全文获取类型
收费全文 | 8701篇 |
免费 | 918篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 85篇 |
儿科学 | 280篇 |
妇产科学 | 164篇 |
基础医学 | 1177篇 |
口腔科学 | 166篇 |
临床医学 | 936篇 |
内科学 | 1639篇 |
皮肤病学 | 157篇 |
神经病学 | 663篇 |
特种医学 | 253篇 |
外科学 | 1284篇 |
综合类 | 122篇 |
一般理论 | 11篇 |
预防医学 | 1171篇 |
眼科学 | 181篇 |
药学 | 625篇 |
中国医学 | 4篇 |
肿瘤学 | 719篇 |
出版年
2023年 | 99篇 |
2022年 | 178篇 |
2021年 | 443篇 |
2020年 | 252篇 |
2019年 | 368篇 |
2018年 | 430篇 |
2017年 | 298篇 |
2016年 | 297篇 |
2015年 | 314篇 |
2014年 | 441篇 |
2013年 | 510篇 |
2012年 | 764篇 |
2011年 | 724篇 |
2010年 | 387篇 |
2009年 | 266篇 |
2008年 | 483篇 |
2007年 | 371篇 |
2006年 | 369篇 |
2005年 | 332篇 |
2004年 | 346篇 |
2003年 | 243篇 |
2002年 | 268篇 |
2001年 | 110篇 |
2000年 | 82篇 |
1999年 | 95篇 |
1998年 | 50篇 |
1997年 | 53篇 |
1996年 | 49篇 |
1995年 | 38篇 |
1994年 | 42篇 |
1992年 | 40篇 |
1991年 | 47篇 |
1990年 | 62篇 |
1989年 | 59篇 |
1988年 | 49篇 |
1987年 | 38篇 |
1986年 | 34篇 |
1985年 | 50篇 |
1984年 | 30篇 |
1983年 | 26篇 |
1979年 | 33篇 |
1978年 | 37篇 |
1977年 | 22篇 |
1976年 | 36篇 |
1975年 | 21篇 |
1974年 | 23篇 |
1973年 | 39篇 |
1972年 | 32篇 |
1970年 | 22篇 |
1969年 | 30篇 |
排序方式: 共有9637条查询结果,搜索用时 15 毫秒
61.
Burrows Tanya Dee; King Ashley; Smith S.K.; Loke Y.W. 《Molecular human reproduction》1995,1(7):341-352
At the time of implantation, the extracellular matrix proteinslaminin and fibronectin are abundant in the decidua and aredistributed pericellularly around each individual stromal cell.First trimester human trophoblast expresses both laminin andfibronectin receptors, specifically the 1ß1 5ß16ß1 and 6ß4 integrin heterodimers. In thisstudy we have demonstrated that in-vitro adhesion of first trimesterhuman trophoblast to purified extracellular matrix proteinsand to purified decidual stromal cell monolayers can be inhibitedby monoclonal antibodies directed against appropriate integrinsubunits and by synthetic peptides containing an arginine-glycine-asparticacid sequence. Monoclonal antibodies (mAbs) to the 5 and ß1integrin subunits and a synthetic peptide significantly inhibitedadhesion to fibronectin. Binding of trophoblast to laminin wasblocked with mAbs to the 6 and ß1 but not 1 and ß4integrinsubunits. Similarly, integrin-mediated adhesion to monolayersof decidual stromal cells could be blocked with mAbs to the5, 6, ß6 and ß4 integrin subunits. Integrin-mediatedsignal transduction in normal and malignant trophoblast wasinvestigated by Western blotting. A 115 kDa protein was themajor tyrosine phosphorylated protein detected in trophoblastafter binding to laminin or fibronectin. The profile of tyrosinephosphorylated proteins differed for malignant trophoblast. integrins/matrix/signal transduction/trophoblast 相似文献
62.
Reactivation of genital herpes simplex virus type 2 infection in asymptomatic seropositive persons 总被引:23,自引:0,他引:23
Wald A Zeh J Selke S Warren T Ryncarz AJ Ashley R Krieger JN Corey L 《The New England journal of medicine》2000,342(12):844-850
BACKGROUND: Most persons who have serologic evidence of infection with herpes simplex virus (HSV) type 2 (HSV-2) are asymptomatic. Historically, it has been assumed that these persons have less frequent viral reactivation than those with symptomatic infection. METHODS: We conducted a prospective study to investigate genital shedding of HSV among 53 subjects who had antibodies to HSV-2 but who reported having no history of genital herpes, and we compared their patterns of viral shedding with those in a similar cohort of 90 subjects with symptomatic HSV-2 infection. Genital secretions of the subjects in both groups were sampled daily and cultured for HSV for a median of 94 days. RESULTS: HSV was isolated from the genital mucosa in 38 of the 53 HSV-2-seropositive subjects (72 percent) who reported no history of genital herpes, and HSV DNA was detected by the polymerase-chain-reaction assay in cultures prepared from genital mucosal swabs in 6 additional subjects. The rate of subclinical shedding of HSV in the subjects with no reported history of genital herpes was similar to that in the subjects with such a history (3.0 percent vs. 2.7 percent). Of the 53 subjects who had no reported history of genital herpes, 33 (62 percent) subsequently reported having typical herpetic lesions; the duration of their recurrences in these subjects was shorter (median, three days vs. five days; P<0.001) and the frequency lower (median, 3.0 per year vs. 8.2 per year; P<0.001) than in the 90 subjects with previously diagnosed symptomatic infection. Only 1 of these 53 subjects had no clinical or virologic evidence of HSV infection. CONCLUSIONS: Seropositivity for HSV-2 is associated with viral shedding in the genital tract, even in subjects with no reported history of genital herpes. 相似文献
63.
Clinical correlates of index values in the focus HerpeSelect ELISA for antibodies to herpes simplex virus type 2 (HSV-2). 总被引:2,自引:0,他引:2
Rhoda Ashley Morrow Elizabeth Krantz David Friedrich Anna Wald 《Journal of clinical virology》2006,36(2):141-145
BACKGROUND: Clinical correlates of HerpeSelect ELISA index values are poorly understood. OBJECTIVES: This study was designed to determine the effects of time of infection, test variability, and antibody avidity on index values. STUDY DESIGN: Sera (N=313) from 81 patients with new HSV-2 infections and 236 sera from 32 patients with long-standing (median 11.3 years) HSV-2 were tested by HerpeSelect HSV-2 ELISA. High positive, low positive and negative controls were run on 42 test plates to establish test variability. RESULTS: Index values tended to rise after infection, peaking a median of 9-10 weeks post-infection (range 8-323 days). Of 32 patients with established HSV-2 infections, 7 (22%) had at least one low index value (>1.1 to < or =3.5), and one had a transient seroreversion event. Test variability of index values was substantially lower than inter- or intra-patient variability. Median antibody avidity was higher in sera with high versus low index values in established infections, but unrelated to index value in patients with early infections. CONCLUSIONS: Index values or index value changes are not absolute indicators of early versus established HSV-2 infection or solely a function of test variability. Low antibody avidity may contribute to low index values once infection is established. 相似文献
64.
Jean-Baptiste Bouillon-Minois Marion Trousselard David Thivel Brett Ashley Gordon Jeannot Schmidt Fars Moustafa Charlotte Oris Frdric Dutheil 《Nutrients》2021,13(3)
Introduction: Ghrelin is an orexigenic hormone which favors food-seeking behavior and has been postulated to be a biomarker of stress. We conducted a systematic review and meta-analysis on the evolution of ghrelin levels following acute stress. Methods: The PubMed, Cochrane Library, Embase, and ScienceDirect databases were searched for studies reporting ghrelin levels before and after acute stress in humans. Results: We included ten studies for a total of 348 patients. Acute stress (intervention) was always in a laboratory. Acute stress was psychological (Trier Social Stress Test), physical, or mixed (cold pressure test). The overall meta-analysis demonstrated an increase in ghrelin after the stress intervention (ES = 0.21, 95CI 0.09 to 0.34) compared with baseline levels. Stratification by time demonstrated an acute increase in ghrelin levels in the five minutes immediately following the initiation of stress (0.29, 0.10 to 0.48) but without any difference after. Obese individuals had a more significant (ES = 0.51, 95CI 0.18 to 0.84) and prolonged increase in ghrelin levels for up to 45 min compared with non-obese individuals who had a significant increase only five minutes after stress. Moreover, the ghrelin levels increased in response to stress with BMI (coefficient 0.028, 0.01 to 0.49; p = 0.013) and decreased with the time after the stress intervention (coefficient -0.007, −0.014 to −0.001; p = 0.025). Conclusion: Ghrelin is a biomarker of stress, with a short-term increase following acute stress. Obese individuals have both a higher and prolonged response, emphasizing the link between obesity and stress. 相似文献
65.
Aaron Persinger Matthew Butawan Martina Faietti Ashley Pryke Kyley Rose Marie van der Merwe Richard J. Bloomer Melissa J. Puppa 《Nutrients》2021,13(5)
Time-restricted feeding (TRF) is becoming a popular way of eating in physically active populations, despite a lack of research on metabolic and performance outcomes as they relate to the timing of food consumption in relation to the time of exercise. The purpose of this study was to determine if the timing of feeding/fasting after exercise training differently affects muscle metabolic flexibility and response to an acute bout of exercise. Male C57BL/6 mice were randomized to one of three groups for 8 weeks. The control had ad libitum access to food before and after exercise training. TRF-immediate had immediate access to food for 6 h following exercise training and the TRF-delayed group had access to food 5-h post exercise for 6 h. The timing of fasting did not impact performance in a run to fatigue despite TRF groups having lower hindlimb muscle mass. TRF-delayed had lower levels of muscle HSL mRNA expression and lower levels of PGC-1α expression but displayed no changes in electron transport chain enzymes. These results suggest that in young populations consuming a healthy diet and exercising, the timing of fasting may not substantially impact metabolic flexibility and running performance. 相似文献
66.
Birthing can be an empowering experience for women. Within many Indigenous cultures around the world, birth is a ceremony to celebrate new life, acknowledging the passing from the spiritual world into the physical world. While initiatives to “indigenize” health care have been made, this paper argues that the United Nations Declaration on the Rights of Indigenous Peoples and the United Nations Sustainable Development Goals contain frameworks for Indigenous rights that include the right to incorporate Indigenous childbirth ceremonies into clinical practice. Examining the importance of birthplace, this paper details a current movement in Manitoba, Canada, to “bring birth home,” which recognizes that the determinants of health experienced in the early stages of a child’s development can have health implications for an individual’s future. 相似文献
67.
Effect of Condoms on Reducing the Transmission of Herpes Simplex Virus Type 2 From Men to Women 总被引:21,自引:1,他引:20
Wald Anna; Langenberg Andria G. M.; Link Katherine; Izu Allen E.; Ashley Rhoda; Warren Terri; Tyring Stephen; Douglas John M. Jr; Corey Lawrence 《JAMA》2001,285(24):3100-3106
Context Herpes simplex virus type 2 (HSV-2) is one of the most common sexually transmitted infections in the United States. No prospective study has shown the ability of condoms to reduce transmission of HSV-2. Objective To evaluate risk factors for HSV-2 acquisition and efficacy of condoms in prevention of HSV-2 transmission. Design Analysis of data from a randomized, double-blind, placebo-controlled trial conducted December 13, 1993, to June 28, 1996, of an ineffective candidate HSV-2 vaccine with 18 months of follow-up. Setting Eighteen clinical trial centers in the United States. Participants A total of 528 monogamous couples discordant for HSV-2 infection, including an HSV-2susceptible population of 261 men and 267 women. Main Outcome Measure Acquisition of HSV-2 infection by susceptible partners, compared with those remaining free of HSV-2 with regard to demographic characteristics, sexual activity, and condom use. Results Twenty-six women (9.7%) vs 5 men (1.9%) acquired HSV-2, for a rate per 10 000 sex acts (episodes of sexual intercourse) of 8.9 vs 1.5, respectively (P<.001). In multivariable analysis, younger age (adjusted hazard ratio [HR] per 5 years, 1.57; 95% confidence interval [CI], 1.22-2.04), seropositivity for HSV-1 and HSV-2 vs HSV-2 alone in the source partner (adjusted HR, 2.34; 95% CI, 1.14-4.82), and more frequent sexual activity (adjusted HR per additional sex act per week, 1.10; 95% CI, 1.01-1.19) were associated with higher risk of HSV-2 acquisition. Condom use during more than 25% of sex acts was associated with protection against HSV-2 acquisition for women (adjusted HR, 0.085; 95% CI, 0.01-0.67) but not for men (adjusted HR, 2.02; 95% CI, 0.32-12.50). Risk of HSV-2 transmission declined from 8.5 per 100 person-years in the initial 150-day interval to 0.9 per 100 person-years in the final 150-day interval (P = .002 for trend), concurrent with a decrease in sexual activity and proportion of sex acts occurring when the source partner had genital lesions. Conclusions Condom use offers significant protection against HSV-2 infection in susceptible women. Changes in sexual behavior, correlated with counseling about avoiding sex when a partner has lesions, were associated with reduction in HSV-2 acquisition over time. These data suggest that identification of discordant couples can reduce transmission of HSV-2, especially for heterosexual couples in which the male partner has HSV-2 infection. 相似文献
68.
69.
Matthew S. Austin Blair S. Ashley Nicholas A. Bedard Hari P. Bezwada Charles P. Hannon Yale A. Fillingham Yogesh V. Kolwadkar Harold W. Rees Matthew J. Grosso Erik N. Zeegen 《The Journal of arthroplasty》2021,36(8):2665-2673.e8
BackgroundThe prevalence of total joint arthroplasty (TJA) in the United States has drawn the attention of health care stakeholders. The payers have also used a variety of strategies to regulate the medical necessity of these procedures. The purpose of this study was to examine the level of evidence of the coverage policies being used by commercial payers in the United States.MethodsThe references of the coverage policies of four commercial insurance companies were reviewed for type of document, level of evidence, applicability to a TJA population, and success of nonoperative treatment in patients with severe degenerative joint disease.Results282 documents were reviewed. 45.8% were primary journal articles, 14.2% were level I or II, 41.2% were applicable to patients who were candidates for TJA, and 9.9% discussed the success of nonoperative treatment in patients who would be candidates for TJA.ConclusionMost of the references cited by commercial payers are of a lower level of scientific evidence and not applicable to patients considered to be candidates for TJA. This is relatively uniform across the reviewed payers. The dearth of high-quality literature cited by commercial payers reflects the lack of evidence and difficulty in conducting high level studies on the outcomes of nonoperative versus operative treatment for patients with severe, symptomatic osteoarthritis. Patients, surgeons, and payers would all benefit from such studies and we encourage professional societies to strive toward that end through multicenter collaboration. 相似文献
70.
Linda P. Hunt Ashley W. Blom Gulraj S. Matharu Setor K. Kunutsor Andrew D. Beswick J. Mark Wilkinson Michael R. Whitehouse 《The Journal of arthroplasty》2021,36(2):471-477.e6
BackgroundTo determine unicompartmental (UKR) and total knee replacement (TKR) revision rates, compare UKR revision rates with what they would have been had they received TKR instead, and assess subsequent re-revision and 90-day mortality rates.MethodsUsing National Joint Registry data, we estimated UKR and TKR revision and mortality rates. Flexible parametric survival modeling (FPM) was used to model failure in TKR and make estimates for UKR. Kaplan-Meier estimates were used to compare cumulative re-revision for revised UKRs and TKRs.ResultsTen-year UKR revision rates were 2.5 times higher than expected from TKR, equivalent to 70 excess revisions/1000 cases within 10 years (5861 excess revisions in this cohort). Revision rates were 2.5 times higher for the highest quartile volume UKR surgeons compared to the same quartile for TKR and 3.9 times higher for the lowest quartiles respectively. Re-revision rates of revised TKRs (10 years = 17.5%, 95% confidence interval [CI] 16.4-18.7) were similar to revised UKRs (15.2%, 95% CI 13.4-17.1) and higher than revision rates following primary TKR (3.3%, 95% CI 3.1-3.5). Ninety-day mortality rates were lower after UKR compared with TKR (0.08% vs 0.33%) and lower than predicted had UKR patients received a TKR (0.18%), equivalent to 1 fewer death per 1000 cases.ConclusionUKR revision rates were substantially higher than TKR even when demographics and caseload differences were accounted for; however, fewer deaths occur after UKR. This should be considered when forming treatment guidelines and commissioning services. Re-revision rates were similar between revised UKRs and TKRs, but considerably higher than for primary TKR, therefore UKR cannot be considered an intermediate procedure. 相似文献