全文获取类型
收费全文 | 611篇 |
免费 | 26篇 |
国内免费 | 42篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 20篇 |
妇产科学 | 1篇 |
基础医学 | 59篇 |
口腔科学 | 15篇 |
临床医学 | 69篇 |
内科学 | 169篇 |
皮肤病学 | 4篇 |
神经病学 | 9篇 |
特种医学 | 194篇 |
外科学 | 17篇 |
综合类 | 17篇 |
预防医学 | 53篇 |
眼科学 | 1篇 |
药学 | 23篇 |
中国医学 | 1篇 |
肿瘤学 | 23篇 |
出版年
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 21篇 |
2014年 | 15篇 |
2013年 | 19篇 |
2012年 | 16篇 |
2011年 | 15篇 |
2010年 | 15篇 |
2009年 | 17篇 |
2008年 | 9篇 |
2007年 | 37篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 9篇 |
1998年 | 34篇 |
1997年 | 33篇 |
1996年 | 36篇 |
1995年 | 30篇 |
1994年 | 46篇 |
1993年 | 24篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 34篇 |
1988年 | 34篇 |
1987年 | 33篇 |
1986年 | 22篇 |
1985年 | 19篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 4篇 |
排序方式: 共有679条查询结果,搜索用时 187 毫秒
161.
The objective of this study was to describe trends in neonatal meningitis in England and Wales during the years 1975-91. Laboratory reports and, for the years 1983-91, data on statutory notifications and deaths from neonatal meningitis were reviewed. The mean annual total of laboratory reports of neonatal bacterial meningitis 1975-91 was 109 cases (range 69-133) with a slight upward trend apparent in the latter half of the study period. The mean annual number of reports of neonatal viral meningitis was only 14 cases with no trend apparent. The leading bacteria isolated were group B streptococci, Escherichia coli, and Listeria monocytogenes accounting for 34.1%, 28.5%, and 6.8% of reports, respectively. There was a change in the pattern of causative bacteria from 1981 onwards with the group B streptococcus displacing E coli as the leading cause. With respect to neonatal viral meningitis, echoviruses and coxsackie viruses accounted for 55.4% and 38.6% of cases, respectively. Neonatal meningitis was seriously undernotified; the ratio of laboratory reported cases to cases notified ranged from 12:1 in 1985 to 4:1 in 1989. The annual numbers of deaths ranged from 18 to 39. The laboratory reporting system provided the most useful data on secular trends and causative organisms for neonatal meningitis. The slight upward trend in the number of reports of bacterial meningitis merits continued surveillance. 相似文献
162.
DL Kennaird 《Archives of disease in childhood》1976,51(1):34-41
The relation between environmental temperature, heat production, oxygen consumption, and evaporative water loss was studied in 67 infants with congenital heart disease. The majority of the cyanosed infants had a low minimum oxygen consumption, a low evaporative water loss, and a diminished metabolic response to cold stress. Minimum oxygen consumption and evaporative water loss rose in 6 of these infants after the construction of a surgical shunt. Many of the ill acyanotic infants had an abnormally high minimum oxygen consumption, and those in cardiac failure often continued to sweat in an environment below the thermoneutral temperature zone. 相似文献
163.
164.
Buckeridge DL Mason R Robertson A Frank J Glazier R Purdon L Amrhein CG Chaudhuri N Fuller-Thomson E Gozdyra P Hulchanski D Moldofsky B Thompson M Wright R 《Social science & medicine (1982)》2002,55(7):1189-1206
This paper presents the main findings from a collaborative community/university research project in Canada. The goal of the project was to improve access to community health information, and in so doing, enhance our knowledge of the development of community health information resources and community/university collaboration. The project built on a rich history of community/university collaboration in Southeast Toronto (SETO), and employed an interdisciplinary applied research and action design. Specific project objectives were to: (1) develop via active community/university collaboration a geographic information system (GIS) for ready access to routinely collected health data, and to study logistical, conceptual and technical problems encountered during system development; and (2) to document and analyze issues that can emerge in the process of community/university research collaboration. System development involved iteration through community user assessment of need, development or refinement of the GIS, and assessment of the GIS by community users. Collaborative process assessment entailed analysis of archival material, interviews with investigators and participant observation. Over the course of the project, a system was successfully developed, and favorably assessed by users. System development problems fell into four main areas: maintaining user involvement in system development, understanding and integrating data, bringing disparate data sources together, and making use of assembled data. Major themes emerging from the community/university collaborative research process included separate community and university cultures, time as an important issue for all involved, and the impact of uncertainty and ambiguity on the collaborative process. 相似文献
165.
166.
TL Carter CH Cole CF Mews PJ Price DL Baker 《Journal of paediatrics and child health》1997,33(3):238-241
Objective: To assess the prevalence of hepatitis C in 200 patients with paediatric malignancies, surviving in remission more than 5 years from diagnosis, who had received blood product transfusions before 1990 when routine screening of blood products for hepatitis C began.
Method: The second and third generation Abbott Diagnostics ELISA was used to assess hepatitis C seropositivity. Seropositive patients and those with abnormal liver transaminases were assessed by hepatitis C virus RNA polymerase chain reaction (PCR).
Results: A low incidence (4%) of seropositivity for hepatitis C was found in survivors of paediatric malignancy who were transfused prior to routine screening of blood products in this cohort.
Conclusions: All patients identified have evidence of hepatitis and may be at high risk of developing cirrhosis. 相似文献
Method: The second and third generation Abbott Diagnostics ELISA was used to assess hepatitis C seropositivity. Seropositive patients and those with abnormal liver transaminases were assessed by hepatitis C virus RNA polymerase chain reaction (PCR).
Results: A low incidence (4%) of seropositivity for hepatitis C was found in survivors of paediatric malignancy who were transfused prior to routine screening of blood products in this cohort.
Conclusions: All patients identified have evidence of hepatitis and may be at high risk of developing cirrhosis. 相似文献
167.
Encouraging survival and tumour marker results have been described in patients where the focally destructive technique, hepatic cryotherapy, is used to treat primary and secondary hepatic malignancy. Radiology allows assessment of the cryotherapy procedure and follow-up treatment. This paper aims to review and describe the appearance of hepatic cryotherapy by CT. 相似文献
168.
Dietary energy restriction was previously shown to be effective in
preventing a wide range of experimentally induced cancers. Studies were
conducted to assess the influence on pancreatic carcinogenesis of dietary
energy restrictions (reduced fat and carbohydrate) of 10%, 20% or 40% in
comparison with control in Syrian hamsters treated with N-
nitrosobis(2-oxopropyl)amine (BOP). Two carcinogenesis studies were
conducted. One used a single treatment with 20 mg BOP/kg body weight and
followed hamsters for 102 weeks following treatment, and the other used
three weekly treatments of 20 mg BOP/kg body weight and followed hamsters
for 45 weeks after treatment. Hamsters were fed control or energy
restricted diet beginning the week following the last BOP treatment.
Pancreatic carcinomas were induced in 9-18% of the hamsters in the first
experiment and in 59-66% of the animals in the second. Dietary energy
restriction did not influence carcinoma incidence in either study, and in
the second experiment the multiplicity of tumors was higher in the 40%
energy restriction (ER) group than in control hamsters. Plasma
corticosterone was suppressed by BOP treatment, particularly in the 20% and
40% ER hamsters in the second experiment, and diet or BOP treatment did not
significantly alter plasma cortisol. Pancreatic protein kinase Czeta
measured by Western blot was highest in the cytosol and particulate
fractions of the 40% ER hamsters in the first experiment. These results
indicate that dietary energy restriction is not effective in the prevention
of BOP induced pancreatic carcinogenesis in the Syrian hamster.
相似文献
169.
McCormick DL; Ryan BM; Findlay JC; Gauger JR; Johnson TR; Morrissey RL; Boorman GA 《Carcinogenesis》1998,19(9):1649-1653
The results of a number of epidemiology studies suggest that exposure to
power frequency (50 and 60 Hz) magnetic fields may be a risk factor for
hematopoietic neoplasia. To generate experimental data to test this
hypothesis, the influence of magnetic field exposure on lymphoma induction
was determined in two strains of mice that are genetically predisposed to
the disease. PIM mice, which carry the pim-1 oncogene, are highly sensitive
to lymphoma induction by N-ethyl-N-nitrosourea (ENU); ENU-treated PIM mice
were studied as a 'high incidence' lymphoma model. TSG-p53 (p53 knockout)
mice, in which the p53 tumor suppressor gene has been deleted from the germ
line, develop lymphoma as an age- related change; hemizygous TSG-p53 mice
were studied as a 'low incidence' lymphoma model. Beginning 1 day after a
single i.p. injection of 25 mg ENU/kg body wt, groups of 30 PIM mice/sex
were exposed for 18.5 h/day to pure, linearly polarized, transient-free 60
Hz magnetic fields at field strengths of 0 (sham control), 0.02, 2.0 or
10.0 Gauss (G). An additional group of 30 PIM mice/sex was exposed
intermittently (1 h on, 1 h off) to 10.0 G fields. Groups of 30 TSG-p53
mice/sex were exposed continuously to magnetic field strengths of 0 (sham
control) or 10.0 G; TSG-p53 mice received no ENU. Studies were terminated
after 23 weeks of magnetic field exposure. Lymphoma incidence in male PIM
mice exposed continuously to 10.0 G magnetic fields was significantly
reduced from that seen in sex-matched sham controls; survival, lymphoma
incidence and lymphoma latency in other groups of PIM mice did not differ
from sham controls. Survival and lymphoma incidence in all groups of
TSG-p53 mice was 7% or less, regardless of magnetic field exposure regimen.
These data do not support the hypothesis that exposure to magnetic fields
is a significant risk factor for lymphoid neoplasia in mice with a genetic
predisposition to the disease.
相似文献
170.
Eichler EE; Macpherson JN; Murray A; Jacobs PA; Chakravarti A; Nelson DL 《Human molecular genetics》1996,5(3):319-330
To understand the origins of the fragile X syndrome and factors
predisposing alleles to instability and hyperexpansion, we have compared
the haplotype (using markers FRAXAC1, FRAXAC2, and DXS548) and AGG
interspersion patterns of the FMR1 CGG repeat for 214 normal and 16
premutation chromosomes. Association testing between interspersion pattern
and haplotype reveals a highly significant (P < 0.002) non- random
distribution, indicating that all three markers are useful in phylogenetic
reconstruction of mutational change. Parsimony analysis of the FMR1 CGG
repeat substructure predicts that loss of AGG interruptions has occurred
independently on many haplotypes associated with the fragile X syndrome,
partially explaining the haplotype diversity of this disease. Among
haplotypes found in linkage disequilibrium with the fragile X mutation, two
different modes of mutation and predisposition to instability have been
identified. One pathway has involved the frequent and recurrent loss of AGG
interruptions from rare asymmetrical ancestral array structures.
Intergenerational transmission studies suggest that these predisposed
chromosomes progress relatively rapidly to the disease state. In contrast,
the second mutational pathway involves a single haplotype which has
maintained two AGG interruptions. Parsimony analysis of CGG repeat
substructure within this haplotype suggests that larger alleles have been
generated by gradual increments of CGG repeats distal to the most 3'
interruption. Pedigree analysis of the intergenerational stability of
alleles of this haplotype confirms a gradual progression toward instability
thresholds. As a result, a large reservoir of chromosomes carrying large
repeats on this haplotype exists. These chromosomes are predisposed to
disease. The present data support a model in which there are at least two
different mutational pathways predisposing alleles to instability and
hyperexpansion associated with the fragile X syndrome.
相似文献