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   46600篇
  免费   4152篇
  国内免费   52篇
耳鼻咽喉   530篇
儿科学   1338篇
妇产科学   1066篇
基础医学   6023篇
口腔科学   1081篇
临床医学   5356篇
内科学   8818篇
皮肤病学   725篇
神经病学   4922篇
特种医学   2111篇
外国民族医学   5篇
外科学   6366篇
综合类   789篇
一般理论   34篇
预防医学   4434篇
眼科学   1180篇
药学   3154篇
  2篇
中国医学   54篇
肿瘤学   2816篇
  2021年   584篇
  2019年   557篇
  2018年   646篇
  2017年   564篇
  2016年   567篇
  2015年   669篇
  2014年   878篇
  2013年   1417篇
  2012年   1951篇
  2011年   2062篇
  2010年   1163篇
  2009年   1056篇
  2008年   1847篇
  2007年   2051篇
  2006年   1944篇
  2005年   1839篇
  2004年   1818篇
  2003年   1675篇
  2002年   1707篇
  2001年   1528篇
  2000年   1555篇
  1999年   1381篇
  1998年   575篇
  1997年   555篇
  1996年   525篇
  1995年   494篇
  1994年   435篇
  1993年   379篇
  1992年   1161篇
  1991年   1174篇
  1990年   1106篇
  1989年   1098篇
  1988年   922篇
  1987年   1048篇
  1986年   970篇
  1985年   966篇
  1984年   762篇
  1983年   623篇
  1982年   410篇
  1981年   367篇
  1980年   377篇
  1979年   703篇
  1978年   526篇
  1977年   449篇
  1976年   461篇
  1975年   395篇
  1974年   520篇
  1973年   456篇
  1972年   383篇
  1971年   364篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Depression is common in Parkinson's disease (PD) and affects 30 to 50% of all patients. In contrast to the wealth of research on depression in PD, little is known about the occurrence of depression in other movement disorders. The primary objective of the current study was to determine whether the high prevalence of depression symptoms seen in PD is also found in other movement disorders, by directly comparing rates of specific depression symptoms and depression severity across PD, dystonia, and essential tremor (ET). Three hundred and fifty-four patients with PD, 83 patients with dystonia, and 53 patients with ET completed the Beck Depression Inventory (BDI). We found no significant between-groups differences for depression severity, frequency, or endorsement of specific depression symptoms. Forty-eight percent of PD patients, 37.3% of dystonia patients, and 34% of ET patients were found to be at least mildly depressed (BDI score of 10 or higher). The most commonly endorsed symptoms were fatigability, difficulty with work, anhedonia, and sleep disturbance. Clinicians should be aware that depression is a frequent problem in dystonia and ET, in addition to PD, and inquire about depression symptoms in these patients so that they can be appropriately treated.  相似文献   
93.
PURPOSE: To examine the application of statistical parametric mapping (SPM) to analyze ictal single-photon emission computed tomography (SPECT) scans in surgical candidates with extratemporal lobe epilepsy. METHODS: The authors selected patients who underwent successful ictal SPECT acquisition in the process of surgical treatment of intractable partial epilepsy. Thirteen patients were identified who met inclusion criteria for confident seizure localization from either intracranial electroencephalogram recordings or epilepsy surgery outcome. In these cases, ictal scans were registered to an in-house-developed normal SPECT atlas composed of 14 spatially normalized brains of normal subjects. SPM96 was used to test on a voxel-by-voxel basis for statistically significant increases in blood flow associated with each patient's ictal scan. The results were then mapped back onto the patient's magnetic resonance image (MRI) for final interpretation. Statistical parametric mapping (SPM) analysis of ictal SPECT scans was compared to both conventional visual interpretation and the analysis of subtraction ictal SPECT co-registered to MRI (SISCOM). RESULTS: Ten of 13 patient scans showed localizing focal ictal increases in regional cerebral blood flow, all of which were concordant with ultimate epilepsy localization. Of the 3 cases not localized with SPM, 1 was localized by conventional visual interpretation and another, not localized by visual interpretation, was correctly localized with SISCOM. Two cases not localized by SISCOM were localized by both visual and SPM analysis. CONCLUSIONS: This work provides supportive evidence for proof of principle that SPM can be used to provide objective, accurate analysis of ictal SPECT scans in patients with extratemporal lobe epilepsy.  相似文献   
94.
BACKGROUND AND OBJECTIVES: To determine differences in the amount of work involved in caring for functionally monocular patients who undergo cataract surgery compared with binocularly sighted patients. PATIENTS AND METHODS: This was a retrospective study that included 100 consecutive functionally monocular patients and 100 binocularly sighted control patients matched by age (+/-5 years) and date of surgery ( +/-1 year). Office records were reviewed to determine several measures of office and operating room work effort. RESULTS: There was no difference between groups in preoperative telephone calls (P = .136), postoperative telephone calls (P = .580), preoperative office visits (P = .875), postoperative office visits (P = .601), or the number of times surgery was scheduled (P = 1.00). Monocular patients required more time for surgery (37.4 minutes) than binocular patients (32.4 minutes) (P= .010). CONCLUSIONS: It takes longer to perform cataract surgery on functionally monocular patients than on binocularly sighted patients.  相似文献   
95.
B M Bowman  S C Miller 《BONE》1986,7(5):351-357
The purpose of this study was to determine the capacity of the bone-lining cell, which covers most nonremodeling bone surfaces in the adult skeleton, to proliferate and contribute to the rapid endosteal osteogenic response following estrogen treatment in male Japanese quail. In control, untreated birds bone-lining cells cover most of the femoral endosteal surface. Bone-lining cells are thinly extended along bone surfaces, have flat nuclei, and account for about 77% of the cells adjacent to the bone surface. The lineal density of bone surface cells in the controls was about 21 cells/mm of bone surface. By 16-20 h after estrogen administration cells with larger, round nuclei were seen on the bone surface and some of these cells contained a 3H-thymidine (3H-TdR) label. Within the first 24 h after estrogen administration the lineal bone surface cell density had increased to about 38 cells/mm. At 20-30 h after estrogen administration, most of the cells adjacent to the bone surface were round. The peak 3H-TdR labeling of cells immediately adjacent to the bone surface occurred about 36 h after estrogen administration. By 48 h the bone surface was covered with osteogenic cells and developing medullary bone. These results suggest that the bone-lining cell in the adult appears to retain some proliferative capability and osteogenic potential. However, because a rapid increase in cell density began prior to the rapid increases in 3H-TdR labeling, as well as the appearance of mitotic figures on the bone surface, another source of cells may have also contributed to the osteogenic response induced by estrogen.  相似文献   
96.
97.
Diagnosis of Crohn's disease in children may be delayed because of obscure presentation and inappropriate investigation. The clinical and radiological features in 35 children with Crohn's disease were reviewed retrospectively. The distal ileum and proximal colon were the most common sites of disease. Intestinal symptoms and signs were often overshadowed by nonspecific complaints. Proximal small bowel disease was characterised by oedema, clubbing, anaemia, and stunting of growth. The delay in diagnosis was less than in other series, although most prolonged in the group with proximal disease. We have identified a group of clinical features that strongly suggests Crohn's disease. In these patients, we believe a small bowel enema is justified. Small bowel enema, although invasive, is more effective than barium meal and follow-through for demonstrating Crohn's disease. Severity of radiological changes did not correlate with clinical assessment. Neither bowel stricture nor fistula was found. Radiology of the colon was insensitive and colonoscopy is better for assessing colonic disease.  相似文献   
98.
Mice were treated with ketoconazole with and without dimethyl sulfoxide. Concentrations of ketoconazole at 3 and 5 h after treatment were significantly higher in serum (P less than 0.05) and brain tissue homogenate (P less than 0.01) of mice treated with dimethyl sulfoxide than in those of mice not treated with dimethyl sulfoxide.  相似文献   
99.
Prednisone-induced worsening of neuromuscular function in myasthenia gravis   总被引:2,自引:0,他引:2  
In patients with myasthenia gravis who received single doses of prednisone orally (40 to 100 mg), we found acute inhibition of neuromuscular function as manifest by increased decremental responses to repetitive nerve stimulation, reduced twitch tension, and lowered maximum voluntary contraction strength. The time course of these changes correlated with plasma methylprednisolone levels, implying direct drug effects on neuromuscular function.  相似文献   
100.
Image filtering with the larger, and potentially most valuable, digital filters is very time-consuming, thus precluding use of these filters in routine clinical applications. A recently developed algorithm for spatial-domain filtering is described, and its speed is compared with those of conventional methods with and without an array processor. Using the new Chebyshev method, a 64 by 64 pixel image can be filtered on a standard 16-bit minicomputer with filters of size 3 by 3 to 23 by 23 in 1.4-9.2 sec. The conventional spatial-domain algorithm requires 3.8-71 sec. With an array processor, filtering is accomplished in 0.19-0.54 sec. Filtering in the frequency domain requires 34 sec without an array processor and 0.12 sec with one. Thus with this new Chebyshev algorithm, clinically practical digital filtering can be performed with large filters even without an array processor.  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