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   1550篇
  免费   108篇
  国内免费   7篇
耳鼻咽喉   28篇
儿科学   37篇
妇产科学   77篇
基础医学   210篇
口腔科学   14篇
临床医学   214篇
内科学   296篇
皮肤病学   28篇
神经病学   119篇
特种医学   37篇
外科学   190篇
综合类   15篇
一般理论   1篇
预防医学   162篇
眼科学   30篇
药学   90篇
中国医学   3篇
肿瘤学   114篇
  2023年   13篇
  2022年   32篇
  2021年   58篇
  2020年   46篇
  2019年   45篇
  2018年   47篇
  2017年   38篇
  2016年   42篇
  2015年   45篇
  2014年   57篇
  2013年   77篇
  2012年   83篇
  2011年   122篇
  2010年   66篇
  2009年   51篇
  2008年   74篇
  2007年   87篇
  2006年   82篇
  2005年   63篇
  2004年   64篇
  2003年   69篇
  2002年   44篇
  2001年   31篇
  2000年   26篇
  1999年   17篇
  1998年   14篇
  1997年   8篇
  1996年   13篇
  1995年   8篇
  1994年   6篇
  1993年   7篇
  1992年   11篇
  1991年   19篇
  1990年   14篇
  1989年   20篇
  1988年   5篇
  1987年   12篇
  1986年   20篇
  1985年   21篇
  1984年   16篇
  1983年   20篇
  1982年   6篇
  1981年   9篇
  1980年   7篇
  1979年   7篇
  1978年   10篇
  1977年   4篇
  1972年   4篇
  1971年   3篇
  1969年   3篇
排序方式: 共有1665条查询结果,搜索用时 15 毫秒
101.
Birchall L  Clark N  Taylor S 《Nursing times》2004,100(32):63, 65, 67
Since The Essence of Care (Department of Health, 2001) was launched there have been many publications about the document and the process of benchmarking. This paper will focus specifically on the implementation of the benchmark for pressure ulcers.  相似文献   
102.
Partnership working is integral to New Labour's approach to modernising health and social care services for vulnerable groups such as children with complex needs. This paper draws on an initiative from Cornwall and the Isles of Scilly in which strategic and operational change have been promoted across the health and social care community in order to provide co-ordinated assessment and care for children with complex needs and their families. The introduction of link workers has been central, key contacts for families and professionals alike who are drawn from a wide range of backgrounds. The political imperative for partnership, combined with the commitment and commonality of purpose of front-line staff, has proved sufficient to facilitate inter-professional working without many of the enabling factors that are often regarded as important, such as co-location or parity of status. However, a number of organisational barriers to sustainability remain and the degree to which a strong operational lead can secure the necessary breadth of strategic resource allocation and support remains questionable.  相似文献   
103.
Background/Purpose Laparoscopic cholecystectomy is the procedure of choice for patients with symptomatic cholelithiasis. This procedure is contraindicated in patients with gall-bladder cancer (GBC) because of fear of dissemination of the disease. One of the findings raising the suspicion of GBC is a thick-walled gallbladder (TWGB).Methods A prospective study of patients with TWGB was done over a period of 10 months at a tertiary-level referral hospital in northern India. We studied the clinical profiles, investigations (ultrasound [US] and computerized tomography [CT]) and management plans in these patients.Results A total of 60 patients were included in the study. After cholecystectomy, histopathology of gallbladders showed GBC in 2 (3.3%) patients. The remaining 58 patients had chronic cholecystitis, of whom 28 (48%) had xanthogranulomatous variant chronic cholecystitis. Cholecystectomy by the laparoscopic method was attempted in 46 (77%) patients and by open technique in the remaining 14 (23%) patients. Laparoscopic cholecystectomy was successful in 40 of the 46 (87%) patients in whom it was attempted. Obscure anatomy, suspicion of GBC, and bile duct injury were the causes of conversion, in the remaining 13% (6/46). None of the 11 patients who had a CT examination because of clinical or US suspicion of malignancy turned out to have GBC at final histology. Both the cases of GBC in this study were incidental findings on final histopathology.Conclusions Laparoscopic cholecystectomy can be successfully performed in the majority of patients with diffuse TWGB, with appropriate selection. There is, however, an increased chance of conversion to open cholecystectomy in these patients. If there is an intraoperative suspicion of GBC, early conversion to open cholecystectmy and frozen section/imprint cytology will help to decide the further treatment during surgery.  相似文献   
104.
Leukemia inhibitory factor: an important regulator of endometrial function   总被引:11,自引:0,他引:11  
PROBLEM: Leukemia inhibitory factor (LIF) is multifunctional cytokine that displays biological activities in different cells, including endometrial cells. The aim of this study is to describe implications of LIF on a physiological function of endometrium. METHOD OF STUDY: The role of LIF in the endometrial function is reviewed and summarized from the available literature. RESULTS: LIF plays an important role in a physiological function of endometrium. In human endometrial LIF expression depends on cellular localizations, steroid hormones, menstrual stages and a local cytokine network. Stronger LIF expression exists in an endometrial epithelium during a luteal phase of the menstrual cycle, which coincides with the time of an implantation. The impairments of the endometrial LIF expression may play a significant role in the pathological processes involving implantation and the infertility. CONCLUSIONS: There is a substantial evidence that LIF is a potential regulator of the endometrial function and might be one of the factors that play a key role in human reproduction.  相似文献   
105.
There is a national commitment to ensuring that, regardless of where patients live, they should be provided with an acceptable level of service in terms of quality, effectiveness and accessibility. Because of differences in the distributions of their populations, rural and urban areas present quite different challenges for the optimal design of health services and social care. However, this has not been fully acknowledged in the development of national policies to unify service standards. The problems of providing services in sparsely populated areas are not new. However, until the case for a rural premium in English health resource allocation is accepted, rural agencies must either tolerate lower levels of services (an option made difficult by the introduction of national service standards) or develop very different approaches to service delivery. To date, there has been little systematic knowledge about the extent of innovative rural practice, a paucity of evaluation of such initiatives and few opportunities to disseminate learning from one area to another. The present paper begins to address this deficit. Drawing upon a review of the formal literature and a comprehensive evaluation of projects developed within a rural Health Action Zone, it presents a typology of innovative responses at the health/social care interface. Examples of service innovations which fall into six broad categories are provided. These not only suggest possibilities for the transfer of good practice, but also the potential for future research.  相似文献   
106.
Contrast encoding for sinusoidal modulations of luminance contrast was investigated by intracellular recording in the intact salamander retina. In what appears to be the first study of this kind for vertebrate bipolar cells, responses of the central receptive-field mechanism of cone-driven cells to modulation of 3 Hz were analyzed quantitatively via both signal averaging and a Fast Fourier Transform (FFT) while the retina was light adapted to 20 cd/m2. Depolarizing and hyperpolarizing bipolar cells showed very similar encoding. Both responded with sinusoidal waveforms whose amplitude varied linearly with modulation depths ranging up to 7-8%. The slope of the modulation/response curve was very steep in this range. Thus, the contrast gain was high, reaching values of 6-7, and the half-maximal response was achieved at modulations of 9% or less. At modulations above approximately 15%, the responses typically showed strong compressive nonlinearity and the waveform was increasingly distorted. At maximum modulation, the higher harmonics of the FFT constituted about 30% of the amplitude of the fundamental. Measurements were also made for cones and horizontal cells. Both cell types showed predominantly linear responses and low contrast gain, in marked contrast to bipolar cells. These results suggest that the high contrast gain and strong nonlinearity of bipolar cells largely arise postsynaptic to cone transmitter release. Further experiments were performed to compare responses to contrast steps versus those to sinusoidal modulation. In the linear range, we show that the contrast gains of cones and horizontal cells are low and virtually identical for both steps and sinusoidal modulations. In bipolar cells, on the other hand, the contrast gain is about two times greater for steps than that for the 3-Hz sine waves. These results suggest that mechanisms intrinsic to bipolar cells act like a high-pass filter with a short time constant to selectively emphasize contrast transients over slower changes in contrast.  相似文献   
107.
108.
109.
Diabetes affects an increasingly large number of young men of reproductive age. Erectile and ejaculatory difficulties arise due to vascular and neuropathic problems. The treatment of these may have effects on fertility potential. Erectile dysfunction can be treated with mechanical devices and intracavernosal injections. Although these have not been shown to affect fertility directly, they may result in poor compliance and hence reduced frequency of ejaculation with subsequent deterioration in sperm quality. Other medical treatments may have a more direct effect. The phosphodiesterase (PDE) inhibitor pentoxifylline has been shown to affect sperm quality and early embryo development. Therefore, Viagra, also a PDE inhibitor, may affect sperm quality. There is conflicting evidence about this in the literature. Ejaculatory difficulties are also more common in diabetics although treatments such as Trucut testicular biopsy and intracytoplasmic sperm injection have improved the outlook for these patients. There is also some evidence that spermatogenesis is affected by diabetes and that patients have a reduced sperm motility and semen volume. Therefore, diabetes has a significant impact on the fertility of men with this disease both directly and indirectly. The extent of iatrogenic influence on the reduced fertility potential of these patients needs to be researched as a matter of urgency.  相似文献   
110.
OBJECTIVE: Premature atrial contractions are common in obstetrical practise but there is little information available on recommended management and mode of delivery. DESIGN: The aim of the study was to describe our clinical experience in the management of fetal arrhythmia including the indications for certain time and way of labour. MATERIALS AND METHODS: 128 fetuses with diagnosed supraventricular arrhythmia described as atrial extrasystole were examined. They were divided into 3 main groups: group I (84 fetuses) with single PAC, group II (37 fetuses) with quantitatively significant arrhythmia or accompanied by another kind of arrhythmia and group III (7 fetuses) associated with extracardiac abnormalities. RESULTS: Among 128 fetuses with supraventricular arrhythmia, 44 cases (31%) required systematic monitoring. Quantitatively significant arrhythmia was recognized in 15 cases, blocked bigeminy (2:1) in 2 fetuses, 10 cases were accompanied by another arrhythmias: 4x SVT, 4x sinus bradycardia, 2x premature ventricular contractions (PVC). There were 3 fetuses diagnosed with heart defects and 7 with extracardiac malformations. Fetal echocardiography revealed additional functional circulatory changes in 7 fetuses with premature atrial contractions. Myocarditis was recognized in 2 fetuses. The mode of delivery was analyzed in 128 cases. In the first group 27 patients (32%) underwent caesarean section, in the second group--23 (62%), in the third group 3 patients (43%), respectively. Cardiac indications for caesarean section equalled 22% of all the indications occurring in fetuses suffering from arrhythmia. CONCLUSIONS: Caesarean section is much more commonly performed among fetuses diagnosed with arrhythmia accompanied by another fetal anomalies comparing to the group of fetuses with isolated arrhythmia. Although there are no particular cardiac indications for such way of delivery, total amount of caesarean sections performed in that group is really great. Above all, it may suggest that the obstetrician is under pressure of stress while making decision concerning caesarean section performance, even when there are no other indications and the condition of fetus is stable enough.  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