全文获取类型
收费全文 | 4001篇 |
免费 | 313篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 17篇 |
儿科学 | 70篇 |
妇产科学 | 36篇 |
基础医学 | 569篇 |
口腔科学 | 25篇 |
临床医学 | 364篇 |
内科学 | 1224篇 |
皮肤病学 | 69篇 |
神经病学 | 436篇 |
特种医学 | 93篇 |
外科学 | 660篇 |
综合类 | 40篇 |
预防医学 | 284篇 |
眼科学 | 24篇 |
药学 | 184篇 |
中国医学 | 8篇 |
肿瘤学 | 229篇 |
出版年
2023年 | 26篇 |
2022年 | 50篇 |
2021年 | 117篇 |
2020年 | 60篇 |
2019年 | 108篇 |
2018年 | 130篇 |
2017年 | 99篇 |
2016年 | 77篇 |
2015年 | 91篇 |
2014年 | 119篇 |
2013年 | 161篇 |
2012年 | 252篇 |
2011年 | 257篇 |
2010年 | 137篇 |
2009年 | 150篇 |
2008年 | 219篇 |
2007年 | 196篇 |
2006年 | 187篇 |
2005年 | 200篇 |
2004年 | 172篇 |
2003年 | 169篇 |
2002年 | 154篇 |
2001年 | 105篇 |
2000年 | 95篇 |
1999年 | 100篇 |
1998年 | 35篇 |
1997年 | 32篇 |
1996年 | 40篇 |
1995年 | 36篇 |
1994年 | 21篇 |
1993年 | 24篇 |
1992年 | 75篇 |
1991年 | 59篇 |
1990年 | 66篇 |
1989年 | 53篇 |
1988年 | 65篇 |
1987年 | 64篇 |
1986年 | 49篇 |
1985年 | 48篇 |
1984年 | 38篇 |
1983年 | 22篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 22篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1975年 | 13篇 |
1974年 | 15篇 |
1973年 | 12篇 |
1972年 | 11篇 |
排序方式: 共有4332条查询结果,搜索用时 15 毫秒
1.
Nickel Allergy and Our Children's Health: A Review of Indexed Cases and a View of Future Prevention 下载免费PDF全文
Sharon E. Jacob M.D. Alina Goldenberg M.D. M.A.S. Janice L. Pelletier M.D. Luz S. Fonacier M.D. Richard Usatine M.D. Nanette Silverberg M.D. 《Pediatric dermatology》2015,32(6):779-785
Nickel is the leading cause of allergic contact dermatitis (ACD) from early childhood through adolescence. Studies have shown that skin piercings and other nickel‐laden exposures can trigger the onset of nickel ACD in those who are susceptible. Nickel ACD causes a vast amount of cutaneous disease in children. Cases of nickel ACD in children have been reported in peer‐reviewed literature from 28 states. Common items that contain inciting nickel include jewelry, coins, zippers, belts, tools, toys, chair studs, cases for cell phones and tablets, and dental appliances. The diagnosis of nickel ACD has been routinely confirmed by patch testing in children older than 6 months suspected of ACD from nickel. Unlike in Europe, there are no mandatory restrictions legislated for nickel exposure in the United States. Denmark has demonstrated that regulation of the nickel content in metals can lower the risk of ACD and the associated health care–related costs that arise from excess nickel exposure. To further awareness, this article reviews the prominent role of nickel in pediatric skin disease in the United States. It discusses the need for a campaign by caretakers to reduce nickel‐related morbidity. Lastly, it promotes the model of European legislation as a successful intervention in the prevention of nickel ACD. 相似文献
2.
M. J. Englesbe S. J. Pelletier S. Kheterpal M. O'Reilly D. A. Campbell Jr. 《American journal of transplantation》2006,6(4):666-670
The severity of illness in transplant patients and the complexity of transplant operations results in significant postoperative morbidity and mortality. Remarkable efforts have been made by transplant physicians to study and improve organ allocation, graft and patient survival, immunosuppression and the long-term management of post-transplant complications. Less effort has been spent studying the actual transplant operation and systems of acute transplant care. The National Surgical Quality Improvement Program (NSQIP) has provided a standardized approach to quality improvement and has demonstrated significant potential for a reduction in postoperative morbidity and mortality in other surgical disciplines. Medical centers are under increasing pressure to measure surgical quality and the nexus of transplant surgical quality improvement should not lie in the hands of CMS or JACHO, but rather it should be created and developed within the transplant community. The time has come for a national transplant surgical quality improvement program based on the NSQIP infrastructure. Such a proactive approach toward quality improvement from the transplant community is an excellent investment for patients, providers and health care payers. 相似文献
3.
Martin Lepage Karine Sergerie Marc Pelletier Philippe-Olivier Harvey 《Revue canadienne de psychiatrie》2007,52(11):702-709
Much of the research on episodic memory in schizophrenia spectrum disorders has focused on memory deficits and how they relate to clinical measures such as outcome. Memory bias refers to the modulatory influence that state or trait psychopathology may exert on memory performance for specific categories of stimuli, often emotional in nature. For example, subjects suffering from depression frequently have better memory for negative stimuli than for neutral or positive ones. This dimension of memory function has received only scant attention in schizophrenia research but could provide fresh new insights into the relation between symptoms and neurocognition. This paper reviews the studies that have explored memory biases in individuals with schizophrenia. With respect to positive symptoms, we examine studies that have explored the link between persecutory delusions and memory bias for threatening information and between psychosis and a memory bias toward external source memory. Although relatively few studies have examined negative symptoms, we also review preliminary evidence indicating that flat affect and anhedonia may lead to some specific emotional memory biases. Finally, we present recent findings from our group delineating the relation between emotional valence for faces and memory bias toward novelty and familiarity, both in schizophrenia patients and in healthy control subjects. A better understanding of the biasing effects of psychopathology on memory in schizophrenia (but also on other cognitive functions, such as attention, attribution, and so forth) may provide a stronger association between positive and negative symptoms and memory function. Memory measures sensitive to such biases may turn out to be stronger predictors of clinical and functional outcome. 相似文献
4.
G Pelletier A M de Passillé M Bernier-Cardou J Morisset 《The Journal of nutrition》1987,117(10):1759-1766
In the first experiment, 52 sows, each having raised one litter, were randomly assigned to the five following groups: control (nongravid) for pregnancy (CP), 110 d pregnancy (P110), control (nongravid) for lactation (CL), 4-wk lactation with 8 (L8) and with 12 (L12) piglets. In a second experiment, 36 sows, each having raised three litters, were randomly assigned to the following groups: control group (nongravid) fed a low-energy-density, 1% tallow diet (CLED) and two lactating groups, one fed the low-energy-density diet (LLED) and one fed a high-energy-density, 10% tallow diet (LHED). At slaughter, the stomach, small and large intestine and cecum were excised, emptied and freed from fat. Lengths and pre- and post-defatting weights were measured. Portions of tissues were homogenized and analyzed for protein, pepsin, maltase, RNA and DNA. Pregnancy had no effect on the weights of the different components of the gastrointestinal tract. Liver and small intestine weights were larger in lactating sows than in the CL group. Sows nursing 12 piglets had heavier livers than those nursing 8. The fundic mucosa of the latter had higher total pepsin activity and total protein and RNA contents than that of L12 sows. LHED sows had heavier small intestine and lower total pepsin content of the fundic mucosa than LLED sows. 相似文献
5.
6.
The influence of sex steroids and the dopaminergic system on the in vivo modulation of prolactin (PRL) mRNA levels was investigated by quantitative in situ hybridization in the male rat anterior pituitary gland. In situ hybridization was performed using a [35S]-labeled cDNA probe encoding PRL. Orchiectomy performed 14 days earlier did not modify PRL mRNA levels. In orchiectomized rats treatment with the dopaminergic agonist bromocriptine for 14 days decreased PRL mRNA levels by 30%, while in intact animals the same treatment did not induce any changes in PRL mRNA levels. Administration of the dopamine D2 receptor antagonist haloperidol in both intact and orchiectomized rats induced a 4-fold increase in mRNA levels. Administration of dihydrotestosterone to orchiectomized animals which had been treated or not with haloperidol or bromocriptine did not modify PRL mRNA levels. In orchiectomized animals administration of 17ß-estradiol (0.25 μg twice daily) for 14 days caused a 4-fold increase in amounts of PRL mRNA. Administration of bromocriptine to 17ß-estradiol-treated animals induced a 15% decrease of PRL mRNA levels compared to those obtained by 17ß-estradiol administered alone. The concomitant administration of 17ß-estradiol and haloperidol resulted in a 50% increase in PRL mRNA levels compared to those measured in animals treated with haloperidol alone. The present results clearly demonstrate that in vivo estrogen as well as dopamine-mediated mechanisms play a regulatory role in PRL mRNA levels in the male rat. 相似文献
7.
The development of a surveillance system to monitor emergency food relief in New York State. 总被引:1,自引:1,他引:0 下载免费PDF全文
A representative sample of emergency food relief (EFR) programs was selected on the basis of a census of 1,488 EFR programs in New York State. The census was a two-stage telephone survey. EFR was provided in every county although there was considerable variation in the amount of EFR per county. The soup kitchen and food pantry components of EFR had to be differentiated. The surveillance system was operational one year after the census began. 相似文献
8.
Differential mortality: some comparisons between England and Wales, Finland and France, based on inequality measures 总被引:4,自引:0,他引:4
Inequalities in mortality between social classes or socioeconomic groups were compared in three European countries, using similar sources of data from large national cohort studies. People registered at a census in 1971 (1975 for France) or a sample of them, were followed until 1980 or 1981. The Gini coefficient, a measure widely used in economics, allowed the comparison of various situations involving different numbers and group sizes. It was applied to age groups 35-44, and 45-54 for men only. According to this measure, inequalities were of the same order in England and Wales and Finland, and greater in France. Differences between the three countries concerning the principal causes of death leading to inequalities were cardiovascular diseases in England and Wales, accidents and cardiovascular diseases in Finland, and cancer and cirrhosis in France. 相似文献
9.
Paul G. Egland Dale A. Pelletier Marilyn Dispensa Jane Gibson Caroline S. Harwood 《Proceedings of the National Academy of Sciences of the United States of America》1997,94(12):6484-6489
A reductive benzoate pathway is the central conduit for the anaerobic biodegradation of aromatic pollutants and lignin monomers. Benzene ring reduction requires a large input of energy and this metabolic capability has, so far, been reported only in bacteria. To determine the molecular basis for this environmentally important process, we cloned and analyzed genes required for the anaerobic degradation of benzoate and related compounds from the phototrophic bacterium, Rhodopseudomonas palustris. A cluster of 24 genes was identified that includes twelve genes likely to be involved in anaerobic benzoate degradation and additional genes that convert the related compounds 4-hydroxybenzoate and cyclohexanecarboxylate to benzoyl-CoA. Genes encoding benzoyl-CoA reductase, a novel enzyme able to overcome the resonance stability of the aromatic ring, were identified by directed mutagenesis. The gene encoding the ring-cleavage enzyme, 2-ketocyclohexanecarboxyl-CoA hydrolase, was identified by assaying the enzymatic activity of the protein expressed in Escherichia coli. Physiological data and DNA sequence analyses indicate that the benzoate pathway consists of unusual enzymes for ring reduction and cleavage interposed among enzymes homologous to those catalyzing fatty acid degradation. The cloned genes should be useful as probes to identify benzoate degradation genes from other metabolically distinct groups of anaerobic bacteria, such as denitrifying bacteria and sulfate-reducing bacteria. 相似文献
10.
Mixed disulfide between lens crystallin and glutathione has been observed in human cataracts and could be formed in vitro by thiol-disulfide exchange reaction. The glutathionyl crystallins have been reported to become partially unfolded. The present paper reports the conformational destabilization by the mixed disulfide formation in calf alpha- and gamma-II crystallin. The conformational stability was studied by the denaturants urea and guanidine hydrochloride (Gdn-HCl), and by proteolytic degradation. The denaturation curves of both urea and Gdn-HCl shift to lower denaturant concentration for crystallins of glutathione mixed disulfide. The decrease in conformational stability is estimated to be 0.22- and 0.92 kcal mol-1 for modified alpha- and gamma-II crystallin, respectively. Proteolytic digestion also shows a faster rate of degradation for the modified crystallins. These results indicate that mixed disulfide destabilizes the crystallin conformation. The destabilization may make crystallins more susceptible to changes as observed in aging lenses. 相似文献