全文获取类型
收费全文 | 5149篇 |
免费 | 311篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 22篇 |
儿科学 | 216篇 |
妇产科学 | 122篇 |
基础医学 | 564篇 |
口腔科学 | 146篇 |
临床医学 | 371篇 |
内科学 | 1692篇 |
皮肤病学 | 78篇 |
神经病学 | 391篇 |
特种医学 | 232篇 |
外国民族医学 | 1篇 |
外科学 | 558篇 |
综合类 | 66篇 |
一般理论 | 1篇 |
预防医学 | 211篇 |
眼科学 | 29篇 |
药学 | 358篇 |
中国医学 | 11篇 |
肿瘤学 | 412篇 |
出版年
2023年 | 28篇 |
2022年 | 41篇 |
2021年 | 112篇 |
2020年 | 49篇 |
2019年 | 98篇 |
2018年 | 128篇 |
2017年 | 97篇 |
2016年 | 107篇 |
2015年 | 87篇 |
2014年 | 151篇 |
2013年 | 219篇 |
2012年 | 257篇 |
2011年 | 256篇 |
2010年 | 172篇 |
2009年 | 169篇 |
2008年 | 218篇 |
2007年 | 258篇 |
2006年 | 241篇 |
2005年 | 235篇 |
2004年 | 201篇 |
2003年 | 189篇 |
2002年 | 188篇 |
2001年 | 166篇 |
2000年 | 171篇 |
1999年 | 158篇 |
1998年 | 78篇 |
1997年 | 77篇 |
1996年 | 74篇 |
1995年 | 77篇 |
1994年 | 58篇 |
1993年 | 48篇 |
1992年 | 103篇 |
1991年 | 64篇 |
1990年 | 83篇 |
1989年 | 76篇 |
1988年 | 70篇 |
1987年 | 74篇 |
1986年 | 63篇 |
1985年 | 62篇 |
1984年 | 55篇 |
1983年 | 66篇 |
1982年 | 32篇 |
1981年 | 26篇 |
1980年 | 26篇 |
1979年 | 29篇 |
1978年 | 27篇 |
1976年 | 24篇 |
1975年 | 30篇 |
1974年 | 26篇 |
1970年 | 20篇 |
排序方式: 共有5481条查询结果,搜索用时 15 毫秒
41.
Ohne Zusammenfassung 相似文献
42.
Lexical priming deficits as a function of age 总被引:2,自引:0,他引:2
H P Davis A Cohen M Gandy P Colombo G VanDusseldorp N Simolke J Romano 《Behavioral neuroscience》1990,104(2):288-297
The effects of age on implicit memory were assessed in elderly young adults using 2 priming procedures. Subjects also completed the WAIS-R, 3 tests to assess frontal lobe function, and 2 recall and 2 recognition tests of explicit memory. In Experiment 1, subjects were exposed to the low-frequency member of a homophone pair in a test purported to assess general knowledge. Subsequently, subjects completed a spelling test that contained the previously presented homophones to assess priming. Young subjects demonstrated priming (p less than .01). Elderly subjects demonstrated a high baseline that may have obscured priming. In Experiment 2, subjects from each decade of life from the 20s through the 80s were given a word-stem completion test of priming. All age conditions demonstrated an effect of priming (p less than .01). However, subjects in their 70s and 80s demonstrated lower priming scores (p less than .05). Elderly subjects were also impaired on immediate-and delayed-recall tests. These results suggest an age-related decline in both implicit and explicit memory. 相似文献
43.
Paolo Colombo Pierino Radici Sergio Custro Mario Ermoni 《Macromolecular chemistry and physics.》1977,178(1):1-10
Attempts were made to elucidate experimentally the behaviour of poly(oxymethylene)-diol [α-hydro-ω-hydroxypoly(oxymethylene)] in the etherification reaction in order to explain the decrease of the polymer molecular weight compared with that of the starting product and in order to determine the type of terminal groups and how the thermal resistance and alkali stability can be affected. In fact one finds that, in addition to the wanted terminal ether groups, formyl and orthoformyl (dialkoxymethyl) groups are formed having a different chemical resistance in comparison to that of the pure ethers, particularly in basic media. 相似文献
44.
M G Rumi R Romeo M Bortolini A Gringeri A R Zanetti P M Mannucci M Colombo 《Journal of medical virology》1989,27(1):48-51
Horizontal transmission of hepatitis B virus (HBV) from illicit drug users to their contacts, including young children, can be prevented by active immunization against HBV. Yeast-recombinant hepatitis B vaccines are now available for this purpose, but their potential efficacy in such high-risk contacts has not yet been evaluated. Therefore we gave 20 mcg of a recombinant yeast-derived hepatitis B vaccine to 38 children who were at high risk for HBV infection because they had been institutionalized in a community for drug users in which 8.7% of the occupants are carriers. After third dose of vaccine (at 0, 1, and 6 months), all children had anti-HBs responses with titers of 10 mIU/ml or more, with 81% showing responses greater than 1,000 mIU/ml. At 12 months, the percentage of anti-HBs-positive children was 100%, and the percentage of children with anti-HBs higher than 1,000 mIU/ml was 56%. None of the children developed HBV infection during follow-up. Hence the recombinant vaccine was immunogenic, with percentages of seroconversion and anti-HBs titers comparable with those attained in other categories of high-risk children with plasma-derived vaccines. 相似文献
45.
G Morone A Tazzi G Carella A Ghisolfi R Colombo 《Journal fran?ais d'ophtalmologie》1985,8(8-9):555-558
The authors describe the pathological changes in the vascular structures of the ciliary body occuring in diabetes mellitus. The lesions consist of a quantitative reduction in the number of vessels and in modifications of diameter and arborisation. Changes include sectoral thinning, isolated and grouped aneuryms and marked tortuosity. These findings are thought to be constant in the diabetic patient and are probably involved in the various aspects of diabetic eye disease affecting other structures besides the ciliary body. The group of vascular changes in the ciliary body in diabetes may aptly be termed "diabetic ciliopathy". 相似文献
46.
The possibility of a preferential distribution of projections from the preoptic-suprachiasmatic region (POA-Sch) to the median eminence in the male rat was studied using autoradiographic and computer procedures. A cocktail of [3H]leucine-[3H]proline was injected into the POA-Sch. Animals were killed after either 1, 4, or 24 h of incorporation time (IT). The number of silver grains per 25-micron square was counted throughout the median eminence. Squares with silver grain densities at or above the 75 percentile of the population for any given IT group were labeled as "concentrating areas." The distribution of these concentrating areas in median eminence tissue was analyzed utilizing univariate procedures. Visual inspection of the distribution of silver grain densities in a rostrocaudal fashion indicated the likelihood of uneven distribution; however, these differences were not statistically significant. In the dorsoventral plane, results indicated that the highest silver grain density was at 50 to 75 micron from the floor of the 3rd ventricle. Such distribution was apparent both ipsi- and contralateral to the injection site, but was greater on the ipsilateral side. 相似文献
47.
Galassi G. Modena M. G. Benassi A. Nemni R. Gibertoni M. Volpi G. Colombo A. 《The Italian Journal of Neurological Sciences》1986,7(1):125-132
Two females mother and daughter, were affected by a neuromuscular disorder, characterized by slow progression, humeroperoneal weakness and wasting, limited neck flexion, elbow and ankle joint contractures, cardiopathy and myopathic pattern on EMG. Muscle histology and histochemistry showed type I fiber atrophy and predominance in both. Cardiac abnormalities, in the first case, were suggestive of a hypertrophic cardiomyopathy while in the second hypotension and chronic bradycardia were present.Neurological signs, EMG and morphology seemed to point to a genetic variant of the form of dystrophy named Emergy-Dreifuss disease.The mode of transmission and cardiac abnormalities, however, raise the problem of variability even in this well-defined, usually X-linked, disorder.
Sommario Questa è la prima descrizione di madre e figlia affette da una infrequente malattia muscolare, caratterizzata da progressione lenta, ipostenia con atrofia a distribuzione omero-peroneale, presenza di contratture articolari, cardiopatia e pattern miopatico dell'EMG.Istologia e istochimica muscolare hanno mostrato in entrambi i soggetti atrofia e predominanza delle fibre del I tipo. Le anormalità cardiologiche rilevate nel 1° caso, erano a favore di una cardiomiopatia ipertrofica, mentre nel secondo caso erano presenti ipotensione e bradicardia.Segni neurologici, elettromiografici, reperti istologici ed istochimici sembrano configurare nelle nostre pazienti una variante genetica della forma di distrofia muscolare chiamata Emery-Dreifuss disease. Tuttavia, la modalità di trasmissione e il tipo delle anormalità cardiologiche, diverse nelle due pazienti, sollevano il problema di variabilità fenotipiche, anche in entità clinico-genetiche usualmente ben definite quali la malattia di Emery-Dreifuss.相似文献
48.
R C Avanzo G Chierego C Marchetti F Pozza F Colombo A Benedetti A Zanardo 《La Radiologia medica》1984,70(3):124-129
At least two fundamental requirements must subsist for every stereotaxic radiotherapy treatment: 1) a capacity to administer extremely high doses of radiation to small areas which have been precisely defined in three dimensions; 2) the presence of a steep gradient between adjacent isodose curves so that damage to the tissues close to the target may be reduced to the minimum. The authors have built a special stereotaxic device for the fixing of the head of the patient (together with the chosen intracranial target), once the indispensable neuroradiological evaluations and bioptic controls have been effected, at the isocenter of a linear accelerator (Varian Clinac 4). Once the dimensions of the collimator have been chosen in accordance with the volume and the three dimensional conformation of the target and the dose to be administered has been decided upon in accordance with the histological nature of the lesion, both the linear accelerator and the patient are rotated about the isocenter of the therapy unit. It this way it is possible to reach extremely high dosages with very steep isodose gradients, centered exclusively upon the target ("gamma knife"). The procedure employed is described in full. The dosimetric evaluations which preceded the use of the set-up in clinical practice are illustrated as well. The advantages that this technique offers when compared with interstitial brachytherapy and/or Leksell's radiosurgical procedures are stressed. The described procedure, which is entirely bloodless and thus applicable also to high vascularized lesions, has so far been used in a limited series of cases. 相似文献
49.
Chiara Di Lorenzo Francesca Colombo Simone Biella Creina Stockley Patrizia Restani 《Nutrients》2021,13(1)
Polyphenols are a group of phytochemicals with potential health-promoting effects. They are classified as flavonoid (flavonols, flavanols, flavones, flavanones, isoflavones, and anthocyanins) and non-flavonoid molecules (phenolic acids, hydroxycinnamic acids, lignans, stilbenes, and tannins). Although an increasing number of trials have shown a correlation among polyphenol consumption and a reduction in risk factors for chronic diseases, discrepancies in explaining their positive effects have been found in terms of the bioavailability. In fact, polyphenols show a low bioavailability due to several factors: interaction with the food matrix, the metabolic processes mediated by the liver (phase I and II metabolism), intestine and microbiota. On the other hand, the biological activities of phenol compounds may be mediated by their metabolites, which are produced in vivo, and recent studies have confirmed that these molecules may have antioxidant and anti-phlogistic properties. This review discusses the studies performed in vivo, which consider the polyphenol bioavailability and their different food sources. Factors influencing the biological effects of the main classes of polyphenols are also considered. 相似文献
50.
F. Pisano P. Gontero R. Sylvester S. Joniau V. Serretta S. Larré S. Di Stasi B. van Rhijn A. Witjes A. Grotenhuis R. Colombo A. Briganti M. Babjuk V. Soukup P.U. Malmstrom J. Irani N. Malats J. Baniel J. Palou 《Actas urologicas espa?olas》2021,45(6):473-478
Introduction and objectivesThe goals of transurethral resection of a bladder tumor (TUR) are to completely resect the lesions and to make a correct diagnosis in order to adequately stage the patient. It is well known that the presence of detrusor muscle in the specimen is a prerequisite to minimize the risk of under staging.Persistent disease after resection of bladder tumors is not uncommon and is the reason why the European Guidelines recommended a re-TUR for all T1 tumors. It was recently published that when there is muscle in the specimen, re-TUR does not influence progression or cancer specific survival.We present here the patient and tumor factors that may influence the presence of residual disease at re-TUR.Material and methodsIn our retrospective cohort of 2451 primary T1G3 patients initially treated with BCG, pathology results for 934 patients (38.1%) who underwent re-TUR are available. 74% had multifocal tumors, 20% of tumors were more than 3 cm in diameter and 26% had concomitant CIS.In this subgroup of patients who underwent re-TUR, there was no residual disease in 267 patients (29%) and residual disease in 667 patients (71%): Ta in 378 (40%) and T1 in 289 (31%) patients. Age, gender, tumor status (primary/recurrent), previous intravesical therapy, tumor size, tumor multi-focality, presence of concomitant CIS, and muscle in the specimen were analyzed in order to evaluate risk factors of residual disease at re-TUR, both in univariate analyses and multivariate logistic regressions.ResultsThe following were not risk factors for residual disease: age, gender, tumor status and previous intravesical chemotherapy. The following were univariate risk factors for presence of residual disease: no muscle in TUR, multiple tumors, tumors > 3 cm, and presence of concomitant CIS. Due to the correlation between tumor multi-focality and tumor size, the multivariate model retained either the number of tumors or the tumor diameter (but not both), p < 0.001. The presence of muscle in the specimen was no longer significant, while the presence of CIS only remained significant in the model with tumor size, p < 0.001.ConclusionsThe most significant factors for a higher risk of residual disease at re-TUR in T1G3 patients are multifocal tumors and tumors more than 3 cm. Patients with concomitant CIS and those without muscle in the specimen also have a higher risk of residual disease. 相似文献