全文获取类型
收费全文 | 7693篇 |
免费 | 413篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 302篇 |
妇产科学 | 240篇 |
基础医学 | 808篇 |
口腔科学 | 63篇 |
临床医学 | 1131篇 |
内科学 | 1297篇 |
皮肤病学 | 119篇 |
神经病学 | 719篇 |
特种医学 | 172篇 |
外科学 | 802篇 |
综合类 | 74篇 |
一般理论 | 20篇 |
预防医学 | 1085篇 |
眼科学 | 161篇 |
药学 | 412篇 |
中国医学 | 4篇 |
肿瘤学 | 651篇 |
出版年
2024年 | 6篇 |
2023年 | 40篇 |
2022年 | 65篇 |
2021年 | 162篇 |
2020年 | 87篇 |
2019年 | 191篇 |
2018年 | 216篇 |
2017年 | 159篇 |
2016年 | 161篇 |
2015年 | 144篇 |
2014年 | 240篇 |
2013年 | 398篇 |
2012年 | 599篇 |
2011年 | 634篇 |
2010年 | 355篇 |
2009年 | 308篇 |
2008年 | 517篇 |
2007年 | 560篇 |
2006年 | 544篇 |
2005年 | 541篇 |
2004年 | 481篇 |
2003年 | 463篇 |
2002年 | 435篇 |
2001年 | 67篇 |
2000年 | 60篇 |
1999年 | 65篇 |
1998年 | 71篇 |
1997年 | 61篇 |
1996年 | 41篇 |
1995年 | 43篇 |
1994年 | 30篇 |
1993年 | 32篇 |
1992年 | 38篇 |
1991年 | 33篇 |
1990年 | 28篇 |
1989年 | 27篇 |
1988年 | 34篇 |
1987年 | 26篇 |
1986年 | 19篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1979年 | 8篇 |
1977年 | 7篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 9篇 |
1966年 | 5篇 |
排序方式: 共有8114条查询结果,搜索用时 15 毫秒
1.
In the doubly-labelled water (2H2(18)O) method for the measurement of carbon dioxide production rate in man, single exponential disappearance curves for 2H2O and H2(18)O in body water are used; the precision with which the slopes and intercepts of the curves are estimated determines the precision of the estimate of carbon dioxide production rate. In studies with infants, and in computer simulations, the effect of different experimental regimes on the overall precision of the carbon dioxide production estimate was investigated. When the number of data points used was progressively reduced by shortening the total observation period from 7 d (about 3 biological half-lives for the isotopes) to 1 d there was a deleterious effect on precision and in the infants there was an upward bias in the values for carbon dioxide production. When the number of data points was reduced by removing points from the middle of the exponential curves with the maintenance of the 7-d experimental period, precision was also reduced but by less than in the former procedure and there were no consistent trends in the average values for carbon dioxide production. 相似文献
2.
3.
S Lori Brown Roselie A Bright Diane E Dwyer Betsy Foxman 《Journal of human lactation》2005,21(2):169-174
Breast pumps are medical devices used to express milk and maintain the milk supply. The purpose of this study was to characterize adverse events reported to the United States Food and Drug Administration (FDA) on breast pumps. Thirty-seven adverse event reports on breast pumps were identified from the Manufacturer and User Facility Device Experience database between 1992 and 2003. Four additional reports were found in the Device Experience Network database from 1992 to 1996. The most commonly reported adverse events for electric breast pumps were pain, soreness, or discomfort; the need for medical intervention; and breast tissue damage. Most frequently reported problems for manual breast pumps were breast tissue damage and infection. Contamination of breast milk during pumping was also reported. Breast pump adverse events are likely underreported to the FDA. Reporting adverse events is important for improving the design and manufacture of breast pumps and subsequently decreasing adverse events. 相似文献
4.
5.
Sharon Craven Lori Dewar Xianjun Yang Jeff Ginsberg Frederick Ofosu 《Blood coagulation & fibrinolysis》2007,18(3):219-225
Up to 20% of patients develop venographically proven deep-vein thrombosis after elective orthopedic surgery even under the cover of heparin or low molecular weight heparin. The extent to which the chronic inflammation of osteoarthritis requiring elective orthopedic surgery alters in-vivo coagulation and whether any specific alteration influences the development of postoperative thrombosis are unknown. This study compared the concentrations of activated factor VII (FVIIa), tissue factor pathway inhibitor (TFPI), activated factor X (FXa)-TFPI, thrombin-antithrombin, and prothrombin fragment 1+2 (F1+2) in plasmas of 535 healthy individuals (ages 17-76) with those in the preoperative plasmas of 306 arthritis patients (ages 30-92) scheduled for elective knee or hip replacement surgery. C-reactive protein was also measured in the plasmas of approximately 15% of the participants. Age-adjusted concentrations of FVIIa, F1+2, and C-reactive protein were higher in patients than controls, while the concentrations of thrombin-antithrombin, TFPI and FXa-TFPI were similar. Chronic inflammation in the patients was thus associated with increased coagulation in vivo. Without compensatory increases in the concentrations of TFPI (natural inhibitor of prothrombinase), the elevated concentrations of FVIIa in the preoperative plasmas and the trauma associated with surgery may enhance the risk for developing postoperative deep-vein thrombosis. 相似文献
6.
Monica Conciatori Christopher J Stodgell Susan L Hyman Melanie O'Bara Roberto Militerni Carmela Bravaccio Simona Trillo Francesco Montecchi Cindy Schneider Raun Melmed Maurizio Elia Lori Crawford Sarah J Spence Lucianna Muscarella Vito Guarnieri Leonardo D'Agruma Alessandro Quattrone Leopoldo Zelante Daniel Rabinowitz Tiziana Pascucci Stefano Puglisi-Allegra Karl-Ludvig Reichelt Patricia M Rodier Antonio M Persico 《Neuropsychopharmacology》2004,55(4):413-419
BACKGROUND: The HOXA1 gene plays a major role in brainstem and cranial morphogenesis. The G allele of the HOXA1 A218G polymorphism has been previously found associated with autism. METHODS: We performed case-control and family-based association analyses, contrasting 127 autistic patients with 174 ethnically matched controls, and assessing for allelic transmission disequilibrium in 189 complete trios. RESULTS: A, and not G, alleles were associated with autism using both case-control (chi(2) = 8.96 and 5.71, 1 df, p <.005 and <.025 for genotypes and alleles, respectively), and family-based (transmission/disequilibrium test chi(2) = 8.80, 1 df, p <.005) association analyses. The head circumference of 31 patients carrying one or two copies of the G allele displayed significantly larger median values (95.0th vs. 82.5th percentile, p <.05) and dramatically reduced interindividual variability (p <.0001), compared with 166 patients carrying the A/A genotype. CONCLUSIONS: The HOXA1 A218G polymorphism explains approximately 5% of the variance in the head circumference of autistic patients and represents to our knowledge the first known gene variant providing sizable contributions to cranial morphology. The disease specificity of this finding is currently being investigated. Nonreplications in genetic linkage/association studies could partly stem from the dyshomogeneous distribution of an endophenotype morphologically defined by cranial circumference. 相似文献
7.
Ganapathy A Prasad Kenneth K Wang Lori S Lutzke Jason T Lewis Schuyler O Sanderson Navtej S Buttar Louis M Wong Kee Song Lynn S Borkenhagen Lawrence J Burgart 《Clinical gastroenterology and hepatology》2006,4(2):173-178
BACKGROUND & AIMS: The aim of this study was to assess the validity of frozen section analysis of endoscopic mucosal resection (EMR) specimens from Barrett's esophagus as compared with permanent sections for the detection of neoplasia. Frozen sections help to give immediate feedback for surgical procedures. It has not been determined whether EMR can be adequately interpreted by using frozen sections to aid endoscopists in completely resecting neoplastic lesions. METHODS: EMR specimens from Barrett's esophagus with high-grade dysplasia (HGD) and/or carcinoma were tested by frozen section. Pathologists evaluated EMR specimens for the depth of invasion as well as the appearance of clear margins of resection. The kappa statistic was calculated to assess the degree of agreement between the frozen section and permanent section diagnoses. RESULTS: Twenty-three consecutive patients underwent 30 EMRs with frozen section diagnosis. Frozen section revealed a carcinoma in 7 specimens (23%) and dysplasia in 20 (66%). Permanent sections found carcinoma in 8 specimens (26%), dysplasia in 19 specimens (63%), and normal or nondysplastic Barrett's esophagus in the remainder. The kappa statistic for the depth of invasion of EMR specimens was 0.93 (near perfect agreement). The kappa statistic for the margins of the EMR specimens was 0.80 (excellent agreement). CONCLUSIONS: This study indicated that frozen section analysis of esophageal EMR specimens is valid as compared with permanent section. This technique might allow rapid evaluation about the degree and depth of involvement of cancers. This allows physicians to make decisions regarding further therapy if margins are involved or decrease the use of EMR for histologically benign-appearing lesions. 相似文献
8.
9.
Paul J Drinka Peggy Krause Lori Nest Brian M Goodman Stefan Gravenstein 《Infection control and hospital epidemiology》2003,24(11):872-874
Influenza A was cultured in 62 double rooms. The roommate was infected in 12 (19.4%). During 3,294 resident-seasons, influenza was cultured in 208 single rooms (6.3%). Those who lived in double rooms with a culture-positive roommate had a 3.07 relative risk (CI95, 1.61-5.78) of acquiring influenza. 相似文献
10.