全文获取类型
收费全文 | 2691篇 |
免费 | 156篇 |
国内免费 | 153篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 91篇 |
妇产科学 | 38篇 |
基础医学 | 276篇 |
口腔科学 | 50篇 |
临床医学 | 418篇 |
内科学 | 496篇 |
皮肤病学 | 40篇 |
神经病学 | 205篇 |
特种医学 | 357篇 |
外科学 | 316篇 |
综合类 | 40篇 |
一般理论 | 5篇 |
预防医学 | 225篇 |
眼科学 | 52篇 |
药学 | 233篇 |
1篇 | |
肿瘤学 | 150篇 |
出版年
2021年 | 25篇 |
2020年 | 14篇 |
2019年 | 22篇 |
2018年 | 36篇 |
2017年 | 31篇 |
2016年 | 27篇 |
2015年 | 32篇 |
2014年 | 51篇 |
2013年 | 72篇 |
2012年 | 75篇 |
2011年 | 89篇 |
2010年 | 57篇 |
2009年 | 79篇 |
2008年 | 92篇 |
2007年 | 186篇 |
2006年 | 91篇 |
2005年 | 88篇 |
2004年 | 85篇 |
2003年 | 67篇 |
2002年 | 83篇 |
2001年 | 86篇 |
2000年 | 89篇 |
1999年 | 68篇 |
1998年 | 105篇 |
1997年 | 101篇 |
1996年 | 90篇 |
1995年 | 83篇 |
1994年 | 61篇 |
1993年 | 69篇 |
1992年 | 59篇 |
1991年 | 63篇 |
1990年 | 48篇 |
1989年 | 91篇 |
1988年 | 65篇 |
1987年 | 69篇 |
1986年 | 67篇 |
1985年 | 64篇 |
1984年 | 42篇 |
1983年 | 27篇 |
1982年 | 45篇 |
1981年 | 25篇 |
1980年 | 25篇 |
1979年 | 19篇 |
1978年 | 13篇 |
1977年 | 30篇 |
1976年 | 41篇 |
1975年 | 22篇 |
1972年 | 12篇 |
1971年 | 17篇 |
1970年 | 12篇 |
排序方式: 共有3000条查询结果,搜索用时 10 毫秒
1.
Further evidence of dopamine transporter dysregulation in ADHD: a controlled PET imaging study using altropane. 总被引:4,自引:0,他引:4
Thomas J Spencer Joseph Biederman Bertha K Madras Darin D Dougherty Ali A Bonab Elijahu Livni Peter C Meltzer Jessica Martin Scott Rauch Alan J Fischman 《Neuropsychopharmacology》2007,62(9):1059-1061
BACKGROUND: The dopamine transporter (DAT) is known to be a key regulator of dopamine, and recent studies of genetics, treatment, and imaging have highlighted the role of DAT in attention-deficit/hyperactivity disorder (ADHD). The findings of in vivo neuroimaging of DAT in ADHD have been somewhat discrepant, however. METHOD: Dopamine transporter binding was measured using a highly selective ligand (C-11 altropane) and positron emission tomography (PET). The sample consisted of 47 well-characterized, treatment-na?ve, nonsmoking, non-comorbid adults with and without ADHD. Additionally, control subjects had few symptoms of ADHD. RESULTS: Results showed significantly increased DAT binding in the right caudate in adults with ADHD compared with matched control subjects without this disorder. CONCLUSIONS: These results confirm abnormal DAT binding in the striatum of adults with ADHD and provide further support that dysregulation of DAT may be an important component of the pathophysiology of ADHD. 相似文献
2.
The effect of currently available contact lens disinfection systems on Acanthamoeba castellanii and Acanthamoeba polyphaga 总被引:6,自引:0,他引:6
R E Silvany J M Dougherty J P McCulley T S Wood R W Bowman M B Moore 《Ophthalmology》1990,97(3):286-290
Contact lens disinfection systems were evaluated for their effectiveness in killing Acanthamoeba castellanii and Acanthamoeba polyphaga trophozoites and cysts. Amoebae were inoculated into commercially available contact lens cleaning and soaking solutions. At intervals varying from 30 minutes to 24 hours, solutions were filtered. The filters were removed and cultured for Acanthamoeba organisms. Striking differences were observed in the abilities of the different disinfecting solutions to kill the organisms. Solutions containing chlorhexidine were effective at very short exposure times. Solutions containing benzalkonium chloride required slightly longer exposure times but were faster than solutions containing only thimerosal. Solutions containing sorbate, polyaminopropyl biguanide, or polyquaternium-1 were not effective at killing Acanthamoeba organisms in the time allotted for the experiment. Solutions containing hydrogen peroxide were quite effective if the agent was not prematurely catalyzed. A. polyphaga generally required longer exposure to disinfectants than did A. castellanii for complete inhibition to occur. 相似文献
3.
4.
P M Dougherty J Palecek V Paleckova L S Sorkin W D Willis 《The Journal of neuroscience》1992,12(8):3025-3041
The role of excitatory amino acids (EAAs) in the excitation of monkey spinothalamic tract (STT) neurons following activation of cutaneous primary afferent fibers by noxious and non-noxious stimuli was investigated. The responses of STT neurons to either NMDA or non-NMDA EAA ligands were blocked by infusion of specific antagonists through a microdialysis fiber into the region surrounding the cells. Our results show that blockade of non-NMDA receptors results in a nearly complete elimination of the responses of STT neurons to all stimuli. Blockade of NMDA receptors results in an attenuation of the responses to noxious stimuli but, in addition, prevents the development of the sensitization of STT neurons that is often observed after intradermal injection of capsaicin. These observations further support a role of EAAs in the transmission of sensory information from primary afferent fibers to dorsal horn neurons and a role for NMDA receptors in the generation of hyperalgesia. 相似文献
5.
Chris Chase Robert F Dougherty Nicola Ray Susan Fowler John Stein 《Optometry and vision science》2007,84(3):229-236
PURPOSE: Many behavioral studies have found impaired perception of dynamic visual stimuli in dyslexia and several neuroimaging studies have found reduced activation of the human motion area MT+ in dyslexia. These results are often interpreted as a magnocellular (MC) deficit in dyslexia. It has also been claimed that colored filters can help dyslexics to read. One defining feature of the MC-pathway is a greater weight for L-cone input than M-cone input, and at most very weak S-cone input. We measured the subjective speed matches between L-, M-, and S-cone isolating stimuli in good and poor readers. METHODS: Subjects performed a speed-matching task with drifting cone-isolating stimuli to find the point of subjective equality between two drifting patterns. Such a task is known to activate cortical area MT+, presumably via the MC-pathway. RESULTS: L- to M-cone speed-match ratios were negatively correlated with single-word (r=-0.46) and irregular-word reading (r=-0.56) but not with non-word reading. CONCLUSIONS: Results suggest that relative L-cone sensitivity within the MC-pathway may limit orthographic reading performance. 相似文献
6.
Dr. Steven A. Curley MD Robert A. Newman PhD Thomas B. Dougherty MD PhD George M. Fuhrman MD Diana L. Stone BS Jeffrey A. Mikolajek CRNA Sal Guercio CCP Ann Guercio CCP C. Humberto Carrasco MD M. Tien Kuo PhD David C. Hohn MD 《Annals of surgical oncology》1994,1(5):389-399
Background: We performed a phase I study of a novel system of complete hepatic venous isolation and extracorporeal chemofiltration in
patients with unresectable hepatocellular carcinoma (HCC) to determine (a) whether systemic exposure to doxorubicin could
be limited after high-dose hepatic arterial infusion (HAI), and (b) the hepatic maximum tolerated dose (MTD) of doxorubicin.
Methods: Ten patients with biopsy-proven HCC were treated with 20-min HAI of doxorubicin (17 total treatments). Two patients were
treated with doxorubicin 60 mg/m2, three patients were treated at 90 mg/m2, and five patients received 120 mg/m2. A newly developed dual-balloon vena cava catheter was advanced from the femoral vein, and the balloons were inflated to
isolate and capture total hepatic venous outflow. The hepatic venous blood was pumped through extracorporeal carbon chemofilters
before return of the blood to the systemic circulation.
Results: Peak systemic doxorubicin levels were an average 85.6% lower than were peak prefilter levels (p<0.01). Because all catheters
were placed percutaneously and because the chemofiltration markedly limited systemic chemotherapy exposure, patients were
discharged 1 day after 16 of the 17 treatments. The hepatic and systemic MTD of doxorubicin in this treatment protocol was
120 mg/m2.
Conclusions: This novel system of complete hepatic venous isolation and chemofiltration limits systemic chemotherapy toxicity and will
allow use of higher doses of chemotherapeutic agents to treat HCC.
The results of this study were presented at the 46th Annual Cancer Symposium of The Society of Surgical Oncology, Los Angeles,
California, March 18–21, 1993. 相似文献
7.
Dr. Joseph A. Kuhn MD Lawrence D. Wagman MD John A. Lorant MD Fredrick W. Grannis MD Mordecai Dunst MD William R. Dougherty MD Daniel I. Jacobs MD 《Annals of surgical oncology》1994,1(4):353-359
Background: A radical forequarter amputation with partial chest wall resection (one to four ribs) has been reported for benign and malignant
lesions involving the shoulder and chest wall region. Concerns about reconstruction and postoperative pulmonary function have
previously limited more extensive chest wall resections. The current report describes the first case in which a complete unilateral
anterior and posterior chest wall resection and pneumonectomy (hemithoracectomy) accompany a forequarter amputation. A novel
reconstructive technique used the full circumference of the forearm tissue with an intact ulna as a free osseomyocutaneous
flap.
Methods: In this case, a 21-year-old patient presented with an extensive recurrent desmoid tumor that involved the shoulder, brachial
plexus, subclavian vein, and chest wall from the lateral sternal border to the midportion of the scapula and down to the eighth
rib. The operative technique involved removal of the entire right hemithorax from the midline sternum to the transverse process
posteriorly, down to the ninth rib inferiorly. Due to the absence of a rigid hemithorax, the uninvolved ipsilateral lung was
also removed. The forearm flap was prepared before final separation of the specimen and division of the subclavian vessels.
Results: Postoperatively, the patient maintained excellent oxygenation without atelectasis or fever and was extubated on the 15th
postoperative day. As expected after pneumonectomy, significant decreases from preoperative to immediate postoperative values
were noted for the vital capacity (VC) (from 4.87 L to 1.29 L), forced 1-s expiratory volume (FEV1) (from 3.77 L to 1.02 L),
and inspiratory capacity (IC) (3.33 1 to 0.99 1). Rehabilitation included a specially designed external prosthesis to provide
cosmesis and prevent scoliosis. By the 15th postoperative week the patient had returned to normal social and physical activities,
with a gradual improvement in all respiratory parameters: VC 1.52 L, FEV1 1.29 L, IC 1.04 L. There has been no evidence of
tumor recurrence at 1 year.
Conclusions: This report provides evidence that a complete hemithoracectomy, pneumonectomy, and forequarter amputation can be safely performed
for selective tumors involving the shoulder region with extensive chest wall invasion. Reconstruction may be achieved with
an extended forearm osseomyocutaneous free flap with an excellent functional outcome.
Presented at the 46th Annual Cancer Symposium of The Society of Surgical Oncology, Los Angeles, California, March 18–21, 1993. 相似文献
8.
Intestinal schistosomiasis japonica: CT-pathologic correlation 总被引:1,自引:0,他引:1
Lee RC; Chiang JH; Chou YH; Rubesin SE; Wu HP; Jeng WC; Hsu CC; Tiu CM; Chang T 《Radiology》1994,193(2):539
9.
A method for dynamic imaging in MRI is presented that enables the acquisition of a series of images with both high temporal and high spatial resolution. The technique, which is based on the projection reconstruction (PR) imaging scheme, utilizes distinct data acquisition and reconstruction strategies to achieve this simultaneous capability. First, during acquisition, data are collected in multiple undersampled passes, with the view angles interleaved in such a way that those of subsequent passes bisect the views of earlier ones. During reconstruction, these views are weighted according to a previously described k-space weighted image contrast (KWIC) technique that enables the manipulation of image contrast by selective filtering. Unlike conventional undersampled PR methods, the proposed dynamic KWIC technique does not suffer from low image SNR or image degradation due to streaking artifacts. The effectiveness of dynamic KWIC is demonstrated in both simulations and in vivo, high-resolution, contrast-enhanced imaging of breast lesions. 相似文献
10.