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   7598篇
  免费   313篇
  国内免费   33篇
耳鼻咽喉   50篇
儿科学   142篇
妇产科学   155篇
基础医学   861篇
口腔科学   175篇
临床医学   522篇
内科学   2001篇
皮肤病学   59篇
神经病学   614篇
特种医学   363篇
外科学   1371篇
综合类   28篇
一般理论   1篇
预防医学   223篇
眼科学   76篇
药学   500篇
中国医学   24篇
肿瘤学   779篇
  2023年   67篇
  2022年   113篇
  2021年   210篇
  2020年   98篇
  2019年   125篇
  2018年   139篇
  2017年   124篇
  2016年   130篇
  2015年   114篇
  2014年   171篇
  2013年   221篇
  2012年   365篇
  2011年   407篇
  2010年   208篇
  2009年   158篇
  2008年   334篇
  2007年   398篇
  2006年   342篇
  2005年   357篇
  2004年   326篇
  2003年   323篇
  2002年   390篇
  2001年   229篇
  2000年   262篇
  1999年   240篇
  1998年   143篇
  1997年   89篇
  1996年   79篇
  1995年   58篇
  1994年   55篇
  1993年   45篇
  1992年   153篇
  1991年   152篇
  1990年   144篇
  1989年   129篇
  1988年   124篇
  1987年   110篇
  1986年   106篇
  1985年   102篇
  1984年   63篇
  1983年   53篇
  1981年   31篇
  1980年   31篇
  1979年   58篇
  1975年   32篇
  1974年   27篇
  1973年   27篇
  1972年   37篇
  1969年   34篇
  1968年   28篇
排序方式: 共有7944条查询结果,搜索用时 31 毫秒
21.
The glomerular injuries in 129 cases of IgA nephropathy (IgA-N) were examined ultrastructurally with special reference to the glomerular basement membrane (GBM) deposits and capillary loop abnormalities, and the correlation between these findings and the clinicopathological data was analyzed. The following results were obtained. 1) The degree of daily excretion of urine protein (UP) and creatinine clearance (Ccr) revealed a significant correlation with the degree of mesangial hypercellularities and the frequency of segmental lesions. 2) All sites of GBM deposits, and discontinuity and/or splitting among the GBM abnormalities showed a significant relation to the severity of proliferation and segmental lesions. 3) The GBM deposits, discontinuity and splitting showed a significant relation to the degree of UP and Ccr. We speculate therefore that capillary loop deposits and/or capillary loop discontinuity and splitting could represent histological prognostic factors for an unfavorable outcome in IgA nephropathy.  相似文献   
22.
The mechanism by which prostacyclin acts to prevent in vivo reperfusion injury is still uncertain. This study was therefore undertaken to assess the effect of a stable prostacyclin analogue (OP 41483-alpha-CD [OP]) on oxygen-derived free radicals after heart-lung transplantation. OP was administered to the heart-lung graft through the pulmonary artery for 25 minutes encompassing the reperfusion process. Free radicals were directly measured by electron spin resonance spectroscopy. The radical intensities of pulmonary venous blood were significantly lower in the OP group than in the control group, suggesting that fewer free radicals were generated in the lungs of the OP group. The cardiac and respiratory function were better in the OP group than in the control group. The lung is the primary source of oxygen free radical attack, and the beneficial action of OP on free radical generation is almost exclusively restricted to the lung and does not apply to the heart. This result suggested that OP probably is effective in inhibiting free radical generation from the endothelium.  相似文献   
23.
A patient with cerebral deep sinus thrombosis, which was not diagnosed on the first examination, is reported. A 46-year-old woman presented with headache and vomiting. Neurological examination and a brain computed tomography (CT) scan showed no obvious abnormal findings. The patient suffered disturbed consciousness on the day after the examination, and was admitted to our emergency centre. A CT scan and magnetic resonance imaging revealed an ischaemic lesion in the left basal ganglia, suggesting deep sinus occlusion. Anticoagulant therapy was administered. One day after admission, a CT scan showed a haematoma and severe brain swelling in the same region. Cerebral angiography demonstrated a straight sinus occlusion. Intracranial pressure was not controlled with hypothermia, and the patient died 25 days after admission. Review of the initial CT scan revealed subtle, early findings of deep venous thrombosis that were missed on first examination.  相似文献   
24.
The aim of this study was to fabricate an artificial bile duct for the development of a new treatment for biliary diseases. Eighteen hybrid pigs were implanted with a bile duct organoid unit (BDOU) made of a bioabsorbable polymer. Twelve of the transplanted BDOUs had been seeded with autologous bone marrow cells (BMCs) in advance. Six animals, the controls, were grafted with the scaffold alone with no BMCs seeded. The common bile duct was cut, the hepatic cut end of the native common bile duct was anastomosed to the BDOU and the other end was anastomosed to the duodenum. The controls underwent a similar operation. The neo-bile duct was removed at pre-determined time points and investigated histologically. All 18 recipient pigs survived until their sacrifice at 6 weeks, 10 weeks or 6 months. Histological examination revealed incomplete epithelialization of the neo-bile duct at 6 weeks and 10 weeks after transplantation. At 6 months, the organoid exhibited a morphology almost identical to that of the native common bile duct. No differences were found between the controls and BMC-seeded pigs. These results show that the artificial bile duct thus fabricated can serve as a substitute for the native bile duct.  相似文献   
25.
Effects of cueing on visuospatial processing in unilateral spatial neglect   总被引:2,自引:0,他引:2  
Patients with typical left unilateral spatial neglect bisected lines after cueing to the left end-point, the fixation point being monitored with an eye camera. They persisted with the point of initial fixation made after cueing and placed the mark there without searching leftwards again. The rightward shift of fixation to the initial point of fixation thus determined the location of the subjective midpoint. We consider that rightward attentional bias increased the amplitude of this shift that was planned on the basis of the perception of the whole line while cueing. This hypothesis may explain smaller but obvious rightward bisection errors found in the cueing condition.  相似文献   
26.
We report herein the case of a 70-year-old man in whom a chest wall implantation of adenocarcinoma of the lung at the drainage tube site was found 4 months after a right lower lobectomy with mediastinal lymph node dissection had been performed for adenocarcinoma of the right lower lobe. The lesion was successfully treated by tumor extirpation. We believe that tumor seeding to the chest wall occurred at the time of thoracotomy. To prevent such tumor seeding, the pleural cavity should be washed out routinely with a massive volume of physiological saline solution prior to closure of the chest wall.  相似文献   
27.
During last year, 931 men aged 51.0 +/- 9.5 years participated in our hospital's 3-day health screening. Their axillary temperature were taken 3 times per day (twice each, at 6:00 a.m., 2:00 p.m. and 6:00 p.m.) during their 3-day stay and the mean axillary temperature was determined for each subject. In 72 among all subjects, the mean axillary temperature was below 36 degrees C. These 72 subjects were classified as low-temperature individuals with normal temperature below 36 degrees C. This study was designed to compare low-temperature subjects with mean axillary temperature, on various factors, such as age, degree of obesity, liver function, renal function, lipids, electrolytes, and biochemical data (blood glucose, serum amylase, and CPK). This study also included seasonal changes in these low-temperature subjects. The following results were obtained. 1) Age was most closely related to low-axillary temperature, and the degree of obesity (modified Broca-Katsura method) had second significant relation. The low-axillary temperature was in common in subjects over 60 years and was also common in obese subjects, regardless of their age. 2) No seasonal effect was observed with low-temperature subjects. 3) Only the age and the degree of obesity (modified Broca-Katsura method) showed negative correlation independently with the mean axillary temperature. (For age, the correlation coefficient was Y = -0.006539X + 36.491, while for obesity it was Y = -0.004536X + 36.203.) Therefore the older and the more obese the subjects, the lower the mean axillary temperature.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
28.
We studied the clinico-pathological correlation of collagen disease-related pulmonary lesions to examine the pathological and radiological features of collagen lung, and the effect of steroid therapy. Ten open lung biopsy cases were examined; 4 male, and 6 female. The mean age was 55 years old. Seven cases developed pulmonary shadows after the diagnosis of collagen disease, and 3 cases showed pulmonary shadow prior to diagnosis. Pathologically, 6 cases proved to be bronchiolitis obliterans organizing pneumonia (BOOP), 3 cases were chronic interstitial pneumonia (UIP), and 1 case was acute interstitial pneumonia. All cases had inflammatory thickening of the interstitium involving the pleura, bronchial wall, and perivascular connective tissue. Half of the cases had bronchiolar inflammatory lesions. Radiologically BOOP cases showed either localized ground glass shadows, or diffuse reticulonodular shadows predominantly in the lower lung fields with shrinkage of affected areas. UIP cases showed reticulonodular shadows, and active UIP cases showed overlapping ground glass shadows. Steroids were administered in cases of BOOP and active UIP, and all cases showed improvement. We consider that open lung biopsy is of use in the diagnosis of some cases and in assessing whether steroid therapy is indicated.  相似文献   
29.
The blocking effects of complement-dependent sperm immobilizingantibodies in the sera of infertile women and monoclonal antispermantibodies against humans and mice on fertilization were investigated.The hemizona assay (HZA) and sperm penetration assay (SPA) wereused to study the inhibitory effects of sera from 22 infertilepatients positive for sperm immobilizing antibodies. Use ofthese tests allowed us to differentiate whether the antibodyblocked sperm—zona pellucida tight binding and/or spermpenetration into the ooplasm. The zona pellucida penetrationassay (ZPA) was also used to study the effects of four monoclonalantibodies (mAbs) on human sperm penetration into the zona pellucida.Seven mAbs against murine spermatozoa were tested for theirinhibitory effects on in-vitro fertilization (IVF) and HZA inmice. Of 22 patient sera with sperm immobilizing antibodies,21 (95.5%) inhibited HZA attachment and penetration, whereasthis did not occur in any of 13 patient sera without these antibodies.However, 19 of 22 (86.4%) patient sera with sperm immobilizingantibodies and eight of 13 (61.5%) patient sera without theseantibodies inhibited the SPA. Two (2C6, 1G12) of four mAbs againsthuman spermatozoa showed strong inhibitory effects in all theassays (HZA, ZPA and SPA). One mAb (3B10) did not inhibit HZAbut blocked ZPA and SPA. Another mAb (H6-3C4) seemed to haveno inhibitory effects on fertilization. Two (Vx 5 and Vx 8)of seven mAbs against murine spermatozoa inhibited IVF in micebut did not block mouse HZA. These findings suggest that antispermantibodies block fertilization at specific stages. Some of themmay inhibit sperm capacitation and thus prevent all processesof fertilization that follow. Some other antibodies may notaffect capacitation and sperm binding to zona pellucida butinhibit the acrosome reaction, followed by the blocking of spermpenetration through zona pellucida and ooplasm.  相似文献   
30.
Clinical significance of reverse redistribution on thallium image was evaluated in 54 patients who had undergone PTCA. Thallium SPECT imaging was performed one week and three to six months after PTCA. Reverse redistribution was detected eight of 54 patients one week after PTCA and five of 38 patients three to six months after PTCA. In the segments with reverse redistribution, reduced regional wall motion and lesser degree of coronary stenosis was common features (p less than 0.05) angiography. In conclusion, reverse redistribution had a tendency to appear in the region with mild myocardial injury and relatively high coronary blood flow after PTCA. But in cases with new occurrence and disappearance of reverse redistribution during follow up period, we can not assess the factors to explain these phenomena. In these segments, "coronary flow reserve", "stunned myocardium", "hibernating myocardium" or other factors may be related.  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