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   18999篇
  免费   1565篇
  国内免费   336篇
耳鼻咽喉   4104篇
儿科学   411篇
妇产科学   604篇
基础医学   1905篇
口腔科学   1999篇
临床医学   1076篇
内科学   1718篇
皮肤病学   638篇
神经病学   1118篇
特种医学   333篇
外科学   2378篇
综合类   1055篇
现状与发展   4篇
一般理论   2篇
预防医学   1720篇
眼科学   422篇
药学   637篇
  10篇
中国医学   158篇
肿瘤学   608篇
  2024年   31篇
  2023年   417篇
  2022年   442篇
  2021年   960篇
  2020年   873篇
  2019年   957篇
  2018年   871篇
  2017年   853篇
  2016年   868篇
  2015年   838篇
  2014年   1214篇
  2013年   1810篇
  2012年   910篇
  2011年   943篇
  2010年   761篇
  2009年   849篇
  2008年   812篇
  2007年   761篇
  2006年   671篇
  2005年   578篇
  2004年   512篇
  2003年   441篇
  2002年   381篇
  2001年   353篇
  2000年   322篇
  1999年   257篇
  1998年   225篇
  1997年   220篇
  1996年   185篇
  1995年   183篇
  1994年   141篇
  1993年   123篇
  1992年   131篇
  1991年   114篇
  1990年   85篇
  1989年   96篇
  1988年   89篇
  1987年   60篇
  1986年   52篇
  1985年   92篇
  1984年   77篇
  1983年   56篇
  1982年   62篇
  1981年   36篇
  1980年   43篇
  1979年   35篇
  1978年   24篇
  1977年   26篇
  1976年   23篇
  1975年   18篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
11.
BackgroundObesity in prostate cancer patients is associated with poor prostate-cancer specific outcomes. Exercise and nutrition can reduce fat mass; however, few studies have explored this as a combined pre-surgical intervention in clinical practice.PurposeThis study examined the efficacy of a weight loss program for altering body composition in prostate cancer patients prior to robot assisted radical prostatectomy (RARP).MethodsA retrospective analysis of 43 overweight and obese prostate cancer patients, aged 47–80 years, who completed a very low-calorie diet (~3000–4000 kJ) combined with moderate-intensity exercise (90 min/day) prior to RARP. Whole body and regional fat mass (FM) and lean mass (LM) were assessed by dual-energy x-ray absorptiometry pre- and post-program. Body weight, waist circumference, and blood pressure were assessed weekly, with surgery-related adverse effects recorded at time of surgery and follow-up appointments.ResultsWith a median of 29 days (IQR: 24–35days) on the program, patients significantly (p < 0.001) reduced weight (−7.3 ± 2.9 kg), FM (−5.0 ± 2.6 kg), percent body fat (−3.1 ± 2.5%), trunk FM (−3.4 ± 1.8 kg), LM (−2.4 ± 1.8 kg), and appendicular LM (−1.2 ± 1.0 kg). Lower weight, FM, percent FM, trunk FM, and visceral FM were associated with less surgery-related adverse effects (rs = 0.335 to 0.468, p < 0.010). Systolic and diastolic blood pressure were reduced (p < 0.001) by 15 ± 22 and 8 ± 10 mmHg, respectively over the weight loss intervention.ConclusionUndertaking a combined low-calorie diet and exercise program for weight loss in preparation for RARP resulted in substantial reductions in FM, with improvements in blood pressure, that may benefit surgical outcomes.  相似文献   
12.
Accurate ionization chamber measurements of the absorbed dose to water require the correction of incomplete collection of charges created within the chamber volume. According to current dosimetry protocols such as the TRS-398 or the DIN 6800-2, incomplete charge collection is accounted for by the correction factor ks, which can be determined numerically or experimentally. The method proposed by Burns & McEwen (Phys. Med. Biol., 1998) was used in this study to determine the coefficients γ and δ used for the calculation of the correction factor ks of three ionization chambers, the SNC 125c, the SNC 600c and the SNC 350p (all Sun Nuclear Corp., Melbourne, Florida) for an absorbed dose to water range of 0.2 mGy to 1.6 mGy per pulse in pulsed photon beams. The shift of the effective point of measurement from the reference point Δz and the correction factor kr were determined for the SNC 350p according to the draft DIN 6800-2:2019-07.  相似文献   
13.
14.
15.
16.

Objective

Successful weight loss interventions for African-Americans adolescents are lacking. Cognitive-behavioral interventions seek to develop weight loss skills (e.g., counting calories, goal setting, managing one's environment). Little is known about how well adolescents implement such skills in their daily lives. Study aims were to (1) examine weight loss skills utilization at midpoint and end of a 6-month cognitive-behavioral/motivational interviewing weight loss sequential multiple assignment randomized trial (SMART), and (2) determine if greater skill utilization predicted weight loss at treatment end and 3 months post-treatment.

Method

One hundred and eighty six African-Americans adolescents with obesity and their caregiver were first randomly assigned to complete 3 months of cognitive-behavioral and motivational interviewing family-based weight loss treatment in their home or in the research office (Phase 1). Nonresponders (i.e., those who lost < 3% of initial weight, n?=?161) were rerandomized to 3 months of continued skills training (n?=?83) or contingency management (n?=?78) for Phase 2; responders were allocated to 3 months of relapse prevention (n?=?20). Adolescents’ frequency of weight loss skills utilization was assessed via questionnaire at treatment midpoint and end.

Results

Higher treatment attendance was associated with better skill utilization. Higher skill utilization was associated with more weight loss at treatment end, whereas higher baseline confidence was associated with more weight loss at follow-up.

Conclusions

This study indicates the importance of attending weight loss intervention sessions to develop and strengthen weight loss skills in African-American adolescents with obesity, and strengthening confidence to use such skills for continued weight loss.  相似文献   
17.
ObjectivesThis document presents the fundamentals of speech audiometry in noise, general requirements for implementation and criteria for choice among the tests available in French according to the health-professional's needs.Material and methodsThe recommendations are based on a systematic analysis of the literature carried out by a multidisciplinary group of doctors, audiologists and audioprosthetists from all over France. They are graded A, B, C or expert opinion according to decreasing level of scientific evidence.ResultsEight tests of speech audiometry in noise can be used in France.ConclusionTo be complete, evaluation of hearing status requires testing understanding of speech in noise. The examination must begin with a minimum of two measurements familiarizing the subject with the test procedure. For initial diagnosis, adaptive procedures establishing the 50% speech reception threshold (SRT50) in noise are to be preferred in order to obtain a rapid and standardized measurement of perception of speech in noise. When the aim is to measure real-life speech comprehension, tests based on sentences, cocktail-party noise and free-field stimulation are to be preferred. Prosthetic gain is evaluated exclusively in free field. This is the only way to evaluate the contribution of binaurality and to measure perception in noise in an environment as close as possible to real life. In order to avoid acoustic interference in free field, at least five loudspeakers should be used, in particular for evaluating the effectiveness of directional microphones, CROS devices enabling sounds picked up in the damaged ear to be rerouted to the functional ear, or bimodal fitting (i.e., when hearing is enabled by two modalities: for example, hearing aid for one ear, cochlear implant for the other).  相似文献   
18.
19.
ABSTRACT

A qualitative grounded theory approach was used to analyze 34 narratives from young men about their experience of retaining, losing, or giving away their virginity, where 7 said they were virgins, 26 said they were non-virgins, and one did not mention his virginity status. We found that virginity is a multidimensional concept, with two distinct dimensions: the experiential and the developmental. The experiential dimension refers to young men's perception and understanding of their virginity in four overlapping areas: physical, spiritual, relational, and emotional. The developmental dimension refers to young men's perception of their underlying sexual identity growth processes and the gendered and sexual double standards that influence this understanding. Clinical implications of this study are useful in education and counseling. They seek to empower young men with information relating to the multidimensional nature of virginity experience, and minimize the negative effects on romantic relationships, sexual adjustment, and self-identity development. The findings are helpful in designing interventions for young men and women who are at high risk for sexually transmitted infections and can help them negotiate mutually safe and pleasurable experiences regarding their virginity.  相似文献   
20.
BackgroundScarce data exists regarding United States (US) national-level work productivity loss among adults with Multiple Sclerosis (MS).ObjectiveTo address this significant knowledge gap, we examined the national-level productivity loss among adults (18≤ age ≤64 years) with MS compared to propensity score matched non-MS controls.MethodsWe adopted a retrospective, cross-sectional, matched cohort study design with pooled data from alternate years (2005/2007/2009/2011/2013/2015) of the Medical Expenditure Panel Survey (MEPS). We included adults who were employed and alive during the calendar year. Clinical Classification System code of “80” was used to identify individuals with MS. We matched adults with MS to non-MS adults utilizing propensity scores generated based on age, gender, and race/ethnicity using a greedy matching algorithm (8:1-digit matching). Missed workdays measured productivity loss of MEPS respondents. We selected Negative Binomial Regression (NBR) analysis as the count data model for this study. Analyses were conducted using SAS 9.4 and STATA 15.0 and accounted for the complex survey design of MEPS to generate US national-level estimates.ResultsThe final propensity-score matched sample consisted of 104 and 312 (unweighted) adults with and without MS, respectively. US national-level mean [Standard Error (SE)] annual missed workdays among individuals with MS [8.94 (SE:1.59)] was significantly higher (p = 0.001) compared to propensity score matched non-MS controls [3.15 (SE:0.40)]. After adjusting for several factors, NBR showed an approximately two-fold higher rate of missed work days among individuals with MS compared to propensity score matched non-MS controls (Incidence Rate Ratio: 1.98, 95% Confidence Interval: 1.18–3.33). Severity of pain, marital status, region, and hypertension also negatively impacted work productivity in this sample.ConclusionsIndividuals with MS in the US experience significantly higher productivity loss compared to propensity score matched non-MS controls. Interventions (e.g., improved management of MS symptoms) are warranted to reduce productivity loss among individuals with MS.  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