全文获取类型
收费全文 | 44970篇 |
免费 | 2753篇 |
国内免费 | 256篇 |
专业分类
耳鼻咽喉 | 388篇 |
儿科学 | 1294篇 |
妇产科学 | 1201篇 |
基础医学 | 5927篇 |
口腔科学 | 938篇 |
临床医学 | 4493篇 |
内科学 | 9830篇 |
皮肤病学 | 880篇 |
神经病学 | 4791篇 |
特种医学 | 1498篇 |
外科学 | 5908篇 |
综合类 | 175篇 |
一般理论 | 19篇 |
预防医学 | 3350篇 |
眼科学 | 767篇 |
药学 | 2773篇 |
1篇 | |
中国医学 | 85篇 |
肿瘤学 | 3661篇 |
出版年
2024年 | 70篇 |
2023年 | 520篇 |
2022年 | 998篇 |
2021年 | 1801篇 |
2020年 | 1056篇 |
2019年 | 1484篇 |
2018年 | 1699篇 |
2017年 | 1191篇 |
2016年 | 1336篇 |
2015年 | 1542篇 |
2014年 | 2121篇 |
2013年 | 2642篇 |
2012年 | 3914篇 |
2011年 | 3902篇 |
2010年 | 1972篇 |
2009年 | 1844篇 |
2008年 | 3114篇 |
2007年 | 2999篇 |
2006年 | 2702篇 |
2005年 | 2676篇 |
2004年 | 2233篇 |
2003年 | 1995篇 |
2002年 | 1766篇 |
2001年 | 225篇 |
2000年 | 156篇 |
1999年 | 229篇 |
1998年 | 301篇 |
1997年 | 222篇 |
1996年 | 198篇 |
1995年 | 180篇 |
1994年 | 154篇 |
1993年 | 121篇 |
1992年 | 84篇 |
1991年 | 75篇 |
1990年 | 62篇 |
1989年 | 41篇 |
1988年 | 39篇 |
1987年 | 34篇 |
1986年 | 31篇 |
1985年 | 31篇 |
1984年 | 38篇 |
1983年 | 19篇 |
1982年 | 39篇 |
1981年 | 24篇 |
1980年 | 21篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 12篇 |
1976年 | 8篇 |
1972年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Mono- and bi-allelic expression of insulin-like growth factor II gene in human muscle tumors 总被引:4,自引:1,他引:3
Pedone Paolo V.; Tirabosco Roberto; Cavazzana Andrea O.; Ungaro Paola; Basso Giuseppe; Luksch Roberto; Carli Modesto; Bruni Carmelo B.; Frunzio Rodolfo; Riccio Andrea 《Human molecular genetics》1994,3(7):1117-1121
Insulin-like growth factor II (IGF-II) is a mitogen for manycell types and an important modulator of muscle growth and differentiation.IGF-II gene is prevalently expressed during prenatal developmentand its gene activity is regulated by genomic imprinting, inthat the allele inherited from the father is active and theallele inherited from the mother is inactive in most normaltissues. IGF-II expression is activated in several types ofhuman neoplasms and an alteration of IGF-II imprinting has beendescribed in BeckwithWiedemann syndrome and Wilms' tumour.Here we show that monoallelic expression of IGF-II gene is conservedin normal adult muscle tissue whereas two or more copies ofactive IGF-II alleles, arising by either relaxation of imprintingor duplication of the active allele, are found in 9 out of 11(82%) rhabdomyo-sarcomas retaining heterozygosity at 11p15,regardless of the histological subtype. Since IGF-II has beenindicated as an autocrine growth factor for rhabdomyosarcomacells, these findings strongly suggest that acquisition of adouble dosage of active IGF-II gene is an important step forthe initiation or progression of rhabdomyosarcoma tumorigenesis.Among different types of muscle tumors, relaxation of imprintingseems to arise prevalently in rhabdomyosarcomas, since we havedetected only one case of partial reactivation of the maternalIGF-II allele out of 7 lelomyosarcomas tested. 相似文献
82.
Thomas M. Gehring PhD Daniel Marti MS MD Andrea Sidler MA 《Child psychiatry and human development》1994,25(2):125-138
Perceptions of family cohesion and hierarchy structures were assessed by theFamily System Test (FAST), a clinically-derived figure placement technique. Parents (N=140) and their preadolescent offspring (N=70) completed typical and conflict representations in individual as well as group settings. Typical representations were characterized by balanced family structures (i.e. cohesive and moderately hierarchical) and those displaying conflict situations showed predominantly unbalanced patterns. FAST portrayals were related to respondent (mother vs. father vs. child). Fathers represented typical family relations as balanced more often than mothers. Regarding conflict representations, children were more likely than fathers to portray the family as unbalanced. However, analyses of representations of the same family (i.e. intra-family comparisons) indicated that all respondents differed in their perceptions and, that fathers' typical portrayals showed most often the same structure as those done by the family members as a group. 相似文献
83.
Andrea J Fradkin Peter A Cameron Belinda J Gabbe 《Journal of Science and Medicine in Sport》2007,10(1):66-71
Golfing injuries have been shown to occur frequently, and injury countermeasures have been suggested to help reduce injury risk. Performing an appropriate warm-up is thought to reduce injury risk, however there is a lack of evidence to support this notion. Therefore this study aimed to investigate the relationships between warm-up participation and injury in a cohort of female golfers. A total of 522 golfers participating in the Victorian Women's Pennant Competition completed the study. Over one-third (35.2%) of the golfers reported having sustained a golfing injury within the previous 12 months, with the lower back the most commonly injured region. Most golfers reported not warming-up prior to play or practice. Golfers who reported not warming-up on a regular basis were more likely to have reported a golfing injury in the previous 12 months than those reporting frequent warm-up participation (OR=45.2; 95% CI: 13.5, 151.7). Less skilled golfers were also less likely to report sustaining a golfing injury than more skilled golfers (OR=0.2; 95% CI: 0.1, 0.5). This study is one of the few to establish an association between warm-up participation and injury. Further prospective studies are warranted to determine whether warm-up reduces injury risk for golf participation. 相似文献
84.
85.
Angelo Pan Placido Mondello Klara Posfay-Barbe Patrizia Catenazzi Annise Grandi Silvia Lorenzotti Andrea Patroni Nadia Poli Laura Soavi Giuseppe Carnevale 《Infection control and hospital epidemiology》2007,28(9):1099-1102
In an Italian hospital, we observed that hand hygiene was performed in 638 (19.6%) of 3,253 opportunities, whereas gloves were worn in 538 (44.2%) 1,218 of opportunities. We observed an inverse correlation between the intensity of care and the rate of hand hygiene compliance (R2=0.057; P<.001), but no such association was observed for the rate of glove use compliance (R2=0.014; P=.078). Rates of compliance with hand hygiene and glove use recommendations follow different behavioral patterns. 相似文献
86.
Identification of the C-terminal flanking peptide of preprocholecystokinin in rat brain by a novel radioimmunoassay 总被引:1,自引:0,他引:1
The C-terminal flanking peptide of preprocholecystokinin (preproCCK) has been identified in extracts of rat brain using a novel radioimmunoassay. There is a single form of immunoreactive material on gel filtration, ion exchange and reversed-phase HPLC. The C-terminal preproCCK immunoreactivity had a similar pattern of distribution to CCK8 in different regions of rat brain. This assay should help in studies of neuronal CCK biosynthesis. 相似文献
87.
Andrea Frudinger Research Registrar Clive I. Bartram Consultant John A. D. Spencer Consultant Michael A. Kamm Consultant 《BJOG : an international journal of obstetrics and gynaecology》1997,104(9):1009-1013
Objective To assess the relation between perineal inspection and sphincter integrity in parous women.
Design Prospective observational study.
Setting District general hospital.
Population Fifty-seven consecutive parous women attending a gynaecology clinic for problems unrelated to the pelvic floor.
Methods A detailed history of bowel function and mode of delivery obtained; the perineum inspected to determine the presence and position of scarring, and anal endosonography performed.
Results In 19 women with an intact perineum on inspection, endosonography showed perineal scarring in five, with both perineal and sphincter scarring in three. Four had urge faecal incontinence. Three patients had a perineal tear only on inspection, but this group was too small for analysis and was discounted. Nine had an episiotomy scar only. Endosonography demonstrated perineal scarring in four, and combined perineal and sphincter scarring in two; one woman in this group had urge faecal incontinence. Twenty-six women had episiotomy and perineal tears on inspection. Endosonography revealed underlying perineal scarring in five women, with combined perineal and sphincter scarring in 14; six women in this group had urge faecal incontinence and one passive incontinence for flatus. Sonographically the scarring was anterior and circumferential rather than radial, and mostly left-sided, whereas on inspection episiotomy and perineal scarring were right sided.
Conclusions A normal perineum on clinical examination does not exclude underlying sphincter damage. The incidence of sphincter damage increases significantly when an episiotomy scar is associated with a perineal tear. 相似文献
Design Prospective observational study.
Setting District general hospital.
Population Fifty-seven consecutive parous women attending a gynaecology clinic for problems unrelated to the pelvic floor.
Methods A detailed history of bowel function and mode of delivery obtained; the perineum inspected to determine the presence and position of scarring, and anal endosonography performed.
Results In 19 women with an intact perineum on inspection, endosonography showed perineal scarring in five, with both perineal and sphincter scarring in three. Four had urge faecal incontinence. Three patients had a perineal tear only on inspection, but this group was too small for analysis and was discounted. Nine had an episiotomy scar only. Endosonography demonstrated perineal scarring in four, and combined perineal and sphincter scarring in two; one woman in this group had urge faecal incontinence. Twenty-six women had episiotomy and perineal tears on inspection. Endosonography revealed underlying perineal scarring in five women, with combined perineal and sphincter scarring in 14; six women in this group had urge faecal incontinence and one passive incontinence for flatus. Sonographically the scarring was anterior and circumferential rather than radial, and mostly left-sided, whereas on inspection episiotomy and perineal scarring were right sided.
Conclusions A normal perineum on clinical examination does not exclude underlying sphincter damage. The incidence of sphincter damage increases significantly when an episiotomy scar is associated with a perineal tear. 相似文献
88.
Data on the prevalence of antibody to hepatitis C virus among 278 subjects in an institution for the mentally handicapped were analysed by risk factors. A prevalence of 4% was found, higher than blood donors belonging to the same area (1.4%). No differences in prevalence with regard the length of residence, age, sex, degree of retardation or for presence of HBV markers were observed. 相似文献
89.
Idarubicin metabolism and pharmacokinetics after intravenous and oral administration in cancer patients: a crossover study 总被引:1,自引:0,他引:1
Carlo M. Camaggi Elena Strocchi Patrizia Carisi Andrea Martoni Alessandra Tononi Monica Guaraldi Margherita Strolin-Benedetti Constantin Efthymiopoulos Franco Pannuti 《Cancer chemotherapy and pharmacology》1992,30(4):307-316
The pharmacokinetics and metabolism of 4-demethoxydaunorubicin (idarubicin, IDA) were studied in 21 patients with advanced cancer after i.v. (12 mg/m2) and oral (30-35 mg/m2) treatment according to a balanced crossover design. Patients were divided into four groups: subjects who showed normal liver and kidney function (group N), those who presented with normal kidney function and liver metastases (group L), those with kidney dysfunction (creatinine clearance, less than or equal to 60 l/h; group R), and those with both liver and kidney dysfunction (group LR). Five patients showed variations in liver or kidney function after the first treatment and were considered to be nonevaluable for the crossover study but evaluable for the liver/kidney function study; some of them appeared in different groups for the i.v. as opposed to p.o. treatments. After i.v. administration, IDA plasma levels followed a triphasic decay pattern. The main metabolite observed in all patients was the 13C-reduced compound (IDAol), which attained plasma levels 2-12 times higher than those of the parent compound. IDA pharmacokinetics was not dependent on the presence of liver metastases but was related to the integrity of kidney function. Analysis of variance indicated a significant correlation between IDA plasma clearance and creatinine clearance; it was also found that IDA plasma clearance was lower in patients whose creatinine clearance was less than 60 ml/min [group N, 122.8 +/- 44.0 l/h; group L, 104.4 +/- 27.7 l/h (P = 0.58) vs group R, 83.4 +/- 18.3 l/h (P = 0.037)]. The IDAol terminal half-life and mean residence time (MRT) were significantly increased in patients with impaired kidney function [MRT: group N, 63.6 +/- 10.8 h; group L, 69.9 +/- 10.2 h (P = 0.27) vs group R, 83.2 +/- 10.9 h (P = 0.025) and t1/2 gamma: group N, 41.3 +/- 10.1 h; group L, 47.0 +/- 7.4 h (P = 0.31) vs group R, 55.8 +/- 8.2 h (P = 0.025)]. After oral treatment, drug absorption occurred during in the first 2-4 h after IDA administration; a biphasic decay pattern was observed thereafter. The main metabolite observed in all patients was again IDAol. The AUC of IDAol was greater after oral administration than after i.v. treatment in proportion to the AUC of IDA (i.v.: AUC-IDAol/AUC-IDA, 2.4-18.9; p.o.: AUC-IDAol/AUC-IDA, 4.1-21.4). Following oral dosing, a substantial amount of 4-demethoxydaunomycinone (AG1) was found in 11/21 patients.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
90.
Reducing the Occupational Risk of Infections for the Surgeon: Multicentric National Survey on More Than 15,000 Surgical Procedures 总被引:2,自引:0,他引:2
Andrea Pietrabissa Stefano Merigliano Marco Montorsi Gilberto Poggioli Marco Stella Domenico Borzomati Enrico Ciferri Giuseppe Rossi Gianbattista Doglietto 《World journal of surgery》1997,21(6):573-578
The objective of this study was to find the incidence of accidental exposures to blood and body fluids among surgeons during operations and to describe their dynamics. A probabilistic model was also used to predict the cumulative 30-year risk to the surgeon of contracting hepatitis B and C viruses (HBV, HCV) or human immunodeficiency virus (HIV) infection and estimate the effect of preventive strategies in reducing this risk. A multicentric prospective survey, based on self-administered questionnaires, was conducted during a period of 6 months in 39 Italian hospitals. An accidental exposure to blood or body fluids occurred in 9.2% of 15,375 operations. In about 2% of procedures a parenteral-type injury, such as actual skin puncture or eye contamination, was suffered by the operating surgeon. A needle-stick injury was the commonest accident, and its occurrence was found to vary with the phase of the procedure and its length. The current lifetime risk of acquiring HBV, HCV, and HIV infection in our regions was estimated to be as high as 42.7%, 34.8%, and 0.54%, respectively. The adoption of preventive strategies is expected to reduce this risk to 21% for HBV, 16.6% for HCV, and 0.23% for HIV infection. Active immunization of surgeons against HBV is strongly recommended. The case is also made for the use of a face-shield combined with a permanent change in our surgical practice capable of reducing the current high rate of parenteral injuries. 相似文献