全文获取类型
收费全文 | 691篇 |
免费 | 53篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 51篇 |
妇产科学 | 6篇 |
基础医学 | 60篇 |
口腔科学 | 33篇 |
临床医学 | 59篇 |
内科学 | 146篇 |
皮肤病学 | 17篇 |
神经病学 | 16篇 |
特种医学 | 100篇 |
外科学 | 91篇 |
综合类 | 32篇 |
预防医学 | 59篇 |
眼科学 | 4篇 |
药学 | 54篇 |
中国医学 | 1篇 |
肿瘤学 | 20篇 |
出版年
2021年 | 15篇 |
2020年 | 4篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 11篇 |
2015年 | 16篇 |
2014年 | 17篇 |
2013年 | 34篇 |
2012年 | 31篇 |
2011年 | 17篇 |
2010年 | 31篇 |
2009年 | 30篇 |
2008年 | 23篇 |
2007年 | 23篇 |
2006年 | 31篇 |
2005年 | 19篇 |
2004年 | 18篇 |
2003年 | 15篇 |
2002年 | 13篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 21篇 |
1998年 | 36篇 |
1997年 | 25篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1994年 | 24篇 |
1993年 | 23篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 16篇 |
1988年 | 17篇 |
1987年 | 11篇 |
1986年 | 16篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1969年 | 2篇 |
1967年 | 4篇 |
1948年 | 2篇 |
排序方式: 共有751条查询结果,搜索用时 531 毫秒
111.
胃肠胰胰岛淀粉样多肽的定位和表达 总被引:5,自引:3,他引:2
胰岛淀粉样多肽(islet armyloid polypeptide,IAPP)是1986年瑞典学者Westermarket al[1,2 ]从胰岛素瘤患者的瘤组织,糖尿病猫及Ⅱ型糖尿病患者胰岛淀粉样沉积物中分离出来的一种多肽,几乎在同时,英国生物化学家Cooper et al[3,4]也从Ⅱ型糖尿病患者的胰岛淀粉样沉积物中分离出该肽.IAPP又称为amylin.对IAPP的分子结构、基因表达和生理作用等已有许多报道[5].近年来,在IAPP定位、表达及胃肠胰IAPP免疫反应(immunoreactive,IR)细胞定位、发生、发育方面的研究报道,为探讨IAPP的生理作用及疾病状态下的改变,提供了形态学依据,现综述如下. 相似文献
112.
113.
Evolution of transmitted HIV‐1 drug resistance and viral subtypes circulation in Italy from 2006 to 2016 下载免费PDF全文
114.
通常认为异体血液采集的献血者发生不良反应和损伤的发生率低,但自体献血者不良反应发生率的数据则自相矛盾,单采不良反应的发生率和预测献血者反应的因素还知之甚少。 本文分析了作者输血中心1998年1月到2001年6月记录的血液和单采献血者的所有不良反应。作者对发生不良反应与未报告任何不良反应的献血者之间的人口统计学和身体特征进行比较,以便确定不良反应预测因素的存在。 相似文献
115.
LINKED ARTICLES
This is a rebuttal by the authors (Green et al., pp. 1523–1536 of this issue) to a commentary by Parrott, pp. 1518–1520 of this issue. To view the article by Green et al. visit http://dx.doi.org/10.1111/j.1476-5381.2011.01819.x. To view the commentary by Parrott visit http://dx.doi.org/10.1111/j.1476-5381.2012.01941.xWe thank Prof Parrott (Parrott 2012) for his interest in our review (Green et al., 2012). Our main aim was to discuss the problems that arise in interpreting data obtained when administering 3,4-methylenedioxymethamphetamine (MDMA) to experimental animals in terms of possible clinical consequences and vice versa, not to disparage the evidence that Ecstasy is neurotoxic in humans. We presented evidence that the pharmacokinetics of MDMA in rats and primates are fundamentally different from the pharmacokinetics of the drug in humans. Because the plasma half-life of the drug in rats is 10 times shorter than in humans, the acute adverse events in rats may be minimal compared with those in humans, and this includes body temperature and endocrine changes. Conversely, the rapid metabolism of the drug in rats to form neurotoxic metabolites may result in more severe long-term effects in that species than those that may occur in humans.We had no intention of suggesting that there was no evidence for some recreational Ecstasy users presenting with evidence of 5-HT neurotoxicity, albeit it is clear from the literature that some of this evidence remains open to several interpretations. What we did claim was that pure 3,4-methylenedioxymethamphetamine (MDMA) taken alone was unlikely to cause 5-HT neurotoxicity in man. Here we must emphasize the term MDMA, as it is crucial to our discussion. Parrott, in contrast, uses the term ‘Ecstasy/MDMA’ several times when discussing neurotoxicity (Parrott, 2012). This association of Ecstasy with MDMA is one of the major problems of translation that we addressed. The Ecstasy tablet that most recreational users buy and ingest is not necessarily MDMA. Indeed, in many cases, it clearly is not. The tablet is often adulterated with other compounds, and one investigation identified no less than 14 substances other than MDMA in Ecstasy tablets, which users nevertheless presumably believed contained only MDMA (Vogels et al., 2009). Many of the adulterants identified were also psychoactive and included compounds structurally related to MDMA such as 3,4-methylenedioxyethylamphetamine and 2-methylamino-1-(3,4-methylenedioxyphenyl)butane, which have poorly researched pharmacology and toxicology. In addition, most recreational users of Ecstasy also knowingly ingest other psychoactive compounds such as alcohol and cannabis. Alcohol, for example, alters the pharmacokinetics of MDMA (Hamida et al., 2009). While, as Parrott states, clinical studies have attempted to allow for these confounding factors in any examination of the physical and psychological effects of MDMA in humans, such analysis is always limited not only by the other compounds the evaluators are unaware of, but also drugs perhaps not even considered to be relevant by the user and therefore not disclosed. It is unlikely that coffee and ‘energy drinks’ such as Red Bull are always disclosed, but there is now good preclinical evidence that caffeine, which incidentally has also been found as an adulterant in Ecstasy tablets, enhances both the hyperthermia and neurotoxicity induced in rats by MDMA (Camarasa et al., 2006; Vanattou-Saïfoudine et al., 2010). And this brings us to the crux of the problem and weakness of all the clinical data cited by Parrott (2012). A basic tenet of all good clinical pharmacology is accurate knowledge of the doses administered, frequency of administration and any confounding factors such as other drugs being consumed. None of these data are available with any precision in the clinical studies quoted. Of course one has some indication as to dose (although as Vogels et al., (2009) reported, the dose contained in illicitly obtained tablets is highly variable) and frequency of drug ingestion, but this information is generally obtained from the user whose recall is likely to be limited or who decides to obfuscate. Crucially, the information can never take into account the problem of drug tablet adulteration. The fact that hair or urine samples detect MDMA merely shows the user has consumed the drug, not how much or when or what other drugs were taken concurrently.We never suggested that MDMA exposure was not going to be associated with physical or psychological change. However such changes are not necessarily associated with long-term neurotoxic damage. We have shown that long-term behavioural effects can occur in rats both with and without 5-HT neurotoxicity (Fone et al., 2002; Bull et al., 2003; Rodsiri et al., 2011). It is interesting that Parrott approvingly quotes the Verheyden et al. (2003) study in support of his contention that neurotoxic damage has occurred. Because this study noted that the majority of persons reporting chronic psychiatric problems reported ‘improved mental health’ after quitting the drug, this surely allows us to conclude that the drug had produced subacute changes rather than any that could be associated with long-term neurotoxic damage.A further limitation to any clinical study is that one cannot perform prospective studies with the aim of investigating whether long-term neurotoxic events occur, so weaknesses arise with regard to any psychological abnormalities observed. Are persons with high risk of psychiatric problems more likely to misuse the drug, or does the drug induce changes in high-risk individuals? If high risk also happened to be associated with 5-HT abnormalities in the brains, then any conclusion that MDMA has induced neurotoxicity is spurious.We most certainly did not suggest that MDMA acted as a neurotoxin only under conditions of severe hyperthermia as is stated by Parrot in his sixth paragraph (Parrott, 2012). We have been involved in many studies on the effects of MDMA on body temperature in rats (see Docherty and Green, 2010) including one that demonstrated that neurotoxicity can occur in the absence of hyperthermia (O''Shea et al., 1998) and another that showed that hyperthermia worsens neurotoxic damage (Green et al., 2004). In our review, what we did propose was that because of the very different pharmacokinetics of MDMA in rats and humans, it is probable that humans would suffer serious or fatal adverse events at plasma levels below those likely to be required to induce 5-HT neurotoxicity.We emphasize again that we are not denying the clinical observations reviewed by Parrott, but conclude that the effects seen cannot be ascribed solely to the effects of MDMA, as he seems to be proposing. We also repeat our contention that MDMA in combination with other drugs may induce neurotoxicity and this could be said to be supported by the clinical studies quoted by Parrott.Finally, we can but assume that Parrott concurs with our principal conclusion that ‘the doses currently being used to investigate the possible therapeutic benefits of MDMA are unlikely to produce any severe acute or importantly any long-term neurotoxic damage in the human brain’ as he used such a dose (100 mg or approximately 1.4 mg·kg −1) in one of his recent studies in human volunteers (Parrott et al., 2011). 相似文献116.
J Saki AR Meamar H Oormazdi L Akhlaghi S Maraghi M Mohebali S Khademvatan E Razmjou 《Iranian Journal of Parasitology》2010,5(1):25-34
Background
Leishmaniasis is a protozoan disease cause by Leishmania genus. Anthroponotic and zoonotic cutaneous leishmaniasis are endemic in Iran. The aim of this study was to identify the causative agent of cutaneous leishmaniasis by mini-exon gene in five regions of Khuzestan Province, southwest of Iran.Methods
From 2007 to 2008 in this cross-sectional study, cutaneous samples were collected from patients referred to Health Centers and Hospitals of the Khuzestan Province for cutaneous leishmaniasis diagnosis and cultured in Novy-MacNeal-Nicolle (NNN) and RPMI 1640. The propagated promastigotes were harvested and Leishmania species of cutaneous leishmaniasis were identified by RFLP and DNA sequencing of the PCR generated fragments.Results
L. major and L. tropica were the causative agents of cutaneous leishmaniasis by predominantly of L. major species. The alignment of the mini-exon sequencing isolates with reported sequencing of L. major and L. tropica revealed 92%-99% identity.Conclusion
Our study showed that mini-exon PCR-RFLP was useful method to identify the causative species of cutaneous leishmaniasis. 相似文献117.
118.
Background
Linguatula serrata, one of the parasitic zoonoses, inhabits the canine respiratory system (final hosts). The objective of this study was to determine the prevalence rate of L. serrata nymphs in mesenteric lymph nodes (MLNs) of cattle and buffaloes (intermediate hosts) that were processed in the Ahvaz, Iran abattoir.Methods
During November 2010 to March 2011, 223 animals (119 cattle and 104 buffaloes), in different sex and three age groups (<2, 2–< 3 and 3-> 3 years old) were sampled randomly at Ahvaz abattoir. Up to 35 grams of their mesenteric lymph nodes were examined separately for nymphal stages of L. serrata by digesting the samples with acid- pepsin method, collected the nymphs and counted under stereomicroscope.Results
Overall 37(16.6%) of 223 animals were infected with L. serrata nymphs in their mesenteric lymph nodes. Prevalence of the infection in cattle and buffaloes were 16.8% and 16.3% respectively. The number of collected nymphs of MLNs was ranged from 1 to 16. No significant differences were seen in the infection rates between males and females (sexes) and age groups in the cattle and buffaloes (P <0.05).Conclusion
Linguatula serrata has an active life cycle in the studied area and a zoonotic potential for transmission between animal and human. Avoiding use of raw MLNs to dogs can help reduce the infection. 相似文献119.
The objective of the present study was to describe the relationship between some reproductive parameters, hormonal levels, and some biochemical properties of blood serum in rams under the Afyon province conditions. The total protein and globulin were positively (P?<?0.01) correlated with sperm motility and sperm concentration in all of rams. Total lipid was negatively (P?<?0.05) correlated with sperm motility and concentration in Daglic, and it was positively (P?<?0.01) correlated with percentage of abnormal spermatozoa in Chios rams. Total lipid and cholesterol was positively (P?<?0.01) correlated with triiodothyronine in all of rams and was negatively (P?<?0.05) correlated with testosterone in Daglic rams. Percentage of abnormal spermatozoa were negatively (P?<?0.01) correlated with alanine amino transaminase (ALT) level, but were positively (P?<?0.01) associated with aspartate amino transaminase (AST) level and AST/ALT ratio in all of rams. 相似文献
120.