全文获取类型
收费全文 | 2209篇 |
免费 | 211篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 75篇 |
妇产科学 | 114篇 |
基础医学 | 376篇 |
口腔科学 | 124篇 |
临床医学 | 220篇 |
内科学 | 383篇 |
皮肤病学 | 36篇 |
神经病学 | 129篇 |
特种医学 | 185篇 |
外科学 | 227篇 |
综合类 | 46篇 |
一般理论 | 1篇 |
预防医学 | 182篇 |
眼科学 | 80篇 |
药学 | 156篇 |
肿瘤学 | 92篇 |
出版年
2023年 | 21篇 |
2022年 | 22篇 |
2021年 | 43篇 |
2020年 | 20篇 |
2019年 | 27篇 |
2018年 | 35篇 |
2017年 | 24篇 |
2016年 | 21篇 |
2015年 | 28篇 |
2014年 | 36篇 |
2013年 | 83篇 |
2012年 | 75篇 |
2011年 | 81篇 |
2010年 | 67篇 |
2009年 | 48篇 |
2008年 | 80篇 |
2007年 | 99篇 |
2006年 | 103篇 |
2005年 | 104篇 |
2004年 | 111篇 |
2003年 | 64篇 |
2002年 | 76篇 |
2001年 | 79篇 |
2000年 | 74篇 |
1999年 | 73篇 |
1998年 | 33篇 |
1997年 | 28篇 |
1996年 | 37篇 |
1995年 | 27篇 |
1994年 | 27篇 |
1993年 | 29篇 |
1992年 | 43篇 |
1991年 | 66篇 |
1990年 | 51篇 |
1989年 | 65篇 |
1988年 | 56篇 |
1987年 | 50篇 |
1986年 | 50篇 |
1985年 | 44篇 |
1984年 | 25篇 |
1983年 | 25篇 |
1982年 | 22篇 |
1979年 | 17篇 |
1978年 | 23篇 |
1977年 | 15篇 |
1976年 | 20篇 |
1975年 | 16篇 |
1971年 | 21篇 |
1970年 | 16篇 |
1969年 | 17篇 |
排序方式: 共有2442条查询结果,搜索用时 15 毫秒
1.
Scott W. Powers Kelly C. Byars Monica J. Mitchell Susana R. Patton Teresa Schindler Margaret H. Zeller 《Children's Health Care》2003,32(4):297-311
This pilot study examined a behavioral treatment to increase calorie intake in toddlers with cystic fibrosis. Eight toddlers were randomly assigned to behavioral plus nutrition (BEH) or nutrition intervention (NTR) conditions. Calorie intake and weight were measured at pre- and posttreatment. The BEH group showed a trend for changes in calorie intake pre- to posttreatment (p = .07; 40% increase). Results for the BEH and NTR groups did not differ significantly. Most participants achieved weight gains consistent with normal growth. Seventy-five percent had not shown this pattern during the year prior to intervention. These results support the feasibility and potential for behavioral interventions in this age group. 相似文献
2.
K. L. Womer H.-U. Meier-Kriesche P. R. Patton K. Dibadj C. M. Bucci D. Foley S. Fujita B. P. Croker R. J. Howard T. R. Srinivas B. Kaplan 《American journal of transplantation》2006,6(1):209-213
BK virus nephropathy (BKVN) is now recognized as a major cause of renal allograft loss. Recent reports suggest that retransplantation in patients with graft loss due to BKVN is safe after return to dialysis. Since early transplantation is associated with improved outcomes, it would be advantageous if this procedure could be performed prior to ultimate graft loss. However, little data are available regarding the safety of this approach during active viremia. In this report, we describe successful preemptive retransplantation with simultaneous allograft nephrectomy in two patients with active BKVN and viremia at the time of surgery. With 21- and 12-month follow-up, respectively, both patients have stable allograft function and no evidence for active viral replication. We conclude that preemptive retransplantation can be considered in patients with failing allografts due to BKVN. 相似文献
3.
William G. Kohn Jonathan A. Ship Jane C. Atkinson Lauren L. Patton Philip C. Fox 《Journal of oral pathology & medicine》1992,21(2):70-74
Sequential salivary gland scintigraphy with 99mTc-technetium pertechnetate (Tc-99) is a safe, minimally invasive test for study of major salivary glands. However, its relationship to salivary function has not been investigated in detail. We have investigated the relationship between major salivary gland flow rates and Tc-99 scans and developed a new rating scale using scans of a control group with normal salivary function. Salivary flow rates and Tc-99 scans were obtained from healthy, non-medicated subjects (n = 33) and from xerostomic patients (n = 22). There were significant differences between the groups for salivary flow rates and Tc-99 ratings. Significant correlations were found between salivary flow rates and Tc-99 ratings in the control and xerostomic groups. The Tc-99 rating scale proved reliable in assessing salivary dysfunction, and showed a high inter-examiner correlation. These results demonstrate the usefulness of salivary gland scintigraphy in assessing major salivary gland flow rates and the utility of a new rating scale. 相似文献
4.
The recently introduced Technicon H1 analyser uses an improved optical principle to measure the size and haemoglobin concentration of erythrocytes. We have made a serial study of ten patients undergoing phlebotomy to induce mild iron deficiency. The instrument showed the early development of anisohypochromia with subsequent fall in the mean cell haemoglobin concentration (MCHC). Cell volume was preserved until relatively late and during early iron deficient erythropoiesis cell volume would appear to be maintained at the expense of haemoglobin concentration. The Technicon H6000 (conventional technology) used in parallel produced contrasting results indicating anisomicrocytosis with preservation of cell haemoglobin concentration until relatively late. Five cases of severe iron deficiency treated with iron were similarly studied and showed comparable changes on both instruments, with characteristically bimodal cell volume histograms and large increases in red cell distribution width. Our results indicate that the new generation of instruments will generate red cell data of additional clinical value. 相似文献
5.
George K. Morris Arnold Steigerwalt James C. Feeley Edward S. Wong William T. Martin Charlotte M. Patton Don J. Brenner 《Journal of clinical microbiology》1980,12(5):718-721
A new species of Legionella was isolated from soil collected from a creek bank. The name Legionella gormanii sp. nov. is proposed. 相似文献
6.
Direct sequence evaluation of the major outer membrane protein gene variant regions of Chlamydia trachomatis subtypes D'', I'', and L2''. 总被引:3,自引:0,他引:3 下载免费PDF全文
The nucleotide sequences of variable segments (VS) 1, 2, and 4 for the major outer membrane protein gene (omp1) of Chlamydia trachomatis were determined for serologically defined subtypes D', I', and L2'. Asymmetric DNA amplification was used to produce single-stranded DNA for direct sequencing. Amino acid substitutions were detected in VS1, VS2, and VS4 for I', in VS2 for L2', and in VS4 for D'. DNA sequencing of omp1 variant regions may be an important method for evaluating the molecular epidemiology of Chlamydia spp. 相似文献
7.
8.
Campylobacter butzleri sp. nov. isolated from humans and animals with diarrheal illness. 总被引:6,自引:3,他引:6 下载免费PDF全文
J A Kiehlbauch D J Brenner M A Nicholson C N Baker C M Patton A G Steigerwalt I K Wachsmuth 《Journal of clinical microbiology》1991,29(2):376-385
Seventy-eight aerotolerant Campylobacter isolates were characterized phenotypically and by DNA hybridization (hydroxyapatite method at 50 and 65 degrees C). Two DNA relatedness groups were found. (i) Sixty-four strains belonged to aerotolerant Campylobacter DNA hybridization group 2. These organisms were isolated from humans, primarily with diarrheal illness, and animals on several continents. Strains were aerotolerant at 30 and 36 degrees C and catalase negative or weakly catalase positive, grew in media containing glycine and on MacConkey agar, were susceptible to nalidixic acid, and were resistant to cephalothin. The name Campylobacter butzleri sp. nov. is proposed for this group. (ii) DNA hybridization group 1 consisted of the type strain of Campylobacter cryaerophila and 13 additional strains isolated from 10 animals outside the United States and from three humans within the United States. This group was genetically diverse; five strains were closely related to the type strain of C. cryaerophila (DNA hybridization group 1A), and eight strains were more closely related to one another (DNA hybridization group 1B). Strains in DNA hybridization group 1B were phenotypically diverse, with two of eight strains resembling C. cryaerophila. The seven strains from DNA hybridization groups 1A and 1B which resembled C. cryaerophila and the C. cryaerophila type strain were aerotolerant only at 30 degrees C and catalase positive, did not grow in glycine or on MacConkey agar, were generally susceptible to nalidixic acid, and were resistant to cephalothin. The remaining six strains of DNA hybridization group 1B phenotypically resembled C. butzleri; however, they were generally catalase positive and susceptible to nalidixic acid and cephalothin. DNA hybridization group 1B is not designated as a separate species at this time since it cannot, with certainty, be separated genetically from C. cryaerophila or phenotypically from C. butzleri. 相似文献
9.
Analysis of HL and O serotypes of Campylobacter strains by the flagellin gene typing system. 总被引:4,自引:1,他引:4 下载免费PDF全文
We recently developed a molecular typing system for Campylobacter jejuni and Campylobacter coli based on restriction fragment length polymorphism analysis of the flagellin gene,flaA (I.Nachamkin, K. Bohachick, and C.M. Patton, J. Clin. Microbiol. 31:1531-1536, 1993). We extended the typing system to 83 flagellin types (designated flaA-1,flaA-2, etc.) on the basis of analysis of 404 isolates of C. jejuni and C. coli including common serotypes isolated in the United States, a selection of less common serotypes, and serotype reference strains. Of the 295 strains previously shown to belong to common HL and O serotypes (C. M. Patton, M.A. Nicholson, S.M. Ostroff, A.A. Ries, I.K. Wachsmuth, and R.V. Tauxe, J. Clin. Microbiol. 31:1525-1530, 1993), six flaA types accounted for 53.6% of strains as follows: flaA-1, 21.7%; flaA-7, 14.9%; flaA-27, 5.1%; flaA-49, 4.4%; flaA-13, 3.7%; and flaA-21, 3.7%. Seventy-five percent of the strains were within 15 flaA types, 90% were within 30 flaA types, and all 295 strains were contained within 52 flaA types. Within each HL or O serotype, there usually were multiple flaA types. For 12 common HL serotypes and 7 common O serotypes, more than 50% of these isolates were a single flaA type. A database was developed by using commercially available restriction fragment length polymorphism analysis software (ProRFLP; DNA ProScan, Inc., Nashville, Tenn.) that should allow other investigators to perform typing with this system. 相似文献
10.
Comparison of PCR-ELISA and galactomannan detection for the diagnosis of invasive aspergillosis 总被引:1,自引:0,他引:1
AIM: To compare PCR with galactomannan antigen detection for the diagnosis of invasive aspergillosis (IA). METHODS: We prospectively collected serial blood samples from haematological patients at risk of IA, and analysed their samples retrospectively for galactomannan (GM) antigen using the Platelia test and for aspergillus DNA using an in-house PCR-ELISA assay. Matched GM and PCR analyses were performed on 263 samples from 25 patients. Patients were classified for potential IA according to international consensus criteria, with five patients classified as positive (four proven, one probable) and 20 classified as negative (seven possible, 13 no evidence IA). RESULTS: All five patients with IA were positive by PCR with positive results in 24 of 82 samples, whereas three of five patients were positive by GM with four of 82 samples being positive. Three of 20 patients without IA were positive by PCR in 18 of 181 samples, whereas corresponding results for GM detection were one of 20 and one of 181, respectively. Adjustment of ELISA cut-off values and/or the requirement for two consecutive samples to be positive generated different results; however, lowering the positivity index (PI) for GM detection to 0.5 did not improve the sensitivity of the assay. Optimal results for PCR detection and GM were: 100% and 60% sensitivity, 85% and 95% specificity, 0.625 and 0.75 positive predictive value, and 1.0 and 0.8 negative predictive value, with a false-positive sample rate of 8 and 0.4%, positive likelihood ratio of 6.66 and 11.99 and negative likelihood ratio of 0 and 0.42, respectively. CONCLUSIONS: This PCR method is very sensitive for the diagnosis of IA but is associated with a moderate rate of false positives; the GM assay exhibited poor sensitivity but high specificity. Further evaluation of PCR assays for the diagnosis of IA and other invasive fungal infections is warranted. 相似文献