全文获取类型
收费全文 | 4223篇 |
免费 | 317篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 45篇 |
儿科学 | 159篇 |
妇产科学 | 111篇 |
基础医学 | 657篇 |
口腔科学 | 77篇 |
临床医学 | 415篇 |
内科学 | 1160篇 |
皮肤病学 | 50篇 |
神经病学 | 341篇 |
特种医学 | 136篇 |
外科学 | 459篇 |
综合类 | 39篇 |
一般理论 | 2篇 |
预防医学 | 306篇 |
眼科学 | 93篇 |
药学 | 204篇 |
中国医学 | 12篇 |
肿瘤学 | 294篇 |
出版年
2023年 | 30篇 |
2022年 | 59篇 |
2021年 | 126篇 |
2020年 | 75篇 |
2019年 | 105篇 |
2018年 | 119篇 |
2017年 | 78篇 |
2016年 | 110篇 |
2015年 | 132篇 |
2014年 | 181篇 |
2013年 | 192篇 |
2012年 | 296篇 |
2011年 | 325篇 |
2010年 | 184篇 |
2009年 | 162篇 |
2008年 | 248篇 |
2007年 | 286篇 |
2006年 | 262篇 |
2005年 | 269篇 |
2004年 | 249篇 |
2003年 | 220篇 |
2002年 | 187篇 |
2001年 | 65篇 |
2000年 | 42篇 |
1999年 | 65篇 |
1998年 | 44篇 |
1997年 | 40篇 |
1996年 | 27篇 |
1995年 | 22篇 |
1994年 | 23篇 |
1993年 | 16篇 |
1992年 | 28篇 |
1991年 | 17篇 |
1990年 | 20篇 |
1989年 | 13篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 18篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1981年 | 11篇 |
1979年 | 14篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 23篇 |
1975年 | 12篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1971年 | 9篇 |
排序方式: 共有4560条查询结果,搜索用时 234 毫秒
11.
The authors report the case of a patient with a Hickman catheter that migrated into the lung parenchyma. The resultant inadvertent infusion of 5-fluorouracil caused necrotizing chemical pneumonitis. Possible mechanisms of catheter migration include the lateral orientation of the catheter tip and the partial thrombosis of the innominate vein and superior vena cava. The patient recovered but had residual contraction fibrosis of the right upper lobe of the lung. 相似文献
12.
Ren Drucker-Colín Leticia Verdugo-Díaz Milagros Mndez Jos Carrillo-Ruiz Consuelo Morgado-Valle Arturo Hernndez-Cruz Gabriel Corkidi 《Molecular and cellular neurosciences》1994,5(6)
Adrenal chromaffin cells in vitro respond to nerve growth factor (NGF) by expressing neuronal traits. Low frequency magnetic (LFM) field stimulation, while inducing a variety of effects on several cell types, has never been studied as to its effects on chromaffin cell cultures. The purpose of this study was to compare the effects of LFM field stimulation with that of NGF on the morphological phenotype, on noradrenaline (NA) release, and on membrane excitability of cultured chromaffin cells. We also tested the effects of grafting LFM and NGF-treated chromaffin cells into the caudate nucleus of rats with 6-hydroxydopamine lesions of the nigrostriatal pathway. The results of this study showed that LFM field stimulation produced neurite growth of cultured chromaffin cells in a manner similar to that of NGF exposure. The combination of the two procedures did not induce changes above those observed by NGF alone. Both NGF- and LFM-treated chromaffin cells released [3H]NA equally in response to a depolarizing concentration of KCl. On the other, Na+ current density of LFM field stimulation increased, but to a lesser extent than that seen in NGF-treated cells. In addition both types of cells when transplanted into nigrostriatal-lesioned animals induced a similar decrease in the motor asymmetries produced by the lesion. When NGF- or LFM-treated chromaffin cells where compared to untreated control cells, no significant differences were observed in [3H]NA release, on Na+ current densities, or on postgraft motor asymmetries. The results are discussed in terms of the fact that LFM-stimulated cells can be differentiated in a manner similar to NGF-treated cells, by acquiring sympathetic like traits which in turn can diminish motor asymmetries when grafted into nigrostriatal-lesioned rats. 相似文献
13.
14.
Ofelia Dolores Hernández Ángel José Gutiérrez Dailos González‐Weller Gonzalo Lozano Enrique García Melón Carmen Rubio Arturo Hardisson 《Environmental toxicology》2010,25(3):227-233
This document shows the results obtained from a study on the concentration of toxic heavy metals in the internal tissue and exoskeleton of sea urchins, collected from their natural habitat. The levels of lead and cadmium were measured by Graphite Furnace Atomic Absorption Spectrometry. The mean concentrations of lead and cadmium in the internal tissue were 304.04 and 260.54 μg/kg respectively, whereas in the shell they were 185.02 and 142.48 μg/kg. We also performed a statistical analysis of the differences in the distribution of metals between their exoskeleton and their internal content, a correlation study of the metal content in internal tissue and shell and sampling areas, and a correlation study between the metal content and sample size. Since the sea urchin Diadema antillarum presents a wide range of variation in metal content, this study suggests that this species is an excellent bioindicator of heavy metal contamination. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010. 相似文献
15.
E Díaz-Rubio J Jimeno A Antón E Aranda J Sánchez B Massuti J Cruz-Hernández A Carrato M Martin J Belón 《American journal of clinical oncology》1992,15(1):56-60
One hundred sixty consecutive patients with histologically confirmed colorectal cancer (advanced disease) without prior chemotherapy were entered in a randomized trial comparing 5-fluorouracil (5-FU) 1,000 mg/m2 intravenously per day for 5 consecutive days in continuous infusion versus cisplatin (CP) 100 mg/m2 on day 1 plus 5-FU as described on days 2 to 6. In both arms, treatment was recycled every 4 weeks. Both groups were well balanced for age, sex, colon or rectal origin, median time between diagnosis to advanced disease, performance status at entry, and visceral involvement. The overall response rate in the combination and in the single arm were 18 and 23%, respectively. There were no differences in time to progression (a median of 17.8 and 14.9 weeks for CP-5-FU and 5-FU, respectively) and in overall survival (a median of 71.2 and 59.6 weeks, respectively). The incidence of grade 3-4 emesis was significantly higher in the CP-containing chemotherapy (p = .00001). Our study has failed to demonstrate any clinical benefit from adding cisplatin to 5-FU in patients with cancer of the colon and rectum. 相似文献
16.
Resistance exercise training and alendronate reverse glucocorticoid-induced osteoporosis in heart transplant recipients. 总被引:1,自引:0,他引:1
Randy W Braith Peter M Magyari Michael N Fulton Juan Aranda Tracy Walker James A Hill 《The Journal of heart and lung transplantation》2003,22(10):1082-1090
BACKGROUND: Immunosuppression therapy with bolus glucocorticoids causes regional osteoporosis in the axial skeleton of heart transplant recipients (HTR). No preventive strategy is generally accepted for steroid-induced bone loss. METHODS: To determine the efficacy of an anti-osteoporosis regimen that combined a bisphosphonate agent (alendronate sodium) with the osteogenic stimulus of mechanical loading, 25 HTRs were randomly assigned either to a group that received alendronate (10 mg/day) for 6 months (ALEN; n = 8), a group that received alendronate (10 mg/day) and performed specific resistance exercises for 6 months (ALEN + TRN; n = 8) or to a non-intervention control group (CONTR; n = 9). Alendronate was initiated at 2 months after transplantation. Bone mineral density (BMD) of the total body, femur neck and lumbar spine (L-2 and L-3) was measured by dual-energy X-ray absorptiometry before and 2, 5 and 8 months after transplantation. Resistance training consisted of lumbar extension exercise (MedX) performed 1 day/week and 8 variable resistance exercises (MedX) performed 2 days/week. RESULTS: Pre-transplantation BMD values did not differ among the 3 groups. BMD of the total body, femur neck and lumbar vertebra were significantly decreased below baseline at 2 months after transplantation in CONTR (-2.6 +/- 0.9%, -5.1 +/- 1.8%, -12.5 +/- 4.2%, respectively), ALEN (-2.8 +/- 0.8%, -5.3 +/- 1.6%, -12.0 +/- 3.9%) and ALEN + TRN groups (-2.7 +/- 1.0%, -5.6 +/- 2.1%, -11.2 +/- 3.7%). CONTR had further significant losses of BMD after 3 and 6 months. ALEN had no further regional BMD losses after initiation of alendronate therapy. ALEN + TRN restored BMD of the whole body, femur neck and lumbar vertebra to within 0.9%, 2.1%, and 3.4% of pre-transplantation levels, respectively. CONCLUSIONS: Resistance exercise plus alendronate was more efficacious than alendronate alone in restoring BMD in HTRs. Our results indicate that anti-osteoporosis therapy in this population should include both an anti-resorptive agent as well as an osteogenic stimulus, such as mechanical loading. 相似文献
17.
Diagnosis of pulmonary Kaposi's sarcoma with fiberoptic bronchoscopy and endobronchial biopsy. A report of five cases 总被引:1,自引:0,他引:1
Fiberoptic bronchoscopy is a major tool in the diagnostic evaluation of pulmonary disease in patients with the Acquired Immune Deficiency Syndrome. Multiple opportunistic infections and Kaposi's sarcoma affect the lung in this disorder. In contrast to opportunistic infections, Kaposi's sarcoma is rarely reported to be diagnosed by means of bronchoscopy. This report describes five of seven patients in whom endobronchial lesions consistent with submucosal involvement by the tumor were seen, and Kaposi's sarcoma was diagnosed without complication. Kaposi's sarcoma must be considered in the differential diagnosis of pulmonary disease in patients with a proven extrapulmonary tumor focus, and fiberoptic bronchoscopy is the initial diagnostic procedure of choice. Endobronchial Kaposi's sarcoma may be a marker for parenchymal involvement by the tumor. Diagnosis of endobronchial Kaposi's sarcoma can be an important factor in decisions regarding therapy. 相似文献
18.
19.
Banaclocha MA 《Medical hypotheses》2004,63(3):481-484
Despite intensive investigation into the mechanisms underlying the memory process, the physical bases for this superior cognitive function remain elusive. Neuronal activity-associated magnetic fields (NAAMFs) hypothesis of memory suggests that items of information are stored as three-dimensional bundles of magnetic fields associated to the complex but extremely organised cerebral cortex. The present paper proposes a plausible architectural organisation of neuronal activity-associated magnetic fields that may explain how information could be stored in the human cerebral cortex. Magnetic fields generated as consequence of neuronal minicolumns activation could modify the basal "electromagnetic status" of the closest astrocytes allowing codification and storage of information. 相似文献
20.
Fallgatter AJ Esienack SS Neuhauser B Aranda D Scheuerpflug P Herrmann MJ 《Brain topography》2000,12(4):255-261
The P300-amplitude evoked with an acoustic oddball-paradigm is considered the most stable late event-related potential (ERP). This amplitude-index has become a standard parameter in electrophysiology. Recently, a robust ERP-parameter (NoGo-anteriorization, NGA) has been introduced, which reflects spatial brain electrical changes in relation to execution and inhibition of a motor response elicited with a Continuous Performance Test (CPT). The current study refers to the stability of this new topographical ERP-parameter compared to the stability of the classical P300-amplitude. For that purpose, 12 healthy subjects were investigated with both paradigms during recording of a 21-channel EEG. Analysis of the resulting ERPs revealed a very high stability for both, topographical and amplitude index: In every single subject, the brain electrical fields were characterized by a more anterior location in the NoGo- compared to the Go-condition (=NGA) and by higher amplitudes after target compared to distractor condition. T-tests, analyses of the effect size and of the power revealed equivalent differences between the two contrasting conditions for the topographical compared to the amplitude index. These results indicate that the stability of the topographical ERP-parameters elicited with the CPT is sufficient for an electrophysiological standard-index. The possibility to elicit a robust and specific spatial brain activation with the CPT is an ideal completion to the classical P300 amplitude effect and, therefore, hopefully will be a useful expansion of the standard paradigms in electrophysiological laboratories. 相似文献