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   31581篇
  免费   1845篇
  国内免费   99篇
耳鼻咽喉   251篇
儿科学   1092篇
妇产科学   915篇
基础医学   3562篇
口腔科学   389篇
临床医学   5797篇
内科学   5274篇
皮肤病学   343篇
神经病学   3104篇
特种医学   599篇
外国民族医学   1篇
外科学   3004篇
综合类   293篇
现状与发展   1篇
一般理论   50篇
预防医学   4420篇
眼科学   443篇
药学   1843篇
中国医学   33篇
肿瘤学   2111篇
  2023年   183篇
  2022年   222篇
  2021年   586篇
  2020年   420篇
  2019年   649篇
  2018年   803篇
  2017年   557篇
  2016年   631篇
  2015年   669篇
  2014年   984篇
  2013年   1585篇
  2012年   2284篇
  2011年   2418篇
  2010年   1279篇
  2009年   1124篇
  2008年   2183篇
  2007年   2379篇
  2006年   2266篇
  2005年   2201篇
  2004年   2027篇
  2003年   1951篇
  2002年   1865篇
  2001年   216篇
  2000年   180篇
  1999年   278篇
  1998年   371篇
  1997年   309篇
  1996年   244篇
  1995年   274篇
  1994年   213篇
  1993年   210篇
  1992年   131篇
  1991年   136篇
  1990年   134篇
  1989年   111篇
  1988年   102篇
  1987年   94篇
  1986年   92篇
  1985年   103篇
  1984年   124篇
  1983年   126篇
  1982年   144篇
  1981年   139篇
  1980年   118篇
  1979年   56篇
  1978年   71篇
  1977年   61篇
  1976年   47篇
  1975年   36篇
  1974年   38篇
排序方式: 共有10000条查询结果,搜索用时 374 毫秒
91.
92.
Three patients,with known brain injury and neuropsychological impairments, are followed through an individualized cognitive rehabilitation programme and post discharge from the treatment programme. Single Photon Emission Computed Tomography (SPECT) of the brain was employed to evaluate resting relative cerebral blood flow (rCBF) during the process of recovery from brain injury. All patients experienced significant improvements on measures of neuropsychological functioning and improvements in rCBF during this longitudinal study. The specific changes in rCBF appear to be related to the location of the patient s brain injury and strategies particular to cognitive rehabilitation therapy. Continued improvements in rCBF, functional abilities, and cognitive skills were documented in these three cases up to 45 months post brain injury.  相似文献   
93.
Both salt-loading studies and reports of free-living populations find that urinary calcium excretion increases approximately 1 mmol (40 mg) for each 100 mmol (2300 mg) increase in dietary sodium in normal adults. Renal calcium stone-formers with hypercalciuria appear to have greater proportional increases in urinary calcium (approximately 2 mmol) per 100 mmol increase in salt intake. Thus, reduction of dietary NaCl may be a useful strategy to decrease the risk of forming calcium-containing kidney stones.  相似文献   
94.
Background: Many studies have addressed the effect of the timing of surgery for breast cancer relative to menstrual cycle phase, with conflicting results. Explanations for the possibility that survival could be altered by the appropriate timing of breast cancer surgery in humans remain speculative. Methods: We examined the expression of three estrogen related proteins (c-erbB-2, cathepsin D, pS2) in the breast tumors from 69 premenopausal women sampled in different phases of the menstrual cycle. Data on S-phase fraction and hormone receptor expression were also analyzed. Immunohistochemical assays were used to measure the proteins of interest. S-phase fraction was determined by flow cytometry. Analyses were performed based on fraction of cells staining positive for the protein, density of stain, and a histoscore that combined both fraction of positive cells and density. Results: We found no differences in c-erbB-2, cathepsin D, hormone receptor, or S-phase levels in tumors sampled in the follicular versus luteal phase, or perimenstrual versus periovulatory phase. The exception was pS2, which was expressed at greater levels during the luteal than during the follicular phase of the cycle (p<0.01); but there was no difference in pS2 expression when the patients were classified as periovulatory versus perimenstrual. Conclusions: Our findings do not support a variation in c-erbB-2, cathepsin D, S-phase fraction, or receptor expression as an explanation for the differences in breast cancer prognosis when surgery is timed by menstrual cycle phase. The finding that pS2 (an indicator of hormone sensitivity, and possibly better prognosis) is expressed at higher levels in tumor samples during the luteal phase suggests that the biologic profile of breast tumors may vary with the menstrual cycle and that these variations deserve further study.  相似文献   
95.
ABSTRACT: Programs for preventing violence among youth should be evaluated to determine if they are effective. Nurses' logs appear to be a useful tool for evaluating school-based violence prevention programs. The logs provide a record of students' visits to the school nurse that can be used to determine if a violence prevention program is associated with a reduction in fighting—and other injury-related nurse visits. This method has many strengths: it is simple and inexpensive, it does not interrupt the school routine, it permits school-level rather than student-level data collection, it provides a ready "baseline," and it allows continuous data collection. However, potential limitations do exist. For example, the method may provide insufficient information and may be affected by factors unrelated to the intervention. School officials can increase the usefulness of the logs by encouraging standardization and providing training in their use.  相似文献   
96.
Neonatal rat motoneurones are electrically coupled via gap junctions and the incidence of this coupling declines during postnatal development. The mechanisms involved in this developmental regulation of gap junctional communication are largely unknown. Here we have studied the role of NMDA receptor-mediated glutamatergic synaptic activity in the regulation of motoneurone coupling. Gap junctional coupling was demonstrated by the presence of graded, short latency depolarising potentials following ventral root stimulation, and by the transfer of the low molecular weight tracer Neurobiotin to neighbouring motoneurones. Sites of close apposition between the somata and/or dendrites of the dye-coupled motoneurones were identified as potential sites of gap junctional coupling. Early postnatal blockade of the NMDA subtype of glutamate receptors using the non-competitive antagonist dizocilpine maleate (MK801) arrested the developmental decrease in electrotonic and dye coupling during the first postnatal week. These results suggest that the postnatal increase in glutamatergic synaptic activity associated with the onset of locomotion promote the loss of gap junctional connections between developing motoneurones.  相似文献   
97.
98.
Background: The authors conducted a randomized controlled trial to determine whether parental presence during induction of anesthesia (PPIA) is associated with parental physiologic and behavioral manifestations of stress.

Methods: Children and their parents (N = 80) were randomly assigned to one of three groups: (1) PPIA; (2) PPIA plus 0.5 mg/kg oral midazolam; and (3) control (no PPIA or midazolam). The effect of the group assignment on parental heart rate (HR), parental blood pressure, and parental skin conductance level (SCL) were assessed. Both parental HR and parental SCL were monitored continually. Anxiety of the parent and child was also assessed.

Results: Parental HR increased from baseline until the induction of anesthesia (P = 0.001). A group-by-time effect (P = 0.005) was also found. That is, throughout the induction period there were several time points at which parents in the two PPIA groups had a significantly higher HR than did parents in the control group (P < 0.05). Similarly, SCL was found to increase in all parents from baseline until induction of anesthesia (P = 0.001). Significant group differences in SCL changes over time were found as well (P = 0.009). State anxiety and blood pressure following induction of anesthesia did not differ significantly between groups (P = nonsignificant). Examination of parental Holter data revealed no rhythm abnormalities and no electrocardiogram changes indicating ischemia.  相似文献   

99.
Nonmotor symptoms (NMS) of Parkinson's disease (PD) are not well recognized in clinical practice, either in primary or in secondary care, and are frequently missed during routine consultations. There is no single instrument (questionnaire or scale) that enables a comprehensive assessment of the range of NMS in PD both for the identification of problems and for the measurement of outcome. Against this background, a multidisciplinary group of experts, including patient group representatives, has developed an NMS screening questionnaire comprising 30 items. This instrument does not provide an overall score of disability and is not a graded or rating instrument. Instead, it is a screening tool designed to draw attention to the presence of NMS and initiate further investigation. In this article, we present the results from an international pilot study assessing feasibility, validity, and acceptability of a nonmotor questionnaire (NMSQuest). Data from 123 PD patients and 96 controls were analyzed. NMS were highly significantly more prevalent in PD compared to controls (PD NMS, median = 9.0, mean = 9.5 vs. control NMS, median = 5.5, mean = 4.0; Mann-Whitney, Kruskal-Wallis, and t test, P < 0.0001), with PD patients reporting at least 10 different NMS on average per patient. In PD, NMS were highly significantly more prevalent across all disease stages and the number of symptoms correlated significantly with advancing disease and duration of disease. Furthermore, frequently, problems such as diplopia, dribbling, apathy, blues, taste and smell problems were never previously disclosed to the health professionals.  相似文献   
100.
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   
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