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   315005篇
  免费   18722篇
  国内免费   447篇
耳鼻咽喉   4571篇
儿科学   10874篇
妇产科学   10577篇
基础医学   47647篇
口腔科学   7940篇
临床医学   25873篇
内科学   59305篇
皮肤病学   6675篇
神经病学   22986篇
特种医学   12493篇
外国民族医学   55篇
外科学   49507篇
综合类   7943篇
现状与发展   1篇
一般理论   166篇
预防医学   21338篇
眼科学   7637篇
药学   22159篇
中国医学   827篇
肿瘤学   15600篇
  2021年   2499篇
  2019年   2487篇
  2018年   3902篇
  2017年   2868篇
  2016年   3325篇
  2015年   3801篇
  2014年   4967篇
  2013年   7772篇
  2012年   9876篇
  2011年   10256篇
  2010年   6605篇
  2009年   6003篇
  2008年   9426篇
  2007年   10352篇
  2006年   10121篇
  2005年   9726篇
  2004年   9394篇
  2003年   8822篇
  2002年   8463篇
  2001年   13968篇
  2000年   14317篇
  1999年   11984篇
  1998年   3262篇
  1997年   3013篇
  1996年   2827篇
  1995年   2704篇
  1994年   2485篇
  1992年   8698篇
  1991年   8866篇
  1990年   8657篇
  1989年   8421篇
  1988年   7686篇
  1987年   7401篇
  1986年   7046篇
  1985年   6802篇
  1984年   4986篇
  1983年   4286篇
  1982年   2597篇
  1979年   4642篇
  1978年   3391篇
  1977年   2888篇
  1976年   2645篇
  1975年   2976篇
  1974年   3520篇
  1973年   3503篇
  1972年   3260篇
  1971年   3072篇
  1970年   2966篇
  1969年   2699篇
  1968年   2669篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Infantile hemangiomas (IHs) are the most common benign tumor of infancy, characterized by a natural history of early proliferation in the first months of life to eventual involution during childhood, often with residual fibrofatty tissue. Once involution has been achieved, IHs do not typically recur. We present two cases of exogenous growth hormone therapy resulting in the recurrence of IHs in late childhood, supported by radiological, immunohistochemical, in vitro, and in vivo evidence.  相似文献   
53.
54.
55.
Psoriasis is a common chronic inflammatory skin disease, affecting about 3% of the general population and approximately 2.5 million people in France, where this study took place. The genital area may be affected, however prevalence is poorly understood, meaning we do not know exactly how commonly this occurs. While it affects quality of life, genital psoriasis is under-recognized, probably due to the reluctance of patients to discuss genital involvement and sexual quality of life. The aims of this study, called the GENIPSO study, were to determine the prevalence of genital psoriasis, its clinical characteristics (its symptoms), whether it is associated with a particular type of psoriasis, and its impact on quality of life. The study included 776 adults seeing their doctor for psoriasis between November 2016 and March 2017. Among them, 336 (43.2%) had genital psoriasis. All these patients were aware that they had psoriasis on their genitals (genital lesions) but only 135 (40%) had already had a genital medical examination. Genital lesions were associated with (linked to) male gender, more severe psoriasis, first developing psoriasis when aged over 20 years, psoriasis of the skin folds, psoriasis on the scalp, nail and external auditory (ear) canal, but they were not associated with obesity or psoriatic arthritis. Itching was the main symptom. Genital psoriasis was associated with reduced quality of life and sexual health. The study found that genital psoriasis has a high prevalence in patients seeing their doctors about their psoriasis generally, it affects quality of life and should be better taken into account by dermatologists for the best possible care for patients.  相似文献   
56.

Background Context

The concept of dynamic stabilization (DS) of the lumbar spine for treatment of degenerative instability has been introduced almost two decades ago. Dynamic stabilization follows the principle of controlling movement in the coronal plane by providing load transfer of the spinal segment without fusion and, at the same time, reducing side effects such as adjacent segment disease (ASD). So far, only little is known about revision rates after DS due to ASD and screw loosening (SL).

Purpose

The present study aimed to evaluate the longitudinal revision rates following dynamic pedicle screw stabilization in the lumbar spine and to determine specific risk factors predictive for ASD, SL, and overall reoperation in a large cohort with considerable follow-up.

Design

We carried out a post hoc analysis of a prospectively collected database in a level I spine center.

Patients Example

The patient sample comprised 283 (151 female/132 male) consecutive patients suffering from painful degenerative lumbar segmental instability with or without spinal stenosis who underwent DS of the lumbar spine (Ulrich Cosmic, Ulrich Medical, Ulm, Germany) between January 2008 and December 2011.

Outcome Measures

Longitudinal reoperation rate and risk factors predictive for revision surgery were evaluated.

Methods

We analyzed the longitudinal reoperation rate due to ASD and SL and overall reoperation. Risk factors such as age, gender, body mass index, lumbar lordosis (LL), number of segments, and number of previous surgeries were taken into account. Regular and mixed model logistic regressions were performed to determine risk factors for revision surgery on a patient and on a screw level.

Results

The mean age was 65.7±10.2 years (range 31–88). One hundred thirty-two patients were stabilized in 1 segment, 134 in 2 segments, 15 in 3 segments, and 2 patients in 4 segments. Reoperation rate for ASD and SL after 1 year was 7.4 %, after 2 years was 15.0%, and after a mean follow-up of 51.4±15 months was 22.6%. Reasons for revision were SL in 19 cases (6.6%), ASD in 39 cases (13.7%), SL and ASD in 6 cases, hematoma in 2 cases (0.7%), cerebrospinal fluid fistulae in 3 cases (1.1%), infection in 6 cases (2.1%), and implant failure in 1 case (0.4%). The patients' age, the number of stabilized segments, and the number of previous surgeries and postoperative LL had a significant influence on the probability for revision surgery.

Conclusions

Reoperation rates after DS of the lumbar spine are comparable with rigid fixations. The younger the patient and the more segments are involved, the lower the LL and the more previous surgeries were found, the higher was the risk of revision. Risk of revision was almost twice as high in men compared with women. We therefore conclude that for clear clinical indication and careful evaluation of preoperative imaging data, DS using the Cosmic system seems to be a possible option. The presented data will help to further tailor indication and patient selection.  相似文献   
57.
Introduction: Tamoxifen dominates the anti-estrogenic therapy in the early and metastatic breast cancer setting. Tamoxifen has a complex metabolism, being mainly metabolized by CYP2D6 into its 30–100 times more potent metabolite, endoxifen. Recently, a phase I study in which endoxifen as an orally z-endoxifen hydrochloride has been successfully evaluated.

Areas covered: the principal pharmacogenetic and non-genetic differences in the pharmacology of tamoxifen and endoxifen are evaluated. To this end, references from PubMed, Embase or Web of Science, among others, were reviewed As non-genetic factors, important differences and similarities such age, or adherence to tamoxifen therapy are comprehensively illustrated. Additionally, since CYP2D6 genotypes are considered the main limitation of tamoxifen, many studies have investigated the association between the worsened clinical outcomes in patients with non-functional CYP2D6 genotypes. In this review, an overview of the research on this field is presented. Also, a summary describing the literature about individualizing tamoxifen therapy with endoxifen concentrations and its limitations is listed.

Expert opinion: z-endoxifen hydrochloride is only investigated in the metastatic setting, still more research is required before its place in therapeutics is known. Similarly, monitoring tamoxifen efficacy based on endoxifen concentrations might not be overall recommended due to the limited evidence available.  相似文献   

58.
Introduction: There are at the minimum two major, quite different approaches to advance drug discovery. The first being the target-based drug discovery (TBDD) approach that is commonly referred to as the molecular approach. The second approach is the phenotype-based drug discovery (PBDD), also known as physiology-based drug discovery or empirical approach.

Area covered: The authors discuss, herein, the need for developing radiation countermeasure agents for various sub-syndromes of acute radiation syndromes (ARS) following TBDD and PBDD approaches. With time and continuous advances in radiation countermeasure drug development research, the expectation is to have multiple radiation countermeasure agents for each sub-syndrome made available to radiation exposed victims.

Expert opinion: The majority of the countermeasures currently being developed for ARS employ the PBDD approach, while the TBDD approach is clearly under-utilized. In the future, an improved drug development strategy might be a ‘hybrid’ strategy that is more reliant on TBDD for the initial drug discovery via large-scale screening of potential candidate agents, while utilizing PBDD for secondary screening of those candidates, followed by tertiary analytics phase in order to pinpoint efficacious candidates that target the specific sub-syndromes of ARS.  相似文献   

59.
Pharmaceutical Chemistry Journal - Use of formylindolylacetic acid as a reagent at the stage of preparing the glycosides of bis(indolyl)furan-2,5-diones and dioxane as solvent increased yields from...  相似文献   
60.
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