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   12952篇
  免费   640篇
  国内免费   77篇
耳鼻咽喉   74篇
儿科学   264篇
妇产科学   330篇
基础医学   1752篇
口腔科学   479篇
临床医学   1086篇
内科学   3647篇
皮肤病学   328篇
神经病学   1262篇
特种医学   317篇
外科学   1669篇
综合类   60篇
一般理论   2篇
预防医学   678篇
眼科学   189篇
药学   672篇
中国医学   35篇
肿瘤学   825篇
  2023年   97篇
  2022年   207篇
  2021年   439篇
  2020年   221篇
  2019年   292篇
  2018年   428篇
  2017年   261篇
  2016年   336篇
  2015年   344篇
  2014年   505篇
  2013年   637篇
  2012年   1054篇
  2011年   1061篇
  2010年   591篇
  2009年   586篇
  2008年   941篇
  2007年   935篇
  2006年   872篇
  2005年   768篇
  2004年   693篇
  2003年   612篇
  2002年   625篇
  2001年   65篇
  2000年   59篇
  1999年   86篇
  1998年   102篇
  1997年   103篇
  1996年   87篇
  1995年   70篇
  1994年   72篇
  1993年   61篇
  1992年   40篇
  1991年   41篇
  1990年   37篇
  1989年   33篇
  1988年   27篇
  1987年   20篇
  1986年   23篇
  1985年   13篇
  1984年   32篇
  1983年   28篇
  1982年   21篇
  1981年   22篇
  1980年   17篇
  1979年   9篇
  1978年   11篇
  1977年   18篇
  1974年   11篇
  1973年   7篇
  1972年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
OBJECTIVE: Despite multiple and repeated exposures to HIV-1, some individuals possess no detectable HIV genome and show T-cell memory responses to the viral antigens. HIV-1-reactive mucosal IgA detected in such uninfected individuals suggests their possible immune resistance against HIV. We tested if the above HIV-1-exposed but uninfected status was associated with genetic markers other than a homozygous deletion of the CCR5 gene. METHODS: Based on our mapping in chromosome 15 of a gene controlling the production of neutralizing antibodies in a mouse retrovirus infection, we genotyped 42 HIV-1-exposed but uninfected Italians at polymorphic loci in the syntenic segment of human chromosome 22, and compared them with 49 HIV-1-infected and 47 uninfected healthy control individuals by a closed testing procedure. RESULTS: A significant association was found between chromosome 22q12-13 genotypes and a putative dominant locus conferring anti-HIV-1 immune responses in the exposed but uninfected individuals. Distributions of linkage disequilibrium across chromosome 22 also differed between the exposed but uninfected and two other phenotypic groups. CONCLUSIONS: The data indicated the presence of a new genetic factor associated with the HIV-1-exposed but uninfected status.  相似文献   
102.
Summary The authors studied the relationship between age, year of onset of the disease and sex in 1,428 diabetic subjects. The whole population of the province of La Spezia was used for comparison. As for the M/F ratio, differences of homogeneousness were not observed between the diabetics examined and the population of the province. When the series was subdivided according to the year in which diabetes was diagnosed, it was found that from the five-year period 1950–1954 to the five-year period 1965–1969 the M/F ratio had changed from 0.47 to 0.96. Statistically, this is equivalent to an exponential function.  相似文献   
103.
Introduction: Patients with schizophrenia or bipolar disorder treated with antipsychotic medication can frequently experience lack of efficacy and persistent side-effects, so much so that switching from one antipsychotic to another with a different side-effect profile has become a recommended strategy for improving the tolerability and safety of long-term antipsychotic treatment. Aripiprazole is an atypical antipsychotic with proven efficacy in schizophrenia and bipolar I disorder, with a pharmacological profile distinct from other available antipsychotics and a side-effect profile that is different from other agents in the class; these characteristics make it a possible alternative in patients requiring a change in antipsychotic treatment due to lack of efficacy or persistent side-effects.

Areas covered: A panel of Italian experts in psychiatry met to discuss the appropriateness of current strategies for the switch to aripiprazole in patients with schizophrenia or bipolar disorder once a clinician has decided to adopt this choice and also to propose alternate strategies where required. The strategies for the switch to aripiprazole presented in this position paper consider various scenarios encountered in clinical practice, highlight the importance of tapering the prior antipsychotic based on its pharmacological characteristics and provide detailed guidance throughout the entire switching process. Literature searches were conducted using the PubMed database and the search strategy (aripiprazole and switching); additional references were added from the reference lists of the papers obtained and also from the authors’ knowledge of the topic.

Expert opinion: Few studies have addressed the indications for antipsychotic switching and the best practical strategies to achieve the desired goal in the clinical practice setting. Studies on antipsychotic switching should clarify why, when and how a switch should be done. The results should standardize the reasons for switching an antipsychotic, assess the optimal time to switch and evaluate the best ways to switch. Both clinical and pharmacological factors should be considered when a patient needs to switch antipsychotics, and specific guidelines for antipsychotic switching that address all these factors are needed.  相似文献   

104.
105.
Laparoscopic resections for colorectal carcinoma   总被引:6,自引:3,他引:6  
Laparoscopic resection for carcinoma of the colon and rectum is currently under intense scrutiny. PURPOSE: The purpose of this study is to review our three-year experience of laparoscopic surgery for colon and rectal carcinoma. METHODS: From October 1991 to September 1994, 76 laparoscopic procedures were performed for colorectal neoplasia (32 males and 44 females; mean age, 69 years). Fifty-five procedures were done for carcinoma, 16 for large polyps, and five for diversion in patients with unresectable cancer. For resectable tumors, the average size was 4 cm; staging was as follows: Dukes A, 10 patients; Dukes B1, 11; Dukes B2, 18; Dukes C1, 1; Dukes C2, 9; and Dukes D, 8. Fourteen cases (25 percent) that were converted to open procedures were compared with the 41 cases that were completed laparoscopically for differences in tumor size, surgical margins, number of lymph nodes harvested, length of hospital stay, and evidence of recurrence. Procedures completed laparoscopically were then compared with a group of open controls completed during the same time period. RESULTS: During the first six months, the conversion rate was 32 percent but dropped to 8 percent in the last six months. There were a total of 19 complications (25 percent), of which 8 (14 percent) were directly related to the laparoscopic technique. The mean number of lymph nodes harvested in laparoscopic resection for carcinoma was 8.5, and the average closest tumor margin was 4.5 cm. When laparoscopic resections were compared with converted and standard open colectomies, there was no significant difference in tumor margins or numbers of nodes resected. Length of stay was significantly shorter for anterior resections completed laparoscopically than for converted or conventional colectomies. Although this was also the trend for right hemicolectomies, it did not reach statistical significance. Mean follow-up of the group completed laparoscopically was 16.7 months, during which there was one recurrence. There were no trocar site recurrences. CONCLUSIONS: This early experience seems to indicate that laparoscopic surgery for colorectal carcinoma does not per se compromise surgical oncologic principles and encourages us to continue our critical appraisal of this technique.Read at the meeting of The American Society of Colon and Rectal Surgeons, Montreal, Quebec, Canada, May 7 to 12, 1995.  相似文献   
106.
The possibility that isosorbide dinitrate (ISDN) inhibits platelet function in humans has been explored in vitro and in vivo. Incubation of citrated plateletrich plasma from healthy subjects with scalar concentrations (1.25, 12.5 and 125 μg/ml) of ISDN for 5 and 10 minutes resulted in a decrease in platelet aggregation after ADP, adrenaline, and arachidonic acid at the highest drug concentration (mean decrease: 72% [p < 0.01], 56% [p < 0.05] and 62% [p < 0.05], respectively, with the 10-minute incubation). Also, a significant reduction (30%) in generated thromboxane (TX)B2 levels was observed after arachidonic acid (p < 0.01). ISDN was then infused at rate of 4 mg/hour for 30 minutes in 11 patients with angina and at a rate of 30 mg/hour for 20 minutes in 8. The smaller dose, which caused minor changes in arterial pressure and heart rate, was accompanied by a marked, significant decrease in ADP- and adrenaline-induced aggregation, with a nadir at 60 minutes from the infusion stop (decreases of 40% and 51% respectively). Circulating platelet aggregates also decreased, with a minimum (? 41%, p < 0.05) at the end of the infusion. The higher infusion rate, causing marked hemodynamic effects, was not accompanied by the occurrence of clear antiplatelet effects. Thus, ISDN can affect platelet function both in vitro and in vivo. The in vivo effect occurs at lower concentrations than in vitro but is blunted when a marked hemodynamic response occurs.  相似文献   
107.
Injectable bone fillers represent an attractive strategy for the treatment of bone defects. These injectable materials should be biocompatible, capable of supporting cell growth and possibly able to exert antibacterial effects. In this work, nanocomposite microbeads based on alginate, chitlac, hydroxyapatite and silver nanoparticles were prepared and characterized. The dried microbeads displayed a rapid swelling in contact with simulated body fluid and maintained their integrity for more than 30 days. The evaluation of silver leakage from the microbeads showed that the antibacterial metal is slowly released in saline solution, with less than 6% of silver released after 1 week. Antibacterial tests proved that the microbeads displayed bactericidal effects toward Staphylococcus aureus, Pseudomonas aeruginosa and Staphylococcus epidermidis, and were also able to damage pre‐formed bacterial biofilms. On the other hand, the microbeads did not exert any cytotoxic effect towards osteoblast‐like cells. After characterization of the microbeads bioactivity, a possible means to embed them in a fluid medium was explored in order to obtain an injectable paste. Upon suspension of the particles in alginate solution or alginate/hyaluronic acid mixtures, a homogenous and time‐stable paste was obtained. Mechanical tests enabled to quantify the extrusion forces from surgical syringes, pointing out the proper injectability of the material. This novel antibacterial bone filler appears as a promising material for the treatment of bone defects, in particular when possible infections could compromise the bone‐healing process. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
108.
109.
Despite all the emphasis laid today on the green economy, occupational health and safety (OHS) issues have still been talked only limitedly, as already noted in previous studies and literature reviews. The Department of Occupational and Environmental Medicine, Epidemiology and Hygiene of the Italian Workers’ Compensation Authority (INAIL) has conducted a survey among some Italian stakeholders, social partners, institutions and “green” businesses to gather their perceptions of the potential effects of green jobs on OHS, particularly in the renewable energy sector. The survey involved a sample of 61 stakeholders in the following categories: institutions (11), trade unions (11), employers’ organizations (13), businesses (11), research (15). Participation in this survey of national stakeholders who have a central role in the development and management of policies on renewable energy and OHS, allowed to analyze in depth the fundamental aspects for a fair transition towards green economy. Also, the good agreement among respondents brought to light quite clearly the main critical points as regards the OHS implications of green work in Italy, and pointed to the principal policies to be adopted to safeguard workers’ health and safety.  相似文献   
110.
We report a case of a secundipara with heterotopic cesarean scar pregnancy (HCSP) treated with potassium chloride injection into the ectopic embryo followed by sac aspiration. The remaining “mass” increased in size threefold and was surrounded by a rich vascular network. An arteriovenous malformation was suspected; however, appropriate treatment was precluded because of the viability of the ectopic gestation. Sonographic examination revealed a morbidly adherent placenta, and attempt to resect the mass laparoscopically was complicated by bleeding that required hysterectomy. This case illustrates a complication of the intervention performed to preserve the intrauterine gestation in case of HCSP. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 46 :227–230, 2018  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