全文获取类型
收费全文 | 37692篇 |
免费 | 3890篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 482篇 |
儿科学 | 1117篇 |
妇产科学 | 766篇 |
基础医学 | 5394篇 |
口腔科学 | 1447篇 |
临床医学 | 4287篇 |
内科学 | 7506篇 |
皮肤病学 | 450篇 |
神经病学 | 2955篇 |
特种医学 | 1413篇 |
外国民族医学 | 2篇 |
外科学 | 5013篇 |
综合类 | 956篇 |
一般理论 | 30篇 |
预防医学 | 3928篇 |
眼科学 | 1044篇 |
药学 | 2841篇 |
1篇 | |
中国医学 | 29篇 |
肿瘤学 | 1996篇 |
出版年
2021年 | 535篇 |
2020年 | 342篇 |
2019年 | 558篇 |
2018年 | 643篇 |
2017年 | 488篇 |
2016年 | 509篇 |
2015年 | 631篇 |
2014年 | 878篇 |
2013年 | 1304篇 |
2012年 | 1707篇 |
2011年 | 1782篇 |
2010年 | 1009篇 |
2009年 | 1004篇 |
2008年 | 1567篇 |
2007年 | 1686篇 |
2006年 | 1551篇 |
2005年 | 1600篇 |
2004年 | 1459篇 |
2003年 | 1388篇 |
2002年 | 1369篇 |
2001年 | 1103篇 |
2000年 | 1158篇 |
1999年 | 1087篇 |
1998年 | 475篇 |
1997年 | 393篇 |
1996年 | 450篇 |
1995年 | 391篇 |
1994年 | 400篇 |
1993年 | 364篇 |
1992年 | 867篇 |
1991年 | 856篇 |
1990年 | 873篇 |
1989年 | 800篇 |
1988年 | 756篇 |
1987年 | 757篇 |
1986年 | 713篇 |
1985年 | 725篇 |
1984年 | 536篇 |
1983年 | 491篇 |
1982年 | 320篇 |
1981年 | 328篇 |
1980年 | 300篇 |
1979年 | 474篇 |
1978年 | 382篇 |
1977年 | 310篇 |
1976年 | 294篇 |
1974年 | 374篇 |
1973年 | 362篇 |
1972年 | 297篇 |
1971年 | 311篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
53.
Using a simplified procedure, we have extracted DNA from unstained paraffin sections of needle biopsies of kidney and liver transplants and identified the presence of CMV using the polymerase chain reaction. This method utilizes oligonucleotide primers for two genes shown to be specific for cytomegalovirus (CMV) as well as an internal control gene (hemoglobin) in a single reaction. Utilizing nested PCR amplification with agarose gel electrophoresis, CMV can be detected without radioisotopes to a level of sensitivity equivalent to one one-hundredth of a cytomegalic virocyte per cm2 of a 3-microM paraffin section. This method is applicable to situations where only scarce paraffin-embedded tissue is available. 相似文献
54.
Maria-Carmen Wilson Jack . Greenberg Steven Barrer C. P. Shah 《Journal of neuroimaging》1992,2(3):156-158
Spinal cord infarction or ischemia predominates in the thoracic region, less so in the cervical and lumbar regions. Different etiological factors have been implicated in anterior spinal artery syndrome. Magnetic resonance imaging (MRI) allows in vivo imaging of spinal cord disease, including infarction. A 31-yearold, previously healthy man had an acute onset of interscapular pain, followed by rapid development of quadriparesis associated with paresthesias and mild bladder dysfunction. Initial MRI of the cervicothoracic region demonstrated normal findings. A repeat study obtained 6 days later showed marked increase in the cervical cord size, especially at the C6-7 level. On the T2-weighted sagittal series and after gadolinium injection, increased signal in the anterior portions of the cord extending from C-4 to the T2-3 interspace was noted. This was most prominent at the C-6 and C-7 levels. The coronal views revealed abnormal high signal in the region of the anterior horns of the gray matter, a finding that is recognized as an “owl's eyes” pattern. Because the MRI changes of cerebral infarction may succeed a clinical event by hours or days, accurate diagnosis may require delayed or repeated studies. This report suggests that the diagnosis of spinal cord disease requires a similar evaluation. 相似文献
55.
Ectoparasites infesting a population of urban gray squirrels (Sciurus carolinensis Gmelin) in northern Florida were collected monthly during 1974. Eleven species were identified: one flea (Orchopeas howardi (Baker], three suckling lice (Enderleinellus longiceps Kellogg & Ferris, Hoplopleura sciuricola Ferris, and Neohaematopinus sciuri Jancke), one tick (Dermacentor variabilis Say), two mesostigmatid (gamasid) mites (Androlaelaps casalis (Berlese) and A. fahrenholzi (Berlese], and four chiggers (Eutrombicula alfreddugesi (Oudemans), E. splendens (Ewing), Leptotrombidium peromysci Vercammen-Grandjean & Langston, and Parasecia gurneyi (Ewing]. The flea and three suckling lice represent core species of ectoparasites for the gray squirrel; the remainder are probably satellite species. Only E. longiceps varied significantly in prevalence or intensity of infestation among host age groups; subadult squirrels had higher intensities than adults. Peak prevalence of O. howardi occurred in January and attained maximum intensity in March, whereas both prevalance and intensity were minimum in August. Prevalence of H. sciuricola was maximum in November and remained at similar levels through June. It then declined significantly to its minimum in September-October. Intensity of infestation, however, was greatest in August, September, and January. Maximum prevalence of N. sciuri occurred from January to March and was minimum in September; intensity of infestation reached maxima in January, June, and August. 相似文献
56.
The bedside assessment of dysphagia may be difficult, due to the inability to witness the act of swallowing directly. The milk test described in this paper gives a good assessment of swallowing, is cheap and easily portable and allows an instant decision to be made without recourse to special investigations. 相似文献
57.
T G Wilson M J Hollands J M Little 《The Australian and New Zealand journal of surgery》1992,62(2):111-115
The treatment of chronic pancreatitis commonly yields disappointing results. Patients with chronic pancreatitis and a dilated pancreatic duct can be treated by longitudinal pancreaticojejunostomy. In order to evaluate the procedure, 20 patients undergoing pancreaticojejunostomy were followed for a median time of more than 5 years. Their clinical characteristics and outcomes have been compared with a group of 43 patients with chronic pancreatitis and small pancreatic ducts. There were no differences between the two groups in the major epidemiological parameters, except that calcification in the gland was more frequently noted in those with large ducts. The operation of longitudinal pancreaticojejunostomy could be accomplished with an acceptable morbidity. There was one death in the postoperative period. Seventy-six per cent of patients were found to have benefited clinically at five years, compared with 48% of those with small duct disease. This difference was statistically significant. Patients who benefited were defined by four factors; they were carrying out their usual occupation at the time of surgery, they were not narcotic dependent at the time of surgery, they had a pancreatic duct width greater than 7 mm and, they had totally abstained from alcohol from before the operation to the time of follow-up. Longitudinal pancreaticojejunostomy probably remains the best surgical treatment for suitable patients with chronic pancreatitis. The operation should only be performed when the pancreatic duct is greater than 7 mm in width. In such patients the operation produces considerable improvement of pain with minimal metabolic disturbance. 相似文献
58.
59.
Elevated levels of acute phase plasma proteins in major depression. 总被引:10,自引:0,他引:10
P R Joyce C R Hawes R T Mulder J D Sellman D A Wilson D R Boswell 《Neuropsychopharmacology》1992,32(11):1035-1041
Levels of acute phase and other plasma proteins were measured in 21 men with major depression, 28 men with alcohol dependence, and 12 men who acted as controls. The depressed men had significantly elevated levels of the acute phase proteins, haptoglobin and alpha-1-antichymotrypsin, and of immunoglobulin G. The elevations in haptoglobin and alpha-1-antichymotrypsin were highly correlated with each other, and were correlated with the severity of depression and negatively correlated with the thyroid stimulating hormone response to thyrotropin. The alcoholic men had elevated haptoglobin levels, but significantly decreased levels of immunoglobulin G. These findings provide further evidence for an inflammatory response during depression. 相似文献
60.
Richard B Scott Ralph Gregory Joanna Wilson Sarah Banks Anna Turner Simon Parkin Nir Giladi Carol Joint Tipu Aziz 《Movement disorders》2003,18(5):539-550
Primary dystonia is a disorder of movement for which no consistent pathophysiology has been identified; in the absence of evidence to the contrary, it is assumed to be cognitively benign. We have studied a clinically heterogeneous group of 14 patients with primary dystonia on a battery of neuropsychological tests. Despite well-preserved speed of information processing, language, spatial, memory and general intellectual skills relative to normal controls, we have identified a constellation of attentional-executive cognitive deficits on the Cambridge Neuropsychological Test Automated Battery (CANTAB). Specifically, patients demonstrated significant difficulties negotiating the extra-dimensional set-shifting phase of the IED task. The implications of these findings for the pathophysiology of primary dystonia are discussed. This is, to the best of our knowledge, the first report of a significant cognitive deficit in patients with primary dystonia. 相似文献