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   4645篇
  免费   436篇
  国内免费   31篇
耳鼻咽喉   61篇
儿科学   203篇
妇产科学   61篇
基础医学   713篇
口腔科学   119篇
临床医学   493篇
内科学   986篇
皮肤病学   102篇
神经病学   239篇
特种医学   353篇
外科学   727篇
综合类   55篇
一般理论   1篇
预防医学   309篇
眼科学   98篇
药学   321篇
中国医学   2篇
肿瘤学   269篇
  2023年   29篇
  2022年   29篇
  2021年   48篇
  2020年   49篇
  2019年   45篇
  2018年   113篇
  2017年   92篇
  2016年   96篇
  2015年   132篇
  2014年   142篇
  2013年   206篇
  2012年   170篇
  2011年   164篇
  2010年   159篇
  2009年   188篇
  2008年   169篇
  2007年   163篇
  2006年   176篇
  2005年   135篇
  2004年   149篇
  2003年   128篇
  2002年   129篇
  2001年   114篇
  2000年   124篇
  1999年   119篇
  1998年   140篇
  1997年   112篇
  1996年   132篇
  1995年   92篇
  1994年   105篇
  1993年   66篇
  1992年   82篇
  1991年   96篇
  1990年   67篇
  1989年   90篇
  1988年   86篇
  1987年   82篇
  1986年   76篇
  1985年   71篇
  1984年   63篇
  1983年   46篇
  1982年   38篇
  1980年   42篇
  1979年   39篇
  1978年   33篇
  1977年   29篇
  1976年   36篇
  1975年   34篇
  1974年   37篇
  1973年   28篇
排序方式: 共有5112条查询结果,搜索用时 0 毫秒
21.
beta/A4, a peptide that forms the extracellular amyloid fibrils of Alzheimer senile plaques, has also been proposed to be a component of Alzheimer paired helical filaments (PHFs). We compared BR88, an antiserum to amino acids 1-12 of beta/A4, with BR126, an antiserum to the sequence SEKLDFKDRVQS in tau protein, since tau protein is the only confirmed component of PHFs. In enzyme-linked immunosorbent assays (ELISAs), both antibodies reacted with pronase-treated PHFs better after PHFs were treated with guanidine. tau protein shares no sequence homology with beta/A4. Nevertheless, BR88 cross-reacted with human recombinant tau isoforms by ELISA and Western blot analysis with potencies comparable to those for anti-tau antibodies. BR88 reacted with a beta/A4 peptide as well on a molar basis as with tau protein and showed some reactivity to the tubulin-binding region of tau protein. In conclusion, the beta/A4 antiserum BR88 cross-reacts with tau protein, possibly explaining its reactivity with PHFs.  相似文献   
22.
23.
OBJECTIVE: Although cutaneous leishmaniasis (CL) occurs mostly in the facial area, periocular involvement accounts for 2-5% of the facial lesions. CL lesions localized in the periocular region can easily be confused with various other diseases. The aim of this study was to examine the frequency of periocular involvement in CL in the Cukurova region of Turkey, as well as the clinical characteristics, diagnosis and methods of treatment of this disease. METHODS: Between December 1998 and December 2004, patients who were diagnosed with CL were evaluated prospectively with respect to periocular involvement. RESULTS: From the 2066 patients evaluated with CL, 2622 lesions were identified. In 59 (2.9%) of these patients, a total of 66 (2.5%) lesions were located in the periocular area. Thirty-two (48.5%) of these lesions were of the papular type, 15 (22.7%) the nodulo-ulcerative type, 10 (15.2%) the plaque type, and nine (13.6%) the nodular type. Dacryocystitis was identified in four patients with periocular involvement. Over the follow-up period, no ocular or periocular deformities or complications developed in these patients. CONCLUSION: Patients suspected of CL should be evaluated and treated early in the course of their disease to prevent any permanent ocular or periocular deformities.  相似文献   
24.
25.
Zolmitriptan (ZomigTM) is a 5HT1B/1D agonist which has the ability to cross the intact blood-brain barrier to access central as well as peripheral receptors. Because of the potential for central nervous system side effects, this randomized, double-blind, placebo-controlled, 6-period crossover study evaluated the effects of 2.5 and 5 mg doses of zolmitriptan on psychomotor performance and investigated any pharmacodynamic or pharmacokinetic interaction with diazepam. Twelve healthy volunteers received the following "treatments" as single doses: zolmitriptan 2.5 mg, zolmitriptan 5 mg, diazepam 10 mg, zolmitriptan 2.5 mg+diazepam 10 mg, zolmitriptan 5 mg+diazepam 10 mg and placebo. Pre-dose and at 1, 4, 8, and 24 h post-dose, the following validated battery of psychomotor tests was performed: Bond-Lader visual analogue scales (calmness, contentedness, and alertness factors), critical flicker fusion test, choice reaction time (recognition, motor, and total reaction times), finger-tapping test, number cancellation test and digit symbol substitution test. Plasma concentrations of zolmitriptan, its active metabolite, and diazepam and its active metabolites were measured at the same timepoints. Zolmitriptan 2.5 and 5 mg had no effect on psychomotor function when given alone. In contrast, diazepam 10 mg had profound effects, consistent with its sedative properties, but there was no synergism on concomitant administration of either dose of zolmitriptan. Plasma concentrations of zolmitriptan, diazepam, and their respective active metabolites were similar when the two drugs were given alone or in combination.  相似文献   
26.
We investigated non-rapid eye movement (non-REM) sleep in patients with newly diagnosed Parkinson's disease (PD) who had never previously received dopaminergic medication. There were no significant differences in the conventional sleep parameters between de novo patients with PD and a healthy control group, but the length of stage 1 sleep and the number of awakenings increased significantly upon administration of dopaminergic drugs. Analyzing the quantitative electroencephalogram (EEG), we observed a significant reduction in the low-delta frequency range and a nonsignificant increase in the sigma frequency range in de novo patients with PD. The dopaminergic medication also nonsignificantly reduced the low-delta and sigma frequencies, the latter to the level of the controls. Possible mechanisms that may account for the observed differences are discussed. It is suggested that Parkinson's disease as well as the application of dopaminergic drugs exerts a desynchronizing effect on the sleep EEG that is reflected in a disruption of sleep continuity.  相似文献   
27.
Structural tensile properties analyses of 10-mm-wide central sections of quadriceps tendon-bone (QT-B) and bone-patellar ligament (B-PL) complexes from young male donors (mean age 24.9 years, range 19–32 years) were complemented by a cryosectional analysis: each QT-B complex was composed of the segment of the quadriceps tendon with the proximal half of the patella attached, each B-PL complex was composed of the distal half of the patella with the patellar ligament attached. A servohydraulic materials testing machine was used to assess ultimate failure load of 16 unconditioned and 16 preconditioned QT-B and B-PL complexes at an extension rate of 1 mm/s. Ligaments/tendons were preconditioned during 200 cycles from 50 to 800 N at 0.5 Hz. On cryosections the quadriceps tendons were significantly longer and thicker and exhibited a significantly larger bony attachment area than the patellar ligaments. Cross-sectional areas of 10-mm-wide, full-thickness, central parts of unconditioned quadriceps tendons were significantly greater and measured 64.6±8.4 mm2 with respect to the cross-sectional area of patellar ligament, measuring 36.8±5.7 mm2 (P<0.0025). Ultimate failure loads for unconditioned complexes resulted at 2173±618 N for QT-B complexes and at 1953±325 N for B-PL complexes (P=0.43). Ultimate failure load values measured 2353±495 N for preconditioned QT-B complexes and 2376±152 N for preconditioned B-PL complexes, respectively (P=0.77). Despite the fact that initial testing length, area of unconditioned QT-B and B-PL complexes were significantly different, displacement at ultimate load, energy to failure and total energy were not. In terms of ultimate tensile strength, the 10-mm-wide central part of the QT-B complex compared favourably to the tensile properties of the human femur-anterior cruciate ligament-tibia complex from a comparable young age group. The evidence from anatomic, cryosectional and structural properties analyses suggests that the QT-B complex may be a valuable and versatile adjunct to the surgeon's armamentarium in reconstructive cruciate ligament surgery.  相似文献   
28.
Special status of lateral clavicular fracture]   总被引:1,自引:0,他引:1  
Fractures of the lateral clavicle have different biomechanical conditions compared with fractures of the medial and central third; they therefore demand different therapy. Some 237 patients with fractures of the clavicle were followed, of which 75 (33%) were located in the lateral third of the clavicle. At the 5-year follow-up after exclusively conservative treatment, good results were found for Neer types I and III and 3 J?ger/Breitner type IIb fractures, while 4 out of 13 J?ger/Breitner type II a fractures ended in pseudarthroses (31%). Conservative treatment is recommended for Neer types I and III, as well as for the more stable J?ger/Breitner type II b and old II a fractures. Therefore, a new bandage is presented. It prevents the posterior and upward dislocation of the proximal fragment by vertical compression and rotation of the distal fragment by fixation of the arm. Open reduction and internal fixation by preferably extraarticular implants is recommended for unstable and dislocated J?ger/Breitner type II a fractures. For fractures of the lateral clavicle, good results can be achieved when the instability is recognized and adequately treated.  相似文献   
29.
Although a great number of psychometric tests and rating scales for the assessment of psychogeriatric patients is available, there is still an urgent need, in research and practice, for a clinical rating instrument that meets the following main requirements: (1) applicable to institutionalized and community patients and covering a wide range of behavioral pathology; (2) acceptable and easy to use for professionals and lay persons alike; (3) covering a wide range of behavior relevant to daily functioning but independent of sex or social status of the individual assessed. The NOSGER contains 30 items of behavior, each rated on a 5-point scale according to frequency of occurrence. Item scores are summarized into 6 Dimension scores (memory, instrumental activities of daily life, self-care, mood, social behavior, and disturbing behavior) which are clinically relevant in dementia, depression, and other psychiatric disorders of old age. Validation studies with a preliminary version of the NOSGER indicated good acceptance of the scale, high inter-rater and test-retest reliability, and high correlations of all NOSGER Dimension scores with results of a variety of established assessment instruments. The NOSGER is currently being used in a number of European and North American centers and should turn out to be a useful instrument for longitudinal studies in psychogeriatrics.  相似文献   
30.
Penetrating proximity extremity trauma (PPET) was prospectively studied to clarify the role of routine arteriographic evaluation (AG). Over a 24-month period, 135 patients were identified with 152 injuries from PPET. All patients underwent AG and were randomized to either immediate or delayed timing. There were 27 arteriographic abnormalities from these 152 wounds, of which 16 (10.5%) were in major arteries. One acute arteriovenous fistula underwent immediate surgery. The remaining 15 major vessel injuries were nonoperatively observed, including seven cases of segmental arterial narrowing, six intimal flaps, and two small pseudoaneurysms (one of which enlarged and underwent surgical repair after 10 weeks of followup). Nine of the remaining 14 lesions resolved; two improved and three remained clinically unchanged over a mean followup interval of 2.7 months. Shotgun trauma was the mechanism which carried the greatest risk of significant vascular injury. Although "soft" clinical signs were significantly more predictive of vascular injury following PPET than proximity alone (p less than 0.0005), 50% of all injuries to major arteries did not manifest soft signs. No extremity morbidity resulted from delayed AG or from vascular injury management. We conclude from our study population: 1) the natural history of clinically occult arterial injuries was predominantly benign; 2) AG could be safely delayed up to 24 hours; 3) "soft" signs were not clinically useful predictors of vascular injury; and 4) with the exception of shotgun wounds, AG did not appear to be a cost effective screening modality, since detection of a single vascular injury requiring surgery cost $66,420.00.  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