全文获取类型
收费全文 | 16140篇 |
免费 | 1119篇 |
国内免费 | 41篇 |
专业分类
耳鼻咽喉 | 256篇 |
儿科学 | 483篇 |
妇产科学 | 398篇 |
基础医学 | 1918篇 |
口腔科学 | 289篇 |
临床医学 | 1659篇 |
内科学 | 3165篇 |
皮肤病学 | 117篇 |
神经病学 | 1287篇 |
特种医学 | 650篇 |
外科学 | 2577篇 |
综合类 | 266篇 |
一般理论 | 13篇 |
预防医学 | 1332篇 |
眼科学 | 1074篇 |
药学 | 822篇 |
中国医学 | 20篇 |
肿瘤学 | 974篇 |
出版年
2023年 | 89篇 |
2022年 | 201篇 |
2021年 | 420篇 |
2020年 | 198篇 |
2019年 | 283篇 |
2018年 | 410篇 |
2017年 | 298篇 |
2016年 | 312篇 |
2015年 | 412篇 |
2014年 | 542篇 |
2013年 | 764篇 |
2012年 | 1153篇 |
2011年 | 1193篇 |
2010年 | 670篇 |
2009年 | 594篇 |
2008年 | 1036篇 |
2007年 | 1038篇 |
2006年 | 1025篇 |
2005年 | 1018篇 |
2004年 | 955篇 |
2003年 | 874篇 |
2002年 | 858篇 |
2001年 | 185篇 |
2000年 | 132篇 |
1999年 | 185篇 |
1998年 | 164篇 |
1997年 | 145篇 |
1996年 | 109篇 |
1995年 | 111篇 |
1994年 | 106篇 |
1993年 | 95篇 |
1992年 | 105篇 |
1991年 | 92篇 |
1990年 | 97篇 |
1989年 | 96篇 |
1988年 | 81篇 |
1987年 | 92篇 |
1986年 | 68篇 |
1985年 | 85篇 |
1984年 | 100篇 |
1983年 | 83篇 |
1982年 | 93篇 |
1981年 | 121篇 |
1980年 | 89篇 |
1979年 | 57篇 |
1978年 | 52篇 |
1977年 | 38篇 |
1976年 | 44篇 |
1975年 | 36篇 |
1974年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
21.
Jay Pratt 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1998,118(1):135-138
It is well known that the removal of a fixation point prior to the presentation of a peripheral target dramatically reduces
saccadic reaction time (SRT). This effect has become known as the “gap effect”. The present study examined several detailed
kinematic variables to determine whether the removal of the fixation point also affects the manner in which saccades are produced.
The findings indicate that saccades that were initiated after the removal of the fixation point had higher average velocities
and reached greater peak velocities, accelerations, and decelerations than did saccades produced in the presence of the fixation
point. The results suggest that the removal of the fixation point may affect the force-time curves of saccades in addition
to affecting the time needed to initiate the saccades.
Received: 21 February 1997 / Accepted: 24 July 1997 相似文献
22.
Harbhej Singh Jay Yang Katina Thornton Adolph H. Giesecke 《Journal canadien d'anesthésie》1995,42(11):987-991
The purpose of investigation was to study the effect of intrathecal fentanyl on the onset and duration of hyperbaric bupivacaine-induced spinal block in adult male patients. Fortythree patients undergoing lower extremity or genitourinary surgery were enrolled to receive either 13.5 mg hyperbaric bupivacaine 0.75% + 0.5 ml CSF it, (Group I) or 13.5 mg hyperbaric bupivacaine 0.75% + 25 μg fentanyl it, (Group II) according to a randomized assessor-blind protocol. The onset and duration of sensory block were assessed by pinching the skin with forceps in the midclavicular line bilaterally every two minutes for first twenty minutes and then every five to ten minutes. Similarly, the onset and duration of motor block were assessed and graded at the same time intervals using the criteria described by Bromage. The time required for two sensory segment regression and sensory regression to L1 dermatome was 74 ± 18 and 110 ± 33 min vs 93 ± 22 and 141 ± 37 min in Groups I and II, respectively (P < 0.05). Intrathecal fentanyl did not enhance the onset of sensory or motor block, or prolong the duration of bupivacaine-induced motor spinal block. Fewer patients demanded pain relief in the fentanyl-treated group than in the control group in the early postoperative period (19% vs 59%; P < 0.05). Episodes of hypotension were more frequent in the fentanyl-treated group than in the control group (43% vs 14%; P < 0.05). We conclude that fentanyl, 25 μg it, prolonged the duration of bupivacaine-induced sensory block (sensory regression to L1 dermatone) by 28% and reduced the analgesic requirement in the early postoperative period following bupivacaine spinal block. 相似文献
23.
24.
Periannan Kuppusamy Penghai Wang Michael Chzhan Jay L. Zweier 《Magnetic resonance in medicine》1997,37(4):479-483
The application of electron paramagnetic resonance imaging (EPRI) to obtain information from biological samples has been limited by the lack of ideal single line radical labels. The commonly used nitroxides exhibit multiple lines causing either hyperfine-based limitations in the maximum obtainable image resolution or hyperfine-based artifacts in the reconstructed image. The use of a novel single-line triarylmethyl paramagnetic label that enables marked enhancement in image quality and resolution is reported. This label exhibits a single line EPR spectrum that is sharp (linewidth ~60 mG in the absence of oxygen) and relatively stable in tissues. The potential of this label in enabling high resolution EPR imaging of biological samples was demonstrated in a series of phantoms and isolated biological organs such as the rat kidney. The images demonstrate that resolutions better than 100 μm could be obtained at L-band on samples of up to 20 mm in size. 相似文献
25.
Detection of the carrier state of X-linked retinoschisis 总被引:8,自引:0,他引:8
G B Arden M B Gorin P J Polkinghorne M Jay A C Bird 《American journal of ophthalmology》1988,105(6):590-595
We determined the extent of suppressive rod-cone interaction in 11 obligate carriers and eight potential carriers of X-linked retinoschisis from eight families. Despite otherwise normal ophthalmoscopic and functional testing, all of the obligate heterozygous carriers demonstrated a complete absence of normal rod-cone interaction. Of the potential heterozygous carriers, three had normal rod-cone interactions, two had no detectable interaction, and two yielded technically unsatisfactory results. This lack of rod-cone interactions allows heterozygous individuals to be identified clinically and has implications concerning the origin of this inherited disorder. 相似文献
26.
W M Jay R W Bradsher B LeMay N Snyderman E J Angtuaco 《American journal of ophthalmology》1988,105(4):366-370
We examined two patients with unilateral ophthalmologic findings secondary to pansinusitis caused by Bipolaris. Both patients were healthy young men. One patient had a gradual visual loss, whereas the other showed proptosis. Surgical debridement was the primary treatment in both patients. One patient received antifungal therapy, whereas the other was cured with surgery alone. 相似文献
27.
Hand-assisted laparoscopic nephroureterectomy for upper urinary tract transitional cell carcinoma. 总被引:1,自引:0,他引:1
Jay D Raman Michael A Palese Casey K Ng Stephen A Boorjian Douglas S Scherr Joseph J Del Pizzo R Ernest Sosa 《JSLS, Journal of the Society of Laparoendoscopic Surgeons》2006,10(4):432-438
OBJECTIVE: We report our experience with hand-assisted laparoscopic nephroureterectomy (HALN) for upper urinary tract transitional cell carcinoma and compare our results with a contemporary series of open nephroureterectomy (ON) performed at our institution. METHODS: Between August 1996 and May 2003, 90 patients underwent nephroureterectomy for upper-tract transitional cell carcinoma (TCC). Thirty-eight patients underwent HALN, while 52 had an ON. End-points of comparison included operative time, estimated blood loss (EBL), intraoperative and postoperative complications, length of hospital stay, pathologic grade and stage of tumor, and tumor recurrence. RESULTS: The mean patient age was 72.3 and 70.6 years in the ON and HALN groups, respectively. Mean operative duration was 243 minutes (ON) and 244 minutes (HALN), with an EBL of 478mL in the open group versus 191 mL in the hand-assisted group (P<0.001). No intraoperative complications occurred, but postoperative complications occurred in 4% and 11% of the ON and HALN groups, respectively (P=0.21). The mean hospital duration was 7.1 days (ON) versus 4.6 days (HALN) (P<0.01). No difference existed in the pathologic grade or stage distribution of urothelial tumors between the 2 groups. The mean follow-up was 51.0 months in the ON group and 31.7 months in the HALN group. Recurrence of urothelial carcinoma occurred in 50% of patients who underwent ON and 40% treated by HALN (P=0.38) at a median interval of 9.1 and 7.7 months, respectively, after surgery. CONCLUSION: Hand-assisted laparoscopic nephroureterectomy is an effective modality for the treatment of upper urinary tract urothelial carcinoma. Patients benefited from less intraoperative blood loss and a shorter hospitalization with an equivalent intermediate-term oncologic outcome compared with that of the open approach. 相似文献
28.
Kiran VEERAPEN Raman N. ASOKAN Vimalah RATHAKRISHNAN 《International journal of rheumatic diseases》2004,7(2):97-107
Aims: To create a clinical and radiological profile of patients with symptomatic osteoarthritis of the knee in Malaysia. Methods: One hundred consecutive patients presenting with symptomatic knee osteoarthritis at a private rheumatology clinic were profiled for demographic and clinical features. Anteroposterior weight‐bearing, skyline and lateral knee X‐rays were taken. Statistical Package for Social Sciences was used for data analysis. Results: Women predominated (93%). Fifty‐eight percent of the patients reported bilateral knee pain. Difficulty in walking, climbing and squatting was high (85%, 97% and 93% respectively). Patients with knee pain had a higher BMI than controls. Radiological abnormality, related to osteoarthritis was present in 97%. Osteophytes were generally tricompartmental while joint space narrowing was less evident in the lateral tibiofemoral joint than in the medial tibiofemoral joint and the patellofemoral joint. Almost half (49%) the patients manifested radiological varus deformity The severity of radiological abnormality increased with age. Although patients with unilateral pain had milder radiological abnormality, it tended to be bilateral. Clinically detectable hip abnormality and nodal osteoarthritis were uncommon, as was radiological chondrocalcinosis. Conclusions: Patients presenting with symptomatic knee osteoarthritis to a rheumatology service had a high degree of disability, radiological abnormality and varus deformity. Radiological abnormalities were essentially bilateral and tricompartmental. 相似文献
29.
Takeshi Sakata Yongmei Wang Bernard P Halloran Hashem Z Elalieh Jay Cao Daniel D Bikle 《Journal of bone and mineral research》2004,19(3):436-446
We showed that unloading markedly diminished the effects of IGF-I to activate its signaling pathways, and the disintegrin echistatin showed a similar block in osteoprogenitor cells. Furthermore, unloading decreased alphaVbeta3 integrin expression. These results show that skeletal unloading induces resistance to IGF-I by inhibiting activation of the IGF-I signaling pathways at least in part through downregulation of integrin signaling. INTRODUCTION: We have previously reported that skeletal unloading induces resistance to insulin-like growth factor-I (IGF-I) with respect to bone formation. However, the underlying mechanism remains unclear. The aim of this study was to clarify how skeletal unloading induces resistance to the effects of IGF-I administration in vivo and in vitro with respect to bone formation. MATERIALS AND METHODS: We first determined the response of bone to IGF-I administration in vivo during skeletal unloading. We then evaluated the response of osteoprogenitor cells isolated from unloaded bones to IGF-I treatment in vitro with respect to activation of the IGF-I signaling pathways. Finally we examined the potential role of integrins in mediating the responsiveness of osteoprogenitor cells to IGF-I. RESULTS: IGF-I administration in vivo significantly increased proliferation of osteoblasts. Unloading markedly decreased proliferation and blocked the ability of IGF-I to increase proliferation. On a cellular level, IGF-I treatment in vitro stimulated the activation of its receptor, Ras, ERK1/2 (p44/42 MAPK), and Akt in cultured osteoprogenitor cells from normally loaded bones, but these effects were markedly diminished in cells from unloaded bones. These results were not caused by altered phosphatase activity or changes in receptor binding to IGF-I. Inhibition of the Ras/MAPK pathway was more impacted by unloading than that of Akt. The disintegrin echistatin (an antagonist of the alphaVbeta3 integrin) blocked the ability of IGF-I to stimulate its receptor phosphorylation and osteoblast proliferation, similar to that seen in cells from unloaded bone. Furthermore, unloading significantly decreased the mRNA levels both of alphaV and beta3 integrin subunits in osteoprogenitor cells. CONCLUSION: These results indicate that skeletal unloading induces resistance to IGF-I by inhibiting the activation of IGF-I signaling pathways, at least in part, through downregulation of integrin signaling, resulting in decreased proliferation of osteoblasts and their precursors. 相似文献
30.