全文获取类型
收费全文 | 38667篇 |
免费 | 2318篇 |
国内免费 | 123篇 |
专业分类
耳鼻咽喉 | 549篇 |
儿科学 | 1375篇 |
妇产科学 | 821篇 |
基础医学 | 5463篇 |
口腔科学 | 870篇 |
临床医学 | 3077篇 |
内科学 | 8859篇 |
皮肤病学 | 1143篇 |
神经病学 | 3384篇 |
特种医学 | 923篇 |
外科学 | 4572篇 |
综合类 | 233篇 |
一般理论 | 32篇 |
预防医学 | 3769篇 |
眼科学 | 721篇 |
药学 | 2175篇 |
中国医学 | 117篇 |
肿瘤学 | 3025篇 |
出版年
2023年 | 249篇 |
2022年 | 324篇 |
2021年 | 960篇 |
2020年 | 588篇 |
2019年 | 1006篇 |
2018年 | 1363篇 |
2017年 | 920篇 |
2016年 | 941篇 |
2015年 | 1057篇 |
2014年 | 1253篇 |
2013年 | 1832篇 |
2012年 | 2806篇 |
2011年 | 2949篇 |
2010年 | 1599篇 |
2009年 | 1319篇 |
2008年 | 2517篇 |
2007年 | 2545篇 |
2006年 | 2386篇 |
2005年 | 2342篇 |
2004年 | 2123篇 |
2003年 | 1971篇 |
2002年 | 1878篇 |
2001年 | 831篇 |
2000年 | 944篇 |
1999年 | 672篇 |
1998年 | 252篇 |
1997年 | 197篇 |
1996年 | 184篇 |
1995年 | 159篇 |
1994年 | 145篇 |
1993年 | 130篇 |
1992年 | 250篇 |
1991年 | 262篇 |
1990年 | 207篇 |
1989年 | 173篇 |
1988年 | 129篇 |
1987年 | 159篇 |
1986年 | 142篇 |
1985年 | 150篇 |
1984年 | 96篇 |
1983年 | 94篇 |
1982年 | 93篇 |
1981年 | 68篇 |
1980年 | 60篇 |
1979年 | 74篇 |
1978年 | 58篇 |
1976年 | 49篇 |
1974年 | 62篇 |
1973年 | 44篇 |
1970年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
101.
Eva Maria Roes Maarten T M Raijmakers Wilbert H M Peters Eric A P Steegers 《Clinical chemistry and laboratory medicine》2002,40(5):496-498
Oral N-acetylcysteine supplementation in nine young healthy females induced a quick and highly significant decrease in plasma homocysteine levels and an increase in whole blood concentration of the antioxidant glutathione. N-acetylcysteine impresses as an efficient drug in lowering homocysteine concentration and might be beneficial for individuals with hyperhomocysteinemia who are at increased risk of cardiovascular disease. 相似文献
102.
Mari-Ann Flyvholm Barbara M. Hall Tove Agner Eva Tiedemann Peter Greenhill Walter Vanderveken Fred E. Freeberg Torkil Menné 《Contact dermatitis》1997,36(1):26-33
Our purpose was to investigate the eliciting threshold concentration of formaldehyde in formaldehyde-sensitive individuals in the occluded and non-occluded patch teat and to evaluate the relationship in repeated open application test (ROAT) with a product containing a formaldehyde releaser. 20 formaldehyde-sensitive patients and a control group of 20 healthy volunteer were included in the study. Occluded and non-occluded patch tests with formaldehyde solutions form 25 to 10,000 ppm. and ROAT for I week with a leave-on cosmetic product containing on average 300 ppm formaldehyde. Were carried out simultaneously on each subject. In the occluded patch test. 1/2 of the 20 patients only reacted to 10,000 ppm formaldehyde. 9 reacted to 5,000 ppm. 3 reacted to 1.000 ppm. 2 reacted to 500 ppm and I reacted to 25 ppm. No definite positive reactions were observed in the non-occluded patch test or in the ROAT No positive reactions were observed in the control group to any of the test procedures. We concluded that the threshold concentration for occluded patch test to formaldehyde in formaldehyde-sensitive patients was 250 ppm. The threshold in occluded patch test corresponded to the degree of sensitivity Definite positive reactions in the ROAT were not seen, either indicating that they are unlikely to happen with the type of product used or that the exposure time was too short. 相似文献
103.
104.
Capsaicin cough sensitivity in allergic asthmatic patients increases during the birch pollen season. 总被引:1,自引:0,他引:1
Dan Weinfeld Ewa Ternesten-Hasséus Olle L?whagen Eva Millqvist 《Annals of allergy, asthma & immunology》2002,89(4):419-424
BACKGROUND: A change in neural responsiveness may occur as the result of allergic inflammation in the lower airways as well as in the upper airways. In the lower airways, capsaicin cough sensitivity is known to reflect sensory neural reactivity. OBJECTIVE: The aim of this study was to establish whether allergic inflammation changes airway neural sensory reactivity during prolonged allergen exposure. METHODS: Ten nonsmoking patients with birch pollen-allergic asthma performed a capsaicin inhalation challenge twice, once in the off-pollen season and once during the pollen season. The number of coughs and symptoms induced by capsaicin were recorded and compared with those of healthy control subjects. RESULTS: The response to capsaicin, expressed as number of coughs, increased in a dose-dependent manner during both tests. Before the season, the response was similar to that of healthy control subjects, but during the pollen season, the reactivity was significantly increased. Variations in forced expiratory volume in 1 second were not significant before and after each challenge, and values did not change during the pollen season as compared with the winter season. CONCLUSIONS: Sensory reactivity in allergic asthmatic patients may be increased during prolonged allergen exposure as during the pollen season. This finding suggests that allergic inflammation in the lower and/or upper airways may trigger neurogenic mechanisms of significant clinical importance. 相似文献
105.
István Pintér János Mátyus Zoltán Czégány Judit Harsányi Marietta Homoki Miklós Kassai Eva Kiss István Kiss Erzsébet Ladányi Lajos Locsey Lajos Major Mihály Misz Lajos Nagy Kálmán Polner Jeno Rédl István Solt Béla Tichy Marietta T?r?k Gábor Varga Gyula Wagner Imre Wórum Béla Zsoldos László Pótó Katalin Dérczy István Wittmann Judit Nagy 《Nephrology, dialysis, transplantation》2004,19(4):840-843
BACKGROUND: The diagnosis of analgesic nephropathy has improved significantly with modern imaging techniques. We reviewed a large portion of the Hungarian dialysis population to obtain additional insight into the problem. METHODS: Twenty-two participating dialysis units enrolled 1400 patients on renal replacement therapy between 1 January 1995 and 1 January 1998. Patients with no known aetiology (n = 284) were interviewed and studied with renal imaging. We assessed the presence of decreased renal mass combined with either bumpy contours, papillary calcification, or both. The subjects studied were interrogated extensively. RESULTS: Our survey suggested analgesic nephropathy in 47 of 1400 patients (3.3%), 3-fold higher than the EDTA database estimate for Hungary. The analgesics most commonly abused were phenacetin-containing mixtures. The driving symptoms were mainly headache and joint pain. Cardiovascular complications were more common than in the rest of the dialysis population, independent of smoking and lipid values (P<0.01). CONCLUSIONS: Phenacetin should be banned. Our study results support the need for longitudinal cohort and case-control studies in Hungary. 相似文献
106.
C Castelo-Branco M J Martínez de Osaba F Pons J González-Merlo 《European journal of obstetrics, gynecology, and reproductive biology》1992,44(2):131-136
Eighty-four postmenopausal women who were randomly allocated to one of four groups, completed a 1 year follow-up. The first group (n = 20) received 0.625 mg/day conjugated estrogens cyclically (CE; 25 days/month). The second (n = 23) received 0.625 mg/day of CE continuously, and the third (n = 17) received 50 micrograms/day of transdermal 17 beta-estradiol cyclically (24 days/month). All these groups also received 2.5 mg of medroxiprogesterone acetate sequentially for the last 12 days of hormone replacement therapy, while the fourth group (n = 24) constituted a treatment-free control group. Dual photon absorptiometry was carried out before therapy and was repeated after 1 year. Serum calcium, phosphate and osteocalcine levels, and the urinary calcium/creatinine and hydroxyproline/creatinine ratios, were measured prior to treatment and 6 and 12 months thereafter. All treatment groups showed an increase in bone mineral content. This increase was higher in the continuous CE treatment group (4.4%, P less than 0.05) and in transdermal group (7.1%, P less than 0.01). Concomitant biochemical effects at 6 and 12 months, reduction in urine calcium and hydroxyproline, reduction in blood calcium, phosphate and osteocalcine, were compatible with the observed effects on bone mineral. 相似文献
107.
J L Pérez Arellano N M Barrios González T Martín Domínguez M L Sánchez Benítez de Soto A Jiménez López 《Journal of investigational allergology & clinical immunology》1992,2(4):219-228
Experimental models of hypersensitivity pneumonitis are important tools for the study of the pathogenesis of this disease. In this paper we review the characteristics of the main animal models developed until now. The HP models in rats seem to be particularly appropriate for studying pigeon fancier's disease and the HP induced by chemicals, as well as for studying mediators of acute lesions induced by immunocomplexes. However, the HP models developed in rats are of less value in the evaluation of other aspects of the pathogenesis of this clinical entity in humans. The murine models of HP offer several advantages: the ease and simplicity of intranasal administration, the ability to produce acute and subacute pulmonary lesions similar to those found in humans, the possibility of reproducing lesions similar to those of nonaffected exposed subjects and the possibility of pharmacologically modulating the process. Their disadvantages lie in the different pulmonary lymphocyte response and the difficulty in reproducing a model of chronic fibrosis. The HP models in rabbits are extraordinarily useful for evaluating the immunological mechanisms through which subjects repeatedly exposed to the antigen do not develop clinical manifestations. However, the rabbit has several immunological differences when compared to humans, and the effect of some immunomodulators in this animal is different. The models of HP in guinea-pigs have as advantages the ease in handling the animals, the possibility of pharmacological manipulation, and the ability to induce an acute phase that is very similar to that observed in humans. The drawback, however, is the low lymphocyte response and the striking eosinophilic reaction that contrast with the bronchoalveolar data found in HP in humans. In conclusion, there is no ideal model to reproduce all the findings observed in humans, suggesting that the experimental animal and the method of developing HP should be selected on the basis of concrete research aims. 相似文献
108.
109.
M Girbau P R González-Guerrero L Bassas F de Pablo 《Molecular and cellular endocrinology》1992,90(1):69-75
The demonstration of growth factor receptors in very young embryos is limited by the difficulty in obtaining sufficient tissue to yield adequate membrane preparations. We have developed an in situ binding technique that allowed quantitation of [125I]insulin and [125I]insulin-like growth factor-I (IGF-I) binding to individual chick embryos. Specific binding per embryo increased from the youngest stage studied (Hamburger and Hamilton (HH) stages 3-4, gastrulating embryo of approximately 18-20 h) until the third day of development. At all ages, the binding of [125I]IGF-I was several fold higher than the binding of [125I]insulin. Autophosphorylation of the beta-subunit of the receptors was stimulated by insulin and IGF-I in a stage- and dose-dependent manner. The two peptides did not have an additive effect. The present studies further support our previous data showing the early developmental appearance of insulin and IGF-I receptors, which very likely are essential for normal embryo development. In addition, this in situ method for demonstration of receptors can be applied to other types of receptors present in isolated organs and young embryos. 相似文献
110.
Bego?a López Arantxa González Ramón Querejeta Mariano Larman Javier Díez 《Journal of the American College of Cardiology》2006,48(1):89-96
OBJECTIVES: We sought to assess the distribution of collagen deposits and collagen degradation in hypertensive patients with either systolic heart failure (SHF) or diastolic heart failure (DHF). BACKGROUND: Increased collagen synthesis and deposition have been described in the myocardium of heart failure (HF) hypertensive patients. METHODS: We studied 39 HF hypertensive patients subdivided into two groups: 16 with SHF and 23 with DHF. Endomyocardial biopsies were performed to quantify mysial (i.e., perimysial plus endomysial) and perivascular and scar-related collagen volume fraction (CVF). Matrix metalloproteinase (MMP)-1 and its tissue inhibitor matrix metalloproteinase (TIMP)-1 were analyzed in cardiac samples by Western blot and immunohistochemistry, and in blood samples by enzyme-linked immunosorbent assay. RESULTS: Mysial CVF was lower in SHF hypertensive patients than in normotensive (p < 0.05) and DHF hypertensive patients (p < 0.01). Perivascular and scar-related CVF was higher (p < 0.05) in the two groups of hypertensive patients than in normotensive subjects, and in SHF hypertensive compared with DHF hypertensive patients. The MMP-1:TIMP-1 ratio was increased (p < 0.05) in tissue and serum samples from the SHF hypertensive group compared with the other two groups of subjects. The MMP-1 expression was increased (p < 0.01) in the interstitium and cardiomyocytes of SHF hypertensive patients compared with DHF hypertensive and normotensive subjects. The serum MMP-1:TIMP-1 ratio was inversely correlated with ejection fraction (r = -0.510, p < 0.001) and directly correlated with left ventricular end-diastolic diameter (r = 0.549, p < 0.001) in all subjects. CONCLUSIONS: These findings show that the pattern of collagen deposits and the balance of the MMP-1/TIMP-1 system are different in the myocardium of SHF and DHF hypertensive patients. It is proposed that excessive degradation of mysial collagen may be related to the compromise of systolic function in HF hypertensive patients. 相似文献