全文获取类型
收费全文 | 629篇 |
免费 | 42篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 34篇 |
妇产科学 | 4篇 |
基础医学 | 63篇 |
口腔科学 | 35篇 |
临床医学 | 50篇 |
内科学 | 147篇 |
皮肤病学 | 23篇 |
神经病学 | 11篇 |
特种医学 | 100篇 |
外科学 | 73篇 |
综合类 | 25篇 |
预防医学 | 33篇 |
眼科学 | 6篇 |
药学 | 51篇 |
中国医学 | 1篇 |
肿瘤学 | 19篇 |
出版年
2021年 | 21篇 |
2020年 | 4篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 18篇 |
2015年 | 14篇 |
2014年 | 20篇 |
2013年 | 39篇 |
2012年 | 32篇 |
2011年 | 16篇 |
2010年 | 31篇 |
2009年 | 27篇 |
2008年 | 17篇 |
2007年 | 16篇 |
2006年 | 23篇 |
2005年 | 12篇 |
2004年 | 8篇 |
2003年 | 13篇 |
2002年 | 12篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 19篇 |
1998年 | 35篇 |
1997年 | 25篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1994年 | 23篇 |
1993年 | 23篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 15篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有678条查询结果,搜索用时 15 毫秒
51.
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52.
Avani Shah Keyuri Jariwala Snehalata Gupte Preeti Sharma Kanchan Mishra Kanjaksha Ghosh 《Transfusion and apheresis science》2018,57(5):672-675
Background
Extended phenotyping is one of the important method of reducing red cell alloimmunisation. Extended phenotyping of red cells from voluntary donors have many uses in addition to its application in population genetics. As there was very little data extended phenotyping on a cohort of Indian Voluntary blood donors this project was undertaken.Study design & methodology
200 regular voluntary blood donors having ‘O’ blood group were included for red cell antigen typing of Rh (D,C,E,c,e), Kell (K, k, Kpa, Kpb), Duffy (Fya, Fyb), Kidd (Jka, Jkb), Lewis(Lea, Leb), P(P1), MNS (M, N,S,s), and Lutheran (Lua, Lub), Colton (Coa, Cob), Diago (Diaa, Wra), Vw and Xga antigens using conventional antisera provided by DIAGAST. Calculations of antigen and phenotypes frequencies were expressed as percentages.Results
Out of 200 ‘O’ group blood donors, 96.5% were Rh D and 2.5% were K positive. Amongst Rh antigens, e was the most common (100%) followed by D, C (91.0%), c (50.5%) and E (16.5%) with DCe/DCe (R1R1, 48.0%) being the most common phenotype. In Kell blood group system, we found k antigen to be 100% and a rare phenotype Kp (a?+?b+) was found in 1% of the donors. For Kidd and Duffy blood group systems, Jk (a?+?b+) and Fy (a?+?b-) were the most common phenotypes (39.0% and 64.0%, respectively). In the MNS blood group system, M?+?N+ (67.5%) and S?+?s+(43.5%) were the most common phenotypes. There were antigens like Cw(3.5%), K(2.3%), Kpa(1.2%), Ina(1.0%), Vw(1.2%), Coa(4.5%), Cob(1%), Lua(1.75%), Dia+(1.2%), and Wra+(0.6%) with frequency < 5% in the donor population.Conclusion
Extensively antigen phenotypes group ‘O’ red cells showed significant variation with other population from India as well as with Caucasian and black population. Extensive phenotyping ‘O’ group regular blood donors of red cell antigens is very useful to prepare in-house red cell panels for identification of alloantibodies. 相似文献53.
Hyperbaric oxygen therapy improves angiogenesis and bone formation in critical sized diaphyseal defects 下载免费PDF全文
JP Grassmann J Schneppendahl AR Hakimi M Herten M Betsch TT Lögters S Thelen M Sager M Wild J Windolf P Jungbluth M Hakimi 《Journal of orthopaedic research》2015,33(4):513-520
Besides the use of autologous bone grafting several osteoconductive and osteoinductive methods have been reported to improve bone healing. However, persistent non‐union occurs in a considerable number of cases and compromised angiogenesis is suspected to impede bone regeneration. Hyperbaric oxygen therapy (HBO) improves angiogenesis. This study evaluates the effects of HBO on bone defects treated with autologous bone grafting in a bone defect model in rabbits. Twenty‐four New‐Zealand White Rabbits were subjected to a unilateral critical sized diaphyseal radius bone defect and treated with autologous cancellous bone transplantation. The study groups were exposed to an additional HBO treatment regimen. Bone regeneration was evaluated radiologically and histologically at 3 and 6 weeks, angiogenesis was assessed by immunohistochemistry at three and six weeks. The additional administration of HBO resulted in a significantly increased new bone formation and angiogenesis compared to the sole treatment with autologous bone grafting. These results were apparent after three and six weeks of treatment. The addition of HBO therapy to autologous bone grafts leads to significantly improved bone regeneration. The increase in angiogenesis observed could play a crucial role for the results observed. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:513–520, 2015. 相似文献
54.
55.
Complementary medicine: use and attitudes among GPs 总被引:9,自引:0,他引:9
BACKGROUND: Information about use and attitudes of GPs towards
complementary medicine is required in order to inform the debate about its
place within mainstream medicine. There is evidence that public use of
complementary medicine is particularly high in the South-West of England.
OBJECTIVE: This study aimed to determine the use of, and attitudes towards,
complementary medicine among GPs. METHODS: A questionnaire survey was
performed of all primary care physicians working in the health service in
Devon and Cornwall. RESULTS: Replies were received from 461 GPs, a response
rate of 47%. A total of 314 GPs (68%, range 32-85%) had been involved in
complementary medicine in some way during the previous week. One or other
form of complementary medicine was practised by 74 of the respondents
(16%), the two most common being homoeopathy (5.9%) and acupuncture (4.3%).
In addition, 115 of the respondents (25%) had referred at least one patient
to a complementary therapist in the previous week, and 253 (55%) had
endorsed or recommended treatment with complementary medicine.
Chiropractic, acupuncture and osteopathy were rated as the three most
effective therapies, and the majority of respondents believed that these
three therapies should be funded by the health service. A total of 176
(38%) of respondents reported adverse effects, most commonly after
manipulation. CONCLUSION: Over two-thirds of the GPs in Devon and Cornwall
who responded to the survey had been involved with complementary medicine
in some way during the previous week. This figure is higher than the
national average. The majority of respondents believed that acupuncture,
chiropractic and osteopathy were effective and should be funded by the NHS.
相似文献
56.
57.
Expression of phosphorylcholine-specific B cells during murine development 总被引:1,自引:0,他引:1 下载免费PDF全文
NH Sigal AR Pickard ES Metcalf PJ Gearhart NR Klinman 《The Journal of experimental medicine》1977,146(4):933-948
The TEPC 15 (T15) clonotype, a putatively germline antibody specificity, does not appear in the neonatal B-cell repertoire until approximately 1 wk of age. This report extends this observation by the demonstration that (a) the T15 clonotype follows similar kinetics of appearance in germfree as well as conventionally-reared mice; (b) maternal influences and genetic background play a minor role in the development of the T15 clonotype since CBFI neonates raised by C57BL/6 or BALB/c mothers acquire the T15 clonotype at the same time in ontogeny as BALB/c neonates; (c) the lack of phosphorylcholine (PC)-specific B cells shortly after birth is reflected in a dearth of PC-binding cells in the neonate as well; and (d) no PC-specifc B cells are found in 19-day fetal liver or in bone marrow until 7 days of life, coincident with their appearance in the spleen. These findings, along with a previous report that PC-specific splenic B cells are tolerizable as late as day 10 after birth, confirm the invariant, late occurrence of the T15 clonotype and support a highly- ordered, rigorously predetermined mechanism for the acquisition of the B- cell repertoire. The results are discussed in light of other studies on the ontogeny of B-cell specificity, and in terms of the implications on the mechanism by which antibody diversity is generated. 相似文献
58.
We investigated the ability of blood B cells, bone marrow (BM) plasma cells, and terminal leukemic plasma cells (T-PCL) from patients with multiple myeloma (MM) to migrate on extracellular matrix proteins. Hyaluronan (HA), but not collagen type I, collagen type IV, or laminin, promoted migration of MM blood B cells, as determined by time-lapse video microscopy. Between 13% and 20% of MM blood B cells migrated on HA with an average velocity of 19 micron/min, and greater than 75% of MM blood B cells exhibited vigorous cell movement and plasma membrane deformation, as did circulating T-PCL and extraskeletal plasma cells from patients with MM. In contrast, plasma cells obtained from BM of patients with MM lacked motility on all substrates tested and did not exhibit cell membrane protrusions or cellular deformation. MM blood B cells and MM plasma cells from all sources examined expressed the HA- binding receptors receptor for HA-mediated motility (RHAMM) and CD44. On circulating MM B cells, both RHAMM and CD44 participated in HA- binding, indicating their expression ex vivo in an activated conformation. In contrast, for the majority of BM plasma cells in the majority of patients with MM, expression of RHAMM or CD44 was not accompanied by HA binding. A minority of patients did have HA-binding BM plasma cells, involving both RHAMM and CD44, as evidenced by partial blocking with monoclonal antibodies (MoAbs) to RHAMM or to CD44. Despite HA binding by both RHAMM and CD44, migration of MM blood B cells on HA was inhibited by anti-RHAMM but not by anti-CD44 MoAbs, indicating that RHAMM but not CD44 mediates motility on HA. Thus, circulating B and plasma cells in MM exhibit RHAMM- and HA-dependent motile behavior indicative of migratory potential, while BM plasma cells are sessile. We speculate that a subset(s) of circulating B or plasma cells mediates malignant spread in myeloma. 相似文献
59.
An unusual case of infective endocarditis involving a right coronary artery to superior vena cava fistula 下载免费PDF全文
Ujjval Jariwala MD Rani K. Hasan MD MHS Eric M. Thorn MD Sammy Zakaria MD MPH 《Catheterization and cardiovascular interventions》2015,85(4):620-624
Coronary artery fistulas (CAFs) are rare and mostly congenital anomalous connections between a coronary artery and a cardiac chamber or great vessel. Most CAFs are small, asymptomatic, and found incidentally during cardiac imaging. However, they can lead to serious complications including myocardial infarction, congestive heart failure, arrhythmias, or fistula rupture. CAFs have been associated with infective endocarditis, but to our knowledge, this complication has never been reported involving an isolated CAF to an otherwise anatomically normal great vessel. We report the first case of this complication in a 49‐year‐old man with a presumed streptococcus vegetation found within an isolated large, tortuous CAF connecting the right coronary artery to the superior vena cava. After completing antibiotic treatment, transcatheter closure of the CAF was performed. Since then, the patient has remained symptom‐free. This case demonstrates that CAF closure is feasible following CAF‐associated endocarditis, and that closure may represent a viable strategy for reducing risk of recurrent infection. © 2014 Wiley Periodicals, Inc. 相似文献
60.
M Tavassoli S Javadi R Firozi F Rezaei AR Khezri M Hadian 《Iranian Journal of Parasitology》2012,7(4):110-115