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   2191篇
  免费   142篇
  国内免费   66篇
耳鼻咽喉   36篇
儿科学   94篇
妇产科学   47篇
基础医学   191篇
口腔科学   50篇
临床医学   242篇
内科学   501篇
皮肤病学   100篇
神经病学   79篇
特种医学   277篇
外科学   176篇
综合类   62篇
一般理论   1篇
预防医学   287篇
眼科学   24篇
药学   101篇
肿瘤学   131篇
  2021年   22篇
  2020年   19篇
  2019年   11篇
  2018年   19篇
  2017年   17篇
  2016年   20篇
  2015年   32篇
  2014年   34篇
  2013年   53篇
  2012年   65篇
  2011年   75篇
  2010年   51篇
  2009年   86篇
  2008年   104篇
  2007年   132篇
  2006年   102篇
  2005年   84篇
  2004年   93篇
  2003年   62篇
  2002年   67篇
  2001年   79篇
  2000年   56篇
  1999年   52篇
  1998年   76篇
  1997年   78篇
  1996年   81篇
  1995年   65篇
  1994年   52篇
  1993年   70篇
  1992年   35篇
  1991年   42篇
  1990年   49篇
  1989年   56篇
  1988年   36篇
  1987年   53篇
  1986年   29篇
  1985年   42篇
  1984年   40篇
  1983年   33篇
  1982年   28篇
  1981年   33篇
  1980年   27篇
  1979年   11篇
  1978年   17篇
  1977年   13篇
  1976年   8篇
  1975年   13篇
  1973年   9篇
  1969年   6篇
  1968年   7篇
排序方式: 共有2399条查询结果,搜索用时 171 毫秒
101.
First, second, and third trimester serum samples from 100 healthy pregnant women, umbilical cord serum samples from each delivery, and, for comparison, sera from 76 nonpregnant control subjects were assayed by indirect immunofluorescence for the presence of antibody to human epithelioid cell nuclei at titers of greater than or equal to 1:80. At serum dilutions of 1:80, the numbers of samples positive in the first, second, third trimester, and cord sera were 18, 21, 21, and 15, respectively. At serum dilutions of 1:160, the numbers of sera positive for antinuclear antibodies in each trimester and in cord sera were 9, 12, 9, and 8, respectively. All but three women with positive tests for antinuclear antibodies remained positive throughout their pregnancies. The frequencies with which antinuclear antibodies were found during pregnancy were not significantly higher than the frequency of antinuclear antibodies in nonpregnant female control subjects. A review of pregnancy outcome indicated that maternal antinuclear antibodies are not, in general, associated with abnormalities of the pregnancy or of the offspring.  相似文献   
102.
103.
In the introduction I express the need of introducing the point of view of Ethics when we are dealing with problems of science, technology, and especially medicine. In the first part of my presentation I deal with the problem of the value of human life, coming to the conclusion that human life might not be completely absolute, but is extremely important and “ceteris paribus” should be respected, and the problem of when it starts. Some of the main arguments are discussed. In this connection the question of abortion is briefly discussed. In the second part I deal with some problems related to human reproduction. Most people will be willing to support programmes for treating individuals with genetic disease; but at the same time the dangers of increasing depersonalization of the reproductive process are pointed out. In the third part I take up the problem of In Vitro Fertilisation. IVF has certainly brought benefits to some couples suffering from infertility, but at the same time it has raised quite a few human and moral problems. Is it permissible to fertilise an egg with a donor sperm, replacing the embryo in the womb? What about fertilising a donor egg with the husband's sperm? Is it acceptable to store or freeze embryos for future use? Is it moral to implant such an embryo in a woman who has no genetic relationship with the embryo? Is it moral to use surrogate mothers? Is it moral for ‘spare’ embryos to be killed or used as tissue for research? At the end I stress the need of dialogue between life sciences and ethics.  相似文献   
104.
In this study, the concepts of decision theory have been applied to a clinical obstetric controversy--the management of the selected mature breech presentation. We have reviewed in detail the literature published since 1974 and estimated the probabilities of various outcomes after different treatment strategies. We conclude that a policy of selected vaginal delivery will result in four perinatal deaths for every 1000 patients delivered. A similar probability of neurologic handicap, at least until discharge from hospital, can also be attributed to this method of delivery. These unfavorable outcomes were reported less frequently in more recent reports covering the years since 1974. In these cases, the probability of fetal death due to a trial of vaginal delivery is approximately two in 1000. Cesarean section rates have risen, however, and 18-40% of trials of labor for breech presentation now result in "emergency" cesarean section. Decision analysis has demonstrated that a policy of elective cesarean section for all cases would not necessarily increase maternal mortality and morbidity. Thus the greater dangers of emergency compared with nonelective surgery may abolish the advantages of attempting a vaginal delivery. Depending on the relative dangers of elective and emergency cesarean section, planned delivery becomes the safer option when 16-30% of trials of vaginal breech delivery are unsuccessful. The strength and limitations of this probabilistic approach to the breech presentation are discussed in detail.  相似文献   
105.
This research examines job satisfaction among 282 staff providing mental health care to 574 patients with serious mental illness. The mental health staff worked in 18 Department of Veterans Affairs inpatient and outpatient mental health care units at 12 Veterans Affairs Medical Centers located across the contiguous 48 states. The purpose was to identify (1) aspects of the health care context that were associated with provider job satisfaction and (2) administrative and organizational procedures/interventions that might sustain or improve provider job satisfaction. The association of provider job satisfaction with patients' functional status and symptom severity was tested in multilevel statistical models that accounted for provider and unit characteristics. Provider job satisfaction was found to be greater on smaller units and units with higher patient functioning and lower illness severity. Implications of these results are discussed.  相似文献   
106.
OBJECTIVES: We examined differences in HIV seroprevalence and the likely timing of HIV infection by birth region. METHODS: We analyzed unlinked HIV antibody data on 61 120 specimens from 7 public health centers in Los Angeles County from 1993 to 1999. RESULTS: Most (87%) immigrant clients were Central American/Mexican-born. HIV prevalence was similar for US- and foreign-born clients (1.8% [95% confidence interval (CI) = 1.7%, 1.9%] and 1.6% [95% CI = 1.5%, 1.8%], respectively). Seroprevalence was high among sub-Saharan African females and low among Asian/Pacific Islander males and females. For HIV-positive immigrants, the average age at and time since immigration were 20.6 years and 12.3 years, respectively. CONCLUSIONS: The relatively young age at arrival and long time since arrival for HIV-positive foreign-born clients suggest that most were infected after immigration.  相似文献   
107.
This study assessed symptoms, severity of illness functional level, insight into illness, and attitudes toward medication in a sample of psychiatric patients who were newly admitted to a state hospital. The patients were evaluated before and after treatment with atypical, conventional, or mixed (atypical plus conventional) antipsychotic medication regimens with the Brief Psychiatric Rating Scale (BPRS), the Clinical Global Impression, the Global Assessment of Functioning, the Scale to Assess Unawareness of Mental Disorder, and the Drug Attitude Inventory. Overall, the patients showed significant improvement in symptoms, severity of illness, functional level, and insight into their illness during the course of hospitalization. Their attitudes toward medications changed minimally during treatment. Only the patients who were treated with conventional antipsychotics showed significant improvement in their attitudes toward medication. However, the change was not large enough to differentiate the conventional antipsychotic treatment group from the other treatment groups.  相似文献   
108.
AIM: To demonstrate the magnetic resonance imaging (MRI) appearances of intact and ruptured Trilucent TM implants with imaging and surgical correlation. The appearances of the implant transponder artefact are also described MATERIALS AND METHODS: A retrospective review of the MRI findings in 34 patients with bilateral subpectoral Trilucent TM breast implants (Lipomatrix, Inc./Collagen Aesthetics International Inc., Neuchatel, Switzerland) was performed. Patients under implant surveillance and those with suspected implant rupture formed the study group. Imaging findings were correlated with surgical appearances. RESULTS: Surgical correlation was available in 53% of patients. Fifty per cent (18/36) of implants were intact at surgery, 50% (18/36) of implants were ruptured. Of the 18 ruptured implants, 17 were intracapsular ruptures and one an extracapsular rupture. The sensitivity of MRI for detection of intracapsular rupture in Trilucent TM breast implants was 82% specificity 76%, positive predictive value 78%, negative predictive value 81% and accuracy 79% in this study group. No case of implant rupture was obscured by the transponder artefact. Four implants were found to have 'pseudocapsules' at surgery (5.9%), the implants were intact with fluid present between the implant and capsule. Only one pseudocapsule was demonstrated on MRI. CONCLUSION: Magnetic resonance imaging is currently the most accurate technique for diagnosis of implant rupture in Trilucent TM breast implants. Transponder artefact does not appear to interfere with the assessment of implant rupture.  相似文献   
109.
Aspden K  van Dijk AA  Bingham J  Cox D  Passmore JA  Williamson AL 《Vaccine》2002,20(21-22):2693-2701
Rabies virus (RV) readily infects cattle and causes a fatal neurological disease. A stable vaccine, which does not require the maintenance of a cold chain and that is administered once to elicit lifelong immunity to rabies would be advantageous. The present study describes the construction of a live recombinant lumpy skin disease virus (LSDV) vaccine, expressing the glycoprotein of rabies virus (RG) and assessment of its ability to generate a humoral and cellular immune response against rabies virus in cattle. Cattle inoculated with the recombinant virus (rLSDV-RG) developed humoral immunity that was demonstrated in ELISA and neutralisation assays to RV. High titres of up to 1513IU/ml of RV neutralising antibodies were induced. In addition, peripheral blood mononuclear cells from rLSDV-RG-immunised animals demonstrated the ability to proliferate in response to stimulation with inactivated RV, whereas the animal vaccinated with wild type LSDV did not. This recombinant vaccine candidate thus has the potential to be used in ruminants as a cost-effective vaccine against both lumpy skin disease (LSD) and rabies.  相似文献   
110.
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