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   192088篇
  免费   1910篇
  国内免费   101篇
耳鼻咽喉   1362篇
儿科学   7170篇
妇产科学   3371篇
基础医学   18915篇
口腔科学   2458篇
临床医学   14308篇
内科学   34055篇
皮肤病学   1118篇
神经病学   17845篇
特种医学   9377篇
外科学   30077篇
综合类   2455篇
一般理论   10篇
预防医学   20027篇
眼科学   3020篇
药学   10493篇
中国医学   710篇
肿瘤学   17328篇
  2023年   184篇
  2022年   358篇
  2021年   690篇
  2020年   415篇
  2019年   631篇
  2018年   22467篇
  2017年   17737篇
  2016年   19906篇
  2015年   1461篇
  2014年   1523篇
  2013年   1697篇
  2012年   8308篇
  2011年   22401篇
  2010年   19505篇
  2009年   12168篇
  2008年   20542篇
  2007年   22679篇
  2006年   1509篇
  2005年   3029篇
  2004年   4086篇
  2003年   5024篇
  2002年   3150篇
  2001年   373篇
  2000年   484篇
  1999年   242篇
  1998年   411篇
  1997年   354篇
  1996年   233篇
  1995年   205篇
  1994年   213篇
  1993年   160篇
  1992年   83篇
  1991年   136篇
  1990年   177篇
  1989年   130篇
  1988年   111篇
  1987年   94篇
  1986年   76篇
  1985年   76篇
  1984年   68篇
  1983年   60篇
  1982年   74篇
  1981年   43篇
  1980年   77篇
  1979年   36篇
  1976年   32篇
  1974年   31篇
  1938年   61篇
  1932年   58篇
  1930年   54篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
The purpose of the study was to determine the epidemiological relationships in three unrelated cases of neonatal late-onset Group B streptococcal (GBS) disease and maternal breast-milk infection with GBS. All deliveries were by cesarean section; case 1 was at term, and cases 2 and 3 were at 32- and 33-wk gestation, respectively. Case 1 relates to a mother with clinical mastitis and recurrent GBS infection in a 20-day-old male infant. Following antibiotic therapy and cessation of breast-feeding, the infant recovered without sequelae. Case 2 refers to a mother with clinical mastitis and the occurrence of late-onset GBS disease in 5-wk-old male twins. Despite intervention, one infant died and the second became ill. Following antibiotic therapy and cessation of breast-feeding, the surviving infant recovered without sequelae. Case 3 refers to a mother with sub-clinical mastitis and late-onset GBS infection occurring in a 6-day-old female twin. Following intervention, the infant recovered but suffered a bilateral thalamic infarction resulting in developmental delay and a severe seizure disorder. Following recovery of GBS from an inapparent mastitis and cessation of breast-feeding, the second infant remained well. Blood cultures from all affected infants and maternal breast milk were positive for GBS. Epidemiological relationships between neonatal- and maternal-derived GBS isolates were confirmed by a random amplified polymorphic DNA polymerase chain reaction assay (RAPD-PCR). This study is significant in that it has demonstrated that maternal milk (in cases of either clinical or sub-clinical mastitis) can be a potential source of infection resulting in either late-onset or recurrent neonatal GBS disease.  相似文献   
122.
123.
A patient-centered paradigm for clinical research and medical care is presented as a solution to the problem of declining innovation and increasing costs and development time in the pipeline for new therapies. Fundamental differences in values and motivations among scientists, clinicians, industry sponsor, and patients in neurotherapeutics provide a framework for analysis of ethical conflicts and the loss of public confidence in medical research. Parkinson advocates’ views on clinical trial participation, perceived risks and benefits, placebo controls, and sham surgery are presented. These views reflect the sense of urgency and the unique perspective that comes from living with this progressive, debilitating condition full time. A patient-centered paradigm that includes authentic voices of patients as collaborators at every stage of development will help to resolve conflicts, build trust, recruit trial participants, and accelerate new therapies. Key elements are adaptive clinical trial methods and the development of information technology for the assessment of outcomes and surveillance of safety over the life cycle of a medical product. Supported by the Parkinson’s Disease Foundation, the Parkinson Pipeline Project is a grassroots group of Parkinson’s patients whose goal is to represent an authentic voice for patients in the treatment development process. This group promotes education and communication between members of the Parkinson’s community and active stakeholders in medical research, industry, and regulatory agencies. Its members are an example of a new breed of knowledgeable consumers, armed with first-hand access to research findings and reinforced by on-line connections to like-minded peers throughout the world.  相似文献   
124.
Recent reports of sexually transmitted infection-rate increases among men indicate the need for renewed study of male sexual risk behavior to aid development of updated and novel risk reduction interventions. Men who have childhood sexual abuse (CSA) histories consistently report frequent sexual risk behavior. The objective of this sturdy is to explore whether posttraumatic stress disorder (PTSD) and depression are moderators and/or mediators of the association between CSA and sexual risk in adult men. A cross-sectional survey study employing random digit dial recruitment was administered to men aged 18–49 years from Philadelphia County. Two bundred ninety eight men were recruited and screened for CSA history, administered items from the Posttraumatic Stress Diagnostic Scale (PDS) and Center for Epidemiologic Studies—Depression (CES-D), and asked to estimate their number of lifetime sexual partners (LSPs). Effects of sociodemographic characteristics, CSA, PTSD, and depression on the number of LSPs were modeled using Poisson regression. Results show that 197 (66%) men participated; 43 (22%) had CSA histories. CSA was significantly associated with PTSD/depression (P=.03). Four sociodemographic variables (age, race, sexual identity, and education), CSA (incidence rate ratio, IRR=1.47, P<.001), PTSD (IRR=1.19, P=.04), depression (IRR=1.29, P=.001), all 2-way interactions, and the 3-way CSA/PTSD/depression interaction (IRR=11.00, P<.001) were associated with the number of LSPs (R2=0.27). In conclusion, sexual partnership patterns unique to men with CSA histories and comorbid PTSD/depression appear to lead to substantially higher numbers of LSPs. Estimates of this relationship may have been biased toward the null by underreporting that can occur with phone surveys. Cross-sectional studies do not support causal inferences; however, the identification of a moderating and mediating influence of PTSD/depression on the relationship between CSA and sexual risk behavior is important and suggests the need for future studies with larger samples that examine trajectories for CSA, psychiatric illness, and sexual partnerships.  相似文献   
125.
The effectiveness of organizational interventions in reducing the adverse consequences of work–family conflict has produced mixed findings. This paper examines the relationship between the use of organizational ‘family friendly’ resources (such as crèche facilities, flexible working hours, and job sharing), with levels of work–family conflict, and job and family satisfaction over time. Using structural equation modelling, these associations were tested in 398 employed men and women who each completed a self‐report questionnaire administered on two occasions. The use of organizational interventions directly predicted increased levels of concurrent (Time 1) work–family interference and increased levels of subsequent (Time 2) job satisfaction. Both organizational interventions and family interventions (i.e. support) positively predicted subsequent family satisfaction. The research demonstrates that the provision of organizational ‘family‐friendly’ practices will produce improved psychological outcomes for employees. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
126.

Background  

Induction of apoptosis is one strategy for treatment of prostate cancer. The Shb adapter protein has been found to regulate apoptosis in various cell types and consequently human prostate cancer 3 (PC3) cells were transfected to obtain cells overexpressing Shb in order to increase our understanding of the mechanisms regulating PC3 cell apoptosis.  相似文献   
127.
128.
129.
Drug use and HIV infection may affect sex hormone levels in women. One hundred and ninety-six women with and without a history of illicit drug use (50 HIV-negative and 148 HIV-infected), with regular menses, who never used antiretrovirals, were evaluated. Luteinizing hormone levels were significantly higher in women with a CD4 cell count <200/microl (p < 0.002). Current methadone use was associated with lower levels of total testosterone (p = 0.03) and higher levels of prolactin (p = 0.002); mean estradiol levels were 43% lower in women who used intravenous drugs (p < 0.001). Alcohol and crack cocaine use was not associated with sex hormone levels. Age, race, body mass index and degree of HIV immunosuppression were also associated with differences in sex hormone levels.  相似文献   
130.
Objective The purpose of this study is to analyze clinical aspects and disease-free survival (DFS) in children less than 3 years of age diagnosed with low-grade astrocytoma. Methods In a period of 24 years (1980–2004), a total of 43 (5.4%) children were registered with these characteristics. Twenty-three patients had pilocytic astrocytoma, 18 diffused, and 2 mixed. Thirty-one (72.1%) children had incomplete surgical tumor resection and 12 (27.9%) had a complete tumor resection. Twelve (27.9%) patients had cranial radiotherapy and 17 (39.5%) received chemotherapy. Overall survival was recorded in 23 (53%). DFS was 50% at 250 months of follow-up for the whole group. DFS for the supratentorial group was 60% at 250 months, whereas, for the infratentorial, it was 22% at 120 months (p = 0.008). Conclusion The only favorable prognostic pattern was the supratentorial presentation. Radiotherapy and chemotherapy did not alter the outcome.  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