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   25395篇
  免费   1671篇
  国内免费   48篇
耳鼻咽喉   202篇
儿科学   886篇
妇产科学   710篇
基础医学   3136篇
口腔科学   262篇
临床医学   3966篇
内科学   4590篇
皮肤病学   300篇
神经病学   2505篇
特种医学   528篇
外科学   2063篇
综合类   287篇
一般理论   65篇
预防医学   3702篇
眼科学   352篇
药学   1503篇
  1篇
中国医学   29篇
肿瘤学   2027篇
  2023年   97篇
  2022年   162篇
  2021年   434篇
  2020年   295篇
  2019年   457篇
  2018年   553篇
  2017年   435篇
  2016年   447篇
  2015年   496篇
  2014年   780篇
  2013年   1252篇
  2012年   1804篇
  2011年   1888篇
  2010年   1028篇
  2009年   897篇
  2008年   1739篇
  2007年   1834篇
  2006年   1812篇
  2005年   1852篇
  2004年   1765篇
  2003年   1675篇
  2002年   1549篇
  2001年   185篇
  2000年   127篇
  1999年   242篇
  1998年   340篇
  1997年   239篇
  1996年   236篇
  1995年   223篇
  1994年   193篇
  1993年   185篇
  1992年   120篇
  1991年   110篇
  1990年   86篇
  1989年   104篇
  1988年   88篇
  1987年   80篇
  1986年   82篇
  1985年   88篇
  1984年   119篇
  1983年   124篇
  1982年   137篇
  1981年   123篇
  1980年   115篇
  1979年   63篇
  1978年   65篇
  1977年   67篇
  1976年   48篇
  1975年   43篇
  1974年   43篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
We have examined the actions of vasoactive intestinal peptide (VIP) and certain other known immune modulators on a nuclear pool(s) of protein kinase C (PKC) in isolated rat splenocyte nuclei. Rat splenocyte nuclei pure by enzymatic and electron microscope criteria demonstrated a time- and concentration-dependent activation of nuclear PKC (nPKC) by VIP. A biphasic pattern of three bell-shaped curves was observed with peak phosphorylation at 10−15, 10−9 and 10−6M VIP. The phosphorylation of endogenous nuclear substrates was characterized as a PKC-mediated event by use of three known PKC inhibitors, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), sphingosine, and staurosporine, which produced similar phosphate incorporation measurements. Also, this activity was blocked with the addition of a monoclonal antibody to PKC. Inhibitors of the ability of VIP to activate nPKC included somatostatin, 8-bromo-cAMP, peripheral benzodiazepine receptor modulators, and the PKC inhibitors, sphingosine and staurosporine. These data have direct relevance to our knowledge of cell-mediated immunity.  相似文献   
52.
One of the most exciting developments in pediatric dermatology has been the use of the flashlamp-pumped, 585-nm, pulsed dye laser for treatment of vascular birthmarks. In many cases the results are miraculous. The increase in self-esteem and happiness of many children and adolescents has been overwhelming; for some, depression has been lifted, stuttering has ceased, social involvement has increased, and antidepressants have been discontinued. There are many success stories to tell.
Despite the remarkable effects of the pulsed dye laser and the medical and psychosocial indications for its use, the issue of pain control remains significant. We have no perfect outpatient pediatric anesthetic. Most methods carry either some risk or, if not hazardous, often are not very effective for controlling pain. Needless to say, a diversity of opinions exist on how to manage discomfort from this treatment modality. Therefore, we thought it would be useful to share the experiences and opinions of several dermatologists who have extensive experience with the pulsed dye laser.  相似文献   
53.
A 12-year-old girl developed a reversible myeloradiculopathy 1 week after a wasp sting. Delayed neurologic hypersensitivity reactions to Hymenopteran stings occur primarily in adults. Reactions involving both the peripheral and central nervous systems are extremely rare and have never been reported in a child. The mechanisms underlying this uncommon reaction may be related to age-dependent differences in immunologic responses.  相似文献   
54.
Multiple sclerosis (MS) is a highly variable, unpredictable disease and one of the most life-altering diagnoses a person can receive. Because it usually strikes in the prime of life, frequently progresses to disability, and has no cure, MS can make a strong emotional impact--not only on those who suffer from it, but also the healthcare team. Because MS is such a complex, multifaceted disorder, nurses who care for people with MS are faced with numerous clinical challenges. Many of the challenges are unique to MS, demanding, and time-consuming. Well-informed nurses are positioned to evaluate and explain the disease process, assist in the alleviation of symptoms, educate partners and families, and help improve quality of life. A case example can help nurses understand the real-life concerns of a person with MS.  相似文献   
55.
56.
Although present sonomicrometer techniques for measuring continuous changes in vascular diameter are very useful, two problems with available methods are difficulty in maintaining crystal alignment throughout an acute experiment and inability to measure absolute dimensions less than 1 mm. We have designed and ultrasonic dimension gauge system to over come these problems. The design uses a gate to pass a 20 MHz signal to a counter during the sonic travel time between crystals, and then converts the digital count to an analogue voltage. Interference from the transmitting impulse in the received signal was minimised using MOSFET transistors allowing measurements of absolute dimensions from 0.00 mm to 99.9 mm. An averaging effect which depends upon the asynchrony between the basic timer and the counter clock results in a resolution of at least 10 μm. Repeated calibration curves showed an accuracy of 2.5 μm without significant bias. Piezoelectric crystals were mounted to a lighweight stainless-steel clip to facilitate attachment to the vessel and to maintain the crystals in focus during changes in diameter. Mean and phasic diameters measured in the femoral artery with the clip device correlated well with measurements obtained with crystals sewn to the adventitia of the femoral artery of the dog (slope =0.97, r=0.99).  相似文献   
57.
Nursing is a profound human activity generally influenced by two dynamics--the relationship between patient and nurse and the scientific paradigm. Often overlooked, however, are the incongruities that arise between these two dynamics. The patient-nurse relationship encompasses sameness, closeness, and connection, whereas science requires distance, detachment, and differentiation to fulfil the demands of objectivity. The patient-nurse relationship is both profound and intangible, whereas science attends only to that which can be observed and measured. The authors explore these dynamics and the incongruities between them. They consider the demands made by science on the patient-nurse relationship and, conversely, the place of the patient-nurse relationship in the development of nursing as science. These issues are critical to the advancement and practice of nursing.  相似文献   
58.
Nancy Kluck, Scan J. O'Connor, Victor M. Hesselbrock, Allan Tasman and Donald Maier, Lance Bauer: Variation in Evoked Potential Measures Over the Menstrual Cycle: A Pilot Study. Prog. Neuro. Psychopharmacol. Biol. Psychiat. 1992. 16(6): 901–911.

1. 1. The P3 component of a visual event related potential (ERP) was studied for five consecutive weeks in six women with normal menstrual cycles. Serum concentrations of luteinizing hormone (LH), estradiol (E2) and progesterone were studied during the same period.

2. 2. Increases in P3 amplitude, although nonsignificant, were noted in the week preceding onset of menses.

3. 3. No significant changes in reaction times to target/nontarget stimuli were noted over the same time period.

Author Keywords: Event-related potentials; females; menstrual cycle  相似文献   

59.
We have previously demonstrated that alcoholics with transitory (< 72 hr) elevations in blood pressure (BP) during withdrawal continue to show residual cardiovascular dysregulation up to 4 weeks of abstinence. The present study replicates and extends these findings. Alcoholic inpatients were divided into three subgroups ( ns = 14) based on BP during the first 72 hr of withdrawal: transitory hypertensives (tHTs; BP > 160/95 mm Hg), transitory borderline hypertensives (tBHs; 140/90 BP < 160/95), and normotensives (NTs; all BPs < 140/90). All patients had normal resting pressures after 72 hr of withdrawal. At 3–4 weeks postadmission, the alcoholics and 14 nonalcoholic controls (CONTs) were tested at rest and during a 5-min handgrip task. The tHTs showed an exaggerated systolic and diastolic BP response to handgrip compared with NTs and CONTs, with tBHs intermediate ( ps < 0.05). Drinking history showed the tHTs had the highest reported level of alcohol consumption and severity of withdrawal symptoms ( ps < 0.05). Regression analyses indicated that consumption of hard liquor was the variable most predictive of admission BPs; further, parental history of hypertension potentiated this relationship for systolic BP. Age and consumption of nicotine and caffeine were not significant predictors of admission BP. The results suggest a persistent cardiovascular dysregulation in alcoholics showing transient hypertensive withdrawal BPs. These alcoholics may be at increased risk for future alcohol-related cardiovascular disorder.  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