel Ferrer-Oliveras Elisa Llurba-Olive Eduard Hermosilla Miquel Vilardell-Tarres Lluis Cabero-Roura 《American journal of reproductive immunology (New York, N.Y. : 1989)》2008,60(3):229-237
Problem Anti-beta2 -Glicoprotein-1 antibodies (anti-β2 GPI-ab) have been related to recurrent miscarriage (RM) with conflicting results. The aim was to evaluate the role of anti-β2 -GPI-ab as unique biological marker in RM related to antiphospholipid (aPL).
Method of study A cohort study that included 59 cases, divided in two groups, was designed: group 1 comprised 43 pregnant women with 'obstetric' antiphospholipid syndrome (APS) and group 2 included 16 cases with similar complaints but only having repeatedly anti-β2 -GPI-ab. Previous thrombosis and/or inherited thrombophilia were excluded. Lupus anticoagulant, anticardiolipin antibodies (aCA), anti-β2 -GPI-ab, and other autoantibodies were analyzed. Miscarriages, premature births, pre-eclampsia, live births, placental and systemic thromboses were studied.
Results No differences in previous obstetric complications were detected ( P = 1.00–0.164). After the treatment, differences in number of obstetric complications were not seen ( P = 1.00). Live births were similar in two groups (88.4% and 93.7%; P = 1.00). Placental thrombosis was equal in both groups, 93.3% versus 80% ( P = 1.00).
Conclusion These results suggest that anti-β2 -GPI-ab may be considered a biological marker for obstetric APS. 相似文献
Method of study A cohort study that included 59 cases, divided in two groups, was designed: group 1 comprised 43 pregnant women with 'obstetric' antiphospholipid syndrome (APS) and group 2 included 16 cases with similar complaints but only having repeatedly anti-β
Results No differences in previous obstetric complications were detected ( P = 1.00–0.164). After the treatment, differences in number of obstetric complications were not seen ( P = 1.00). Live births were similar in two groups (88.4% and 93.7%; P = 1.00). Placental thrombosis was equal in both groups, 93.3% versus 80% ( P = 1.00).
Conclusion These results suggest that anti-β
54.
Thomas Läubli Hans Mion Eduard Senn Carlo Thomas und Hans Zeier 《Sozial- und Pr?ventivmedizin》1985,30(4-5):278-279
Summary In 12 groups of office work questionnaire results reveal a high prevalence of backpains. A high keying rate is combined with increased armpains. An index postural discomfort is related to working conditions, work satisfaction, personality and others. In the group of flight reservation a longer stay in this department is combined with increased postural complaints. Movable keyboards are preferable to built-in ones.
Douleurs rheumatiques dans les employéé de bureau
Résumé Les résultats d'une interrogation par un questionnaire dans 12 collectifs d'employés de bureau montrent, que les douleurs dans le dos sont fréquentes. De plus, la prévalence des douleurs dans le bras est augmentée, lorsque le nombre de frappe est élevé. Un index Douleurs Rheumatique est correlé avec les examins de palpations, les conditions du travail, la satisfaction au travail, la personalité et avec d'autres facteurs. Dans le groupe Flugreservation la durée d'emploi est correlée avec la frequence des douleurs. Les claviers mobiles sont plus avantageux que des claviers fixes.相似文献
55.
Martin Dosedl Eduard Jirkovský Kateina Mackov Lenka Kujovsk Kr
mov Lenka Javorsk Jana Pourov Laura Mercolini Fernando Remio Lucie Novkov Pemysl Mladnka 《Nutrients》2021,13(2)
Vitamin C (L-ascorbic acid) has been known as an antioxidant for most people. However, its physiological role is much larger and encompasses very different processes ranging from facilitation of iron absorption through involvement in hormones and carnitine synthesis for important roles in epigenetic processes. Contrarily, high doses act as a pro-oxidant than an anti-oxidant. This may also be the reason why plasma levels are meticulously regulated on the level of absorption and excretion in the kidney. Interestingly, most cells contain vitamin C in millimolar concentrations, which is much higher than its plasma concentrations, and compared to other vitamins. The role of vitamin C is well demonstrated by miscellaneous symptoms of its absence—scurvy. The only clinically well-documented indication for vitamin C is scurvy. The effects of vitamin C administration on cancer, cardiovascular diseases, and infections are rather minor or even debatable in the general population. Vitamin C is relatively safe, but caution should be given to the administration of high doses, which can cause overt side effects in some susceptible patients (e.g., oxalate renal stones). Lastly, analytical methods for its determination with advantages and pitfalls are also discussed in this review. 相似文献
56.
A low molecular weight allergen of white birch (Betula verrucosa) is highly homologous to human profilin 总被引:1,自引:0,他引:1
R Valenta M Duchêne M Breitenbach K Pettenburger L Koller H Rumpold O Scheiner D Kraft 《International archives of allergy and applied immunology》1991,94(1-4):368-370
Cloning of allergens has contributed substantially to the understanding of mechanisms in allergic diseases by providing information about the sequence and hence biological functions of allergens. The major birch pollen allergen, Bet v I [Breiteneder H, et al: EMBO J 1989;8:1935-1938] and the white-faced hornet venom allergen (antigen 5) [Si Yun Fang K, et al: Proc. Natl. Acad. Sc. USA 1988;85:895-899] were shown to be highly homologous to pathogenesis-related proteins of plants. In the case of the major allergen of house dust mite, Der p I, homology to proteases was demonstrated. Therefore, the proposed biological function of these IgE-binding proteins might be related to their allergenic potential. In this paper we tentatively identify a ubiquitous family of low molecular weight allergens as profilins. The identification is based on a sequence homology, (b) binding to poly(L-proline), and (c) immunological cross-reactivity. Recombinant birch profilin was purified to homogeneity and showed the same properties as natural profilins. 相似文献
57.
Needle biopsy of renal allografts: comparison of two techniques 总被引:2,自引:0,他引:2
Bogan ML; Kopecky KK; Kraft JL; Holladay AO; Filo RS; Leapman SB; Thomalla JV 《Radiology》1990,174(1):273-275
Two techniques for renal allograft biopsy were retrospectively evaluated to compare relative safety and efficacy. After ultrasound (US) localization of the kidney and biopsy with a hand-held 14-gauge cutting needle, an adequate specimen was obtained in 74 of 77 cases (96%). Major complications occurred in six of these 77 cases (8%). One hundred four biopsies were performed by using a smaller 18-gauge cutting needle with a spring-loaded biopsy "gun" and real-time US guidance. With this newer technique, specimens adequate for diagnosis were obtained in 99 biopsies (95%). There was a single major complication with this technique (1%). The 18-gauge needle with real-time US guidance yields comparably adequate specimens with a lower frequency of complications. 相似文献
58.
Wenjie Bi Anke Kraft Sophie Engelskircher Jasmin Mischke Moana Witte Frank Klawonn Marco van Ham Markus Cornberg Heiner Wedemeyer Julia Hengst Lothar Jänsch 《European journal of immunology》2023,53(11):2250291
Chronic hepatitis C virus (HCV) infections compromise natural killer (NK)-cell immunity. Direct-acting antivirals (DAA) effectively eliminate HCV, but the long-term effects on NK cells in cured patients are debated. We conducted a proteomic study on CD56+ NK cells of chronic HCV-infected patients before and 1 year after DAA therapy. Donor-variation was observed in NK-cell proteomes of HCV-infected patients, with 46 dysregulated proteins restored after DAA therapy. However, 30% of the CD56+ NK-cell proteome remained altered 1 year post-therapy, indicating a phenotypic shift with low donor-variation. NK cells from virus-negative cured patients exhibited global regulation of RNA-processing and pathways related to “stimuli response”, “chemokine signaling”, and “cytotoxicity regulation”. Proteomics identified downregulation of vesicle transport components (CD107a, COPI/II complexes) and altered receptor expression profiles, indicating an inhibited NK-cell phenotype. Yet, activated NK cells from HCV patients before and after therapy effectively upregulated IFN-γ and recruited CD107a. Conversely, reduced surface expression levels of Tim-3 and 2B4 were observed before and after therapy. In conclusion, this study reveals long-term effects on the CD56+ NK-cell compartment in convalescent HCV patients 1 year after therapy, with limited abundance of vesicle transport complexes and surface receptors, associated with a responsive NK-cell phenotype. 相似文献
59.
Magnetic resonance spectroscopy allows neurochemistry to be probed noninvasively in vivo. Recent advances in our understanding of the biochemical significance of the various neurochemicals that are observable allow a variety of pathologic states of relevance to encephalopathies and neurodegenerative disorders to be observed. Measurements of brain glutamate and glutamine allow observation of neuronal/glial substrate cycling and ammonia detoxification. Myo-inositol allows changes in cerebral osmolarity and gliosis to be observed. N-acetylaspartate is a marker of neuronal health and number. Lactate allows nonoxidative glycolysis to be observed. These molecules are now being used to ask etiologic questions that are of relevance to encephalopathies and neurodegeneration, as well to probe longitudinally both natural history and therapeutic interventions in these conditions. Combined with recent advances in anatomic magnetic resonance imaging as well as perfusion magnetic resonance imaging, magnetic resonance spectroscopy has the potential to aid greatly in our understanding of neuronal dysfunction in a wide variety of neurologic pathologies, even in single patients. 相似文献
60.
Arens S Kraft C Schlegel U Printzen G Perren SM Hansis M 《Archives of orthopaedic and trauma surgery》1999,119(1-2):82-85
Resistance to local infection after fracture fixation with plate osteosynthesis may be influenced by the implantation technique.
It is known that the extent of the surgical approach to the bone can compromise the local defence capacity. We have investigated
susceptibility to infection after a local bacterial challenge in rabbit tibiae using either the open surgical approach for
‘biological’ internal fixation of standard 2.0 dynamic compression plates or the method of minimally invasive plate osteosynthesis
(MIPO), a percutaneous, tunnelling insertion technique preserving the integrity of the overlying soft tissue. After the wounds
had been closed, various concentrations of Staphylococcus aureus were injected in the direct vicinity of the implants. The infection rate for the open surgical technique was 38.5% and that
for the MIPO technique, 25%. This difference is not statistically significant (P > 0.05) suggesting that resistance to local infection associated with the MIPO method is at least equivalent to the open
approach for plate osteosynthesis.
Received: 22 January 1998 相似文献