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   2253篇
  免费   209篇
  国内免费   28篇
耳鼻咽喉   7篇
儿科学   88篇
妇产科学   119篇
基础医学   262篇
口腔科学   19篇
临床医学   186篇
内科学   368篇
皮肤病学   12篇
神经病学   226篇
特种医学   128篇
外科学   449篇
综合类   38篇
预防医学   191篇
眼科学   22篇
药学   211篇
肿瘤学   164篇
  2022年   16篇
  2021年   20篇
  2020年   14篇
  2018年   25篇
  2017年   25篇
  2016年   21篇
  2015年   24篇
  2014年   43篇
  2013年   81篇
  2012年   82篇
  2011年   101篇
  2010年   80篇
  2009年   55篇
  2008年   77篇
  2007年   92篇
  2006年   73篇
  2005年   82篇
  2004年   70篇
  2003年   60篇
  2002年   74篇
  2001年   74篇
  2000年   82篇
  1999年   77篇
  1998年   46篇
  1997年   39篇
  1996年   37篇
  1995年   37篇
  1994年   26篇
  1993年   30篇
  1992年   59篇
  1991年   72篇
  1990年   65篇
  1989年   66篇
  1988年   81篇
  1987年   67篇
  1986年   73篇
  1985年   62篇
  1984年   37篇
  1983年   25篇
  1982年   21篇
  1981年   21篇
  1980年   21篇
  1979年   25篇
  1978年   21篇
  1977年   29篇
  1976年   25篇
  1975年   16篇
  1974年   28篇
  1973年   13篇
  1969年   14篇
排序方式: 共有2490条查询结果,搜索用时 15 毫秒
41.
42.
OBJECTIVES: To determine the spectrum of N and G genotypes of respiratory syncytial virus (RSV) causing respiratory tract infection and whether particular genotypes are associated with severity of infection. PATIENTS AND METHODS: Nasopharyngeal aspirates (NPAs) were obtained from 114 infants with acute respiratory tract infection due to RSV over two seasons. Viral mRNA was extracted from NPAs or cultured virus, reverse transcribed, and the cDNA amplified by the polymerase chain reaction using primers directed to parts of the N and G gene respectively. Amplicons were separately digested with four different restriction endonucleases for each gene. The fragments were separated by agarose gel, electrophoresis, and the electrophoretic patterns used to assign the various genotypes. Disease severity was assessed as very mild (upper respiratory tract signs only), mild (coryza and signs of lower respiratory tract infection), moderate (requiring nasogastric or intravenous fluids), and severe (requiring oxygen or ventilation). RESULTS: Five of the six known N genotypes were detected, but NP4 and NP2 were found most frequently. There was no association between N genotype and disease severity. Six G (SHL) genotypes were detected. Significantly (p = 0.04) more of the infants infected with the SHL2 genotype had severe or moderate disease. CONCLUSIONS: During the seasonal peaks of RSV respiratory tract infection at least 10 different RSV genotypes cocirculated. While there is no association between N genotypes and disease severity, infection with the SHL2 G genotype appears to result in moderate to severe disease.  相似文献   
43.
BACKGROUND: The purpose of this study was to examine the effects of a steam burn injury on apoptosis in gut-associated lymphoid tissue and to determine whether endogenous glucocorticoid and Fas ligand signaling were involved in this process. METHODS: Histologic analysis, in situ deoxynucleotidyl transferase dUTP nick-end labeling staining and annexin V and 7-amino-actinomycin-D flow cytometry of lymphocyte populations were evaluated in intraepithelial lymphocytes and Peyer's patch. Additional mice were pretreated with a glucocorticoid receptor antagonist (mifepristone) before the steam burn. Similarly, C3H/HeJ-FasL(gld) mice lacking functional Fas ligand were also studied. RESULTS: Apoptosis was significantly increased in intraepithelial lymphocytes and Peyer's patch after the burn injury. Mifepristone pretreatment significantly reduced apoptosis in both T- and B-cell populations in intraepithelial lymphocytes after the burn injury. In contrast, the increased apoptosis seen in B-cells from Peyer's patch was not seen in C3H/HeJFasL(gld) mice, whereas the increased apoptosis in CD8+ T-cells was unaffected. CONCLUSION: Both corticosteroids and FasL contribute to the apoptosis in gut-associated lymphoid tissues early after burn injury.  相似文献   
44.
45.
An uncontrolled study with process evaluation was conducted in three U.K. community maternity sites to establish the feasibility and acceptability of delivering a novel breastfeeding peer‐support intervention informed by motivational interviewing (MI; Mam‐Kind). Peer‐supporters were trained to deliver the Mam‐Kind intervention that provided intensive one‐to‐one peer‐support, including (a) antenatal contact, (b) face‐to‐face contact within 48 hr of birth, (c) proactive (peer‐supporter led) alternate day contact for 2 weeks after birth, and (d) mother‐led contact for a further 6 weeks. Peer‐supporters completed structured diaries and audio‐recorded face‐to‐face sessions with mothers. Semistructured interviews were conducted with a purposive sample of mothers, health professionals, and all peer‐supporters. Interview data were analysed thematically to assess intervention acceptability. Audio‐recorded peer‐support sessions were assessed for intervention fidelity and the use of MI techniques, using the MITI 4.2 tool. Eight peer‐supporters delivered the Mam‐Kind intervention to 70 mothers in three National Health Service maternity services. Qualitative interviews with mothers (n = 28), peer‐supporters (n = 8), and health professionals (n = 12) indicated that the intervention was acceptable, and health professionals felt it could be integrated with existing services. There was high fidelity to intervention content; 93% of intervention objectives were met during sessions. However, peer‐supporters reported difficulties in adapting from an expert‐by‐experience role to a collaborative role. We have established the feasibility and acceptability of providing breastfeeding peer‐support using a MI‐informed approach. Refinement of the intervention is needed to further develop peer‐supporters' skills in providing mother‐centred support. The refined intervention should be tested for effectiveness in a randomised controlled trial.  相似文献   
46.
ObjectiveTo describe the response rate (RR), progression-free survival (PFS), and toxicity profile of combination gemcitabine, platinum, and bevacizumab (GPB) for the treatment of recurrent epithelial ovarian cancer (EOC).MethodsA chart review of all patients with recurrent EOC who were treated with D1, D15 GPB in a 28-day cycle at a single institution was performed. Standard doses were gemcitabine 1000 mg/m2, cisplatin 30 mg/m2 or carboplatin AUC 3, and bevacizumab 10 mg/kg. All patients were analyzed for toxicity. RR and PFS were assessed in all patients who received at least 2 cycles of GPB.ResultsThirty-five patients were identified, and 33 received at least 2 cycles of GPB. The majority of patients (80%) were platinum sensitive. Patients received a median of 6 cycles of GPB (range 1–24). Sixteen patients (48%) had a complete response (CR), and 10 patients (30%) had a partial response (PR), for a total RR of 78%. An additional 5 patients (15%) had stable disease, and only 2 (6%) patients had progressive disease. The median overall PFS was 12 months (95% CI 7–15), with a median follow-up time of 10 months (2–22). Two patients (6%) had bowel perforations, and both survived. Hematologic toxicities were most common, with 29% and 14% of patients experiencing grade 3 or 4 neutropenia and thrombocytopenia respectively.ConclusionsThe combination of GPB demonstrated excellent efficacy for the treatment of recurrent EOC. However, serious toxicities occurred, and the safety profile of this combination requires further study.  相似文献   
47.
48.
Dr. Copeland describes the development of The American Joint Committee on Cancer Staging and End Results Reporting, its objectives, and the steps in the preparation of the clinical classifications. Emphasis is on simplicity, practicability and credibility. The TNM (tumor, nodes, metastasis) system is utilized where possible.  相似文献   
49.
A review of literature concerning familial violence and mental illness using the Vulnerable Populations Conceptual Model (VPCM) as an organizing framework is presented. Since family members are most likely to be targets if a person who is mentally ill becomes violent, this review emphasizes the VPCM concepts of resource availability (including capital, stigma, and access to healthcare), risk, and health status of those family members. The population-based VPCM was used in an attempt to move the examination of this phenomenon from a focus on the individual to a conceptualization of it as family violence occurring within a broader, social context.  相似文献   
50.
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