全文获取类型
收费全文 | 9349篇 |
免费 | 1360篇 |
国内免费 | 242篇 |
专业分类
耳鼻咽喉 | 31篇 |
儿科学 | 83篇 |
妇产科学 | 23篇 |
基础医学 | 1030篇 |
口腔科学 | 167篇 |
临床医学 | 857篇 |
内科学 | 790篇 |
皮肤病学 | 51篇 |
神经病学 | 1449篇 |
特种医学 | 2502篇 |
外国民族医学 | 4篇 |
外科学 | 370篇 |
综合类 | 913篇 |
预防医学 | 386篇 |
眼科学 | 1107篇 |
药学 | 743篇 |
2篇 | |
中国医学 | 146篇 |
肿瘤学 | 297篇 |
出版年
2024年 | 16篇 |
2023年 | 124篇 |
2022年 | 177篇 |
2021年 | 431篇 |
2020年 | 396篇 |
2019年 | 448篇 |
2018年 | 409篇 |
2017年 | 529篇 |
2016年 | 500篇 |
2015年 | 487篇 |
2014年 | 709篇 |
2013年 | 716篇 |
2012年 | 623篇 |
2011年 | 651篇 |
2010年 | 491篇 |
2009年 | 492篇 |
2008年 | 464篇 |
2007年 | 374篇 |
2006年 | 362篇 |
2005年 | 316篇 |
2004年 | 270篇 |
2003年 | 229篇 |
2002年 | 202篇 |
2001年 | 173篇 |
2000年 | 129篇 |
1999年 | 129篇 |
1998年 | 85篇 |
1997年 | 104篇 |
1996年 | 85篇 |
1995年 | 104篇 |
1994年 | 88篇 |
1993年 | 57篇 |
1992年 | 52篇 |
1991年 | 45篇 |
1990年 | 47篇 |
1989年 | 54篇 |
1988年 | 36篇 |
1987年 | 28篇 |
1986年 | 33篇 |
1985年 | 45篇 |
1984年 | 47篇 |
1983年 | 25篇 |
1982年 | 40篇 |
1981年 | 22篇 |
1980年 | 29篇 |
1979年 | 11篇 |
1978年 | 22篇 |
1977年 | 14篇 |
1976年 | 12篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
从主张治未病、重视整体性、注重从脏腑经络辨治、强调辨病与辨证相结合以及灵活运用内治法和外治法五个方面,阐述了《金匮要略》辨证论治的思想对后世耳鼻喉科疾病治疗的影响。认为现代耳鼻喉疾病的发生虽然与古代有所不同,但是《金匮要略》的论治思想和治疗法则仍然对现代耳鼻喉科的临床发挥着重要的指导作用。 相似文献
52.
Yanxin Wang Pik-To Cheung Gary X. Shen Inderjeet Bhatia Ed Xue Wu Deqiang Qiu Pek-Lan Khong 《International journal of developmental neuroscience》2007,25(1):1-5
PURPOSE: In a neonatal rat model of hypoxic-ischemic (HI) brain injury, using T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI), we aim to determine the best MRI method of lesion quantification that reflects infarct size. MATERIALS AND METHODS: Twenty 7-day-old rats underwent MRI 24h after HI brain injury was induced. Lesion size relative to whole brain was measured using T2WI and apparent diffusion coefficient (ADC) maps, applying thresholds of 60%, 70% and 80% contralateral control hemisphere mean ADC, and at day 10 post-HI on pathology with TTC staining. Multiple linear regression analysis was used to study the relationships between lesion size at MRI and pathology. RESULTS: Lesion size measurement using all MRI methods significantly correlated with infarct size at pathology; using T2WI, r=0.808 (p<0.001), using 80% ADC, 70% ADC and 60% ADC thresholds, r=0.888 (p<0.001), 0.761, (p<0.001) and 0.569 (p=0.014), respectively. Eighty percent ADC threshold was found to be the only significant independent predictor of final infarct volume (adjusted R(2)=0.775). CONCLUSION: At 24h post-HI, lesion size on DWI, using 80% ADC threshold is the best predictor of final infarct volume. Although T2WI performed less well, it has the advantage of superior spatial resolution and is technically less demanding. These are important considerations for experiments which utilize MRI as a surrogate method for lesion quantification in the neonatal rat HI model. 相似文献
53.
q-Space diffusion of myelin-deficient spinal cords. 总被引:1,自引:0,他引:1
The apparent water diffusion anisotropy in white matter (WM) of excised spinal cords of myelin-deficient (md) rats and their age-matched controls was studied by high-b-value q-space diffusion MRS and MRI at different diffusion times. Non-monoexponential signal decay was observed at long diffusion times. The mean displacements in the md spinal cords were found to be higher than those of the controls. The apparent anisotropy (AA) of the fast-diffusing component was found to decrease more dramatically with the increase in diffusion time for the md spinal cords as compared with controls, whereas the AA of the slow-diffusing component in the controls was found to increase with the increase in diffusion time while that of the md cords decreased with the increase in diffusion time. When diffusion MRI was performed, similar diffusion anisotropy was extracted for the md and control spinal cords at diffusion times of 22 and 50 ms. Only at a diffusion time of about 200 ms was a significant difference obtained in the AA of the two groups. This originates from the much smaller increase in the mean displacement perpendicular to the fiber direction in the control group vs. the md group when the diffusion time was increased. 相似文献
54.
Background: The slitlamp can be used to estimate the anterior chamber depth (ACD). The length of a slit object is increased until the corneal and iris/lens images appear to just touch. Multiplying the just‐touching‐slit‐length (JTSL) by a conversion factor gives an estimate of the ACD as measured by ultrasonography. The purpose of this study was to determine if central corneal thickness (CCT) affects the accuracy of this technique. Methods: The ACD of 50 subjects was measured by A‐scan ultrasonography and estimated by the slitlamp technique. CCT was measured by ultrasonic pachometry. The refractive error was determined subjectively. Results: The average ultrasonographic ACD for all subjects was 3.32 ± 0.65 mm. The average JTSL was 2.46 ± 0.38 mm. The conversion ratio between the ultrasonographic ACD and the average JTSL was 1.35. The predicted ACD using the regression equation of JTSL on the ultrasound anterior chamber depth (USACD) was 3.32 ± 0.54 mm. The corresponding value using the regression equation of JTSL and CCT on USACD was exactly the same, that is, 3.32 ± 0.54 mm. Conclusion: Incorporation of CCT into a regression equation does not improve the accuracy of the Smith technique. 相似文献
55.
Propriospinal myoclonus: utility of magnetic resonance diffusion tensor imaging and fiber tracking. 总被引:1,自引:0,他引:1
Emmanuel Roze Emmanuelle Apartis Marie Vidailhet Valérie Cochen Yara Beaugendre Jean-Marc Trocello Pierre Lasjaunias Denis Ducreux 《Movement disorders》2007,22(10):1506-1509
Propriospinal myoclonus (PSM) is a rare movement disorder characterized by involuntary spinal-generated muscular jerks that spread rostrally and caudally to other spinally innervated muscles. Most patients have no clear etiology, and conventional MRI of the spinal cord is generally normal. Here we report the use of magnetic resonance diffusion tensor imaging (DTI) and fiber tracking to detect tract-specific abnormalities in a patient with propriospinal myoclonus. As the patient had the fragile-X premutation and antithyroid antibodies, spinal cord DTI abnormalities may be related to these conditions. Tract-specific analysis may provide new insights into the pathophysiology of propriospinal myoclonus. 相似文献
56.
Diffusion-weighted imaging in brain aspergillosis 总被引:1,自引:0,他引:1
M. Charlot J.-B. Pialat N. Obadia A. Boibieux N. Streichenberger D. Meyronnet F. Cotton 《European journal of neurology》2007,14(8):912-916
Brain aspergillosis is a rare pathology, occurring mainly in immunocompromised patients, responsible for multiple cerebral septic infarctions. Some researchers have described magnetic resonance (MR) findings in cerebral invasive aspergillosis, but diffusion-weighted imaging (DWI) has rarely been reported, especially in typical non-enhancing lesions, while it may be helpful for early differential diagnosis and may allow earlier antifungal treatment. We describe three cases of patients presenting brain aspergillosis, with MR imaging including diffusion-weighted sequences and apparent diffusion coefficient (ADC) cartography. The three patients described in this study presented a total of 23 circular lesions, and one patient presented an infarction area in the territory of the right middle cerebral artery. Lesions were ring-enhancing for one patient, and presented no enhancement for the other two. Eleven lesions were very bright on DWI, with reduced ADC values. Twelve lesions, either enhancing or not enhancing, presented a 'target-like' aspect with central and peripheral hypointense areas on DWI, corresponding to higher ADC value areas, and intermediate marked hypersignal on DWI. This typical aspect of aspergillosis lesions on DWI may allow early diagnosis and treatment of cerebral aspergillosis, and is helpful for differentiating aspergillosis lesions from other infectious or malignant lesions affecting immunocompromised patients. 相似文献
57.
French Donna L. Häglund Bert O. Himmelstein Kenneth J. Mauger John W. 《Pharmaceutical research》1995,12(10):1513-1520
Purpose. The objective of this study is to correlate drug release mechanism with measured drug concentration profiles in gel layers of Carbopol® matrices containing mesalamine or benzoic acid.
Methods. Release rate experiments with Carbopol® matrices were performed using a rotating disk apparatus. Matrices were frozen and the gel layer in the matrices was sliced using a microtome in a cryostat. Drug concentration profiles were determined by direct measurement of the concentration of the drug in the gel slices. The pH of the slices was measured using microelectrodes, and water content was measured by Karl Fisher titration.
Results. The concentration gradient in mesalamine matrices decreased over time and correlated with square root of time release rate kinetics. The concentration profiles of benzoic acid were unchanged over time and correlated with zero order release rate kinetics. Carbopol gel layers were highly hydrated (93–95% water). Gel layers in matrices with mesalamine had a more alkaline microenvironmental pH. This higher pH resulted in increased growth of the thickness of the gel layer and a reduction drug diffusivity in comparison to benzoic acid matrices.
Conclusions. The release rate kinetics of mesalamine and benzoic acid correlated to the measured concentration profiles. The shape of the concentration profiles is determined by the rate of growth of the Carbopol® gel layer and drug diffusivity. 相似文献
58.
Anieta M. Sieuwerts Jan G. M. Klijn John A. Foekens 《Clinical & experimental metastasis》1997,15(1):53-62
The Boyden chamber assay is widely used for in vitro measurement of the invasive capacity of cells. However, results can be affected significantly if certain precautions are not taken. Using the Boyden chamber assay we investigated in vitro the invasive potential of a variety of human gynecological tumor cell lines to degrade and migrate through the artificial basement membrane matrix Matrigel. However, in the absence of this Matrigel layer large differences were observed in the ability of cells to adhere to, migrate through and attach to the lower side of the filter membranes. These differences were influenced by cell density, degree of directional locomotion, and the size of the filter pores. To adjust for these influences (which are not directly correlated to the capacity of cells to traverse the Matrigel layer), invasion results were corrected for the ability of cells to migrate through the filter membrane. In addition, the invasion of MDA-MB-231 cells was used as an internal standard to compensate for variations in the Matrigel layer between different experiments. Overall, in our experimental set up, the five human breast cancer cell lines were the most invasive (mean invasion ± SEM relative to MDA-MB-231 invasion: 104.7 ± 6.1%), the five human ovarian cancer cell lines the least invasive (60.2 ± 2.2%) and the six human endometrial cancer cell lines showed an intermediate capacity (79.1 ± 3.5%). In conclusion, the Boyden chamber assay can be used reliably for studying the invasive potential of cells in vitro, if the ability of the cells to migrate through the filter is taken into account, and a reference cell line is included to enable comparison of the data obtained from independently performed experiments on different cell lines. 相似文献
59.
T. Otsuka H. Zaraket T. Takano K. Saito S. Dohmae W. Higuchi T. Yamamoto 《Clinical microbiology and infection》2007,13(3):325-327
In total, 269 methicillin-resistant Staphylococcus aureus (MRSA) and 434 methicillin-susceptible S. aureus (MSSA) isolates were investigated to determine their macrolide-lincosamide-streptogramin B (MLS(B)) resistance phenotypes and genotypes. The constitutive phenotype (61.3% in MRSA, 1.3% in MSSA) and erm(A) gene predominated among the 261 erythromycin-resistant MRSA isolates, while the inducible phenotype (38.7% in MRSA, 94.0% in MSSA) and erm(C) gene were more prevalent among the 150 erythromycin-resistant MSSA isolates. There was a higher incidence of the MLS(B) inducible phenotype compared with other countries, perhaps because MLS(B) antibiotics are not recommended as first-line agents against S. aureus in Japan. 相似文献
60.
A systematic search of studies of intrapartum management of the nuchal umbilical cord at term found no published controlled studies in this area. A postal survey containing both structured and open questions and a request for local protocols and guidelines was sent to all 637 midwives in 7 maternity units in England. There were 401 (63%) responses. There appeared to be no unit guidelines for this area of practice. Midwife approaches to nuchal cord during birth varied, and included clamping and cutting of loose nuchal cords and a hands-off approach to tight nuchal cords. Reasons for specific actions included doing what had been taught during midwifery training and learning from previous personal experiences. Theories of diffusion of innovation and of planned behaviour may provide a conceptual basis for understanding the adoption of specific practices. Future qualitative and controlled studies are needed to explore the nature and consequences of varying approaches to intrapartum nuchal cord management. 相似文献