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   4249篇
  免费   324篇
  国内免费   17篇
耳鼻咽喉   8篇
儿科学   120篇
妇产科学   81篇
基础医学   796篇
口腔科学   89篇
临床医学   401篇
内科学   737篇
皮肤病学   161篇
神经病学   537篇
特种医学   151篇
外科学   387篇
综合类   29篇
预防医学   415篇
眼科学   49篇
药学   287篇
中国医学   13篇
肿瘤学   329篇
  2024年   6篇
  2023年   37篇
  2022年   22篇
  2021年   127篇
  2020年   85篇
  2019年   131篇
  2018年   129篇
  2017年   128篇
  2016年   127篇
  2015年   169篇
  2014年   174篇
  2013年   263篇
  2012年   362篇
  2011年   359篇
  2010年   220篇
  2009年   195篇
  2008年   339篇
  2007年   330篇
  2006年   273篇
  2005年   245篇
  2004年   239篇
  2003年   169篇
  2002年   202篇
  2001年   27篇
  2000年   21篇
  1999年   31篇
  1998年   34篇
  1997年   18篇
  1996年   14篇
  1995年   11篇
  1994年   13篇
  1993年   11篇
  1992年   7篇
  1990年   6篇
  1989年   5篇
  1988年   4篇
  1987年   5篇
  1986年   3篇
  1984年   9篇
  1983年   4篇
  1982年   3篇
  1981年   4篇
  1980年   3篇
  1978年   2篇
  1977年   5篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1968年   3篇
  1962年   2篇
排序方式: 共有4590条查询结果,搜索用时 78 毫秒
1.

Purpose

To quantify eating disorder (ED) stability and diagnostic transition among a community-based sample of adolescents and young adult females in the United States.

Methods

Using 11 prospective assessments from 9,031 U.S. females ages 9–15 years at baseline of the Growing Up Today Study, we classified cases of the following EDs involving bingeing and purging: bulimia nervosa (BN), binge ED, purging disorder (PD), and subthreshold variants defined by less frequent (monthly vs. weekly) bingeing and purging behaviors. We measured number of years symptomatic and probability of maintaining symptoms, crossing to another diagnosis, or resolving symptoms across consecutive surveys.

Results

Study lifetime disorder prevalence was 2.1% for BN and roughly 6% each for binge ED and PD. Most cases reported symptoms during only one survey year. Twenty-six percent of cases crossed between diagnoses during follow-up. Among participants meeting full threshold diagnostic criteria, transition from BN was most prevalent, crossing most frequently from BN to PD (12.9% of BN cases). Within each disorder phenotype, 20%–40% of cases moved between subthreshold and full threshold criteria across consecutive surveys.

Conclusions

Diagnostic crossover is not rare among adolescent and young adult females with an ED. Transition patterns from BN to PD add support for considering these classifications in the same diagnostic category of disorders that involve purging. The prevalence of crossover between monthly and weekly symptom frequency suggests that a continuum or staging approach may increase utility of ED classification for prognostic and therapeutic intervention.  相似文献   
2.
Decreases in sex hormone levels with menopause may bring about a number of consequences in women's general health and sexual well-being, especially when levels decline suddenly and prematurely, as in surgical menopause. In addition to the well-established role of estrogens in preserving the biological basis of sexual response, there is emerging evidence that androgens are significant independent determinants affecting sexual desire, activity and satisfaction, as well as mood, energy and other components of women's health. Hypoactive sexual desire disorder (HSDD), a persistent absence of sexual fantasies or thoughts and/or desire for and receptivity to sexual activity that causes personal distress, is experienced by some postmenopausal women. Even though conventional hormone therapy with estrogens or estrogens and progestogens may be effective for vaginal atrophy, increasing vaginal lubrication and reducing dyspareunia, it has not been shown to consistently increase sexual desire or activity and many women with sexual dysfunction remain unresponsive. Several recent, large, phase III studies have shown that the addition of transdermal testosterone to conventional hormone therapy can be helpful in surgically menopausal women presenting with HSDD. After 24 weeks of treatment in these studies, testosterone-treated women experienced significantly greater increases in satisfying sexual activity and sexual desire, and greater decreases in distress, than placebo-treated women. Accurate clinical assessment and individualized management of sexual symptoms are fundamentally important for all menopausal women with HSDD or other sexual problems.  相似文献   
3.
This paper is concerned with mothers’ understandings of child health in their young babies. To explore how child health is depicted, explained and contextualised by mothers, altogether 29 mothers in Stockholm and London were interviewed through the baby's first months about day-to-day experiences of the baby's health and well-being. The analysis of the mothers’ accounts reveals how the mothers, in the process of assessing health, try to ‘read’ the bodily signs and reactions in their babies. Some major themes emerge on how the mothers identify and characterise threats to the health of the baby; here described as threats of abnormalities, threats to the survival of the baby, threats to the thriving of the baby and threats from illnesses. Notions of child health are discussed in relation to the ‘bodily’ and the ‘social’, and how the embodied images of child health are intertwined with the mothers’ presentations of themselves as responsible for the health of their children and as ‘worthy’ parents.  相似文献   
4.
Aconitum species have been used in China as an essential drug in Traditional Chinese Medicine (TCM) for 2000 years. Reviewing the clinical application of Aconitum, their pharmacological effects, toxicity and detoxifying measures, herb–herb interactions, clinical taboos, famous herbal formulas, traditional and current herbal processing methods based upon a wide range of literature investigations serve as a case study to explore the multidisciplinary implications of botanicals used in TCM. The toxicological risk of improper usage of Aconitum remains very high, especially in countries like China, India and Japan. The toxicity of Aconitum mainly derives from the diester diterpene alkaloids (DDAs) including aconitine (AC), mesaconitine (MA) and hypaconitine (HA). They can be decomposed into less or non-toxic derivatives through Chinese traditional processing methods (Paozhi), which play an essential role in detoxification. Using Paozhi, the three main forms of processed aconite – Yanfuzi, Heishunpian and Baifupian – can be obtained (CPCommission, 2005). Moreover, some new processing techniques have been developed in China such as pressure-steaming. The current development of fingerprint assays, in particular HPLC, has set a good basis to conduct an appropriate quality control for TCM crude herbs and their ready-made products. Therefore, a stipulation for a maximum level of DDA content of Aconitum is highly desirable in order to guarantee the clinical safety and its low toxicity in decoctions. Newly developed HPLC methods have made the accurate and simultaneous determination and quantification of DDA content interesting.  相似文献   
5.
The purpose of the present study was to investigate the influence of different drugs exhibiting different solubility on the viscoelastic properties and on the skin diffusion profile of a ringing gel. In a preliminary rheology study with the placebo gel predominating elastic properties were confirmed and a temperature influence was indicated. Fluconazole, fludrocortisone-acetate, flumethasone-pivalate, flutamide and flufenamic-acid each 1% (w/w) were incorporated into the preparation and oscillatory measurements were performed at temperatures of 25, 28, 32 and 37 degrees C. In all drug containing formulations a high elastic G' value predominated the viscous G' value. The highest G' value could be obtained with the incorporated flumethasone-pivalate. Additionally in almost all cases the G' values decreased with increasing temperature compared to the placebo gel. Additionally in vitro standard diffusion experiments using Franz-type cells and porcine skin were performed. Following rank order of the cumulative drug release after 48 h was obtained: fluconazole>flufenamic-acid>flumethasone-pivalate>flutamide>fludrocortisone-acetate. Furthermore an excellent chemical stability of all incorporated drugs was confirmed over 10 weeks.  相似文献   
6.
Dysphoric Rumination Impairs Concentration on Academic Tasks   总被引:3,自引:0,他引:3  
Three studies investigated the effects of dysphoric rumination on concentration during 3 academic tasks—reading a passage from the GRE (Study 1), watching a videotaped lecture (Study 2), and proofreading written text (Study 3). Before performing these tasks, dysphoric and nondysphoric students were induced either to ruminate about themselves or to distract themselves by focusing on neutral images (all three studies) or by planning an event (Study 1). The results supported our hypothesis that dysphoric rumination, relative to distraction, would impair students' concentration. In all 3 studies, dysphoric ruminators reported difficulty concentrating, as well as interfering thoughts, during the relevant academic tasks. Furthermore, dysphoric ruminators were slower than dysphoric distractors in completing the tasks—specifically, reading the GRE passage (Study 1) and answering lecture comprehension questions (Study 2). In addition, dysphoric participants who ruminated showed impaired reading strategies (Study 1), reduced comprehension of academic material (Study 2), and poor proofreading performance (Study 3). These findings suggest that, in addition to its documented adverse effects on mood, thinking, and problem-solving, self-focused rumination interferes with instrumental behavior. Implications for social relationships and job performance are discussed.  相似文献   
7.
The role of the basal ganglia in syntactic language processing was investigated with event-related brain potentials in fourteen neurologically impaired patients. Seven of these patients had basal ganglia lesions while 7 other patients primarily had lesions of the left temporo-parietal region excluding the basal ganglia. All patients listened to sentences that were either correct or included a verb argument structure violation. In previous experiments this type of violation elicited a biphasic pattern of an N400-P600 complex in young healthy participants. While the N400 may result from incorrect semantic-thematic role assignment, the P600 reflects the fact that verb information does not license the syntactic structure at present. Results of the patient experiment revealed a double dissociation: patients with left temporo-parietal lesions only show a P600, whereas patients with lesions of the basal ganglia showed no P600, but a negativity with extended duration that resembled an N400. The latter pattern not only confirms previous reports that the basal ganglia modulate the P600 but extends these results by showing that the N400 as a late semantic-thematic integration process appears partially modulated by the basal ganglia.  相似文献   
8.
Nonparasitic Cysts of the Liver: Results and Options of Surgical Treatment   总被引:5,自引:0,他引:5  
n = 9) should be regarded as a palliative measure. Within a short period, CT-guided aspiration led to recurrence of symptoms in seven of our patients. Standard treatment of NPHC is fenestration with widest possible excision of the cystic wall, which can be performed laparoscopically ( n = 10) or by the conventional surgical mode ( n = 54). One patient was initially operated by the laparoscopic technique but developed bleeding, which necessitated conversion to the open mode. Three patients underwent synchronous laparoscopic cholecystectomy. Recurrence rates were similar: 11% in the laparoscopically treated group and 13% in the group that underwent conventional open surgery. Conventional surgical treatment was always successful in cases of solitary cysts. However, in cases of multiple cysts measuring more than 5 cm, conventional surgery was followed by recurrence of symptoms in 26% of patients (7/27), who then had to undergo a second operation. Partial resection of the liver ( n = 9) was successfully performed in cases of polycystic disease ( n = 5) with concomitant enlargement of the organ as well as in cases of large solitary cysts of the left lobe of the liver ( n = 4). In patients in whom we found that the cysts communicated with the ductal system ( n = 3), we performed a cystojejunostomy to drain the bile. The complication rate was low. In addition to frequent postoperative ascites, which necessitated no further intervention, we observed infectious complications in four patients. Twenty patients (22%) expired during a mean follow-up period of 6.2 years. Interestingly, deaths were frequently associated with malignancy (11/20). After fenestration of multiple cysts measuring > 5 cm, the patients are at high risk for recurrence. Hence partial resection of the liver is an excellent therapeutic alternative in selected patients with polycystic disease and massive enlargement of the organ in whom the disease could not be controlled by simple fenestration. The results of this study show that laparoscopic fenestration should replace the conventional surgical technique as the gold standard in cases of NPHC because the laparoscopic technique is less stressful for the patient and is associated with a rate of success similar to that of the conventional technique.  相似文献   
9.
Introduction and background A 3-year-old Bosnian girl with a large symptomatic brainstem and multiple supratentorial cavernous angiomas, who underwent neurosurgical treatment, is presented. As multiple cavernomas are more common in familial cases, genetic analyses and neuroradiological imaging were performed in the patient and her parents to see whether there was any evidence for inheritance. This information is important for genetic counseling and provision of medical care for at-risk relatives. Currently, no recommendation is available on how to manage these cases.Results Genetic analyses demonstrated a novel CCM1 frameshift mutation (c.1683_1684insA; p.V562SfsX6) in the child and the asymptomatic 27-year-old mother. Sensitive gradient-echo magnetic resonance imaging of the mother revealed multiple supratentorial lesions, whereas analogous imaging of the father showed no pathological findings.Conclusion This case exemplifies that seemingly sporadic cases with multiple lesions might well be hereditary and that presymptomatic genetic testing of family members may identify relatives for whom clinical and neuroradiological monitoring is indicated.  相似文献   
10.
Identification of a 28 kDa lychee allergen as a triose-phosphate isomerase   总被引:2,自引:0,他引:2  
The aim of this study was to investigate the allergenic potency of the exotic fruit lychee (Litchi chinensis SONN.). For this purpose the lychee protein extract was separated by ion exchange chromatography and a purified allergen with a molecular weight of 28 kDa was identified by N-terminal sequencing and peptide mass fingerprinting. Both methods determined the lychee allergen as a triose-phosphate isomerase. To this protein 67% of patients showed allergic reactions respectively IgE binding of their sera. Similar enzymes from other plants were also recognized as allergens.  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