全文获取类型
收费全文 | 8934篇 |
免费 | 717篇 |
国内免费 | 60篇 |
专业分类
耳鼻咽喉 | 64篇 |
儿科学 | 313篇 |
妇产科学 | 304篇 |
基础医学 | 1159篇 |
口腔科学 | 278篇 |
临床医学 | 845篇 |
内科学 | 1836篇 |
皮肤病学 | 72篇 |
神经病学 | 538篇 |
特种医学 | 345篇 |
外科学 | 1485篇 |
综合类 | 206篇 |
一般理论 | 10篇 |
预防医学 | 427篇 |
眼科学 | 348篇 |
药学 | 480篇 |
1篇 | |
中国医学 | 31篇 |
肿瘤学 | 969篇 |
出版年
2024年 | 9篇 |
2023年 | 59篇 |
2022年 | 75篇 |
2021年 | 215篇 |
2020年 | 148篇 |
2019年 | 195篇 |
2018年 | 254篇 |
2017年 | 135篇 |
2016年 | 191篇 |
2015年 | 245篇 |
2014年 | 335篇 |
2013年 | 355篇 |
2012年 | 548篇 |
2011年 | 627篇 |
2010年 | 391篇 |
2009年 | 364篇 |
2008年 | 552篇 |
2007年 | 597篇 |
2006年 | 570篇 |
2005年 | 516篇 |
2004年 | 461篇 |
2003年 | 410篇 |
2002年 | 314篇 |
2001年 | 303篇 |
2000年 | 262篇 |
1999年 | 209篇 |
1998年 | 80篇 |
1997年 | 85篇 |
1996年 | 69篇 |
1995年 | 49篇 |
1994年 | 59篇 |
1993年 | 52篇 |
1992年 | 112篇 |
1991年 | 101篇 |
1990年 | 100篇 |
1989年 | 103篇 |
1988年 | 68篇 |
1987年 | 73篇 |
1986年 | 62篇 |
1985年 | 55篇 |
1984年 | 41篇 |
1983年 | 39篇 |
1982年 | 27篇 |
1981年 | 32篇 |
1980年 | 25篇 |
1979年 | 23篇 |
1978年 | 19篇 |
1977年 | 25篇 |
1976年 | 17篇 |
1975年 | 13篇 |
排序方式: 共有9711条查询结果,搜索用时 15 毫秒
41.
Norepinephrine was infused intravenously for 30 minutes into chronically catheterized sheep fetuses averaging 133 days' gestation. At infusion rates of 3.9, 12, and 39 micrograms/min, heart rate initially decreased as much as 40 bpm and then gradually increased to 50 bpm above the control value by the end of the infusion. Thereafter, heart rate increased further, and by the end of a 30-minute recovery period, heart rate was still 66 bpm above the control value. In fetuses pretreated with either a ganglionic blocker or a parasympathetic blocker, norepinephrine caused a large and sustained rise in heart rate by 124 bpm, which declined rapidly when the infusion was terminated. These results suggest that circulating norepinephrine affects fetal heart rate by several mechanisms: a baroreceptor-mediated suppression, a direct stimulation by norepinephrine, a gradual weakening of the vagal and an increase in cardiac sensitivity to sympathetic stimulation. In addition, there appears to be a long-term positive correlation between fetal heart rate and circulating norepinephrine levels. 相似文献
42.
43.
Girardet RG McClain N Lahoti S Cheung K Hartwell B McNeese M 《The Pediatric infectious disease journal》2001,20(2):144-147
BACKGROUND: The urine-based ligase chain reaction (LCR) assay for Chlamydia trachomatis and Neisseria gonorrhoeae is an attractive alternative to culture because of the relative ease with which specimens may be collected, transported and processed. In addition LCR offers superior sensitivity while maintaining high specificity when compared with culture in various studies of adolescents and adults. A study comparing LCR to culture has not been published concerning children. METHODS: We conducted a prospective, comparison trial of the urine-based LCR test for Chlamydia trachomatis and Neisseria gonorrhoeae as compared with culture among children at a specialized referral center for evaluation for alleged sexual assault. Of the 1,010 children presenting to the center during the study period, 164 met the study requirements for risk of a sexually transmissible disease and collection of both culture and urine LCR specimens. RESULTS: Eight specimens tested positive by both methods for C. trachomatis. Another 10 specimens tested positive for C. trachomatis by LCR but were negative by culture. No patient with a negative LCR for C. trachomatis had a positive culture. For N. gonorrhoeae 2 specimens tested positive by both methods, and 3 specimens tested positive by LCR but negative by culture. No patient with a negative LCR for N. gonorrhoeae had a positive culture. CONCLUSIONS: The low prevalence of disease in the study population precluded statistical analysis. LCR may prove to be as specific and more sensitive than culture for the detection of C. trachomatis and N. gonorrhoeae in children. Further studies are needed. 相似文献
44.
Tatad AM Nesin M Peoples J Cheung S Lin H Sison C Perlman J Cunningham-Rundles S 《Neonatology》2008,94(1):8-15
BACKGROUND: Neonatal susceptibility to bacterial infection is associated with an immature immune system, but the role of different bacterial antigens in specific responses is largely unknown. OBJECTIVE: To evaluate differences in intracellular cytokine response to physiologically relevant bacterial antigens in term and preterm infants as compared with adults. METHODS: Cord blood samples from preterm and term neonates and adult peripheral blood samples were cultured ex vivo with and without whole heat-killed bacteria. Intracellular leukocyte production of interleukin (IL)-6, IL-10, IL-12, and IL-8 responses was assessed by flow cytometry. RESULTS: Monocytes were the primary producers of all mediators. Escherichia coli was the most potent stimulant. Lactobacillus plantarum 299v activated fewer monocytes as compared with E. coli for all responses (p < 0.05), except for IL-12 in term neonates. IL-6 response to Staphylococcus epidermidis was lower in both groups of neonates as compared with adults (p = 0.023 and p = 0.001). IL-8 response to S. epidermidis was lower in term as compared with preterm neonates and adults (p = 0.003). IL-10 response to group B streptococci was lower in term neonates as compared with adults and higher in preterm as compared with term neonates (p = 0.015). CONCLUSIONS: Monocytes from term neonates compared to preterm neonates show a downregulated anti-inflammatory response to specific bacteria. High neonatal response to pathogenic E. coli in the preterm infant could cause uncontrolled inflammatory response, while lower IL-6 response to S. epidermidis in neonates may indicate a basis for vulnerability to S. epidermidis infection. 相似文献
45.
46.
Immunomodulatory and anti-SARS activities of Houttuynia cordata 总被引:1,自引:0,他引:1
Lau KM Lee KM Koon CM Cheung CS Lau CP Ho HM Lee MY Au SW Cheng CH Lau CB Tsui SK Wan DC Waye MM Wong KB Wong CK Lam CW Leung PC Fung KP 《Journal of ethnopharmacology》2008,118(1):79-85
BACKGROUND: Severe acute respiratory syndrome (SARS) is a life-threatening form of pneumonia caused by SARS coronavirus (SARS-CoV). From late 2002 to mid 2003, it infected more than 8000 people worldwide, of which a majority of cases were found in China. Owing to the absence of definitive therapeutic Western medicines, Houttuynia cordata Thunb. (Saururaceae)(HC) was shortlisted by Chinese scientists to tackle SARS problem as it is conventionally used to treat pneumonia. AIM OF THE STUDY: The present study aimed to explore the SARS-preventing mechanisms of HC in the immunological and anti-viral aspects. RESULTS: Results showed that HC water extract could stimulate the proliferation of mouse splenic lymphocytes significantly and dose-dependently. By flow cytometry, it was revealed that HC increased the proportion of CD4(+) and CD8(+) T cells. Moreover, it caused a significant increase in the secretion of IL-2 and IL-10 by mouse splenic lymphocytes. In the anti-viral aspect, HC exhibited significant inhibitory effects on SARS-CoV 3C-like protease (3CL(pro)) and RNA-dependent RNA polymerase (RdRp). On the other hand, oral acute toxicity test demonstrated that HC was non-toxic to laboratory animals following oral administration at 16 g/kg. CONCLUSION: The results of this study provided scientific data to support the efficient and safe use of HC to combat SARS. 相似文献
47.
BACKGROUND: Embedded fetal bone after surgical termination of midtrimester pregnancy is a recognized complication. Most cases occur in the uterine cavity; however, this case demonstrates that a cervicovaginal fistula can be caused by embedment of bone in the cervical canal. CASE: A 19-year-old girl presented with persistent smelly vaginal discharge 4 years after surgical pregnancy termination. On examination she had a cervicovaginal fistula with embedded fetal bone that was subsequently removed surgically. CONCLUSION: Cervicovaginal fistula can be a complication of surgical termination of midtrimester pregnancy as fetal bones can become embedded in the cervical canal during removal. 相似文献
48.
Falls are common among the elderly population. Examinations for the cause of falls are usually mundane, but may be challenging, leading to surprising diagnoses. We report on a previously healthy elderly man who presented with repeated falls and rapidly progressive limitations in mobility, in addition to a stutter. Neuroimaging was particularly helpful for making the diagnosis in this patient. 相似文献
49.
Kevin Martell Hans Chung Gerard Morton Danny Vesprini Chia-Lin Tseng Ewa Szumacher Patrick Cheung Will Chu Stanley Liu Andrew Loblaw 《Canadian Urological Association journal》2022,16(8):E437
IntroductionWe aimed to determine the minimum cross-sectional ellipsoid area on magnetic resonance (MR) of intraprostatic nodules that best predicts for subsequent targeted biopsies revealing ≥ grade group (GG) 2 disease.MethodsForty-six patients previously diagnosed with GG 1 prostate adenocarcinoma who received cognitively fused, MR-guided, transperineal targeted biopsies in addition to six random biopsies were included in this analysis. A Youden cutpoint analysis was used to determine the ellipsoid area in the axial plane best predicting for ≥GG 2 disease within the targeted biopsy cores and logistic regression used to assess the result.ResultsMedian time from MR imaging to targeted biopsy was 2.4 (1.4–5.5) months. Forty of 46 (87%) patients had one nodule and 6/46 (13%) had two separate nodules on MR that received targeted biopsy. Of the 52 nodules, five (10%), 33 (63%), and 14 (27%) were Prostate Imaging-Reporting and Data System (PI-RADS) 3, 4, and 5, respectively. Thirteen (25%), six (12%), and 33 (64%) were in the anterior, medial, and posterior regions of the prostate, respectively. Median area was 0.72 (0.49–1.29) cm2 (average diameter 9.5 mm). Fifteen of 46 (33%) patients had ≥1 random biopsy and 20/52 (38%) nodules had ≥1 targeted biopsy revealing ≥GG 2 disease. The optimal area cutpoint was ≥0.7 cm2, with an area under the curve of 0.671 (0.510–0.832). On logistic regression, area ≥0.7 cm2 was solely predictive of targeted biopsy revealing ≥GG 2 disease (odds ratio 6.5, 1.3–32.4, p=0.022).ConclusionsNodule area ≥0.7 cm2 may predict for transperineal-based targeted biopsies being positive for ≥GG 2 disease when 1–2 cores are taken. 相似文献
50.