全文获取类型
收费全文 | 2822篇 |
免费 | 234篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 61篇 |
妇产科学 | 42篇 |
基础医学 | 338篇 |
口腔科学 | 60篇 |
临床医学 | 322篇 |
内科学 | 448篇 |
皮肤病学 | 67篇 |
神经病学 | 322篇 |
特种医学 | 106篇 |
外科学 | 409篇 |
综合类 | 35篇 |
预防医学 | 404篇 |
眼科学 | 47篇 |
药学 | 148篇 |
中国医学 | 2篇 |
肿瘤学 | 234篇 |
出版年
2021年 | 43篇 |
2019年 | 42篇 |
2018年 | 50篇 |
2017年 | 38篇 |
2016年 | 33篇 |
2015年 | 45篇 |
2014年 | 59篇 |
2013年 | 84篇 |
2012年 | 104篇 |
2011年 | 124篇 |
2010年 | 77篇 |
2009年 | 56篇 |
2008年 | 125篇 |
2007年 | 130篇 |
2006年 | 139篇 |
2005年 | 122篇 |
2004年 | 93篇 |
2003年 | 132篇 |
2002年 | 96篇 |
2001年 | 110篇 |
2000年 | 88篇 |
1999年 | 87篇 |
1998年 | 35篇 |
1997年 | 25篇 |
1996年 | 26篇 |
1995年 | 39篇 |
1994年 | 23篇 |
1993年 | 24篇 |
1992年 | 53篇 |
1991年 | 54篇 |
1990年 | 57篇 |
1989年 | 67篇 |
1988年 | 49篇 |
1987年 | 52篇 |
1986年 | 50篇 |
1985年 | 47篇 |
1984年 | 36篇 |
1983年 | 38篇 |
1982年 | 25篇 |
1981年 | 23篇 |
1979年 | 33篇 |
1978年 | 35篇 |
1977年 | 22篇 |
1974年 | 21篇 |
1973年 | 27篇 |
1972年 | 22篇 |
1971年 | 27篇 |
1969年 | 25篇 |
1968年 | 22篇 |
1966年 | 27篇 |
排序方式: 共有3059条查询结果,搜索用时 10 毫秒
21.
Harold B. Canning DDS David E. Frost DDS MS Daniel K. McDonald DDS Robert W. Joyner MD 《Journal of oral and maxillofacial surgery》1988,46(12):1048-1050
In a double-blind, randomized plan of drug administration, nalbuphine, fentanyl, and a placebo were compared for efficacy in sedation and analgesia during third molar removal. Fifty-eight patients participated in this study. Using accepted intravenous sedation and surgical techniques, fentanyl and nalbuphine were found to be better than placebo for anxiety and pain control in third molar surgery. Fentanyl had a longer duration of pain relief postoperatively than did nalbuphine. The study confirmed the need for a narcotic supplement to sedation techniques for third molar surgery. 相似文献
22.
H M Frost 《The Anatomical record》1990,226(4):423-432
A chondral growth/force response curve predicts how intact hyaline cartilage plates grow in vivo under typical peak mechanical unit loads and gradients thereof in healthy immature mammals. Growth under tension would increase as tension rises from zero to a level that damages the tissue. Under compression, growth would increase as the load rises from zero to a level at which growth becomes maximal (the growth-ascending limb of the curve). Further increases in compression loads retard growth and large enough increases can stop it entirely (the growth-descending limb of the curve). For equal changes in loads, the smallest growth change would occur under tension; the largest change would occur on the growth-descending part of the curve. Under zero load a respectable "baseline growth" still occurs. Those effects are superimposed on inherent differences in growth potential of different chondral plates, differences that are determined partly in utero and by the genome. The curve's features can explain many anatomical facts, including the ball-and-socket ankle, joint alignment in the valgus-varus sense, hip dislocations in spasticity, different epiphyseal heights, short bones in paralysed limbs, long bone overgrowth after fractures, why some joint surfaces remain concave and others convex throughout growth, and why some growth plates are domed instead of flat. The above phenomena can be expressed mathematically, and a phenomenologic basic logical framework for doing that is suggested. 相似文献
23.
Skeletal structural adaptations to mechanical usage (SATMU): 1. Redefining Wolff's law: the bone modeling problem 总被引:11,自引:0,他引:11
H M Frost 《The Anatomical record》1990,226(4):403-413
From the nature of a bone's endload and its local surface strains, the theory computes a modeling operator, Gamma (gamma), that predicts whether mechanical factors will cause lamellar bone modeling drifts, and where and of what kind. A given mechanical bone strain history then provides a separate modeling rate function, M, to specify the rate of such modeling drifts as fractions of the largest possible ones. Multiplying the two functions, e.g., gamma.M, then predicts mechanically controlled bone modeling responses for cortical and trabecular bone, both quantitatively and qualitatively. The theory correctly predicts each of the 6 known "principal adaptations" of lamellar bone, which provide a critical test of any such theory for this organ. The theory accounts for biologic, biomechanical, and clinical-pathologic knowledge not available in Wolff's time nor accounted for by most biomechanicians since. Existing proven methods can provide all numerical data needed to satisfy the theory's mathematical equations and already suggest provisional values for most of them. Its originator views the theory as the kernel of more and better theories to come rather than a finished work, a kernel that suggests a new and in some respects novel logical framework for analysing the problems, and a kernel that invites critique, refinement, and/or exploitation by others. 相似文献
24.
Eileen Mary Grealish Robert P. Hawkins Pamela Meadowcroft Pamela Weaver Sharon S. Frost Percilla Lynch 《Child & youth care forum》1989,18(1):49-61
Many youth, their parents, and social services regard the unification of the family as the most desirable outcome for youth in out-of-home placements. This goal is often difficult to achieve because the families of these troubled/troubling youths are often severely dysfunctional, with multiple problems. A group process model for serving natural parents of youth in placement is described which, in conjunction with one-on-one interactions with professionals, appears to have a positive impact on these families and on youths' return home. Group components that seem particularly important are described, including attendance by invitation only, public commitment to attend and participate, reminder prompts, transportation support, babysitting support, refreshments, opportunity to visit with their child, defined staff roles, an empowering approach, and starting where the parent is. The group process maintained a relatively high level of both attendance and participation by the targeted parents. Participants tended to achieve most goals that they set in the group. Our experience indicates that interventions with natural parents of troubled youth can enable even a very dysfunctional family to improve enough to receive youth back into their home.The authors are grateful for the assistance of Sharon Estill, Jim Bernardo, Anita Mentzer, Dave Walker, and Suni Dague-Lyman for assistance in collecting the data reported here. Debbie Buchanan and others have been a great assistance in transporting families. 相似文献
25.
26.
The authors investigated factors that predict intention to take a genetic test for Alzheimer's disease (AD). The 449 men and women were surveyed in two groups: (a) those told that a positive result meant a 90% chance of developing AD (increased certainty) and (b) those told that a positive result meant a 50% chance of developing AD (decreased certainty). Participants completed measures of the Theory of Planned Behavior (TPB), anticipated regret, risk perception, likelihood of taking a genetic test for cancer, and AD risk factors. Just over 50% of the variance in intentions was related to TPB variables, likelihood of taking a genetic test for cancer, number of people the participants knew who had AD, experimental condition, and anticipated regret. The subjective norm was the strongest predictor of intention in the increased certainty group, whereas positive belief was the strongest predictor in the decreased certainty group. 相似文献
27.
Fluorescent amplified fragment length polymorphism genotyping of Campylobacter jejuni and Campylobacter coli strains and its relationship with host specificity, serotyping, and phage typing 总被引:4,自引:0,他引:4 下载免费PDF全文
Fluorescent amplified fragment length polymorphism (FAFLP) analysis was applied to 276 Campylobacter jejuni strains and 87 Campylobacter coli strains isolated from humans, pigs, cattle, poultry, and retail meats to investigate whether certain FAFLP genotypes of C. jejuni and C. coli are associated with a particular host and to determine the degree of association between FAFLP-defined genotypes and heat-stable serotypes and/or phage types. Within C. coli, the poultry strains clustered separately from those of porcine origin. In contrast, no evidence of host specificity was detected among C. jejuni strains. While C. coli strains show host specificity by FAFLP genotyping, C. jejuni strains that are genotypically similar appear to colonize a range of hosts, rather than being host adapted. Some serotypes and/or phage types (C. jejuni serotype HS18, phage type PT6, and serophage type HS19/PT2 and C. coli HS66, PT2, and HS56/PT2) were the most homogeneous by FAFLP genotyping, while others were more heterogeneous (C. jejuni HS5 and PT39, and C. coli HS24 and PT44) and therefore poor indicators of genetic relatedness between strains. The lack of host specificity in C. jejuni suggests that tracing the source of infection during epidemiological investigations will continue to be difficult. The lack of congruence between some serotypes and/or phage types and FAFLP genotype underlines the need for phenotypic testing to be supplemented by genotyping. This study also demonstrates how, in general, FAFLP generates "anonymous" genetic markers for strain characterization and epidemiological investigation of Campylobacter in the food chain. 相似文献
28.
von Grünau M. Frost B. J. 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1983,49(1):84-92
Summary For the experiments reported in this study, recordings were obtained from 246 single units in the middle lateral suprasylvian visual area (LS) of 13 cats. 49 of these cells were subjected to detailed quantitative analysis. The receptive field (RF) organization was examined for directionally specific cells by presenting moving single spots on large moving random dot backgrounds. A cell's response to an optimal spot (in terms of size, direction, velocity) moving on a stationary background inside the excitatory RF (ERF) was compared to in-phase (same direction, same velocity) and anti-phase (opposite direction, same velocity) movement of spot and background. In-phase movement resulted in inhibition of the cell's response (3–100%) in 94% of the cells, while anti-phase movement led to reduced inhibition in 52% of the cells or to facilitation (0.5–327%) in 39% of the cells. By changing the direction of background motion with respect to that of the spot, the directional tuning of the in-phase inhibition and anti-phase facilitation effects was determined.We were able to manipulate the size of the background effects by masking out the background for various proportions of the ERF, and maximizing them by restricting background stimulation to the large inhibitory RF (IRF) surrounding the ERF. These results could be best accounted for by a double-opponent-process mechanism with both RF center and RF surround being directionally selective, but with opposite polarity. It is suggested that this type of mechanism could be involved in the processing of object motion.Partially supported by an NSERC University Research Fellowship (U 0057) and an ARC equipment grant to M. von Grünau and by an NSERC Grant to B. J. Frost (A 0353) 相似文献
29.
Tyrer P Thompson S Schmidt U Jones V Knapp M Davidson K Catalan J Airlie J Baxter S Byford S Byrne G Cameron S Caplan R Cooper S Ferguson B Freeman C Frost S Godley J Greenshields J Henderson J Holden N Keech P Kim L Logan K Manley C MacLeod A Murphy R Patience L Ramsay L De Munroz S Scott J Seivewright H Sivakumar K Tata P Thornton S Ukoumunne OC Wessely S 《Psychological medicine》2003,33(6):969-976
BACKGROUND: We carried out a large randomized trial of a brief form of cognitive therapy, manual-assisted cognitive behaviour therapy (MACT) versus treatment as usual (TAU) for deliberate self-harm. METHOD: Patients presenting with recurrent deliberate self-harm in five centres were randomized to either MACT or (TAU) and followed up over 1 year. MACT patients received a booklet based on cognitive behaviour therapy (CBT) principles and were offered up to five plus two booster sessions of CBT from a therapist in the first 3 months of the study. Ratings of parasuicide risk, anxiety, depression, social functioning and global function, positive and negative thinking, and quality of life were measured at baseline and after 6 and 12 months. RESULTS: Four hundred and eighty patients were randomized. Sixty per cent of the MACT group had both the booklet and CBT sessions. There were seven suicides, five in the TAU group. The main outcome measure, the proportion of those repeating deliberate self-harm in the 12 months of the study, showed no significant difference between those treated with MACT (39%) and treatment as usual (46%) (OR 0.78, 95% CI 0.53 to 1.14, P=0.20). CONCLUSION: Brief cognitive behaviour therapy is of limited efficacy in reducing self-harm repetition, but the findings taken in conjunctin with the economic evaluation (Byford et al. 2003) indicate superiority of MACT over TAU in terms of cost and effectiveness combined. 相似文献
30.
Summary We examined the specificity and developmental time course of the labelling of retinal ganglion cells in Syrian hamsters by a monoclonal antibody AB5. In adult hamsters, AB5 selectively labelled somata in the ganglion cell layer, dendrites in the inner plexiform layer and axons in the nerve fibre layer. When retinal ganglion cells were retrogradely labelled with Dil prior to AB5 immunocytochemistry, all of the retrogradely labelled retinal ganglion cells in the ganglion cell layer were AB5 immunoreactive, indicating that AB5 labels all classes of ganglion cell in that layer. In retinae depleted of retinal ganglion cells by neonatal optic nerve transections, AB5 did not label any somata or processes, indicating that AB5 specifically labels retinal ganglion cells. During development, AB5 labelling first appeared as a weak staining of cell bodies in the ganglion cell layer on postnatal day 12 (P12; PO=first 24 h following birth) and acquired the staining pattern seen in the adult by postnatal day 14. From the onset of AB5 immunoreactivity, AB5-labelled somata of varying sizes were present across the entire retinal surface. Although AB5 labelled retinal ganglion cell axons in the nerve fibre layer of the retina it did not label the optic nerve or retinal ganglion cell axons in the brain at any age examined. AB5 labelling was also found to be compatible with bromodeoxyuridine immunocytochemistry and, therefore, useful for determining the time of generation of hamster retinal ganglion cells. 相似文献