全文获取类型
收费全文 | 500篇 |
免费 | 36篇 |
国内免费 | 8篇 |
专业分类
儿科学 | 51篇 |
妇产科学 | 3篇 |
基础医学 | 52篇 |
口腔科学 | 11篇 |
临床医学 | 71篇 |
内科学 | 97篇 |
皮肤病学 | 2篇 |
神经病学 | 8篇 |
特种医学 | 136篇 |
外科学 | 21篇 |
综合类 | 8篇 |
预防医学 | 20篇 |
眼科学 | 5篇 |
药学 | 27篇 |
中国医学 | 2篇 |
肿瘤学 | 30篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 10篇 |
2009年 | 14篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 8篇 |
2005年 | 9篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 38篇 |
1997年 | 59篇 |
1996年 | 40篇 |
1995年 | 32篇 |
1994年 | 34篇 |
1993年 | 25篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 3篇 |
1989年 | 17篇 |
1988年 | 19篇 |
1987年 | 16篇 |
1986年 | 19篇 |
1985年 | 19篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1975年 | 5篇 |
排序方式: 共有544条查询结果,搜索用时 296 毫秒
81.
Glomus tympanicum chemodectomas are benign neoplasms that develop from normal glomus bodies located along the Jacobson (tympanic) nerve in the middle ear. The medical charts and radiographic studies of 55 patients with these tumors were reviewed. Women outnumbered men in a ratio of 3.5:1, and the patients' average age when they initially reported symptoms was 52 years. Tinnitus, ear pulsations, and diminished hearing were the most frequent symptoms. No patient had a second chemodectoma, and none of seven patients who were tested had elevated neuroendocrine compounds. Review of the radiographic examinations showed that direct coronal, thin-section computed tomography (CT) was the most sensitive means of demonstrating glomus tympanicum chemodectomas. Magnification angiography was also a sensitive diagnostic study, typically depicting a trapezoidal, hypervascular, middle-ear mass that appeared initially in the middle-to-late arterial phase and quickly disappeared in the venous phase. Differentiation from an aberrant internal carotid artery is critical to prevent arterial biopsy. 相似文献
82.
Pheochromocytoma and the normal adrenal medulla: improved visualization with I-123 MIBG scintigraphy 总被引:1,自引:0,他引:1
Lynn MD; Shapiro B; Sisson JC; Beierwaltes WH; Meyers LJ; Ackerman R; Mangner TJ 《Radiology》1985,155(3):789-792
The radiopharmaceutical iodine 131 metaiodobenzylguanidine (I-131 MIBG) has been shown to locate pheochromocytomas scintigraphically with a false-negative rate of approximately 13%. To improve image quality and reduce the false-negative rate, I-123 was examined as a radioactive label for MIBG, as it has many advantages over I-131, including superior dosimetry and better detection efficiency. Diagnostic doses of 0.5 mCi (18.5 MBq) I-131 MIBG and 10.0 mCi (370.0 MBq) I-123 MIBG with nearly equivalent radiation dosimetries were compared in 18 patients with known or suspected pheochromocytomas. Images of superior quality were obtained with I-123 MIBG in 18 of 18 patients, and in eight cases lesions not visualized on I-131 MIBG scintigraphy were portrayed. A further advantage of I-123 MIBG is that it permits single photon emission computed tomography (SPECT). This was performed in six cases and provided additional information in three cases. The adrenal medullae were definitely visualized using I-123 scintigraphy in eight of 14 patients still possessing adrenal glands, whereas I-131 MIBG images portrayed the adrenal medulla in only one of 14 cases. Five remaining patients had multiple abdominal tumor deposits that were difficult to differentiate from normal adrenal medullae. 相似文献
83.
Matson GB; Twieg DB; Karczmar GS; Lawry TJ; Gober JR; Valenza M; Boska MD; Weiner MW 《Radiology》1988,169(2):541-547
Localized phosphorus-31 magnetic resonance (MR) spectroscopy in humans has previously been accomplished with surface coils by means of depth-resolved surface coil spectroscopy or rotating frame experiments, in which the extent of tissue sampled critically depends on surface coil placement. The authors' goal was to modify the surface coil image-selected in vivo spectroscopy (ISIS) experiment to accomplish three-dimensional volume selection through application of selective pulses in the presence of B0 gradients. Advantages of ISIS include the ability to use proton images to define the volume of interest (VOI) and reduced dependence on exact positioning of the surface coil. However, rapid replication of the surface coil ISIS experiment can cause spectral contamination from signals originating outside the VOI. A modified version of the ISIS experiment was developed to alleviate contamination under conditions of rapid replication. Applications of localized P-31 MR spectroscopy for observation of high-energy phosphorus metabolites are presented in human liver, heart, and transplanted and normal kidney. 相似文献
84.
Endoscopic retrograde biliary drainage 总被引:1,自引:0,他引:1
85.
Rosen BR; Fleming DM; Kushner DC; Zaner KS; Buxton RB; Bennet WP; Wismer GL; Brady TJ 《Radiology》1988,169(3):799
86.
Greif WL; Buxton RB; Lauffer RB; Saini S; Stark DD; Wedeen VJ; Rosen BR; Brady TJ 《Radiology》1985,157(2):461-466
Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by altering tissue relaxation times. The effect of these changes on MR image intensity depends in part on the choice of operator-controlled pulse sequence parameters. With the newly described paramagnetic hepatobiliary contrast agent, iron(III) ethylenebis-(2-hydroxyphenylglycine), Fe(EHPG)-, an in vivo experimental analysis of pulse sequence optimization was performed on the rat. We compared the enhancement of the liver divided by background noise, EL/N, of standard inversion-recovery (IR) and spin-echo (SE) T1-weighted pulse sequences and several pulse sequences theoretically predicted to have improved EL/N. Optimization of the echo time (TE = TEmin) gave a substantial (greater than 60%) increase in EL/N over the standard IR and SE pulse sequences. Images obtained with optimized repetition rate and inversion time gave only a slight additional improvement. Within the uncertainties of our relaxation measurements, the measured changes in EL/N with pulse sequence optimization corresponded well with theoretical predictions. With the experimental and theoretical data, the importance of using a short echo time to obtain maximal T1 contrast in contrast-enhanced MR imaging and the relative merits of optimized SE versus IR pulse sequences for contrast-enhanced MR imaging are discussed. 相似文献
87.
INTRODUCTION
The management of Hirschsprung’s disease continues to evolve. This questionnaire survey aimed to determine current surgical management strategies for Hirschsprung’s disease in Britain.SUBJECTS AND METHODS
The survey was sent electronically to all British paediatric surgeons. Initial questions explored individual experience and regional service provision. Additional questions, reserved for surgeons who perform definitive Hirschsprung’s disease surgery, addressed specific clinical scenarios.RESULTS
Surveys were sent to 142 surgeons yielding 85 responses. After exclusions, 64 surveys from 21 centres were analysed. Forty-seven respondents worked in centres with designated ‘Hirschsprung’s disease surgeons’. Forty respondents perform definitive Hirschsprung’s disease surgery. In a well neonate with left-sided Hirschsprung’s disease, 34 of 40 surgeons favour primary pull-through following bowel decompression with rectal washouts; 35 of 40 surgeons aim to perform definitive surgery at less than 3 months of age, with 17 favouring laparoscopic-assisted Soave–Boley and 15 favouring an open Duhamel pull-through. Of the 40 surgeons, 36 use a staged approach to right-sided/total colonic Hirschsprung’s disease with 23 favouring a Duhamel or Long Duhamel pull-through.CONCLUSIONS
The primary pull-through, using an open Duhamel or laparoscopic-assisted Soave–Boley technique, during the first 3 months of life, has become the operative strategy of choice in rectosigmoid Hirschsprung’s disease in Britain. Marked variation in practice remains for right-sided Hirschsprung’s disease. 相似文献88.
Pathophysiological mechanisms of dominant and recessive KVLQT1 K+ channel mutations found in inherited cardiac arrhythmias 总被引:9,自引:0,他引:9
Wollnik B; Schroeder BC; Kubisch C; Esperer HD; Wieacker P; Jentsch TJ 《Human molecular genetics》1997,6(11):1943-1949
The inherited long QT syndrome (LQTS), characterized by a prolonged QT
interval in the electrocardiogram and cardiac arrhythmia, is caused by
mutations in at least four different genes, three of which have been
identified and encode cardiac ion channels. The most common form of LQTS is
due to mutations in the potassium channel gene KVLQT1, but their effects on
associated currents are still unknown. Different mutations in KVLQT1 cause
the dominant Romano-Ward (RW) syndrome and the recessive Jervell and
Lange-Nielsen (JLN) syndrome, which, in addition to cardiac abnormalities,
includes congenital deafness. Co- expression of KvLQT1 with the IsK protein
elicits slowly activating potassium currents resembling the cardiac Iks
current. We now show that IsK not only changes the kinetics of KvLQT1
currents, but also its ion selectivity. Several mutations found in RW,
including a novel mutation (D222N) in the putative channel pore, abolish
channel activity and reduce the activity of wild-type KvLQT1 by a
dominant-negative mechanism. By contrast, a JLN mutation truncating the
carboxyterminus of the KvLQT1 channel protein abolishes channel function
without having a dominant-negative effect. This fully explains the
different patterns of inheritance. Further, we identified a novel splice
variant of the KVLQT1 gene, but could not achieve functional expression of
this nor of a previously described heart-specific isoform.
相似文献
89.
90.
低聚果糖口服补液盐的试制 总被引:8,自引:0,他引:8
目的:改良口服补液盐(ORS),使其具有微生态调节作用、并与肠道内渗透压相似。方法:将氯化钠2.6g、氯化钾1.5g、枸橼酸钠2.9g、低聚果糖(FOS)20g和葡萄糖10g等混合后低聚果糖口服液盐(FOS-ORS)。密封包装,使用时加开水1000ml冲服。可采用高效液相色谱法测定FOS的含量。结果:FOS-ORS为白色散剂,加水后为无色透明液体,味甜中微咸,其浓度(mmol/L)为钠75、钾20 相似文献