全文获取类型
收费全文 | 1836篇 |
免费 | 89篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 133篇 |
妇产科学 | 49篇 |
基础医学 | 274篇 |
口腔科学 | 50篇 |
临床医学 | 144篇 |
内科学 | 321篇 |
皮肤病学 | 51篇 |
神经病学 | 98篇 |
特种医学 | 141篇 |
外科学 | 133篇 |
综合类 | 111篇 |
一般理论 | 2篇 |
预防医学 | 129篇 |
眼科学 | 106篇 |
药学 | 108篇 |
中国医学 | 1篇 |
肿瘤学 | 91篇 |
出版年
2023年 | 8篇 |
2022年 | 24篇 |
2021年 | 34篇 |
2020年 | 27篇 |
2019年 | 27篇 |
2018年 | 49篇 |
2017年 | 35篇 |
2016年 | 47篇 |
2015年 | 32篇 |
2014年 | 58篇 |
2013年 | 92篇 |
2012年 | 120篇 |
2011年 | 134篇 |
2010年 | 74篇 |
2009年 | 73篇 |
2008年 | 118篇 |
2007年 | 164篇 |
2006年 | 111篇 |
2005年 | 107篇 |
2004年 | 92篇 |
2003年 | 72篇 |
2002年 | 62篇 |
2001年 | 26篇 |
2000年 | 20篇 |
1999年 | 23篇 |
1998年 | 45篇 |
1997年 | 27篇 |
1996年 | 30篇 |
1995年 | 26篇 |
1994年 | 20篇 |
1993年 | 22篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 18篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 8篇 |
1973年 | 2篇 |
排序方式: 共有1958条查询结果,搜索用时 15 毫秒
1.
Jamaal L. Benjamin MD PhD Rebecca Dennis DO Stacy White Jr MD David Munson MD Sudha A. Anupindi MD Maciej Piskunowicz MD Kassa Darge MD PhD Ami Gokli MD Misun Hwang MD 《Journal of ultrasound in medicine》2020,39(5):1031-1036
Bowel diseases of prematurity, including necrotizing enterocolitis, are dreaded ailments of neonates. Early diagnosis is difficult, with clinical and radiographic findings often inconclusive. We present a novel use of contrast-enhanced ultrasound in detection of pediatric bowel disease. Early identification of compromised blood flow or an at-risk bowel can be quantitatively detected and monitored. This ability has implications for guidance of emerging therapies, allowing targeting of inflammation. These findings represent an advancement in detection of bowel disease in neonates. 相似文献
2.
目的由于卒中风险随着狭窄严重程度的增加而升高,因此认为颈内动脉(ICA)接近闭塞患者的卒中风险很高。在现有的随机试验中,还没有专门针对这种情况进行探讨,因此其处理尚存在争汶。方法:对相关文献进行系统评价。结果:对ICA接近闭塞患者的处理还存在争议:一些学者支持进行干预,而另一些学者则认为存在风险或没有益处而反对进行干预。在ICA接近闭塞的有症状患者中进行一项比较外科治疗与最佳内科治疗的多中心前瞻性随机试验似乎非常困难,因为这类研究需要大量的患者。尽管如此,基于目前的证据,似乎很难拒绝手术治疗。结论:由于目前对ICA接近闭塞患者的最佳处理方案仍存在着争议,因此需要前瞻性观察性研究以证实其在有症状和无症状人群中的患病率以及相关的卒中风险。基于目前的证据,大多数医疗中心选择手术治疗,但它相对干内科治疗的特粱尚右待证章. 相似文献
3.
4.
5.
Rupture of the distal biceps tendon: evaluation with MR imaging 总被引:2,自引:0,他引:2
6.
PURPOSE: To describe a patient diagnosed with pheochromocytoma in the third trimester of pregnancy and discuss the perioperative and anesthetic management. CLINICAL FEATURES: A 32-yr-old previously healthy woman (gravida 4, para 2) presented to our tertiary care obstetrical hospital at 34 weeks five days gestation with a history of labile blood pressure and severe hypertension. A week prior to admission she began having episodes of severe headache, dizziness, sweating and nausea. On a routine obstetric visit she was noted to be severely hypertensive with a blood pressure of 200/120 mmHg. Biochemical investigations confirmed the diagnosis of pheochromocytoma and magnetic resonance imaging demonstrated a 3 cm x 3 cm right adrenal mass. The patient was invasively monitored in the intensive care unit and treated with alpha- followed by beta-blockade with phenoxybenzamine and metoprolol. A multidisciplinary conference was organized involving endocrinology, anesthesiology, general surgery and obstetrics to determine the most appropriate management of the patient. An uncomplicated laparoscopic adrenalectomy was performed following a period of recovery after an uneventful elective Cesarean delivery. CONCLUSIONS: The primary goals in the management of pheochromocytoma in pregnancy are early diagnosis, avoidance of a hypertensive crisis during delivery and definitive surgical treatment. Timing of surgical resection will depend on the gestational age at which diagnosis is made. Cesarean section is the preferred mode of delivery when the tumour is still present. This case illustrates that with antenatal diagnosis, advanced methods of tumour localization, adequate preoperative adrenergic blockade and team planning, pheochromocytoma in pregnancy can be treated successfully. 相似文献
7.
8.
High HIV prevalence and risk behaviors in men who have sex with men in Chennai, India 总被引:4,自引:0,他引:4
Go VF Srikrishnan AK Sivaram S Murugavel GK Galai N Johnson SC Sripaipan T Solomon S Celentano DD 《Journal of acquired immune deficiency syndromes (1999)》2004,35(3):314-319
OBJECTIVE: To estimate HIV and sexually transmitted disease (STD) prevalence and behavioral risk characteristics of men who have sex with men (MSM) in Chennai, India. METHODS: A cross-sectional population-based random sample survey was conducted in 2001. Randomly selected residents of 30 slums in Chennai were interviewed for behavioral risk factors through face-to-face interviews. Sera and urine were examined for syphilis, HIV-1, gonorrhea, and chlamydia. Logistic regression analyses were used to assess associations between MSM status and HIV infection and to identify risk characteristics of MSM. RESULTS: Of 774 men, 46 reported (5.9%) sex with other men. MSM were more likely to be seropositive for HIV (odds ratio [OR] = 8.57; 95% confidence interval [CI]: 1.83, 40.23) and were more likely to have a history of STD (OR = 2.66; 95% CI: 1.18, 6.02) than non-MSM. Men who used illicit drugs in past 3 months (adjusted odds ratio [AOR] = 4.01; 95% CI: 1.92, 8.41), ever exchanged money for sex (AOR = 3.93; 95% CI: 1.97, 7.84), or were ever tested for HIV (AOR = 3.72; 95% CI: 1.34, 10.34) were significantly more likely to report sex with men. CONCLUSIONS: MSM in Chennai slums are at high risk for HIV. HIV prevention strategies aimed at changing unsafe drug and sexual practices should target the general population of men, with specific attention to areas with high rates of MSM. 相似文献
9.
Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability 总被引:1,自引:15,他引:1
La Spada AR; Peterson KR; Meadows SA; McClain ME; Jeng G; Chmelar RS; Haugen HA; Chen K; Singer MJ; Moore D; Trask BJ; Fischbeck KH; Clegg CH; McKnight GS 《Human molecular genetics》1998,7(6):959-967
X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG
repeat expansion in the first exon of the androgen receptor (AR) gene.
Disease-associated alleles (37-66 CAGs) change in length when transmitted
from parents to offspring, with a significantly greater tendency to shift
size when inherited paternally. As transgenic mice carrying human AR cDNAs
with 45 and 66 CAG repeats do not display repeat instability, we attempted
to model trinucleotide repeat instability by generating transgenic mice
with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions
in their genomic context. Studies of independent lines of AR YAC transgenic
mice with CAG 45 alleles reveal intergenerational instability at an overall
rate of approximately 10%. We also find that the 45 CAG repeat tracts are
significantly more unstable with maternal transmission and as the
transmitting mother ages. Of all the CAG/CTG repeat transgenic mice
produced to date the AR YAC CAG 45 mice are unstable with the smallest
trinucleotide repeat mutations, suggesting that the length threshold for
repeat instability in the mouse may be lowered by including the appropriate
flanking human DNA sequences. By sequence-tagged site content analysis and
long range mapping we determined that one unstable transgenic line has
integrated an approximately 70 kb segment of the AR locus due to
fragmentation of the AR YAC. Identification of the cis - acting elements
that permit CAG tract instability and the trans -acting factors that
modulate repeat instability in the AR YAC CAG 45 mice may provide insights
into the molecular basis of trinucleotide repeat instability in humans.
相似文献
10.
Roles of specific amino acids in the N terminus of Pseudomonas aeruginosa flagellin and of flagellin glycosylation in the innate immune response 下载免费PDF全文
The Toll-like receptor 5 (TLR5) binding site has been predicted to be in the N terminus of the flagellin molecule. In order to better define the interaction between the N-terminal amino acids of Pseudomonas aeruginosa flagellin and TLR5, site-specific mutations were generated between residues 88 and 97 of P. aeruginosa PAK flagellin as well as outside of this region. The mutant flagellins were expressed in Escherichia coli BL21(plysS), purified by affinity chromatography, and passed through a polymyxin B column to remove contaminating lipopolysaccharide (LPS). Their ability to stimulate interleukin-8 (IL-8) release from A549 cells was examined. The cloned mutated genes were used to complement a PAK fliC mutant in order to test for effects on motility and on IL-8 release by purified flagellar preparations. All the mutations, single or double, in the predicted TLR5 binding region reduced IL-8 signaling to less than 95% of the wild-type flagellin levels, but the single mutation outside the binding region had no effect. Changes made at two amino acid sites resulted in loss/reduction of motility; however, changes made at single sites, i.e., Q83A, L88A, R90A, M91A, L94A, and Q97A, had no effect on motility. The mutated genes encoding two of the motile but poorly signaling flagellins had no compensatory mutations to allow motility. Thus, while it is speculated that pathogen-associated molecular patterns (PAMPs) have evolved in locations that are essential to maintain function, it appears that there is tolerance for at least single amino acid changes in the PAMP of P. aeruginosa flagellin. The purpose of flagellin glycosylation in P. aeruginosa is unknown. In order to examine its role, if any, in signaling an inflammatory response, we used whole flagella from the motile chromosomal mutant strains PAKrfbC and PAO1rfbC, which are defective in flagellin glycosylation. IL-8 release from A549 cells stimulated with nonglycosylated flagellar preparations (having less then 1 picogram of LPS/mug) was significantly reduced compared to their respective wild-type flagellar preparations, indicating a role of flagellar glycosylation in the proinflammatory action of Pseudomonas flagellin. The basis of the latter activity is unknown, since the glycosylation sites are found in the D3 domain of flagellins and the TLR5 binding site is located in the D1 domain. Thus, P. aeruginosa flagellin has evolved additional flagellar signaling mechanisms over that described for Salmonella flagellin. 相似文献