全文获取类型
收费全文 | 13041篇 |
免费 | 626篇 |
国内免费 | 125篇 |
专业分类
耳鼻咽喉 | 70篇 |
儿科学 | 299篇 |
妇产科学 | 435篇 |
基础医学 | 1445篇 |
口腔科学 | 172篇 |
临床医学 | 1033篇 |
内科学 | 3123篇 |
皮肤病学 | 321篇 |
神经病学 | 1289篇 |
特种医学 | 535篇 |
外科学 | 2315篇 |
综合类 | 31篇 |
一般理论 | 1篇 |
预防医学 | 491篇 |
眼科学 | 252篇 |
药学 | 806篇 |
中国医学 | 30篇 |
肿瘤学 | 1144篇 |
出版年
2024年 | 18篇 |
2023年 | 100篇 |
2022年 | 274篇 |
2021年 | 358篇 |
2020年 | 221篇 |
2019年 | 267篇 |
2018年 | 335篇 |
2017年 | 248篇 |
2016年 | 330篇 |
2015年 | 390篇 |
2014年 | 479篇 |
2013年 | 660篇 |
2012年 | 1024篇 |
2011年 | 1009篇 |
2010年 | 644篇 |
2009年 | 536篇 |
2008年 | 859篇 |
2007年 | 852篇 |
2006年 | 769篇 |
2005年 | 777篇 |
2004年 | 711篇 |
2003年 | 594篇 |
2002年 | 559篇 |
2001年 | 154篇 |
2000年 | 141篇 |
1999年 | 146篇 |
1998年 | 127篇 |
1997年 | 78篇 |
1996年 | 90篇 |
1995年 | 83篇 |
1994年 | 79篇 |
1993年 | 61篇 |
1992年 | 101篇 |
1991年 | 88篇 |
1990年 | 75篇 |
1989年 | 70篇 |
1988年 | 52篇 |
1987年 | 57篇 |
1986年 | 54篇 |
1985年 | 35篇 |
1984年 | 37篇 |
1983年 | 32篇 |
1982年 | 21篇 |
1981年 | 16篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 12篇 |
1975年 | 15篇 |
1969年 | 13篇 |
1968年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
Vincenzo Neri Antonio Ambrosi Giuseppe Di Lauro Tiziano Pio Valentino 《JSLS, Journal of the Society of Laparoendoscopic Surgeons》2006,10(1):66-69
OBJECTIVES: The aim of this study was to evaluate the safety and effectiveness of laparoscopic-assisted sigmoid colectomy for diverticulitis and to assess its postoperative advantages. METHODS: From 1999 to 2001, 5 patients were selectively operated on with a laparoscopic-assisted procedure for uncomplicated sigmoid diverticulitis. In the preceding period (September 1997 through December 1998), 4 patients underwent open procedures for the same pathology. The surgical indication with the same criteria was restrictive: at least 2 acute episodes had occurred that were treated with hospital admission and that were separated by an adequate period (2 months) of medical therapy. RESULTS: No conversions of laparoscopy to an open procedure were necessary. Age, sex, weight, morbidity, and mortality were similar between the 2 groups. Operative time was 180 minutes for laparoscopy and 120 minutes for laparotomy. Postoperative resumption of peristalsis was 24 hours versus 4 days, resumption of alimentation was on the second postoperative day versus the fifth postoperative day, and hospital stay was 7 days versus 12 days for laparoscopy and laparotomy, respectively. CONCLUSION: This study shows the feasibility and the advantages of elective laparoscopic-assisted colonic resection for uncomplicated sigmoid diverticulitis. The advantages of the laparoscopic approach are the lower need for analgesics and the more precocious ambulation, canalization, resumption of alimentation, and the shorter hospital stay. 相似文献
12.
13.
Carmine Zoccali Renke Maas Sebastiano Cutrupi Patrizia Pizzini Piero Finocchiaro Francesco Cambareri Vincenzo Panuccio Carmela Martorano Friedrich Schulze Giuseppe Enia Giovanni Tripepi Rainer Boger 《Nephrology, dialysis, transplantation》2007,22(3):801-806
BACKGROUND AND METHODS: The endogenous inhibitor of nitric oxide synthase (NOs) asymmetrical dimethyl-arginine (ADMA) has been implicated as a possible modulator of inducible NOs during acute inflammation. We examined the evolution in the plasma concentration of ADMA measured at the clinical outset of acute inflammation and after its resolution in a series of 17 patients with acute bacterial infections. RESULTS: During the acute phase of inflammation/infection, patients displayed very high levels of C-reactive protein (CRP), interleukin-6 (IL-6), procalcitonin and nitrotyrosine. Simultaneous plasma ADMA concentration was similar to that in healthy subjects while symmetric dimethyl-arginine (SDMA) levels were substantially increased and directly related with creatinine. When infection resolved, ADMA rose from 0.62 +/- 0.23 to 0.80 +/- 0.18 micromol/l (+29%, P = 0.01) while SDMA remained unmodified. ADMA changes were independent on concomitant risk factor changes and inversely related with baseline systolic and diastolic pressure. Changes in the ADMA/SDMA ratio were compatible with the hypothesis that inflammatory cytokines activate ADMA degradation. CONCLUSIONS: Resolution of acute inflammation is characterized by an increase in the plasma concentration of ADMA. The results imply that ADMA suppression may actually serve to stimulate NO synthesis or that in this situation plasma ADMA levels may not reflect the inhibitory potential of this methylarginine at the cellular level. 相似文献
14.
Synergistic antiproliferative activity of quercetin and cisplatin on ovarian cancer cell growth 总被引:1,自引:0,他引:1
G Scambia F O Ranelletti P Benedetti Panici G Bonanno R De Vincenzo M Piantelli S Mancuso 《Anti-cancer drugs》1990,1(1):45-48
It has been demonstrated that the flavonoid quercetin (3,3',4',5-7-pentahydroxyflavone) (Q) inhibits the growth of several cancer cell lines and that the antiproliferative activity of this substance is mediated by a so-called type II estrogen binding site (type II EBS). We investigated the effects of quercetin and cisplatin (CDDP) alone and in combination on the proliferation of the ovarian cancer cell line OVCA 433. Both drugs exhibited a dose-related growth inhibition in a range of concentrations between 0.01 and 2.5 microM and 0.01 and 2.5 micrograms/ml for Q and CDDP respectively. The combination of the two drugs resulted in a synergistic antiproliferative activity. Two other flavonoids tested, i.e., rutin (3-rhamnosylglucoside of quercetin) and hesperidin [7-b rutinoside of hesperetin (3'-5-3-hydroxy-4-methoxyflavone)] were ineffective both alone and in combination with CDDP. Since both rutin and hesperidin do not bind to type II EBS it can be hypothesized that Q synergizes with CDDP by acting through an interaction with these binding sites. 相似文献
15.
Daily nutrient intake represents a modifiable determinant of nutritional status in chronic haemodialysis patients. 总被引:2,自引:0,他引:2
Vincenzo Bellizzi Biagio R Di Iorio Vincenzo Terracciano Roberto Minutolo Carmela Iodice Luca De Nicola Giuseppe Conte 《Nephrology, dialysis, transplantation》2003,18(9):1874-1881
BACKGROUND: In maintenance haemodialysis patients, daily food intake is changeable; however, its relationship with nutritional status is unexplored. This study aimed to evaluate the isolated, long-term effect of daily nutrient intake on nutritional status in haemodialysis patients. METHODS: We performed a prospective 1-year controlled study in 27 chronic haemodialysis patients, without recognized risk factors for malnutrition. Each day for 1 week, four times in the year, we measured protein nitrogen appearance, and assessed dietary protein (DPI) and energy (DEI) intake from dietary diaries. We compared the nutritional outcome of patients spontaneously reducing nutrient intake below the threshold of 0.8 g/kg body weight/day for DPI and 25 kcal/kg body weight/day for DEI during the week (LOW, n = 8), with controls at adequate nutrient intake (CON, n = 19). An interventional 6-month study was then carried out in LOW to verify the cause-effect relationship. RESULTS: All patients showed a day-by-day reduction of whole nutrient intake during interdialytic period, which was mostly relevant in the third interdialytic day (L3). During the 1-year study, even in the presence of adequate dialysis dose and normal inflammatory indexes, body weight (68.0 +/- 5.5 to 65.8 +/- 5.9 kg), serum albumin (3.96 +/- 0.07 to 3.66 +/- 0.06 g/dl) and creatinine (9.2 +/- 1.1 to 8.1 +/- 0.7 mg/dl) significantly decreased in LOW but not in CON. Diaries evidenced in LOW a reduced number of meals at L3 that was explained by the fear of excessive interdialytic weight gain. During the interventional study, daily DPI and DEI increased at L3; this was associated with a significant increment of body weight, and serum albumin and creatinine levels. CONCLUSIONS: In maintenance haemodialysis patients the persistent, marked reduction of daily nutrient intake, even if limited to a single day of the week, is an independent determinant of reversible impairment of nutritional status. 相似文献
16.
Posterior ischemic optic neuropathy during general surgery 总被引:3,自引:0,他引:3
We examined two patients who awoke with profound bilateral visual loss after operations under general anesthesia. Their fundi, initially normal, later showed bilateral optic atrophy. Neither patient showed other neurologic deficits, although one demonstrated radiologic evidence of a small cerebral infarction in the deep white matter. These patients probably suffered intraoperative infarction of the retrobulbar segments of both optic nerves, producing posterior ischemic optic neuropathy. Profound systemic hypotension may have been a contributing factor in one patient, the use of the pump-oxygenator in the other, and anemia in both. 相似文献
17.
Gazzaniga P. P. Ferroni P. Mina C. Pulcinelli F. M. Rizzo P. A. 《The Italian Journal of Neurological Sciences》1987,8(6):561-566
148 patients with various forms of cerebrovascular disease (CVD) were studied by means of a multiparametric analysis ofin vitro platelet aggregation, based on the following six parameters: ADP and epinephrine primary and secondary aggregation thresholds
and percent maximum aggregation induced by optimal concentrations of ADP and epinephrine. These patients were assigned to
four study groups, according to clinical diagnosis supported by CT scan, of transient ischemic attack and reversible neurological
deficit (TIA-RIND), or completed stroke, in the presence or absence respectively of antiplatelet medical treatment at the
time of the study. A statistically significant increase of thein vitro platelet aggregation was found in 44.4% of the untreated TIA-RIND patients and in 33.9% of the untreated stroke patients.
However this last group showed a higher percentage of very marked hyperaggregation. Differences between the two treated study
groups and controls were not signicant. No difference was found in collagen-and ristocetin-induced aggregation between the
patient groups and the controls.
Sommario 148 pazienti con varie forme di malattia cerebrovascolare, sono stati studiati con analisi multiparametriche dell'aggregazione piastrinica in vitro sulla base dei seguenti sei parametri: le soglie di aggregazione primaria e secondaria e l'aggregazione massima percentuale indotta da ADP ed Epinefrina. Questi pazienti sono stati suddivisi in 4 gruppi di studio in accordo con la diagnosi clinica confortata dai dati della TAC e cioè: TIA, RIND, o rammollimento in presenza o in assenza rispettivamente di un trattamento antiaggregante nel momento dello studio. è stato trovato un aumento statisticamente significativo dell'aggregazione in vitro delle piastrine nel 44.4% dei casi TIA, RIND non trattati e nel 33,9% dei casi di rammollimento non trattati. Quest'ultimo gruppo, però, ha dimostrato una più alta percentuale di iperaggregazione molto marcata. Le differenze tra i 2 gruppi di studio trattati con antiaggreganti e i controlli non erano significative. Inoltre nessuna differenza è stata riscontrata tra i gruppi e i controlli nell'aggregazione indotta da collageno e ristocetina.相似文献
18.
19.
Silvia Miano Oliviero Bruni Vincenzo Leuzzi Maurizio Elia Elisabetta Verrillo Raffaele Ferri 《Clinical neurophysiology》2004,115(4):938-945
OBJECTIVE: Sleep disturbances are frequent in Angelman syndrome (AS); however, beside the few studies which have investigated sleep disorders in AS by means of questionnaires, to our knowledge, no systematic polysomnographic recordings have been carried out in AS patients. The present study represents the first attempt to study sleep patterns of AS by polysomnography, to evaluate the influences of sleep on the paroxysmal electroencephalogram (EEG) patterns of AS and to assess the eventual age-related changes of sleep architecture and of sleep EEG abnormalities in children and adolescents with AS. METHODS: Fifteen children with AS (7 males and 8 females, mean age 7.2 years, range 3-16 years), attending the Sleep Center of the Department of Child Neurology and Psychiatry of the University of Rome 'La Sapienza' and the Sleep Research Centre of the Oasi Institute (IRCCS) of Troina were included and subdivided into two subgroups by age: subgroup 1, aged 3-5 years, and subgroup 2, aged 9-17 years. Two control groups of age-matched normal subjects were also included: one aged less than 8 years and another aged more than 8 years; additionally, two other groups of age-matched children with epilepsy and mental retardation of different origin, one aged less and one aged more than 9 years were taken into consideration. The statistical comparison between the sleep parameters obtained from the patients and those from the other groups was carried out by means of the non-parametric Kruskal-Wallis ANOVA and the Mann-Whitney U test. RESULTS: The most frequent EEG abnormality found in AS patients appeared to be the 2-3 c/s poorly defined spike/waves complexes. This pattern was influenced by sleep stages; the duration of the runs showed an increasing length with sleep deepening from sleep stage 1 to slow-wave sleep (SWS). Moreover, the 2-3 c/s bursts activity present in sleep stage 2 showed a slowing to 1-2 c/s during SWS. Regarding sleep architecture, in subjects with AS aged <8 year there was a significant reduction in sleep efficiency as compared to normal controls, while the percentage and duration of REM sleep was significantly lower and the percentage of SWS was significantly higher. REM sleep time was reduced in AS subjects aged >8 years than in normal controls. The comparison between AS groups and mental retardation with epilepsy groups did not show significant differences. CONCLUSIONS: Similarly to other types of genetically determined mental retardation syndromes, also subjects with AS seems to show important abnormalities of their sleep polysomnographic patterns. SIGNIFICANCE: This is the first study which reports, in detail, these abnormalities and opens a new path for further insight into the knowledge of additional sleep-related disturbances which are reported in sleep questionnaires by the caregivers of AS subjects. 相似文献
20.
Paolo Martinelli Giovanni Rizzo David Manners Caterina Tonon Fabio Pizza Claudia Testa Cesa Scaglione Bruno Barbiroli Raffaele Lodi 《Movement disorders》2007,22(8):1182-1185
The pathophysiology of essential tremor (ET) is unknown. PET and fMRI studies have revealed bilateral activation and (1)H-MRS studies metabolic abnormalities in the cerebellum and other functionally related brain structures in ET. Diffusion-weighted imaging (DWI) was used to search for evidence of tissue integrity abnormalities in these areas in ET patients and 10 matched controls by calculating water apparent diffusion coefficients (ADCs). Regions of interest included the left and right cerebellum, red nucleus, thalamus, caudate, putamen, pallidum, and frontal white matter. Histograms of ADCs were generated for all pixels in the infratentorial compartment and manually segmented areas corresponding to brainstem, vermis, and cerebellar hemispheres. ADC values were similar in all brain areas in patients and controls. Our study did not detect changes affecting the investigated brain regions in ET patients. These findings argue against major structural damage in the ET brain, although more subtle neurodegenerative changes cannot be ruled out. 相似文献