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   2266篇
  免费   138篇
  国内免费   15篇
耳鼻咽喉   11篇
儿科学   96篇
妇产科学   36篇
基础医学   426篇
口腔科学   19篇
临床医学   299篇
内科学   457篇
皮肤病学   45篇
神经病学   227篇
特种医学   48篇
外科学   174篇
综合类   13篇
预防医学   211篇
眼科学   28篇
药学   190篇
中国医学   3篇
肿瘤学   136篇
  2023年   17篇
  2022年   18篇
  2021年   49篇
  2020年   32篇
  2019年   48篇
  2018年   65篇
  2017年   49篇
  2016年   55篇
  2015年   61篇
  2014年   89篇
  2013年   120篇
  2012年   186篇
  2011年   206篇
  2010年   107篇
  2009年   96篇
  2008年   163篇
  2007年   153篇
  2006年   145篇
  2005年   129篇
  2004年   108篇
  2003年   115篇
  2002年   92篇
  2001年   21篇
  2000年   15篇
  1999年   24篇
  1998年   26篇
  1997年   14篇
  1996年   17篇
  1995年   11篇
  1994年   12篇
  1993年   8篇
  1992年   7篇
  1991年   6篇
  1990年   8篇
  1989年   16篇
  1988年   10篇
  1987年   9篇
  1986年   8篇
  1985年   10篇
  1984年   6篇
  1982年   5篇
  1980年   7篇
  1979年   8篇
  1977年   7篇
  1976年   6篇
  1974年   4篇
  1973年   4篇
  1972年   4篇
  1971年   5篇
  1967年   5篇
排序方式: 共有2419条查询结果,搜索用时 375 毫秒
101.
Epileptic spasms and partial seizures as a single ictal event   总被引:2,自引:2,他引:0  
Pachatz C  Fusco L  Vigevano F 《Epilepsia》2003,44(5):693-700
PURPOSE: To investigate the phenomenon of epileptic spasms (ESs) associated with other seizure types in a single ictal event and to study the predictive value of this phenomenon regarding etiology and prognosis. METHODS: We selected retrospectively eight female and five male patients, who had ESs and other seizure types within a single seizure event and for whom a video-EEG recording of the phenomenon was performed in at least one situation. RESULTS: The seizure type associated with ESs was a partial seizure in all patients. We identified three groups with different seizure patterns regarding the temporal association of ES and partial seizures (PSs): (a) PS followed by ES; (b) PS appearing during a cluster of ESs without interrupting the cluster; and (c) complex seizure interaction with a succession of ESs and PSs in a close but variable temporal association. Underlying disorders included cortical dysplasia (three patients), complex cerebral malformations (two patients), and perinatal anoxic-ischemic injuries (two patients); four cases were classified as cryptogenic, and in two children, etiology was unknown, but prenatal origin was suspected. Outcome was poor in nine cases with intractable epilepsy; four cases had a favorable outcome, defined as complete cessation of epileptic seizures. CONCLUSIONS: The phenomenon of associated ESs and PSs as a single ictal event can be related to different etiologies and should not be considered distinctive for cortical malformations or severe brain damage. Different seizure patterns of associated ESs and PSs provide no hint for etiology or prognosis. Outcome is prevalently but not constantly unfavorable in patients with the phenomenon.  相似文献   
102.
Early maltreatment of children can lead to severe disorders in the regulation of behaviour and affect, alterations in awareness and distorted perception. In development-oriented psychotherapy, therapeutic interventions which are directed to regulating processes, decentration or mentalization, desomatization and symbolization of enacted messages play a central role. The results of early traumatization and of therapeutic interventions are portrayed, examining the multi-dimensional diagnosis and therapy of a dangerously aggressive 12-year-old boy as an example. From this, it becomes clear how, through new experiences with regulating others, he gradually surfaces from a world of annihilation and destruction and learns to survive and to live.  相似文献   
103.
To understand the origin and emergence of pathogenic bacteria, knowledge of the genetic inventory from their nonpathogenic relatives is a prerequisite. Therefore, the 2.11-megabase genome sequence of Wolinella succinogenes, which is closely related to the pathogenic bacteria Helicobacter pylori and Campylobacter jejuni, was determined. Despite being considered nonpathogenic to its bovine host, W. succinogenes holds an extensive repertoire of genes homologous to known bacterial virulence factors. Many of these genes have been acquired by lateral gene transfer, because part of the virulence plasmid pVir and an N-linked glycosylation gene cluster were found to be syntenic between C. jejuni and genomic islands of W. succinogenes. In contrast to other host-adapted bacteria, W. succinogenes does harbor the highest density of bacterial sensor kinases found in any bacterial genome to date, together with an elaborate signaling circuitry of the GGDEF family of proteins. Because the analysis of the W. succinogenes genome also revealed genes related to soil- and plant-associated bacteria such as the nif genes, W. succinogenes may represent a member of the epsilon proteobacteria with a life cycle outside its host.  相似文献   
104.
Freshly prepared soluble amyloid (Abeta) peptide has been reported to have vascular actions both in vitro and in vivo. This study was designed to examine the in vivo microvascular effects of beta in two skin microvascular model systems that might reflect possible short and long-term vascular effects of this peptide. Short-term vascular effects were examined using freshly prepared soluble Abeta(1-40) peptide superfused over naive rat skin microvasculature for 15 min. Peripheral microvascular functional changes in 9-months-old transgenic (Tg) mice overexpressing soluble beta in the brain, peripheral circulation and other tissues, were also examined. Microvascular responses were monitored using laser Doppler flowmetry from the base of a blister raised on the hind footpad of the animals. Endothelial-dependent and independent vasodilatation responses (VD) were examined using acetylcholine (ACh) and sodium nitroprusside (SNP) respectively. The exposure of na?ve rat skin microvasculature to Abeta(1-40) resulted in an immediate vasoconstriction (VC) that prevented ACh but not SNP from inducing a subsequent VD response. The vascular effects of Abeta(1-40) were reversed by antioxidants (superoxide dismutase and catalase) and an endothelin A (ETA) receptor antagonist (BQ-123). Tg mice overexpressing soluble Abeta and C100 showed significant reductions in both endothelial-dependent and endothelial-independent VD that were also reversed by antioxidants and BQ-123. In conclusion, this study provided evidence to support the notion of peripheral vascular effects of Abeta in vivo and present novel evidence for alterations in endothelial and smooth muscle cell function in peripheral skin microvasculature in Tg mice overexpressing Abeta and C100. We suggest that skin microvasculature is a useful model to examine the mechanisms underlying the vascular actions of the Abeta protein.  相似文献   
105.
106.
OBJECTIVES: The present experiments concerned the hypothesis that an intermittent, strong and extremely low frequency magnetic field reduces salivary melatonin levels and delays consecutively the nadirs of rectal temperature and heart rate. METHODS: Twelve healthy young men (18-25 years) participated in three randomly permuted sessions, which were performed as constant routines. The participants kept a strict bed rest over 26 h, air temperature was 20 degrees C, illumination < 30 lx, and sound level < 50 dBA. Salivary melatonin levels were determined hourly, rectal temperature and heart rate were registered continuously throughout. An intermittent magnetic field was administered in one session from 6 p.m. to 2 a.m. at 16.7 Hz, 0.2 mT and alternating on/off-periods of 15 s. This situation was compared with a control session without any additional stress. Another session was performed to determine the participants' ability to respond to a well-known melatonin-suppressing stress, namely bright light (1,500 lx, 10 p.m.-2 a.m.). RESULTS: Bright light inhibited melatonin synthesis in all 12 participants and delayed the nadirs of rectal temperature and heart rate. The only significant alteration that was associated with exposure to the magnetic field was a delay in the heart rate nadir, which was not mediated by an accordingly altered melatonin profile. CONCLUSION: The fact that the circadian rhythm of only the heart rate was altered indicates an internal dissociation which might constitute a health risk in the long run and needs to be investigated more extensively.  相似文献   
107.
OBJECTIVES: In East Germany, uranium mining was performed on a large scale for approximately 45 years (1946-1990). In particular, the poor working conditions during the post-war years until 1955 led to a high level of occupational diseases. The present study gives an overview of the occurrence of occupational diseases during the mining period as well as after uranium mining was stopped in 1990. METHODS: The number of occupational diseases which occurred during the mining period was calculated from the files of the former Wismut SDAG. Although exposure to uranium ceased after 1990, new cases of occupational diseases were recognized after that date. These were recorded by the German Federation Of Institutions For Statutory Accident Insurance And Prevention (HVBG). RESULTS AND CONCLUSIONS: Today, more than 35,000 cases of occupational diseases are known, and many more are expected. About two-thirds of them are lung diseases: 16,376 cases of silicosis/silicotuberculosis and 7,695 cases of bronchial carcinomas. The increase in the number of recognized occupational diseases is shown and discussed against the background of changes in criteria for recognition and in working conditions as well as the duration of the latency period.  相似文献   
108.
109.
110.
Recent case-control studies suggested that dairy product consumption is an important risk factor for testicular cancer. We examined the association between consumption of dairy products, especially milk, milk fat, and galactose, and testicular cancer in a population-based case-control study including 269 case and 797 controls (response proportions of 76% and 46%, respectively). Dietary history was assessed by food frequency questions for the index persons and through their mothers including diet 1 year before interview and diet at age 17 years. We used conditional logistic regression to calculate odds ratios as estimates of the relative risk (RR), 95% confidence intervals (95% CI), and to control for social status and height. The RR of testicular cancer was 1.37 (95% CI, 1.12-1.68) per additional 20 servings of milk per month (each 200 mL) in adolescence. This elevated overall risk was mainly due to an increased risk for seminoma (RR, 1.66; 95% CI, 1.30-2.12) per additional 20 milk servings per month. The RR for seminoma was 1.30 (95% CI, 1.15-1.48) for each additional 200 g milk fat per month and was 2.01 (95% CI, 1.41-2.86) for each additional 200 g galactose per month during adolescence. Our results suggest that milk fat and/or galactose may explain the association between milk and dairy product consumption and seminomatous testicular cancer.  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