全文获取类型
收费全文 | 8940篇 |
免费 | 499篇 |
国内免费 | 45篇 |
专业分类
耳鼻咽喉 | 92篇 |
儿科学 | 314篇 |
妇产科学 | 279篇 |
基础医学 | 841篇 |
口腔科学 | 288篇 |
临床医学 | 842篇 |
内科学 | 2101篇 |
皮肤病学 | 248篇 |
神经病学 | 707篇 |
特种医学 | 322篇 |
外科学 | 1543篇 |
综合类 | 141篇 |
一般理论 | 7篇 |
预防医学 | 527篇 |
眼科学 | 213篇 |
药学 | 506篇 |
中国医学 | 37篇 |
肿瘤学 | 476篇 |
出版年
2024年 | 12篇 |
2023年 | 112篇 |
2022年 | 210篇 |
2021年 | 434篇 |
2020年 | 285篇 |
2019年 | 374篇 |
2018年 | 361篇 |
2017年 | 267篇 |
2016年 | 273篇 |
2015年 | 288篇 |
2014年 | 412篇 |
2013年 | 438篇 |
2012年 | 759篇 |
2011年 | 754篇 |
2010年 | 425篇 |
2009年 | 367篇 |
2008年 | 530篇 |
2007年 | 549篇 |
2006年 | 453篇 |
2005年 | 419篇 |
2004年 | 352篇 |
2003年 | 333篇 |
2002年 | 276篇 |
2001年 | 92篇 |
2000年 | 82篇 |
1999年 | 77篇 |
1998年 | 45篇 |
1997年 | 47篇 |
1996年 | 39篇 |
1995年 | 26篇 |
1994年 | 18篇 |
1993年 | 31篇 |
1992年 | 30篇 |
1991年 | 34篇 |
1990年 | 29篇 |
1989年 | 19篇 |
1988年 | 25篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 27篇 |
1984年 | 27篇 |
1983年 | 15篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1974年 | 7篇 |
1973年 | 6篇 |
排序方式: 共有9484条查询结果,搜索用时 13 毫秒
51.
Amir Shmueli Mario Baras Charles L. Sprung 《Health services & outcomes research methodology》2004,5(3-4):163-174
Intensive Care Units (ICU) are one of the most powerful and expensive technologies within inpatient care. However, its effect
on survival is still an issue under discussion. The objective of this paper is to assess the effect of General ICU on in-hospital
survival. We assessed the effect of ICU on survival using Linear and Probit regressions. Since admission to IC is not random
and depends on unobserved (to the researcher) heterogeneity, we reassessed the IC effect by Instrumental Variables (IV) and
Bivariate Probit techniques, using crowding in the IC unit as an instrument. The results show that a simple Probit of the
IC effect on survival is 7–10 percentage-points (pts). The IV estimate of the IC effect on survival is 21–34 pts, and the
Bivariate Probit estimate is 17–21 pts.
We conclude that although admitted patients are at lower risk of death, as determined by their observable (to the researcher)
characteristics, controlling for observable differences, those with a higher unobserved risk of mortality are more likely
to be admitted. The implications for an optimal admission policy are discussed. 相似文献
52.
53.
Potentiation of tumor response to radiation or chemoradiation by selective cyclooxygenase-2 enzyme inhibitors 总被引:15,自引:0,他引:15
Nakata E Mason KA Hunter N Husain A Raju U Liao Z Ang KK Milas L 《International journal of radiation oncology, biology, physics》2004,58(2):369-375
Cyclooxygenase-2 (COX-2) is an enzyme expressed primarily in pathologic states, such as inflammatory disorders and cancer, where it mediates prostaglandin production. Its overexpression is associated with more aggressive biologic tumor behavior and adverse patient outcome. Increasing evidence shows that agents that selectively inhibit COX-2 enhance tumor response to radiation or chemotherapeutic agents. This article gives an overview of some of this evidence. In addition, we describe new results showing that celecoxib, a selective COX-2 inhibitor, enhanced response of A431 human tumor xenografts in nude mice to radiation by an enhancement factor (EF) of 1.43 and to the chemotherapeutic agent docetaxel by an EF of 2.07. Celecoxib also enhanced tumor response when added to the combined docetaxel plus radiation treatment (EF = 2.13). Further experiments showed that selective COX-2 inhibitors enhanced tumor cell sensitivity to ionizing radiation, involving inhibition of cellular repair from radiation damage and cell cycle redistribution as mechanisms for some cell types. The results show that selective COX-2 inhibitors have the potential to improve tumor radiotherapy or radiochemotherapy, and this therapeutic strategy is currently under clinical testing. 相似文献
54.
55.
El-Shawarby SA Ravhon A Skull J Ellenbogen A Trew G Lavery S 《Reproductive biomedicine online》2008,17(4):549-552
The aim of this study was to compare the efficacy of two embryo transfer catheters: Wallace and Rocket Embryon in an IVF programme of a tertiary referral university centre. A total of 308 patients undergoing embryo transfer were prospectively randomized to either a transfer with the Wallace catheter or a transfer with the Rocket catheter. The main outcome measure in this study was the clinical pregnancy rate, and secondary outcome measures included implantation rate, visibility of the catheter under ultrasound, number of retained embryos post transfer, and whether change of catheter was required. In addition, patient discomfort during the procedure was recorded. Pregnancy and implantation rates were similar when Wallace or Rocket catheters were used. However, for the Rocket catheter, the tip was more often clearly seen on ultrasound and it had a lower rate of retained embryos in the catheter after transfer (P < 0.05). Experience with different transfer catheters is recommended for difficult cases. 相似文献
56.
57.
Moayad Khatib Gabby Elbaz-Greener Orna Nitzan Soboh Soboh Avi Peretz Evgeni Hazanov Wadia Kinany Yusra Halahla Liza Grosman-Rimon Helene Houle Offer Amir Shemy Carasso 《Journal of digital imaging》2022,35(6):1654
Lower respiratory infection was reported as the most common fatal infectious disease. Community-acquired pneumonia (CAP) and myocardial injury are associated; yet, true prevalence of myocardial injury is probably underestimated. We assessed the rate and severity of myocardial dysfunction in patients with CAP. Admitted patients diagnosed with CAP were prospectively recruited. All the patients had C-reactive protein (CRP), brain natriuretic peptide (BNP), and high-sensitivity cardiac troponin (hs-cTnl) tests added to their routine workup. 2D/3D Doppler echocardiography was done on a Siemens Acuson SC2000 machine ≤ 24 h of diagnosis. 3D datasets were blindly analyzed for 4-chamber volumes/strains using EchobuildR 3D-Volume Analysis prototype software, v3.0 2019, Siemens-Medical Solutions. Volume/strain parameters were correlated with admission clinical and laboratory findings. The cohort included 34 patients, median age 60 years (95% CI 55–72). The cohort included 18 (53%) patients had hypertension, 9 (25%) had diabetes mellitus, 7 (21%) were smokers, 7 (21%) had previous myocardial infarction, 4 (12%) had chronic renal failure, and 1 (3%) was on hemodialysis treatment. 2D/Doppler echocardiography findings showed normal ventricular size/function (LVEF 63 ± 9%), mild LV hypertrophy (104 ± 36 g/m2), and LA enlargement (41 ± 6 mm). 3D volumes/strains suggested bi-atrial and right ventricular dysfunction (global longitudinal strain RVGLS = − 8 ± 4%). Left ventricular strain was normal (LVGLS = − 18 ± 5%) and correlated with BNP (r = 0.40, p = 0.024). The patients with LVGLS > − 17% had higher admission blood pressure and lower SaO2 (144 ± 33 vs. 121 ± 20, systolic, mmHg, p = 0.02, and 89 ± 4 vs. 94 ± 4%, p = 0.006, respectively). hs-cTnl and CRP were not different. Using novel 3D volume/strain software in CAP patients, we demonstrated diffuse global myocardial dysfunction involving several chambers. The patients with worse LV GLS had lower SaO2 and higher blood pressure at presentation. LV GLS correlated with maximal BNP level and did not correlate with inflammation or myocardial damage markers. 相似文献
58.
Soongho Park Vinay Veluvolu William S. Martin Thien Nguyen Jinho Park Dan L. Sackett Claude Boccara Amir Gandjbakhche 《Biomedical optics express》2022,13(6):3187
We present a novel method that can assay cellular viability in real-time using supervised machine learning and intracellular dynamic activity data that is acquired in a label-free, non-invasive, and non-destructive manner. Cell viability can be an indicator for cytology, treatment, and diagnosis of diseases. We applied four supervised machine learning models on the observed data and compared the results with a trypan blue assay. The cell death assay performance by the four supervised models had a balanced accuracy of 93.92 ± 0.86%. Unlike staining techniques, where criteria for determining viability of cells is unclear, cell viability assessment using machine learning could be clearly quantified. 相似文献
59.
Sk Masum Billah Tarana E. Ferdous Abu Bakkar Siddique Camille RaynesGreenow Patrick Kelly Nuzhat Choudhury Tahmeed Ahmed Stuart Gillespie John Hoddinott Rukhsana Haider Purnima Menon Shams El Arifeen Michael J. Dibley 《Maternal & child nutrition》2022,18(3)
Exclusive breastfeeding (EBF) for the first 6 months has established benefits, yet had slow improvements globally. Little is known about electronic job aid‐assisted counselling to support EBF. As a secondary outcome of a cluster randomized controlled trial in Bangladesh, we assessed the effect of electronic job aid‐supported nutrition counselling and practical demonstration on EBF. We randomized pregnant women to one of five study arms in the trial and followed mother–child dyads until 2 years of age. Community health workers (CHWs) provided breastfeeding counselling with or without prenatal and complementary nutrient supplements in all four intervention arms. The comparison arm continued with the usual practice where mothers could receive nutrition counselling at routine antenatal and postnatal care, and during careseeking for childhood illnesses. We assessed breastfeeding indicators at birth and monthly until the child was 6 months old, in both intervention and comparison arms. To evaluate the effect of nutrition counselling on breastfeeding, we combined all four intervention arms and compared them with the comparison arm. Intervention newborns had half the risk (relative risk [RR]: 0.54, 95% confidence interval [CI]: 0.39, 0.76) of receiving prelacteal feeds than those in the comparison arm. EBF declined steeply in the comparison arm after 3 months of age. EBF was 16% higher in the intervention than the comparison arm at 4 months (RR: 1.16, 95% CI: 1.08, 1.23) and 22% higher at 5 months of age (RR: 1.22, 95% CI: 1.12, 1.33). Maternal background and household characteristics did not modify the intervention effect, and we observed no difference in EBF among caesarean versus vaginal births. Breastfeeding counselling and practical demonstration using an electronic job aid by CHWs are promising interventions to improve EBF and are scalable into existing community‐based programmes. 相似文献
60.
Danilo Giffoni de Mello Morais Mata Carlos Amir Carmona Andrea Eisen Maureen Trudeau 《Current oncology (Toronto, Ont.)》2022,29(7):4956
Background: Approximately 75% of breast cancer (BC) is associated with luminal differentiation expressing endocrine receptors (ER). For ER+ HER2− tumors, adjuvant endocrine therapy (ET) is the cornerstone treatment. Although relapse events steadily continue, the ET benefits translate to dramatically lengthen life expectancy with bearable side-effects. This review of ER+ HER2− female BC outlines suitable adjuvant treatment strategies to help guide clinical decision making around appropriate therapy. Methods: A literature search was conducted in Embase, Medline, and the Cochrane Libraries, using ER+ HER−, ET BC keywords. Results: In low-risk patients: five years of ET is the standard option. While Tamoxifen remains the preferred selection for premenopausal women, AI is the choice for postmenopausal patients. In the high-risk category: ET plus/minus OFS with two years of Abemaciclib is recommended. Although extended ET for a total of ten years is an alternative, the optimal AI duration is undetermined; nevertheless an additional two to three years beyond the initial five years may be sufficient. In this postmenopausal group, bisphosphonate is endorsed. Conclusions: Classifying the risk category assists in deciding the treatment route and its optimal duration. Tailoring the breadth of ET hinges on a wide array of factors to be appraised for each individualized case, including weighing its benefits and harms. 相似文献