全文获取类型
收费全文 | 11749篇 |
免费 | 1293篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 117篇 |
儿科学 | 416篇 |
妇产科学 | 240篇 |
基础医学 | 1476篇 |
口腔科学 | 219篇 |
临床医学 | 1263篇 |
内科学 | 2022篇 |
皮肤病学 | 140篇 |
神经病学 | 847篇 |
特种医学 | 427篇 |
外国民族医学 | 1篇 |
外科学 | 1299篇 |
综合类 | 226篇 |
一般理论 | 3篇 |
预防医学 | 2837篇 |
眼科学 | 176篇 |
药学 | 699篇 |
中国医学 | 4篇 |
肿瘤学 | 648篇 |
出版年
2022年 | 93篇 |
2021年 | 139篇 |
2020年 | 170篇 |
2019年 | 142篇 |
2018年 | 247篇 |
2017年 | 193篇 |
2016年 | 195篇 |
2015年 | 242篇 |
2014年 | 291篇 |
2013年 | 418篇 |
2012年 | 474篇 |
2011年 | 442篇 |
2010年 | 341篇 |
2009年 | 348篇 |
2008年 | 453篇 |
2007年 | 467篇 |
2006年 | 490篇 |
2005年 | 471篇 |
2004年 | 439篇 |
2003年 | 373篇 |
2002年 | 446篇 |
2001年 | 435篇 |
2000年 | 391篇 |
1999年 | 395篇 |
1998年 | 270篇 |
1997年 | 300篇 |
1996年 | 307篇 |
1995年 | 243篇 |
1994年 | 146篇 |
1993年 | 211篇 |
1992年 | 269篇 |
1991年 | 195篇 |
1990年 | 229篇 |
1989年 | 234篇 |
1988年 | 208篇 |
1987年 | 199篇 |
1986年 | 171篇 |
1985年 | 167篇 |
1984年 | 136篇 |
1983年 | 140篇 |
1982年 | 90篇 |
1981年 | 99篇 |
1980年 | 86篇 |
1979年 | 125篇 |
1978年 | 113篇 |
1977年 | 75篇 |
1976年 | 84篇 |
1975年 | 82篇 |
1974年 | 90篇 |
1971年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
C Allen C F Stevens 《Proceedings of the National Academy of Sciences of the United States of America》1994,91(22):10380-10383
Transmission at individual synaptic contacts on CA1 hippocampal pyramidal neurons has been found to be very unreliable, with greater than half of the arriving presynaptic nerve impulses failing to evoke a postsynaptic response. This conclusion has been reached using the method of minimal stimulation of Schaffer collaterals and whole cell recording in hippocampal slices; with minimal stimulation only one or a few synapses are activated on the target neuron and the behavior of individual synapses can be examined. Four sources for the unreliability of synaptic transmission have been investigated: (i) the fluctuation of axon thresholds at the site of stimulation causing the failure to generate a nerve impulse in the appropriate Schaffer collaterals, (ii) the failure of nerve impulses generated at the site of stimulation to arrive at the synapse because of conduction failures at axon branch points, (iii) an artifactual synaptic unreliability due to performing experiments in vitro at temperatures well below the normal mammalian body temperature, and (iv) transmission failures due to probabilistic release mechanisms at synapses with a very low capacity to release transmitter. We eliminate the first three causes as significant contributions and conclude that probabilistic release mechanisms at low capacity synapses are the main cause of unreliability of synaptic transmission. 相似文献
72.
Epiderrnolysis bullosa (EB), a heterogeneous group of rare, inherited disorders, is manifested by recurrent blistering of the skin induced by the slightest trauma. Little information exists regarding the nutrition management of patients with EB. This study presents information on growth, identifies potential nutrition problems, and provides guidelines for nutrition management of persons with EB. Eighty patients attending a dermatology clinic for EB patients are described. Severity of disease ranged from mild blistering of the knees, elbows, and feet to extensive blistering and scarring of the skin and entire gastrointestinal tract. Of the 18 children with EB simplex, which is a mild form of the disease, 4 (22%) were at nutritional risk. None of the 13 adults with EB simplex were underweight and 8 (62%) were overweight. Of the patients with the more severe forms of EB, 27 of the 35 (77%) children with dystrophic EB and 4 of the 7 (57%) children with junctional EB were at risk for malnutrition. Of the 7 adults with dystrophic EB, 6 (86%) were underweight. Common nutrition problems included protein-energy malnutrition, chewing and swallowing problems, constipation, anemia, and vitamin/mineral deficiencies. When nutrition care protocols address these problems, growth, development, and nutritional status can improve. For those with severe nutrition problems, gastrostomy feeding or similar nutrition therapies should be considered. J Am Diet Assoc. 1995; 95:575-579. 相似文献
73.
BACKGROUND: A simple, rapid, inexpensive method for measuring the flow in a
patient's vascular access would permit routine monitoring during
haemodialysis, and hence provide information of access graft deterioration
sufficiently early to increase the success of minimally invasive remedial
procedures. This paper reports the validation of such a method in animals.
METHODS: A PTFE graft was implanted in sheep between the carotid artery and
the jugular vein. While the sheep was under general anaesthesia and on an
haemodialysis circuit, ultrasound velocity in its blood was perturbed by
the injection of a 5-10 ml bolus of isotonic NaCl. The pump tubing flow was
measured by a transit-time blood flow meter. This flow was combined with
the areas of perturbation generated by the injection before and after
mixing in the access flow to estimate graft flow. The calculated graft flow
was compared to flow measured directly by a transit-time probe on the same
carotid artery. RESULTS: Over a 10-fold range, 120-1260 ml/min, graft flow
measured by ultrasound velocity dilution agreed well with graft flow
measured directly with a scatter of 76 ml/min about the regression line.
CONCLUSION: Ultrasound velocity dilution provides a method for measuring
flow in the graft accurate enough for clinical evaluation of patients on
dialysis.
相似文献
74.
75.
Pulmonary Function in Survivors of Wilms' Tumor 总被引:1,自引:0,他引:1
N. J. Shaw O. B. Eden M. E. M. Jenney R. F. Stevens P. H. Morris-Jones A. W. Craft L. Castillo 《Pediatric hematology and oncology》1991,8(2):131-137
The respiratory status of 47 patients surviving childhood Wilms' tumor was studied. The group that had receivedflnnk irradiation (which impinges on the lower lung) (n - 17) had a sisnijGantly lower mean percent predicted for forced expiratory volume in one second, residual volume, and total lung capaci(v when compared to those who had received no irradiation (n - 23). Those patients who had received whole-lung irradiation (n - 3) had sisnijicantly lower transfn. foctor for carbon monoxide and gas transfer per unit lung volume whm compared to the nonirradiated group (n - 23). There was no sipiftiant dimue in the prevalence of respiratory symptoms between the three groups. Patients receiving any form of radiotherapy for Wilms' tumor may have abnormulities o f pulmonary function and should have pulmonary function tests performed as part o f their long-tmn follow-up. 相似文献
76.
77.
S. Gururangan R. A. M. Lawson P. Morris Jones R. F. Stevens R. H. A. Campbell 《Pediatric hematology and oncology》1992,9(2):107-113
The role of open lung biopsy (OLB) in the diagnosis of the etiology of lung infiltrates in children was analyzed for a 10-year period 1979-1989 in a tertiary referral center. A total of 18 children had 19 lung biopsies to ascertain the cause of lung infiltrates. Thirteen of these children (72 %) were immunocompromised due to treatment of hematological/solid malignancies and bone marrow transplantation. The clinical diagnosis was bilateral lung infiltrates of unknown etiology in 17 of 18 children. Eight of these children were ventilated for respiratory failure. The biopsy was useful in achieving a histological diagnosis in 18 of 19 samples (diagnostic yield 95%) and an etiological diagnosis in 14 of 19 samples (etiological yield 74 %). Therapeutic strategy was altered in 14 of 18 patients based on the biopsy results. Five of 14 patients responded favorably to a change in specific treatment. The lime interval from onset of respiratory illness to biopsy was 2-60 days (mean 16 days). Despite the critical state of these children there were few complications associated with the biopsy and no mortality directly related to the procedure. We recommend that OLE be undertaken sooner rather than later in immunocompromised children with bilateral pulmonary infiltrates of unknown etiology. 相似文献
78.
79.
Ronald R. Watson PhD Mary E. Mohs MS RD Cteamond Eskelson PhD Richard E. Samptiner MD Barbara Hartmann PhD 《Alcoholism, clinical and experimental research》1986,10(4):364-385
The prevalence and incidence of heavy alcohol consumption are major problems which have been increasing in many countries in recent years. It is crucial for physicians to consistently identify early drinking problems as well as the various end disease states in order to minimize suffering and maximize recovery. This paper reviews the evolutionary development of clinical tools for detection of alcohol abuse. The focus is primarily on clinical/biochemical indicators of alcohol abuse, emphasizing but not limited to changes in hematological characteristics, liver enzyme activity, lipids, immune function factors, hormones, neurological factors, and some physically based tests. Use of test combinations and sophisticated statistical analysis of pattern changes in test batteries evidence increased diagnostic efficiency. 相似文献
80.
Acute myelocytic leukemia and prior allergies 总被引:1,自引:0,他引:1
R K Severson S Davis D B Thomas R G Stevens L Heuser L E Sever 《Journal of clinical epidemiology》1989,42(10):995-1001
The relationship between prior allergies and adult acute myelocytic leukemia was investigated in a population-based case-control study. Based on data from personal interviews of 98 cases and 133 controls, a history of any type of allergy was associated with a significantly decreased risk of acute myelocytic leukemia (OR = 0.35, 95% CI = 0.20-0.60). Risk declined with the total number of specific allergies reported (p less than 0.001), and was reduced in relation to a history of prior asthma, eczema and hives. The implications of these findings in relation to natural immune surveillance against developing neoplasms are discussed. 相似文献