全文获取类型
收费全文 | 1168篇 |
免费 | 142篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 96篇 |
妇产科学 | 17篇 |
基础医学 | 116篇 |
口腔科学 | 44篇 |
临床医学 | 108篇 |
内科学 | 331篇 |
皮肤病学 | 29篇 |
神经病学 | 21篇 |
特种医学 | 189篇 |
外科学 | 78篇 |
综合类 | 98篇 |
预防医学 | 74篇 |
眼科学 | 9篇 |
药学 | 78篇 |
中国医学 | 3篇 |
肿瘤学 | 60篇 |
出版年
2024年 | 3篇 |
2023年 | 16篇 |
2022年 | 13篇 |
2021年 | 25篇 |
2020年 | 21篇 |
2019年 | 8篇 |
2018年 | 21篇 |
2017年 | 41篇 |
2016年 | 38篇 |
2015年 | 30篇 |
2014年 | 64篇 |
2013年 | 69篇 |
2012年 | 25篇 |
2011年 | 23篇 |
2010年 | 63篇 |
2009年 | 69篇 |
2008年 | 28篇 |
2007年 | 68篇 |
2006年 | 35篇 |
2005年 | 29篇 |
2004年 | 27篇 |
2003年 | 20篇 |
2002年 | 9篇 |
2001年 | 32篇 |
2000年 | 13篇 |
1999年 | 16篇 |
1998年 | 77篇 |
1997年 | 65篇 |
1996年 | 60篇 |
1995年 | 50篇 |
1994年 | 46篇 |
1993年 | 42篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 17篇 |
1989年 | 24篇 |
1988年 | 24篇 |
1987年 | 13篇 |
1986年 | 20篇 |
1985年 | 17篇 |
1984年 | 10篇 |
1983年 | 13篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 12篇 |
1975年 | 9篇 |
排序方式: 共有1360条查询结果,搜索用时 15 毫秒
1.
We have evaluated the in vitro effects of bromocriptine (Br), on the hepatic cytochrome P-450 monooxygenase system of rats pretreated with saline phenobarbitone (PB) and beta-naphthoflavone (BNF). Br inhibited ethoxyresorufin O-dealkylase (EROD) activity in liver microsomes of rats pretreated with saline and PB but not in BNF pretreated animals. Maximum inhibition of EROD activity by Br in the microsomes of saline and PB pretreated rats were 50%-60% of the control. In contrast, a dual effect was observed on aminopyrine N-demethylase activity (APD) by Br in microsomes of saline, PB and BNF pretreated rats. At a low concentration (25 microM), Br inhibited the activity of APD to a similar extent in all pretreatment groups; however, with higher concentrations of Br (50 microM to 300 microM), enhancement of APD activity was observed. Br (300 microM) increased the APD activity to 2-3 times the control level in microsomes of rats pretreated with saline, PB or BNF. Spectral studies revealed a Type II binding of Br to cytochrome P-450 from microsomes of saline and PB pretreated rats. A reverse type I binding was observed for BNF induced microsomes. In addition, Br also enhanced NADPH cytochrome c (P-450) reductase activity to a similar extent in all pretreatment groups. These results suggest that the inhibition of EROD activity may be due to direct binding by Br to certain isozymes of cytochrome P-450 and that the enhancing effect of Br on APD activity may be in part due to the activation of the NADPH cytochrome c reductase component of the cytochrome P-450 monooxygenase system. 相似文献
2.
Calciphylaxis – a topical overview 总被引:3,自引:0,他引:3
G Arseculeratne† AT Evans‡ SM Morley† 《Journal of the European Academy of Dermatology and Venereology》2006,20(5):493-502
'Calciphylaxis', a calcification syndrome associated with ischaemic cutaneous necrosis, is acquired naturally in humans in disease states. It is a life and limb-threatening complication, usually observed in patients with renal disease and secondary hyperparathyroidism, but known to occur in the absence of renal or parathyroid disease. The reported mortality rate, which ranges from 60-80%, relates to wound infection, sepsis and organ failure. It is a small-vessel vasculopathy, which is estimated to occur in about 4% of haemodialysis patients. Clinically, violaceous, reticulate areas of cutaneous necrosis and eschar may be evident, particularly in the extremities. In addition to the clinical picture, a raised calcium phosphorous product, an elevated parathyroid hormone level, radiographic evidence of vessel and soft-tissue calcification and the finding of mural calcification affecting small arteries and arterioles on histopathology help to confirm the diagnosis of this entity which generally has a poor prognosis. A high index of suspicion and an active multidisciplinary management approach, with rigorous attention to wound care and prevention of sepsis, are vital in the management of these patients. In this overview, we discuss the pathophysiology, clinical features and associations, risk factors, diagnosis and management issues relating to calciphylaxis. 相似文献
3.
Bastiaan R Klarenbeek Alexander AFA Veenhof Elly SM de Lange Willem A Bemelman Roberto Bergamaschi Piet Heres Antonio M Lacy Wim T van den Broek Donald L van der Peet Miguel A Cuesta 《BMC surgery》2007,7(1):16
Backround
Diverticulosis is a common disease in the western society with an incidence of 33–66%. 10–25% of these patients will develop diverticulitis. In order to prevent a high-risk acute operation it is advised to perform elective sigmoid resection after two episodes of diverticulitis in the elderly patient or after one episode in the younger (< 50 years) patient. Open sigmoid resection is still the gold standard, but laparoscopic colon resections seem to have certain advantages over open procedures. On the other hand, a double blind investigation has never been performed. The Sigma-trial is designed to evaluate the presumed advantages of laparoscopic over open sigmoid resections in patients with symptomatic diverticulitis. 相似文献4.
5.
6.
A novel analogue of human alpha-interferon (IFN-alpha CON1) was tested for its ability to modify the hepatic cytochrome P-450-dependent mixed-function oxidase system in the hamster. This cloned interferon was derived by selecting the most frequently observed amino acid sequences at each position in the known human alpha-interferon subtypes. IFN-alpha CON1 had a biphasic effect on cytochrome P-450 and related drug biotransformation in the hamster causing an initial increase followed by a significant depression. IFN-alpha CON1 also had a biphasic effect on cytochrome P-450 in the lung, adrenal and spleen but only a depressant effect in the kidney. This effect was not due to morphological damage and followed the species specificity for this type of interferon. Both the increase and the decrease in cytochrome P-450 could be prevented by the administration of the protein synthesis inhibitor puromycin. Various isozymes of cytochrome P-450 induced by phenobarbital, beta-napthaflavone and clofibrate were also depressed by this interferon. The results presented in this report suggest that IFN-alpha CON1 interferon will likely depress drug biotransformation in humans because the antiviral effects and the "anti-cytochrome P-450" effect of interferons cannot be separated, and this interferon has antiviral properties in both hamster and human cells. Clinically relevant drug interactions may be common during the concomitant use of this interferon and other drugs that are metabolized by cytochrome P-450. 相似文献
7.
8.
9.
Isolation of a new clathrin heavy chain gene with muscle-specific expression from the region commonly deleted in velo-cardio-facial syndrome 总被引:3,自引:4,他引:3
Sirotkin H; Morrow B; DasGupta R; Goldberg R; Patanjali SR; Shi G; Cannizzaro L; Shprintzen R; Weissman SM; Kucherlapati R 《Human molecular genetics》1996,5(5):617-624
Velo-cardio-facial syndrome (VCFS) and DiGeorge syndrome (DGS) are
developmental disorders characterized by a spectrum of phenotypes including
velopharyngeal insufficiency, conotruncal heart defects and facial
dysmorphology among others. Eighty to eighty-five percent of VCFS/DGS
patients are hemizygous for a portion of chromosome 22. It is likely that
the genes encoded by this region play a role in the etiology of the
phenotypes associated with the disorders. Using a cDNA selection protocol,
we isolated a novel clathrin heavy chain cDNA (CLTD) from the VCFS/DGS
minimally deleted interval. The cDNA encodes a protein of 1638 amino acids.
CLTD shares significant homology, but is not identical to the ubiquitously
expressed clathrin heavy chain gene. The CLTD gene also shows a unique
pattern of expression, having its maximal level of expression in skeletal
muscle. Velopharyngeal insufficiency and muscle weakness are common
features of VCFS patients. Based on the location and expression pattern of
CLTD, we suggest hemizygosity at this locus may play a role in the etiology
of one of the VCFS-associated phenotypes.
相似文献
10.
Mahadevan MM; McIntosh Q; Miller MM; Breckinridge SM; Maris M; Moutos DM 《Human reproduction (Oxford, England)》1998,13(4):979-982
Cryopreservation of human zygotes and embryos has been routinely performed
by in-vitro fertilization clinics for many years. Karran and Legge (1996)
first reported that formaldehyde (FA) present in the cryoprotective
solutions can have a deleterious effect on mouse oocytes. FA is a
cytotoxic, carcinogenic and mutagenic chemical. The effect of FA on mouse
zygotes was investigated. In addition, the concentrations of FA in
propanediol (PROH) obtained from various sources were determined. Pooled
1-cell embryos were dispensed into droplets of modified Ham's F10 or human
tubal fluid containing various concentrations of FA. Since bovine serum
albumin (BSA) may minimize toxicity additional trials were done as above in
the absence of BSA. FA concentration in the standard 1.5 M PROH, from
different sources in water, was measured in the same assay using a standard
curve of 0-100 microM FA. FA in a complex medium had a significant
deleterious effect on embryo development and hatching but only at 1 mM
concentration (P < 0.000001; see Tables I-III). There was no significant
effect of FA at 100 microM. However, in a simple medium even 50 microM FA
decreased embryo hatching. FA was present in 1.5 M PROH from different
sources (range 1.0-35.3 microM concentration). It appears that FA
concentrations do not increase with storage because FA concentrations were
low even after opening and storage for 3 years on the shelf. This suggests
that FA is a contaminant during the manufacturing process and may vary from
manufacturer to manufacturer and batch to batch. Until further studies are
done to confirm the lack of toxicity to embryos during cryopreservation
(with or without FA scavengers) it may be prudent to screen all batches of
cryoprotectants for FA as part of quality control.
相似文献