全文获取类型
收费全文 | 19040篇 |
免费 | 1415篇 |
国内免费 | 31篇 |
专业分类
耳鼻咽喉 | 177篇 |
儿科学 | 702篇 |
妇产科学 | 604篇 |
基础医学 | 2540篇 |
口腔科学 | 209篇 |
临床医学 | 2481篇 |
内科学 | 3281篇 |
皮肤病学 | 297篇 |
神经病学 | 2249篇 |
特种医学 | 362篇 |
外科学 | 1761篇 |
综合类 | 182篇 |
现状与发展 | 1篇 |
一般理论 | 20篇 |
预防医学 | 2792篇 |
眼科学 | 185篇 |
药学 | 1210篇 |
1篇 | |
中国医学 | 15篇 |
肿瘤学 | 1417篇 |
出版年
2024年 | 35篇 |
2023年 | 230篇 |
2022年 | 357篇 |
2021年 | 779篇 |
2020年 | 485篇 |
2019年 | 679篇 |
2018年 | 757篇 |
2017年 | 575篇 |
2016年 | 646篇 |
2015年 | 652篇 |
2014年 | 794篇 |
2013年 | 1214篇 |
2012年 | 1725篇 |
2011年 | 1720篇 |
2010年 | 853篇 |
2009年 | 747篇 |
2008年 | 1158篇 |
2007年 | 1245篇 |
2006年 | 1098篇 |
2005年 | 1000篇 |
2004年 | 934篇 |
2003年 | 777篇 |
2002年 | 752篇 |
2001年 | 94篇 |
2000年 | 73篇 |
1999年 | 95篇 |
1998年 | 131篇 |
1997年 | 108篇 |
1996年 | 74篇 |
1995年 | 74篇 |
1994年 | 53篇 |
1993年 | 49篇 |
1992年 | 43篇 |
1991年 | 27篇 |
1990年 | 19篇 |
1989年 | 29篇 |
1988年 | 27篇 |
1987年 | 28篇 |
1986年 | 31篇 |
1985年 | 17篇 |
1984年 | 43篇 |
1983年 | 17篇 |
1982年 | 36篇 |
1981年 | 35篇 |
1980年 | 22篇 |
1979年 | 13篇 |
1978年 | 13篇 |
1977年 | 7篇 |
1976年 | 12篇 |
1975年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 255 毫秒
51.
A continuous sample introduction and separation scheme is presented as an alternative to the current slab gel and microfabricated chip technologies for biological separations. This new technique involves continuous sample introduction via a conventional small bore capillary coupled to a small dimension rectangular channel. Both free zone and size based separations have been carried out in the rectangular channel. Laser induced fluorescence and electrochemical detection schemes have been employed with this technique. Some of the areas this technology has been used to investigate include monitoring dynamic events from microenvironments, monitoring analytes over long periods of time, and performing DNA separations. 相似文献
52.
Ticks are ectoparasites of wild and domestic animals and humans, and are considered to be the most important arthropod vector of pathogens in North America. Development of vaccines directed against tick proteins may effect reduction of tick infestations and transmission of tick-borne pathogens. The limiting step for the development of tick vaccines has been the identification of tick protective antigens. Reverse vaccinology approaches aimed at reducing animal experimentation while allowing for the rapid screening of pools of potential tick vaccine candidates would greatly facilitate progress towards the development of tick vaccines. Herein, we describe the screening of Ixodes scapularis cDNAs for identification of tick protective antigens using RNA interference (RNAi). The results of the RNAi screening were similar to those obtained previously using expression library immunization and demonstrated that RNAi could serve as a more rapid and cost-effective tool for vaccine antigen discovery in ticks and in other nonmodel organisms. 相似文献
53.
Henderson LA Macey PM Macey KE Frysinger RC Woo MA Harper RK Alger JR Yan-Go FL Harper RM 《Journal of neurophysiology》2002,88(6):3477-3486
The Valsalva maneuver, a test frequently used to evaluate autonomic function, recruits discrete neural sites. The time courses of neural recruitment relative to accompanying cardiovascular and breathing patterns are unknown. We examined functional magnetic resonance imaging signal changes within the brain to repeated Valsalva maneuvers and correlated these changes with physiological trends. In 12 healthy subjects (age, 30-58 yr), a series of 25 volumes (20 gradient echo echo-planar image slices per volume) was collected using a 1.5-Tesla scanner during a 60-s baseline and 90-s challenge period consisting of three Valsalva maneuvers. Regions of interest were examined for signal intensity changes over baseline and challenge conditions in cardiorespiratory-related regions. In addition, whole brain correlations between signal intensity and heart rate and airway load pressure were performed on a voxel-by-voxel basis. Significant signal changes, correlated with the time course of load pressure and heart rate, emerged within multiple areas, including the amygdala and hippocampus, insular and lateral frontal cortices, dorsal pons, dorsal medulla, lentiform nucleus, and fastigial and dentate nuclei of the cerebellum. Signal intensities peaked early in the Valsalva maneuver within the hippocampus and amygdala, later within the dorsal medulla, pons and midbrain, and deep cerebellar nuclei, and last within the lentiform nuclei and the lateral prefrontal cortex. The ventral pontine signals increased during the challenge, but not in a fashion correlated to load pressure or heart rate. Sites showing little or no correlation included the vermis and medial prefrontal cortex. These data suggest an initiating component arising in rostral brain areas, a later contribution from cerebellar nuclei, basal ganglia, and lateral prefrontal cortex, and a role for the ventral pons in mediating longer term processes. 相似文献
54.
A Pavlovian conditioning model of tolerance emphasizes that an association between predrug cues and the systemic effects of the drug contributes to tolerance. On the basis of this model, established tolerance should be attenuated by external inhibition, i.e., by presentation of a novel, extraneous stimulus. This prediction was evaluated in the present experiment. Rats that were so tolerant to the hypothermic effect of ethanol that they evidenced no drug-induced decrease in temperature were presented with a bright strobe light following ethanol administration. The light precipitated a large decrease in temperature in these rats. These results provide further evidence that tolerance to the hypothermic effect of ethanol is, in part, mediated by learning. 相似文献
55.
Shipkin Rebecca Blackledge Kristin Jacob Jane Bosoy Frederick Schertz Katherine Bachmann Gloria 《Maternal and child health journal》2022,26(5):1005-1014
Maternal and Child Health Journal - This study assessed whether the use of a peer-to-peer educational book, written and illustrated by women who experienced common mental disorders (CMDs) in the... 相似文献
56.
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
57.
Amy E. Lawrence Lorraine I. Kelley-Quon Peter C. Minneci Katherine J. Deans Jennifer N. Cooper 《Journal of pediatric surgery》2021,56(5):868-874
BackgroundMost pediatric cholecystectomies are performed by adult general surgeons, but it is unclear whether outcomes differ by surgeon pediatric subspecialization, hospital procedure volume, or surgeon procedure volume. We aimed to determine whether higher hospital or surgeon laparoscopic cholecystectomy (LC) volume or surgeon pediatric subspecialization is associated with better outcomes after LC in children.MethodsWe performed a retrospective cohort study using statewide hospital discharge databases from the states of Florida, Georgia, and Iowa. We included children aged 4–18 years who underwent inpatient or outpatient LC for acute or chronic gallbladder disease in January 2010–August 2015.Propensity score weighting was used to estimate relationships between operative volumes or surgeon pediatric subspecialization and rates of readmission or emergency department (ED) visit within 30 days.ResultsA total of 5391 children were included (mean age 15.9 years, 81.6% female). Children operated on by surgeons with high LC volumes in hospitals with high LC volumes were less likely to experience a readmission or ED visit within 30 days (10.8% vs. 13.7%, p = 0.04). Additionally, children operated on by adult general surgeons in hospitals with high LC volumes were less likely to experience a readmission or ED visit within 30 days (10.9% vs. 13.8%, p = 0.03).ConclusionsChildren are less likely to be readmitted to the hospital or present to the ED after laparoscopic cholecystectomy if they receive their care from adult general surgeons at hospitals that frequently perform this procedure in both adults and children.Level of evidenceIII 相似文献
58.
59.
Woodson W. Smelser Joseph Hogan Randall Joshua Caldwell Katherine Glavin Eugene K. Lee Ajay Nangia Jeffrey M. Holzbeierlein 《Urologic oncology》2021,39(7):435.e23-435.e31
BackgroundPrior studies have demonstrated declines in androgen levels in men with cancer and patients undergoing anesthesia and surgery. In this study, we hypothesized that decreased serum androgen levels are prevalent in male patients undergoing radical cystectomy (RC) for bladder cancer and that it persists in the postoperative period. We characterized perioperative androgen hormonal profiles and examined for associated changes indicative of sarcopenia on computed tomography scans in men undergoing RC.MethodsWe implemented a prospective observational trial in men with newly diagnosed non-metastatic bladder cancer undergoing RC. Baseline pre-operative total testosterone (TT), free testosterone (FT), and luteinizing hormone (LH) were obtained on morning lab draws with 30 days of surgery. TT and FT were then repeated on postoperative days (POD) 2, 3, 30, and 90. The threshold for normal TT was defined as >300 ng/dl, consistent with the AUA Guidelines for Evaluation and Management of Testosterone Deficiency. We evaluated postoperative changes in weight and psoas muscle cross-sectional area using computed tomography scans to assess for sarcopenic changes.ResultsUnivariable statistical analysis was performed. 25 patients were enrolled. The mean patient age was 68.9 years. The mean pre-operative TT was 308 ng/dl, and 12/23 (52.5%) patients had low testosterone. Mean TT onPOD 2 and 3 were 166 ng/dl and 161 ng/dl, respectively (range 24–345). 19/20 (95%) of men who had morning lab draws had decreased TT. The mean TT at 30 days was 253 ng/dl with 37.5% of men having low TT. Mean TT at 90 days was 306 ng/dl. The mean FT levels were 43 ng/dl, 29.25 ng/dl, 28.2 ng/dl, 40.89 ng/dl, and 42.62 ng/dl at baseline, POD 2, POD 3, POD 30, and POD 90, respectively. Mean LH at baseline was 9.9 IU/L. Average weight loss at 30- and 90- days postop was -4.29 and -4.38 kilograms, respectively. Weight loss was persistent with only 3/23 (13%) returning to their presurgery weight by 90 days. Despite significant declines in weight and perioperative TT, no significant differences in psoas muscle cross-sectional area were observed (net change -92 mm2, P= 0.13)ConclusionsPerioperative disruption of androgen levels is prevalent in men undergoing RC. Our trial demonstrates a pre-op, immediate postop, 30- and 90-day postoperative prevalence of low TT of 52%, 95%, 63%, and 37.5%, respectively. Significant changes in baseline weight were noted, although no significant changes in psoas muscle cross-sectional area were observed, limiting conclusions regarding a link between changes in androgens and sarcopenia in this setting. 相似文献
60.
Hillarey K. Stone Katherine VandenHeuvel Alexander Bondoc Francisco X. Flores David K. Hooper Charles D. Varnell Jr 《American journal of transplantation》2021,21(12):4061-4067
Primary hyperoxaluria type 1 is a rare inherited disorder caused by abnormal liver glyoxalate metabolism leading to overproduction of oxalate, progressive kidney disease, and systemic oxalosis. While the disorder typically presents with nephrocalcinosis, recurrent nephrolithiasis, and/or early chronic kidney disease, the diagnosis is occasionally missed until it recurs after kidney transplant. Allograft outcomes in these cases are typically very poor, often with early graft loss. Here we present the case of a child diagnosed with primary hyperoxaluria type 1 after kidney transplant who was able to maintain kidney function, thanks to aggressive renal replacement therapy as well as initiation of a new targeted therapy for this disease. This case highlights the importance of having a high index of suspicion for primary hyperoxaluria in patients with chronic kidney disease and nephrocalcinosis/nephrolithiasis or with end stage kidney disease of uncertain etiology, as initiating therapies early on may prevent poor outcomes. 相似文献