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   92799篇
  免费   3834篇
  国内免费   3702篇
耳鼻咽喉   478篇
儿科学   1912篇
妇产科学   2166篇
基础医学   7232篇
口腔科学   2486篇
临床医学   9350篇
内科学   12756篇
皮肤病学   676篇
神经病学   2454篇
特种医学   4631篇
外国民族医学   2篇
外科学   6322篇
综合类   18679篇
一般理论   13篇
预防医学   11977篇
眼科学   2077篇
药学   6948篇
  5篇
中国医学   5980篇
肿瘤学   4191篇
  2023年   259篇
  2022年   411篇
  2021年   511篇
  2020年   455篇
  2019年   364篇
  2018年   521篇
  2017年   444篇
  2016年   533篇
  2015年   622篇
  2014年   906篇
  2013年   1353篇
  2012年   2066篇
  2011年   6560篇
  2010年   3773篇
  2009年   2513篇
  2008年   3113篇
  2007年   2840篇
  2006年   3037篇
  2005年   4269篇
  2004年   10519篇
  2003年   9569篇
  2002年   7546篇
  2001年   5888篇
  2000年   3685篇
  1999年   4241篇
  1998年   2925篇
  1997年   2621篇
  1996年   1709篇
  1995年   1492篇
  1994年   1504篇
  1993年   2333篇
  1992年   1971篇
  1991年   1672篇
  1990年   1320篇
  1989年   1124篇
  1988年   876篇
  1987年   780篇
  1986年   749篇
  1985年   456篇
  1984年   287篇
  1983年   222篇
  1982年   155篇
  1981年   137篇
  1979年   172篇
  1978年   128篇
  1977年   126篇
  1976年   115篇
  1975年   118篇
  1974年   117篇
  1973年   128篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
SUMMARY BACKGROUND DATA: Previous studies have suggested a variety of factors that may affect the false negative (FN) rate for sentinel lymph node (SLN) biopsy in breast cancer. Because FN results are relatively rare, no prior studies have had sufficient sample size to allow detailed statistical analysis of factors predicting FN results. METHODS: Patients with clinical stage T1-2, N0 invasive breast cancer were enrolled in a prospective, multicenter study. All patients underwent SLN biopsy, followed by planned completion axillary dissection regardless of the SLN results, to assess the FN rate. SLN biopsy was performed using radioactive colloid injection in combination with isosulfan blue dye in 94% of cases. Dermal, subdermal, peritumoral, or subareolar radioactive colloid injection techniques were used at the discretion of each institution. Univariate and multivariate analyses were performed to identify factors associated with a FN result. RESULTS: SLNs were identified in 3870 of 4117 patients (94%). There were 1243 true positive, 2521 true negative, and 106 FN results. Age, histologic subtype, the number of non-SLN removed, tumor palpability, type of breast biopsy, and SLN injection technique were not significant factors. On multivariate analysis, tumor size <2.5 cm, upper outer quadrant tumor location, removal of only a single SLN, minimal surgeon experience, presence of a single positive axillary LN, and use of immunohistochemistry (IHC) for SLN analysis were independently associated with an increased risk of FN results. CONCLUSIONS: Surgeon experience, tumor size and location, and the number of SLN removed are preoperative and intraoperative factors that independently predict the risk of a FN result. In contrast to suggestions from other smaller studies, age does not affect the likelihood of a FN result; a lesser, rather than greater, number of positive axillary nodes was associated with an increased likelihood of a FN result; and IHC analysis of the SLN increases, rather than decreases, the risk of FN results.  相似文献   
992.
PURPOSE: We determined retrospectively in a population based study the survival of patients with bladder cancer and the local recurrence rate (LRR) after cystectomy. MATERIALS AND METHODS: All patients with bladder cancer diagnosed between 1988 and 2001 (vital status updated until September 2003) were selected from the Amsterdam Cancer Registry, which covers a population of 2.84 million individuals. For all patients who underwent cystectomy between 1988 and 1997 at 18 participating hospitals information on local recurrence and vital status was collected from the medical records. RESULTS: Five-year relative survival in all 8,321 bladder cancer cases combined was 75%. For clinical stage 0-a this was 99%, decreasing to 85% for stage 0-is and 82% for stage I, and to 44%, 28% and 9% for stages II to IV, respectively. Five-year relative survival after cystectomy was 81%, 44% and 23% for stages II to IV, respectively. The LRR after cystectomy was 19% in all 566 cases and all institutions combined. The LRR increased with higher pT stage and it achieved 11%, 23% and 31% for stages II to IV, respectively. It was slightly lower at oncological centers than at community hospitals (18% vs 20%, not significant). CONCLUSIONS: Survival is higher than the European average but below the value in the United States. Only 1 of 3 stages II-III cases was treated with cystectomy. Relatively high stage specific survival is experienced after cystectomy despite local recurrence in 1 of 5 patients.  相似文献   
993.
BACKGROUND AND OBJECTIVE: Gold nanoshells are a new class of nanoparticles that can be designed to strongly absorb light in the near infrared (NIR). These particles provide much larger absorption cross-sections and efficiency than can be achieved with currently used chemical chromophores without photobleaching. In these studies, we have investigated the use of gold nanoshells as exogenous NIR absorbers to facilitate NIR laser-tissue welding. STUDY DESIGN/MATERIALS AND METHODS: Gold nanoshells with peak extinction matching the NIR wavelength of the laser being used were manufactured and suspended in an albumin solder. Optimization work was performed on ex vivo muscle samples and then translated into testing in an in vivo rat skin wound-healing model. Mechanical testing of the muscle samples was immediately performed and compared to intact tissue mechanical properties. In the in vivo study, full thickness incisions in the dorsal skin of rats were welded, and samples of skin were excised at 0, 5, 10, 21, and 32 days for analysis of strength and wound healing response. RESULTS: Mechanical testing of nanoshell-solder welds in muscle revealed successful fusion of tissues with tensile strengths of the weld site equal to the uncut tissue. No welding was accomplished with this light source when using solder formulations without nanoshells. Mechanical testing of the skin wounds showed sufficient strength for closure and strength increased over time. Histological examination showed good wound-healing response in the soldered skin. CONCLUSIONS: The use of nanoshells as an exogenous absorber allows the usage of light sources that are minimally absorbed by tissue components, thereby, minimizing damage to surrounding tissue and allowing welding of thicker tissues.  相似文献   
994.
995.
To examine the degree of trauma in major osteoporotic fractures (MOF) in men versus women, we used data from 15,698 adults aged ≥65 years enrolled in the Osteoporotic Fractures in Men (MrOS) study (5994 men) and the Study of Osteoporotic Fractures (SOF) (9704 women). Participants were contacted tri‐annually to ascertain incident fractures, which were confirmed by radiographic reports and coded according to degree of self‐reported trauma. Trauma was classified as low (fall from ≤ standing height; fall on stairs, steps, or curb; minimal trauma other than fall [coughing, turning over]); moderate (collisions with objects during normal activity without associated fall); or high (fall from > standing height; severe trauma [motor vehicle accident, assault]). MOF included hip, clinical vertebral, wrist, and humerus fractures. Mean fracture follow‐up was 9.1 years in SOF and 8.7 years in MrOS. A total of 14.6% of the MOF in men versus 6.3% of the MOF in women were classified as high trauma (p < 0.001); men versus women more often experienced fractures resulting from severe trauma as well as from fall > standing height. High‐trauma fractures were more significantly common in men versus women at the hip (p = 0.002) and wrist (p < 0.001) but not at the spine or humerus. Among participants with MOF, the odds ratio of a fracture related to high‐trauma fracture among men versus women was 3.12 (95% confidence interval [CI] 1.70–5.71) after adjustment for traditional risk factors. Findings were similar in analyses limited to participants with hip fractures (odds ratio [OR] = 3.34, 95% CI 1.04–10.67) and those with wrist fracture (OR = 5.68, 95% CI 2.03–15.85). Among community‐dwelling older adults, MOF are more likely to be related to high trauma in men than in women. These findings are not explained by sex differences in conventional risk factors and may reflect a greater propensity among men to engage in risky behavior. © 2015 American Society for Bone and Mineral Research.  相似文献   
996.
Objective  Restorative proctocolectomy (RPC) with ileal pouch-anal anastomosis (IPAA) is well-established in the management of ulcerative colitis (UC) and familial adenomatous polyposis (FAP). We review outcome of pouch surgery from a single centre, comparing non-South Asian and South Asian Caucasian populations.
Method  Patients undergoing RPC for UC and FAP during a 10-year period between January 1997 and January 2007 were identified from hospital records. Data were collected retrospectively from case notes on early and long-term results.
Results  A total of 107 patients underwent pouch formation for UC (94%) or FAP (6%) and 22 (21%) were from the Asian subcontinent. Eighty-seven (81%) underwent a three-stage procedure and 20 (19%) a two-stage procedure. Postoperative complications occurred in 40 (37%) patients, being major in 11 (10%) patients with relaparotomy required in 9 (8%) with no difference between South Asian and non-South Asian Caucasian patients. Long-term pouch function, with a median of five times over 24 h (range 2–15), was similar between the two groups. The incidence of pouchitis was 57 (53%) and this was significantly greater in the South Asian population [17/21 (77%); 39/86 (46%); P  = 0.006].
Conclusion  Surgical results were similar in South Asian and non-South Asian Caucasian patients, but the incidence of pouchitis was greater in the former group.  相似文献   
997.
Objective:   To characterize the clinical outcome in a large contemporary series of Japanese patients with newly diagnosed Ta, T1 non-muscle invasive bladder cancer who underwent transurethral bladder tumor resection with or without intravesical chemotherapy or Bacillus Calmette-Guérin (BCG) therapy.
Methods:   We developed a database incorporating newly diagnosed non-muscle invasive bladder cancer data and outcomes from a Japanese bladder cancer registry between 1999 and 2001 and identified a study population of 3237 consecutive patients who had complete data based on pathological features. Median patient age was 69.9 years.
Results:   The 1-year, 3-year, and 5-year overall recurrence-free survival rates were 77.0%, 61.3%, and 52.8%, respectively. In multivariate analyses, the multiplicity of bladder tumors, tumor size greater than 3 cm, pathological stage T1, tumor grade G3, and the absence of adjuvant intravesical instillation were independent risk factors for tumor recurrence. Overall, 1710 patients (52.8%) received intravesical instillation; chemotherapy in 1314 (76.8%) and BCG treatment in 396 (23.2%). In patients treated with intravesical chemotherapy in which an anthracycline chemo-agent was used in 90.5% of the cases, multivariate analyses demonstrated that male gender, multiple bladder tumors, a tumor size greater than 3 cm, and pathological stage T1 were associated with tumor recurrence.
Conclusions:   The accumulation and analysis of data from the Japanese National Bladder Cancer Registry made it possible to determine the clinical characteristics, management trends, and survival rates for the period studied. Further study with a dataset created from longer follow-up data would be warranted to analyze tumor progression and disease survival.  相似文献   
998.

Editorial

Focus on Disaster Medicine Introduction to the second “Focus-on” Disaster and Military Surgery  相似文献   
999.
目的:观察高糖环境下人近端肾小管上皮细胞HK-2中p66Shc的表达和磷酸化,以及p66Shc瞬时高表达对高糖诱导的HK-2线粒体活性氧簇产生的影响,为探讨糖尿病肾病线粒体ROS产生的机制提供新的思路。方法:常规培养正常人近端肾小管上皮细胞(HK-2),将30mmol/LD-葡萄糖在不同时间点作用于体外培养的HK-2细胞,采用Real—time—PCR检测p66ShcmRNA的表达变化,Western blot检测p66Shc蛋白、磷酸化p66Shc—Ser36蛋白的表达;进一步将pcDNA3.1hisp66Shc质粒转染HK-2细胞,采用激光共聚焦显微镜观察p66Shc高表达对高糖诱导的线粒体活性氧簇产生的影响。结果:30mmol/LD-葡萄糖能呈时间依赖性上调p66ShcmRNA和蛋白表达水平,同时增强p66Shc第36位丝氨酸的磷酸化;在30mmol/LD-葡萄糖作用下,转染p66Shc的HK-2线粒体ROS水平明显高于未转染组及空载体转染组(P〈0.05)。结论:p66Shc参与了高糖诱导的线粒体活性氧簇的产生,可能在糖尿病肾病早期肾小管氧化损伤过程中发挥重要作用。  相似文献   
1000.
排斥反应是影响移植肾长期存活的首要独立危险因素,是亟待解决的瓶颈问题。中华医学会器官移植学分会和中国医师协会器官移植医师分会组织国内专家,总结各中心肾移植的临床经验,依据Banff 2013标准,编写了本部指南,希望能为相关临床科室提供工作指引。  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