全文获取类型
收费全文 | 22718篇 |
免费 | 1361篇 |
国内免费 | 131篇 |
专业分类
耳鼻咽喉 | 275篇 |
儿科学 | 721篇 |
妇产科学 | 606篇 |
基础医学 | 2242篇 |
口腔科学 | 880篇 |
临床医学 | 1916篇 |
内科学 | 5024篇 |
皮肤病学 | 393篇 |
神经病学 | 1218篇 |
特种医学 | 733篇 |
外国民族医学 | 4篇 |
外科学 | 3935篇 |
综合类 | 857篇 |
现状与发展 | 1篇 |
一般理论 | 21篇 |
预防医学 | 1449篇 |
眼科学 | 570篇 |
药学 | 1885篇 |
中国医学 | 136篇 |
肿瘤学 | 1344篇 |
出版年
2023年 | 295篇 |
2022年 | 874篇 |
2021年 | 1277篇 |
2020年 | 684篇 |
2019年 | 838篇 |
2018年 | 1054篇 |
2017年 | 597篇 |
2016年 | 738篇 |
2015年 | 760篇 |
2014年 | 992篇 |
2013年 | 1265篇 |
2012年 | 1789篇 |
2011年 | 1736篇 |
2010年 | 927篇 |
2009年 | 760篇 |
2008年 | 1192篇 |
2007年 | 1257篇 |
2006年 | 1139篇 |
2005年 | 1050篇 |
2004年 | 997篇 |
2003年 | 802篇 |
2002年 | 798篇 |
2001年 | 206篇 |
2000年 | 177篇 |
1999年 | 161篇 |
1998年 | 150篇 |
1997年 | 102篇 |
1996年 | 85篇 |
1995年 | 90篇 |
1994年 | 78篇 |
1993年 | 51篇 |
1992年 | 107篇 |
1991年 | 86篇 |
1990年 | 98篇 |
1989年 | 91篇 |
1988年 | 66篇 |
1987年 | 71篇 |
1986年 | 59篇 |
1985年 | 61篇 |
1984年 | 51篇 |
1983年 | 58篇 |
1982年 | 33篇 |
1981年 | 32篇 |
1980年 | 36篇 |
1979年 | 47篇 |
1978年 | 30篇 |
1977年 | 35篇 |
1974年 | 44篇 |
1973年 | 38篇 |
1972年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Propofol versus traditional sedative agents for gastrointestinal endoscopy: a meta-analysis. 总被引:6,自引:0,他引:6
Mohammed A Qadeer John J Vargo Farah Khandwala Rocio Lopez Gregory Zuccaro 《Clinical gastroenterology and hepatology》2005,3(11):1049-1056
BACKGROUND & AIMS: Even though propofol has better recovery profile than traditional agents, its use is limited because of the perception of increased complication rates. Because an adequately powered trial comparing risk of propofol with traditional agents is lacking, we performed a meta-analysis of the current literature. METHODS: We searched Medline (1966-October 2004), EMBASE (1980-October 2004), and Cochrane controlled trials registry. The following 4 cardiopulmonary complications were assessed: hypoxia, hypotension, arrhythmias, and apnea. Procedures were divided into 3 groups: esophagogastroduodenoscopy group, colonoscopy group, and endoscopic retrograde cholangiopancreatography/endoscopic ultrasonography group. Pooled odds ratios for complications were calculated for all the procedures combined and then separately for the 3 groups. Random effects models were used for 2-proportion comparisons. RESULTS: Of the 90 citations identified, 12 original studies qualified for this meta-analysis and included 1161 patients. Of these, 634 received propofol, and 527 received midazolam, meperidine, and/or fentanyl. Most of the included studies were randomized trials of moderate quality and nonsignificant heterogeneity (Cochran Q = 4.81, P = .90). Compared with traditional sedative agents, the pooled odds ratio with the use of propofol for developing hypoxia or hypotension for all the procedures combined was 0.74 (95% confidence interval [CI], 0.44-1.24); for EGD, 0.85 (95% CI, 0.33-2.17); for colonoscopy, 0.4 (95% CI, 0.2-0.79); and for ERCP/EUS, 1.07 (95% CI, 0.38-3.01). CONCLUSIONS: Propofol sedation during colonoscopy appears to have lower odds of cardiopulmonary complications compared with traditional agents, but for other procedures, the risk of complications is similar. 相似文献
22.
Arthur J. Matas Raja Kandaswamy Kristen J. Gillingham Lois McHugh Hassan Ibrahim Bertram Kasiske Abhinav Humar 《American journal of transplantation》2005,5(10):2473-2478
Concern persists that prednisone-free maintenance immunosuppression in kidney transplant recipients will be associated with an increase in late allograft dysfunction and graft loss. We herein report 5-year follow-up of a trial of prednisone-free maintenance immunosuppression. From October 1, 1999, through January 31, 2005, at our center, 589 kidney transplant recipients were treated with a protocol incorporating discontinuation of their prednisone on postoperative day 6. At 5 years, actuarial patient survival was 91%; graft survival, 84%; death-censored graft survival, 92%; acute rejection-free graft survival, 84% and chronic rejection-free graft survival, 87%. The mean serum creatinine level (+/-SD) at 1 year was 1.6 +/- 0.6; at 5 years, 1.7 +/- 0.8. In all, 86% of kidney recipients with functioning grafts remain prednisone-free as of April 30, 2005. As compared with historical controls, recipients on prednisone-free maintenance immunosuppression had a significantly lower rate of a number of complications, including cataracts (p < 0.001), posttransplant diabetes mellitus (p < 0.001), avascular necrosis (p = 0.001), and fractures (p = 0.004). We conclude that prednisone-related side effects can be minimized in a protocol incorporating prednisone-free maintenance immunosuppression. Five-year graft outcome remains good. 相似文献
23.
Valsamma Eapen Mona Essa Jakka Mohammed T Abou-Saleh 《Revue canadienne de psychiatrie》2003,48(6):402-407
OBJECTIVE: The prevalence of child psychiatric morbidity in the community is unknown in most developing countries, including those in the Arab region. METHOD: An epidemiologic study was carried out to estimate the prevalence of psychiatric morbidity and to determine the sociodemographic correlates in a sample of children in the community, aged 6 to 18 years, in A1 Ain, United Arab Emirates (UAE). RESULTS: We obtained a prevalence rate of 22.2% for overall morbidity, as classified in the DSM-1V, and 14.3% for those with significant dysfunction, with the most common diagnosis being mood disorders. Female sex, large family size, chronic life difficulties, family history of psychiatric disorder, and alcohol-related problems in a family member were significantly associated with DSM-IV diagnosis. CONCLUSION: Although the prevalence and symptomatology in this Middle East community are similar to those in Western studies, none of these children had received professional help, suggesting serious deficiencies in mental health care services in the country. 相似文献
24.
Mohamed Sabbahi Bruce Etnyre Ibrahim Al-Jawayed Joseph Jankovic 《Clinical neurophysiology》2003,114(2):288-294
OBJECTIVE: The purpose of this study was to examine neurophysiological characteristics of dystonia patients using electromyographic soleus H-reflex methods. METHODS: Thirty normal healthy individuals were compared to 27 patients with focal (cervical) or generalized dystonia. Three H-reflex assessment methods were included: the ratio of maximum H-reflex to direct muscle potential (H/M ratio); vibration inhibition (H(v)/H(c) ratio); and H-reflex recovery curves (HRRC). RESULTS: Average H/M ratios between groups were not statistically significant. The average H(v)/H(c) ratio for the generalized dystonia group was significantly greater than the focal dystonia and normal groups. Average values of the HRRC showed the generalized dystonia group had significantly greater disinhibition than the focal dystonia and control groups during the early inhibition phase. The HRRC for the focal dystonia group was greater than normal and more similar to the generalized dystonia group during the late phases of the recovery curve. The average value of the localized late facilitation phase for the focal dystonia group was significantly greater than the control group and less than the generalized dystonia group. No differences were observed between groups for the average localized late inhibition phase of the recovery curve. CONCLUSIONS: Soleus H-reflex measures identified neurophysiologic differences between generalized dystonia, cervical dystonia and normal conditions. SIGNIFICANCE: This methodology enables analysis of the underlying characteristics of dystonic pathologies using soleus H-reflex methods rather than upper extremity H-reflex techniques. 相似文献
25.
Salim H. Khalil Mohammed H. Qari John M. Jackson Robert Haywood Pyle Hassan El-Solh Abdallah Al-Nasser 《Leukemia research》1994,18(12):881-883
Geographical variations in the incidence of disease are of considerable theoretical and practical importance. It has been claimed that the distribution of acute lymphoblastic leukemia (ALL) phenotypes in Saudi Arabia is different from that recorded in the Western literature. One hundred and twelve (112) patients under 15 years of age, diagnosed as ALL between January 1992 and May 1994 had immunophenotypes performed on their blast cells. Common ALL (cALL) together with pre-B-ALL, formed 86.5% of the total; B-cell 3%, T-cell 6% and null cell 4.5%. These figures are not significantly different from the Western literature. A previous claim from this institution in 1990, that both null and B-cell ALL were significantly increased compared with elsewhere, is not supported by the present figures. Age and sex distribution, and FAB classification, L1 77%, L2 20% and L3 3%, were also of the same order as described elsewhere and, in particular, there was no increase in the frequency of L3 subtype. 相似文献
26.
Amplification and restriction endonuclease digestion of a large fragment of genes coding for rRNA as a rapid method for discrimination of closely related pathogenic bacteria. 总被引:5,自引:4,他引:1 下载免费PDF全文
By use of primers specific to conserved regions of the rRNA gene cluster, a discrete amplicon of approximately 5 kb was amplified by PCR from all 21 bacterial genera investigated. Subsequent endonuclease digestion of the PCR product with HaeIII distinguished between the three species of the human pathogen Francisella spp. on the one hand and four clinically relevant genomic groups of Acinetobacter spp. on the other hand. The described technique has the potential as a rapid method for discriminating between closely related species that are of clinical importance. 相似文献
27.
28.
Johnson KS Chicken DW Pickard DC Lee AC Briggs G Falzon M Bigio IJ Keshtgar MR Bown SG 《Journal of biomedical optics》2004,9(6):1122-1128
The ability to provide the best treatment for breast cancer depends on establishing whether or not the cancer has spread to the lymph nodes under the arm. Conventional assessment requires tissue removal, preparation, and expert microscopic interpretation. In this study, elastic scattering spectroscopy (ESS) is used to interrogate excised nodes with pulsed broadband illumination and collection of the backscattered light. Multiple spectra are taken from 139 excised nodes (53 containing cancer) in 68 patients, and spectral analysis is performed using a combination of principal component analysis and linear discriminant analysis to correlate the spectra with conventional histology. The data are divided into training and test sets. In test sets containing spectra from only normal nodes and nodes with complete replacement by cancer, ESS detects the spectra from cancerous nodes with 84% sensitivity and 91% specificity (per-spectrum analysis). In test sets that included normal nodes and nodes with partial as well as complete replacement by cancer, ESS detects the nodes with cancer with an average sensitivity of 75% and specificity of 89% (per-node analysis). These results are comparable to those from conventional touch imprint cytology and frozen section histology, but do not require an expert pathologist for interpretation. With automation of the technique, results could be made available almost instantaneously. ESS is a promising technique for the rapid, accurate, and straightforward detection of metastases in excised sentinel lymph nodes. 相似文献
29.
Myrna Medlej-Hashim Valérie Delague Eliane Chouery Nabiha Salem Mohammed Rawashdeh Gérard Lefranc Jacques Loiselet André Mégarbané 《BMC medical genetics》2004,5(1):1-6
Background
Hemihyperplasia (hemihypertrophy) is defined as asymmetric body overgrowth of one or more body parts. Hemihyperplasia can be isolated or be part of well-defined syndromes such as in the case of Beckwith-Wiedemann syndrome (BWS). Isolated hemihyperplasia is usually sporadic, but a number of familial occurrences have been described.Case presentation
We describe a Tunisian family in which three maternal cousins and their maternal grandfather present with isolated hemihyperplasia.Conclusions
The etiology of isolated hemihyperplasia is unknown although in BWS, genomic imprinting has been shown to play a role in the asymmetric overgrowth. Given the similarity between these two conditions, it is possible that both may share a common pathogenesis. We also discuss the possible genetic mechanisms leading to the production of hemihyperplasia in this family. 相似文献30.
Mechanisms by which Candida albicans induces endothelial cell prostaglandin synthesis. 总被引:1,自引:5,他引:1 下载免费PDF全文
S G Filler B O Ibe A S Ibrahim M A Ghannoum J U Raj J E Edwards Jr 《Infection and immunity》1994,62(3):1064-1069
One strategy for improving resistance to opportunistic pathogens is to determine host cellular responses during the invasion process and upregulate those responses that are relevant to host defense mechanisms. Within this context, we have shown previously that invasion of endothelial cells by Candida albicans in vitro causes increased production of prostaglandins. As a prerequisite for modulating endothelial cell prostaglandin production, we now characterize the mechanisms through which this process occurs. Endothelial cell invasion by C. albicans appeared to stimulate the conversion of arachidonic acid into prostaglandins by upregulating the synthesis of endothelial cell cyclooxygenase and increasing the activity of the endothelial cell phospholipase. The enhanced activities of these two enzymes were independent of calphostin C-sensitive protein kinase C and resulted in the increased production and extracellular secretion of prostaglandin I2 (PGI2), PGF2 alpha, and PGE2. The secretion of these prostaglandins had no effect on the amount of endothelial cell injury induced by C. albicans. The role of the increased prostaglandin secretion by endothelial cells is likely related to modulation of the leukocyte response at the candida-leukocyte-endothelial cell interface. 相似文献