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   5629篇
  免费   336篇
  国内免费   35篇
耳鼻咽喉   22篇
儿科学   202篇
妇产科学   71篇
基础医学   557篇
口腔科学   241篇
临床医学   548篇
内科学   1992篇
皮肤病学   36篇
神经病学   221篇
特种医学   580篇
外科学   519篇
综合类   97篇
一般理论   2篇
预防医学   407篇
眼科学   125篇
药学   191篇
中国医学   4篇
肿瘤学   185篇
  2023年   20篇
  2022年   22篇
  2021年   78篇
  2020年   37篇
  2019年   78篇
  2018年   130篇
  2017年   64篇
  2016年   80篇
  2015年   107篇
  2014年   162篇
  2013年   227篇
  2012年   297篇
  2011年   321篇
  2010年   266篇
  2009年   201篇
  2008年   288篇
  2007年   326篇
  2006年   259篇
  2005年   266篇
  2004年   249篇
  2003年   227篇
  2002年   206篇
  2001年   69篇
  2000年   72篇
  1999年   64篇
  1998年   171篇
  1997年   148篇
  1996年   141篇
  1995年   104篇
  1994年   95篇
  1993年   108篇
  1992年   60篇
  1991年   57篇
  1990年   49篇
  1989年   84篇
  1988年   77篇
  1987年   75篇
  1986年   69篇
  1985年   73篇
  1984年   46篇
  1983年   48篇
  1982年   56篇
  1981年   32篇
  1980年   51篇
  1979年   29篇
  1978年   33篇
  1977年   34篇
  1976年   34篇
  1975年   38篇
  1973年   20篇
排序方式: 共有6000条查询结果,搜索用时 265 毫秒
51.
The aim of this study was to compare 70 couples who had conceived by in- vitro fertilization (IVF) with 63 matched controls for the prevalence of anxiety and quality of attachment to the baby during pregnancy. Results for mothers showed no group differences using a global measure of anxiety, the Spielberger State-Trait Anxiety Inventory. However, pregnancy-specific measures revealed significantly higher levels of anxiety in IVF mothers about the survival and normality of their unborn babies, about damage to their babies during childbirth and about separating from their babies after birth. When IVF mothers were differentiated according to the number of treatment cycles, more differences in anxiety level were revealed, with most increases occurring in mothers who had experienced two or more treatment cycles. IVF fathers did not differ from controls on the global anxiety measure. No data on pregnancy-specific anxiety were available for fathers. Neither IVF mothers nor IVF fathers differed from controls on measures of attachment to the baby during pregnancy. Results are discussed in the context of the need for researchers to employ differentiated and issue-specific measures to identify concerns that may be unique to IVF couples. Clinical implications regarding the need for psychological support during pregnancy are also discussed.   相似文献   
52.
53.
54.
AIMS: No good predictive marker for the malignant transformation of potentially malignant oral lesions (PMOLs) is currently available. This study re-evaluated the value of p53 immunoexpression to predict malignant transformation of PMOLs after discounting possible confounding factors. METHODS: PMOLs from 18 patients who showed progression to carcinoma, 16 of the respective carcinomas, and PMOLs from 18 matched controls were evaluated by immunohistochemistry (IHC) for p53 expression. A mouse monoclonal antibody that detects wild-type and mutant forms of human p53 was used. The p53 immunostaining pattern was also correlated with the degree of dysplasia. RESULTS: Suprabasal p53 staining was significantly associated with high grades of dysplasia (p < 0.01). The specificity and positive predictive value (PPV) for malignant transformation of suprabasal p53 staining were superior to the assessment of dysplasia, but sensitivity was inferior. All carcinomas derived from PMOLs with suprabasal p53 showed strong p53 immunostaining. However, the absence of suprabasal p53 staining and/or dysplastic changes did not preclude malignant transformation in a considerable proportion of PMOLs. CONCLUSIONS: This study confirms and extends previous findings that suprabasal p53 immunoexpression has a high PPV for malignant transformation of PMOLs and can be used as a specific marker for lesions that are at high risk for malignant transformation. The absence of suprabasal p53 staining (that is, absence of, or basal, p53 staining) is non-informative for prognostic purposes. Because of its limited sensitivity, p53 IHC is not a substitute for the assessment of dysplasia in the evaluation of PMOLs. Instead, p53 IHC emerges as a clinically useful supplement of histopathological assessment in the prognosis of PMOLs.  相似文献   
55.
56.
57.
Increased antiphospholipid antibody prevalence has been demonstrated by a number of recent studies in in-vitro fertilization (IVF) patients but the potential effects of antiphospholipid antibodies on the different components of the reproductive process and the consideration of whether to test IVF patients for antiphospholipid antibodies are controversial. The present study was undertaken to investigate the possible association between the presence of circulating antiphospholipid antibodies (namely the lupus anticoagulant and anticardiolipin antibodies), among a series of 21 consecutive IVF patients having a clinical spontaneous abortion after their first embryo transfer. As a control group (n=42), the nearest IVF cycle resulting in an ongoing pregnancy before and after each miscarried IVF cycle (i.e. the closest cycles in temporal relationship to the index cycle) was used. One patient (4.8%) in the study group and two women (4.8%) among controls were seropositive for antiphospholipid antibodies. These low and similar seropositivity rates found in the two groups studied lead us to conclude that antiphospholipid antibodies testing in IVF patients should be considered only in those women having repeated failures of implantation/clinical abortion after embryo transfer but not in an infertile general population reaching an IVF programme.   相似文献   
58.
Despite the increasing attention paid to the role of social forces in determining health, most physicians finish their training ill-prepared to address these issues. The authors describe their efforts to fill that training gap for internal medicine residents at Oregon Health and Science University through a community-based social medicine curriculum, designed in 2006 in conjunction with community partners at Central City Concern (CCC), an organization addressing homelessness, poverty, and addiction in downtown Portland, Oregon. The challenge was to develop a curriculum that would (1) fit within the scheduling constraints of an established categorical internal medicine residency program, (2) give all internal medicine residents a chance to better understand how social forces affect health, and (3) help show how they, as health professionals, might intervene to improve health and health care. The authors maintain that by developing this curriculum with community partners--who took the lead in deciding what residents should learn about their community and how they should learn it--the residency program is providing a relatively brief but extremely rich opportunity for residents to engage the personal, social, and health-related issues experienced by clients served by CCC.The authors first provide a brief overview of the curriculum and describe how the principles and practices of community-based participatory research were used in its development. They then discuss the challenges involved in teaching medical residents about social determinants of health, how their academic-community partnership approaches those challenges, and the recently established methods of evaluating the curriculum.  相似文献   
59.
The objective was to demonstrate bioequivalence between s.c. and i.m. administration of Humegon (FSH/LH ratio 1:1) and Normegon (FSH/LH ratio 3:1). In two randomized, single-centre, cross-over studies, 18 healthy volunteers on each formulation were assigned to one of the two administration sequences. Subjects were given single doses of one of the above gonadotrophins after endogenous gonadotrophin production had first been suppressed using high-dose oral contraceptive. Subsequently, rate (Cmax, tmax) and extent (AUC) of absorption of follicle stimulating hormone (FSH) and luteinizing hormone (LH) were determined for 14 days. For Cmax and AUC, analysis of variance (ANOVA) was performed on log-transformed data and for tmax ANOVA was performed on ranks. Intramuscular and s.c. injections of Humegon were bioequivalent with respect to the main pharmacokinetic parameters, being AUC and Cmax of FSH absorption. Intramuscular and s.c. injections of Normegon were bioequivalent with respect to the AUC of FSH and not bioequivalent with respect to the Cmax of FSH. For tmax of FSH as well as for most LH variables of both preparations, bioequivalence could not be proven due to the high intra- and interindividual variability and/or concentrations being close to the detection limit. Thus, the main pharmacokinetic FSH variables after i.m. and s.c. administration of Humegon and Normegon were bioequivalent.   相似文献   
60.
A pilot study was designed to examine whether the outcome of embryo transfer in women with a hydrosalpinx might be improved by surgical drainage of the hydrosalpinx at the time of oocyte collection for in- vitro fertilization treatment. A comparative, controlled but retrospective analysis of the results was performed of all women with infective tubal damage aged <40 years old, who had ovulatory cycles, a normal uterus and a partner with normal spermatozoa. A standardized treatment regimen was used. A maximum of three embryos were transferred. Hydrosalpinx was defined by prior hysterosalpingography and/or laparoscopy with transcervical dye injection. A total of 237 embryo transfer cycles in women with hydrosalpinges (tubal distension not visible in 151, visible but not drained in 30 and drained in 56) were compared with 705 embryo transfer cycles in women with tubal disease but no hydrosalpinx. Results were analysed in the first three cycles but also separately in the first cycle to check for bias. Success rates were higher in the first cycle, but did not significantly influence overall differences. Implantation rates were significantly reduced overall in the hydrosalpinx group (8.0 versus 13.2% for controls; P < 0.001), being 8.3% (P < 0.01) in the subgroup without evident tubal distension and 7.5% (not significant) in the drained hydrosalpinx group. This study shows that tubal damage with distal occlusion is associated with a marked reduction in embryo implantation, even in the absence of obvious fluid distension. Surgical drainage of distended hydrosalpinges appears to offer no benefit.   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