全文获取类型
收费全文 | 55420篇 |
免费 | 5739篇 |
国内免费 | 80篇 |
专业分类
耳鼻咽喉 | 744篇 |
儿科学 | 1519篇 |
妇产科学 | 1428篇 |
基础医学 | 8427篇 |
口腔科学 | 1392篇 |
临床医学 | 7485篇 |
内科学 | 10149篇 |
皮肤病学 | 672篇 |
神经病学 | 4568篇 |
特种医学 | 1795篇 |
外国民族医学 | 1篇 |
外科学 | 7095篇 |
综合类 | 1066篇 |
一般理论 | 36篇 |
预防医学 | 5932篇 |
眼科学 | 982篇 |
药学 | 4391篇 |
中国医学 | 71篇 |
肿瘤学 | 3486篇 |
出版年
2022年 | 354篇 |
2021年 | 720篇 |
2020年 | 498篇 |
2019年 | 861篇 |
2018年 | 953篇 |
2017年 | 712篇 |
2016年 | 887篇 |
2015年 | 953篇 |
2014年 | 1273篇 |
2013年 | 2018篇 |
2012年 | 2734篇 |
2011年 | 2910篇 |
2010年 | 1586篇 |
2009年 | 1451篇 |
2008年 | 2534篇 |
2007年 | 2677篇 |
2006年 | 2662篇 |
2005年 | 2613篇 |
2004年 | 2456篇 |
2003年 | 2370篇 |
2002年 | 2431篇 |
2001年 | 1708篇 |
2000年 | 1700篇 |
1999年 | 1506篇 |
1998年 | 741篇 |
1997年 | 638篇 |
1996年 | 516篇 |
1995年 | 558篇 |
1994年 | 509篇 |
1993年 | 488篇 |
1992年 | 1204篇 |
1991年 | 1159篇 |
1990年 | 1116篇 |
1989年 | 1040篇 |
1988年 | 945篇 |
1987年 | 966篇 |
1986年 | 930篇 |
1985年 | 957篇 |
1984年 | 771篇 |
1983年 | 679篇 |
1982年 | 505篇 |
1981年 | 427篇 |
1980年 | 428篇 |
1979年 | 632篇 |
1978年 | 480篇 |
1977年 | 406篇 |
1976年 | 413篇 |
1974年 | 420篇 |
1973年 | 362篇 |
1972年 | 374篇 |
排序方式: 共有10000条查询结果,搜索用时 40 毫秒
991.
The concentration of ethanol in blood, breath or urine constitutes important evidence for prosecuting drunk drivers. For various reasons, the reliability of the results of forensic alcohol analysis are often challenged by the defence. One such argument for acquittal concerns the notion that alcohol could be produced naturally in the body, hence the term 'auto-brewery' syndrome. Although yeasts such as Candida albicans readily produce ethanol in-vitro, whether this happens to any measurable extent in healthy ambulatory subjects is an open question. Over the years, many determinations of endogenous ethanol have been made, and in a few rare instances (Japanese subjects with very serious yeast infections) an abnormally high ethanol concentration (> 80 mg/dl) has been reported. In these atypical individuals, endogenous ethanol appeared to have been produced after they had eaten carbohydrate-rich foods. A particular genetic polymorphism resulting in reduced activity of enzymes involved in hepatic metabolism of ethanol and a negligible first-pass metabolism might explain ethnic differences in rates of endogenous ethanol production and clearance. Other reports of finding abnormally high concentrations of ethanol in body fluids from ostensibly healthy subjects suffer from deficiencies in study design and lack suitable control experiments or used non-specific analytical methods. With reliable gas chromatographic methods of analysis, the concentrations of endogenous ethanol in peripheral venous blood of healthy individuals, as well as those suffering from various metabolic disorders (diabetes, hepatitis, cirrhosis) ranged from 0-0.08 mg/dl. These concentrations are far too low to have any forensic or medical significance. The notion that a motorist's state of intoxication was caused by endogenously produced ethanol lacks merit. 相似文献
992.
993.
Bror Jonzon Ingvar Bjarnason Chris Hawkey John Jones Andrew Goddard Urban Fagerholm Pär Karlsson 《Inflammopharmacology》2003,11(4-6):437-444
COX-inhibiting nitric oxide donators (CINODs) are a new class of drugs in development for the treatment of acute and chronic pain. They comprise a COX-inhibiting moiety linked to a nitric-oxide-donating component and are designed to provide an innovative mechanism of action of balanced COX inhibition and controlled nitric oxide donation. Through these pathways, CINODs should provide analgesic and anti-inflammatory efficacy, while offering gastrointestinal safety through the tissue-protective effects of nitric oxide donation. AZD3582 [4-(nitrooxy)butyl-(2S)-2-(6-methoxy-2-naphthyl)propanoate] is the first agent in the CINOD class to enter extensive clinical development. Pre-clinical studies demonstrate that AZD3582 has a superior gastrointestinal safety profile to naproxen, while demonstrating analgesic and anti-inflammatory efficacy. In healthy human volunteers, AZD3582 caused little gastrointestinal damage compared with equimolar doses of naproxen. Studies to evaluate the longer-term gastrointestinal safety of AZD3582, alongside its efficacy in alleviating chronic and acute pain, are ongoing. 相似文献
994.
995.
996.
997.
Allen L Seligson Brian K Campion Jason W Brown Ron C Terry Renata Kucerova Martina Bienova Marian Hajduch Milos Sovak 《Drug development research》2003,59(3):292-306
Nonsteroidal antiandrogens (AA) cannot be topically used for androgenetic alopecia (AGA) because of systemic resorption. A new class of androgen receptor (AR) suppressors designed for safe topical treatment of AGA was synthesized from (3‐amino‐2‐hydroxy‐2‐methyl‐N‐(4‐nitro‐3‐trifluoromethyl)phenyl) propanamide (BP‐34), to contain perfluoroalkyl moieties. The trifluoromethyl derivative (fluridil) at 10 μM decreased expression of the AR in LNCaP human cells by 95%, its serum half‐life was 6 h; it decomposes hydrolytically to BP‐34 and trifluoroacetic acid. Acute intraperitoneal maximum tolerated dose (MTD) of fluridil in mice is 270–300 mg/kg/d and the subacute MTD is 450 mg/kg/d. The oral LD50 in mice was 2,872 mg/kg in males, 2,232 mg/kg in females, and >2,500 mg/kg in rats. Fluridil solution in isopropanol was not cutaneously absorbed in rabbits, did not sensitize or show any phototoxic or photoallergic effects on guinea pig skin, and demonstrated no skin irritation potential in rabbits and humans. Fluridil solid induced only slight and reversible eye irritancy in rabbits and displayed no cytotoxicity to rabbit corneal fibroblasts in vitro. Fluridil demonstrated no significant mutagenicity potential by Ames method. In a double‐blind study, 43 males with AGA, Norwood grade II to Va, used topical 2% fluridil in isopropanol or the vehicle daily for 12 months. Anagens (growing hairs) increased in the fluridil group from 76% to 89%. All hematological and biochemistry values remained within normal range, including testosterone, which varied but seasonally. No fluridil or its decomposition product (BP‐34) was detected in serum. No adverse side effects were reported. Drug Dev. Res. 59:292–306, 2003. © 2003 Wiley‐Liss, Inc. 相似文献
998.
The pH and bicarbonate concentrations of luminal fluids in the efferent ducts of the rat were estimated from pH measurements of samples in vitro under conditions of controlled temperature and carbon dioxide tension. The pH of scrotal blood was estimated to be more acidic than systemic blood (mean pH=7.44) at either of the putative scrotal carbon dioxide tensions (5% and 7%, pH, respectively,=7.42 and 7.28). For PCO2 tensions of 5% and 7%, respectively, the data indicated that the pH in the efferent ducts was significantly higher (distal initial zone pH=7.55 or 7.41; coni vasculosi pH=7.66 or 7.51; p < 0.01) than in fluid entering (rete testis fluid, pH=7.34 or 7.20) or leaving the ducts (zone 1a of the epididymal duct 7.26 or 7.11). Bicarbonate concentrations were also significantly higher (p < 0.01) in the efferent ducts (35.4 +/- 4.7 mM, distal initial zone; 45.2 +/- 7.6 mM, coni vasculosi) than in fluids entering (22.9 +/- 3.6 mM) or leaving (20.4 +/- 4.9 mM) the ducts. Estimates of the reabsorption of bicarbonate and fluid indicated that 96% of the testicular output of bicarbonate was reabsorbed in the efferent ducts, but there was also some secretion of bicarbonate into the ducts. It is concluded that luminal pH and bicarbonate levels in the efferent ducts of the rat are high relative to those found in the epididymis where low pH and bicarbonate contributes to sperm quiescence during storage. Nevertheless, the high rate of bicarbonate reabsorption in the efferent ducts is a major contributor to the establishment of the low pH and bicarbonate milieu of the epididymis. 相似文献
999.
Jones DK Dardis R Ervine M Horsfield MA Jeffree M Simmons A Jarosz J Strong AJ 《Neurosurgery》2000,47(2):306-13; discussion 313-4
OBJECTIVE: Issues surrounding the nature of the edema associated with traumatic brain injury in humans, and its evolution in the acute phase, remain unresolved. This study aimed to characterize the topographical nature of the pathophysiological changes in human traumatic brain injury with diffusion tensor magnetic resonance imaging. METHODS: Multislice diffusion-weighted magnetic resonance imaging data were acquired from five patients undergoing elective ventilation for management of traumatic focal contusion or hematomas. The diffusion tensor and the T2-weighted intensity were then computed for every voxel in the image data set for each patient. The topographical distribution of abnormalities in the trace of the diffusion tensor and T2-weighted images were characterized by cluster analysis. RESULTS: In four patients with technically satisfactory data, a narrow band of tissue was observed in the periphery of focal lesions, which was characterized by selective reduction in the trace of the diffusion tensor, without any associated increase in the T2-weighted signal intensity. CONCLUSION: This change is interpreted as indicating either a partial redistribution of water from the extra- to intracellular compartment, or a reduction in the diffusivity of water in the intracellular or cytosolic environment. These diffusion and T2-weighted characteristics are also found in early ischemic change, hence, such regions may represent potentially salvageable tissue at risk of permanent damage. The study illustrates the advantage of using information contained within the diffusion tensor in addition to more conventional imaging sequences. 相似文献
1000.
Hardwick RH Taylor A Thompson MH Jones E Roe AM 《Annals of the Royal College of Surgeons of England》2000,82(1):24-26
Abscesses after appendicitis occur in some patients despite timely surgery and antibiotics. The Streptococcus milleri group of bacteria are commonly associated with gastrointestinal abscesses. This study investigated the relationship between S. milleri and abscess formation after appendicectomy a total of 301 patients (172 males, 129 females, median age 22 years) with appendicitis were identified retrospectively from the hospital PAS computer system who had an appendicectomy and peritoneal bacteriology swabs taken. All but one patient had prophylactic antibiotics. Patients were divided into three groups according to peritoneal bacteriology: group 1 (S. milleri +/- mixed faecal organisms, n = 61); group 2 (mixed faecal organisms, n = 126); and group 3 (sterile, n = 114). The chi squared and Student t-tests were used for statistical analysis. Thirteen (21%) of group 1 patients developed an intra-abdominal abscess compared with 4 (3%) in group 2 and 2 (1.7%) in group 3 (P < 0.0001). There was no difference in the prevalence of gangrenous or perforated appendicitis between groups 1 and 2 (56% versus 52%) but these worse forms of appendicitis were less common in group 3 (22%). Group 1 patients had a mean total hospital stay of 10 days versus 6 days for group 2 and 4 days for group 3 (P < 0.001). S. milleri was associated with a 7-fold increase in abscess formation after appendicectomy and a longer hospital stay. Antibiotic prophylaxis did not prevent this complication. 相似文献