全文获取类型
收费全文 | 12758篇 |
免费 | 913篇 |
国内免费 | 331篇 |
专业分类
耳鼻咽喉 | 104篇 |
儿科学 | 328篇 |
妇产科学 | 206篇 |
基础医学 | 1835篇 |
口腔科学 | 175篇 |
临床医学 | 1080篇 |
内科学 | 1618篇 |
皮肤病学 | 199篇 |
神经病学 | 735篇 |
特种医学 | 1097篇 |
外国民族医学 | 6篇 |
外科学 | 1933篇 |
综合类 | 1526篇 |
现状与发展 | 1篇 |
预防医学 | 591篇 |
眼科学 | 84篇 |
药学 | 1149篇 |
中国医学 | 255篇 |
肿瘤学 | 1080篇 |
出版年
2023年 | 117篇 |
2022年 | 230篇 |
2021年 | 344篇 |
2020年 | 321篇 |
2019年 | 376篇 |
2018年 | 319篇 |
2017年 | 315篇 |
2016年 | 369篇 |
2015年 | 439篇 |
2014年 | 809篇 |
2013年 | 801篇 |
2012年 | 716篇 |
2011年 | 902篇 |
2010年 | 764篇 |
2009年 | 812篇 |
2008年 | 754篇 |
2007年 | 781篇 |
2006年 | 717篇 |
2005年 | 540篇 |
2004年 | 569篇 |
2003年 | 483篇 |
2002年 | 385篇 |
2001年 | 354篇 |
2000年 | 274篇 |
1999年 | 221篇 |
1998年 | 159篇 |
1997年 | 199篇 |
1996年 | 117篇 |
1995年 | 97篇 |
1994年 | 80篇 |
1993年 | 66篇 |
1992年 | 71篇 |
1991年 | 46篇 |
1990年 | 50篇 |
1989年 | 38篇 |
1988年 | 34篇 |
1987年 | 27篇 |
1986年 | 27篇 |
1985年 | 39篇 |
1984年 | 44篇 |
1983年 | 45篇 |
1982年 | 36篇 |
1981年 | 25篇 |
1980年 | 18篇 |
1979年 | 23篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Roelf Valkema MD Berthe L. F. van Eck-Smit MD Ernst E. van der Wall MD 《Journal of nuclear cardiology》1994,1(6):546-560
Noninvasive techniques for the assessment of cardiac metabolism are important for the detection of potentially salvageable
tissue in jeopardized areas of the myocardium. The correct identification of hibernating and stunned myocardium in patients
with severely depressed cardiac function can have vital therapeutic consequences for the patient. Changes in myocardial fatty
acid and glucose metabolism during acute and prolonged ischemia can be traced by positron-emitting or gamma-emitting radiopharmaceuticals.
Alternatively,31P-labeled magnetic resonance spectroscopy can be used for the assessment of high-energy phosphate metabolism. It is not yet
clear which modality will emerge as the most useful in the clinical setting. Positron emission tomography (PET) that uses
combinations of flow tracers and metabolic tracers offers unique opportunities for quantification and high-resolution static
and rapid dynamic studies. Currently, assessment of glucose metabolism with18F-fluorodeoxyglucose is regarded as the gold standard for myocardial viability and prediction of improvement of impaired contractile
function after revascularization. However, preserved oxidative metabolism may be required for potential functional improvement,
and therefore assessment of residual oxidative metabolism by11C-labeled acetate PET may prove to be more accurate than18F-fluorodeoxyglucose PET, which reflects both anaerobic and oxidative metabolism. Moreover, because fatty acids are metabolized
only aerobically, they are excellent candidates for the clinical assessment of myocardial viability and prediction of functional
improvement after revascularization. Especially derivatives of fatty acids that are not metabolized but accumulate in the
myocyte are attractive for myocardial imaging. Examples are123I-beta-methyl-p-iodophenyl pentadecanoic acid and 15-(o-123I-phenyl)-pentadecanoic acid. These tracers can be detected by planar scintigraphy and single-photon emission computed tomography,
which are more economical and widely available than PET. In addition, 511 keV collimators have been developed recently, making
the detection of positron emitters by planar scintigraphy and single-photon emission computed tomography feasible. The experience
with31P-labeled magnetic resonance spectroscopy in humans is still limited. With current magnetic resonance spectroscopic techniques,
insufficient spatial resolution is achieved for clinical purposes, but the possibility of serial measurements to monitor rapid
changes of phosphate-containing molecules in time makes magnetic resonance spectroscopy very valuable for the research of
myocardial metabolism. 相似文献
72.
Preliminary assessment of fluorine-18 fluorodeoxyglucose positron mission tomography in patients with bladder cancer 总被引:5,自引:1,他引:4
Shigeru Kosuda Paul V. Kison Robert Greenough H. Barton Grossman Richard L. Wahl 《European journal of nuclear medicine and molecular imaging》1997,24(6):615-620
The purpose of this study was to assess the feasibility of imaging of bladder cancer with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) scanning. We studied 12 patients with histologically proven bladder cancer who had undergone surgical procedures and/or radiotherapy. Retrograde irrigation of the urinary bladder with 1000–3710 ml saline was performed during nine of the studies. Dynamic and static PET images were obtained, and standardized uptake value images were reconstructed. FDG-PET scanning was true-positive in eight patients (66.7%), but false-negative in four (33.3%). Of 20 organs with tumor mass lesions confirmed pathologically or clinically, 16 (80%) were detected by FDG-PET scanning. FDG-PET scanning detected all of 17 distant metastatic lesions and two of three proven regional lymph node metastases. FDG-PET was also capable of differentiating viable recurrent bladder cancer from radiation-induced alterations in two patients. In conclusion, these preliminary data indicate the feasibility of FDG-PET imaging in patients with bladder cancer, although a major remaining pitfall is intense FDG accumulation in the urine.
Present address: Department of Radiology, National Defense Medical College, 3-2 Namiki, Tokorozawa 359, Japan 相似文献
73.
B. Pfausler G. Grubwieser S. Bsch H. Vollert M. Herald E. Schmutzhard 《European journal of neurology》1995,2(6):570-572
A 37 year old male was admitted with the diagnosis of bacterial meningitis. Pneumococci were seen in the Gram stain of the cerebrospinal fluid. The clinical condition did not suggest severely raised intracranial pressure, there were no localizing signs and symptoms. CSF was turpid, with 20.100/3/mm3, mainly polymorphonuclear cells. Tumor necrosis factor alpha in CSp was greatly increased with 813 pg/ml. Parallel to the application of intravenous Penicillin G a CSF filtration was carried out. Within 214 h 225 ml CSF were filtrated through a Pall-filter, using a bidirectional pump. Cell count dropped to 720/3 cells/mm3, TNF-alpha to 39 pg/ml. The clinical course was uneventful, on day 12 the patient could be discharged without sequelae. CSF filtration may be a highly effective method to reduce from the CSF pathogenetically important cytokines, such as TNF-alpha, being responsible for intrathecal/meningeal inflammatory processes and triggered by cell-wall components of bacteria, e.g. pneumococci. 相似文献
74.
Fluorine-18-fluorodeoxyglucose positron emission tomography for preoperative parathyroid imaging in primary hyperparathyroidism 总被引:5,自引:3,他引:2
Pierre Melon Andre Luxen Etienne Hamoir Michel Meurisse 《European journal of nuclear medicine and molecular imaging》1995,22(6):556-558
Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging was performed in seven consecutive patients with primary hyperparathyroidism to preoperatively locate parathyroid adenomas. Foci of FDG accumulation corresponding to abnormal parathyroid tissue were observed in two out of nine surgically excised parathyroid adenomas. It was concluded that FDG PET imaging demonstrated a too low sensitivity for systematic preoperative detection and localization of parathyroid glands causing primary hyperparathyroidism. 相似文献
75.
目的探讨PET-CT一体机在恶性肿瘤中的应用价值.方法收集已经明确诊断的全身不同部位的恶性肿瘤病例62例,经PET-CT检查后进行回顾性分析,采用目测和半定量分析方法.结果62例肿瘤病人共检出142个病灶,PET图像阳性率93.55%(58/62);PET图像阴性率6.45%(4/62);PET发现病灶而CT未完全发现病灶率19.4%(12/62);CT发现而PET未见浓聚率6.45%(4/62);原发灶未能找到率1.61%(1/62).标准化摄取值(SUV)大于2.5占78.2%(111/142);SUV2.5~2.0占14.8%(21/142);SUV小于2.0占7%(10/142).结论PET-CT与单纯PET,CT比较具有明显的优势,可以精确定位、定性,但PET-CT也有一定的局限性. 相似文献
76.
《Journal of labelled compounds & radiopharmaceuticals》2003,46(8):699-713
The first application of a Sonogashira cross‐coupling reaction in 18F chemistry has been developed. The reaction was exemplified by the cross‐coupling of terminal alkynes (ethynylcyclopentyl carbinol 6 , 17α‐ethynyl‐3,17β‐estradiol 7 and 17α‐ethynyl‐3‐methoxy‐3,17β‐estradiol 8 ) with 4‐[18F]fluoroiodobenzene. 4,4′‐Diiododiaryliodonium salts were used as precursors for the synthesis of 4‐[18F]fluoroiodobenzene, enabling the convenient access to 4‐[18F]fluoroiodobenzene in 13–70% yield using conventional heating or microwave activation. The Sonogashira cross‐coupling of 4‐[18F]fluoroiodobenzene with terminal alkynes gave the corresponding 4‐[18F]fluorophenylethynyl‐substituted compounds [18F]‐9 , [18F]‐10 and [18F]‐13 in yields up to 88% within 20 min of starting from 4‐[18F]fluoroiodobenzene. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
77.
Abdominal Stab Wounds in Children: an 18-Year Experience 总被引:1,自引:0,他引:1
Hayrettin ?ztürk Abdurrahman Onen Selcuk Ot?u Ali hsan Dokucu Yusuf Yamur Senol Gedik 《European Journal of Trauma》2002,28(2):85-89
Objective: Evaluation of the diagnosis, management, and the role of selective treatment in children with abdominal stab wounds.
Patients and Methods: 59 children (56 male and three female) were included in the study. The patients' median age was 11.8 years (range, 5–14 years).
Time between injury and admission was about 3 h. Laparotomy was performed in 44 patients (74%). Solid organ injury was detected
in 32 of these patients (73%) and could not be observed in twelve (27%). 15 patients (26%) were treated conservatively, and
only one (6.6%) underwent laparotomy during the follow-up. The stomach was the most frequently injured organ (ten patients),
followed by the intestines (nine patients). Types of surgical treatment were as follows: primary suture in 28 patients, resection-anastomosis
in three, and osteotomy in two.
Results: Some prognostic factors such as presence of abdominal organ evisceration and pneumoperitoneum were not significantly correlated
with intraabdominal organ injury, whereas some other risk factors such as acute abdomen on admission (p < 0.002) or abdominal
clinical and hemodynamic findings (p < 0.001) showed significant correlation with intraabdominal organ injury. The relative
risk (odds ratio) of developing an intraabdominal organ injury was > 2 for patients with signs of an acute abdomen on admission.
Postoperative complications were observed in five patients with organ injuries. None of our patients died.
Conclusions: Conservative treatment can be safely performed in most children with abdominal stab injuries. Signs of major internal hemorrhage
or generalized peritonitis are an absolute indication for emergency operation for abdominal stab wounds. Peritoneal penetrations,
free air on the abdominal X-ray, and omental or intestinal evisceration are poor indicators of significant organ injuries,
and patients presenting these signs shold be closely followed up for developing acute abdominal symptoms.
Received: November 2, 2001; revision accepted: February 15, 2002 相似文献
78.
Mitsuhiko Yanagisawa M.D. 《Pediatrics international》1987,29(6):815-823
Using spontaneously established autologous lymphoblastoid B cell lines (LCL), killer cell activities were studied in children with severe infectious mononucleosis (IM), chronic IM, and acute IM, and compared with those in EBV-seropositive normal controls. Natural killer (NK) cell activity of fresh peripheral blood mononuclear cells (PBMC) was normal in acute IM patients, but it was low in four of six patients with severe or chronic IM. Recombinant inter-leukin 2 (rIL-2)-activated PBMC from normal controls showed lymphokine-activated killer (LAK) cell activity against the respective autologous LCL. The levels of LCL lysis by LAK cells were significantly higher in acute IM patients, lower in chronic IM patients, and much lower in severe IM patients. In contrast to the fact that PBMC stimulated in vitro with autologous LCL (IVS cells) from normal controls and acute IM patients showed potent killing of autologous LCL, IVS cells from severe or chronic IM patients showed lower levels of LCL lysis, which were markedly augmented in three patients by rIL-2 addition to the cultures. These killer cell dysfunctions appear to be responsible for the severe or chronic course of EBV infection. 相似文献
79.
D. G. Kim C.-Y. Kim S. H. Paek D. S. Lee J.-K. Chung H.-W. Jung B.-K. Cho 《Acta neurochirurgica》1998,140(7):665-674
Summary
Background To determine its roles in the diagnosis and the systemic evaluation of metastatic brain tumours, whole-body positron emission
tomography (PET) using [18F]FDG was performed in 20 consecutive patients.
Methods
All patients were thought to be suffering or needing to be differentiated from metastatic brain tumours. Nine patients had
multiple brain lesions; six were older and showed a rim-enhancing lesion with surrounding oedema; seven had homogeneously
enhancing periventricular lesion(s) on computed tomography (CT) and/or magnetic resonance (MR) imaging, thought to be central
nervous system lymphomas. Two patients had skull mass(es) and two patients had a solid mass suspected to be, respectively,
a haemorrhagic metastasis and a metastatic malignant melanoma. All of them received whole-body [18F]FDG PET and conventional systemic work-up for metastasis in order to compare the results of the two methods.
Results
Metastatic brain tumours were diagnosed on whole-body [18F]FDG PET in eleven patients who had extracranial and intracranial hypermetabolic lesions. In nine of these, a conventional
work-up also detected primary lesions which on whole-body [18F]FDG PET were seen to be hypermetabolic foci. Systemic lymph node metastases were detected by whole-body [18F]FDG PET only in two patients and histological diagnosis was possible by biopsy of lymph nodes rather than of brain lesions.
In the remaining nine patients who had only intracranial hypermetabolic foci, histological diagnosis was made by craniotomy
or stereotactic biopsy. It was confirmed that seven of nine patients were suffering from a primary brain tumour and two from
metastatic carcinoma. None of the nine showed evidence of systemic cancer on conventional work-up. Histological diagnoses
of the primary brain tumours were four cases of primary central nervous system lymphoma and one each of multifocal glioblastoma,
Ewing's sarcoma, and cavernous angioma.
Patients felt no discomfort during the whole-body [18F]FDG PET procedure and there were no complications. The false negative rate in [18F]FDG PET and in conventional work-up was 15.4% and 30.7% respectively. There were no false positives on either [18F]FDG PET or conventional work-up.
Conclusion
It is suggested that whole-body [18F]FDG PET is a safe, reliable, and convenient method for the diagnosis and systemic evaluation of patients thought to be suffering
or needing to be differentiated from a metastatic brain tumour. 相似文献
80.
Anthonie J. van Essen Coen J. F. Schoots Richard A. van Lingen Marian J. E. Mourits Joep H. A. M. Tuerlings Bieke Leegte 《American journal of medical genetics. Part A》1993,47(1):85-88
We report on the clinical and pathologic findings in a girl with isochromosome 18q (46, XX,i(18q)) who had combined manifestations of monosomy 18p and trisomy 18q. Major congenital anomalies included premaxillary agenesis, alobar holoprosenphaly, double Outlet right ventricle, DiGeorge anomaly and streak ovaries. The clinical spectrum in i(18q) is very broad. © 1993 Wiley-Liss, Inc. 相似文献