首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3615篇
  免费   154篇
  国内免费   8篇
耳鼻咽喉   27篇
儿科学   234篇
妇产科学   49篇
基础医学   303篇
口腔科学   66篇
临床医学   261篇
内科学   888篇
皮肤病学   47篇
神经病学   179篇
特种医学   77篇
外国民族医学   1篇
外科学   744篇
综合类   105篇
预防医学   145篇
眼科学   162篇
药学   280篇
中国医学   22篇
肿瘤学   187篇
  2024年   2篇
  2023年   29篇
  2022年   56篇
  2021年   159篇
  2020年   86篇
  2019年   102篇
  2018年   103篇
  2017年   75篇
  2016年   105篇
  2015年   117篇
  2014年   146篇
  2013年   193篇
  2012年   284篇
  2011年   293篇
  2010年   190篇
  2009年   140篇
  2008年   247篇
  2007年   251篇
  2006年   212篇
  2005年   191篇
  2004年   183篇
  2003年   165篇
  2002年   150篇
  2001年   37篇
  2000年   33篇
  1999年   26篇
  1998年   29篇
  1997年   17篇
  1996年   10篇
  1995年   15篇
  1994年   11篇
  1993年   12篇
  1992年   8篇
  1991年   10篇
  1990年   12篇
  1989年   14篇
  1988年   8篇
  1987年   4篇
  1986年   5篇
  1985年   5篇
  1984年   7篇
  1983年   8篇
  1982年   5篇
  1981年   5篇
  1980年   3篇
  1974年   2篇
  1973年   2篇
  1972年   2篇
  1971年   3篇
  1944年   1篇
排序方式: 共有3777条查询结果,搜索用时 31 毫秒
21.
PurposeWe developed and validated a measure that assesses the latent construct of sexual and reproductive empowerment among adolescents and young adults. A specific measure for this group is critical because of their unique life stage and circumstances, which often includes frequent changes in sexual partners and involvement from parents in decision-making.MethodsAfter formative qualitative research, a review of the literature, and cognitive interviews, we developed 95 items representing nine dimensions of sexual and reproductive empowerment. Items were then fielded among a national sample of young people aged 15–24 years, and those who identified as sexually active completed a 3-month follow-up survey. We conducted psychometric analysis and scale validation.ResultsExploratory factor analysis on responses from 1,117 participants resulted in the Sexual and Reproductive Empowerment Scale for Adolescents and Young Adults, containing 23 items captured by seven subscales: comfort talking with partner; choice of partners, marriage, and children; parental support; sexual safety; self-love; sense of future; and sexual pleasure. Validation using logistic regression demonstrated that the subscales were consistently associated with sexual and reproductive health information and access to sexual and reproductive health services measured at baseline and moderately associated with the use of desired contraceptive methods at 3-month follow-up.ConclusionsThe Sexual and Reproductive Empowerment Scale for Adolescents and Young Adults is a new measure that assesses young people’s empowerment regarding sexual and reproductive health. It can be used by researchers, public health practitioners, and clinicians to measure sexual and reproductive empowerment among young people.  相似文献   
22.
BackgroundGiven the morbidity, mortality, and financial burden associated with venous thromboembolism (VTE) after TKA, orthopaedic providers continually seek to identify risk factors associated with this devastating complication. The association between perioperative transfusion status and VTE risk has not been thoroughly explored, with previous studies evaluating this relationship being limited in both generalizability and power.Questions/purposesTherefore, we sought to determine whether perioperative transfusions were associated with an increased risk of (1) pulmonary embolism (PE) or (2) deep vein thrombosis (DVT) after primary TKA in a large, multi-institutional sample.MethodsThe American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database was implemented for our analysis. The definitions of complications, such as DVT and PE, and risk adjustment validation is monitored by the central ACS NSQIP office to ensure participating hospitals are adhering to the same guidelines to log patients. Additionally, both preoperative and intraoperative/72 hour postoperative transfusion status is included for all patients. Therefore, ACS NSQIP was determined to be the most appropriate database for our analysis. All patients who underwent primary TKA between 2011 and 2018 were identified using Current Procedural Terminology code 27447. Primary TKAs designated as “non-elective” were excluded, thereby providing a cohort composed solely of patients undergoing unilateral primary elective TKA for further analysis. The final analysis included 333,463 patients undergoing TKA (mean age 67 ± 9 years, 62% female). Preoperative transfusions were received by < 0.01% (48 of 333,463) of the patients, while 4% (14,590 of 333,463) received a transfusion within the interim between the start of surgery up to 72 hours postoperatively. All missing values were imputed through multiple imputation by chained equation to avoid variable availability-based selection and the subsequent listwise deletion-associated bias in the estimate of parameters. A multivariable logistic regression analysis was conducted using variables identified in a univariate model to calculate adjusted odds ratios and 95% confidence intervals for risk factors associated with symptomatic DVT and/or PE. For variables that maintained significance in the multivariable model, an additional model without confounders was used to generate fully adjusted ORs and 95% CIs. A propensity score matched comparison between recipients versus nonrecipients (1:1) of transfusion (preoperative and intraoperative/72 hours postoperative) was then conducted to evaluate the independent association between DVT/PE development and patients’ transfusion status. Significance was determined at a p value < 0.05.ResultsAdjusted multivariable regression analysis accounting for patient age, sex, race, BMI, American Society of Anesthesiologists (ASA) class and baseline comorbidities demonstrated the absence of an association between preoperative (OR 1.75 [95% CI 0.24 to 12.7]; p = 0.58) or intraoperative/72 hours postoperative (OR 1.12 [95% CI 0.93 to 1.35]; p = 0.23) transfusions and higher odds of developing PE. Similar findings were demonstrated after propensity score matching. Although multivariable regression demonstrated the absence of an association between preoperative transfusion and the odds of developing DVT within the 30-day postoperative period (OR 1.85 [95% CI 0.43 to 8.05]; p = 0.41), intraoperative/postoperative transfusion was associated with higher odds of DVT development (OR 3.68 [95% CI 1.14 to 1.53]; p < 0.001) relative to transfusion naïve patients. However, this significance was lost after propensity score matching.ConclusionAfter controlling for various potential confounding variables such as ASA Class, age, anesthesia type, and BMI, the receipt of an intra- or postoperative transfusion was found to be associated with an increased risk of DVT. Our findings should encourage orthopaedic providers to strictly adhere to blood management protocols, further tighten transfusion eligibility, and adjust surgical approach and implant type to reduce the incidence of transfusion among patients with other DVT risk factors. Additionally, our findings should encourage a multidisciplinary approach to VTE prophylaxis and prevention, as well as to blood transfusion guideline adherence, among all providers of the care team.Level of EvidenceLevel III, therapeutic study.  相似文献   
23.
Background/Purpose of the StudyC-arm-guided biopsy is a safe and effective technique for evaluating TB spine and is useful in planning therapy. The purpose of this study was to find a correlation between clinically and radiologically suspected TB spine and C-arm image-guided biopsy-proven cases and to study the complications encountered.MethodsAfter evaluating the clinical, laboratory, X-ray and MRI findings, 92 patients with provisionally diagnosed tubercular spine were subjected to C-arm image-guided biopsy.ResultsAmong our 92 cases, histopathology was positive in 55 cases (59.78%). Out of these 55 histologically positive cases, CBNAAT was positive in 42 cases and negative in the rest 13 cases. Overall, among the 92 cases, CBNAAT was positive in 51(55.43%) of cases, and out of these, histopathology turned out to be positive in 42 of cases. Out of 41 cases with negative CBNAAT, histopathology was suggestive of tuberculosis in 13. The strength of agreement between CBNAAT and histopathology was statistically significant (p < 0.0001; kappa = 0.511). No complication such as bleeding, nerve/cord injury, infection, injury to aorta or pneumothorax was encountered during and after the C-arm biopsy in any case.ConclusionC-arm image-guided biopsy is reasonably accurate and should be used as a tool for diagnosis of TB spine. We recommend histopathological examination as a key component for the diagnosis of TB spine, as it is precise and consumes relatively shorter time. CBNAAT is more rapid but is not a substitute for histopathology for spine TB diagnosis.  相似文献   
24.
Individualized posttransplant immunosuppression is hampered by suboptimal monitoring strategies. To validate the utility of urinary CXCL10/Cr immune monitoring in children, we conducted a multicenter prospective observational study in children <21 years with serial and biopsy-associated urine samples (n = 97). Biopsies (n = 240) were categorized as normal (NOR), rejection (>i1t1; REJ), indeterminate (IND), BKV infection, and leukocyturia (LEU). An independent pediatric cohort of 180 urines was used for external validation. Ninety-seven patients aged 11.4 ± 5.5 years showed elevated urinary CXCL10/Cr in REJ (3.1, IQR 1.1, 16.4; P < .001) and BKV nephropathy (median = 5.6, IQR 1.3, 26.9; P < .001) vs. NOR (0.8, IQR 0.4, 1.5). The AUC for REJ vs. NOR was 0.76 (95% CI 0.66–0.86). Low (0.63) and high (4.08) CXCL10/Cr levels defined high sensitivity and specificity thresholds, respectively; validated against an independent sample set (AUC = 0.76, 95% CI 0.66–0.86). Serial urines anticipated REJ up to 4 weeks prior to biopsy and declined within 1 month following treatment. Elevated mean CXCL10/Cr was correlated with first-year eGFR decline (ρ = −0.37, P ≤ .001), particularly when persistently exceeding ≥4.08 (ratio = 0.81; P < .04). Useful thresholds for urinary CXCL10/Cr levels reproducibly define the risk of rejection, immune quiescence, and decline in allograft function for use in real-time clinical monitoring in children.  相似文献   
25.
Lung transplant recipients are at high risk for herpes zoster and preventive measures are a significant unmet need. We investigated the safety and immunogenicity of two doses of a recombinant zoster vaccine (RZV) in lung transplant recipients (≥50 years). We enrolled 50 patients of which 49 received at least one vaccine dose. Anti-glycoprotein E (gE) antibody levels (n = 43) increased significantly compared to baseline (median optical density [OD] 1.96; interquartile range [IQR]: 1.17–2.89) after the first (median OD 3.41, IQR 2.54–3.81, p < .0001) and second vaccine dose (median OD 3.63, IQR 3.39–3.86, p < .0001). gE-specific polyfunctional CD4+ T cell frequencies (n = 38) also increased from baseline (median 85 per 106 CD4+ T cells; IQR: 46–180) to the first (median 128 per 106 CD4+ T cells; IQR: 82–353; p = .023) and after the second dose (median 361 per 106 CD4+ T cells; IQR: 146–848; p < .0001). Tenderness (83.0%; 95%CI: 69.2–92.4%) and redness (31.9%; 95%CI: 19.1–47.1%) at injection site were common. One rejection episode within 3 weeks of vaccination was observed. This is the first study demonstrating that RZV was safe and elicited significant humoral and cell-mediated immunity in lung transplant recipients. RZV is a new option for the prevention of shingles in this population.  相似文献   
26.
The authors describe their experience with maintenance electroconvulsive therapy administered to 10 patients, using an abbreviated or a full maintenance schedule. Recommendation for either form of treatment was made on clinical grounds. Patients with major depressive episodes with delusional features appear to respond best to maintenance ECT.  相似文献   
27.
28.
Objectives. To assess the role of clinical parameters and pathologic stage in predicting a positive vesicourethral anastomosis (VUA) biopsy in patients with a rising prostate-specific antigen (PSA) level after radical prostatectomy.Methods. Forty-five patients were referred for a rising PSA level after radical prostatectomy. Transrectal ultrasound evaluation included visualization of the VUA and VUA quadrant biopsies. The rate of positive biopsies (per core and per patient) was correlated with race, PSA level, and the radical prostatectomy pathologic stage.Results. Overall, 53% of patients had a positive biopsy. In multivariate analysis, the dominant independent and synergistic clinical parameters determining positive biopsy rates were a PSA greater than 1 ng/mL at the time of biopsy and the pathologic stage (P = 0.04 and P = 0.02, respectively). Using a PSA cutoff point of 1.0 ng/mL, those patients with organ-confined disease and a PSA of 1.0 ng/mL or less showed no positive cancer cores (low-risk group). Conversely, 89% of patients with extraprostatic extension and a PSA greater than 1.0 ng/mL had a positive biopsy (P <0.01) (high-risk group). Patients with organ-confined disease and a PSA greater than 1.0 ng/mL or extraprostatic extension and a PSA 1.0 ng/mL or less (intermediate-risk group) had a significantly higher chance of having residual cancer than the low-risk group (P <0.025).Conclusions. The PSA level at the time of biopsy and the pathologic stage of the radical prostatectomy specimen were the strongest determinants of a positive biopsy. A combination of PSA and pathologic stage is useful for decisions regarding VUA biopsy. Patients with organ-confined disease and a PSA of 1.0 ng/mL or less do not appear to benefit from a VUA biopsy, and patients with extraprostatic extension and a PSA greater than 1.0 ng/mL have such a high probability (89%) of local recurrence at the VUA that biopsy may be unnecessary. It appears that VUA biopsy can be restricted to those patients with an intermediate risk (organ-confined disease with PSA greater than 1 ng/mL or extraprostatic extension with a PSA less than 1 ng/mL).  相似文献   
29.
A novel approach for immunocontraception by intervention of local cell mediated immunity in the reproductive system by using single intrauterine application of neem oil has been described earlier. The reversible block in fertility was reported to last for 107–180 days in female Wistar rats (Upadhyay et al., 1990. Antifertility effects of neem oil by single intrauterine administration: A novel method of contraception. Proceedings Of The Royal Society Of London B 242, 175–180) and 7–11 months in monkeys (Upadhyay et al., 1994. Long term contraceptive effects of intrauterine neem treatment (IUNT) in bonnet monkeys: An alternative to intrauterine contraceptive devices. Contraception 49, 161–167). The present study, describes the identification and characterization of the biologically active fraction from neem seeds (Azadirachta indica A. Juss. Family Meliaceae), responsible for the above activity in adult female Wistar rats. Initial studies with the mechanically extracted oil and solvent extracts of neem seeds have revealed that the antifertility activity was present in constituents of low to intermediate polarity. A hexane extract of neem seeds was reported to be biologically active (Garg et al., 1994. Comparison of extraction procedures on the immunocontraceptive activity of neem seed extracts. Journal of Ethnopharmacology 22, 87–92). Subsequently, hexane extract was sequentially fractionated through the last active fraction using various separation techniques and tested for antifertility activity at each step. Preparative HPLC was used for isolating individual components of the active fraction in quantities, sufficient for characterization. An analytical HPLC method was developed for standardization of the fraction. The active fraction was identified to be a mixture of six components, which comprises of saturated, mono and di-unsaturated free fatty acids and their methyl esters. Dose response study was performed with the last active fractions. The antifertility activity with the active fraction was reversible in nature and it was completely active until 5% concentration. There was no systemic toxic effect following the administration of the active fraction. This study, for the first time, proposes an active fraction from neem seeds, responsible for long term and reversible blocking of fertility after a single intrauterine administration with high efficacy.  相似文献   
30.
According to DSM IV criteria, sleep disturbances are incorporated in the definition of post-traumatic stress disorder (PTSD). These include the re-experiencing symptoms (nightmares, criteria B) and a hyperarousal state (difficulty initiating and maintaining sleep, criteria D). PTSD patients commonly complain of sleep disturbances. Moreover, insomnia, restless sleep and trauma-related dreams might be the primary complaint of some patients. However, although subjective sleep disturbances are considered characteristic of PTSD, sleep laboratory studies have provided inconsistent evidence of objective sleep disorders. A variety of sleep architectures and sleep patterns has been reported in PTSD. However, only a few studies have controlled for comorbidities. Thus, uncertainty exists to what extent the sustained complaints of sleep disturbances in chronic PTSD are specifically related to the impact of exposure to traumatic stress, or rather are a consequence of comorbid disorders. Specific changes in REM sleep suggest a pathophysiologic role of REM sleep abnormality in PTSD (e.g. anxiety dreams, increased REM density, exaggerated startle response, decreased dream recall and elevated awakening thresholds from REM sleep). However, again, studies have failed to show consistent changes in percentage of REM sleep or in REM latency. There might be a coexistence of pressure to REM along with inhibitory forces of REM that result in high variability of REM parameters across patients. Alternatively, changes in REM sleep might reflect the effect of comorbid psychiatric disorders that results in inconsistent findings between patients. The current review tries to address these issues based on recent studies carried out in this field.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号