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   1654篇
  免费   100篇
  国内免费   10篇
耳鼻咽喉   13篇
儿科学   119篇
妇产科学   45篇
基础医学   185篇
口腔科学   41篇
临床医学   148篇
内科学   400篇
皮肤病学   43篇
神经病学   114篇
特种医学   58篇
外科学   220篇
综合类   13篇
预防医学   134篇
眼科学   34篇
药学   82篇
中国医学   1篇
肿瘤学   114篇
  2023年   18篇
  2022年   49篇
  2021年   68篇
  2020年   39篇
  2019年   46篇
  2018年   45篇
  2017年   37篇
  2016年   46篇
  2015年   47篇
  2014年   60篇
  2013年   93篇
  2012年   112篇
  2011年   143篇
  2010年   71篇
  2009年   64篇
  2008年   108篇
  2007年   100篇
  2006年   103篇
  2005年   104篇
  2004年   75篇
  2003年   60篇
  2002年   78篇
  2001年   29篇
  2000年   33篇
  1999年   34篇
  1998年   13篇
  1997年   12篇
  1996年   7篇
  1995年   11篇
  1994年   3篇
  1993年   1篇
  1992年   3篇
  1991年   3篇
  1990年   5篇
  1989年   4篇
  1988年   3篇
  1987年   6篇
  1986年   4篇
  1985年   2篇
  1984年   11篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
  1972年   2篇
  1938年   1篇
排序方式: 共有1764条查询结果,搜索用时 15 毫秒
101.
102.
The aim of this study was the immunolocalization of transitional cell carcinoma of the bladder with a radiolabelled murine tumour-associated monoclonal antibody and the measurement of the absolute uptake of the antibody by the tumour. Fourteen patients with transitional cell carcinoma of the bladder received 3–6 mCi (111–222 MBq) of technetium-99m labelled HMFG1 monoclonal antibody intravesically and one patient, 2 mCi (74 MBq) of iodine-131 labelled 11.4.1, which is a non-tumour-specific monoclonal antibody. Four of the 15 patients were evaluated with singlephoton emission tomography (SPET) 1 1/2 to 2 h post administration. All patients underwent transurethral resection of the bladder tumour within 12–20 h following intravesical administration of the radiolabelled antibody. The radioactivity of biopsy specimens from normal urothelium and tumour areas were counted in a gamma counter. The mean uptake of the radiolabelled antibodies from normal and tumour sites was expressed as a percentage of the administered dose per kilogram of tissue. Conventional histology and immunohistochemistry using HMFGI monoclonal antibody were performed on paraffin sections of the biopsy specimens. Although our results are preliminary, it can be concluded that: (a) bladder tumours are well imaged by SPET when using99mTc-HMFG1; (b) intravesically administered radiolabelled antibody remains on the bladder tissue and does not escape into the systemic circulation; (c) the wide range of tumour uptake values (0%–9.3% administered dose/kg) observed probably can be attributed to heterogeneity of the antigenic expression of the tumour; (d) values of99mTc-HMFGI monoclonal antibody uptake by the tumour do not justify future attempts at radioimmunotherapy.  相似文献   
103.
New bronchopulmonary dysplasia (BPD) has been suggested to be a maldevelopment sequence with reduced alveolarisation of the lungs; affected infants then would be predicted to have low lung volumes. The aim of this study was to test that hypothesis by comparing the lung volumes of infants who had had mild-moderate BPD with those without BPD of similar postmenstrual age. Lung volumes of 17 infants who had mild-moderate BPD (oxygen dependent beyond 28 days, but not past term) (BPD infants) were compared to those of 17 infants without BPD (non-BPD infants). All were born at less than 33 weeks of gestation and studied at postmenstrual ages of 33 to 39 weeks. Lung volume was assessed by measurement of functional residual capacity (FRC). The BPD infants had lower lung volumes (median 19.1 ml/kg) than the non-BPD infants (median 26.5 ml/kg) (p=0.0001). The BPD compared to the non-BPD infants were of greater postnatal age (p=0.0003), born at a lower gestational age (p=0.0001) and of lighter birthweight (p=0.0001). Regression analysis, however, demonstrated that lung volume was significantly related to BPD status (p=0.005), independently of postnatal age, birthweight and gestational age. It is concluded that the lower lung volumes of the infants who had had mild-moderate BPD support the hypothesis that new BPD is associated with poor alveolarisation.  相似文献   
104.
OBJECTIVES: To estimate the usefulness of serum tumor markers' monitoring, as predictors of gastric cancer in patients with pernicious anemia. PATIENTS AND METHODS: We investigated serum levels of carcinoembryonic antigen (CEA), alpha-fetal protein, cancer antigen (CA)-19.9, CA-125 and CA-15.3 in 50 patients with pernicious anemia and in 24 healthy controls, matched for age and sex. In 38 patients, the evaluation was repeated 1-6 months after the correction of cobalamin deficiency. RESULTS: All patients and controls had normal serum CEA and alpha-FP, and the levels of these markers as well as those of CA-125 and CA-19.9 did not differ between the two groups. All 50 patients, but only 2 controls exhibited increased serum CA-15.3, and the difference between the two groups was very significant (129.4 +/- 84.9 vs. 19.8 +/- 7.3 IU/ml, p < 0.001), while no difference between males and females was found. A thorough clinical examination of all patients, and mammographic study in 18 females did not reveal any finding suspicious of breast cancer. CA-15.3 levels were positively correlated with serum lactate dehydrogenase, and negatively with B(12) and hemoglobin, but they were substantially decreased after the correction of anemia, in all 38 patients tested, and in 33 of them they were restored to normal. After a median follow-up of 34 months, one patient developed a colon cancer, but none showed any sign suspicious of breast cancer. CONCLUSIONS: Serum CA-15.3 shows an aberrant increase in untreated patients with pernicious anemia, which is reversed after the correction of the anemia. The possible origin seems unrelated to mammary tissue, and may be released by the apoptosing bone marrow megaloblastic erythroblasts.  相似文献   
105.
106.
Abnormal Ca(2+) cycling in the failing heart might be corrected by enhancing the activity of the cardiac Ca(2+) pump, the sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) isoform. This can be obtained by increasing the pump's affinity for Ca(2+) by suppressing phospholamban (PLB) activity, the in vivo inhibitor of SERCA2a. In SKO mice, gene-targeted replacement of SERCA2a by SERCA2b, a pump with a higher Ca(2+) affinity, results in cardiac hypertrophy and dysfunction. The stronger PLB inhibition on cardiac morphology and performance observed in SKO was investigated here in DKO mice, which were obtained by crossing SKO with PLB(-/-) mice. The affinity for Ca(2+) of SERCA2 was found to be further increased in these DKO mice. Relative to wild-type and SKO mice, DKO mice were much less spontaneously active and showed a reduced life span. The DKO mice also displayed a severe cardiac phenotype characterized by a more pronounced concentric hypertrophy, diastolic dysfunction and increased ventricular stiffness. Strikingly, beta-adrenergic or forced exercise stress induced acute heart failure and death in DKO mice. Therefore, the increased PLB inhibition represents a compensation for the imposed high Ca(2+)-affinity of SERCA2b in the SKO heart. Limiting SERCA2's affinity for Ca(2+) is physiologically important for normal cardiac function. An improved Ca(2+) transport in the sarcoplasmic reticulum may correct Ca(2+) mishandling in heart failure, but a SERCA pump with a much higher Ca(2+) affinity may be detrimental.  相似文献   
107.
108.
The central nervous system has limited capacity for regeneration after traumatic injury. Transplantation of neural stem/progenitor cells (NPCs) has been proposed as a potential therapeutic approach while insulin‐like growth factor I (IGF‐I) has neuroprotective properties following various experimental insults to the nervous system. We have previously shown that NPCs transduced with a lentiviral vector for IGF‐I overexpression have an enhanced ability to give rise to neurons in vitro but also in vivo, upon transplantation in a mouse model of temporal lobe epilepsy. Here we studied the regenerative potential of NPCs, IGF‐I‐transduced or not, in a mouse model of hippocampal mechanical injury. NPC transplantation, with or without IGF‐I transduction, rescued the injury‐induced spatial learning deficits as revealed in the Morris Water Maze. Moreover, it had beneficial effects on the host tissue by reducing astroglial activation and microglial/macrophage accumulation while enhancing generation of endogenous oligodendrocyte precursor cells. One or two months after transplantation the grafted NPCs had migrated towards the lesion site and in the neighboring myelin‐rich regions. Transplanted cells differentiated toward the oligodendroglial, but not the neuronal or astrocytic lineages, expressing the early and late oligodendrocyte markers NG2, Olig2, and CNPase. The newly generated oligodendrocytes reached maturity and formed myelin internodes. Our current and previous observations illustrate the high plasticity of transplanted NPCs which can acquire injury‐dependent phenotypes within the host CNS, supporting the fact that reciprocal interactions between transplanted cells and the host tissue are an important factor to be considered when designing prospective cell‐based therapies for CNS degenerative conditions. GLIA 2016;64:763–779  相似文献   
109.
Deficiencies in vitamin D, folate and cobalamin are common in Inflammatory Bowel Disease (IBD). The aim of the present study was to assess serum levels of these vitamins in IBD adults based on the respective serum cut off values for vitamin deficiencies, and to explore possible associations with IBD-related biomarkers and nutritional intake. A cross-sectional study was carried out and patients with Crohn’s disease (CD) or ulcerative colitis (UC) from Attica-Greece were enrolled. Medical and dietary history, clinical examination and blood/stool biomarkers were evaluated. In total, 87 patients participated in the study. Serum levels of 25(OH)D, folate and cobalamin were deficient in 36.8%, 18.4% and 5.7% of patients, respectively. Linear regression analysis in the overall patients showed positive associations between (a) serum 25(OH)D with serum iron (beta = 0.083, p = 0.005) and (b) serum cobalamin with total bilirubin (beta = 0.357, p = 0.020) and direct bilirubin (beta = 0.727, p = 0.033), adjusting for age, sex, body mass index (BMI), disease activity and duration, smoking, nutritional intake and season of recruitment. In CD patients (N = 54), a negative linear association between serum folate and fecal lysozyme was evident (beta = −0.009, p = 0.020). No associations were found for UC patients (N = 33). The serum vitamin profile may be a complementary biomarker for the evaluation of disease activity next to serum and stool inflammatory biomarkers.  相似文献   
110.
Hypotension commonly occurs during hemodialysis (HD). Hypotension can result from an absolute reduction in plasma volume following excessive ultrafiltration or from a reduction in vascular tone. We hypothesized that changes in vascular tone could occur during dialysis. Aortic pulse wave velocity (aPWV) was measured in 197 HD patients, mean age 63.3 ± 16.6 years, 62% male, 49% diabetic, during a single HD session. aPWV did not change (9.6 ± 2.2 vs. 9.6 ± 2.2 m/s) with HD. Systolic blood pressure (SBP) declined from 151 ± 31 to 147 ± 32 after 20 min and to 140 ± 36 mm Hg on completion of HD (P < 0.05), with an ultrafiltration volume of 2.2 ± 0.9 L over a 3.9 ± 0.4 h HD session. Aortic SBP declined from 154 ± 32 to 146 ± 29 after 20 min and 143 ± 35 at the end of HD, P < 0.001. Aortic augmentation index (Aortic Aix) decreased from 65% (52–79%) to 36.7% (23.3–52.9%) by 20 min and to 34.3 (15.1–49.1%) on completion of HD (P < 0.05), and brachial augmentation index (brachial Aix) from 5.7% (?25.2 to 27.5%) to ?1.9% (?2.2 to 30.1%) and ?6.6% (?44 to 22.7%), respectively, P < 0.05. Diastolic reflection area (DRA) increased from 36.7 (27.9–46.3) to 40.4 (32.2–51) after 20 min and 47.1 (34.2–60.5) on completion of HD, P < 0.05. We report changes in arterial tone within 20 min of starting HD, when minimal ultrafiltration has occurred, suggesting that volume changes may not be the only predisposing cause of intradialytic hypotension. The combination of a fall in SBP and a rise in DRA would suggest a reduction in coronary blood flow in keeping with reports of “myocardial stunning” during HD.  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