全文获取类型
收费全文 | 21577篇 |
免费 | 1938篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 238篇 |
儿科学 | 665篇 |
妇产科学 | 404篇 |
基础医学 | 3022篇 |
口腔科学 | 327篇 |
临床医学 | 2331篇 |
内科学 | 4251篇 |
皮肤病学 | 309篇 |
神经病学 | 2003篇 |
特种医学 | 669篇 |
外国民族医学 | 3篇 |
外科学 | 2792篇 |
综合类 | 498篇 |
一般理论 | 14篇 |
预防医学 | 2241篇 |
眼科学 | 725篇 |
药学 | 1602篇 |
中国医学 | 23篇 |
肿瘤学 | 1438篇 |
出版年
2022年 | 151篇 |
2021年 | 325篇 |
2020年 | 248篇 |
2019年 | 365篇 |
2018年 | 376篇 |
2017年 | 293篇 |
2016年 | 341篇 |
2015年 | 399篇 |
2014年 | 562篇 |
2013年 | 828篇 |
2012年 | 1227篇 |
2011年 | 1313篇 |
2010年 | 634篇 |
2009年 | 665篇 |
2008年 | 1101篇 |
2007年 | 1249篇 |
2006年 | 1190篇 |
2005年 | 1208篇 |
2004年 | 1177篇 |
2003年 | 1011篇 |
2002年 | 1002篇 |
2001年 | 464篇 |
2000年 | 488篇 |
1999年 | 499篇 |
1998年 | 305篇 |
1997年 | 227篇 |
1996年 | 231篇 |
1995年 | 208篇 |
1994年 | 173篇 |
1993年 | 158篇 |
1992年 | 322篇 |
1991年 | 329篇 |
1990年 | 309篇 |
1989年 | 312篇 |
1988年 | 286篇 |
1987年 | 269篇 |
1986年 | 297篇 |
1985年 | 260篇 |
1984年 | 221篇 |
1983年 | 175篇 |
1982年 | 165篇 |
1981年 | 131篇 |
1980年 | 127篇 |
1979年 | 216篇 |
1978年 | 150篇 |
1977年 | 116篇 |
1976年 | 106篇 |
1975年 | 106篇 |
1974年 | 116篇 |
1973年 | 137篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
A comparison of the effects of oral nadolol and topical timolol on intraocular pressure, blood pressure, and heart rate. 总被引:1,自引:1,他引:0 下载免费PDF全文
We compared the effects of oral nadolol 20 mg once daily and topical timolol 0.25% twice daily on the intraocular pressures of 22 glaucoma suspects, in a 12 week double-masked crossover study. Both nadolol and timolol reduced intraocular pressure (p less than 0.001). The reductions in intraocular pressure did not differ significantly after two weeks and four weeks of treatment. Nine of these subjects underwent treadmill exercise tests in order to compare the effects of nadolol and timolol on the cardiovascular system. The effects of the two treatments on blood pressure were comparable, but nadolol caused a significantly greater reduction in heart rate than timolol at rest (p less than 0.05). Nadolol reduces intraocular pressure effectively and may prove a useful alternative treatment for chronic simple glaucoma. 相似文献
62.
Richard C. Semelka Suvipapun Worawattanakul Nikolaos L. Kelekis Gesine John John T. Woosley Mark Graham William G. Cance 《Journal of magnetic resonance imaging : JMRI》1997,7(6):1040-1047
This study compares liver lesion detection, characterization, and effect on patient management between single-phase spiral CT and MRI using spoiled gradient echo (SGE), T2-weighted fat-suppressed spin echo, and serial post gadolinium SGE. All patients with suspected liver lesions who underwent spiral CT and MRI within a 1-month period between January 1993 and September 1996 were included in the study. Spiral CT and MRI were interpreted prospectively in a blinded fashion by separate individual experienced investigators, and lesion detection and characterization were determined. Confirmation was obtained by surgery (6 patients), biopsy (18 patients), imaging follow-up (36 patients), or combined reading of all imaging studies and clinical follow-up (29 patients). Effect on patient management was determined by combined chart review and interview of the patients' physicians and by retrospective clinical assessment performed by a surgical oncologist and medical oncologist separately. Eighty-nine patients were included in the study. Regarding true positive lesion detection, 295 and 519 lesions were detected on spiral CT and MR images, respectively, which was significantly different on a patient-by-patient basis (P < .001). More lesions were detected on MR than on spiral CT in 44 of 89 patients (49.4%), and 11 of these 44 patients had lesions shown on MRI in whom no lesions were apparent on CT images. No patients had true positive lesions shown on spiral CT that were not shown on MRI. Regarding lesion characterization, 129 and 466 lesions were characterized on spiral CT and MRI images, respectively, which was significantly different on a patient-by-patient basis (P < .001). More lesions were characterized on MR than CT images in 67 patients (75.3%). Regarding effect on patient management, chart review with physician interview demonstrated that findings on MRI provided information that altered patient management as compared with findings on spiral CT in 57 patients. Retrospective clinical evaluation by the surgical and medical oncologist showed that MRI was considered to have a greater effect on patient management than spiral CT in 58 and 55 patients, respectively. Comparing current MRI technique to single-phase spiral CT, MRI detected more lesions in 49.4% and characterized more lesions in 75.3% of patients investigated for focal liver disease. MRI had a greater effect on patient management in each of the three methods than singlephase spiral CT in more than 61% of patients. 相似文献
63.
S D Graham 《The Urologic clinics of North America》1992,19(3):541-548
Immunobiology techniques that once were the domain of research are increasingly being applied in the clinic. Transitional epithelium of the bladder undergoes some recognized immunologic changes as it becomes malignant, and their detection may have prognostic value. Examples of such changes are deletion of the ABO(H) blood group antigens, inappropriate expression of Lewis antigens, loss of beta-2 microglobulin and the MHC class 1 heavy chain, and alterations in the production of cellular adhesion molecules and integrins. Other possibly useful markers are ras oncogene products, Thomsen-Friedenreich antigen, epidermal growth factor receptor, and perhaps antigens unique to transitional-cell carcinoma. 相似文献
64.
Graham C Scanlon Mark S Wallace J Sorin Ispirescu Gery Schulteis 《Journal of investigative medicine》2006,54(5):238-244
BACKGROUND: Intradermal capsaicin is a human pain model that produces reliable pain and sensitization. This model facilitates controlled testing of analgesic efficacy via a crossover design while minimizing confounding variables in clinical pain states and retaining sufficient power with small samples. METHODS: To determine the lowest dose of capsaicin that produces consistent neurosensory measures, we administered 0.1, 1, 10, or 100 microg to healthy volunteers in a blinded manner (N = 19). Pain scores were recorded at 0, 5, 10, 15, and 60 minutes on a visual analog scale from 0 to 100. Areas and intensities of mechanical allodynia (foam brush stimulus) and pinprick hyperalgesia (von Frey test) were quantified at 15 and 60 minutes, as were flare areas. RESULTS: Capsaicin produced dose-dependent increases in spontaneous pain (p = .013), the area and intensity of mechanical allodynia (p = .006 and p < .001, respectively), the area and intensity of pinprick hyperalgesia (p = .010 and p = .014, respectively), and the flare area (p = .010). The 10 microg dose produced greater spontaneous pain than the 1 microg dose (p = .017). The 100 microg dose produced greater spontaneous pain than the 10 microg, but the difference was not statistically significant. CONCLUSION: The 10 and 100 microg capsaicin doses produced robust pain measures across a range of modalities, and lower doses produced minimal effects. Whereas most studies use 100 microg, using a lower dose is reasonable and may facilitate detection of subtle analgesic effects--particularly with nonopioid analgesics--and drugs can be tested in lower doses, minimizing adverse side effects. 相似文献
65.
66.
67.
O W Woltersdorf H Schwam J B Bicking S L Brown S J deSolms D R Fishman S L Graham P D Gautheron J M Hoffman R D Larson 《Journal of medicinal chemistry》1989,32(11):2486-2492
A series of O-acyl derivatives of 6-hydroxybenzothiazole-2-sulfonamide (4, L-643,799) was prepared and the potential utility of each series member as a topically active inhibitor of ocular carbonic anhydrase was determined. In vitro studies showed these esters to be substrates for ocular esterases which liberate 4 during corneal translocation. The most interesting series member, 2-sulfamoyl-6-benzothiazolyl 2,2-dimethylpropionate (22, L-645,151), acting as a prodrug form of 4, was found to enhance delivery through the isolated albino rabbit cornea by 40-fold when compared to the parent phenol 4. Studies in rabbits revealed that 22 is a potent topically active ocular hypotensive carbonic anhydrase inhibitor. 相似文献
68.
Pippa Storey Fred J Frigo R Scott Hinks Bryan J Mock Bruce D Collick Nicole Baker Jonathan Marmurek Simon J Graham 《Magnetic resonance in medicine》2007,57(3):614-619
Partial k-space sampling is frequently used in single-shot diffusion-weighted echo-planar imaging (DW-EPI) to reduce the TE and thereby improve the SNR. However, it increases the sensitivity of the technique to bulk rotational motion, which introduces a phase gradient across the tissue that shifts the echo in k-space. If the echo is displaced into the high spatial frequencies, conventional homodyne reconstruction fails, causing intensity oscillations across the image. Zero-padding, on the other hand, compromises the image resolution and may cause truncation artifacts. We present an adaptive version of the homodyne algorithm that detects the location of the echo in k-space and adjusts the center and width of the homodyne filters accordingly. The adaptive algorithm produces artifact-free images when the echo is shifted into the high positive k-space range, and reduces to the standard homodyne algorithm in the absence of bulk motion. 相似文献
69.
Scott M. Graham M.D. Garth H. Ballantyne M.D. Irvin M. Modlin M.D. 《The American journal of gastroenterology》1987,82(1):82-85
This is the first case report of the preoperative diagnosis of a gastric epithelioid leiomyosarcoma by percutaneous needle biopsy. Preoperative diagnosis facilitated curative surgical resection. Patients may present without symptoms or may report symptoms of peptic ulcer disease or gastrointestinal bleeding. Upper gastrointestinal series is the most useful radiological tool for detecting these lesions. Ultrasound and CT play a useful role in documenting the origin of these large masses, as well as their spread. Endoscopy is being used with increasing frequency, but because these are submucosal lesions diagnosis cannot easily be made through the endoscope. Pathologically, these tumors can be subdivided histologically into a benign epithelioid leiomyoma and two varieties of malignant epithelioid leiomyosarcoma. Prognosis correlates with histological features. Complete surgical resection is the treatment of choice. Chemotherapy or radiotherapy have no proven efficacy in treating epithelioid leiomyosarcoma. Unlike most other gastric malignancies, a favorable prognosis follows successful resection. 相似文献
70.